System and method for removing heat-stable salt from organic amine solution

Abstract

The present invention relates to the field of organic amine liquid purification, and discloses a system for removing heat-stable salts in organic amine liquid and a method for treating organic amine liquid using the system. The system comprises: an organic amine liquid storage device, an electrode liquid storage device, a desalted water storage device and a membrane stack, wherein the membrane stack is respectively connected with the organic amine liquid storage device, the electrode liquid storage device and the desalted water storage device, and forms an organic amine liquid circulation loop, an electrode liquid circulation loop and a desalted water circulation loop respectively, and the system also comprises a conductivity meter and a control center, wherein the control center is used to receive a conductivity signal from the conductivity meter, and adjust the circulation flow of the organic amine liquid circulation loop and the desalted water circulation loop, and the reuse and discharge of the organic amine liquid and waste liquid according to the conductivity signal of the conductivity meter. When treating the organic amine liquid, the system can remove anions and cations in the amine liquid synchronously, and reduce the consumption of alkali liquid and the discharge of waste liquid.

Description

Technical Field

[0001] The invention relates to the field of organic amine liquid purification, and in particular to a system for removing heat-stable salts from organic amine liquid and a method for treating organic amine liquid containing heat-stable salts by using the system. Background Art

[0002] In the field of petrochemicals, many raw gases contain a large amount of acidic gases, such as carbon dioxide (CO2), hydrogen sulfide (H2S), sulfur dioxide (SO2), etc. These acidic gases need to be removed before entering the next process flow.

[0003] The organic amine method is widely used to remove acid gases from natural gas, liquefied gas and flue gas. Among them, commonly used organic amines include ethanolamine (MEA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), triethanolamine, N-methylethylenediamine, diisopropanolamine, N,N-dibutylethanolamine, ethylenediamine, diethylamine, tetramethylethylenediamine, piperazine, etc. However, in the process of cyclic removal of acid gases, the degradation and oxidation of organic amines during high-temperature regeneration, inorganic salts carried in the gas, and strong acidic substances in the gas will lead to an increase in the content of heat-stable salts in organic amines. The increase in heat-stable salts will cause problems such as foaming of organic amine liquid and corrosion of pipelines, and further promote the degradation and deterioration of amine liquid, forming a vicious cycle, thereby causing the ability of amine liquid to remove acid gases to decrease or even become unusable. Every year, a large amount of waste amine liquid needs to be treated, which not only has huge treatment costs, but also causes waste of resources.

[0004] In order to solve the above problems, the prior art generally involves filtering the desulfurization amine solution and then purifying it using an ion exchange method.

[0005] For example, CN102125803A discloses a method for purifying inferior amine liquid, which comprises the following steps: (1) filtering solid impurities: filtering solid impurities in the inferior amine liquid by filtering a filter medium in a fixed bed, wherein the filter medium is one or more of a molecular sieve, activated carbon and an ion exchange membrane; (2) removing acid radical ions by exchange: loading a mixed resin into an ion exchange column, passing the filtered amine liquid through a mixed ion exchange resin at an air velocity of 1-50 h -1 , the acid radical ions are exchanged and removed at a temperature of 10-50°C; (3) Regeneration of the filter medium and exchange resin: When the pressure drop of the amine solution passing through the filter medium is too high and the air velocity is too low, the filter medium is regenerated or replaced to facilitate smooth filtration of the amine solution and reduce the filtration time; when the pH values ​​of the inlet and outlet amine solutions of the ion exchange resin tower are close, the ion exchange resin is regenerated, and the air velocity for regenerating the ion exchange resin is 1-50h -1 , the temperature is 10-50℃; the regenerated resin is recycled.

[0006] However, the above method can only remove solid particles and heat-stable salt anions from the amine solution, but cannot remove cations (such as Na + , K + , Ca 2+ Mg 2+ In addition, the ion exchange method consumes a large amount of alkaline solution (such as NaOH) and discharges a large amount of strongly alkaline wastewater. In the process of circulating desalination, the discharge of wastewater even reaches 1-2 times the amount of amine solution in the system. The COD of the wastewater is very high and it is currently impossible to effectively treat it. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the existing ion exchange technology for removing heat-stable salts from amine liquid, such as large consumption of chemical agents, large amount of waste liquid discharge and difficulty in removing cations, and to provide a system for removing heat-stable salts from organic amine liquid and a method for treating organic amine liquid containing heat-stable salts using the system. The system has strong desalination capacity, is suitable for treating a variety of organic amine liquids containing different types of heat-stable salts, is easy to assemble, highly automated, and saves labor costs. The use of the system to treat organic amine liquid containing heat-stable salts can not only achieve the simultaneous removal of anions and cations in the amine liquid and a high removal depth, but also greatly reduce or eliminate the consumption of alkali liquid, reduce the amount of waste liquid discharge, and enhance the repeatable service life of the organic amine liquid.

[0008] In order to achieve the above-mentioned purpose, the present invention provides a system for removing heat-stable salts from an organic amine solution, the system comprising: an organic amine solution storage device, an electrode solution storage device, a desalted water storage device, a membrane stack and a control center, wherein the membrane stack is connected to the organic amine solution storage device, the electrode solution storage device and the desalted water storage device respectively; the membrane stack is provided with at least one organic amine solution inlet, an organic amine solution outlet, a waste liquid inlet, a waste liquid outlet, an electrode solution inlet and an electrode solution outlet; the organic amine solution outlet and the waste liquid outlet are respectively provided with a first conductivity meter and a second A conductivity meter is used to monitor the liquid conductivity at the organic amine liquid outlet and the waste liquid outlet; a first regulating valve is provided on the material conveying pipeline between the organic amine liquid outlet and the organic amine liquid storage device, and a second regulating valve is provided on the material conveying pipeline between the desalted water storage device and the waste liquid inlet; the system also includes a control center for receiving conductivity signals from the first conductivity meter and the second conductivity meter, and adjusting the opening of the first regulating valve and the second regulating valve according to the conductivity signals of the first conductivity meter and the second conductivity meter.

[0009] The second aspect of the present invention provides a method for treating an organic amine liquid containing heat-stable salts by using the aforementioned system for removing heat-stable salts from an organic amine liquid, the method comprising introducing the organic amine liquid to be treated into the organic amine liquid storage device of the system through an external pipeline, introducing deionized water into the deionized water storage device of the system, introducing electrode liquid into the electrode liquid storage device, and then circulating the organic amine liquid into the amine liquid chamber of the membrane stack, circulating the deionized water in the deionized water storage device into the waste liquid chamber of the membrane stack, and circulating the electrode liquid in the electrode liquid storage device into the waste liquid chamber of the membrane stack. The anode chamber and cathode chamber of the membrane stack; the anode plate and cathode plate of the membrane stack are connected to the positive and negative electrodes of the power supply respectively, so that the organic amine liquid to be treated which is circulated and pumped into the membrane stack is treated to remove heat-stable salts, so as to obtain an organic amine liquid removed from heat-stable salts and desalted water enriched in heat-stable salts. When the obtained organic amine liquid removed from heat-stable salts and the desalted water enriched in heat-stable salts meet the recovery and discharge standards respectively, the organic amine liquid removed from heat-stable salts obtained after treatment is transported to the organic amine liquid reuse system, and the desalted water enriched in heat-stable salts obtained after treatment is discharged as waste liquid outside the system.

[0010] The existing methods for removing heat-stable salts from amine solutions rarely involve the removal of cations. However, when cations accumulate to a certain extent in organic amines (such as more than 1000ppm), the desulfurization efficiency of the desulfurized organic amine solution will be greatly affected. For example, when an amine solution containing a large amount of sodium ions is used to remove hydrogen sulfide in liquefied gas, the hydrogen sulfide content in the lean amine solution will increase, the desulfurization depth of the liquefied gas will decrease, and even the sulfur content of the liquefied gas after desulfurization will exceed the standard, and its harmfulness will even exceed the heat-stable salt anion. According to conventional theory, the amine solution itself should be easy to react with the cation exchange resin in the aqueous solution. Therefore, if the cation exchange resin is used to remove the cations, a competitive exchange relationship will be formed in the process of removing the cations, resulting in a large amount of loss of the amine solution itself, which is not conducive to industrial production. Therefore, how to effectively remove the cations in the amine solution has always been a technical problem in this field. In order to avoid the influence caused by the excessive cation content, the commonly used method is to replace fresh organic amines and discharge the severely degraded organic amines, but this will lead to the increase of operating costs, environmental pollution and waste of resources.

