CN220478148U - Comprehensive utilization system for hydrogen in cyclohexanone device by esterification method - Google Patents
Comprehensive utilization system for hydrogen in cyclohexanone device by esterification method Download PDFInfo
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- 239000001257 hydrogen Substances 0.000 title claims abstract description 413
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 413
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 358
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 title claims abstract description 139
- 238000000034 method Methods 0.000 title claims abstract description 113
- 238000005886 esterification reaction Methods 0.000 title claims abstract description 67
- 230000032050 esterification Effects 0.000 title claims abstract description 63
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims abstract description 184
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 159
- HGCIXCUEYOPUTN-UHFFFAOYSA-N cyclohexene Chemical compound C1CCC=CC1 HGCIXCUEYOPUTN-UHFFFAOYSA-N 0.000 claims abstract description 122
- HPXRVTGHNJAIIH-UHFFFAOYSA-N cyclohexanol Chemical compound OC1CCCCC1 HPXRVTGHNJAIIH-UHFFFAOYSA-N 0.000 claims abstract description 109
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims abstract description 80
- YYLLIJHXUHJATK-UHFFFAOYSA-N Cyclohexyl acetate Chemical compound CC(=O)OC1CCCCC1 YYLLIJHXUHJATK-UHFFFAOYSA-N 0.000 claims abstract description 72
- 150000002431 hydrogen Chemical class 0.000 claims abstract description 59
- 238000006356 dehydrogenation reaction Methods 0.000 claims abstract description 50
- 239000006227 byproduct Substances 0.000 claims abstract description 41
- 239000007789 gas Substances 0.000 claims description 266
- 238000010926 purge Methods 0.000 claims description 82
- 239000007788 liquid Substances 0.000 claims description 78
- 238000010521 absorption reaction Methods 0.000 claims description 55
- 238000000746 purification Methods 0.000 claims description 28
- 239000000446 fuel Substances 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 18
- 239000012071 phase Substances 0.000 claims description 10
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- 239000000463 material Substances 0.000 abstract description 4
- 230000001502 supplementing effect Effects 0.000 abstract description 2
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- 238000006243 chemical reaction Methods 0.000 description 69
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- 238000000926 separation method Methods 0.000 description 40
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- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 21
- 238000001816 cooling Methods 0.000 description 21
- 239000012535 impurity Substances 0.000 description 19
- 239000002994 raw material Substances 0.000 description 18
- 238000011084 recovery Methods 0.000 description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 15
- 239000003054 catalyst Substances 0.000 description 13
- 238000001704 evaporation Methods 0.000 description 12
- 230000008020 evaporation Effects 0.000 description 12
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 12
- 239000007795 chemical reaction product Substances 0.000 description 11
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 10
- 238000007670 refining Methods 0.000 description 10
- 229910052717 sulfur Inorganic materials 0.000 description 10
- 239000011593 sulfur Substances 0.000 description 10
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- 229910052757 nitrogen Inorganic materials 0.000 description 8
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- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 7
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- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Natural products CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 5
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- 239000000498 cooling water Substances 0.000 description 4
- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- ZSIAUFGUXNUGDI-UHFFFAOYSA-N hexan-1-ol Chemical compound CCCCCCO ZSIAUFGUXNUGDI-UHFFFAOYSA-N 0.000 description 4
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- 239000003507 refrigerant Substances 0.000 description 4
- 238000007086 side reaction Methods 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 3
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 150000001733 carboxylic acid esters Chemical class 0.000 description 3
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- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 3
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- CAKWRXVKWGUISE-UHFFFAOYSA-N 1-methylcyclopentan-1-ol Chemical compound CC1(O)CCCC1 CAKWRXVKWGUISE-UHFFFAOYSA-N 0.000 description 2
- ATQUFXWBVZUTKO-UHFFFAOYSA-N 1-methylcyclopentene Chemical compound CC1=CCCC1 ATQUFXWBVZUTKO-UHFFFAOYSA-N 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- YTPLMLYBLZKORZ-UHFFFAOYSA-N Thiophene Chemical compound C=1C=CSC=1 YTPLMLYBLZKORZ-UHFFFAOYSA-N 0.000 description 2
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 150000001335 aliphatic alkanes Chemical class 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 2
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- 239000012141 concentrate Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- NZNMSOFKMUBTKW-UHFFFAOYSA-N cyclohexanecarboxylic acid Chemical compound OC(=O)C1CCCCC1 NZNMSOFKMUBTKW-UHFFFAOYSA-N 0.000 description 2
- HPXRVTGHNJAIIH-PTQBSOBMSA-N cyclohexanol Chemical group O[13CH]1CCCCC1 HPXRVTGHNJAIIH-PTQBSOBMSA-N 0.000 description 2
- GJJASJCGLOUWAC-UHFFFAOYSA-N ethoxycyclohexane Chemical compound CCOC1CCCCC1 GJJASJCGLOUWAC-UHFFFAOYSA-N 0.000 description 2
- 235000019439 ethyl acetate Nutrition 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- GDOPTJXRTPNYNR-UHFFFAOYSA-N methylcyclopentane Chemical compound CC1CCCC1 GDOPTJXRTPNYNR-UHFFFAOYSA-N 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
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- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
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- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009903 catalytic hydrogenation reaction Methods 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
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- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- TVZPLCNGKSPOJA-UHFFFAOYSA-N copper zinc Chemical compound [Cu].[Zn] TVZPLCNGKSPOJA-UHFFFAOYSA-N 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- HFYLJNMQIGJQOQ-UHFFFAOYSA-N cyclohexanol;ethanol Chemical compound CCO.OC1CCCCC1 HFYLJNMQIGJQOQ-UHFFFAOYSA-N 0.000 description 1
- 125000002243 cyclohexanonyl group Chemical group *C1(*)C(=O)C(*)(*)C(*)(*)C(*)(*)C1(*)* 0.000 description 1
- 125000000113 cyclohexyl group Chemical group [H]C1([H])C([H])([H])C([H])([H])C([H])(*)C([H])([H])C1([H])[H] 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
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Abstract
The utility model discloses a comprehensive utilization system of hydrogen in a cyclohexanone device by an esterification method, which mainly comprises a benzene selective hydrogenation unit, a cyclohexene esterification addition unit, a cyclohexyl acetate hydrogenation unit, a cyclohexane hydrofining unit and a cyclohexanol dehydrogenation unit. The method comprises the comprehensive utilization of tail hydrogen emission of a benzene selective hydrogenation unit, hydrogen sources and hydrogen emission of a cyclohexyl acetate hydrogenation unit, hydrogen sources and tail hydrogen emission of a cyclohexane hydrofining unit and byproduct hydrogen of a cyclohexanol dehydrogenation reaction unit. The utility model discloses a treatment and utilization system of hydrogen in a device, combines the components of each discharged hydrogen or byproduct hydrogen, adopts mature and conventional technology to treat the discharged hydrogen or byproduct hydrogen at low cost without adopting a TSA (total hydrogen stream) or/and PSA (pressure swing adsorption) method, realizes the cascade utilization of the hydrogen in a cyclohexanone device, reduces the treatment capacity of the discharged hydrogen and the loss of valuable materials, reduces the new hydrogen supplementing amount of the device, reduces the production cost of the cyclohexanone by an esterification method, and has industrial application value.
Description
Technical Field
The utility model relates to the technical field of petrochemical industry, in particular to a comprehensive utilization system of hydrogen in an esterification cyclohexanone device, which comprehensively utilizes the hydrogen in the esterification cyclohexanone device.
Background
Cyclohexanone is an important chemical raw material, is an intermediate raw material for producing adipic acid, caprolactam, and important chemical products such as medicines, coatings, dyes and the like, and plays an important role in the coatings and textile industry. At present, the production methods of cyclohexanone mainly comprise a cyclohexane oxidation method, a phenol hydrogenation method, a cyclohexene hydration method and an industrialized cyclohexene esterification method; wherein, the oxidation conversion rate and selectivity of the cyclohexane oxidation method are low, the side reaction is more, and the safety is poor; the cost of phenol in the phenol hydrogenation method is high, and the economic competitiveness is not strong. Cyclohexene hydration is classified into direct hydration and indirect hydration; the direct hydration method is developed successfully by the Japan Xudio chemical industry company, in which benzene is firstly selectively hydrogenated to produce cyclohexene and a small amount of cyclohexane, the cyclohexene is directly hydrated to produce cyclohexanol by a molecular sieve catalyst, and the cyclohexanol is dehydrogenated to produce cyclohexanone. The product obtained by the method has good quality, high atom utilization rate and less three-waste emission; however, the once-through conversion rate of cyclohexene hydration reaction is about 10%, the water-to-olefin ratio is high, and a large amount of cyclohexene needs to be recycled, so that the investment and energy consumption are large. The indirect hydration method takes carboxylic acid as a medium to generate carboxylic acid ester, and then the carboxylic acid ester is hydrolyzed to obtain cyclohexanol, and the method has low conversion rate and selectivity and is not industrially applied.
In recent years, the domestic scientific research institute is greatly developing and perfecting a cyclohexene esterification method for producing cyclohexanol or/and cyclohexanone (called as ' esterification cyclohexanone ' for short), and the esterification method cyclohexanone is the latest process method for producing the cyclohexanol, and is a Green and low-cost cyclohexanol production method, which has good raw material adaptability, and is described in the literature ' Y.Zhu, L.Gao, L.Wen, et al, cyclohexene esterification-hydrogenation for efficient production of cyclohexanol [ J ]. Green chem.,2021,23,1185-1192 ]. Methods for the production of cyclohexanol and/or cyclohexanone by cyclohexene esterification are described, for example, in patent CN103657658A, CN103664528A, CN103664529A, CN103664531A, CN103664586A, CN106349011A, CN107434760A, CN107519881A, CN112892581A, CN113019391 a.
