CN101445419A - Method for separating lower hydrocarbon containing light gas by combining distillation and solvent absorption - Google Patents
Method for separating lower hydrocarbon containing light gas by combining distillation and solvent absorption Download PDFInfo
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Abstract
The invention relates to a method for separating lower hydrocarbon containing light gas by combining distillation and solvent absorption, comprising the steps as follows: (1) pre-disposed gas at the outlet of a reactor is cooled to the temperature ranging from 10 DEG C to -37 DEG C and sent to a pre-cutting tower; (2) the gas at the outlet of the pre-cutting tower is sent to an absorption tower and C1 and C2 in the gas are separated by taking C3 or C4 or C5 or C6 or hydrocarbon mixtures as absorbent; (3) outcomes generated at the bottom of the absorption tower are sent to the pre-cutting tower; with C2 distillate further absorbed and methane and lighter components removed in the pre-cutting tower, the outcome is sent to a deethanizer so that the C2 and C3 are clearly cut. Compared with the prior art, the method has the advantages of little investment, low energy dissipation, high material recovery rate, simple operation, small maintenance quantity, reliable running, requiring no ethane refrigerant compressor, and the like.
Description
Technical field
The invention belongs to the lighter hydrocarbons separation technology field, relate in particular to oxygenate conversion and produce alkene and hydrocarbon cracking and produce a kind of separation method in the olefin hydrocarbon.
Background technology
Ethene and propylene are the basic materials of petrochemical complex industry, and the past obtains by the steam cracking or the catalytic pyrolysis of hydrocarbon always.Under situation about being becoming tight oil supply day, it is the process of raw material production low-carbon alkene with methyl alcohol, ethanol particularly that people have developed with oxide compound.Alcohols can so just have been avoided the use petroleum resources with the synthetic gas production of Sweet natural gas or coal.
The product of oxygenate conversion process is formed similar with the pyrolyzer outlet product composition of hydrocarbon cracking system ethene, all is light gas such as hydrogen, nitrogen and lighter hydrocarbons, and promptly C1 is to stable hydrocarbon and the unsaturated hydrocarbons of C5 or C6.This mixture separation to be become various high purity products, need a very complicated separation process.
In the sepn process of conventional hydrocarbon-based cracking ethylene preparation, generally adopt deep cooling separating method.Typical separation process is broadly divided into three major types, promptly at first removes sequence flow, front-end deethanization flow process and the predepropanization process of methane.Chinese patent ZL 921 00471.0 has proposed the different precut flow process of a kind of and above-mentioned three kinds of flow processs, and first separator of this flow process is the non-clear Cutting Tap of C-2-fraction.That a kind of flow process all needs deep cooling for separation of methane, hydrogen and C2 hydrocarbon, and the cold of multiple different size all need be provided by propylene compressor and ethylene compressor, for example needs the ethene refrigerant condenser that-100 ℃ cold is provided.Also need methane compressor for low-pressure methane removing cold about-135 ℃ is provided.Except the refrigerant condenser system of complexity, also need the ice chest equipment of precise structure, make low temperature separation process flow process complexity, investment greatly.
U.O.P. company has developed a process of producing ethene for fear of the shortcoming of above-mentioned low temperature separation process flow process: " PROCESS FOR PRODUCING ETHYLENE " WO 01/25174.The principal feature of this method is:
Adopt the front-end deethanization flow process, reduce the inlet amount of demethanizing tower.
Therefore improve the temperature of demethanizer column overhead, avoided adopting the ethene cold, but contained the ethene about 15% in the demethanizer column overhead.
In order to reclaim the ethene in the demethanizer column overhead gas, this gas is sent into transformation absorption facility, separation of methane, hydrogen and ethene are in the ethene Returning oxidation reactor outlet material that reclaims.
This patent specification claims that this flow process is similar to the tripping device of the naphtha cracking of routine, can reach 99.5% ethylene recovery rate, and the concentration of ethene can reach more than 99.5% in the ethylene product.This separation method facility investment is lower, but owing to adopted pressure swing adsorption, schedule of operation is complicated, and the system maintenance work amount is bigger.
