CN116870663A - Amine liquid purification and regeneration system and method - Google Patents

Amine liquid purification and regeneration system and method Download PDF

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Publication number
CN116870663A
CN116870663A CN202310981153.8A CN202310981153A CN116870663A CN 116870663 A CN116870663 A CN 116870663A CN 202310981153 A CN202310981153 A CN 202310981153A CN 116870663 A CN116870663 A CN 116870663A
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China
Prior art keywords
amine liquid
vacuum
amine
tank
liquid
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CN202310981153.8A
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Chinese (zh)
Inventor
黄莺
林贤莉
解政鼎
马明燕
苏燕兵
林海涛
孙长庚
刘建国
孟令冰
唐硕
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China National Petroleum Corp
China Huanqiu Contracting and Engineering Corp
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China National Petroleum Corp
China Huanqiu Contracting and Engineering Corp
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Priority to CN202310981153.8A priority Critical patent/CN116870663A/en
Publication of CN116870663A publication Critical patent/CN116870663A/en
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1425—Regeneration of liquid absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/14—Evaporating with heated gases or vapours or liquids in contact with the liquid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/26—Multiple-effect evaporating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/30—Accessories for evaporators ; Constructional details thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0033—Other features
    • B01D5/0045—Vacuum condensation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
    • B01D5/006—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with evaporation or distillation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456—Removing acid components
    • B01D53/1475—Removing carbon dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1493—Selection of liquid materials for use as absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
    • B01D2252/20—Organic absorbents
    • B01D2252/204—Amines

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Gas Separation By Absorption (AREA)
  • Degasification And Air Bubble Elimination (AREA)

Abstract

The invention discloses an amine liquid purifying and regenerating system and method. The system comprises: an amine liquid supply pipeline to be purified, a vacuum stripping evaporation tank, a vacuum condenser, a vacuumizing unit and an amine liquid tank; the vacuum stripping evaporation tank is provided with an amine liquid inlet to be purified, a recovered gas outlet and a discharged liquid outlet; the to-be-purified amine liquid incoming pipeline is connected with the to-be-purified amine liquid inlet; an alkali liquor feeding port is arranged on the amine liquid incoming pipeline to be purified; the recycling gas outlet is positioned at the top of the vacuum stripping evaporation tank and is connected with the amine liquid tank, and the vacuum condenser is arranged on the connecting pipeline; the saidThe discharged liquid outlet is positioned at the bottom of the vacuum stripping evaporation tank; the vacuumizing unit is communicated with the top of the vacuum condenser or the top of the amine liquid tank. The system has the advantages of low investment, less waste liquid discharge, high amine recovery rate, thorough heat stable salt removal and easy popularization and application, thereby ensuring CO 2 The trapping system is stable for a long time and operates at low cost.

Description

Amine liquid purification and regeneration system and method
Technical Field
The present invention relates to CO 2 The technical field of trapping, in particular to an amine liquid purifying and regenerating system and method.
Background
Post-combustion CO currently in wide and mature industrial application 2 The trapping technology is a chemical absorption method using an organic amine liquid as an absorbent. In the operation process of the amine liquid, a plurality of pollutants can appear to influence the operation of the system, including macromolecular substances such as particles, oil, grease, surfactant and the like, inorganic salts, heat-stable amine salts and the like. These contaminants can cause the following hazards: the particles are easy to generate high shearing force in the solvent circulation process, so that the abrasion corrosion of the system is caused; the oil, fat and surface active substances are easy to cause foaming of the solvent, and cause absorption rate of the solventDecrease and increase in solvent escape loss; cl of inorganic salts such as NaCl - High corrosiveness to equipment pipelines; organic amine to strong acid (acid ratio CO) 2 Strong) amine salts, abbreviated as thermostable salts, generated by the reaction, which are derived from oxidative degradation of feed gas, system makeup water or amine liquid. Accumulation of heat stable salts reduces the absorption capacity of the solution, resulting in foaming of the solution, increased loss of solution, and increased corrosiveness.
The amine liquid purifying system has the function of removing pollutants in the amine liquid, thereby ensuring the long-period stable operation of the acid gas absorbing and purifying process. The currently common amine liquid purification methods include heating distillation, electrodialysis technology and ion exchange technology. The heating distillation method has the problems of high amine liquid loss, high waste amine liquid disposal cost, high energy consumption and the like, and is gradually eliminated. Compared with the heating distillation method, the ion exchange technology has the advantages of low energy consumption and high amine liquid recovery rate, but has the following defects: the amine liquid from the regeneration tower often contains incompletely desorbed CO 2 The formed anions cause that a great deal of anions are wasted in the ion exchange process, so that the trapping rate of CO2 is reduced, the service life of the resin is greatly reduced, and the purification cost of amine liquid is increased; in addition, the alkali liquor and the desalting water used in the regenerated resin have large quantity, the generated waste liquid has large quantity and is difficult to treat, and the concentration water content of the purified amine liquid is increased, so that the water balance of an absorption system is easy to damage. Compared with the ion exchange technology, the electrodialysis technology has no problems of bringing water into an amine liquid system and the like, and no subsequent treatment problem of alkali-containing wastewater generated by regenerated resin, but the electrodialysis technology also has obvious defects, particularly the technology is still immature, the recovery rate of the amine liquid is only 96-98%, the membrane assembly is easy to pollute, the service life is short, the investment cost is high, the electricity consumption is high, the COD content caused by the amine liquid carried in the generated strong brine is high, and a certain difficulty is brought to the subsequent water treatment. In addition, both ion exchange and electrodialysis techniques require three or more stages of sophisticated filtration systems prior to the main apparatus to protect the resin and membrane modules, increasing capital and labor costs for cleaning and replacing the filters.
Disclosure of Invention
The invention aims to provide a device The seed amine liquid purifying and regenerating system and method has the advantages of low investment, less waste liquid discharge, high amine recovery rate, thorough heat stable salt removal, easy popularization and application, thereby ensuring CO 2 The trapping system is stable for a long time and operates at low cost.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in one aspect, the present invention provides an amine liquid purification and regeneration system, wherein the amine liquid purification and regeneration system comprises:
an amine liquid supply pipeline to be purified, a vacuum stripping evaporation tank, a vacuum condenser, a vacuumizing unit and an amine liquid tank;
the vacuum stripping evaporation tank is provided with an amine liquid inlet to be purified, a recovered gas outlet and a discharged liquid outlet;
the to-be-purified amine liquid supply pipeline is connected with the to-be-purified amine liquid inlet and is used for inputting the to-be-purified amine liquid into the vacuum stripping evaporation tank;
an alkali liquor feeding port is arranged on the to-be-purified amine liquor incoming pipeline and is used for mixing alkali liquor (such as NaOH solution or KOH solution) into the to-be-purified amine liquor, and active amine is released by adding alkali liquor to neutralize acid radical ions of heat stable salt; preferably, the pH value of the mixed alkali liquor is adjusted to be 9-10;
the recycling gas outlet is positioned at the top of the vacuum stripping evaporation tank and is connected with the amine liquid tank, and the vacuum condenser is arranged on the connecting pipeline; condensing the recovered gas obtained by vacuum stripping evaporation in the vacuum stripping evaporation tank through the vacuum condenser, and then taking the condensed gas as recovered amine liquid to enter the amine liquid tank for storage;
The discharge liquid outlet is positioned at the bottom of the vacuum stripping evaporation tank;
the vacuumizing unit is communicated with the top of the vacuum condenser or the amine liquid tank and is used for pumping non-condensable gas in the system and maintaining the vacuum degree required by the system. The main component of the noncondensable gas is N 2 、O 2 、CO 2 And water vapor, can be directly discharged.