[0011] After in-depth research, the inventors of the present invention found that under the action of electrodialysis, organic amines containing heat-stable salts can cause charged particles in the heat-stable salts to migrate in a directional manner and enter different compartments, and continuously separate, concentrate and remove, thereby achieving purification of the organic amine solution. However, as the purification process proceeds, the concentration of the heat-stable salts in the organic amine solution continues to decrease, and the conductivity of the organic amine solution will gradually decrease. In theory, when the concentration of the heat-stable salts decreases to 0 or close to 0, there are almost no mobile charged particles in the organic amine solution, resulting in low conductivity of the organic amine solution. The decrease in the conductivity of the organic amine solution in the amine solution chamber during the electrodialysis process can lead to serious consequences, such as: (1) the organic amine solution is ionized and enters the desalted water compartment, resulting in the loss of the organic amine solution, and further desalination cannot be completed; (2) it will cause the current efficiency to decrease, and the electrical energy will be further converted into thermal energy, resulting in an increase in the temperature of the organic amine solution, causing irreversible damage to the ion exchange membrane. In order to solve this problem, the inventor of the present invention found that when the amine liquid compartment of the electrodialysis is filled with ion exchange resin, when the electrical conductivity of the organic amine liquid decreases or even cannot conduct electricity, the ion exchange resin acts as a conductive medium, which can effectively promote the electrodialysis process and improve the electrodialysis desalination efficiency. In addition, a control center is set in the system, and the full automation of the heat-stable salt removal process in the organic amine liquid can be realized. When the organic amine liquid to be removed from the heat-stable salt and the desalted water enriched with the heat-stable salt meet the recovery and discharge standards respectively, the purified organic amine liquid can be automatically recovered and / or the waste liquid is discharged. After the organic amine liquid is recovered and / or the waste liquid is discharged, the system automatically replenishes the organic amine liquid and / or the desalted water, and no manual intervention is required throughout the process, which greatly saves labor costs. Therefore, the system provided by the present invention has a high depth of removal of heat-stable salts in the organic amine liquid, a high degree of automation, effectively reduces operating costs, and improves the desulfurization efficiency of the organic amine liquid.

[0012] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic flow diagram of treating an organic amine solution containing heat-stable salts by using the system for removing heat-stable salts from an organic amine solution provided by the present invention when the membrane stack is a cation-cation membrane stack;

[0014] Figure 2 It is a schematic diagram of the structure and working principle of the membrane stack of the present invention which is a bipolar membrane stack.

[0015] Description of Reference Numerals

[0016] 1. Organic amine liquid storage device 2. Electrode liquid storage device 3. Desalted water storage device

[0017] 4. Membrane stack 5. Control center 61. First regulating valve

[0018] 62, second regulating valve 63, third regulating valve 64, fourth regulating valve

[0019] 65, fifth regulating valve 66, sixth regulating valve 67, seventh regulating valve

[0020] 71. Organic amine liquid circulation pump 72. Electrode liquid circulation pump 73. Demineralized water circulation pump

[0021] 81. Organic amine liquid level meter 82. Desalted water level meter 91. First conductivity meter

[0022] 92. Second conductivity meter A, first ion exchange membrane B, second ion exchange membrane

[0023] C. Third ion exchange membrane I-1, anode chamber I-2, cathode chamber

[0024] II. Amine liquid room III. Waste liquid room DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0026] The first aspect of the present invention provides a system for removing heat-stable salts from an organic amine solution, such as Figure 1 As shown, the system includes: an organic amine liquid storage device 1, an electrode liquid storage device 2, a desalted water storage device 3, a membrane stack 4 and a control center 5, wherein the membrane stack 4 is connected to the organic amine liquid storage device 1, the electrode liquid storage device 2 and the desalted water storage device 3 respectively; the membrane stack 4 is provided with at least one organic amine liquid inlet, an organic amine liquid outlet, a waste liquid inlet, a waste liquid outlet, an electrode liquid inlet and an electrode liquid outlet; the organic amine liquid outlet and the waste liquid outlet are respectively provided with a first conductivity meter 91 and a second conductivity meter 92 for monitoring the conductivity of the organic amine liquid outlet and the waste liquid outlet. Liquid conductivity at the waste liquid outlet; a first regulating valve 61 is arranged on the material conveying pipeline between the organic amine liquid outlet and the organic amine liquid storage device 1, and a second regulating valve 62 is arranged on the material conveying pipeline between the desalted water storage device 3 and the waste liquid inlet; the system also includes a control center 5 for receiving conductivity signals from the first conductivity meter 91 and / or the second conductivity meter 92, and adjusting the opening of the first regulating valve 61 and / or the second regulating valve 62 according to the conductivity signals of the first conductivity meter 91 and / or the second conductivity meter 92.

[0027] According to the present invention, the control center 5 is preferably an automatic control device and human-computer interface interaction is realized by programmable software. The control center 5 can automatically adjust the opening of the first regulating valve 61 and / or the second regulating valve 62 according to the changes in the conductivity signal of the first conductivity meter 91 and / or the second conductivity meter 92, thereby automatically monitoring and controlling the flow rate and circulation and discharge frequency of the organic amine liquid and / or desalted water to be treated.

[0028] According to the present invention, preferably, the control center 5 can set the conductivity signal difference or conductivity signal value of the organic amine liquid according to actual conditions. When the conductivity signal difference or conductivity signal value measured by the first conductivity meter 91 reaches the set conductivity signal difference or the set conductivity signal value, it indicates that the organic amine liquid to be treated has reached the desalination standard, and the third regulating valve 63 arranged on the output pipeline of the organic amine liquid is opened to output the treated organic amine liquid that meets the standard to the organic amine liquid reuse system.

[0029] According to the present invention, Figure 1 As shown, the membrane stack 4 includes an anode plate and a cathode plate relatively arranged at both ends of the membrane stack 4, and a module containing multiple ion exchange membranes arranged between the anode plate and the cathode plate; the area between the anode plate and the module forms an anode chamber I-1, and the area between the cathode plate and the module forms a cathode chamber I-2; the multiple ion exchange membranes separate multiple periodically alternately arranged amine liquid chambers II and waste liquid chambers III in the module; the ion selective permeability of two adjacent ion exchange membranes is different; the organic amine liquid inlet and the organic amine liquid outlet are arranged on the opposite sides of each of the amine liquid chambers II, the waste liquid inlet and the waste liquid outlet are arranged on the opposite sides of each of the waste liquid chambers III, and the electrode liquid outlet and the electrode liquid outlet are respectively arranged on the opposite sides of the anode chamber I-1 and the cathode chamber I-2;

[0030] The liquid outlet of the organic amine liquid storage device 1 is connected to the organic amine liquid inlet of the amine liquid chamber II of the membrane stack 4, and the liquid inlet of the organic amine liquid storage device 1 is connected to the organic amine liquid outlet of the amine liquid chamber II of the membrane stack 4, forming a closed loop, which becomes an organic amine liquid circulation loop;

[0031] The electrode liquid outlet of the electrode liquid storage device 2 is connected to the electrode liquid inlet of the anode chamber I-1 and the cathode chamber I-2, and the electrode liquid inlet of the electrode liquid storage device 2 is connected to the electrode liquid outlet of the anode chamber I-1 and the cathode chamber I-2, forming a closed loop, which becomes an electrode liquid circulation loop;

[0032] The desalted water outlet of the desalted water storage device 3 is connected to the waste liquid inlet of the waste liquid chamber III, and the desalted water inlet of the desalted water storage device 3 is connected to the waste liquid outlet of the waste liquid chamber III to form a closed loop, which becomes a desalted water circulation loop.

[0033] According to the present invention, in order to enable the membrane stack 4 to continue the electrodialysis process when the conductivity of the organic amine liquid decreases or even fails to conduct electricity, and to improve the desalination efficiency of the membrane stack 4 for the heat-stable salt in the organic amine liquid, preferably, ion exchange resin can also be filled between the two ion exchange membranes of each amine liquid chamber II separated in the membrane stack 4; the ion exchange resin can be a strongly acidic cation exchange resin and / or a strongly basic anion exchange resin.

[0034] According to the present invention, the strong acid cation exchange resin can be a macroporous strong acid cation exchange resin and / or a gel-type strong acid cation exchange resin, and the cations in the strong acid cation exchange resin can be any cations, such as organic cations (such as quaternary ammonium cations), alkali metal ions (Na + , K + ), alkaline earth metal ions (such as Mg 2+ , Ca 2+ ), transition metal ions (such as Cu 2+ , Fe 3+ Cr 3+ 、Zn 2+ 、Co 2+ 、Ni 2+ wait).

[0035] According to the present invention, the strong basic anion exchange resin can be a macroporous strong basic anion exchange resin and / or a gel-type strong basic anion exchange resin, and the anions in the strong basic anion exchange resin can be any anion, such as SO4 2- 、NO3 - , Cl - 、HCO3 - OH - wait.