The cyclohexene esterification method for preparing cyclohexanol comprises three steps of benzene selective hydrogenation, cyclohexene esterification and cyclohexyl acetate hydrogenation; benzene selective hydrogenation was successfully developed by the japanese Asahi chemical industry and applied industrially for nearly 30 years; the cyclohexene and carboxylic acid are subjected to esterification reaction to generate ester, and then hydrogenation is carried out on the carboxylic acid ester to synthesize alcohol; both esterification and hydrogenation have high conversion and selectivity, with cyclohexyl conversion >99% and cyclohexanol selectivity >99% in CN104907071B, CN107434767 a; almost no three wastes are generated in the process, the method has higher atom economy, the reaction condition is relatively mild, the cheap acetic acid is generally adopted as the raw material, and the ethanol with higher added value is coproduced, so that the technical economy competitiveness can be obviously enhanced, and the method has better industrialized prospect. If the target product is cyclohexanone, adding a process step of preparing cyclohexanone by dehydrogenating cyclohexanol.
The cyclohexene esterification method has the defects of long process flow, corrosion occasions in production links, high operating pressure, high hydrogen consumption of unit product and the like, and the hydrogen consumption of each ton of cyclohexanone is 920-980 Nm 3 The method comprises the steps of carrying out a first treatment on the surface of the The hydrogen production system relates to a plurality of hydrogen units or systems, and the hydrogen quality and pressure requirements of each system are inconsistent; the main process steps and the hydrogen related characteristics are as follows:
1) Benzene selective hydrogenation cyclohexene production unit, and hydrogen consumption per ton product is about 660-690 Nm 3 The hydrogen quality requirements are very strict, especially harmful components such as sulfur, carbon monoxide, nitrogen organic compounds and the like, and a refining facility for hydrogen and raw material benzene is arranged in the unit, so that raw materials fed into the reactor are refined again, and the impurity content is reduced, such as: sulfur content less than 1ppb; the hydrogenation adopts a one-pass process, the hydrogenation temperature is moderate, but the operation pressure is high (the reaction temperature is 120-150 ℃, the reaction pressure is 4.5-5.5 MPa (G)), the benzene conversion rate is about 40-50%, the cyclohexene selectivity is about 75-80%, and the cyclohexane is a main byproduct; flash evaporation is carried out on the hydrogenation reaction product under the pressure of 0.4-0.5 MPa (G) to obtain gas-liquid two phases, the flash evaporation liquid is extracted and rectified to obtain recovered benzene, pure cyclohexene or/and a mixture of cyclohexene and cyclohexane, the flash evaporation gas is cooled to about 15 ℃ and is subjected to gas-liquid separation to obtain discharged tail hydrogen, and the discharge amount of the product per ton is about 10-20 Nm 3 Wherein the hydrogen content is about 95%, other components include water, methane, nitrogen, benzene, cyclohexene, cyclohexane and the like, and the content of harmful impurities is extremely low; for tail hydrogen discharge, some are sent to a factory fuel pipe network and some are sent to a hydrogen recovery device.
2) The cyclohexene addition esterification unit takes pure cyclohexene or cyclohexene mixture and acetic acid obtained by benzene selective hydrogenation as raw materials, the cyclohexene addition esterification reaction is cyclohexyl acetate, the reaction conditions are mild overall, and higher yield is obtained through a series of reactors; the reaction product is separated and refined in series, acetic acid and cyclohexene are recovered, and cyclohexane is separated out, so that the product cyclohexyl acetate is obtained; the unit is not involved in hydrogen utilization.
3) Cyclohexyl acetate hydrogenation unit, BThe cyclohexyl carboxylate and hydrogen are subjected to hydrogenation reaction in the presence of a copper catalyst to generate cyclohexanol and ethanol; the reaction temperature is high, the temperature is about 180-250 ℃, the reaction pressure is high, and the reaction pressure is about 4.5-6.0 MPa (G), which is a strong exothermic reaction, and a fixed bed reactor is adopted; the single pass conversion rate of the cyclohexyl acetate is about 99%, the cyclohexanol selectivity is above 98%, and a small amount of by-products of ethane, cyclohexane, methylcyclopentanol, ethylcyclohexyl ether, other ethyl esters and the like are produced; 2mol of hydrogen is theoretically consumed per 1mol of cyclohexyl acetate, and the hydrogen consumption per ton of product is about 460-500 Nm 3 The method comprises the steps of carrying out a first treatment on the surface of the In order to inhibit side reaction and improve reaction selectivity and hydrogen utilization rate, besides improving reaction pressure, hydrogen in reaction feed is greatly excessive, the mole ratio of hydrogen ester is high (10-50:1), hydrogenation adopts a circulating flow, and the hydrogen concentration of circulating hydrogen in a reaction system is lower than that of raw material new hydrogen; from the performance of the catalyst type, the quality requirement of the unit on raw material hydrogen is far lower than that of a benzene selective hydrogenation unit, and the conventional grade hydrogen of a factory can meet the requirement, so that the content of harmful components such as CO, sulfur and the like in the hydrogen can be mainly controlled.
4) The cyclohexanol dehydrogenation unit is used for carrying out dehydrogenation reaction on the refined cyclohexanol under the action of a catalyst to generate cyclohexanone and hydrogen, and the byproduct hydrogen of ton products is about 220-230 Nm 3 The method comprises the steps of carrying out a first treatment on the surface of the The reactor is a tube type fixed bed, copper series catalysts are usually used, the reaction temperature is 210-270 ℃, and the reaction pressure is micro-positive pressure. The effluent of the dehydrogenation reactor is subjected to heat exchange cooling and gas-liquid separation to obtain crude alcohol ketone liquid and gas mainly comprising byproduct hydrogen; the byproduct hydrogen contains a small amount of water, benzene, cyclohexene, cyclohexane, cyclohexanone, cyclohexanol and other impurities, and sometimes contains trace CO and methane, and does not contain harmful components such as sulfide, nitride and the like.
5) A cyclohexane hydrofining unit; hydrofining cyclohexane which is a byproduct of the reaction of the benzene selective hydrogenation unit, wherein the byproduct cyclohexane can be separated from a cyclohexene addition esterification unit; the nickel catalyst is usually adopted, and a small amount of benzene, cyclohexene and methylcyclopentene in cyclohexane are completely hydrogenated into corresponding saturated alkane in a trickle bed reactor; the hydrogenation condition is relatively mild (the reaction temperature is 110-160 ℃, the reaction pressure is 1.5-2.0 MPa (G)), and a one-pass hydrogenation process is generally adopted; relative to the two hydrogenation units The hydrogenation of the unit has the lowest requirement on the pressure and purity of hydrogen, but sulfides, water, high-boiling point organic matters and the like in the hydrogen cannot be excessively high; the hydrogen consumption in the hydrogenation process is small, and the hydrogen consumption is only about 9-12 Nm per ton of product 3 。
From the above, the esterification cyclohexanone production process, the hydrogen unit has inconsistent requirements on the quality of hydrogen, but in the conventional design process, the hydrogen sources of hydrogen points used by the benzene selective hydrogenation reaction unit, the esterification hydrogenation reaction unit and the cyclohexane hydrofining unit generally adopt pure new hydrogen (i.e. fresh hydrogen) from a boundary region; the method has the advantages of stable hydrogen quality, favorable production management, failure to utilize hydrogen with different qualities in a targeted way, excessive hydrogen quality with local gas points and overhigh pressure.
Due to the purity limitations of the reaction raw materials and hydrogen (usually containing a small amount of methane, nitrogen, etc.), and non-hydrogen components generated by side reactions, impurities accumulate in the reaction system or are concentrated in the reaction tail hydrogen, so that the concentration of hydrogen in the reaction tail hydrogen is reduced, and the impurity components are increased and the content is increased. For the cyclohexyl acetate hydrogenation unit in the circulation flow, in order to maintain the pressure and the reaction effect of the hydrogenation reaction system, the concentration of hydrogen in the circulating gas needs to be stabilized, and besides the new hydrogen is supplemented to the hydrogenation reaction system, a part of (usually 1-5% of the circulating hydrogen) circulating hydrogen (called as "purge gas") needs to be discharged from the reaction system, the main component of the purge gas is hydrogen, the inert gas component occupies a small part, and other components corresponding to the saturation pressure are also needed. For the hydrogenation unit of the one-pass flow, the reaction tail hydrogen component is related to the reaction characteristics, the raw material sources, the catalyst performance and the like, and the variation is large; in the production process of cyclohexanone by esterification, each hydrogenation unit discharges tail hydrogen, including purge gas, reaction tail hydrogen, dissolved gas and the like, and the discharged hydrogen has different hydrogen content and different impurity components.
Recovery (including purification) techniques for purge gas or tail hydrogen emissions have been quite mature. Such as: the hydrogen-containing tail gas of the Fischer-Tropsch synthesis of CN102703108A is purified by a Pressure Swing Adsorption (PSA) separation device to obtain hydrogen with the purity of 80-99 percent. CN104587797a adopts five-stage pressure swing adsorption to separate hydrogen production tail gas, and hydrogen with 99.95% molar purity can be obtained. CN111232924a first concentrates hydrogen to 90% by membrane separation and then concentrates hydrogen to greater than 99% by pressure swing adsorption. CN102718185 adopts the ionic liquid to support the device of liquid film purification hydrogen, the purity of hydrogen can reach 90%. The process devices similar to the device, such as: CN102942446A, CN105439816a is directed to an ethanol production device by acetate hydrogenation, and the PSA device is provided to recover hydrogen in purge gas and recycle the hydrogen, so as to reduce the loss of reactants, but the hydrogen recovery device is complex.