The amine liquid to be purified is evaporated into active amine molecules and water vapor molecules in a vacuum stripping evaporation tank through stripping, and then enters a vacuum condenser, and the condensed liquid phase is stored in an amine liquid tank as recovered amine liquid. And the high boiling point impurities containing the heat stable salt and the particulate matters are discharged to the waste liquid treatment device from a bottom discharge liquid outlet of the vacuum stripping evaporation tank, wherein the discharge can be continuous discharge or intermittent discharge.
According to some preferred embodiments of the invention, a heating assembly, such as a heating coil or tube bundle, is provided inside the vacuum stripping evaporator to accelerate the stripping evaporation.
By adjusting the temperature in the vacuum stripping evaporation tank and the gas phase partial pressure of the amine (through the heating component and the vacuumizing unit), the transfer of the amine molecules from the liquid phase to the gas phase is promoted, the yield of active amine is improved, the amine loss of unit product is reduced, and the three-waste emission is reduced. Preferably, the operating pressure of the vacuum stripping evaporation tank is 2-50 kPa, the operating temperature is 100-180 ℃, and the vacuum stripping evaporation tank is determined according to the composition of the amine liquid and the content of the heat stable salt.
The operating pressure of the vacuum condenser is consistent with that of a vacuum stripping evaporation tank connected with the vacuum condenser, and the temperature is the dew point temperature under the corresponding operating pressure. On one hand, the vacuum condenser can liquefy the recovered gas and then send the liquefied gas back to CO by using a pump 2 The trapping system greatly reduces the load of the rear vacuumizing unit on one hand.
According to some preferred schemes of the invention, the vacuum stripping evaporation tank is further provided with a stripping gas inlet for inputting stripping gas into the vacuum stripping evaporation tank and carrying out stripping evaporation on amine liquid to be purified; the stripping gas is selected from nitrogen, air, flue gas, steam, CO 2 At least one of product gas, MVR flash vapor, and the like. The stripping gas is optionally introduced, and the stripping gas inlet is selectively designed according to actual conditions, and may or may not be provided. For example, in one embodiment, only steam is used to heat the coil.
According to some preferred schemes of the invention, a nozzle type gas-liquid distributor connected with the amine liquid inlet to be purified is further arranged in the vacuum stripping evaporation tank, and the escape rate of active amine molecules is improved by increasing the specific surface area of gas-liquid contact through atomization.
According to some preferred embodiments of the present invention, the bottom of the vacuum stripping evaporation tank is a conical bottom, and the effluent outlet is located at the conical bottom.
According to some preferred schemes of the invention, the vacuum condenser is a shell-and-tube heat exchanger, the tube side is a cooling medium, the shell side is connected with a connecting pipeline of the recovered gas outlet and the amine liquid tank and is used for condensing the recovered gas discharged from the top of the vacuum stripping evaporation tank, and the condensate, namely the recovered amine liquid, is pumped by the vacuumizing unit to maintain the required vacuum degree of the system. When the vacuumizing unit is connected with the vacuum condenser, the vacuumizing unit is connected with a shell side of the vacuum condenser.
According to some preferred embodiments of the present invention, wherein the cooling medium is chilled water, circulating water or low-temperature organic refrigerant, in particular according to CO 2 The utility conditions on which the trapping device relies.
According to some preferred embodiments of the present invention, the vacuum stripping and evaporating tank includes a plurality of stages of vacuum stripping and evaporating tanks with pressure gradually decreasing in series; the multistage vacuum stripping evaporation tanks are connected through liquid phase pipelines, recovery gas outlets at the tops of the vacuum stripping evaporation tanks at each stage are all connected with the amine liquid tanks, and the vacuum condensers are all arranged on the connecting pipelines.
When the system of the invention comprises a multi-stage vacuum air extraction and evaporation tank, the liquid phase at the bottom of the tank continuously enters the next stage vacuum air extraction and evaporation tank through a liquid phase pipeline. Preferably, the effluent in the vacuum stripper evaporator of the first stage is intermittently discharged through an effluent outlet, and the effluent in the vacuum stripper evaporators of the other stages is continuously discharged through an effluent outlet.
According to some preferred embodiments of the present invention, the vacuum extraction and evaporation tank includes a primary vacuum extraction and evaporation tank and a secondary vacuum extraction and evaporation tank connected in series, wherein the pressure of the primary vacuum extraction and evaporation tank and the pressure of the secondary vacuum extraction and evaporation tank are gradually reduced;
an amine liquid inlet to be purified of the primary vacuum air extraction and evaporation tank is connected with an amine liquid incoming pipeline to be purified, and a primary vacuum condenser is arranged on a connecting pipeline of a recovered gas outlet and the amine liquid tank;
the primary vacuum extraction and evaporation tank is also provided with an interstage amine liquid outlet which is connected with an amine liquid inlet to be purified of the secondary vacuum extraction and evaporation tank;
and a secondary vacuum condenser is arranged on a connecting pipeline between the recovered gas outlet of the secondary vacuum extraction and evaporation tank and the amine liquid tank.
According to some preferred aspects of the invention, the vacuumizing unit is respectively communicated with the primary vacuum condenser and the secondary vacuum condenser; or the vacuumizing unit is communicated with the top of the amine liquid tank.
According to some preferred aspects of the invention, when the vacuumizing unit is communicated with the vacuum condenser, a silk screen foam remover is arranged at a vacuumizing outlet of the vacuum condenser;
when the vacuumizing unit is communicated with the top of the amine liquid tank, a silk screen foam remover is arranged at the lower side of a vacuumizing outlet at the top of the amine liquid tank; when a vacuum is drawn, gas is drawn from the top outlet and the wire mesh demister is used to capture the gas entrained amine liquid.
According to some preferred aspects of the invention, the vacuumizing unit is a liquid ring type vacuum pump or a vacuum steam ejector. The vacuum degree required by the whole system can be maintained by only pumping out non-condensable gas of the system, so that the non-condensable gas can be connected with a vacuum condenser or communicated with the top of an amine liquid tank. The low-pressure steam condensate generated by the vacuum steam ejector can be converged into the vacuum stripping evaporation tank.
According to some preferred embodiments of the invention, an amine liquid pump is connected to the amine liquid tank.
The amine liquid tank is used for collecting the recovered amine liquid discharged by the vacuum condenser, and is pressurized to 120-150 kPa by the amine liquid pump to return CO 2 Lean liquid tanks or underground tanks of the trapping system.
According to some preferred embodiments of the invention, wherein the amine liquid pump is followed by a filter unit as the feed CO 2 The last stage of protection measures of the trapping system. Preferably, the filter unit may comprise a mechanical filter and an activated carbon filter. Because the particulate matter entrained in the amine liquid has been minimized by the purification of the system described above, the process is superior to conventional techniquesCompared with the filter device arranged in front of the amine liquid purifying system, the impurity amount is greatly reduced, and the maintenance cost of the filter unit is reduced.