United States Patent (USP) U.S.P.5,326,929 have proposed a kind of method with solvent absorbing separation of hydrogen, methane and carbon two components.The main flow process of this method is: charging enters a demethanizing absorption tower that intercooling and reboiler are arranged, this tower uses the C5 from methane absorber to do solvent absorbing carbon two and more heavy constituent, tower top outlet gas is methane hydrogen and carbon two and the solvent carried secretly, and the tower still is the solvent that has absorbed carbon two, carbon three.Demethanizing absorption tower overhead gas enters methane absorber, and with the solvent absorbing methane and the carbon two of revivifier outlet, tower top outlet gas is hydrogen product.The solvent that has absorbed methane and more heavy constituent goes to the demethanizing absorption tower from the tower still of methane absorber.The still liquid on demethanizing absorption tower is the solvent that has absorbed a large amount of ethylene, propylenes, must go revivifier regeneration.Carbon two, carbon three that revivifier parses remove deethanizing column, and the regenerated solvent cycle is removed methane absorber.Though this method has been avoided multistage ethene refrigerant condenser and ice chest, the molecule number of required solvent charging ethene and propylene molecules is no better than counted sum.The circulation thermal regeneration of so a large amount of solvents, cooling and absorbing again, energy expenditure is big to be conspicuous.
Chinese patent 200710044193.0 has been developed one and has not been used deep cooling and low temperature demethanizing rectifying tower, only uses the sepn process of propylene refrigerant and one-level inferior grade ethene refrigerant.The principal feature of this method is: with a rectifying tower that is called the precut tower C-2-fraction is carried out non-clear cutting, overhead product enters an absorption tower after cooling, the absorption agent of forming with the mixture of carbon three or carbon four or carbon five or its hydro carbons separates carbon one and carbon two wherein, light gas is discharged by the top, absorption tower, bottom product returns the precut tower, and separate no independent solvent reclamation equipment what precut tower and in succession rectifying tower progressively carried out solvent and other components.This process investment is less, energy consumption is lower, but still needs propylene refrigerant condenser and a single-stage ethene refrigerant condenser, and two refrigerant condenser systems are still arranged.
Summary of the invention
Purpose of the present invention is exactly the separation method that the lower hydrocarbon containing light gas that a kind of less investment, energy consumption is low, material recovery rate is high, simple to operate rectifying combines with solvent absorbing is provided in order to overcome the defective that above-mentioned prior art exists.
Purpose of the present invention can be achieved through the following technical solutions: the separation method of the lower hydrocarbon containing light gas that a kind of rectifying combines with solvent absorbing is characterized in that this method may further comprise the steps:
(1). deliver to the precut tower after will being cooled to 10 ℃～-37 ℃ through pretreated reactor outlet gas, this column overhead product comprises methane, hydrogen and other light gas, part C-2-fraction and the small amount of carbon three that balances each other, and tower still product is all the other carbon two and more heavy constituent;
(2). precut tower exit gas is delivered to an absorption tower, separate wherein carbon one and carbon two with carbon three or carbon four or carbon five or carbon six or its hydrocarbon mixture as absorption agent, the absorption tower overhead product comprises methane, hydrogen and other light gas and the small amount of carbon two and the absorption agent that balance each other, and tower still product is carbon two above components and a spot of hydrogen, methane;
(3). the bottom product on absorption tower is delivered to the precut tower, further absorbs C-2-fraction and removes methane and more deliver to the clear cutting that deethanizing column carries out carbon two and carbon three behind the light constituent at this tower; Deethanizer overhead obtains C-2-fraction, goes ethylene rectification tower to separate and obtains ethene and ethane, and tower still product is carbon three and more heavy constituent; As if containing acetylene in the charging that enters the precut tower, then the deethanizer overhead product removes acetylene earlier and enters ethylene rectification tower again, is purified to needed mass concentration;
Absorption tower described in the step (2) is a separator that a plurality of equilibrium stages are arranged, and this separator is provided with mass transfer and the interchanger that conducts heat and carry out simultaneously at cat head or any one equilibrium stage.
Pre-treatment described in the step (1) is for to be pressurized to reactor outlet gas 2.0～4.0MPa, to remove sour gas and moisture.
Pre-treatment described in the step (1) is for entering high pressure depropanizer with reactor outlet gas after the overdraft cooling removes sour gas and drying, the high pressure depropanizer overhead gas removes the precut tower or be introduced into to remove the precut tower again after acetylene hydrogenation reactor removes alkynes after further being forced into 2.0～4.0MPa.
Precut tower described in the step (1) is the non-clear cutting rectifying tower of C-2-fraction, and the cat head C-2-fraction can account for 5%～70% of feed carbon two; Described other light gas comprise nitrogen, oxygen.
Its top of precut tower described in the step (1) is provided with the interchanger that can carry out heat and mass transfer simultaneously.