[0036] According to the present invention, when the organic amine liquid treated by the system for removing heat-stable salts in the organic amine liquid contains no metal cations, the ion exchange resin is preferably a strong basic anion exchange resin, more preferably a hydroxide-type strong basic anion exchange resin, because the organic amine liquid is an alkaline solution, and the most suitable for stably exerting ion conductivity in the alkaline solution is the hydroxide-type strong basic anion exchange resin; when the organic amine liquid treated by the system for removing heat-stable salts in the organic amine liquid contains metal cations, the ion exchange resin is preferably a mixture of a strong basic anion exchange resin and a strong acid cation exchange resin, more preferably a mixture of a hydroxide-type strong basic anion exchange resin and a sodium-type strong acid cation exchange resin, and the volume ratio of the strong basic anion exchange resin to the strong acid cation exchange resin can be 0.5-2:1.

[0037] According to the present invention, the amount of the ion exchange resin is not particularly limited, as long as it can play a conductive role when the conductivity of the organic amine liquid decreases or even fails to conduct electricity. Preferably, the amount of the ion exchange resin is sufficient to fill each of the amine liquid chambers II.

[0038] According to the present invention, the electrode liquid is an electrolyte solution, the concentration of the electrolyte solution can be 3-10% by weight, preferably 4-6% by weight, the solute of the electrolyte solution can be but not limited to one or more of sodium sulfate, sodium chloride, sodium nitrate, sodium acetate, potassium chloride, sodium hydroxide, sulfuric acid, hydrochloric acid, and nitric acid, and its main purpose is to conduct electricity, ensure sufficient ions in and out, and improve current efficiency.

[0039] According to the present invention, the membrane stack 4 can be a cationic membrane stack or a bipolar membrane stack, and the two adjacent ion exchange membranes with different selective permeabilities in the membrane stack 4 include a first ion exchange membrane A and a second ion exchange membrane B. When the membrane stack 4 is a cationic membrane stack, the first ion exchange membrane A and the second ion exchange membrane B are respectively an anion exchange membrane or a cation exchange membrane; when the membrane stack 4 is a bipolar membrane stack, the first ion exchange membrane A and the second ion exchange membrane B are respectively an anion exchange membrane or a bipolar membrane.

[0040] According to the present invention, when the membrane stack 4 is a cation membrane stack, the membrane stack 4 may include multiple groups of ion exchange membranes, each group of ion exchange membranes includes a cation exchange membrane and an anion exchange membrane, forming a repeating unit, and the repeating unit formed by the multiple groups of ion exchange membranes separates multiple periodically alternately arranged amine liquid chambers II and waste liquid chambers III. The arrangement of the ion exchange membranes with different ion selective permeabilities in the membrane stack 4 can be the arrangement of the conventional cation membrane stacks in the art, for example, the arrangement of the ion exchange membranes in the membrane stack 4 can be as follows Figure 1As shown, in the membrane stack 4, the first ion exchange membrane A is a cation exchange membrane, and the second ion exchange membrane B is an anion exchange membrane. In the module stack 4, from the anode plate to the cathode plate, the module sequentially includes a plurality of anion exchange membranes B and cation exchange membranes A that are periodically alternately arranged, and each anion exchange membrane B and cation exchange membrane A forms a repeating unit. The repeating units formed by the multiple groups of ion exchange membranes separate a plurality of periodically alternately arranged amine liquid chambers II and waste liquid chambers III.

[0041] According to the present invention, when the membrane stack 4 is a bipolar membrane stack, the membrane stack 4 may include multiple groups of ion exchange membranes, each group of ion exchange membranes includes a bipolar membrane and an anion exchange membrane, forming a repeating unit, and the repeating unit formed by the multiple groups of ion exchange membranes separates multiple periodically alternately arranged amine liquid chambers II and waste liquid chambers III. The arrangement of the ion exchange membranes with different ion selective permeabilities in the membrane stack 4 can be the arrangement of bipolar membrane stacks conventional in the art, for example, the arrangement of the ion exchange membranes in the membrane stack 4 can be as follows Figure 2 As shown, in the module stack 4, the first ion exchange membrane A is a bipolar membrane, the second ion exchange membrane B is an anion exchange membrane, and the membrane stack 4 also includes a third ion exchange membrane C, which is a cation exchange membrane and is arranged close to the anode plate. In the module stack 4, from the third ion exchange membrane C to the cathode plate, the module group sequentially includes a plurality of anion exchange membranes B and bipolar membranes A arranged periodically and alternately, each anion exchange membrane B and bipolar membrane A forms a repeating unit, and the repeating unit formed by multiple groups of ion exchange membranes separates a plurality of periodically and alternately arranged amine liquid chambers II and waste liquid chambers III.

[0042] According to the present invention, the bipolar membrane is a composite ion exchange membrane composed of a cation exchange membrane and an anion exchange membrane. The bipolar membrane is characterized in that under the action of a DC electric field, H2O between the composite layers of the anion exchange membrane and the cation exchange membrane dissociates into H + and OH - And pass through the anion membrane and the cation membrane respectively, as H + and OH - The ion source works as follows Figure 2 shown.

[0043] According to the present invention, when the system for removing heat-stable salts in organic amine liquid provided by the present invention is used to treat an organic amine liquid containing heat-stable salts and containing a large number of strong cations, the membrane stack 4 can be a cationic membrane stack; when there is no metal cation in the organic amine liquid containing heat-stable salts, the membrane stack 4 can be a cationic membrane stack or a bipolar membrane stack, preferably a bipolar membrane stack. When the membrane stack is an organic amine liquid containing heat-stable salts and there is no metal cation, the membrane stack 4 is a cationic membrane stack, and the system further includes an alkali solution input device, which inputs alkali solution into the organic amine liquid to be treated, neutralizes the acidic substances in the organic amine liquid to be treated, and enriches the strong cations in the organic amine liquid to be treated, so as to avoid the removal of organic amine root ions and the loss of organic amine liquid.

[0044] According to the present invention, an organic amine liquid output pipeline is also connected to the organic amine liquid circulation loop, which is used to output the organic amine liquid from which the heat-stable salt is removed to the organic amine liquid reuse system, and a third regulating valve 63 is arranged on the organic amine liquid output pipeline. A waste liquid discharge pipeline is also connected to the desalted water circulation loop, which is used to discharge the desalted water enriched with heat-stable salt as waste liquid outside the system, and a fourth regulating valve 64 is arranged on the waste liquid discharge pipeline. The control center 5 is also used to receive the conductivity signal from the first conductivity meter 91 and / or the second conductivity meter 92, and adjust the opening of the third regulating valve 63 and / or the fourth regulating valve 64 according to the conductivity signal of the first conductivity meter 91 and / or the second conductivity meter 92. When the conductivity signals of the first conductivity meter 91 and / or the second conductivity meter 92 respectively meet the organic amine liquid reuse standard and / or the waste liquid discharge standard, the control center 5 controls the opening timing and / or opening degree of the third regulating valve 63 and / or the fourth regulating valve 64 respectively.

[0045] According to the present invention, a first circulation pump 71 is provided in the organic amine liquid circulation loop, a second circulation pump 72 is provided in the electrode liquid circulation loop, and a third circulation pump 73 is provided in the desalted water circulation loop, which are respectively used to circulate the material in the organic amine liquid storage device 1 into the amine liquid chamber II of the membrane stack 4, circulate the material in the electrode liquid storage device 2 into the anode chamber I-1 and cathode chamber I-2 of the membrane stack 4, and circulate the material in the desalted water storage device 3 into the waste liquid chamber III of the membrane stack 4. Preferably, a frequency converter is also provided in the first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 to control the switch and pump speed of each pump. More preferably, the starting speeds of the first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 are the same, the time from starting to normal operation of the first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 is 20-60s, more preferably 30-40s, and the time from normal operation to complete stop of the first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 is 0-20s, more preferably 5-10s. In addition, the frequency converter adjusts the flow rate of each material entering the membrane stack 4 by controlling the operating frequency of the first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 to ensure that the flow rate of each material is controllable.

[0046] Preferably, filters are also provided on the connecting pipelines from each circulation pump to the corresponding compartment of the membrane stack 4. The number of filters provided may be one or more to remove solid particles in the organic amine solution, desalted water and electrode solution.

[0047] According to the present invention, the solid particles in the organic amine solution, desalted water and electrode solution are dust, fine particles, equipment corrosion and detachment, degradation coke, reaction precipitates, etc. carried in the respective circulation processes. In order to remove the above solid particles, more preferably, the filter is a filter element filter, the filter element is a pp cotton folded cotton core, and the filtration accuracy is 0.1-1 micron.

[0048] Further preferably, the filter outlet is also provided with a differential pressure gauge to monitor the interception state of the filter element gap of the filter.