According to some preferred embodiments of the invention, the filter unit comprises a mechanical filter, an activated carbon filter and a three-stage filter connected in series with the mechanical filter.
According to some preferred schemes of the invention, the to-be-purified amine liquid incoming pipeline is provided with a pressure reducing valve behind the alkali liquid feeding port, and the to-be-purified amine liquid is mixed with the alkali liquid, then subjected to pressure reduction through the pressure reducing valve and then enters the vacuum air stripping evaporation tank.
According to some preferred schemes of the invention, the amine liquid purifying and regenerating system is further provided with an amine liquid stripping tower in front of the vacuum stripping evaporation tank, the bottom of the amine liquid stripping tower is provided with a water vapor inlet and an amine liquid outlet, and the top of the tower is provided with an amine liquid inlet and CO 2 A steam outlet; the amine liquid outlet at the bottom of the tower is connected with the amine liquid incoming material pipeline to be purified.
The amine liquid stripper is used for desorbing CO in the lean liquid (namely the amine liquid to be purified which is fed in the system and is to be treated) which is not completely desorbed in the regeneration tower 2 Stripping out and improving CO 2 The trapping rate of the vacuum condenser is reduced. The amine liquid stripper is optional equipment and is used for removing CO in lean liquid of a system 2 The load amount determines whether to set.
The amine liquid inlet of the amine liquid stripping tower is used for conveying the amine liquid to be treated from the top to the inside of the tower, the water vapor inlet is used for inputting stripping gas low-pressure steam from the bottom of the tower, and is used for countercurrent contact with the amine liquid from the top of the tower to strip the CO in the tower 2 Stripping out, stripping out CO 2 CO from the top of the column together with rising water vapour 2 The steam outlet outputs and returns CO 2 The heat of the stream can be effectively utilized by the bottom of the regeneration tower of the trapping system or the inlet of the MVR compressor. And outputting a liquid phase at the bottom of the tower from an amine liquid outlet, mixing the liquid phase with alkali liquor, and then entering the vacuum stripping evaporation tank for subsequent treatment.
According to some preferred embodiments of the invention, the amine liquid stripper is operated at a pressure of 100 to 270kPa and at a top temperature of 80 to 110 ℃.
According to some preferred schemes of the invention, a liquid distributor connected with the amine liquid inlet and a section of random packing or structured packing positioned below the liquid distributor are arranged in the amine liquid stripping tower; the random packing material is selected from IMTP15# to 50# or other similar packing materials according to different tower diameters, the structured packing material is selected from metal plate corrugated packing materials such as M200X\M250X\M252Y and the like, and the packing height is 2-6M. The liquid distributor may specifically be a trough-type liquid distributor or the like.
According to some preferred schemes of the invention, the amine liquid stripper is provided with a reboiler, and the tower bottom is provided with an air lifting tray. The reboiler provides heat stripping or direct steam stripping. If the reboiler is arranged, the tower kettle is provided with an air lifting tray for collecting liquid phase removed from the reboiler and gas phase returned in a distributed manner, and the reboiler adopts a once-through vertical or horizontal reboiler. If stripping is direct, the tower bottom can be provided with a gas lifting tower tray for distributing steam.
In another aspect, the present invention provides a method for purifying and regenerating an amine liquid, which is performed by any one of the above amine liquid purifying and regenerating systems. The method specifically comprises the following steps:
and (3) mixing the amine liquid to be purified with alkali liquor, then entering the vacuum stripping evaporation tank, allowing the recovered gas obtained by vacuum heating evaporation to enter the vacuum condenser for condensation, allowing the condensate to enter the amine liquid tank as recovered amine liquid for storage, and allowing the non-condensable gas to be pumped out by the vacuumizing unit to maintain the vacuum degree of the system.
According to the amine liquid purification and regeneration method of the present invention, preferably, the vacuum stripping evaporation tank may be further introduced with a stripping gas selected from nitrogen, air, flue gas, steam, and CO 2 At least one of product gas, MVR flash vapor, and the like.
The main component of the noncondensable gas is N 2 、O 2 、CO 2 And water vapor, can be directly discharged.
According to the purification and regeneration method of the amine liquid, preferably, the operating pressure of the vacuum stripping evaporation tank is 2-50 kPa, the operating temperature is 100-180 ℃, and the method is specifically determined according to the composition of the amine liquid and the content of heat stable salt.
The operating pressure of the vacuum condenser is consistent with that of a vacuum stripping evaporation tank connected with the vacuum condenser, and the temperature is the dew point temperature under the corresponding operating pressure.
According to the amine liquid purification and regeneration method of the present invention, preferably, when the vacuum stripping and evaporating tank comprises a plurality of stages of vacuum stripping and evaporating tanks with pressure gradually reduced in series, the liquid phase at the tank bottom continuously enters the next stage of vacuum stripping and evaporating tank through a liquid phase pipeline. The discharge liquid in the vacuum stripping evaporation tank of the first stage is intermittently discharged through a discharge liquid outlet, and the discharge liquid in the vacuum stripping evaporation tanks of other stages is continuously discharged through the discharge liquid outlet.
According to the method for purifying and regenerating an amine liquid of the present invention, preferably, the recovered amine liquid in the amine liquid tank is pressurized to 120 to 150kPa by an amine liquid pump and is fed back to CO by filtration 2 Lean liquid tanks or underground tanks of the trapping system.
According to the amine liquid purification and regeneration method of the invention, preferably, the amine liquid to be purified firstly enters an amine liquid stripper to strip CO through low-pressure steam 2 Then mixing with alkali liquor, and entering the vacuum stripping evaporation tank for subsequent treatment.
According to the amine liquid purification and regeneration method of the present invention, preferably, the operation pressure of the amine liquid stripper is 100 to 270kPa, and the overhead temperature is 80 to 110 ℃.
The beneficial effects of the invention include:
1) The amine liquid purifying and regenerating system provided by the invention has a compact and reasonable structure, is provided with a plurality of stages of stripping evaporation, and can utilize the waste heat of the system to realize low-temperature evaporation; compared with the electrodialysis technology which consumes a large amount of electric energy, the energy-saving effect is realized; a large amount of desalted water and alkali liquor are not required to be added for regenerating resin, and a small amount of heat stable salt solution after vacuum evaporation concentration is discharged; and compared with the ion exchange resin method, the emission reduction is realized.
2) The system device of the invention has simple structure, is conventional low-cost equipment in chemical industry, has long design life, does not need to replace resin or membrane components, greatly reduces the cleaning frequency of the filter, and saves investment and maintenance cost compared with the prior art.
3) The amine liquid purifying and regenerating system provided by the invention has the advantages of simplicity, good purifying effect, convenience in operation, small occupied area and low running cost, and is suitable for popularization and use.
Drawings
FIG. 1 is a schematic diagram of an amine liquid purification system in example 1 of the present invention.
FIG. 2 is a schematic diagram of an amine liquid purification system in example 2 of the present invention.
FIG. 3 is a schematic diagram of an amine liquid purification system in example 3 of the present invention.
