Refining desulfurization amine liquid purification system

Abstract

The invention discloses a refining desulfurization amine liquid purification system. The system comprises a pretreatment system, an electrodialysis system, and an electromechanical control system and a valve pipeline system which are matched and affiliated, the electrodialysis system comprises a membrane separation stack as well as a fresh water device, an electrode water device, a water production device and a concentrated water device which are connected to the membrane separation stack; the membrane separation stack comprises an anode plate, a membrane stack, a cathode plate and a fixing plate for fixing the membrane separation stack; the membrane stack comprises ion exchange membranes and partition plates; the ion exchange membranes comprise cation exchange membranes and anion exchange membranes; the cation exchange membranes and the anion exchange membranes are alternately arranged. The invention aims to reduce the wastewater generation amount, reduce the MDEA (methyldiethanolamine) entrainment loss and reduce the regeneration energy consumption through an electrodialysis technology; meanwhile, waste alkali liquor caused by electrodialysis can be reduced, the production cost is reduced, and the quality of downstream products is stabilized.

Description

Technical Field

[0001] The invention relates to the technical field of amine liquid desulfurization, in particular to a refining desulfurization amine liquid purification system. Background Art

[0002] The refinery amine desulfurization system is an important auxiliary unit for the refinery to purify sulfur-containing gas to meet process or fuel requirements. The energy consumption and agent consumption of the amine desulfurization system are important components of the refinery cost accounting.

[0003] At present, the most widely recognized and widely used desulfurization method in refineries is the alcohol amine method. However, in the production process of the alcohol amine method desulfurization process, as the operating time of the amine liquid system increases, the impurities in it continue to accumulate and the concentration of heat-stable salts in the amine liquid continues to increase. As the solid impurity content increases, the amine liquid filter will be blocked, and the filter core needs to be frequently flushed and replaced. The increase in the content of fine solid impurities will cause the amine liquid to foam more, affecting the quality of downstream products. At the same time, the removal effect of solid impurities directly affects the operating quality of the back-end electrodialysis desalination module, which will cause the blockage of the electrodialysis module membrane stack and even cause the increase in energy consumption and agent consumption of the desulfurization system, resulting in an increase in production costs.

[0004] In view of the problem that the amine liquid quality in the amine liquid desulfurization system of the refinery is "rich liquid but not rich", the electrodialysis membrane stack desalination technology has been proposed, which can effectively reduce the amount of wastewater generated, reduce the entrainment loss of MDEA (methyldiethanolamine, used for acid gas purification, a high-efficiency and low-energy decarbonization solvent), and reduce the regeneration energy consumption. Among them, the electrodialysis desalination technology is an emerging high-efficiency membrane separation technology characterized by the selective permeation of ions in the solution through the ion exchange membrane. It is a physical and chemical process that uses the action of a direct current electric field to cause the directional migration of anions and cations in the solution (that is, the cationic membrane only allows cations to pass through, and the anionic membrane only allows anions to pass through), thereby achieving the separation of ions from the solution. However, the resin needs to be regenerated with alkali solution during use, which inevitably produces waste alkali solution, which increases the difficulty of wastewater treatment. To this end, the present application provides a solution. Summary of the invention

[0005] The present application provides a refining desulfurization amine liquid system, which aims to reduce the amount of wastewater generated, reduce MDEA (methyldiethanolamine) entrainment loss, and reduce regeneration energy consumption through electrodialysis technology; at the same time, it can reduce the waste alkali liquid caused by electrodialysis, reduce production costs, and stabilize the quality of downstream products.

[0006] The present application provides a refining and chemical desulfurization amine liquid purification system, including a pretreatment system, an electrodialysis system and other supporting electromechanical control systems and valve piping systems; the pretreatment system includes a solid separation device, an activated carbon mixing tank, an activated carbon filter and a precision filter connected in sequence; a circulation pump is arranged between the activated carbon mixing tank and the activated carbon filter; the electrodialysis system includes a membrane stack and a fresh water device, an extreme water device, a water production device and a concentrated water device connected to the membrane stack; the membrane stack includes an anode plate, a membrane stack, a cathode plate and a fixed plate for fixing the membrane stack; the membrane stack includes an ion exchange membrane and a partition, the ion exchange membrane includes a cation exchange membrane and an anion exchange membrane alternately arranged with the cation exchange membrane; the exchange membranes are all composed of a base membrane modified with a specific group and anions and cations that move freely on the specific group; the main components of the raw materials of the base membrane include PET (polyethylene terephthalate) and GOM (graphene oxide).