[0049] More preferably, a flow meter is also provided on the connecting pipeline from each circulation pump to the corresponding compartment of the membrane stack 4. The flow meter may be one or more, and a flow interruption detection device is provided on the flow meter. The membrane stack 4 generates heat during the power-on operation, and the generated heat is taken out of the membrane stack 4 and released as the materials circulate. When the material flow is interrupted, there is no material flow to cool the membrane stack, and the heat in the membrane stack 4 will continue to accumulate, causing the material in the membrane stack 4 to gradually heat up, or even boil, which may easily cause the membrane stack 4 to overheat or even burn. The flow interruption detection device can effectively detect the flow state of the material in the pipeline in each circulation loop. When the material in a pipeline is interrupted, the flow interruption detection device can feed back the flow interruption signal to the control center 5, and the control system cuts off the power supply of the membrane stack 4 to avoid overheating caused by continuous power on of the membrane stack 4.

[0050] According to the present invention, the organic amine liquid inlet, waste liquid inlet and electrode liquid inlet of the membrane stack 4 are respectively provided with a heat exchanger and a thermometer for regulating the temperature of the material entering the membrane stack 4. Preferably, after heat exchange by the heat exchanger, the temperature of the material entering the membrane stack 4 is 5-35°C, preferably 15-25°C. If the temperature of the material flowing into the membrane stack 4 is too high, it will destroy the effective ion exchange groups in the first ion exchange membrane A and the second ion exchange membrane B, and even destroy the structure of the first ion exchange membrane A and the second ion exchange membrane B. If the temperature of the material flowing into the membrane stack 4 is too low, it may cause the salt in each material to crystallize or the water to freeze, which may easily cause the deformation of the first ion exchange membrane A and the second ion exchange membrane B, and even destroy the structure of the first ion exchange membrane A and the second ion exchange membrane B, resulting in the liquid in different compartments being connected, resulting in the desalination capacity of the membrane stack 4 being reduced and the loss of organic amine liquid.

[0051] According to the present invention, the system may also be provided with an alkali liquid input device, the delivery pipeline of which is connected to the organic amine liquid storage device 1. A seventh regulating valve 67 is provided on the delivery pipeline of the alkali liquid input device, which is used to adjust the input timing and flow rate of the alkali liquid in the alkali liquid input device according to the type of organic amine liquid actually treated. According to the present invention, the alkali liquid may be but is not limited to sodium hydroxide and / or potassium hydroxide. When there is a lack of cations in the organic amine liquid to be treated, the alkali liquid may be supplemented as needed after the organic amine liquid is supplemented according to the actual situation, so as to avoid the loss of the organic amine liquid during the desalination process.

[0052] According to the present invention, the system is further provided with an inert gas access device, the delivery pipelines of which are respectively connected to the organic amine liquid storage device 1, the electrode liquid storage device 2 and the desalted water storage device 3, and the storage devices in each circulation loop are sealed with inert gas to ensure that the amine liquid and the like are isolated from the air in their respective circulation tanks and will not be oxidized. Preferably, the inert gas is nitrogen.

[0053] According to the present invention, a cleaning device is also provided in the membrane stack 4. When the electrodialysis efficiency of the first ion exchange membrane A and / or the second ion exchange membrane B in the membrane stack 4 decreases or is contaminated, the first ion exchange membrane A and / or the second ion exchange membrane B is cleaned to maintain the high desalination efficiency of the membrane stack 4.

[0054] Preferably, the organic amine liquid storage device 1 is further provided with an organic amine liquid level meter 81, and the desalted water storage device 2 is further provided with a desalted water level meter 82, which are respectively used to detect the liquid levels in the organic amine liquid storage device 1 and the desalted water storage device 2, and then send the liquid level signals of the two to the control center 5, and the control center 5 adjusts the fifth regulating valve 65 on the amine liquid input pipeline and / or the desalted water input pipeline according to the liquid level signals of the organic amine liquid level meter 81 and / or the desalted water level meter 82. The opening and switching timing of the sixth regulating valve 66 on the inlet pipeline can control the replenishment amount and flow rate of the organic amine liquid storage device 1 and the desalted water storage device 2; the control center 5 can also further control the opening and switching timing of the third regulating valve 63 and / or the fourth regulating valve 64 according to the liquid level signal of the organic amine liquid level meter 81 and / or the desalted water level meter 82, and coordinately control the circulation start or stop of the organic amine liquid in the organic amine liquid circulation loop and / or the waste liquid in the desalted water circulation loop and the circulation flow rate.

[0055] According to the present invention, in order to facilitate installation and simplify operation, the system is preferably a skid-mounted system.

[0056] The second aspect of the present invention provides a method for treating an organic amine liquid containing heat-stable salts by using the aforementioned system for removing heat-stable salts from an organic amine liquid, the method comprising introducing the organic amine liquid to be treated into an organic amine liquid storage device 1 of the system through an external pipeline, introducing deionized water into a deionized water storage device 3 of the system, introducing electrode liquid into an electrode liquid storage device 2, and then circulating the organic amine liquid into an amine liquid chamber II of the membrane stack 4, circulating the deionized water in the deionized water storage device 3 into a waste liquid chamber III of the membrane stack 4, and circulating the electrode liquid in the electrode liquid storage device 2 into a waste liquid chamber III of the membrane stack 4. Pump into the anode chamber I-1 and the cathode chamber I-2 of the membrane stack 4; connect the anode plate and the cathode plate of the membrane stack 4 to the positive and negative electrodes of the power supply respectively, so that the to-be-treated organic amine liquid circulated and pumped into the membrane stack 4 is subjected to heat-stable salt removal treatment to obtain an organic amine liquid removed from heat-stable salts and deionized water enriched in heat-stable salts, and when the obtained organic amine liquid removed from heat-stable salts and the deionized water enriched in heat-stable salts meet the recovery and discharge standards respectively, the organic amine liquid removed from heat-stable salts obtained after treatment is transported to the organic amine liquid reuse system, and the deionized water enriched in heat-stable salts obtained after treatment is discharged as waste liquid outside the system.

[0057] According to the present invention, preferably, the power supply connected to the anode plate and the cathode plate of the membrane stack 4 is a flameproof DC power supply.

[0058] According to the present invention, the current density generated after the anode plate and the cathode plate are connected to the power supply can be selected and set according to the concentration of the heat-stable salt in the organic amine solution to be treated and / or the conductivity of the organic amine solution. For example, when the concentration of the heat-stable salt in the organic amine solution to be treated is 0.5-10% by weight, or when the conductivity of the organic amine solution to be treated is 1-20 ms, the current density can be 5-400 mA / cm 2 The voltage and current of the power supply can be set according to the membrane area in the membrane stack 4. As long as the current density is controlled within 5-400 mA / cm 2 The number of ion exchange membranes in the membrane stack 4 can be 20-200 groups, and each group of ion exchange membranes includes two ion exchange membranes with different ion selective permeabilities to form a repeating unit. For example, when the membrane stack 4 is a cation membrane stack, a group of ion exchange membranes includes a cation exchange membrane and an anion exchange membrane, and when the membrane stack 4 is a bipolar membrane stack, a group of ion exchange membranes includes an anion exchange membrane and a bipolar membrane. When the membrane stack 4 is a cation membrane stack or a bipolar membrane stack, the working principle of the membrane stack 4 and the arrangement of the ion exchange membranes with different ion selective permeabilities therein are as described above and will not be repeated here. The size of the ion exchange membrane in the membrane stack 4 complies with relevant national and industry standards. In industry, 400mm×800mm ion exchange membranes are commonly used to assemble membrane stacks, and 200mm×400mm ion exchange membranes are also used to assemble membrane stacks. The present invention is not limited to the above two sizes of membrane stacks.

[0059] According to the present invention, when the organic amine liquid to be treated passes through the membrane stack 4 whose anode plate and cathode plate are respectively connected to the positive electrode and negative electrode of the power supply, the charged particles in the heat-stable salt in the organic amine liquid, driven by the external DC electric field, utilize the difference in ion selective permeability between the first ion exchange membrane A and the second ion exchange membrane B, that is, cations can pass through the cation exchange membrane, anions can pass through the anion exchange membrane, and vice versa, the uncharged organic amine liquid molecules cannot move through the anion and cation exchange membranes, but remain in the corresponding amine liquid chamber II. During the circulation of the organic amine liquid, the heat-stable salt is continuously removed, and the charged ions in the heat-stable salt are moved to the corresponding waste liquid chamber III. During the circulation of the desalted water, they are removed from the organic amine liquid, thereby achieving the purpose of desalination, concentration, refinement or purification of the organic amine liquid. In addition, the H2O between the composite layers of the anion and cation exchange membranes in the bipolar membrane dissociates into H + and OH - And pass through the anion membrane and the cation membrane respectively, as H + and OH -Ion source, when the heat-stable salt contained in the organic amine solution to be treated does not contain metal cations, the bipolar membrane can be used to generate H + It combines with the heat-stable salt anions removed from the organic amine solution to form acid, which is enriched in the deionized water and finally forms waste liquid which is discharged outside the system.