Reference numerals illustrate:
1. an amine liquid supply pipeline to be purified;
2. a vacuum air extracting and evaporating tank 21, a primary vacuum air extracting and evaporating tank 22 and a secondary vacuum air extracting and evaporating tank; 2-1 parts of an amine liquid inlet to be purified, 2-2 parts of a gas stripping gas inlet, 2-3 parts of a recovered gas outlet, 2-4 parts of a discharged liquid outlet, 2-5 parts of a heating coil, 2-6 parts of a nozzle type gas-liquid distributor, 2-7 parts of a baffle plate;
3. a vacuum condenser 31, a primary vacuum condenser 32 and a secondary vacuum condenser;
4. a vacuum pumping unit;
5. an amine liquid tank, 5-1, a silk screen foam remover;
6. An amine liquid pump;
7. a filtering unit;
8. an amine liquid stripping tower, 8-1, a water vapor inlet, 8-2, an amine liquid outlet, 8-3, an amine liquid inlet, 8-4 and CO 2 8-5 parts of steam outlet, 8-6 parts of liquid distributor, 8-7 parts of filler, 8-8 parts of reboiler, 8-8 parts of gas-lifting tray, 8-9 parts of tower top wire mesh demister.
Detailed Description
In order to more clearly illustrate the present invention, the present invention will be further described with reference to preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and that this invention is not limited to the details given herein.
The invention mainly provides an amine liquid purifying and regenerating system, as shown in fig. 1-3, which comprises: an amine liquid supply pipeline 1 to be purified, a vacuum stripping evaporation tank 2, a vacuum condenser 3, a vacuumizing unit 4 and an amine liquid tank 5.
The vacuum stripping evaporation tank 2 is provided with an amine liquid inlet 2-1 to be purified, a recovered gas outlet 2-3 and a discharged liquid outlet 2-4.
The amine liquid to be purified supply pipeline 1 is connected with the amine liquid inlet 2-1 to be purified and is used for inputting the amine liquid to be purified into the vacuum stripping evaporation tank 2.
An alkali liquor feed port 1-1 is arranged on the amine liquor incoming pipeline 1 to be purified and is used for mixing alkali liquor into the amine liquor to be purified; preferably, the mixed lye is adjusted to ph=9 to 10, for example NaOH solution or KOH solution. The to-be-purified amine liquid feeding pipeline 1 is preferably provided with a pressure reducing valve behind the alkali liquor feeding port, and the to-be-purified amine liquid is mixed with the alkali liquor, then subjected to pressure reduction through the pressure reducing valve and then enters the vacuum air stripping evaporation tank 2.
The recycling gas outlet 2-3 is positioned at the top of the vacuum stripping evaporation tank 2 and is connected with the amine liquid tank 5, and the vacuum condenser 3 is arranged on a connecting pipeline; the recovered gas obtained by vacuum stripping evaporation in the vacuum stripping evaporation tank 2 is condensed by the vacuum condenser 3 and then enters the amine liquid tank 5 as recovered amine liquid for storage.
The effluent outlet 2-4 is located at the bottom of the vacuum stripping evaporator 2.
The vacuumizing unit 4 is communicated with the top of the vacuum condenser 3 or the amine liquid tank 5 and is used for pumping non-condensable gas in the system and maintaining the vacuum degree required by the system. The main component of the noncondensable gas is N 2 、O 2 、CO 2 And water vapor, can be directly discharged.
The amine liquid to be purified is evaporated into active amine molecules and water vapor molecules in the vacuum stripping evaporation tank 2 through gas stripping, and then enters the vacuum condenser 3, and the condensed liquid phase is stored in the amine liquid tank 5 as recovered amine liquid. While the high boiling impurities containing the heat stable salt and the particulate matter are discharged from the bottom discharge liquid outlet of the vacuum stripping evaporation tank 2 to the waste liquid treatment device, the discharge may be continuous discharge or intermittent discharge.
With respect to the vacuum stripping and evaporating tank 2, a heating assembly, such as heating coils 2-5 or tube bundles, may optionally be provided inside to accelerate the stripping and evaporating. By adjusting the temperature in the vacuum stripping evaporation tank 2 and the gas phase partial pressure of the amine (through the heating component and the vacuumizing unit 4), the transfer of the amine molecules from the liquid phase to the gas phase is promoted, the yield of active amine is improved, the amine loss of unit product is reduced, and the three-waste emission is reduced. Preferably, the operating pressure of the vacuum stripping evaporation tank 2 is 2-50 kPa, the operating temperature is 100-180 ℃, and the operating pressure is determined according to the composition of the amine liquid and the content of the heat stable salt. Preferably, the operating pressure of the vacuum stripping evaporation tank 2 is 7.5-12 kPa, and the operating temperature is 130-180 ℃.
The vacuum stripping evaporation tank 2 can be further provided with a stripping gas inlet 2-1. The stripping gas inlet 2-1 is used for inputting stripping gas into the vacuum stripping evaporation tank 2 and stripping and evaporating amine liquid to be purified; the stripping gas is selected from nitrogen, air, flue gas, steam, CO 2 At least one of product gas, MVR flash vapor, and the like. When the vacuum air extraction effect can be satisfied only by using the heating coil pipe 2-5, the stripping air inlet 2-1 is not required.
The vacuum stripping evaporation tank 2 can be further internally provided with a nozzle type gas-liquid distributor 2-6 connected with the amine liquid inlet 2-1 to be purified, and the escape rate of active amine molecules is improved by atomizing to increase the contact specific surface area of the gas liquid. The bottom of the vacuum stripping evaporation tank 2 is preferably a conical bottom, and the discharge liquid outlets 2-4 are positioned at the conical bottom.
The vacuum stripping evaporation tank 2 can comprise a plurality of stages of vacuum stripping evaporation tanks with pressure gradually reduced in series; the vacuum stripping evaporation tanks 2 are connected through liquid phase pipelines, the recovery gas outlets 2-3 at the tops of the vacuum stripping evaporation tanks 2 at each stage are all connected with the amine liquid tank 5, and the vacuum condensers 3 are all arranged on the connecting pipelines. When the system of the invention comprises a multi-stage vacuum air extraction and evaporation tank, the liquid phase at the bottom of the tank continuously enters the next stage vacuum air extraction and evaporation tank through a liquid phase pipeline. The discharge liquid in the vacuum stripping evaporation tank of the first stage is intermittently discharged through a discharge liquid outlet, and the discharge liquid in the vacuum stripping evaporation tanks of other stages is continuously discharged through the discharge liquid outlet.
For example, as shown in fig. 1 and 3, the vacuum stripping evaporator 2 includes a primary vacuum stripping evaporator 21 and a secondary vacuum stripping evaporator 22 which are connected in series and have pressure decreasing step by step. The primary vacuum condenser 31 is arranged on a connecting pipeline between the recovery gas outlet 2-3 and the amine liquid tank 5; a secondary vacuum condenser 32 is arranged on the connecting pipeline of the recovered gas outlet 2-3 of the secondary vacuum stripping and evaporating tank 22 and the amine liquid tank 5. The primary vacuum extraction and evaporation tank 21 is also provided with an interstage amine liquid outlet which is connected with an amine liquid inlet 2-1 to be purified of the secondary vacuum extraction and evaporation tank 22; a baffle plate 2-7 can be arranged at the position of the amine liquid inlet 2-1 to be purified.