For the non-esterification cyclohexanone production method, mature hydrogen recycling and utilization technology exists. Such as:
the method is characterized in that the method adopts a technology of combining low-temperature separation and temperature swing adsorption to purify the waste gas. CN105688591a provides a process for recycling hydrogen-containing tail gas of a cyclohexanol production device, the hydrogen-containing tail gas produced by a benzene partial hydrogenation unit is compressed to 0.7-0.8 MPa (G) by a compressor, cooled to 8-12 ℃ and separated to obtain crude hydrogen, the crude hydrogen is adsorbed to obtain product hydrogen with water and impurities removed, hydrogen recycling is realized, and benzene, cyclohexene, cyclohexane and the like in the tail gas are recycled.
For byproduct hydrogen of cyclohexanol dehydrogenation units, most factories firstly cool and condense in a dehydrogenation device to remove most of organic matters, and then purify by adopting a PSA or Temperature Swing Adsorption (TSA) device after compression and pressure boosting. Such as: CN205495345U discloses a device for purifying hydrogen in caprolactam tail gas, and a method of combining TSA and PSA is used to separate cyclohexanone, cyclohexane, cyclohexanol, etc. in tail gas hydrogen to obtain high purity hydrogen. CN112023607a discloses a process for purifying hydrogen in tail gas, which comprises removing heavy aromatic hydrocarbon from tail gas by cooling with 2-10 ℃ chilled water, and sequentially carrying out TSA and PSA to obtain purified hydrogen, wherein the hydrogen yield is about 80%, and steam is required in the analysis process. The device comprises a plurality of temperature swing adsorption towers and a plurality of pressure swing adsorption towers, and has complex structure and complex purification process.
The existing factories are the same and similar devices, wherein tail hydrogen discharged from benzene selective hydrogenation reaction, tail hydrogen discharged from a cyclohexyl acetate hydrogenation unit (comprising purge gas, low-pressure gas and solution gas), tail hydrogen discharged from a cyclohexane hydrofining unit and byproduct hydrogen produced by a cyclohexanol dehydrogenation unit are usually discharged from a device, or sent to a hydrogen recovery device of the factory for concentrated purification, and the recovered hydrogen is integrated into a factory hydrogen pipe network or simply discharged to a fuel pipe network or a torch pipe network outside a boundary region; for concentrated purification of a hydrogen recovery device, because the hydrogen contains macromolecular organic matters, measures such as a TSA and PSA combined adsorption device or membrane separation are generally adopted; the hydrogen recovery device is used for concentrated purification, and usually, discharged hydrogen with different sources and different compositions is mixed and recovered together, so that the device has the characteristics of relatively convenient management and investment cost reduction, relatively more external exhaust gas during regeneration, and the hydrogen recovery rate is generally about 80%. The treatment mode of the discharged hydrogen to the fuel pipe network or the flare pipe network causes the waste of the hydrogen, and is generally used for treating the discharged hydrogen with small flow and low concentration, such as low-pressure gas, solution gas and the like.
Aiming at the cyclohexanone device by an esterification method, the research at home and abroad is mainly focused on the research of process conditions, catalyst preparation and main product separation schemes mainly based on tests. Such as patent CN103664530A, CN103664531A, CN103664587B, CN103880598A, CN107434760A, CN108003017A, CN109534954a. The research on the comprehensive application of the hydrogenation process flow and hydrogen in the device is less. CN114621051A, CN114621052a describes a process flow of cyclohexyl acetate hydrogenation, including a hydrogen circulation flow and a separation scheme of reaction products, but does not develop hydrogen optimization from the whole device level, and does not explicitly discharge a treatment mode of hydrogen.
As is known from the published literature, the hydrogen recovery, utilization and method of the cyclohexyl acetate hydrogenation unit which are completely the same as those of the utility model are not found, and the publication report of comprehensive and optimized hydrogen utilization from the device level of the cyclohexanone esterification method is not found, and the hydrogen cascade utilization in the device is not realized.
Disclosure of Invention
The esterification process cyclohexanone apparatus includes, but is not limited to, the following units or systems: a benzene selective hydrogenation unit (comprising raw material refining, hydrogenation reaction and reaction product separation system), a cyclohexene esterification unit (comprising esterification reaction and reaction product separation system) and a cyclohexyl acetate hydrogenation unit (comprising ester hydrogenation reaction and hydrogen circulation and reaction product separation system); cyclohexanol dehydrogenation unit (comprising cyclohexanol dehydrogenation, dehydrogenation product separation and hydrogen compression system). The utility model provides a process method for comprehensively utilizing hydrogen in an esterification cyclohexanone device, which optimizes the treatment and utilization of the hydrogen in the device and realizes the treatment and recycling of the hydrogen in the device with low cost; not only reduces the hydrogen consumption of the cyclohexanone device, but also reduces the recovery of the sent hydrogen, reduces the material loss, and realizes the improvement of the competitiveness of the cyclohexanone device by the esterification method.
A comprehensive utilization system and a process method of hydrogen in an esterification cyclohexanone device systematically optimize the treatment and application flow of the hydrogen in the device, and the method is realized by the following technical scheme:
the utility model provides a hydrogen comprehensive utilization system in esterification method cyclohexanone device, mainly comprises benzene selectivity hydrogenation unit, cyclohexene esterification addition unit, cyclohexane acetate hydrogenation unit, cyclohexane hydrofining unit, cyclohexanol dehydrogenation unit, its characterized in that: the new hydrogen feeding pipe is respectively connected with a benzene selective hydrogenation unit and a cyclohexyl acetate hydrogenation unit, and the benzene selective hydrogenation unit is connected with a cyclohexene esterification addition unit; the cyclohexane acetate pipeline of the cyclohexene esterification addition unit is connected with the cyclohexane acetate hydrogenation unit, and the crude cyclohexane pipeline is connected with the cyclohexane hydrofining unit; the cyclohexyl acetate hydrogenation unit is characterized in that a cyclohexanol pipeline is connected with a cyclohexanol dehydrogenation unit, a purge gas pipeline is connected with a cyclohexane hydrofining unit, and a desorption gas pipeline is connected with a factory fuel pipe network; the tail hydrogen discharge pipeline of the cyclohexane hydrofining unit is connected with a factory fuel pipeline network; the tail hydrogen discharge pipeline of the benzene selective hydrogenation unit, the byproduct hydrogen pipeline of the cyclohexanol dehydrogenation unit and the pure low-pressure gas distribution pipeline of the cyclohexyl acetate hydrogenation unit are mixed before the inlet of a hydrogen compressor, and the hydrogen outlet pipeline of the hydrogen compressor is connected with the cyclohexyl acetate hydrogenation unit.
The hydrogen compressor is arranged in the cyclohexanol dehydrogenation unit and can be a byproduct hydrogen compressor of the cyclohexanol dehydrogenation unit.
The cyclohexyl acetate hydrogenation unit consists of a hydrogenation reactor, a feeding heat exchanger, a feeding heater, a high-pressure gas separation cooler, a purge gas cooler, a low-pressure gas separation cooler, a high-pressure separator, a high-pressure condensate tank, a low-pressure separator, a circulating hydrogen press, a purge gas purifier and a low-pressure gas separation purifier.
The cyclohexyl acetate and the recycle hydrogen mixture feed pipe are connected with the hydrogenation reactor; the effluent pipeline of the hydrogenation reactor is connected with the hot side inlet of the feeding heat exchanger, the hot side inlet of the feeding heat exchanger is connected with the high-pressure separator, the high-pressure separator tank is provided with a high-pressure liquid outlet, and the top of the high-pressure separator tank is provided with a high-pressure gas outlet taking hydrogen as a main component; the high-pressure condensate tank is provided with a cold high-pressure gas outlet, and the cold high-pressure gas outlet is connected with a circulating hydrogen compressor; the new hydrogen and the recycled hydrogen pipeline are connected with the recycle hydrogen pipeline at the inlet of the recycle hydrogen compressor, then connected with the inlet of the recycle hydrogen compressor, the outlet of the recycle hydrogen compressor is connected with the cyclohexyl acetate feeding pipeline, then connected with the cold side inlet of the feeding heat exchanger, the cold side outlet of the feeding heat exchanger is connected with the feeding heater, and the outlet of the feeding heater is connected with the hydrogenation reactor.
The top of the high-pressure condensate tank is also provided with a purge gas outlet which is connected with a purge gas cooler, a gas phase outlet of the purge gas cooler is connected with a purge gas purification facility, and a liquid phase outlet of the purge gas cooler is connected with the high-pressure condensate tank. A small part of cold high-pressure gas is taken as purge gas to be discharged out of the hydrogen circulation system so as to control the hydrogen concentration in the circulating hydrogen at the inlet of the circulating hydrogen compressor to be more than 90 percent
The high-pressure separator tank bottom high-pressure liquid outlet is connected with the low-pressure separator, the top of the low-pressure separator is provided with a low-pressure gas outlet mainly comprising hydrogen, the low-pressure gas outlet is connected with a low-pressure gas cooler, the gas phase outlet of the low-pressure gas cooler is connected with a low-pressure gas purification facility, and the liquid phase outlet of the low-pressure gas cooler is connected with the low-pressure separator.
The purge gas purifier and the low-pressure gas purifier are both absorption towers.
