System and method capable of realizing zero emission of amine-containing wastewater and heat recovery of carbon capture system

Abstract

The invention relates to the technical field of carbon capture, and discloses a system and a method capable of realizing zero emission of amine-containing wastewater and heat recovery of a carbon capture system. The system comprises a wastewater generation unit, a wastewater circulation concentration unit, an amine-containing steam heat / amine recovery unit, a high-salinity concentrated water flue evaporation unit, a high-salinity concentrated water desalination unit, a wastewater concentration monitoring system, a heat recovery coupling system, a water balance regulation and control system and a terminal intelligent control system. According to the amine-containing wastewater zero discharge and heat recovery system and method for the carbon capture system, low-cost amine-containing wastewater zero discharge treatment and energy conservation and consumption reduction of the coupled carbon capture system are successfully achieved, and the problems that an existing carbon capture system is not ideal in amine-containing wastewater recovery effect and high in treatment cost are solved; the method has important significance in the industry.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon capture, and in particular to a system and method capable of achieving zero discharge of amine-containing wastewater and heat recovery in a carbon capture system. Background Art

[0002] Carbon capture technology refers to a range of methods that aim to capture carbon dioxide from industrial and energy production processes and transport it to storage sites for long-term isolation or convert it into useful products. This technology is considered one of the important strategies to reduce greenhouse gas emissions and combat climate change.

[0003] At present, chemical absorption is the most mature and commercially valuable carbon capture technology. Studies have found that the heat-stable salts (HSS) produced by the degradation of organic amine absorbents (amine liquid for short) during use will have an adverse effect on the carbon capture system. Engineering applications usually use ion purification processes to remove HSS in amine liquids to improve the performance of carbon capture systems. However, due to the characteristics of the purification process, amine-containing wastewater will be produced during the amine liquid purification process. The total amount of this wastewater is not only large, but also the composition is complex, and it does not meet the water quality requirements for direct discharge. The use of existing technologies to treat amine-containing wastewater at the site of carbon capture projects has the problems of overall difficulty and high cost, which can easily lead to a decline in the economic benefits of carbon capture projects. Therefore, in the context of increasingly stringent environmental protection requirements, it is particularly important to achieve a low-cost zero-discharge treatment method for amine-containing wastewater; at the same time, coupling energy-saving processes in the treatment process of amine-containing wastewater to reduce the consumption of external heat sources by the carbon capture system has a decisive impact on the promotion of chemical absorption carbon capture technology.

[0004] At present, there is no reported effective treatment solution for amine-containing wastewater in carbon capture systems. Generally, acid is added to amine-containing wastewater for neutralization reaction, and the wastewater is converted into a neutral saline wastewater for treatment. In this process, organic amines react with acids, resulting in the inability to recover organic amines in the wastewater, increasing the loss of organic amines. The treatment methods for saline wastewater mainly include evaporation crystallization, membrane concentration and other water treatment technologies. Among them, the evaporation crystallization process uses the difference in liquid boiling points to achieve zero discharge of wastewater, and the crystallized salt at the end of the process is then disposed of as solid waste; however, this process usually uses steam as a heat source, which consumes a lot of energy and is expensive, resulting in an increase in the cost of treating amine-containing wastewater. Membrane concentration technology has certain advantages in treating wastewater with high salt content and large scale, but membrane concentration can only achieve wastewater reduction, and the concentrated wastewater still faces the problem of zero discharge disposal. At the same time, the process has problems such as complex process and high investment in membrane components.

[0005] Therefore, the current treatment methods cannot fundamentally solve the problem of amine-containing wastewater treatment, and the high treatment costs will also cause a significant increase in the operating costs of the carbon capture system. Summary of the invention

[0006] The present invention aims to provide a system and method for achieving zero discharge and heat recovery of amine-containing wastewater in a carbon capture system, so as to solve the problems of unsatisfactory recovery effect and high treatment cost of amine-containing wastewater in a carbon capture system in the prior art.

[0007] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a system that can achieve zero discharge and heat recovery of amine-containing wastewater in a carbon capture system, including a wastewater generation unit, a wastewater circulation concentration unit, an amine-containing steam heat / amine recovery unit, a high-salt concentrated water flue evaporation unit, a high-salt concentrated water desalination unit, a wastewater concentration monitoring system, a heat recovery coupling system, a water balance control system, and a terminal intelligent control system.

[0008] Preferably, as an improvement, the wastewater circulation and concentration unit includes a wastewater circulation box, a waste heat exchanger, a wastewater flash tank, a wastewater delivery pump, and a concentrated water circulation pump, and the heat source of the wastewater circulation and concentration unit is high-temperature flue gas.