Adopt with the propylene on absorption tower described in the step (2) is the absorption agent of major ingredient, and the discharging of deethanizing Tata still is divided into two, and a part is carried out separating of carbon three and carbon four as the charging of depropanizing tower or propylene rectification tower; Another part is cooled to be higher than-65 ℃, and preferred temperature is to be cooled to be higher than-40 ℃, after deliver to the absorption tower as absorption agent.
Adopt with propane on absorption tower described in the step (2) is the absorption agent of major ingredient, the discharging of propylene rectification tower tower still is divided into two, divide and carry out separating of carbon four and carbon five as the charging of debutanizing tower, another part is through being cooled to be higher than-65 ℃, a preferred temperature part is sent the battery limit (BL) as the propane product, another part is cooled to be higher than-65 ℃, and preferred temperature is to be cooled to be higher than-40 ℃, after deliver to the absorption tower as absorption agent.
Adopt with carbon four on absorption tower described in the step (2) is the absorption agent of major ingredient, and the discharging of depropanizing Tata still is divided into two, and a degree is to be cooled to be higher than-40 ℃, after deliver to the absorption tower as absorption agent.
Absorption tower described in the step (2) is adopted with carbon five and is more recombinated and is divided into absorption agent, the discharging of debutylize Tata still is divided into two, a part divides finished product to send the battery limit (BL) as the carbon quintet, another part is through being cooled to be higher than-65 ℃, preferred temperature is to be cooled to be higher than-40 ℃, after deliver to the absorption tower as absorption agent.
Compared with prior art, Chinese patent 200710044193.0 required ethene colds are mainly used in the cooling of oil-absorption tower gas phase and liquid phase feeding.Absorb solute at absorption agent, can emit heat when mainly being carbon two components in the gas phase.When oil-absorption tower was the absorption tower of the frozen-free device of a routine and water cooler, liberated heat raise gas-liquid phase temperature and carbon two components and absorbent contents in the exit gas of absorption tower is rolled up.Therefore Chinese patent 200710044193.0 adopts the method that reduces gas-liquid phase inlet temperature to reduce the temperature of exit gas to reduce carbon two component concentrations wherein.Though the load of required ethene cold is very little, when being 300,000 tons/year, ethylene yield only needs the single-stage ethene refrigerant condenser of a shaft power less than 150KW.But so little ethylene compressor still needs higher investment cost and a large amount of operation and safeguards the manpower of a refrigerant condenser system.Therefore the ethylene compressor that if can cancel such low capacity remains great value.
The present invention adopt absorption agent be absorbed the condition that logistics contacts, temperature has raise under cool off the method for this system, reach the purpose of this system of cooling under higher temperature conditions, so just can replace the ethene cryogen with propylene refrigerant, it is essential that the ethene refrigerant condenser is no longer become.
The present invention is one can not use ethene cold and the method for separating the lower carbon number hydrocarbons that contains light gas that does not have low temperature demethanizing rectifying tower, adopts that ethylene content can be greater than 99.95% in the ethylene product that this method obtains, and the ethylene recovery rate can be greater than 99.6%.
Description of drawings
Fig. 1 is the schema of absorption agent for the present invention with carbon three;
Fig. 2 is the schema of absorption agent for the present invention with carbon four;
Fig. 3 is the schema of absorption agent for the present invention with carbon five;
Fig. 4 is the schema of absorption agent with propane for the present invention.
Embodiment
The present invention has developed a kind of method that does not have deep cooling ice chest and low temperature demethanizing rectifying tower, do not have to contain separating of ethene refrigerant condenser the lower carbon number hydrocarbons of light gas, this method less investment, energy consumption is low, material recovery rate is high, simple to operate, maintenance is little, reliable.
The present invention can adopt reactor outlet through overdraft, remove sour gas and exsiccant charging, also above-mentioned material can be entered through after removing propane again.Divide gas-liquid two-phase to enter after imported raw material is cooled to 10 ℃ to-37 ℃ and give Cutting Tap.This tower is the non-clear cutting rectifying tower of C-2-fraction, overhead product comprises methane, hydrogen and presumable other light gas (as a spot of nitrogen, oxygen), part C-2-fraction and the small amount of carbon three that balances each other, and the cat head C-2-fraction can account for 5% to 70% of feed carbon two; Tower still product is all the other carbon two and all more heavy constituent.The overhead product of precut tower goes to an absorption tower, with through the mixture of overcooled carbon three or carbon four or carbon five or carbon six or these hydro carbons as absorption agent, C2 hydrocarbon class in the precut column overhead product is absorbed, and light gas is discharged by the top, absorption tower, and still liquid returns the precut tower.Contain a small amount of absorption agent in the tower top outlet gas on absorption tower, the temperature of ratio in charging of its quantity and light gas, absorption tower inlet feed is relevant with absorption agent character.Under reasonable process conditions, when the absorption agent composition was mainly carbon three, carbon three content in the exit gas were generally in 2% to 7% scope.Further reduce the content or the purifying hydrogen of hydrogen of carbon three as need, the separation facilities that the tail gas of above-mentioned cooler condenser can be entered again other, for example transformation absorption or membrane sepn but be not limited to this two kinds of separation facilities.When being carbon four or carbon five as absorption agent, then the content of absorption agent in exit gas is generally respectively less than 1.8% or 1.0%.