[0007] By adopting the above technical scheme, the present application adopts spin coating of different numbers of layers of GOM on the PET nanochannel to obtain GOM / PET nanochannels with different thicknesses of GOM; wherein, GOM has the function of promoting ion transport, and provides a capillary network on the PET membrane through graphene stone, allowing ions to flow almost frictionlessly between GOM layers, thereby realizing ultrafast ion transport in GOM, reducing the enrichment and depletion of ions in the nanochannel, and thus helping to reduce the blockage of the electrodialysis module membrane stack, reduce the energy consumption and agent consumption of the desulfurization system, and reduce the increase in desulfurization costs.

[0008] Preferably, the amine solution filtered by the pretreatment system enters the membrane stack through the desalination device, and enters the water production device after removing part of the heat-stable salt from the membrane stack, and is sent out through the water production device; the concentrated water device circulates with the membrane stack to carry out the heat-stable salt; the polar water device adjusts the ion concentration of the membrane stack; the cation Na in the desalination device + , Ca 2+ Mg 2+ , Fe 2+ , Fe 3+ , K + 、Al 3+ Through the cation exchange membrane, HS - , Cl - 、SO4 2- 、SO3 - HCOO - 、C2O4 2- 、C2H3O3 - 、C3H2O4 2- 、C2H3O 2- 、C4H4O4 2- 、S2O32- 、SCN - Through the anion exchange membrane; the anions and cations in the fresh water device are transferred to the concentrated water device, and the above-mentioned heat-stable salt is taken out in the circulation.

[0009] Preferably, the base film is based on the PET (polyethylene terephthalate) film by preparing nanochannels on the PET film using asymmetric chemical etching.

[0010] By adopting the above technical scheme, in biological or artificial nanochannels, the nonlinear current potential (IV) curve caused by asymmetric ion migration is called ion current rectification (ICR). Since ICR usually occurs in nanochannels with asymmetric structure and surface charge distribution, or asymmetric electrolyte concentrations at both ends of the nanochannel. The present application uses asymmetric chemical etching to open a nanochannel on a PET film; constructs an "ion pool" with different ion concentrations on both sides, and stimulates the rapid movement of ions on both sides under the action of current, thereby reducing the blockage of the electrodialysis module membrane stack. In addition, due to the provision of precise layered nanochannels, the ICR effect can effectively prevent ion backflow, thereby avoiding energy dissipation when the membrane transfers energy to the external load, thereby improving energy conversion efficiency and reducing the increase in desulfurization costs.

[0011] Preferably, negatively charged GOM is distributed on the anion exchange membrane based on the nanochannel.

[0012] The surface charge density of the GOM (graphene oxide) is set to -0.05~-0.15C / m 2 .

[0013] Preferably, the mass ratios of the anion exchange membrane based on the GOM (graphene oxide) and the PET (polyethylene terephthalate) are 1:1, 1:2, 1:5, and 1:10, respectively; and the following corresponding models are prepared: GOM / PET, GOM / 2-PET, GOM / 5-PET, and GOM / 10-PET.

[0014] Preferably, the cation exchange membrane has p-GOM with positive charge distributed on the nanochannel; and the p-GOM is surface-positively modified by the GOM.

[0015] Preferably, the surface charge density of the p-GOM (graphene oxide) is set to 0.05-0.15 C / m 2 .

[0016] Preferably, the mass ratios of the cation exchange membrane based on the PET (polyethylene terephthalate) and the p-GOM (graphene oxide) are 1:1, 1:2, 1:5, and 1:10, respectively; and the following corresponding models are prepared: p-GOM / PET, p-GOM / 2-PET, p-GOM / 5-PET, and p-GOM / 10-PET.