Preferably, the operating pressure of the primary vacuum stripping and evaporating tank 21 is 10-12 kPa, the operating temperature is 140-145 ℃, the operating pressure of the secondary vacuum stripping and evaporating tank 22 is 7.5-8 kPa, and the operating temperature is 130-135 ℃.
As shown in fig. 1, the vacuumizing unit 4 is respectively communicated with the primary vacuum condenser 31 and the secondary vacuum condenser 32; as shown in fig. 3, the vacuumizing unit 4 is communicated with the top of the amine liquid tank 5. The vacuum pumping unit 4 returns low-pressure steam condensate generated during the vacuum ejector to the position of the amine liquid inlet 2-1 to be purified of each stage of vacuum air extraction and evaporation tanks for recycling.
As shown in fig. 2, when the vacuumizing unit 4 is communicated with the top of the amine liquid tank 5, a wire mesh foam remover 5-1 is arranged at the lower side of a vacuumizing outlet at the top of the amine liquid tank 5; when a vacuum is drawn, gas is drawn from the top outlet and the wire mesh demister 5-1 is used to capture the amine liquid entrained by the gas. When the vacuumizing unit 4 is communicated with the vacuum condenser 3, a silk screen foam remover is arranged at a vacuumizing outlet of the vacuum condenser 3 so as to prevent gas from entraining amine liquid. Furthermore, CO at the top of the amine liquid stripper 8 2 An overhead wire mesh demister 8-9 can also be provided below the steam outlet 8-4.
With respect to the vacuum condenser 3, its operating pressure and the vacuum connected theretoThe stripping evaporator 2 is uniform and the temperature is the dew point temperature at the corresponding operating pressure. The vacuum condenser 3 can be used for pressurizing and sending the recovered gas back to CO by using a pump after liquefying the recovered gas 2 The trapping system, on the one hand, greatly reduces the load of the rear evacuation unit 4.
The vacuum condenser 3 is preferably a shell-and-tube heat exchanger, the tube side is a cooling medium, the shell side is connected with a connecting pipeline of the recovered gas outlet 2-3 and the amine liquid tank 5, and is used for condensing the recovered gas discharged from the top of the vacuum stripping evaporation tank 2, namely recovering the amine liquid, and the non-condensable gas is pumped by the vacuumizing unit 4 to maintain the vacuum degree required by the system. When the vacuum-pumping unit 4 is connected with the vacuum condenser 3, it is connected with its shell side. The cooling medium can be chilled water, circulating water or low-temperature organic refrigerant, and can be specifically selected from CO 2 The utility conditions on which the trapping device relies.
The vacuum pumping unit 4 may be a liquid ring vacuum pump or a vacuum steam ejector. Only the noncondensable gas of the system needs to be pumped out to maintain the required vacuum degree of the whole system, so that the vacuum degree can be connected with the vacuum condenser 3 or communicated with the top of the amine liquid tank 5.
Furthermore, the system of the invention is connected to an amine liquid pump 6 and a filter unit 7 after the amine liquid tank 5. The amine liquid tank 5 is used for collecting the recovered amine liquid discharged from the vacuum condenser 3, and is pressurized to 120-150 kPa by the amine liquid pump 6 to return CO 2 Lean liquid tanks or underground tanks of the trapping system. The filter unit 7 as feed CO 2 The last stage of protection measures of the trapping system. The filter unit 7 may comprise a mechanical filter and an activated carbon filter. Because particulate matter entrained in the amine liquid has been minimized by the purification of the foregoing system, the amount of impurities is greatly reduced and the maintenance cost of the filtration unit 7 is reduced as compared to prior art arrangements of the filtration device in the amine liquid purification system. The filter unit 7 preferably comprises a mechanical filter, an activated carbon filter and a three-stage filter in series with the mechanical filter.
As shown in fig. 1 and 2, in the system of the present invention, an amine liquid stripper 8 may also be provided before the vacuum stripping evaporator 2, and the amine liquid stripper 8 may be provided according to the circumstances The bottom is provided with a steam inlet 8-1 and an amine liquid outlet 8-2, and the top of the tower is provided with an amine liquid inlet 8-3 and CO 2 A steam outlet 8-4; the amine liquid outlet 8-2 at the bottom of the tower is connected with the amine liquid incoming pipeline 1 to be purified.
The amine liquid stripper 8 is used to desorb CO from the lean liquid (i.e. the amine liquid to be purified fed to the system) which is not completely desorbed in the regeneration tower 2 Stripping out and improving CO 2 The trapping rate of the vacuum condenser 3 is reduced. Amine stripper 8 is an optional device, based on the CO in the lean system solution 2 The load amount determines whether to set.
The amine liquid inlet 8-3 of the amine liquid stripping tower 8 is used for conveying the amine liquid to be treated from the top into the tower, the water vapor inlet 8-1 is used for inputting stripping gas low-pressure steam from the bottom of the tower, and is used for countercurrent contact with the amine liquid from the top of the tower to strip CO in the tower 2 Stripping out, stripping out CO 2 CO from the top of the column together with rising water vapour 2 The steam outlet 8-4 outputs and returns CO 2 The heat of the stream can be effectively utilized by the bottom of the regeneration tower of the trapping system or the inlet of the MVR compressor. The liquid phase at the bottom of the tower is output from the amine liquid outlet 8-2 and is mixed with alkali liquor and then enters the vacuum stripping evaporation tank 2 for subsequent treatment.
The operating pressure of the amine liquid stripping tower 8 is 100-270 kPa, and the tower top temperature is 80-110 ℃.
The inside of the amine liquid stripping tower 8 is provided with a liquid distributor 8-5 connected with the amine liquid inlet and a section of packing 8-6 positioned below the liquid distributor, which can be random packing or structured packing; the random packing material is selected from IMTP15# to 50# or other similar packing materials according to different tower diameters, the structured packing material is selected from metal plate corrugated packing materials such as M200X\M250X\M252Y and the like, and the height of the packing material is 2-6M. The liquid distributor 8-5 may specifically be a trough-type liquid distributor or the like.
As shown in fig. 2, the amine liquid stripper 8 may also be provided with a reboiler 8-7 at the bottom of the tower, and the tower bottom is provided with an air lift tray 8-8. The reboiler 8-7 provides heat stripping or direct steam stripping. If the reboiler is arranged, the tower kettle is provided with an air lifting tray 8-8 for collecting liquid phase removed from the reboiler 8-7 and distributing returned gas phase, and the reboiler 8-7 adopts a once-through vertical or horizontal reboiler. If stripping is direct, the column bottoms may be provided with lift trays 8-8 for distributing steam.
The amine liquid purifying and regenerating system is used for treatment, and specifically comprises the following steps:
after the amine liquid to be purified is mixed with alkali liquor, the mixture enters the vacuum stripping evaporation tank 2, the recovered gas obtained through vacuum heating evaporation enters the vacuum condenser 3 to be condensed, the condensate liquid as the recovered amine liquid enters the amine liquid tank 5 to be stored, and the non-condensable gas is pumped out by the vacuumizing unit 4 to maintain the vacuum degree of the system.