The tower still product of precut tower is delivered to the clear cutting that deethanizing column carries out carbon two and carbon three, and the C-2-fraction that deethanizer overhead obtains enters ethylene rectification tower and is separated into ethene and ethane; Tower still product is carbon three and more heavy constituent.As if containing acetylene in the charging that enters the precut tower, then the deethanizer overhead product need remove acetylene earlier and enter ethylene rectification tower again.
If adopt with carbon three on the absorption tower is the absorption agent of major ingredient, the (see figure 1) that the discharging of deethanizing Tata still can be divided into two, a part is carried out separating of carbon three and carbon four as the charging of depropanizing tower; Another part is delivered to the absorption tower as absorption agent after pump pressurization and cooling.The amount of absorption agent can be 5%～90% of a deethanizing column carbon still load.The cat head discharging of depropanizing tower is a carbon three, enters propylene rectification tower and is separated into propylene and propane.Exceed carbon three finished products and fill the alkynes content of being permitted if contain in carbon three components, then should remove alkynes earlier and adopt rectificating method to separate each component again; Tower still product is carbon four and more heavy constituent.
If adopt with carbon four on the absorption tower is the absorption agent of major ingredient, the (see figure 2) that the discharging of depropanizing Tata still can be divided into two, a part is carried out separating of carbon four and carbon five as the charging of debutanizing tower; Another part is delivered to the absorption tower as absorption agent after pump pressurization and cooling.The amount of absorption agent can be 20%～95% of a carbon still load.If the low excessively driving overlong time that makes the essential absorption agent of accumulation of C 4 fraction content in the charging then can be at the disposable injection carbon four of depropanizing Tata still as the absorption agent that recycles.
If adopting with carbon five and more recombinate, the absorption tower is divided into absorption agent, the (see figure 3) that the discharging of debutylize Tata still can be divided into two, and a part divides finished product to send the battery limit (BL) as the carbon quintet; Another part is delivered to the absorption tower as absorption agent after pump pressurization and cooling.The amount of absorption agent can be 30～98% of a carbon still load.If the carbon quintet divides content the low excessively driving overlong time that makes the essential absorption agent of accumulation in the charging, then can be at the disposable injection carbon five of debutylize Tata still as the absorption agent that recycles.
If charging does not contain carbon four and more heavy constituent through depropanizing tower before entering the precut tower, its separation process is seen Fig. 4.Reactor outlet gas enters high pressure depropanizer behind overdraft, washing, alkali cleaning and drying and dehydrating.The high pressure depropanizer overhead gas further is pressurized to enters acetylene hydrogenation reactor behind 2.0～4.0MPa and remove alkynes; Perhaps acetylene hydrogenation reactor is arranged at the deethanizer overhead outlet, directly cools off the high pressure depropanizer overhead gas and obtain gas-liquid two-phase.Gas phase enters the precut tower, and liquid phase is divided into two, and a part is as the backflow of high pressure depropanizer, and a part is as the charging of precut tower.The overhead product of precut tower is delivered to the absorption tower, and this tower, absorbs the C2 hydrocarbon class in the precut column overhead product get off as absorption agent with carbon three, and light gas is discharged by the top; Absorb Tata still product and return the precut tower as charging.The tower still product of precut tower is delivered to the clear cutting that deethanizing column carries out carbon two and carbon three, and cat head obtains C-2-fraction and removes ethylene rectification tower, obtains ethene and ethane through separation, and tower still product is a carbon three.If adopting with the propylene is carbon three absorption agents of major ingredient, the tower still discharging of deethanizing column is divided into two, part still liquid is delivered to the absorption tower as absorption agent after pump pressurization and cooling, and part is sent propylene rectification tower.If adopt with propane be major ingredient carbon three absorption agent (see figure 4)s then the tower still discharging of deethanizing column all send propylene rectification tower, be separated into propylene and propane at this tower, again propane is divided into two, a part is sent the battery limit (BL) as the propane product, and rest part is delivered to the absorption tower as absorption agent after pump pressurization and cooling.