[0017] One or more technical solutions provided in this application have at least the following technical effects or advantages: 1. The present application adopts GOM with different numbers of layers spin-coated on PET nanochannels to obtain GOM / PET nanochannels with different thicknesses of GOM; wherein, GOM has the function of promoting ion transport, and provides a capillary network on the PET membrane through graphene stone, allowing ions to flow almost frictionlessly between GOM layers, thereby realizing ultrafast ion transport in GOM, reducing the enrichment and depletion of ions in the nanochannel, and thus helping to reduce the blockage of the electrodialysis module membrane stack, reduce the energy consumption and agent consumption of the desulfurization system, and reduce the increase in desulfurization costs.

[0018] 2. This application uses asymmetric chemical etching to open nanochannels on the PET film; constructs an "ion pool" with different ion concentrations on both sides, and stimulates the rapid movement of ions on both sides under the action of current, thereby reducing the blockage of the electrodialysis module membrane stack. In addition, due to the precise layered nanochannels, the ICR effect can effectively prevent ion backflow, thereby avoiding energy dissipation when the membrane transfers energy to the external load, thereby improving energy conversion efficiency and reducing the increase in desulfurization costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is a flow chart of the refining and desulfurization amine liquid system in the embodiment of this application; Figure 2 This is a schematic diagram of a membrane stack in an embodiment of the present application; Figure 3 This is a flow chart of refining desulfurization amine liquid in the embodiment of this application; Figure 4 This is a comparison chart of the transparency of the amine solution before and after filtration in the embodiment of this application. DETAILED DESCRIPTION

[0021] The present application provides a refining desulfurization amine liquid system, which aims to reduce the amount of wastewater generated, reduce MDEA (methyldiethanolamine) entrainment loss, and reduce regeneration energy consumption through electrodialysis technology; at the same time, it can reduce the waste alkali liquid caused by electrodialysis, reduce production costs, and stabilize the quality of downstream products.

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0023] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or server that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products, or devices.

[0024] Raw material example Preparation of PET base film: S1. First, a scintillator detector is installed on the back of the PET film to monitor the number of ions; and the film is placed at room temperature for irradiation for 3 hours, with an initial kinetic energy of 2.1 GeV. S2, exposing the upper and lower surfaces of the PET film to 36 nm ultraviolet light for 1 h respectively to sensitize the radiation damaged area; S3. At 50-60°C, install the irradiated PET film between the electrochemical tanks, add 8M NaOH etching solution to one tank, and add a neutralizing solution of 1M KCl and 1M HCOOH mixed in a ratio of 1:1 to the other tank; S4. Immerse the two Pt electrodes in etching solution and neutralizing solution respectively, apply a bias of 100 mV at the same time, and use a picoammeter to record the transmembrane current. When the transmembrane current increases from 0.01 nA to 1 nA, stop the chemical etching and rinse the PET film with deionized water several times to remove the residual chemicals.

[0025] Preparation of GMO S1. Dissolve 1.5 kg of graphite powder in a mixed acid solution consisting of 1.8 L of concentrated sulfuric acid and 0.2 L of phosphoric acid at 5 °C, and place in a constant temperature reactor and stir for 3 h; S2, weigh 3 kg of potassium permanganate and slowly add it into the mixed solution, then raise the reaction temperature to 50°C and react for 12 hours; S3, the solution was cooled to room temperature, 2L of deionized water was frozen into ice cubes and then 0.1L of hydrogen peroxide was added, and the obtained product was washed with 1M hydrochloric acid and 50% ethanol for 3 times respectively; S3. Continuously centrifuge and wash with deionized water until the product is nearly neutral; finally, the obtained product is dispersed in deionized water and ultrasonically treated to prepare a standard graphene oxide solution for use.

[0026] Preparation of p-GMO S1. Take 1.5L of the above standard graphene, add 1kg of EDC into the solution and stir for 1h; S2. Add 0.5 kg of polyethyleneimine (PEI) to the mixed solution, stir for 3 h, inject the stirred solution into a dialysis bag, and dialyze in deionized water for 48 h to obtain a p-GMO solution.