[0060] The organic amine solution described in the present invention exists in the form of molecules in the aqueous solution. It does not carry electrons by itself, and its conductivity completely depends on the heat-stable salt therein. However, as the purification process proceeds, the concentration of the heat-stable salt in the organic amine solution continues to decrease, and the conductivity of the organic amine solution will gradually decrease. Theoretically, when the concentration of the heat-stable salt decreases to 0 or close to 0, there are almost no mobile charged particles in the organic amine solution, which causes the conductivity of the organic amine solution to decrease or even be unable to conduct electricity. At this time, if the membrane stack 4 is still powered on, the current cannot pass or the power supply is blocked due to the decrease in the conductivity of the organic amine solution in the amine solution chamber II, which will cause serious consequences, such as: (1) the organic amine solution is ionized and enters the waste liquid chamber III, causing the loss of the organic amine solution, and further desalination cannot be completed; (2) it will cause the current efficiency to decrease, and the electrical energy will be further converted into thermal energy, resulting in an increase in the temperature of the organic amine solution, causing irreversible damage to the ion exchange membrane. The above problem can be circumvented by setting the discharge conductivity of the organic amine liquid, that is, the organic amine liquid is not discharged into the organic amine liquid reuse system when its conductivity is reduced to 0 or close to 0. However, the heat-stable salt in the organic amine liquid is continuously removed by the method of the present invention, and the heat-stable salt always reaches a very low level. In this case, once the heat-stable salt is removed, the above-mentioned consequences will occur, and the removal of the heat-stable salt can only be stopped. In other words, the concentration of the heat-stable salt cannot be reduced to a level close to 0 or reaching 0. In order to solve this problem, preferably, ion exchange resin is filled in the amine liquid chamber II of the electrodialysis. When the conductivity of the organic amine liquid decreases or even cannot conduct electricity, the ion exchange resin plays a role as a conductive medium, which can effectively promote the electrodialysis process and improve the electrodialysis desalination efficiency and desalination depth.

[0061] According to the present invention, the selection and dosage of the ion exchange resin are as described above and will not be repeated here.

[0062] According to the present invention, the organic amine liquid to be treated can be at least one of monoethanolamine containing a heat-stable salt, diethanolamine containing a heat-stable salt, N-methyldiethanolamine containing a heat-stable salt, triethanolamine containing a heat-stable salt, N-methylethylenediamine containing a heat-stable salt, diisopropanolamine containing a heat-stable salt, N,N-dibutylethanolamine containing a heat-stable salt, ethylenediamine containing a heat-stable salt, diethylamine containing a heat-stable salt, tetramethylethylenediamine containing a heat-stable salt, and piperazine containing a heat-stable salt.

[0063] For example, MDEA is often used as a desulfurizer for the desulfurization of liquefied gas in refineries. The desulfurizer will be partially degraded and oxidized to produce formate and acetate during the recycling process. The sulfide produced by desulfurization will also be oxidized to sulfate, sulfite, thiosulfate, etc. These anions can exist stably at the regeneration temperature of the desulfurizer, which is the so-called heat stable salt (HSS). Heat stable salts will continue to accumulate in the amine solution, causing the amine solution to foam, darken in color, and corrode, which further promotes the deterioration and degradation of the amine solution, forming a vicious cycle, and ultimately affecting the desulfurization depth and desulfurization efficiency of the amine solution. What's more, some refineries introduce strong cations (such as Na + , K + , Ca 2+ Mg 2+ Strong cations will form thermally stable sulfides during the desulfurization process, causing the hydrogen sulfide content of the lean amine liquid to increase, affecting the desulfurization depth and desulfurization efficiency, resulting in unqualified desulfurization.

[0064] The method for treating an organic amine liquid containing heat-stable salts by using the system for removing heat-stable salts from an organic amine liquid of the present invention can simultaneously remove strong cations and heat-stable salt anions in the organic amine liquid to be treated (for example, sodium ions and acetate ions are removed simultaneously to form sodium acetate), and accumulate them in the desalted water to a certain concentration before being discharged.

[0065] According to the present invention, the organic amine solution, desalted water and electrode solution are subjected to heat exchange treatment before entering the membrane stack 4. The temperature of the organic amine solution, desalted water and electrode solution after heat exchange treatment is 5-35°C, preferably 15-25°C.

[0066] According to the present invention, the organic amine solution, desalted water and electrode solution are filtered before entering the membrane stack 4 to remove solid particles with a particle size of 0.1-1 micron in the organic amine solution, desalted water and electrode solution.

[0067] According to the present invention, preferably, during the treatment process of the organic amine solution, the flow rate of the organic amine solution and the desalted water can be 1-10m 3 / h, preferably 2-5m 3 / h, the flow rate of the electrode liquid can be 1-5m 3 / h, preferably 2-4m 3 Before entering the membrane stack 4, the organic amine solution, deionized water and electrode solution are divided into multiple branches, each of which enters a corresponding compartment in the membrane stack 4, and the flow rate of each branch remains unchanged or is evenly distributed to the same flow rate.

[0068] The present invention will be described in detail below through examples.

[0069] Example 1

[0070] The system for removing heat-stable salt from organic amine solution provided in this embodiment is a skid-mounted system, and its structural schematic diagram is as follows: Figure 1 As shown, the system includes: an organic amine liquid storage device 1, an electrode liquid storage device 2, a desalted water storage device 3, a membrane stack 4 and a control center 5, wherein the membrane stack 4 is connected to the organic amine liquid storage device 1, the electrode liquid storage device 2 and the desalted water storage device 3 respectively; the membrane stack 4 is provided with at least one organic amine liquid inlet, an organic amine liquid outlet, a waste liquid inlet, a waste liquid outlet, an electrode liquid inlet and an electrode liquid outlet; the organic amine liquid outlet and the waste liquid outlet are respectively provided with a first conductivity meter 91 and a second conductivity meter 92 for monitoring the conductivity of the organic amine liquid outlet and the waste liquid outlet. Liquid conductivity at the waste liquid outlet; a first regulating valve 61 is arranged on the material conveying pipeline between the organic amine liquid outlet and the organic amine liquid storage device 1, and a second regulating valve 62 is arranged on the material conveying pipeline between the desalted water storage device 3 and the waste liquid inlet; the system also includes a control center 5 for receiving conductivity signals from the first conductivity meter 91 and / or the second conductivity meter 92, and adjusting the opening of the first regulating valve 61 and / or the second regulating valve 62 according to the conductivity signals of the first conductivity meter 91 and / or the second conductivity meter 92.

[0071] The membrane stack 4 comprises an anode plate and a cathode plate which are arranged at both ends of the membrane stack 4 and a module containing a plurality of ion exchange membranes which are arranged between the anode plate and the cathode plate; the area between the anode plate and the module forms an anode chamber I-1, and the area between the cathode plate and the module forms a cathode chamber I-2; the plurality of ion exchange membranes separate a plurality of periodically alternately arranged amine liquid chambers II and waste liquid chambers III in the module; the ion selective permeability of two adjacent ion exchange membranes is different; the organic amine liquid inlet and the organic amine liquid outlet are arranged on the opposite sides of each of the amine liquid chambers II, the waste liquid inlet and the waste liquid outlet are arranged on the opposite sides of each of the waste liquid chambers III, and the electrode liquid outlet and the electrode liquid outlet are respectively arranged on the opposite sides of the anode chamber I-1 and the cathode chamber I-2; the liquid outlet of the organic amine liquid storage device 1 The inlet of the organic amine liquid storage device 1 is connected with the organic amine liquid inlet of the amine liquid chamber II of the membrane stack 4, and the liquid inlet of the organic amine liquid storage device 1 is connected with the organic amine liquid outlet of the amine liquid chamber II of the membrane stack 4, so as to form a closed loop, which becomes an organic amine liquid circulation loop; the electrode liquid outlet of the electrode liquid storage device 2 is connected with the electrode liquid inlet of the anode chamber I-1 and the cathode chamber I-2, and the electrode liquid inlet of the electrode liquid storage device 2 is connected with the electrode liquid outlet of the anode chamber I-1 and the cathode chamber I-2, so as to form a closed loop, which becomes an electrode liquid circulation loop; the desalted water outlet of the desalted water storage device 3 is connected with the waste liquid inlet of the waste liquid chamber III, and the desalted water inlet of the desalted water storage device 3 is connected with the waste liquid outlet of the waste liquid chamber III, so as to form a closed loop, which becomes a desalted water circulation loop.

[0072] An organic amine liquid output pipeline is also connected to the organic amine liquid circulation loop, which is used to output the organic amine liquid from which the heat-stable salt is removed to the organic amine liquid recycling system for removing the heat-stable salt. A third regulating valve 63 is arranged on the amine liquid output pipeline. A waste liquid discharge pipeline is also connected to the desalted water storage device 3, which is used to discharge the waste liquid outside the system. A fourth regulating valve 64 is arranged on the waste liquid discharge pipeline. The control center 5 is also used to receive conductivity signals from the first conductivity meter 91 and the second conductivity meter 92, and adjust the opening of the third regulating valve 63 and the fourth regulating valve 64 according to the conductivity signals of the first conductivity meter 91 and the second conductivity meter 92.