The stripping gas in the vacuum stripping and evaporating tank 2 can be selected from nitrogen, air, flue gas, steam, and CO 2 At least one of product gas, MVR flash vapor, and the like. The main component of non-condensable gas generated by condensation of the vacuum condenser 3 is N 2 、O 2 、CO 2 And water vapor, can be directly discharged. The operating pressure of the vacuum stripping evaporation tank 2 is 2-50 kPa, the operating temperature is 100-180 ℃, and the operating pressure is determined according to the composition of the amine liquid and the content of the heat stable salt. The operating pressure of the vacuum condenser 3 is consistent with that of the vacuum stripping evaporation tank 2 connected with the vacuum condenser, and the temperature is the dew point temperature under the corresponding operating pressure. When the vacuum stripping evaporation tank 2 comprises a plurality of stages of vacuum stripping evaporation tanks with pressure gradually reduced in series, the liquid phase at the tank bottom continuously enters the next stage of vacuum stripping evaporation tank through a liquid phase pipeline. The discharge liquid in the vacuum stripping evaporator 2 of the first stage is intermittently discharged through a discharge liquid outlet, and the discharge liquid in the vacuum stripping evaporators 2 of the other stages is continuously discharged through a discharge liquid outlet.
Further, the recovered amine liquid in the amine liquid tank 5 is pressurized to 120-150 kPa by an amine liquid pump 6, and is filtered and returned to CO 2 Lean liquid tanks or underground tanks of the trapping system.
According to specific conditions, CO is stripped by low-pressure steam in the amine liquid to be purified first by an amine liquid stripper 8 2 Then mixing the solution with alkali liquor, and entering the vacuum stripping evaporation tank 2 for subsequent treatment. The operating pressure of the amine liquid stripper 8 is 100 DEG to the upper270kPa, the temperature of the top of the tower is 80-110 ℃.
The following invention provides 3 specific examples for more specific illustration.
Example 1
This example uses a system as shown in fig. 1 for treating and purifying amine liquid.
The system comprises an amine liquid stripping tower 8, an amine liquid incoming pipeline 1 to be purified, a vacuum stripping evaporation tank 2 (comprising a primary vacuum stripping evaporation tank 21 and a secondary vacuum stripping evaporation tank 22 with gradually reduced pressure), a vacuum condenser 3, a vacuumizing unit 4, an amine liquid tank 5, an amine liquid pump 6 and a filtering unit 7 which are sequentially connected.
The bottom of the amine liquid stripping tower 8 is provided with a water vapor inlet 8-1 and an amine liquid outlet 8-2, and the top of the tower is provided with an amine liquid inlet 8-3 and CO 2 A steam outlet 8-4; the amine liquid outlet 8-2 at the bottom of the tower is connected with the amine liquid incoming pipeline 1 to be purified. The tower is also provided with a liquid distributor 8-5 connected with the amine liquid inlet 8-3.
The amine liquid inlet 8-3 of the amine liquid stripping tower 8 is used for conveying the amine liquid to be treated from the top into the tower, the water vapor inlet 8-1 is used for inputting stripping gas low-pressure steam from the bottom of the tower, and is used for countercurrent contact with the amine liquid from the top of the tower to strip CO in the tower 2 Stripping out, stripping out CO 2 CO from the top of the column together with rising water vapour 2 The steam outlet 8-4 outputs and returns CO 2 The heat of the stream can be effectively utilized by the bottom of the regeneration tower of the trapping system or the inlet of the MVR compressor. The liquid phase at the bottom of the tower is output from the amine liquid outlet 8-2 and is mixed with alkali liquor (NaOH or KOH solution) and then enters the primary vacuum stripping and evaporating tank 21 for subsequent treatment.
An alkali liquor feeding port 1-1 is arranged on the amine liquor incoming pipeline 1 to be purified and is used for mixing alkali liquor into the amine liquor to be purified.
The primary vacuum extraction and evaporation tank 21 and the secondary vacuum extraction and evaporation tank 22 are respectively provided with an amine liquid inlet 2-1 to be purified, a recovered gas outlet 2-3 and a discharged liquid outlet 2-4. The primary vacuum condenser 31 is arranged on a connecting pipeline between the recovery gas outlet 2-3 and the amine liquid tank 5; a secondary vacuum condenser 32 is arranged on the connecting pipeline of the recovered gas outlet 2-3 of the secondary vacuum stripping and evaporating tank 22 and the amine liquid tank 5. The primary vacuum extraction and evaporation tank 21 is also provided with an interstage amine liquid outlet which is connected with an amine liquid inlet 2-1 to be purified of the secondary vacuum extraction and evaporation tank 22; the secondary vacuum air stripping evaporation tank 22 is also provided with a stripping air inlet 2-2, and a baffle plate 2-7 is also arranged at the position of the amine liquid inlet 2-1 to be purified.
The vacuumizing unit 4 is respectively communicated with the primary vacuum condenser 31 and the secondary vacuum condenser 32. The operating pressure of the vacuum condenser is consistent with that of a vacuum stripping evaporation tank connected with the vacuum condenser, and the temperature is the dew point temperature under the corresponding operating pressure. The vacuum condenser 3 is a shell-and-tube heat exchanger, the tube side is a cooling medium, and the shell side is connected with a connecting pipeline of the recovered gas outlet 2-3 and the amine liquid tank 5 and is used for condensing the recovered gas discharged from the top of the vacuum stripping evaporation tank 2, and the condensate, namely the recovered amine liquid, is pumped by the vacuumizing unit 4 to maintain the required vacuum degree of the system. The vacuum-pumping unit 4 is connected to the shell side of the vacuum condenser 3.
The specific processing process and parameters comprise:
flue gas CO from ethylene cracking furnace 2 Lean amine liquid of the trap regeneration tower enters from the top of the amine liquid stripping tower 8 at a flow rate of 5000kg/h, the operation pressure of the stripping tower is 120kPa, and the temperature of the top of the stripping tower is 109 ℃.
Organic amine MDEA in lean amine solution: 35wt%, MEA:5wt%, CO 2 Content 2wt%, heat stable salt (SO 4) 2- 、COOH - 、NO 3 - Etc.) is 3wt%.
Low-pressure steam at 150 ℃ enters the bottom of an amine liquid stripping tower at the flow rate of 300kg/h, the amine liquid from top to bottom is heated and stripped, and CO in the stripped amine liquid 2 The content is reduced to below 0.01wt percent, and is led out from the bottom of the amine liquid stripping tower 8 at the flow rate of 4980kg/h, 30 percent NaOH solution is added, the pH is regulated to about 9.8, and the solution enters a primary vacuum air stripping evaporation tank 21.
The primary vacuum stripping and evaporating tank 21 has an operating pressure of 10kPa, an operating temperature of 140 ℃, heating coils 2-5 are arranged in the tank, and a heating medium in the coils is low-pressure steam at 150 ℃. The operating pressure of the secondary vacuum stripping and evaporating tank 22 is 8kPa, the operating temperature is 135 ℃, the stripping gas is raw material smoke and low-pressure steam at 110 ℃, and a heating coil is not arranged in the tank.
The primary vacuum condenser 31 and the secondary vacuum condenser 32 each use circulating water as a cooling medium.
The filtering unit 7 adopts a three-stage filter mode of series connection of a mechanical filter, an activated carbon filter and a mechanical filter, and the filtering precision is 1 mu m.