[0027] Example 1

[0028] Reference Figure 1 The present application provides a refining desulfurization amine liquid system, including a pretreatment system, an electrodialysis system and other supporting electromechanical control systems and valve pipeline systems; wherein the pretreatment system includes a solid separation device, an activated carbon mixing tank, an activated carbon filter and a precision filter connected in sequence; a circulation pump is provided between the activated carbon mixing tank and the activated carbon filter; The electrodialysis system includes a membrane stack and a fresh water device, an electrode water device, a water production device and a concentrated water device connected to the membrane stack; the membrane stack includes an anode plate, a membrane stack, a cathode plate and a fixed plate for fixing the membrane stack.

[0029] Specifically, refer to Figure 1 The fresh water device includes a fresh water tank and a fresh water pump. The fresh water pump is used to transport the lean liquid that has been filtered in the pretreatment system from the fresh water tank to the membrane stack. The polar water device includes a polar water tank and a polar water pump. The polar water tank is equipped with salt water to provide ionic liquid for the plates of the membrane stack to enhance the conductivity of the plates. The polar water is transported to the membrane stack for circulation through the polar water pump. The water production device includes a water production pump and a water production tank. The lean liquid enters the water production tank after passing through the membrane stack to remove part of the heat-stable salt, and is sent out of the device through the water production pump. The concentrated water device includes a concentrated water tank and a concentrated water pump. The concentrated water pump is used to form a circulation between the concentrated water tank and the membrane stack, and the heat-stable salt is taken out of the membrane stack through uninterrupted salt water.

[0030] Furthermore, the membrane stack includes an ion exchange membrane and a partition, and the ion exchange membrane includes a cation exchange membrane and an anion exchange membrane alternately arranged with the cation exchange membrane. The electrodialysis membrane stack is the core component of the solvent regeneration device. Figure 2 When the lean solution passes through the electrodialysis compartment formed by alternately stacking anion and cation exchange membranes and concentrated and fresh water partitions with electrodes at both ends, ion directional migration occurs under the action of the DC electric field, that is, cations migrate toward the cathode direction, and anions migrate toward the anode direction. Since the ion exchange membrane has selective permeability, the anion exchange membrane can only allow anions to pass through, and the cation exchange membrane can only allow cations to pass through. As a result, the anions in the fresh water chamber migrate toward the anode direction and pass through the anion membrane into the concentrated water chamber, and the cations migrate toward the cathode direction and pass through the cation membrane into the concentrated water chamber; and the anions and cations in the concentrated water chamber, although they also migrate toward the anode and cathode directions respectively under the action of the DC electric field, are blocked by the cation membrane and anion membrane on both sides of the compartment and cannot migrate out of the concentrated water chamber, so they remain in the concentrated water chamber. In this way, the concentration of the concentrated water chamber increases due to the continuous entry of anions and cations, and the concentration of the fresh water chamber decreases due to the continuous removal of anions and cations. Through the special holes on the edge of the partition, the water flows of each concentrated and fresh water compartments are respectively gathered and led out, thus generating two main water flows, the purified solvent and the concentrated liquid.

[0031] ‌For further information, see Figure 3 The electrodialysis system in this application is integrated inside the container to form a movable skid-mounted solvent regeneration device. Each sub-equipment is arranged on both sides of the container, and a maintenance operation channel is laid in the middle.

[0032] Among them, the amine liquid outside the device enters the amine liquid tank after multiple filtration and heat exchangers, and is then transported to the fresh water chamber of the electrodialysis membrane stack by a fresh water pump. The desalinated amine liquid enters the amine liquid production water tank, and is then transported back to the amine liquid storage tank by an amine liquid production water pump. In this process, the desalination treatment of the amine liquid is continuous, and the PLC control system fine-tunes the regulating valve of the amine liquid inlet and the operating frequency of the water production pump to maintain the stability of the inlet and outlet flow.

[0033] Another operation mode is intermittent operation, that is, after the amine liquid enters the amine liquid tank, the desalinated amine liquid does not enter the amine liquid production water tank, but returns to the amine liquid tank for cyclic desalination treatment. Then, the conductivity value of the effluent from the fresh water chamber of the membrane stack is used to determine whether the discharge standard is met. After the discharge standard is met, the effluent from the fresh water chamber of the membrane stack is discharged to the amine liquid production water tank, and then transported back to the amine liquid storage tank through the amine liquid production water pump. The intermittent operation mode is mainly used for equipment commissioning and testing.