[0073] The organic amine liquid circulation loop is provided with a first circulation pump 71, the electrode liquid circulation loop is provided with a second circulation pump 72, and the desalted water circulation loop is provided with a third circulation pump 73, which are respectively used to circulate the material in the organic amine liquid storage device 1 into the amine liquid chamber II of the membrane stack 4, circulate the material in the electrode liquid storage device 2 into the anode chamber I-1 and cathode chamber I-2 of the membrane stack 4, and circulate the material in the desalted water storage device 3 into the waste liquid chamber III of the membrane stack 4. The first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 are also provided with a frequency converter for controlling the switch and pump speed of each pump. The first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 have the same starting speed, and the time from starting to normal operation is 35s. The time from normal operation to complete stop of the first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 is the same, which is 5s.

[0074] A filter is also provided on the connecting pipeline from each circulation pump to the corresponding compartment of the membrane stack 4. The filter is a filter element type filter, the filter element is a pp cotton folded cotton core, and the filtering accuracy is 0.1 micron.

[0075] The filter outlet is also provided with a differential pressure gauge to monitor the interception state of the filter element gap of the filter.

[0076] A flow meter is also provided on the connecting pipeline from each circulation pump to the corresponding compartment of the membrane stack 4, and a flow interruption detection device is provided on the flow meter.

[0077] Heat exchangers and thermometers are respectively provided at the organic amine liquid inlet, waste liquid inlet and electrode liquid inlet of the membrane stack 4 to adjust the temperature of the material entering the membrane stack 4 to 20°C.

[0078] The system is also provided with a nitrogen generating device, the delivery pipelines of which are respectively connected to the organic amine liquid storage device 1, the electrode liquid storage device 2 and the desalted water storage device 3, and the storage devices in each circulation loop are nitrogen-sealed to ensure that the amine liquid and the like are isolated from the air in their respective circulation tanks and will not be oxidized.

[0079] The membrane stack 4 is also provided with a cleaning device for cleaning the first ion exchange membrane A and / or the second ion exchange membrane B.

[0080] The organic amine liquid storage device 1 is also provided with an organic amine liquid level meter 81, and the desalted water storage device 2 is also provided with a desalted water level meter 82, which are respectively used to detect the liquid levels in the organic amine liquid storage device 1 and the desalted water storage device 2, and then send the liquid level signals of the two to the control center 5. The control center 5 adjusts the opening of the fifth regulating valve 65 on the amine liquid input pipeline and / or the sixth regulating valve 66 on the desalted water input pipeline according to the liquid level signals of the organic amine liquid level meter 81 and / or the desalted water level meter 82, thereby controlling the amount and flow rate of the replenishment of the organic amine liquid storage device 1 and / or the desalted water storage device 2; the control center 5 can also further control the opening and switching timing of the third regulating valve 63 and / or the fourth regulating valve 64 according to the liquid level signals of the organic amine liquid level meter 81 and / or the desalted water level meter 82, and coordinately control the circulation start or stop of the organic amine liquid in the organic amine liquid circulation loop and / or the waste liquid in the desalted water circulation loop and the circulation flow rate.

[0081] When the aforementioned system for removing heat-stable salts from organic amine liquid is used to treat an organic amine liquid containing heat-stable salts, the organic amine liquid to be treated is introduced into the organic amine liquid storage device 1 of the system through an external pipeline, the deionized water is introduced into the deionized water storage device 3 of the system, the electrode liquid is introduced into the electrode liquid storage device 2, and then the organic amine liquid is circulated and pumped into the amine liquid chamber II of the membrane stack 4, the deionized water in the deionized water storage device 3 is circulated and pumped into the waste liquid chamber III of the membrane stack 4, and the electrode liquid in the electrode liquid storage device 2 is circulated and pumped into the anode chamber I of the membrane stack 4. -1 and cathode chamber I-2; the anode plate and cathode plate of the membrane stack 4 are respectively connected to the positive and negative electrodes of a flameproof DC power supply, so that the organic amine liquid to be treated which is circulated and pumped into the membrane stack 4 is treated to remove heat-stable salts, so as to obtain an organic amine liquid removed from heat-stable salts and a deionized water enriched in heat-stable salts, and when the obtained organic amine liquid removed from heat-stable salts and the deionized water enriched in heat-stable salts meet the recovery and discharge standards respectively, the organic amine liquid removed from heat-stable salts obtained after treatment is transported to an organic amine liquid reuse system, and the deionized water enriched in heat-stable salts obtained after treatment is discharged as waste liquid outside the system.

[0082] In this embodiment, the organic amine liquid to be treated is taken from Dalian West Pacific Petrochemical Co., Ltd., and its composition is shown in Table 1. The membrane stack 4 is a cation-cation membrane stack, and its structural schematic diagram and working principle are shown in Table 1. Figure 1As shown, the first ion exchange membrane A is a cation exchange membrane, the second ion exchange membrane B is an anion exchange membrane, the anion and cation membrane stack includes 100 groups of cation exchange membranes and anion exchange membranes arranged alternately in a periodic manner, and from the anode plate to the cathode plate, the module includes a plurality of anion exchange membranes B and cation exchange membranes A arranged alternately in a periodic manner in sequence, each anion exchange membrane B and cation exchange membrane A forms a repeating unit, and the repeating unit formed by the plurality of groups of ion exchange membranes separates a plurality of periodically alternately arranged amine liquid chambers II and waste liquid chambers III. The deionized water is deionized water, and the electrode liquid is a sodium sulfate solution with a concentration of 6% by weight. The first circulation pump 71, the second circulation pump 72 and the third circulation pump 73 are provided with a frequency converter, and the frequency of the frequency converter setting is 29Hz, and the circulation flow rate of the organic amine liquid and the deionized water is controlled to be 4m 3 / h, the pump out flow rate of electrode liquid is 2m 3 / h, and the branch flow rates into the anode chamber I-1 and cathode chamber I-2 are both 1m 3 / h, the flameproof DC power supply has a voltage of 130V, a current of 110A, and a current density of 150mA / cm 2 The control center 5 sets the conductivity signal difference of the organic amine liquid to 10ms, and the conductivity signal value of the desalted water discharged as waste liquid to 55ms. When the conductivity signal difference measured by the first conductivity meter 91 is 10ms, the control center 5 regulates the first regulating valve 61 to close, and opens the third regulating valve 63 provided on the output pipeline of the organic amine liquid, and outputs the treated organic amine liquid that meets the standard to the organic amine liquid recycling system. When the conductivity signal value of the amine liquid measured by the second conductivity meter 92 is 55ms, the control center 5 regulates the second regulating valve 62 to close, and opens the fourth regulating valve 64 provided on the waste liquid discharge pipeline, and discharges the desalted water enriched with heat-stable salt as waste liquid out of the system.

[0083] The treated organic amine solution and desalted water were tested, and the test results are shown in Table 1.

[0084] Table 1

[0085] sample Organic amine solution concentration Conductivity <![CDATA[Na + Concentration]]> <![CDATA[Cl - Concentration]]> Heat stable salt concentration Organic amine liquid to be treated 25.5 wt% 14ms 8300mg / L 15240mg / L 6.69 wt% Treated organic amine liquid 26.19 wt% 4ms 600mg / L 1160mg / L 0.75 wt% Desalinated water - 55ms 16600mg / L 31640mg / L 12.87 wt%

[0086] It can be seen from Table 1 that the conductivity of the organic amine liquid is reduced after treatment, and the concentrations of sodium ions, chloride ions and heat-stable salts decrease, while the conductivity of the deionized water increases from 0 (deionized water) to 55 ms, and the concentration of heat-stable salts reaches 12.87% by weight, indicating that the heat-stable salts in the organic amine liquid to be treated enter the deionized water under the action of the DC electric field, and the deionized water enriched with the heat-stable salts is discharged as waste liquid, thereby achieving the purpose of removing the heat-stable salts in the organic amine liquid.