The technological process of comprehensive utilization of hydrogen inside cyclohexanone apparatus with esterification includes the following steps:
a hydrogen source of the benzene selective hydrogenation unit adopts a hydrogen compression system for externally supplying new hydrogen and discharging tail hydrogen of hydrogenation reaction to a cyclohexanol dehydrogenation unit;
mixing tail hydrogen discharged from the benzene selective hydrogenation unit with byproduct hydrogen of the cyclohexanol dehydrogenation unit and pure low-pressure gas of the cyclohexyl acetate hydrogenation unit before an inlet of a hydrogen compressor of the cyclohexanol dehydrogenation unit, compressing the mixture by the hydrogen compressor, cooling and separating liquid to obtain recycled hydrogen, and sending the recycled hydrogen to the cyclohexyl acetate hydrogenation unit;
A hydrogen source of a cyclohexyl acetate hydrogenation unit, which adopts the recycled hydrogen from a cyclohexanol dehydrogenation unit, and the deficiency part is supplemented by new hydrogen supplied from the outside;
the discharged hydrogen of the cyclohexyl acetate hydrogenation unit comprises purge gas, low-pressure gas and dissolved gas, the purge gas and the low-pressure gas are treated by an added separation process, and then the purge gas and the low-pressure gas are respectively sent to a cyclohexane hydrofining unit and a cyclohexanol dehydrogenation unit;
a hydrogen source of the cyclohexane hydrofining unit adopts pure purge gas of the cyclohexane acetate hydrofining unit;
the tail hydrogen discharged from the cyclohexane hydrofining unit is sent out to a factory fuel pipe network or a hydrogen recovery device.
The fresh hydrogen, supplied from the outside of the apparatus, has a hydrogen volume fraction greater than 95%, preferably greater than 99%, more preferably greater than 99.9%;
further, the new hydrogen, wherein the mass fraction of sulfur is not more than 0.1ppm, CO 2 And the volume fraction of (C) is not more than 10ppm.
The benzene selective hydrogenation unit comprises a raw material refining system, a hydrogenation reaction system, a reaction product separation system and the like;
further, the new hydrogen is refined in the unit, and then enters the hydrogenation reactor, wherein the sulfur mass fraction of the new hydrogen is not more than 0.3 ppb.
Further, the raw material benzene is refined in the unit, and then enters the hydrogenation reactor, wherein the sulfur mass fraction of the raw material benzene is not more than 1.0 ppb.
Further, the operating pressure of the benzene selective hydrogenation reaction is 4.0 to 6.0MPa (G), preferably 4.5 to 5.5MPa (G);
further, the benzene selective hydrogenation reaction is operated at a temperature of 100 to 180 ℃, preferably 125 to 150 ℃.
The tail hydrogen discharged by the benzene selective hydrogenation unit is the gas obtained by flash evaporation of reaction effluent of a hydrogenation reactor to obtain flash gas, cooling and liquid separation of the flash gas, and sending the flash gas to a cyclohexanol dehydrogenation unit.
Flash evaporation and flash evaporation liquid are obtained from the reaction effluent of the hydrogenation reactor through flash evaporation separation, and most of water, cyclohexene, benzene and cyclohexane in the flash evaporation gas are removed through cooling and gas-liquid separation to obtain discharged tail hydrogen; the volume fraction of hydrogen in the discharged tail hydrogen is high (about 95%), other components include water, nitrogen, cyclohexane, cyclohexene, benzene and the like, the content of harmful impurities is extremely low, and the tail hydrogen can be reused in the device without special treatment; but the flow is not large, the pressure is low, and the discharge amount of ton products is about 10-20 Nm 3 The method comprises the steps of carrying out a first treatment on the surface of the Such as discharging it into a fuel network, valuable hydrogen, benzene and cyclohexene will be lost.
Further, the pressure of the discharged tail hydrogen is 0.3 to 0.8MPa (G), preferably 0.4 to 0.6MPa (G); the pressure is determined by the flash pressure, and the flash pressure is low, so that more dissolved gas is released, but the content of organic matters and water in flash steam is increased, and the cold energy consumption in cooling the flash steam is increased.
Further, the temperature of the discharged tail hydrogen is 10 to 30 ℃, preferably 12 to 20 ℃. The temperature of the flash steam after being cooled is low, which is favorable for better recycling organic matters in the flash steam.
The byproduct hydrogen of the cyclohexanol dehydrogenation unit, which is generated when cyclohexanol is dehydrogenated to generate cyclohexanone, is the reaction effluent of a cyclohexanol dehydrogenation reactor, and is obtained through repeated heat exchange cooling and gas-liquid separation, so that the content of most organic matters (such as cyclohexanone and cyclohexanol) is removed; the byproduct hydrogen contains a small amount of impurities such as water, cyclohexene, cyclohexane, cyclohexanone, cyclohexanol and the like, and does not contain other impurities except trace COHarmful impurities, which have the possibility of being reused in the device; 220-235 Nm of ton product byproduct 3 。
Further, the temperature of the byproduct hydrogen is 10 to 60 ℃, preferably 15 to 45 ℃. The temperature of byproduct hydrogen is obtained after cooling and liquid separation of reaction products, and the low temperature is favorable for recovering and removing more organic matters, and is determined by integrating pressure drop of a reaction system, power consumption of a compressor and consumption of a public refrigerant.
Further, the pressure of the byproduct hydrogen is 0.00 to 0.50MPa (G), preferably 0.001 to 0.20MPa (G). This pressure is limited by the cyclohexanol dehydrogenation reaction pressure, typically a micro positive pressure.
And mixing the byproduct hydrogen with the discharged tail hydrogen from the benzene selective hydrogenation unit and the pure low-pressure gas of the cyclohexyl acetate hydrogenation unit before the inlet of a hydrogen compressor of the cyclohexanol dehydrogenation unit, and then compressing the mixture by the hydrogen compressor to obtain compressed hydrogen.
And the compressed hydrogen is cooled and separated from gas and liquid, so that the contents of water, cyclohexanol, cyclohexanone, cyclohexane, cyclohexene and the like in the gas are further reduced, and the recycled hydrogen is obtained.
The byproduct hydrogen of cyclohexanol dehydrogenation or purge gas discharged from a hydrogenation unit is usually recycled by adopting a TSA and PSA combined device to remove water, organic matters and other gases in the purge gas to obtain high-purity hydrogen, but the process consumes energy, and about 20% of the gas is discharged in the regeneration process to be lost. The inventor researches that the conventional processes of pressure boosting, cooling and gas-liquid separation can effectively reduce the content of organic matters and water in the water, especially the content of cyclohexanol and cyclohexanone; the device mainly uses hydrogen to realize high pressure of hydrogen needed by hydrogen points, and the high pressure is more beneficial to reducing the organic matter content in the compressed hydrogen; the inventor also discovers that the recycled hydrogen obtained by the technical measures has better compatibility with the hydrogenation reaction environment of the cyclohexyl acetate hydrogenation unit, has low harmful impurities, does not form obvious adverse effects on the reaction processes of esterification hydrogenation and cyclohexane hydrofining, does not influence the quality of related products, and can meet the requirement of the cyclohexyl acetate hydrogenation unit on the quality of hydrogen. And recycling cyclohexane, cyclohexene, cyclohexanone and cyclohexanol in the hydrogen to finally become a part of target products.
Further, the temperature of the recycled hydrogen is 10 to 45 ℃, preferably 12 to 20 ℃. The method is that the lower the temperature of the recycled hydrogen obtained by cooling the compressed hydrogen is, the content of components such as cyclohexane, cyclohexanol, cyclohexanone and the like in the recycled hydrogen is reduced, and the circulation of the components in the system is reduced; but too low a cooling temperature will consume more energy.
Furthermore, the recycled hydrogen is connected to the part of the circulating hydrogen system in the cyclohexyl acetate hydrogenation unit, which can be before the hydrogen inlet of a circulating hydrogen compressor (for short, "circulating hydrogen compressor") or after the hydrogen outlet of the circulating hydrogen compressor, and is preferably connected to the circulating hydrogen system before the hydrogen inlet of the circulating hydrogen compressor. The specific accessible location may be a recycle hydrogen press inlet buffer tank.
Still further, the pressure of the recycled hydrogen is 1.0MPa, preferably 0.5MPa, more preferably 0.1MPa, higher than the pressure at the addition site. The position of the recycled hydrogen connected to the circulating hydrogen system influences the determination of the hydrogen outlet pressure of the hydrogen compressor in the cyclohexanol dehydrogenation unit; the pressure of the compressed hydrogen and the recycled hydrogen is determined, the invention has no special requirement, and a professional engineer in the field can determine the pressure according to conventional engineering design or engineering knowledge calculation so that the recycled hydrogen can smoothly enter a circulating hydrogen system.
The process method for comprehensively utilizing the hydrogen in the cyclohexanone device by the esterification method further comprises a treatment process for discharging hydrogen by a cyclohexyl acetate hydrogenation unit.
The reaction effluent of the hydrogenation reactor in the cyclohexyl acetate hydrogenation unit exchanges heat with reaction feed, is cooled to 100-180 ℃, enters a high-pressure separator for gas-liquid separation to obtain high-pressure hydrogen-containing gas (high-pressure gas for short) and high-pressure separation liquid (high-pressure liquid for short), the high-pressure gas is cooled and enters a high-pressure condensate tank for gas-liquid separation again to obtain cold high-pressure gas and high-pressure condensate, and the cold high-pressure gas is divided into two paths: one path enters a circulating hydrogen compressor to be boosted and circulated back to the hydrogenation reactor, and the other path is purge gas.
In order to maintain the concentration of the recycle hydrogen in the hydrogenation reaction system and balance the concentration of impurities, a part of the recycle hydrogen is discharged from the recycle hydrogen system, and the main component of the purge gas is usually hydrogen. For a cyclohexyl acetate hydrogenation unit, the purge gas volume per ton of product is about 15-30 Nm 3 Related to purity of new hydrogen, reaction by-products, reaction conditions, etc.; the purge gas contains, in addition to hydrogen, a small amount of ethanol, water, ethane, cyclohexane, cyclohexanol, and inert and harmful components derived from new hydrogen.
And (3) further cooling the purge gas, and separating gas from liquid to obtain 'dry purge gas', wherein the 'dry purge gas' is treated by the purification process A to obtain pure purge gas, and the pure purge gas is directly sent to a cyclohexane refining unit without pressurization. The measures are to control the contents of components such as water, ethanol, cyclohexane and the like in the purge gas.