[0034] The concentrate tank is initially filled with desalted water, which is then pumped to the concentrate chamber of the electrodialysis membrane stack by the concentrate pump. It receives the thermally stable salt ions from the amine solution and becomes saline wastewater, which then returns to the concentrate tank and is then pumped to the saline wastewater network by the concentrate / electrode water effluent pump. The saline wastewater is discharged intermittently, and the conductivity of the membrane stack concentrate outlet and the liquid level of the concentrate tank control the start and stop of the concentrate / electrode water effluent pump.

[0035] Initially, desalted water is introduced into the pole water tank and an appropriate amount of sodium chloride solid is added to dissolve evenly to prepare a 1% sodium chloride aqueous solution (this is the pole liquid), which is transported to the cathode and anode chambers of the electrodialysis membrane stack respectively through the pole water pump and then returned to the pole water tank.

[0036] In addition, this application involves three types of filters, among which the first-stage filter is a pleated filter element filter, which is filled with two pleated filter elements with a filtration accuracy of 5μm, and is used to remove larger impurity particles in the lean solvent; the second-stage filter is an activated carbon filter element filter, which is filled with 12 activated carbon filter elements with a filtration accuracy of 1μm; the third-stage filter is a bag filter, which is filled with a filter bag element with a filtration accuracy of 0.5μm. In addition, in order to prevent impurity particles in storage tanks and pipelines from entering the electrodialysis membrane stack and causing blockage, safety filters (post-filters) are installed at the outlets of the fresh water pump, concentrated water pump, and extreme water pump, respectively, and are filled with three filter bag elements with a filtration accuracy of 5μm; in addition, in order to prevent high temperature from damaging the electrodialysis membrane stack, a 12m 2 Plate heat exchanger, set 6m on the salty wastewater pipeline 2 Plate heat exchanger, set 2m on the extreme water pipeline 2 The plate heat exchanger has circulating cooling water on its cold side to cool the above materials.

[0037] This solvent regeneration device adopts an automatic operation mode. The system is controlled by PLC, and the device is started, stopped, debugged and parameter settings are performed through the human-machine interface. The PLC cabinet, membrane stack cabinet and membrane stack power cabinet are all positive pressure explosion-proof cabinets, and the power cabinet is a flameproof cabinet. The PLC cabinet panel is equipped with a human-machine interface, touch screen, start button, stop button, call button, emergency stop button, and power indicator light.

[0038] Differential pressure transmitters, temperature transmitters, liquid level gauges, liquid level switches, conductivity meters, flow meters and other sensors are installed on the system pipelines to monitor the operating status of the device in real time. When a fault occurs, an alarm is issued in time to shut down the device and avoid damage to the electrodialysis membrane stack, pump and other equipment.

[0039] In Example 1 of the present application, the inlet flow rate of the amine solution and the concentrated water is controlled at 8-10m 3 / h, the polar water inlet flow rate is controlled at 2m 3 / h; the temperature of the amine solution entering the membrane stack needs to be controlled at 5-40°C, the long-term operating temperature should not be higher than 35°C, the pH needs to be controlled at 0-11, and the pressure entering the membrane stack needs to be controlled at 0.03-0.1MPa; The temperature of the concentrate entering the membrane stack needs to be controlled at 5-40°C, the long-term operating temperature should not be higher than 35°C, the pH needs to be controlled at 0-11, the pressure entering the membrane stack needs to be controlled at 0.03-0.1MPa, and the conductivity of the concentrate should not exceed 60mS / cm during normal operation; The temperature of the polar water entering the membrane stack needs to be controlled at 5-40℃, the long-term operating temperature should not be higher than 35℃, the pH needs to be controlled at 0-11, the pressure entering the membrane stack needs to be controlled at 0.03-0.1MPa, the polar water is prepared as a sodium chloride solution of about 1%, sodium chloride is required for preparation, and the polar water replacement cycle is 30-45 days. + , Ca 2+ Mg 2+ , Fe 2+ , Fe 3 + , K + 、Al 3+ Through the cation exchange membrane, HS - , Cl - 、SO4 2- 、SO3 - HCOO - 、C2O4 2- 、C2H3O3 - 、C3H2O4 2- 、C2H3O 2- 、C4H4O4 2- 、S2O3 2- 、SCN - Through the anion exchange membrane, the anions and cations in the fresh water device are transferred to the concentrated water device, and the above-mentioned heat-stable salts are taken out during the circulation.