No matter which kind of absorption agent the absorption tower adopts, absorb cat head vent gas body and all can pass through decompressor or reducing valve and interchanger, reduce pressure and be heated to satisfactory pressure and temperature after send.No matter which kind of absorption agent the absorption tower adopts, absorb cat head vent gas body and all can enter other separation facilities as required.
Adopt said process, contained C-2-fraction is greater than 99.8% of charging in the still liquid at the bottom of the precut tower, and C3 fraction has very high material recovery rate greater than 99.5% of charging.
Second advantage of the present invention is that energy consumption is low.Separation of methane of the present invention, hydrogen and C-2-fraction are finished by two steps.The first step usefulness precut tower separates 30%～95% carbon two and methane, hydrogen.Second step with solvent absorbing carbon two, reached the separating fully of methane hydrogen of carbon two and tower top outlet on the absorption tower.The charging on absorption tower is cooled to temperature with cryogen and is higher than-65 ℃, and preferred temperature is to be cooled to be higher than-40 ℃.Since carbon two before entering the absorption tower major part be removed, the quantity of required solvent is wanted much less with respect to the solvent absorbing separation method that other C-2-fractions all enter the absorption tower, and the regeneration of solvent realizes there is not independent reclaim equiment at precut tower and rectifying tower in succession.
When U.S.P.5326929 adopts C5 to make solvent, when ethylene content in the charging is 4763.3 lb mole/hr, need solvent 5651.8 lb mole/h, the ratio of solvent and carbon two is 1.186.This method regenerated solvent under greater than the pressure of 3.2mpa, regeneration temperature is very high, may be up to 150 ℃.And then this solvent is cooled to-50 ℃ of laggard methane absorbers.So a large amount of solvents heats refrigeration cycle more earlier, and energy expenditure is big to be conspicuous.But the advantage of this method is to be applicable to the splitting gas composition of various hydrocarbon cracking system ethylene units and not have cryogenic system.
Embodiment 1
Flow process is seen Fig. 3, and certain reactor outlet gas enters sepn process through overdraft, washing, alkali cleaning, after removing methyl alcohol and drying and dehydrating.This gas S100 is cooled to enter about 10 ℃ flash tank V101 through feed cooler E101 to carry out gas-liquid and is separated.Gas-liquid respectively by further cooling behind precut tower feed cooler E102 and the E103, enters precut tower T101 mutually then.The overhead product S308 of precut tower T101 directly enters an absorption tower T102 that overhead condenser is arranged without further cooling, and this condenser adopts propylene refrigerant.It is that the absorption agent S327 of major ingredient absorbs the carbon two in the charging that absorption tower T102 adopts with carbon five, and S327 is cooled to-37 ℃ with propylene refrigerant.Precut tower T101 tower still discharging S311 is carbon two, carbon three and heavier product, directly goes deethanizing column T201 to carry out separating of carbon two and carbon three.Deethanizing column T201 overhead product C-2-fraction removes ethylene rectification tower after removing acetylene and ethylene-ethane is separated; Bottom product goes depropanizing tower T202 to separate carbon three and carbon four.The depropanizing tower overhead product is C3 fraction, further obtains propylene product after the processing; Tower still product removes debutanizing tower T203.The debutanizing tower overhead product is a carbon four, and tower kettle product is a carbon five.C5 fraction is divided into two, and a part is sent the battery limit (BL) for carbon five products; Part S327 delivers to the absorption tower as absorption agent after pump pressurization and cooling.
After listed logistics data passed through precut tower and light gas such as absorption tower separation of methane, hydrogen as can be known by table, the ethene in the charging only lost 0.0940kgmol, accounts for 0.00698% of charging, and solvent loss 0.5408kgmol accounts for 0.808% of charging.