[0009] In this technical solution, an induced draft fan is used to extract high-temperature flue gas from the main flue, and heat is exchanged with amine-containing wastewater in the waste heat exchanger, and then returned to the main flue after the heat exchange is completed. The amine-containing wastewater is pumped into the waste heat exchanger through the wastewater delivery pump in the wastewater circulation box, and enters the wastewater flash tank after heating. The wastewater flash tank is a negative pressure environment, and the high-temperature amine-containing wastewater flashes in the tank. The generated water vapor carries organic amines, and the salt remains in the concentrated water, achieving wastewater concentration and reduction. If the concentration rate does not meet the design requirements, the concentrated water circulation pump is used to pump the concentrated water into the wastewater circulation box.

[0010] Preferably, as an improvement, the amine-containing steam heat / amine recovery unit comprises an amine-containing steam compressor, an energy level control unit, a small-stream rich liquid heat exchanger, and a condensate cooler.

[0011] In this technical solution, the amine-containing wastewater is evaporated in the wastewater flash tank, and the amine-containing steam is generated and enters the amine-containing steam compressor. Under the control of the energy level control unit, the temperature and pressure are increased to a high enthalpy steam heat source. Subsequently, the amine-containing steam exchanges heat with a small portion of rich liquid in a small portion of rich liquid heat exchanger. After the heat exchange is completed, the amine-containing steam is condensed, and the condensate is further cooled by the condensate cooler. After reaching the inlet temperature requirement of the carbon capture system, it is passed into the absorption tower to achieve amine recovery of the amine-containing wastewater. At the same time, the small portion of rich liquid is heated after heat exchange to complete heat recovery, effectively reducing the steam consumption of the regeneration tower and reducing the regeneration heat consumption of the carbon capture system.

[0012] Preferably, as an improvement, the high-salt concentrated water flue evaporation unit includes a high-salt concentrated water outlet pump, a flue direct injection regulating valve, and a single-phase atomizing spray gun.

[0013] In this technical solution, the flue direct injection regulating valve is opened, and high-salt concentrated water is pumped into the single-phase atomizing spray gun through the high-pressure concentrated water outlet pump. After efficient atomization, it is sprayed into the main flue. The heat of the high-temperature flue gas in the flue is used to completely evaporate the high-salt concentrated water. The generated water vapor is mixed into the flue gas, and the salts in the concentrated water are precipitated and intercepted by the rear-end dust collector, achieving zero discharge of amine-containing wastewater.

[0014] Preferably, as an improvement, the high-salt concentrated water desalination unit includes a high-salt concentrated water outlet pump, a crystallization regulating valve, and a salting-out crystallizer.

[0015] In this technical solution, the crystallization regulating valve is opened, and the high-salt concentrate water is pumped into the salting-out crystallizer through the high-pressure concentrate water outlet pump. The temperature difference is used to realize the crystallization of salts in the high-salt concentrate water. The remaining concentrate water is returned to the wastewater circulation tank, and the crystallized salt is disposed of as solid waste. This treatment method can completely eliminate the risk of amine-containing wastewater discharge.

[0016] Preferably, as an improvement, the wastewater concentration monitoring system includes a 1# TDS detector, a concentrated water circulation pump, a wastewater regulating valve, and a flue regulating valve.

[0017] In this technical solution, a 1#TDS detector is arranged at the bottom of the wastewater flash tank, which can monitor the dissolved salt content in the concentrated water in real time and serve as a basis for judging the wastewater concentration rate. The data of the 1#TDS detector is used as the system logic control point. If the dissolved salt content of the concentrated water in the wastewater flash tank is lower than the design range (30,000-45,000 mg / L), the concentrated water circulation pump is started to circulate and concentrate the concentrated water in the wastewater flash tank, the wastewater circulation box, and the waste heat exchanger. At the same time, the wastewater regulating valve and the flue gas regulating valve can also be used to control the treatment volume of amine-containing wastewater and the flue gas volume, so as to achieve precise control of the wastewater concentration rate.

[0018] Preferably, as an improvement, the heat recovery coupling system includes an energy level control unit, an inlet temperature sensor, an outlet temperature sensor, and a small-stream rich liquid regulating valve.

[0019] In the present technical solution, the energy level control unit is the control brain of the amine-containing steam compressor. When the inlet steam flow, temperature and pressure of the amine-containing steam compressor fluctuate, the energy level control unit can stably output various levels of steam, and the small-stream rich liquid regulating valve is coupled to control the solution flow, so as to achieve precise control of the outlet temperature of the small-stream rich liquid, thereby ensuring efficient heat recovery and system energy saving.

[0020] Preferably, as an improvement, the water balance control system includes a rich liquid density detector, a condensate cooler, a wastewater regulating valve, and a flue regulating valve.

[0021] In this technical solution, the density of the rich liquid at the outlet of the absorber can accurately reflect the water balance of the carbon capture system. If the monitoring data of the rich liquid density detector deviates from the design range (1.050~1.120mg / cm 3 ), the water balance control system starts to work. By controlling the opening of the wastewater regulating valve and the flue regulating valve, the amount of amine-containing steam generated in the wastewater flash tank is adjusted, and the amount of condensate entering the absorption tower is reduced or increased, so as to achieve effective control of the carbon capture water balance.