[0040] Among them, the base membranes based on the cation exchange membrane and the anion exchange membrane are both based on PET (polyethylene terephthalate) membranes and nanochannels are prepared on the PET membrane by asymmetric chemical etching. In biological or artificial nanochannels, the nonlinear current potential (IV) curve caused by asymmetric ion migration is called ion current rectification (ICR). Since ICR usually occurs in nanochannels with asymmetric structure and surface charge distribution, or asymmetric electrolyte concentrations at both ends of the nanochannel. The present application opens a nanochannel by asymmetric chemical etching on the PET membrane; constructs an "ion pool" with different ion concentrations on both sides, and stimulates the rapid movement of ions on both sides under the action of current, thereby reducing the blockage of the electrodialysis module membrane stack. In addition, due to the setting of precise layered nanochannels, the ICR effect can effectively prevent ion backflow, thereby avoiding energy dissipation when the membrane transfers energy to the external load, thereby improving energy conversion efficiency and reducing the increase in desulfurization costs.

[0041] The selectivity of the nanochannel results in different ion currents for the common ion (the ion has the same electrical properties as the nanochannel) and the counter ion. Based on the ICR effect, ion backflow can be effectively prevented. The Gibbs free energy loss dG during the migration of ions from the high concentration side (CH) to the low concentration side (CL) is (taking monovalent ions as an example), and the Gibbs free energy loss dG is obtained:

[0042] By the definition of chemical potential, we get:

[0043] In order to maintain the concentration of the solution on both sides of the membrane, it can be reversed and the Gibbs free energy on both sides is:

[0044] Since the electric field strength increases with the increase of GOM surface charge density under positive and negative voltages, this indicates that the depletion and enrichment in the nanochannel under positive and negative voltages will also increase with the increase of GOM surface charge density. Since the concentration increases due to ion enrichment, the thickness of EDL (double electric layer at the substrate-solution interface) is further reduced, and ions can enter the nanochannel more easily, further increasing the current under negative bias. As the ion concentration (Cn+Cp) in the nanochannel gradually increases, and under positive bias, the ion concentration (Cn+Cp) in the nanochannel gradually decreases, the enrichment and depletion of ions in the nanochannel are reduced, which helps to reduce the blockage of the electrodialysis module membrane stack.

[0045] Furthermore, the nanochannel pore size on the PET (polyethylene terephthalate) membrane in the present application is 10-100 nm; and the total thickness of the GOM is set to 10-20 nm, which promotes the cationic Na + , Ca 2+ Mg 2+ , Fe 2+ , Fe 3+ , K + 、Al 3+ Through the cation exchange membrane, HS - , Cl - 、SO4 2- 、SO3 - HCOO - 、C2O4 2- 、C2H3O3 - 、C3H2O4 2- 、C2H3O 2- 、C4H4O4 2- 、S2O3 2- 、SCN - through anion exchange membrane.

[0046] Specifically, in the present application, negatively charged GOM is distributed on the anion exchange membrane based on the nanochannels. And the surface charge density of GOM (graphene oxide) is set to -0.05~-0.15C / m 2 .

[0047] The anion exchange membrane in the present application is based on GOM (graphene oxide) and PET (polyethylene terephthalate) in a mass ratio of 1:1. GOM (graphene oxide) is spin-coated on PET (polyethylene terephthalate) to prepare an anion exchange membrane of model GOM / PET.

[0048] In the other part, the positively charged p-GOM is distributed on the nanochannels of the cation exchange membrane; the p-GOM is surface-positively modified by GOM. In addition, the surface charge density of p-GOM (graphene oxide) is set to 0.05~0.15C / m 2 .

[0049] The cation exchange membrane in this application is based on p-GOM (graphene oxide) and PET (polyethylene terephthalate) in a mass ratio of 1:1, and an anion exchange membrane of model p-GOM / PET is prepared. Before spin coating GOM (graphene oxide) on the PET film, the PET film is treated in an oxygen plasma environment for 10 minutes to enhance the surface hydrophilicity of the PET film and make GOM and PET more closely combined.