Table one is the calculation result kgmol/hr of absorption agent with C5
| Form | S100 | S303 | S304 | S308 | S311 | S327 |
| H 2 | 89.2198 | 89.2196 | 2.3414 | 91.5610 | 0 | |
| CH 4 | 105.3869 | 105.0954 | 32.6045 | 137.700 | 0.2897 | |
| C 2H 4 | 1346.834 | 0.0940 | 154.0103 | 154.1042 | 1346.7303 | |
| C 2H 6 | 24.9279 | 0 | 0.1604 | 0.1604 | 24.9303 | |
| C 3H 6 | 871.5141 | 4.633E-4 | 4.633E-4 | 871.514 | ||
| C 3H 8 | 56.243 | 0 | 1.203E-5 | 1.2017E-5 | 56.243 | |
| DME | 11.0136 | 0 | 9.273E-5 | 2.1008E-6 | 11.0137 | |
| C 4H 8 | 46.1926 | 6.495E-3 | 0.7502 | 7.5219E-3 | 46.9354 | 0.7492 |
| IC 4H 10 | 115.1430 | 7.018E-3 | 0.6140 | 7.887E-3 | 115.7490 | 0.6131 |
| NC 4H 10 | 8.25 | 3.173E-3 | 0.3899 | 5.3901E-3 | 8.6345 | 0.3877 |
| C 5H 10 | 40.427 | 0.3601 | 208.8943 | 0.4537 | 248.7155 | 208.8007 |
| C 5H 12 | 26.510 | 0.1807 | 139.4998 | 0.2313 | 165.9312 | 139.4492 |
| Total flux | 2741.6619 | 194.9664 | 539.2654 | 384.2318 | 2896.6865 | 350.0 |
Embodiment 2
Flow process is seen Fig. 2, and certain reactor outlet gas enters sepn process through overdraft, washing, alkali cleaning, after removing methyl alcohol and drying and dehydrating.This gas S100 is cooled to enter about 10 ℃ flash tank V101 through feed cooler E101 to carry out gas-liquid and is separated.Gas-liquid is mutually respectively by entering precut tower T101 behind precut tower feed cooler E102 and the E103.The overhead product S308 of precut tower T101 comprises whole light gas and accounts for the ethene of charging about 11%, enters absorption tower T102.It is that the absorption agent S327 of major ingredient absorbs the carbon two in the charging that absorption tower T102 adopts with carbon four.Precut tower T101 tower still discharging S311 is carbon two, carbon three and heavier product, directly goes deethanizing column T201 to carry out separating of carbon two and carbon three.Deethanizing column T201 overhead product is a C-2-fraction, goes ethylene rectification tower to be separated into ethylene-ethane after removing acetylene; Bottom product goes depropanizing tower to separate carbon three and carbon four.Depropanizing tower T202 overhead product is C3 fraction, further obtains propylene product after the processing; Tower still product is carbon four and more heavy constituent, and this product is divided into two, and a part goes debutanizing tower T203 as charging, and another part is delivered to the absorption tower as absorption agent after pump pressurization and cooling.The debutanizing tower overhead product is carbon four S503, and tower kettle product is that carbon five products are sent the battery limit (BL).
After listed logistics data passed through precut tower and light gas such as absorption tower separation of methane, hydrogen as can be known by table, the ethylene loss 0.1892kgmol in the tail gas only accounted for 0.014% of charging ethene; Carbon four in the tail gas adds up to 2.5759kgmol, accounts for 1.5% of feed carbon four.Absorption tower contained ethene in the circulation fluid S304 of precut tower equals 11% of charging ethene.