The evacuation unit 4 employs a vacuum ejector. The steam condensate generated by the vacuum ejector is converged into each stage of vacuum air extraction and evaporation tanks.
The main performance indexes of the amine liquid purification system in this example are compared with those of the conventional electrodialysis technology and ion exchange resin technology as shown in table 1 below:
TABLE 1
Recovery rate of amine liquid Waste water amount (kg/h) Investment (Wanyuan) Heat stable salt removal rate
This embodiment 99.60％ ～260 ～100 >95％
Ion exchange resin technology 99.50％ ～6200 ～320 70～80％
Electrodialysis technology 98％ ～1900 ～700 <70％
As can be seen by comparing the table 1, compared with the prior art, the amine liquid purifying and regenerating device provided by the invention has the advantages that the wastewater discharge amount is greatly reduced, the amine liquid recovery rate is improved, and the investment is obviously reduced.
Example 2
As shown in fig. 2, compared with the embodiment 1, the system comprises a vacuum extracting and evaporating tank 2 and a vacuum condenser 3, wherein a vacuumizing unit 4 is directly connected to the top of an amine liquid tank 5, and noncondensable gas condensed by the vacuum condenser 3 is extracted from the system. The lower side of the top vacuumizing outlet of the amine liquid tank 5 is provided with a silk screen foam remover 5-1; when a vacuum is drawn, gas is drawn from the top outlet and the wire mesh demister 5-1 is used to capture the amine liquid entrained by the gas.
The amine liquid stripping tower 8 is also provided with a reboiler 8-7 at the bottom of the tower, and the tower bottom is provided with an air lifting tower tray 8-8. Reboiler 8-7 was directly vented to steam stripping. The lift trays 8-8 are used to collect the liquid phase from the reboiler 8-7 and the gas phase returned from the distribution, and the reboiler 8-7 is a once-through vertical or horizontal reboiler. In addition, the amine liquid stripper 8 is at the top of the column at CO 2 An overhead wire mesh demister 8-9 is also arranged below the steam outlet 8-4.
The specific processing process and parameters comprise:
CO from the tail gas of a miltzkiln in a steel mill 2 Lean trap regeneration towerThe amine liquid was fed from the top of the amine liquid stripper 8 at a flow rate of 1500kg/h, the stripper operating pressure 284kPa, the top temperature 135 ℃.
Organic amine MDEA in lean amine liquid: 49wt%, CO 2 Content 1.7wt%, heat stable salt (SO 4) 2- 、COOH - 、NO 3 - Etc.) is 3wt%.
Low-pressure steam at 175 ℃ enters a reboiler 8-7 at the bottom of an amine liquid stripping tower 8 at a flow rate of 597kg/h, the amine liquid from top to bottom is heated and stripped, and CO in the stripped amine liquid 2 The content is reduced to below 0.2wt percent, 1002kg/h of flow is led out from the bottom of the amine liquid stripping tower 8, 30 percent NaOH solution is added, the pH is regulated to about 9.1, and the mixture enters the vacuum air stripping evaporation tank 2.
The operating pressure of the vacuum stripping and evaporating tank 2 is 7.5kPa, the operating temperature is 176 ℃, the stripping gas is 175 ℃ low-pressure steam, a heating tube bundle is arranged in the tank, and the heating medium in the tube bundle is 175 ℃ low-pressure steam.
The vacuum condenser 3 uses circulating water as a cooling medium.
The filtering unit 7 adopts a three-stage filtering mode of series connection of a mechanical filter, an activated carbon filter and a mechanical filter, and the filtering precision is 1 mu m.
The vacuum pumping system adopts a liquid ring type vacuum pump.
The main performance indexes of the amine liquid purification apparatus in this example are compared with those of the conventional electrodialysis technology and ion exchange resin technology as shown in table 2 below:
TABLE 2
Recovery rate of amine liquid Waste water amount (kgh) Investment (Wanyuan) Heat stable salt removal rate
This embodiment 99.60％ ～33 ～55 >95％
Ion exchange resin technology 99％ ～1600 ～220 70～80％
Electrodialysis technology 97％ ～500 ～420 <70％
CO from the amine liquid stripped from the amine liquid stripper in example 2 2 The content (less than 0.2 wt%) is higher than that of example 1 (less than 0.01 wt%), so that the recovery of amine solution obtained by both ion exchange resin and electrodialysis techniques is lower than that of example 1. Compared with the prior art, the amine liquid purification and regeneration system provided by the invention has the advantages that the discharge amount of wastewater is greatly reduced, the recovery rate of the amine liquid is improved, and the investment is obviously reduced.
Example 3
As shown in fig. 3, the system is not provided with an amine liquid stripper 8 in comparison with example 1. The vacuumizing unit is connected to the top of the amine liquid tank 5 and has only one vacuumizing point.
The specific processing process and parameters comprise:
CO from a coal-fired power plant 2 Leading out lean amine liquid in a regeneration tower of the trapping device from a lean liquid pump at a flow rate of 3000kg/h, wherein organic amine MDEA in the lean amine liquid: 48wt%, CO 2 Content 1.5wt%, heat stable salt (SO 4 2- 、COOH - 、NO 3 - Etc.) is 2 wt.%, the lean amine solution temperature is 102 deg.c, the pressure is 0.5MPa. A 30% NaOH solution was injected into the lean amine solution line, the pH was adjusted to about 9.6, and the solution was fed into the first vacuum stripping evaporator 21.
The primary vacuum stripping and evaporating tank 21 has an operating pressure of 12kPa, an operating temperature of 142 ℃, a heating coil is arranged in the tank, and a heating medium in the coil is low-pressure steam at 150 ℃. The operating pressure of the secondary vacuum stripping evaporation tank is 7.5kPa, the operating temperature is 134 ℃, the stripping gas is 150 ℃ low-pressure steam, and a heating coil is not arranged in the tank.
The primary vacuum condenser 31 and the secondary vacuum condenser 32 each use circulating water as a cooling medium.
The filtering unit 7 adopts a three-stage filtering mode of series connection of a mechanical filter, an activated carbon filter and a mechanical filter, and the filtering precision is 1 mu m.
The vacuum pumping system adopts a vacuum ejector. The vapor condensate from the vacuum ejector is directed to a secondary vacuum stripping evaporator 22.
The main performance indexes of the amine liquid purification apparatus in this example are compared with those of the conventional electrodialysis technology and ion exchange resin technology as shown in table 3 below:
TABLE 3 Table 3
Recovery rate of amine liquid Waste water amount (kg/h) Investment (Wanyuan) Heat stable salt removal rate
This embodiment 99.50％ ～60 ～80 >95％
Ion exchange resin technology 98％ ～6400 ～420 60～75％
Electrodialysis technology 96％ ～2000 ～680 <70％
In example 1 and example 2 each provided with a stripping column, the stripping column stripped amine liquid in example 2 was CO 2 The content (less than 0.2 wt%) was higher than that of example 1 (less than 0.01 wt%), thus an attempt was made to compare the lean amine solution with CO without the stripper set up in example 3 2 The content (1.5 wt%) is higher than that of examples 1 and 2, so that the recovery rate of amine liquid obtained by the ion exchange resin and electrodialysis technique is lower than that of example 1, the scale of the ion exchange resin and electrodialysis membrane is increased, and more than half of the capacity is wasted in removing CO from lean amine liquid 3 2- And HCO 3 - The service life of the amine liquid regeneration device is shortened, and more wastewater is generated. Compared with the prior art, the amine liquid purifying and regenerating system provided by the invention can be seenGreatly reduces the discharge amount of technical wastewater, improves the recovery rate of amine liquid, obviously reduces investment, and CO in lean liquid 2 Still can achieve very high amine recovery rate under the condition of high content, and has higher adaptability and flexibility.