[0050] The present application also prepares GOM / 2-PET, GOM / 5-PET, and GOM / 10-PET based on anion exchange membrane GOM (graphene oxide) and PET (polyethylene terephthalate) in mass ratios of 1:2, 1:5, and 1:10, respectively.

[0051] In addition, p-GOM (graphene oxide) and PET (polyethylene terephthalate) were prepared in mass ratios of 1:2, 1:5, and 1:10 to obtain p-GOM / 2-PET, p-GOM / 5-PET, and p-GOM / 10-PET, respectively.

[0052] Embodiment 2-6 The difference between Example 2-6 and Example 1 is that the selection of anion exchange membrane and cation exchange membrane is different, and the different combinations are organized into a table as follows: Table 1. Summary of ion exchange membranes of Examples 1-6

[0053] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that a cation exchange membrane (CEM) is used, which contains negatively charged functional groups and can selectively allow positively charged ions (cations) to pass through. In Comparative Example 1, the cation exchange membrane used in the comparative example of the present application is a COM amine liquid cation membrane with an ion exchange capacity of 1.5-2 mol / kg and a membrane surface resistance of 2-3 Ω.cm. 2 ; Anion exchange membrane (AEM) contains positively charged functional groups, which can selectively allow negatively charged ions (anions) to pass through while blocking cations. The anion exchange membrane used in the comparative example of this application is AOM amine liquid anion membrane, with an ion exchange capacity of 1.5-2 mol / kg; membrane surface resistance of 2-3Ω.cm 2 .

[0054] According to Examples 1-6 and Comparative Example 1, the present application conducted a control experiment based on a batch of amine solutions with a thermal steady-state salt concentration of 8.95% and a suspended solids (>1 μm) content of 368 mg / L, wherein the appearance was reddish brown and turbid, and the Figure 4 The left picture shows that the concentration of sodium ions in a group of anions and cations was 9655ppm, and the concentration of chloride ions was 8152ppm. The samples were passed through different anion exchange membranes and cation exchange membranes to obtain the following data table.

[0055] Table 2, test table of Examples 1-6 and Comparative Example 1

[0056] According to the current detection standards, the thermally stable salt after amine solution purification is ≤1.5%, and the solid particles larger than 1μm in the amine solution are less than or equal to 150ppm; the chloride ion content is ≤500ppm, and the sodium ion content is ≤1000ppm; the amine solution has a clear appearance, and there is no precipitation, no stratification, no oil particles, etc. after standing for a long time, which meets the technical agreement indicators. In Examples 1-6 of the present application and Comparative Example 1, all meet the detection standards, wherein the anion exchange membrane and the cation exchange membrane of Example 1 and Example 6 are different from each other in that asymmetric chemical etching is used to prepare nanochannels on the PET film. Under the action of the same current, the ions on both sides are stimulated to move rapidly, thereby reducing the blockage of the membrane stack of the electrodialysis module. Avoid energy dissipation when the membrane transfers energy to the external load, thereby improving the energy conversion efficiency and reducing the increase in desulfurization costs. In Example 2, the anion exchange membrane used is GOM / 2-PET; the cation exchange membrane is p-GOM / 2-PET; when the concentration of the thermally stable salt before purification is 8.95%, it reaches 1.18% after purification, which not only meets the standard, but also is lower than other embodiments. At the same time, after purification, the content of suspended solids (>1μm) was reduced from 368 mg / L to 31.3 mg / L; and its appearance can be seen from Figure 4 It can be seen that the purified amine solution changes from reddish brown turbidity to light brown clarity. In addition, the concentration of sodium ions after purification is reduced from 9655ppm to 808ppm, and the concentration of chloride ions is reduced from 8152ppm to 415ppm. After the above analysis, it can be concluded that Example 2 is the best example.