And the high-pressure liquid enters a low-pressure separator for flash evaporation, so that the obtained gas is low-pressure gas and the liquid is low-pressure liquid.
And distilling the high-concentration liquid and the low-concentration liquid in the unit to separate out a target product. In the subsequent separation process, light components such as hydrogen and the like dissolved in the high-fraction condensate and the low-fraction condensate are separated out when distilled or evaporated to form solution gas; the dissolved gas is sent to a factory fuel pipe network because of containing relatively more light hydrocarbon, ethanol and other impurities and having small flow.
And (3) further cooling the low-pressure gas, separating gas from liquid to obtain dry low-pressure gas, treating the dry low-pressure gas by a purification process B to obtain pure low-pressure gas, and sending the pure low-pressure gas to a cyclohexanol dehydrogenation unit.
Further, the gas-liquid separation of the high pressure separator is operated at a pressure lower than the hydrogenation reactor operating pressure by 1.0MPa, preferably 0.5MPa, more preferably 0.1MPa. The specific operating pressure is determined comprehensively by technical and economic factors such as the operating pressure of an upstream hydrogenation reactor, the flow of circulating hydrogen, the arrangement of equipment pipelines and the like.
Further, the pressure difference between the high-pressure separator and the high-pressure condensate tank is not more than 0.5MPa, preferably 0.1MPa, more preferably 0.05MPa. The pressure difference is mainly determined by the pressure drop of the high-pressure gas in the conveying process from the high-pressure separator to the high-pressure condensate tank through the cooler, and the smaller the pressure difference is, the higher the pressure of the high-pressure gas is, which is more beneficial to reducing the content of components such as water, light hydrocarbon, ethanol and the like in the gas; the higher the pressure of the high-pressure condensate tank is, the more energy-saving of the circulating hydrogen compressor is facilitated.
Further, the flash pressure of the low pressure separator is 0.4 to 1.2MPa (G), preferably 0.8 to 1.0MPa (G). The flash pressure of the low-pressure separator is high, and the obtained flash gas is less, but the concentration of hydrogen is higher; the flash pressure is low, the obtained flash gas is more, but the concentration of hydrogen is lower, the concentration of organic matters is increased, and the ethanol content is particularly increased; the pressure is determined comprehensively according to the low-split gas composition and the subsequent treatment of the low-split liquid.
Further, the high-pressure gas before entering the high-pressure condensate tank is cooled to 30 to 60 ℃, preferably 40 to 50 ℃. The lower the cooling temperature of the high-pressure gas is, the more favorable the removal of water and organic matters in the gas, so as to obtain cold high-pressure gas, but the lower-temperature refrigerant with higher cost is needed; and the obtained high-segregation condensate is still required to be heated when being separated at the downstream; usually, circulating cooling water is used as a refrigerant to cool the high-pressure gas to 40-50 ℃.
Further, the purge gas is cooled to 10 to 40 ℃, preferably 12 to 20 ℃. The purge gas is further cooled, and part of water and organic matters in the gas are condensed into liquid, and the liquid is removed through gas-liquid separation.
Further, the purification process comprises one or a combination of a purification process A and a purification process B, optionally an adsorption process or/and a gas absorption process, preferably a gas absorption process.
Optionally, an adsorption process is adopted, components such as ethanol, water and cyclohexanol in the purge gas are adsorbed by the adsorbent, and when adsorption is saturated, the adsorbent is regenerated and resolved by adopting circulating hydrogen with the temperature of not lower than 150 ℃ in the unit, and resolved gas is discharged to a fuel pipe network.
Still further, in the gas absorption process, one or a mixture of cyclohexanone, cyclohexanol and cyclohexyl acetate is used as absorption liquid, and the absorption liquid is contacted with purge gas (or low-pressure gas) in an absorption tower to absorb most of organic matters in the gas, so that the absorption rich liquid is obtained.
Further, the purge gas has a hydrogen purity of 90 mol% or more.
Still further, the purification process a and the purification process B may be the same principle process or different principle process, and preferably the same principle process is adopted. The same principle process means that the adsorption process principle is adopted, or the gas absorption process principle is adopted, and preferably, the gas absorption process is adopted, so that the management and the operation are convenient.
Specifically, the gas absorption process takes one or a mixture of cyclohexanone, cyclohexanol and cyclohexyl acetate as an absorption liquid, preferably cyclohexanol containing 1-5% of cyclohexanone by mass percent or cyclohexanol containing 1-50% of cyclohexyl acetate by mass percent, and specifically can be one or a combination of cyclohexanol light ends removal tower liquid, cyclohexanone tower liquid, cyclohexanol tower overhead and cyclohexyl acetate recovery tower overhead in patent CN 114763318A; the absorption liquid is sent to the top of the absorption tower and is in countercurrent contact with purge gas (aiming at the purification technology B, low-pressure gas), water and partial organic matters in the gas are absorbed and purified, the content of components such as water, ethanol and the like in the purge gas (or low-pressure gas) is further reduced, and the purified purge gas (or low-pressure gas) contains a small amount of cyclohexanol except inert gas (such as nitrogen, methane and ethane); and the absorption liquid absorbing the organic matters and water in the gas becomes the absorption rich liquid.
Still further, for purification process A, the absorber operating pressure is not lower than 0.5MPa, preferably 0.1MPa, more preferably 0.05MPa, of the high pressure condensate tank operating pressure. The gas absorption process should be performed at as high an operating pressure as possible to improve the absorption effect and reduce the organic content of the absorbed hydrogen.
The inventor carries out fine calculation and experiments, the purge gas is treated according to the method provided by the invention, and the organic matters (such as cyclohexanol, ethanol, cyclohexanone content is not more than 50ppm (Vol)) in the treated hydrogen, free water is not present in the hydrogen, other harmful components are low in content, adverse effects on the nickel catalytic hydrogenation process in a cyclohexane refining unit are not formed, the cyclohexanol and cyclohexanone content in the hydrogen is low, the hydrogen flow is small, the amount of the hydrogen finally dissolved in cyclohexane is extremely low, the effect on cyclohexane quality is hardly caused, a small amount of light components such as ethanol, ethane and the like in the hydrogen are distilled out from the top of a cyclohexane rectifying tower and enter light oil. In particular, the byproduct hydrogen of the cyclohexanol dehydrogenation unit is used as part of hydrogen source of the cyclohexyl acetate unit, which is favorable for reducing the contents of harmful components (such as sulfur, nitrogen and the like) in the circulating hydrogen and purge gas, and is more favorable for implementing the method of the invention. When the technical method of the invention is implemented, the concentration of the hydrogen in the purge gas is lower than that of the hydrogen in the new hydrogen, and the same hydrofining effect can be obtained by properly increasing the hydrogenation pressure and/or slightly increasing the reaction temperature and increasing the flow of the discharged tail hydrogen.
Specifically, under normal working conditions, the hydrogen amount in the purge gas of the esterification hydrogenation system (15-30 Nm per ton of product) 3 ) More hydrogen than is required for the refined hydrogenation of cyclohexane (9 to 12Nm per ton of product 3 ) The method comprises the steps of carrying out a first treatment on the surface of the The esterification hydrogenation reaction pressure is far higher than the operation pressure (1.2-1.8 MPa under normal conditions) of the cyclohexane refining hydrogenation process, and the purge gas is directly used for the cyclohexane refining hydrogenation process without compression.
Further, the low-pressure gas is cooled to 10 to 50 ℃, preferably 12 to 20 ℃. The low-pressure gas is cooled further, part of water and organic matters in the low-pressure gas are condensed into liquid, and the liquid is removed through gas-liquid separation; and the temperature is low, and the next purification process is facilitated.
The purification process A and the purification process B are the same, so that organic matters and other components in the gas are further removed, the gas and the cyclohexanol absorption liquid are contacted in an absorption tower, and ethanol and other components in the gas enter a cyclohexanol solution. The adsorption process and the gas absorption process are all conventional chemical operation units in the chemical industry, the principles and the process flows of the adsorption process and the gas absorption process are described in Yuan Weikang, wang Jingkang and the like, the volume 2 of the chemical engineering manual, the gas absorption [ M ] of 12, the adsorption and ion exchange [ M ] of 18, and the chemical industry press, 2019. "for gas absorption processes, it is well known to those skilled in the art that the absorption effect can be improved by either reducing the temperature of the absorption liquid and the circulating absorption liquid, or increasing the flow rate of the absorption liquid, by operating at as high an operating pressure as possible. The professional engineer can reasonably determine the operating pressure of the absorption process according to the upstream pressure of the gas, the actual needs of the process and the equipment, and determine the detailed flow of the absorption process, the flow rate, the temperature and other operating conditions of the absorption liquid of each section according to the absorption requirement and the physical property.
Specifically, the purge gas after being treated by the purification process A controls the ethanol and cyclohexanol content in the purge gas after being treated (pure purge gas) to be not more than 25ppm (Vol) and 50ppm (Vol), respectively; the excessive cyclohexanol and ethanol content in the purge gas has a certain influence on the performance of the catalyst, and high-value ethanol and cyclohexanol products are lost; after the reaction of the hydrofining unit, the ethanol and the cyclohexanol are mainly enriched in cyclohexane, and the ethanol and the cyclohexanol respectively enter light oil and cyclohexane in a separation tower.
Specifically, the content of ethanol and cyclohexanol in the low-pressure gas (pure low-pressure gas) after the treatment of the low-pressure gas treated by the purification technology B is controlled to be respectively not more than 150ppm (Vol) and 300ppm (Vol); after the pure low-pressure gas is compressed, cooled and separated from gas and liquid in a cyclohexanol dehydrogenation unit, most of cyclohexanol and part of ethanol in the low-pressure gas enter a crude alcohol ketone solution as condensate, wherein the ethanol finally enters a light component, and the cyclohexanol is recovered; the cyclohexanol and ethanol remained in the low-pressure gas are returned to the ester hydrogenation unit together.