[0087] Example 2

[0088] The system for removing heat-stable salts from organic amine solution provided in this embodiment and the method for treating organic amine solution containing heat-stable salts using the system for removing heat-stable salts from organic amine solution provided in this embodiment are as in Example 1, except that the membrane stack 4 is a bipolar membrane stack, and its structural schematic diagram and working principle are as shown in FIG. Figure 2 As shown, the first ion exchange membrane A is a bipolar membrane, the second ion exchange membrane B is an anion exchange membrane, the bipolar membrane stack includes 100 groups of bipolar membranes and anion exchange membranes and a third ion exchange membrane C that are periodically alternately arranged, the third ion exchange membrane C is a cation exchange membrane, which is arranged close to the anode plate, and from the third ion exchange membrane C to the cathode plate, the module sequentially includes a plurality of anion exchange membranes B and bipolar membranes A that are periodically alternately arranged, each anion exchange membrane B and bipolar membrane A form a repeating unit, and the repeating unit formed by the plurality of groups of ion exchange membranes separates a plurality of periodically alternately arranged amine liquid chambers II and waste liquid chambers III. The control center 5 sets the conductivity signal difference of the organic amine liquid to 15ms, and the conductivity signal value of the desalted water discharged as waste liquid to 55ms. When the conductivity signal difference measured by the first conductivity meter 91 is 15ms, the control center 5 controls the first regulating valve 61 to close, and opens the third regulating valve 63 provided on the output pipeline of the organic amine liquid, and outputs the treated organic amine liquid that meets the standards to the organic amine liquid recycling system. When the amine liquid conductivity signal value measured by the second conductivity meter 92 is 55ms, the control center 5 controls the second regulating valve 62 to close, and opens the fourth regulating valve 64 provided on the waste liquid discharge pipeline, and discharges the desalted water enriched with heat-stable salt as waste liquid out of the system.

[0089] The organic amine solution to be treated is an industrial pure MDEA self-prepared (hydrochloric acid is added to the amine solution) organic amine solution, and its composition is shown in Table 2. The treated organic amine solution and deionized water are taken for detection, and the detection results are shown in Table 2.

[0090] Table 2

[0091] sample Organic amine solution concentration Conductivity Metal cation concentration <![CDATA[Cl - Concentration]]> Organic amine liquid to be treated 25% by weight 18.8ms 0mg / L 20000mg / L Treated organic amine liquid 25 wt% 3.8ms 0mg / L 800mg / L Desalinated water - 55ms 0mg / L 35870mg / L

[0092] It can be seen from Table 2 that the conductivity of the organic amine solution decreased after treatment, the chloride ion concentration decreased, and the conductivity of the deionized water increased from 0 (deionized water) to 55ms. The main component of the deionized water is hydrochloric acid, in which the chloride ion content is 35870mg / L, indicating that under the action of the bipolar membrane, the chloride ions in the organic amine solution to be treated react with the H generated by the bipolar membrane. + Combined with desalinated water storage device, forming hydrochloric acid, and the OH produced by the bipolar membrane - It enters the organic amine liquid circulation loop to neutralize the hydrochloric acid added to the organic amine liquid to be treated, thereby achieving the purpose of removing the heat-stable salt in the organic amine liquid to be treated.

[0093] Example 3

[0094] The system for removing heat-stable salts from organic amine solution provided in this embodiment and the method for treating organic amine solution containing heat-stable salts by using the system for removing heat-stable salts from organic amine solution provided in this embodiment are as described in Example 1, except that the system is further provided with an alkali solution input device, and the liquid outlet of the alkali solution input device is connected to the organic amine solution inlet of the membrane stack 4. The alkali solution is sodium hydroxide, and the concentration of the alkali solution is 30% by weight.

[0095] The organic amine solution to be treated is an industrial pure MDEA self-prepared (hydrochloric acid is added to the amine solution) organic amine solution, and its composition is shown in Table 3. The treated organic amine solution and deionized water are taken for detection, and the detection results are shown in Table 3.

[0096] Table 3

[0097]

[0098] It can be seen from Table 3 that the conductivity of the treated organic amine solution decreases, the concentrations of sodium ions, chloride ions and heat-stable salts decrease, and the conductivity of the deionized water increases from 0 (deionized water) to 55ms, indicating that when there is no metal cation in the organic amine solution to be treated, the heat-stable salts of the organic amine solution to be treated can be removed by adding alkali solution, that is, a cation-cation membrane stack can be used to remove the heat-stable salts, thereby achieving the same desalination effect as that of the organic amine solution containing metal cations, and the treated organic amine solution will not cause the loss of the organic amine solution.

[0099] Example 4

[0100] The system for removing heat-stable salts from an organic amine liquid provided in this embodiment and the method for treating an organic amine liquid containing heat-stable salts using the system for removing heat-stable salts from an organic amine liquid are as described in Example 1, except that in the cation-cation membrane stack used, the amine liquid chamber II is filled with a mixture of a hydroxide-type strong alkaline anion exchange resin and a sodium-type cation exchange resin in a volume ratio of 1:1.

[0101] The control center 5 sets the conductivity signal value of the organic amine liquid discharge to 0ms, and the conductivity signal value of the desalted water discharged as waste liquid to 55ms. When the conductivity signal value of the amine liquid measured by the first conductivity meter 91 is 0ms, the control center 5 regulates the first regulating valve 61 to close, and opens the third regulating valve 63 provided on the output pipeline of the organic amine liquid, and outputs the treated organic amine liquid that meets the standards to the organic amine liquid recycling system. When the conductivity signal value of the amine liquid measured by the second conductivity meter 92 is 55ms, the control center 5 regulates the second regulating valve 62 to close, and opens the fourth regulating valve 64 provided on the waste liquid discharge pipeline, and discharges the desalted water enriched with heat-stable salt as waste liquid out of the system.

[0102] The treated organic amine liquid and waste liquid were tested, and the test results are shown in Table 4.

[0103] Table 4

[0104] sample Organic amine solution concentration Conductivity <![CDATA[Na + Concentration]]> <![CDATA[Cl - Concentration]]> Heat stable salt concentration Organic amine liquid to be treated 25.5 wt% 14ms 8300mg / L 15240mg / L 6.69 wt% Treated organic amine liquid 26.3 wt% 0ms <10mg / L <10mg / L 0% by weight Desalinated water - 55ms 16880mg / L 32100mg / L 13.1 wt%

[0105] It can be seen from Table 4 that under the action of ion exchange resin as a conductive medium, the electrodialysis desalination depth is improved. Under the same treatment conditions, the concentrations of sodium ions, chloride ions and heat-stable salts in the treated organic amine solution drop to near 0, while the conductivity of the deionized water increases from 0 (deionized water) to 55 ms, and the concentration of heat-stable salts reaches 13.1% by weight, indicating that the heat-stable salts in the organic amine solution to be treated almost all enter the desalted water under the action of the DC electric field, and the desalted water enriched with heat-stable salts is discharged as waste liquid, thereby achieving the purpose of deep removal of heat-stable salts in the organic amine solution.

[0106] Example 5

[0107] The system for removing heat-stable salts from organic amine liquid provided in this embodiment and the method for treating organic amine liquid containing heat-stable salts using the system for removing heat-stable salts from organic amine liquid are as in Example 2, except that in the bipolar membrane stack used, the amine liquid chamber II is filled with a strong alkaline anion exchange resin of the hydroxide type.

[0108] The control center 5 sets the conductivity signal value of the organic amine liquid discharge to 0ms, and the conductivity signal value of the desalted water discharged as waste liquid to 55ms. When the conductivity signal value of the amine liquid measured by the first conductivity meter 91 is 0ms, the control center 5 regulates the first regulating valve 61 to close, and opens the third regulating valve 63 provided on the output pipeline of the organic amine liquid, and outputs the treated organic amine liquid that meets the standards to the organic amine liquid recycling system. When the conductivity signal value of the amine liquid measured by the second conductivity meter 92 is 55ms, the control center 5 regulates the second regulating valve 62 to close, and opens the fourth regulating valve 64 provided on the waste liquid discharge pipeline, and discharges the desalted water enriched with heat-stable salt as waste liquid out of the system.

[0109] The treated organic amine solution and desalted water were tested, and the test results are shown in Table 5.

[0110] Table 5

[0111] sample Organic amine solution concentration Conductivity Metal cation concentration <![CDATA[Cl - Concentration]]> Organic amine liquid to be treated 25 wt% 18.8ms 0mg / L 20000mg / L Treated organic amine liquid 25 wt% 0ms 0mg / L <10mg / L Desalinated water - 55ms 0mg / L 35590mg / L

[0112] It can be seen from Table 5 that under the action of ion exchange resin as a conductive medium, the electrodialysis desalination depth is improved. Under the same treatment conditions, the chloride ion concentration in the treated organic amine solution drops to close to 0, while the conductivity of the deionized water increases from 0 (deionized water) to 55ms, indicating that the heat-stable salts in the organic amine solution to be treated almost all enter the deionized water under the action of the DC electric field, and the deionized water enriched with the heat-stable salts is discharged as waste liquid, achieving the purpose of deep removal of the heat-stable salts in the organic amine solution.

[0113] It can be seen from the results of Tables 1-5 that the system for removing heat-stable salts from organic amine liquid provided by the present invention is suitable for treating organic amine liquids containing different heat-stable salts, has a high degree of automation, strong desalting capacity, and does not require manual intervention throughout the process, thus saving labor costs. The use of the system to treat organic amine liquids containing heat-stable salts can not only achieve the simultaneous removal of anions and cations in the amine liquid, but also effectively remove solid particulate matter in the organic amine liquid, greatly reduce the consumption of alkali liquid, reduce the amount of waste liquid discharged, and enhance the reproducible service life of the organic amine liquid.