It should be understood that the foregoing examples of the present invention are provided merely for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention, and that various other changes and modifications may be made therein by one skilled in the art without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (21)

1. An amine liquid purification and regeneration system, wherein the amine liquid purification and regeneration system comprises: an amine liquid supply pipeline to be purified, a vacuum stripping evaporation tank, a vacuum condenser, a vacuumizing unit and an amine liquid tank;
the vacuum stripping evaporation tank is provided with an amine liquid inlet to be purified, a recovered gas outlet and a discharged liquid outlet;
The to-be-purified amine liquid incoming pipeline is connected with the to-be-purified amine liquid inlet; an alkali liquor feeding port is arranged on the amine liquid incoming pipeline to be purified;
the recycling gas outlet is positioned at the top of the vacuum stripping evaporation tank and is connected with the amine liquid tank, and the vacuum condenser is arranged on the connecting pipeline;
the discharge liquid outlet is positioned at the bottom of the vacuum stripping evaporation tank;
the vacuumizing unit is communicated with the top of the vacuum condenser or the top of the amine liquid tank.
2. The amine liquid purification regeneration system of claim 1, wherein a heating assembly is disposed inside the vacuum stripping evaporator.
3. The amine liquid purification and regeneration system as claimed in claim 2, wherein the operating pressure of the vacuum stripping evaporation tank is 2 to 50kPa absolute and the operating temperature is 100 to 180 ℃.
4. The amine liquid purification regeneration system of claim 1, wherein the vacuum stripping evaporator is provided with a stripping gas inlet.
5. The amine liquid purification and regeneration system as claimed in claim 1, wherein the vacuum stripping evaporation tank is further provided with a nozzle type gas-liquid distributor connected with the amine liquid inlet to be purified.
6. The amine liquid purification and regeneration system as claimed in claim 1, wherein the vacuum condenser is a shell-and-tube heat exchanger, a tube side is a cooling medium, and a shell side is connected with a connecting pipeline of the recovered gas outlet and an amine liquid tank;
When the vacuumizing unit is connected with the vacuum condenser, the vacuumizing unit is connected with a shell side of the vacuum condenser.
7. The amine liquid purification and regeneration system as recited in claim 1 wherein said vacuum stripping and evaporating tank comprises a plurality of stages of vacuum stripping and evaporating tanks connected in series with a pressure step-down; the multistage vacuum stripping evaporation tanks are connected through liquid phase pipelines, recovery gas outlets at the tops of the vacuum stripping evaporation tanks at each stage are all connected with the amine liquid tanks, and the vacuum condensers are all arranged on the connecting pipelines.
8. The amine liquid purification and regeneration system as recited in claim 7 wherein said vacuum stripping and evaporating tank comprises a primary vacuum stripping and evaporating tank and a secondary vacuum stripping and evaporating tank connected in series with a gradual decrease in pressure;
an amine liquid inlet to be purified of the primary vacuum air extraction and evaporation tank is connected with an amine liquid incoming pipeline to be purified, and a primary vacuum condenser is arranged on a connecting pipeline of a recovered gas outlet and the amine liquid tank;
the primary vacuum extraction and evaporation tank is also provided with an interstage amine liquid outlet which is connected with an amine liquid inlet to be purified of the secondary vacuum extraction and evaporation tank;
and a secondary vacuum condenser is arranged on a connecting pipeline between the recovered gas outlet of the secondary vacuum extraction and evaporation tank and the amine liquid tank.
9. The amine liquid purification and regeneration system as recited in claim 8 wherein said evacuation unit is in communication with said primary and secondary vacuum condensers, respectively; or the vacuumizing unit is communicated with the top of the amine liquid tank.
10. The amine liquid purification and regeneration system of claim 1, wherein the vacuum unit is a liquid ring vacuum pump or a vacuum steam ejector.
11. The amine liquid purification and regeneration system of claim 1, wherein an amine liquid pump is connected after the amine liquid tank.
12. The amine liquid purification regeneration system of claim 11, wherein the amine liquid pump is followed by a filtration unit.
13. The amine liquid purification and regeneration system as claimed in claim 12, wherein the amine liquid incoming line to be purified is provided with a pressure reducing valve after the lye feed inlet.
14. The amine liquid purification and regeneration system as recited in any one of claims 1 to 13, wherein the amine liquid purification and regeneration system is further provided with an amine liquid stripper column prior to the vacuum stripping evaporator;
the bottom of the amine liquid stripping tower is provided with a water vapor inlet and an amine liquid outlet, and the top of the tower is provided with an amine liquid inlet and CO 2 A steam outlet; the amine liquid outlet at the bottom of the tower is connected with the amine liquid incoming material pipeline to be purified.
15. The amine liquid purification and regeneration system as recited in claim 14 wherein said amine liquid stripper operates at a pressure of 100 to 270kPa and a top temperature of 80 to 110 ℃.
16. The amine liquid purification and regeneration system as recited in claim 14 wherein a liquid distributor connected to said amine liquid inlet and a section of random or structured packing located below said liquid distributor are disposed within said amine liquid stripper.
17. The amine liquid purification and regeneration system as recited in claim 14 wherein said amine liquid stripper is provided with a reboiler and the bottoms are provided with an air lift tray.
18. An amine liquid purification and regeneration method, which is carried out by the amine liquid purification and regeneration system as claimed in any one of claims 1 to 17, and specifically comprises the following processes:
and (3) mixing the amine liquid to be purified with alkali liquor, then entering the vacuum stripping evaporation tank, allowing the recovered gas obtained by vacuum heating evaporation to enter the vacuum condenser for condensation, allowing the condensate to enter the amine liquid tank as recovered amine liquid for storage, and allowing the non-condensable gas to be pumped out by the vacuumizing unit to maintain the vacuum degree of the system.
19. The amine liquid purification and regeneration method as claimed in claim 18, wherein the vacuum stripping evaporation tank is further filled with a stripping gas selected from nitrogen, air, flue gas, steam, and CO 2 At least one of product gas and MVR flash gas.
20. The amine liquid purification and regeneration method as claimed in claim 18, wherein the recovered amine liquid in the amine liquid tank is pressurized to 120 to 150kPa by an amine liquid pump and is fed back to CO by filtration 2 Lean liquid tanks or underground tanks of the trapping system.
21. The amine liquid purification and regeneration method as claimed in claim 18, wherein the amine liquid to be purified is firstly fed into an amine liquid stripper to strip CO through low-pressure steam 2 Then mixing with alkali liquor, and entering the vacuum stripping evaporation tank for subsequent treatment.
CN202310981153.8A 2023-08-04 2023-08-04 Amine liquid purification and regeneration system and method Pending CN116870663A (en)

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