And the pure low-pressure gas is sent to a cyclohexanol dehydrogenation unit, is mixed with other hydrogen before the inlet of a hydrogen compressor, and is compressed and separated for recycling.
Still further, the temperature of the absorption liquid is not more than 45 ℃, preferably not more than 35 ℃, more preferably not more than 30 ℃; the low temperature is beneficial to absorption, and the determination of the temperature is carried out by considering absorption requirements and energy consumption and combining the comprehensive determination of the fluidity of the absorption liquid.
Further, the rich absorption liquid is sent to corresponding refining facilities of the unit for treatment. Such as the ethanol-cyclohexanol separation column of the return patent CN 114763318A.
The discharged tail hydrogen of the cyclohexane hydrofining unit is sent out to a fuel pipe network or a hydrogen recovery device; said discharged tail hydrogen of the cyclohexane hydrofinishing unit,is the inert gas and other impurities brought by the concentration of new hydrogen in the device, the noncondensable gas dissolved in the materials in the process, and the byproduct low boiling point components in the reaction process, including nitrogen, methane, ethane, CO and CO 2 The method also comprises other organic gases in the production process, the hydrogen concentration is low, and the hydrogen is difficult to treat by the conventional process and is recycled in the device.
Compared with the conventional technology, the invention has the following beneficial effects:
aiming at the characteristics and quality requirements of each hydrogen point of the cyclohexanone device by an esterification method, the technology combines the composition of each discharged hydrogen or byproduct hydrogen, adopts no TSA or/and PSA method, adopts mature and conventional technology to treat the discharged hydrogen or byproduct hydrogen at low cost, realizes the cascade utilization of hydrogen in the cyclohexanone device, reduces the treatment capacity of the discharged hydrogen and the loss of valuable materials, reduces the new hydrogen supplementing amount of the device, reduces the production cost of the cyclohexanone by the esterification method, and has industrial application value.
In the present specification, MPa (G) means gauge pressure, nm 3 Refers to the volume of gas at 0 degrees celsius at 1 standard atmospheric pressure; ppm is typically expressed as a percentage of the total solution mass, ppb is typically expressed as a percentage of the total solution mass, ppm (Vol), ppm (mol) are expressed as volume, mol% concentration, respectively,% (wt) is expressed as a percentage of the mass, and% (Vol) is expressed as a percentage of the volume; these are well known techniques, units or symbols.
In the description of the present utility model, it is to be understood that the term "ton product" refers in particular to cyclohexanone product per ton; the terms "dry purge gas", "pure purge gas", "dry low-split gas", "pure low-split gas", and the like merely denote the relative degree of water and organic matter in the gas, and are not to be construed as the concept of "no" or "pure".
Drawings
FIG. 1 is a schematic diagram of a system for comprehensive utilization of hydrogen in an esterification cyclohexanone device of the present utility model.
FIG. 2 is a schematic flow diagram of the hydrogen process of comparative example 1.
FIG. 3 is a schematic diagram of the hydrogen treatment of the cyclohexyl acetate hydrogenation system in the cyclohexanone device by esterification according to the utility model.
R01-hydrogenation reactor, E01-feeding heat exchanger, E02-feeding heater, E03-high-pressure gas separator, E04-purge gas cooler, E05-low-pressure gas separator, V01-high-pressure separator, V02-high-pressure condensate tank, V03-low-pressure separator, K01-circulating hydrogen press, X01-purge gas purifier and X02-low-pressure gas purifier.
S01-cyclohexyl acetate, S02-reaction feed after heat exchange, S03-new hydrogen, S04-recycle hydrogen after compression, S05-reactor feed, S06-reactor effluent, S07-reaction effluent after heat exchange, S08-high-pressure gas, S09-cold high-pressure gas, S10-recycle hydrogen, S11-purge gas, S12-purge gas condensate, S13-dry purge gas, S14-pure purge gas, S15-high-pressure condensate, S20-high-pressure gas, S21-low-pressure gas, S22-low-pressure gas condensate, S23-dry low-pressure gas, S24-pure low-pressure gas, S25-low-pressure gas, S31-recycle hydrogen.
CM: represents coolant feed, including but not limited to circulating cooling feed water or low-temperature cooling feed water; CMR: represents refrigerant outflow, including but not limited to circulating cooling backwater or low-temperature cooling backwater; HM: represents a heating medium including, but not limited to, steam; HMR: representing a heating medium including, but not limited to, steam condensate.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention.
Detailed Description
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed for the description of the embodiments will be briefly introduced below, it being obvious that the drawings in the following description are only schematic of the embodiments of the present invention; the number of devices or lines in the drawing, or the number of devices, is not representative of the plant configuration of only those devices or devices in the drawing.
The following technical scheme is a preferred technical scheme of the invention, but is not a limitation of the technical scheme provided by the invention, and the technical purpose and beneficial effects of the invention can be better achieved and realized through the following technical scheme.
The comprehensive utilization system of hydrogen in the cyclohexanone device by an esterification method mainly comprises a benzene selective hydrogenation unit, a cyclohexene esterification addition unit, a cyclohexyl acetate hydrogenation unit, a cyclohexane hydrofining unit and a cyclohexanol dehydrogenation unit, wherein a new hydrogen feeding pipe is respectively connected with the benzene selective hydrogenation unit and the cyclohexyl acetate hydrogenation unit, and the benzene selective hydrogenation unit is connected with the cyclohexene esterification addition unit; the cyclohexane acetate pipeline of the cyclohexene esterification addition unit is connected with the cyclohexane acetate hydrogenation unit, and the crude cyclohexane pipeline is connected with the cyclohexane hydrofining unit; the cyclohexyl acetate hydrogenation unit is characterized in that a cyclohexanol pipeline is connected with a cyclohexanol dehydrogenation unit, a purge gas pipeline is connected with a cyclohexane hydrofining unit, and a desorption gas pipeline is connected with a factory fuel pipe network; the tail hydrogen discharge pipeline of the cyclohexane hydrofining unit is connected with a factory fuel pipeline network; the tail hydrogen discharge pipeline of the benzene selective hydrogenation unit, the byproduct hydrogen pipeline of the cyclohexanol dehydrogenation unit and the pure low-pressure gas distribution pipeline of the cyclohexyl acetate hydrogenation unit are mixed before the inlet of a hydrogen compressor, and the hydrogen outlet pipeline of the hydrogen compressor is connected with the cyclohexyl acetate hydrogenation unit.
Example 1
The following describes the embodiments of the present invention in detail with reference to the technical scheme and the accompanying drawings. The technology of the invention is further described by taking a 10 ten thousand ton/year esterification cyclohexanone device as an example.
Raw material benzene: the benzene content is more than or equal to 99.95 percent (wt), the sulfur content is less than or equal to 1.0ppm, and the thiophene content is less than or equal to 0.1ppm;
new hydrogen: the hydrogen content is more than or equal to 99.9 percent (Vol), CO 2 < 10ppm (Vol), CO < 10ppm (Vol), sulfur < 0.1ppm, CH 4 ＜50ppm(Vol)，H 2 O＜10mg/m 3 。
1) Benzene selective hydrogenation unit
Refining new hydrogen to obtain reaction hydrogen with total sulfur content not higher than 0.1ppb and CO+CO2 content not higher than 20ppm, compressing and then carrying out selective hydrogenation reaction with refined benzene in a serial hydrogenation reactor with catalyst function to generate cyclohexene, wherein the reaction is carried out at the pressure of 4.5-5.0 MPaG and the temperature of 125-145 ℃, the benzene conversion rate is about 42%, the cyclohexene selectivity is about 80%, and the main byproduct cyclohexane is obtained; the hydrogenation adopts a one-pass process. Introducing the hydrogenation reaction effluent into a flash tank, and performing gas-liquid separation at 0.4MPa (G) to obtain an oil phase containing benzene, cyclohexene and cyclohexane and a gas phase containing hydrogen; cooling the gas phase to about 15 ℃ and then carrying out gas-liquid separation, recovering organic matters in a liquid form, and obtaining discharged tail hydrogen; the content of hydrogen in the discharged tail hydrogen is about 95%, other components comprise water, methane, nitrogen, benzene, cyclohexene, cyclohexane and the like, and harmful impurities such as sulfide and nitrogen oxide are less than 1ppm, and the harmful impurities are sent to a hydrogen compression system of a cyclohexanol dehydrogenation unit for compression and treatment for recycling. The oil phase containing benzene, cyclohexene and cyclohexane is subjected to extraction rectification in the next working procedure, the benzene is recovered and recycled, and the obtained mixture of cyclohexene and cyclohexane is sent to a cyclohexene esterification unit.
The flow rate of the new hydrogen from outside the boundary region is 8350Nm 3 /h (100% hydrogen, the same applies below);
the unit discharges tail hydrogen with a hydrogen content of 95% (Vol) and a hydrogen flow of 182.5Nm 3 /h。
2) Cyclohexene esterification unit
Pure cyclohexene or cyclohexene mixture from benzene selective hydrogenation unit and externally supplied raw material acetic acid are subjected to addition esterification reaction of cyclohexene and acetic acid in a series of esterification reactors under the action of a catalyst at high pressure and medium temperature to generate cyclohexyl acetate, the reaction product is refined through a complex separation process to obtain cyclohexyl acetate product, and acetic acid is recovered and recycled to obtain cyclohexane with acetic acid and ester components removed; the unit is not involved in hydrogen utilization.