[0057] It should be noted that the above-mentioned sequence of the embodiments of the present application is only for description and does not represent the advantages and disadvantages of the embodiments. And the above-mentioned specific embodiments of this specification are described. Other embodiments are within the scope of the attached claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0058] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

[0059] This specification and drawings are merely exemplary illustrations of the present application and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of the present application. Obviously, a person skilled in the art may make various modifications and variations to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the present application and its equivalents, the present application intends to include these modifications and variations.

Claims

1. A refinery desulfurization amine liquid purification system, characterized in that: Including pretreatment system, electrodialysis system and other supporting electromechanical control systems and valve piping systems; The pretreatment system comprises a solid separation device, an activated carbon mixing tank, an activated carbon filter and a precision filter connected in sequence; a circulation pump is arranged between the activated carbon mixing tank and the activated carbon filter; The electrodialysis system comprises a membrane stack and a fresh water device, an electrode water device, a water production device and a concentrated water device connected to the membrane stack; the membrane stack comprises an anode plate, a membrane stack, a cathode plate and a fixed plate for fixing the membrane stack; The membrane stack includes an ion exchange membrane and a partition, wherein the ion exchange membrane includes a cation exchange membrane and an anion exchange membrane alternately arranged with the cation exchange membrane; the exchange membranes are composed of a base membrane modified with specific groups and anions and cations that move freely on the specific groups; the raw materials of the base membrane mainly include PET (polyethylene terephthalate) and GOM (graphene oxide).

2. The refining desulfurization amine liquid purification system according to claim 1, characterized in that: The amine solution filtered by the pretreatment system enters the membrane stack through the desalination device, and enters the water production device after removing part of the heat-stable salt from the membrane stack, and is sent out through the water production device; the concentrated water device circulates with the membrane stack to carry out the heat-stable salt; the polar water device adjusts the ion concentration of the membrane stack; The cation Na in the desalination device + , Ca 2+ Mg 2+ , Fe 2+ , Fe 3+ , K + 、Al 3+ Through the cation exchange membrane, HS - , Cl - 、SO4 2- 、SO3 - HCOO - 、C2O4 2- 、C2H3O3 - 、C3H2O4 2- 、C2H3O 2- 、C4H4O4 2- 、S2O3 2- 、SCN - Through the anion exchange membrane; the anions and cations in the fresh water device are transferred to the concentrated water device, and the above-mentioned heat-stable salt is taken out in the circulation.

3. The refining desulfurization amine liquid purification system according to claim 2, characterized in that: The base film is based on the PET (polyethylene terephthalate) film and nanochannels are prepared on the PET film by asymmetric chemical etching.

4. The refining desulfurization amine liquid purification system according to claim 3, characterized in that: The anion exchange membrane has negatively charged GOM distributed on the nanochannel.

5. The refining desulfurization amine liquid purification system according to claim 4, characterized in that: The surface charge density of the GOM (graphene oxide) is set to -0.05~-0.15C / m 2 .

6. The refinery desulfurization amine liquid purification system according to claim 5, characterized in that: The mass ratios of the anion exchange membrane based on the GOM (graphene oxide) and the PET (polyethylene terephthalate) are 1:1, 1:2, 1:5, and 1:10, respectively; and the following corresponding models are prepared: GOM / PET, GOM / 2-PET, GOM / 5-PET, and GOM / 10-PET.

7. The refinery desulfurization amine liquid purification system according to claim 3, characterized in that: The cation exchange membrane is provided with positively charged p-GOM distributed on the nanochannel; the surface of the p-GOM is positively modified by the GOM.

8. The refinery desulfurization amine liquid purification system according to claim 7, characterized in that: The surface charge density of the p-GOM (graphene oxide) is set to 0.05~0.15C / m 2 .

9. The refinery desulfurization amine liquid purification system according to claim 8, characterized in that: The mass ratios of the cation exchange membrane based on the PET (polyethylene terephthalate) and the p-GOM (graphene oxide) are 1:1, 1:2, 1:5, and 1:10 respectively; The following models are prepared: p-GOM / PET, p-GOM / 2-PET, p-GOM / 5-PET, and p-GOM / 10-PET.

10. The refinery desulfurization amine liquid purification system according to claim 3, characterized in that: The pore size of the nanochannel on the PET (polyethylene terephthalate) membrane is 10-100 nm; the total thickness of the GOM is set to 10-20 nm.

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