[0114] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A system for removing heat-stable salts from an organic amine solution, the system comprising: An organic amine liquid storage device (1), an electrode liquid storage device (2), a desalted water storage device (3), a membrane stack (4) and a control center (5), characterized in that the membrane stack (4) is respectively connected to the organic amine liquid storage device (1), the electrode liquid storage device (2) and the desalted water storage device (3); the membrane stack (4) is provided with at least one organic amine liquid inlet, an organic amine liquid outlet, a waste liquid inlet, a waste liquid outlet, an electrode liquid inlet and an electrode liquid outlet; a first conductivity meter (91) and a second conductivity meter (92) are respectively provided at the organic amine liquid outlet and the waste liquid outlet for monitoring the liquid conductivity at the organic amine liquid outlet and the waste liquid outlet; a first regulating valve (61) is provided on the material conveying pipeline between the organic amine liquid outlet and the organic amine liquid storage device (1); and a first regulating valve (61) is provided on the material conveying pipeline between the desalted water storage device (3) and the waste liquid inlet. A second regulating valve (62) is arranged on the membrane stack (4); the control center (5) is used to receive the conductivity signal from the first conductivity meter (91) and / or the second conductivity meter (92), and adjust the opening of the first regulating valve (61) and / or the second regulating valve (62) according to the conductivity signal from the first conductivity meter (91) and / or the second conductivity meter (92); the membrane stack (4) comprises an anode plate and a cathode plate arranged at two ends of the membrane stack (4) relative to each other, and a membrane group containing multiple ion exchange membranes arranged between the anode plate and the cathode plate; the area between the anode plate and the membrane group forms an anode chamber (I-1), and the area between the cathode plate and the membrane group forms a cathode chamber (I-2); the multiple ion exchange membranes separate multiple amine liquid chambers (II) and waste liquid chambers (III) arranged periodically and alternately in the membrane group; the ion selective permeability of two adjacent ion exchange membranes is different; Ion exchange resin is also filled between the two ion exchange membranes of each amine liquid chamber (II) separated in the membrane stack (4); the ion exchange resin is a strongly acidic cation exchange resin and a strongly basic anion exchange resin; the volume ratio of the strongly acidic cation exchange resin to the strongly basic anion exchange resin is 1:0.5-2.

2. The system according to claim 1, wherein: The organic amine liquid inlet and the organic amine liquid outlet are arranged on the opposite sides of each of the amine liquid chambers (II), the waste liquid inlet and the waste liquid outlet are arranged on the opposite sides of each of the waste liquid chambers (III), and the electrode liquid inlet and the electrode liquid outlet are arranged on the opposite sides of the anode chamber (I-1) and the cathode chamber (I-2); The organic amine liquid storage device (1) is provided with a liquid inlet and a liquid outlet, the liquid outlet is connected to the organic amine liquid inlet, and the liquid inlet is connected to the organic amine liquid outlet, so as to form an organic amine liquid circulation loop; The electrode liquid storage device (2) is provided with an electrode liquid inlet and an electrode liquid outlet, the electrode liquid outlet is communicated with the electrode liquid inlet, and the electrode liquid inlet is communicated with the electrode liquid outlet, so as to form an electrode liquid circulation loop; The desalted water storage device (3) is provided with a desalted water inlet and a desalted water outlet, the desalted water outlet is connected to the waste liquid inlet, and the desalted water inlet is connected to the waste liquid outlet, forming a desalted water circulation loop.

3. The system according to claim 2, wherein: The membrane stack (4) is a cation-cation membrane stack or a bipolar membrane stack, and the two adjacent ion exchange membranes with different selective permeabilities in the membrane stack (4) include a first ion exchange membrane (A) and a second ion exchange membrane (B); When the membrane stack (4) is a cation-cation membrane stack, the first ion exchange membrane (A) and the second ion exchange membrane (B) are each an anion exchange membrane or a cation exchange membrane; when the membrane stack (4) is a bipolar membrane stack, the first ion exchange membrane (A) and the second ion exchange membrane (B) are each an anion exchange membrane or a bipolar membrane.

4. The system according to claim 2, wherein: The organic amine liquid circulation loop is also connected to an organic amine liquid output pipeline for outputting the organic amine liquid from which the heat-stable salt has been removed to an organic amine liquid recycling system, and a third regulating valve (63) is arranged on the organic amine liquid output pipeline. The deionized water circulation loop is also connected to a waste liquid discharge pipeline for discharging the waste liquid outside the system, and a fourth regulating valve (64) is arranged on the waste liquid discharge pipeline. The control center (5) is also used to receive a conductivity signal from the first conductivity meter (91) and / or the second conductivity meter (92), and to adjust the opening of the third regulating valve (63) and / or the fourth regulating valve (64) according to the conductivity signal from the first conductivity meter (91) and / or the second conductivity meter (92).

5. The system according to claim 4, wherein: The organic amine liquid circulation loop is provided with a first circulation pump (71), the electrode liquid circulation loop is provided with a second circulation pump (72), and the desalted water circulation loop is provided with a third circulation pump (73), which are respectively used to circulate the material in the organic amine liquid storage device (1) into the amine liquid chamber (II) of the membrane stack (4), circulate the material in the electrode liquid storage device (2) into the anode chamber (I-1) and cathode chamber (I-2) of the membrane stack (4), and circulate the material in the desalted water storage device (3) into the waste liquid chamber (III) of the membrane stack (4).

6. The system according to claim 5, wherein: A filter is also provided on the connecting pipelines from each circulation pump to the corresponding compartment of the membrane stack (4).

7. The system according to claim 6, wherein: The filter is a cartridge filter with a filtering accuracy of 0.1-1 micron.

8. The system according to any one of claims 1 to 7, wherein: Heat exchangers and thermometers are respectively provided at the organic amine liquid inlet, the waste liquid inlet and the electrode liquid inlet of the membrane stack (4) for regulating the temperature of the material entering the membrane stack (4).

9. The system according to any one of claims 2 to 7, wherein: The system is also provided with an alkali solution input device, the delivery pipeline of which is connected to the organic amine solution storage device (1).

10. The system according to any one of claims 2 to 7, wherein: The system is also provided with an inert gas access device, the delivery pipelines of which are respectively connected to the organic amine liquid storage device (1), the electrode liquid storage device (2) and the desalted water storage device (3).

11. A method for treating an organic amine solution containing heat-stable salts by using the system for removing heat-stable salts from an organic amine solution according to any one of claims 1 to 10, characterized in that: The method comprises introducing the organic amine liquid to be treated into the organic amine liquid storage device (1) of the system through an external pipeline, introducing deionized water into the deionized water storage device (3) of the system, introducing the electrode liquid into the electrode liquid storage device (2), and then circulating the organic amine liquid into the amine liquid chamber (II) of the membrane stack (4), circulating the deionized water in the deionized water storage device (3) into the waste liquid chamber (III) of the membrane stack (4), and circulating the electrode liquid in the electrode liquid storage device (2) into the anode chamber (I-1) and the anode chamber (I-2) of the membrane stack (4). The cathode chamber (I-2) connects the anode plate and cathode plate of the membrane stack (4) to the positive and negative electrodes of the power supply, respectively, so that the organic amine liquid to be treated that is circulated and pumped into the membrane stack (4) is subjected to heat-stable salt removal treatment to obtain an organic amine liquid removed from heat-stable salts and a deionized water enriched in heat-stable salts. When the obtained organic amine liquid removed from heat-stable salts and the deionized water enriched in heat-stable salts meet the recovery and discharge standards, respectively, the organic amine liquid removed from heat-stable salts obtained after treatment is transported to an organic amine liquid recycling system, and the deionized water enriched in heat-stable salts obtained after treatment is discharged as waste liquid to the outside of the system.

12. The method according to claim 11, wherein: The organic amine liquid to be treated is at least one of monoethanolamine containing a heat-stable salt, diethanolamine containing a heat-stable salt, N-methyldiethanolamine containing a heat-stable salt, triethanolamine containing a heat-stable salt, N-methylethylenediamine containing a heat-stable salt, diisopropanolamine containing a heat-stable salt, N,N-dibutylethanolamine containing a heat-stable salt, ethylenediamine containing a heat-stable salt, diethylamine containing a heat-stable salt, tetramethylethylenediamine containing a heat-stable salt, and piperazine containing a heat-stable salt.

13. The method according to claim 11 or 12, wherein: The organic amine solution, desalted water and electrode solution are subjected to heat exchange treatment before entering the membrane stack (4). The temperature of the organic amine solution, desalted water and electrode solution after the heat exchange treatment is 5-35°C.

14. The method according to claim 13, wherein: The temperature of the organic amine solution, desalted water and electrode solution after heat exchange treatment is 15-25°C.

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