3) Cyclohexyl acetate hydrogenation unit
A mixture of cyclohexyl acetate and circulating hydrogen (S05) which is subjected to heat exchange and heating to 190 ℃ is fed into a fixed bed reactor (R01) which is provided with a copper-based catalyst in parallel connection; in the reactor (R01), the cyclohexyl acetate is subjected to selective hydrogenation reaction under the action of a catalyst and hydrogen, and a reaction effluent (S06) contains cyclohexanol, ethanol, byproduct ethane and the like generated by the reaction, and unreacted hydrogen and unreacted ester; the reaction temperature is 180-210 ℃, the reaction pressure is 5.1-5.2 MPaG, the reaction is a strong exothermic reaction, and the heat released by the reaction is removed through a Cooling Medium (CM) of a shell side; the single pass conversion rate of the cyclohexyl acetate is about 99%, the cyclohexanol selectivity is more than 99%, by-products such as a small amount of ethane, cyclohexane, methylcyclopentanol, ethyl acetate, ethyl cyclohexyl ether and the like are produced, and a certain amount of unreacted cyclohexyl carboxylate and a small amount of high-boiling substances are contained in the reaction effluent; the molar ratio of the hydrogen to the ester is high (20:1), and the hydrogenation adopts a circulating flow.
The effluent (S06) of the hydrogenation reactor passes through a reaction effluent/raw material heat exchanger (E01) and is cooled to about 130 ℃, the cooled reaction effluent (S07) enters a high-pressure separator (V01), gas-liquid separation is carried out at the pressure of 4.8-5.0 MPaG, high-fraction liquid (S20) mainly comprising ethanol and cyclohexanol is separated from the bottom of a high-pressure separator tank (V01), and high-fraction gas (S08) mainly comprising hydrogen is separated from the top of the high-pressure separator tank; cooling the high-pressure gas to 45 ℃ cold high-pressure gas (S09) through circulating cooling water, entering a high-pressure condensate tank (V02), and then carrying out gas-liquid separation under the pressure of 4.8-5.0 MPaG, wherein high-pressure condensate (S15) mainly comprising ethanol is separated from the bottom of the high-pressure condensate tank (V02); the top of the high-pressure condensate tank (V02) is separated into cold high-pressure gas, most of the cold high-pressure gas is taken as circulating hydrogen (S10) to a circulating compressor (K01), and the small part of the cold high-pressure gas is taken as purge gas (S11) to be discharged out of a hydrogen circulating system so as to control the concentration of hydrogen in the circulating hydrogen at an inlet of the circulating hydrogen compressor to be more than 90%; the new hydrogen (S03) and the recycled hydrogen (S31) are mixed with the recycled hydrogen (S10) at the inlet of a recycle hydrogen press, and compressed to 5.5MPaG through the recycle hydrogen press (K01) to obtain compressed recycle hydrogen (S04); then mixing with cyclohexyl acetate (S01), exchanging heat in E01, heating to 190 ℃ which is close to the hydrogenation reaction temperature in a feed heater (E02), and then entering a hydrogenation reactor (R01). The recycled hydrogen (S31) comes from the compression of the cyclohexanol dehydrogenation unit and is treated to obtain hydrogen.
The purge gas (S11) is cooled to 12 ℃ by low-temperature cooling water in a purge gas cooler (E04), and is subjected to gas-liquid separation under the pressure of 4.8-5.0 MPaG to obtain high-fraction condensate (S) taking ethanol as a main purge gas condensate (S12) and hydrogen as a main 'dry purge gas' (S13); the dry purge gas (S13) is sent to purification process a (X01).
The high-pressure liquid separated from the tank bottom of the high-pressure separator (S20) enters the low-pressure separator (V03), is subjected to adiabatic flash evaporation under the pressure of 0.8-1.0 MPaG (the temperature is about 75 ℃), low-pressure liquid mainly comprising cyclohexanol and ethanol is obtained from the tank bottom (S25), and low-pressure gas mainly comprising hydrogen is separated from the top (S21). The low-pressure gas (S21) is cooled to 12 ℃ in a low-pressure gas cooler (E05) by low-temperature cooling water, and the dry low-pressure gas (S23) is obtained by gas-liquid separation, the obtained liquid is low-pressure gas condensate (S22) automatically flows to a low-pressure separator (V03), and is mixed with flash evaporation liquid in a tank to form low-pressure liquid (S25), and the dry low-pressure gas (S23) is subjected to a purification process B (X02).
The hydrogenation reaction liquid product formed by the high-fraction condensate and the low-fraction condensate is continuously rectified, and the ester hydrogenation product is separated into various components or target products including ethanol, cyclohexanol, light and heavy impurities generated by side reaction and unreacted completely cyclohexyl acetate through a series of rectifying towers.
For the purification process A (X01) of the dry purge gas, the hydrogen volume concentration of the dry purge gas (S13) is more than 90%, the volume flow is 268.8Nm3/h, the operating pressure of an absorption tower is 4.7-4.9 MPaG, the absorption liquid is an alcohol tower top distillate product, the component is cyclohexanol containing cyclohexanone (3% by mass fraction), the flow is 100kg/h, the absorption liquid is cooled to 25 ℃ and added from the top of the absorption tower, the absorption rich liquid is contacted with the dry purge gas entering from the bottom of the absorption tower and subjected to mass transfer and heat transfer, the absorption rich liquid absorbing ethanol and the like is obtained at the tower bottom, the pure purge gas (S14) with the ethanol and the cyclohexanol content not higher than 25ppm (Vol) and 50ppm (Vol) is obtained at the top of the tower, and the pure purge gas (S14) is fed to a cyclohexane hydrofining unit.
For the purification process B (X02) of the dry low-pressure gas, the hydrogen volume concentration of the dry low-pressure gas (S23) is about 80 percent, the volume flow is 100Nm3/h, the operating pressure of an absorption tower is 0.7-0.8 MPaG, the absorption liquid is an alcohol tower top product, the component is cyclohexanol containing cyclohexanone (3 percent by mass fraction), the flow is 300kg/h, the absorption liquid is cooled to 25 ℃ and added from the absorption tower top, the absorption rich liquid is contacted with the dry low-pressure gas entering from the bottom of the absorption tower in the tower, mass transfer and heat transfer occur, the absorption rich liquid absorbing organic matters such as ethanol is obtained at the tower bottom, the pure low-pressure gas (S24) with the ethanol and the cyclohexanol content not higher than 150ppm (Vol) and 300ppm (Vol) is obtained at the tower top, and the pure low-pressure gas (S24) is fed to a cyclohexanol dehydrogenation unit.
The hydrogen consumption of the unit in hydrogenation reaction hour is 6300Nm 3 /h, wherein the amount of new hydrogen from outside the boundary region is 3142.5Nm 3 And/h, the amount of recycle hydrogen from the cyclohexanol dehydrogenation unit was 3157.5Nm 3 /h。
The unit discharges tail hydrogen:
the flow rate of the discharged purge gas was 268.8Nm 3 And/h, ethanol content of 0.01kg/h and cyclohexanol of 0.06kg/h.
Pure low-pressure gas is discharged with the flow rate of 100.0Nm 3 And/h, ethanol content of 0.03kg/h and cyclohexanol of 0.13kg/h.
The amount of dissolved air discharged was 50Nm 3 And/h, ethanol content is 2.5kg/h.
4) Cyclohexanol dehydrogenation unit
Cyclohexanol obtained from the top of the alcohol tower and/or refined cyclohexanol from a cyclohexanol storage tank is subjected to heat exchange through a series of heat exchangers, vapor phase alcohol is obtained through evaporation through an evaporator, the vapor phase alcohol is subjected to heat exchange to 220-240 ℃ and then enters a tube array type fixed bed dehydrogenation reactor, cyclohexanone and hydrogen are generated through alcohol dehydrogenation under the catalysis of a zinc-copper catalyst, the reaction temperature is 220-240 ℃, the reaction pressure is micro-positive pressure, the once-through conversion rate of the cyclohexanol is 50%, and the selectivity of the cyclohexanone is 99%; the reaction absorbs heat to react, and heat is provided to the reactor by the heat conducting oil to maintain the temperature required by the reaction. Cooling and condensing the effluent of the dehydrogenation reactor through multiple heat exchange to obtain crude alcohol ketone liquid of liquid-phase crude cyclohexanone and cyclohexanol and gas mainly containing byproduct hydrogen; the unit produces hydrogen as byproduct, the benzene selective hydrogenation unit discharges tail hydrogen and pure low-pressure gas of the cyclohexyl acetate hydrogenation unit, the tail hydrogen and the pure low-pressure gas are mixed in a buffer tank at an inlet of a hydrogen compressor, then the mixture enters the hydrogen compressor, the outlet pressure of the compressor is 5.5MPaG, compressed hydrogen is cooled to 12 ℃ by a hydrogen cooler, the recycled hydrogen is obtained after liquid separation, the recycled hydrogen contains a small amount of water, and impurities such as benzene, cyclohexene, cyclohexane, cyclohexanone, cyclohexanol and the like, does not contain harmful components such as sulfide, nitride and the like, and is sent to the cyclohexyl acetate hydrogenation unit.