Table two is the calculation result kgmol/hr of absorption agent with C4
| Form | S100 | S303 | S304 | S308 | S311 | S327 |
| H 2 | 89.2198 | 89.2196 | 2.9114 | 92.1087 | 0 | |
| CH 4 | 105.3869 | 105.0271 | 34.8735 | 139.9007 | 0.2901 | |
| C 2H 4 | 1346.834 | 0.1892 | 147.9895 | 148.1787 | 1346.3115 | |
| C 2H 6 | 24.9279 | 0 | 0.2185 | 0.2185 | 24.9772 | |
| C 3H 6 | 871.5141 | 5.57E-4 | 0.0149 | 2.86E-3 | 871.5273 | 0.0127 |
| C 3H 8 | 56.243 | 3.30E-4 | 8.72E-3 | 4.16E-4 | 56.2512 | 8.66E-3 |
| DME | 11.0136 | 0.0139 | 0.7009 | 0.0161 | 11.6989 | 0.6987 |
| C 4H 8 | 46.1926 | 0.5998 | 69.3023 | 0.6917 | 114.3562 | 69.3229 |
| IC 4H 10 | 115.1430 | 1.8802 | 167.5752 | 2.1066 | 279.1339 | 167.8349 |
| NC 4H 10 | 8.25 | 0.0959 | 12.7419 | 0.1692 | 20.7694 | 12.6761 |
| C 5H 10 | 40.427 | 0.1157 | 66.6151 | 0.1467 | 108.1273 | 66.1871 |
| C 5H 12 | 26.510 | 0.0573 | 43.4842 | 0.0734 | 70.7016 | 43.259 |
| Total flux | 2741.6619 | 197.179 | 546.4362 | 383.6146 | 2904.1448 | 360.0 |
Embodiment 3
Flow process is seen Fig. 4, and certain reactor outlet gas S100 enters high pressure depropanizer T202A behind overdraft, washing, alkali cleaning and drying and dehydrating.High depropanizing tower T202A overhead gas further is forced into and obtains gas-liquid two-phase after material behind the 3.6Mpa is cooled to 2 ℃, and gas-liquid is further cooling respectively mutually.Gas phase enters precut tower T101, and liquid phase is divided into two, and a part is as the backflow of high pressure depropanizer T202A, and a part is as precut tower T101 charging.The overhead product S308 of precut tower T101 delivers to absorption tower T102 after cooling, it is the absorption agent of main component that this tower adopts with propane, and the C2 hydrocarbon class in the precut column overhead product is absorbed, and methane hydrogen S313 discharges from the tower item.Absorption tower T102 tower still product S304 returns precut tower T101 as charging.The tower still product S311 of precut tower T101 delivers to the clear cutting that deethanizing column T201 carries out carbon two and carbon three, and cat head obtains C-2-fraction and delivers to ethylene rectification tower D402 and be separated into ethene and ethane; Tower still product is a carbon three, delivers to propylene rectification tower D405 after carbon three is removed propine.The cat head propylene product of propylene rectification tower is sent the battery limit (BL); A tower still propane part is delivered to the absorption tower as absorption agent S327, and rest part is sent the battery limit (BL) as product.
After listed logistics data passed through precut tower and light gas such as absorption tower separation of methane, hydrogen as can be known by table, the ethylene loss 0.1105kgmol in the tail gas only accounted for 0.0082% of charging ethene; Propylene in the tail gas adds up to 0.7927kgmol, accounts for 0.091% of charging propylene.Absorption tower contained ethene in the circulation fluid S304 of precut tower equals 11% of charging ethene.
Table three is the calculation result kgmol/hr of absorption agent major ingredient with C3H8
| Form | S100 | S303 | S304 | S308 | S311 | S327 |
| H 2 | 89.2198 | 89.2176 | 3.5812 | 92.7988 | ||
| CH 4 | 105.3869 | 105.1382 | 42.7717 | 147.9098 | 0.2463 | |
| C 2H 4 | 1346.834 | 0.1105 | 141.7327 | 141.8432 | 1345.9768 | |
| C 2H 6 | 24.9279 | 0 | 0.1399 | 0.1399 | 24.8716 | |
| C 3H 6 | 871.5141 | 0.7927 | 175833 | 0.8560 | 641.9276 | 17.520 |
| C 3H 8 | 56.243 | 11.3791 | 333.612 | 12.3715 | 358.6873 | 332.6197 |
| DME | 11.0136 | 1.3858 | 77.7085 | 1.5937 | 80.2973 | 77.5007 |
| C 4H 8 | 46.1926 | 0.0168 | 2.1337 | 0.0191 | 2.3569 | 2.1315 |
| IC 4H 10 | 115.1430 | 0.0762 | 8.1173 | 0.0866 | 8.8634 | 8.1069 |
| NC 4H 10 | 8.25 | 8.537e-4 | 0.1217 | 1.4896e-3 | 01333 | 0.1211 |
| C 5H 10 | 40.427 | 0 | 6.5577e-5 | 0 | 7.357e-5 | 6.55e-5 |
| C 5H 12 | 26.510 | 0 | 3.26e6-4 | 0 | 4.2366e-6 | 3.768e-6 |
| Total flux | 2741.6619 | 208.1179 | 627.5021 | 397.3199 | 2463.3625 | 438.00 |
Claims (9)
1. the separation method of the lower hydrocarbon containing light gas that combines with solvent absorbing of a rectifying is characterized in that this method may further comprise the steps:
(1). deliver to the precut tower after will being cooled to 10 ℃～-37 ℃ through pretreated reactor outlet gas, this column overhead product comprises methane, hydrogen and other light gas, part C-2-fraction and the small amount of carbon three that balances each other, tower still product are all the other carbon two and more heavy constituent;
(2). precut tower exit gas is delivered to an absorption tower, separate wherein carbon one and carbon two with carbon three or carbon four or carbon five or carbon six or its hydrocarbon mixture as absorption agent, the absorption tower overhead product comprises methane, hydrogen and other light gas and the small amount of carbon two and the absorption agent that balance each other, and tower still product is carbon two above components and a spot of hydrogen, methane;
(3). the bottom product on absorption tower is delivered to the precut tower, further absorbs C-2-fraction and removes methane and more deliver to the clear cutting that deethanizing column carries out carbon two and carbon three behind the light constituent at this tower; Deethanizer overhead obtains C-2-fraction, goes ethylene rectification tower to separate and obtains ethene and ethane, and tower still product is carbon three and more heavy constituent; As if containing acetylene in the charging that enters the precut tower, then the deethanizer overhead product removes acetylene earlier and enters ethylene rectification tower again, is purified to needed mass concentration;
Absorption tower described in the step (2) is a separator that a plurality of equilibrium stages are arranged, and this separator is provided with mass transfer and the interchanger that conducts heat and carry out simultaneously at cat head or any one equilibrium stage.