The hydrogen amount of the byproduct of the dehydrogenation reaction of the unit is as follows: 2875Nm 3 /h；
The amount of tail hydrogen discharged from the benzene selective hydrogenation unit: 187.5Nm 3 /h；
Pure low gas split from cyclohexyl acetate hydrogenation unit: 100Nm 3 /h；
The amount of recycle hydrogen sent to the cyclohexyl acetate hydrogenation unit by the unit: 3157.5Nm 3 /h。
5) Cyclohexane hydrofining unit
Cyclohexane is a benzene selective hydrogenation byproduct of a benzene selective hydrogenation unit and is separated from a cyclohexene addition esterification unit; and (3) preheating the cyclohexane subjected to deacidification and dehydration to 100 ℃ by a feed heater, and then feeding the cyclohexane into the top of a cyclohexane hydrogenation reactor. Completely hydrogenating a small amount of benzene, cyclohexene and methylcyclopentene in cyclohexane into corresponding saturated alkane in a trickle bed reactor; a nickel catalyst is adopted, the reaction temperature is 100-120 ℃, the reaction pressure is 1.5-2.0 MPaG, and a one-pass hydrogenation process is adopted; hydrogen and oil-phase cyclohexane are added from the top of the reactor, and hydrogenation tail gas is continuously discharged from the bottom of the reactor, so that inert gas accumulation is prevented. And discharging the hydrogenation reaction product from the bottom of the reactor, then feeding the reaction product into a cyclohexane refining tower for rectification, and distilling light oil comprising methyl cyclopentane and the like from the tower top, thereby obtaining the target product cyclohexane from the tower bottom. The purity of the obtained refined cyclohexane is not lower than 99.9% (wt), wherein the content of benzene and cyclohexene is less than 100ppm. Discharging hydrogen-containing tail gas and dissolved hydrogen and light components from the bottom of the reactor, and discharging the hydrogen-containing tail gas and the light components to a fuel pipe network.
The reaction hydrogen of the unit is from purge gas treated by a cyclohexyl acetate hydrogenation unit in the device, and the flow is 268.8Nm 3 /h。
The unit discharges tail hydrogen: 193.8Nm 3 And/h, wherein cyclohexane content is 5.30kg/h, and discharging the mixture to a fuel pipe network.
Comparative example 1
The production scale, unit composition, unit main body process flow, raw materials and specifications of comparative example 1 were the same as those of example 1. The following description will be made mainly with respect to differences.
1) Benzene selective hydrogenation unit
The process and process conditions were the same as in example 1; the new hydrogen was also from outside the boundary zone at the same flow rate as in example 1; the unit discharges tail hydrogen with a hydrogen content of 95% (Vol) and a flow of 187.5Nm 3 And/h, also as in example 1.
Unlike example 1:
the unit discharges tail hydrogen and the hydrogen recovery device is used for centralized treatment.
2) Cyclohexene esterification unit
Identical; the unit is not involved in hydrogen utilization.
3) Cyclohexyl acetate hydrogenation unit
The overall process and operating conditions were the same, except for example 1:
the hydrogen consumption of the unit in hydrogenation reaction hour is 6300Nm 3 /h, all from fresh hydrogen outside the boundary region (6300 Nm 3 /h)。
The dry purge gas obtained by the same process and operation conditions is discharged to a hydrogen recovery device without being treated by a gas absorption process.
The dry low-pressure gas obtained by the same process and operation condition is discharged to a fuel pipe network without being treated by a gas absorption process.
The unit discharges tail hydrogen:
the flow rate of the discharged purge gas was 268.8Nm 3 And/h, ethanol content of 0.27kg/h and cyclohexanol of 0.03kg/h.
Pure low-pressure gas is discharged with the flow rate of 100.0Nm 3 And/h, ethanol content of 0.63kg/h and cyclohexanol of 0.07kg/h.
The amount of dissolved air discharged was 50Nm 3 And/h, ethanol content is 2.5kg/h.
4) A cyclohexanol dehydrogenation unit,
the process and the operation conditions of the unit are completely the same as those of the unit corresponding to the embodiment 1, and the difference device does not compress and cool hydrogen of other units. The hydrogen byproduct of the unit is sent to a hydrogen recovery device after being treated by the flow and the conditions described in the embodiment 1.
The hydrogen amount of the byproduct of the unit is as follows: 2825Nm 3 /h；
The unit is used for delivering hydrogenHydrogen amount of the gas recovery device: 2825Nm 3 And/h, wherein cyclohexanol + cyclohexanone is about 2.2kg/h.
5) Cyclohexane hydrofining unit
The unit process and operating conditions were identical to those of the corresponding unit of example 1, except that the hydrogen source for the hydrogenation reaction was the same.
The hydrogen consumption of the hydrogenation reaction of the unit: 150Nm 3 And/h, all from the new hydrogen amount outside the boundary region (150 Nm 3 /h)；
The unit discharges tail hydrogen: 75Nm 3 And/h, wherein the cyclohexane content is 2.15kg/h, and discharging the mixture to a fuel pipe network.
Example 1 and comparative example 1 main parameters are shown in Table 1, and it can be seen from Table 1 that after adopting the technology of the invention, the device for discharging tail hydrogen or byproduct hydrogen of 10 ten thousand tons of cyclohexanone per year is subjected to low-cost treatment, so that the hydrogen can be recycled or utilized in steps in the device without 3326Nm 3 And/h, delivering the hydrogen to a factory hydrogen recovery device for treatment. The hydrogen recovery device regenerates and analyzes the exhausted hydrogen gas by about 3326×20+=665 Nm 3 Per hour, gas is in 1 yuan/Nm 3 Only this year is the cost saved by about 532 ten thousand yuan.
Table 1 comparison of the main parameters of example 1 and comparative example 1
The foregoing is merely an embodiment of the present application, and is not intended to limit the present application, but the present application is disclosed in the preferred embodiment, however, it is not intended to limit the present application, and any person skilled in the art may make some changes or modifications using the disclosed technical content and equivalents to the equivalent embodiments without departing from the scope of the technical solution of the present application.
Claims (8)
1. The utility model provides a hydrogen comprehensive utilization system in esterification method cyclohexanone device, mainly comprises benzene selectivity hydrogenation unit, cyclohexene esterification addition unit, cyclohexane acetate hydrogenation unit, cyclohexane hydrofining unit, cyclohexanol dehydrogenation unit, its characterized in that: the new hydrogen feeding pipe is respectively connected with a benzene selective hydrogenation unit and a cyclohexyl acetate hydrogenation unit, and the benzene selective hydrogenation unit is connected with a cyclohexene esterification addition unit; the cyclohexane acetate pipeline of the cyclohexene esterification addition unit is connected with the cyclohexane acetate hydrogenation unit, and the crude cyclohexane pipeline is connected with the cyclohexane hydrofining unit; the cyclohexyl acetate hydrogenation unit is characterized in that a cyclohexanol pipeline is connected with a cyclohexanol dehydrogenation unit, a purge gas pipeline is connected with a cyclohexane hydrofining unit, and a desorption gas pipeline is connected with a factory fuel pipe network; the tail hydrogen discharge pipeline of the cyclohexane hydrofining unit is connected with a factory fuel pipeline network; the tail hydrogen discharge pipeline of the benzene selective hydrogenation unit, the byproduct hydrogen pipeline of the cyclohexanol dehydrogenation unit and the pure low-pressure gas distribution pipeline of the cyclohexyl acetate hydrogenation unit are mixed before the inlet of a hydrogen compressor, and the hydrogen outlet pipeline of the hydrogen compressor is connected with the cyclohexyl acetate hydrogenation unit.
2. The comprehensive utilization system of hydrogen in an esterification cyclohexanone device according to claim 1, wherein the hydrogen compressor is arranged in a cyclohexanol dehydrogenation unit and is a byproduct hydrogen compressor of the cyclohexanol dehydrogenation unit.
3. The comprehensive utilization system of hydrogen in an esterification cyclohexanone device according to claim 1, wherein the cyclohexyl acetate hydrogenation unit consists of a hydrogenation reactor, a feed heat exchanger, a feed heater, a high-pressure gas separator, a purge gas cooler, a low-pressure gas separator, a high-pressure condensate tank, a low-pressure separator, a recycle hydrogen press, a purge gas purifier and a low-pressure gas purifier.
4. The comprehensive utilization system of hydrogen in an esterification cyclohexanone device according to claim 3, wherein the feeding pipeline of the mixture of cyclohexyl acetate and circulating hydrogen is connected with a hydrogenation reactor; the effluent pipeline of the hydrogenation reactor is connected with the hot side inlet of the feeding heat exchanger, the hot side inlet of the feeding heat exchanger is connected with the high-pressure separator, the high-pressure separator tank is provided with a high-pressure liquid outlet, and the top of the high-pressure separator tank is provided with a high-pressure gas outlet taking hydrogen as a main component; the high-pressure condensate tank is provided with a cold high-pressure gas outlet, and the cold high-pressure gas outlet is connected with a circulating hydrogen compressor; the new hydrogen and the recycled hydrogen pipeline are connected with the recycle hydrogen pipeline at the inlet of the recycle hydrogen compressor, then connected with the inlet of the recycle hydrogen compressor, the outlet of the recycle hydrogen compressor is connected with the cyclohexyl acetate feeding pipeline, then connected with the cold side inlet of the feeding heat exchanger, the cold side outlet of the feeding heat exchanger is connected with the feeding heater, and the outlet of the feeding heater is connected with the hydrogenation reactor.
5. The comprehensive utilization system of hydrogen in an esterification cyclohexanone device according to claim 3, wherein the top of the high-pressure condensate tank is also provided with a purge gas outlet connected with a purge gas cooler, a gas phase outlet of the purge gas cooler is connected with a purge gas purification facility, and a liquid phase outlet of the purge gas cooler is connected with the high-pressure condensate tank.
6. The comprehensive utilization system of hydrogen in the esterification cyclohexanone device according to claim 3, wherein the high-pressure separator tank bottom high-pressure liquid outlet is connected with a low-pressure separator, the top of the low-pressure separator is provided with a low-pressure gas outlet mainly containing hydrogen, the low-pressure gas outlet is connected with a low-pressure gas cooler, the gas phase outlet of the low-pressure gas cooler is connected with a low-pressure gas purification facility, and the liquid phase outlet of the low-pressure gas cooler is connected with the low-pressure separator.
7. The system for comprehensive utilization of hydrogen in an esterification cyclohexanone device according to claim 3, wherein the purge gas purifier is an absorption tower.
8. The system for comprehensive utilization of hydrogen in a cyclohexanone device by esterification according to claim 3, wherein the low-pressure gas purifier is an absorption tower.
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