2. the separation method of the lower hydrocarbon containing light gas that a kind of rectifying according to claim 1 combines with solvent absorbing, it is characterized in that the pre-treatment described in the step (1) is for to be pressurized to reactor outlet gas 2.0～4.0MPa, to remove sour gas and moisture.
3. the separation method of the lower hydrocarbon containing light gas that a kind of rectifying according to claim 1 combines with solvent absorbing, it is characterized in that, pre-treatment described in the step (1) is for entering high pressure depropanizer with reactor outlet gas after the overdraft cooling removes sour gas and drying, the high pressure depropanizer overhead gas removes the precut tower or be introduced into to remove the precut tower again after acetylene hydrogenation reactor removes alkynes after further being forced into 2.0～4.0MPa.
4. the separation method of the lower hydrocarbon containing light gas that a kind of rectifying according to claim 1 combines with solvent absorbing, it is characterized in that, precut tower described in the step (1) is the non-clear cutting rectifying tower of C-2-fraction, and the cat head C-2-fraction can account for 5%～70% of feed carbon two; Described other light gas comprise nitrogen, oxygen.
5. the separation method of the lower hydrocarbon containing light gas that a kind of rectifying according to claim 1 combines with solvent absorbing is characterized in that, its top of precut tower described in the step (1) is provided with the interchanger that can carry out heat and mass transfer simultaneously.
6. the separation method of the lower hydrocarbon containing light gas that a kind of rectifying according to claim 1 combines with solvent absorbing, it is characterized in that, adopt with the propylene on absorption tower described in the step (2) is the absorption agent of major ingredient, the discharging of deethanizing Tata still is divided into two, and a part is carried out separating of carbon three and carbon four as the charging of depropanizing tower or propylene rectification tower; Another part is cooled to be higher than-65 ℃, and preferred temperature is to be cooled to be higher than-40 ℃, after deliver to the absorption tower as absorption agent.
7. the separation method of the lower hydrocarbon containing light gas that a kind of rectifying according to claim 1 combines with solvent absorbing, it is characterized in that, adopt with propane on described absorption tower is the absorption agent of major ingredient, the discharging of propylene rectification tower tower still is divided into two, a part is sent the battery limit (BL) as the propane product, another part is cooled to be higher than-65 ℃, and preferred temperature is to be cooled to be higher than-40 ℃, after deliver to the absorption tower as absorption agent.
8. the separation method of the lower hydrocarbon containing light gas that a kind of rectifying according to claim 1 combines with solvent absorbing, it is characterized in that, adopt with carbon four on absorption tower described in the step (2) is the absorption agent of major ingredient, the discharging of depropanizing Tata still is divided into two, a part is carried out separating of carbon four and carbon five as the charging of debutanizing tower, another part is through being cooled to be higher than-65 ℃, and preferred temperature is to be cooled to be higher than-40 ℃, after deliver to the absorption tower as absorption agent.
9. the separation method of the lower hydrocarbon containing light gas that a kind of rectifying according to claim 1 combines with solvent absorbing, it is characterized in that, described absorption tower is adopted with carbon five and is more recombinated and is divided into absorption agent, the discharging of debutylize Tata still is divided into two, a part divides finished product to send the battery limit (BL) as the carbon quintet, another part is through being cooled to be higher than-65 ℃, and preferred temperature is to be cooled to be higher than-40 ℃, after deliver to the absorption tower as absorption agent.
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