[0022] Preferably, as an improvement, the terminal intelligent control system includes a flue direct injection regulating valve, a pressure sensor, a single-phase atomizing spray gun, an atomization particle size monitor, a crystallization regulating valve, and a 2#TDS detector. The atomization effect of high-salt concentrated water is monitored and regulated by the pressure sensor and the atomization particle size monitor, so that the atomization pressure is 1.0-3.0MPa and the atomization particle size is 50-150μm.

[0023] In this technical solution, the atomization effect of high-salt concentrated water through a single-phase atomizing spray gun is obtained through a pressure sensor and an atomization particle size monitor to ensure that the high-salt concentrated water is evaporated within the designed flue length; if the pipeline pressure or atomization particle size deviates from the design range (pressure: 1.0-3.0MPa; atomization particle size: 50-150μm), the flue direct injection regulating valve opening is adjusted to dynamically control the flue to avoid adverse conditions such as flue hardening and blockage. The dissolved salt content of the concentrated water at the outlet of the salting-out crystallizer is monitored by the 2#TDS detector. If the monitored dissolved salt content deviates from the design range (8000-15000mg / L), the cooling water flow is adjusted to obtain different temperature drops of the high-salt concentrated water in order to adjust the single-cycle desalination amount, ensuring that the dissolved salt content of the concentrated water at the outlet of the salting-out crystallizer meets the requirements.

[0024] Preferably, as an improvement, a method for achieving zero discharge and heat recovery of amine-containing wastewater in a carbon capture system comprises the following steps:

[0025] (1) The amine liquid outside the carbon capture absorption tower enters the amine liquid heat-stable salt purification device through a bypass pipeline, and returns to the amine liquid main pipeline after purification and quality improvement; the amine-containing wastewater generated by the purification device enters the wastewater circulation box for circulating concentration treatment;

[0026] (2) High-temperature flue gas is extracted from the main flue and passed into the waste heat exchanger. The flue gas volume is controlled by the flue regulating valve;

[0027] (3) The amine-containing wastewater in the wastewater circulation box is passed into the waste heat exchanger, and the wastewater flow rate is controlled by the wastewater regulating valve;

[0028] (4) The high-temperature flue gas and the amine-containing wastewater exchange heat in the waste heat exchanger. The flue gas returns to the main flue after heat exchange and cooling, and the amine-containing wastewater enters the wastewater flash tank after heat exchange and heating;

[0029] (5) Amine-containing wastewater is evaporated at low temperature under negative pressure in a wastewater flash tank, and the generated amine-containing steam is discharged from the exhaust port at the top of the wastewater flash tank, and the remaining high-salt concentrated water is discharged from the drain port at the bottom of the wastewater flash tank;

[0030] (6) Monitor the dissolved salt content of the concentrated water in real time through the 1# TDS detector. When the dissolved salt content of the concentrated water is lower than 30,000-45,000 mg / L, start the concentrated water circulation pump to circulate and heat the wastewater in the wastewater flash tank, wastewater circulation tank, and waste heat exchanger for concentration; if the dissolved salt content of the concentrated water is within the design range, it enters the zero emission treatment device;

[0031] (7) After entering the amine-containing steam compressor, the amine-containing steam is heated and pressurized to become a steam heat source with a high enthalpy value, and then enters the small-stream rich liquid heat exchanger to exchange heat with the rich liquid;

[0032] (8) When the steam flow, temperature and pressure at the inlet of the amine-containing steam compressor fluctuate, they are regulated by the energy level control unit;

[0033] (9) Start the small-stream rich liquid regulating valve to allow the rich liquid to enter the small-stream rich liquid heat exchanger to exchange heat with the steam heat source. After the rich liquid is heated, it enters the regeneration tower;

[0034] (10) The amine-containing vapor is cooled and condensed after completing heat exchange in the small-stream rich liquid heat exchanger, and is further cooled by the condensate cooler. After reaching the required inlet temperature, it is introduced into the absorption tower;

[0035] (11) The rich liquid density detector monitors the rich liquid density. If the density data deviates from the design range of 1.050 to 1.120 mg / cm 3 , then start the water balance control system;

[0036] (12) Following process (6), the high-salt concentrated water at the bottom of the wastewater flash tank is pumped into a zero-emission treatment device through a high-salt concentrated water outlet pump. The zero-emission treatment device includes a flue direct injection device and a salt precipitation crystallization device;

[0037] When the zero emission treatment is a flue direct injection device, the high-salt concentrated water is atomized by a single-phase atomizing spray gun and then directly sprayed into the main flue before the dust collector. The high-salt concentrated water is completely evaporated by the heat of the high-temperature flue gas in the flue, and the generated water vapor is mixed into the flue gas. The salts in the high-salt concentrated water are precipitated and intercepted by the dust collector, achieving zero wastewater discharge;

[0038] When the zero emission treatment is a salting-out crystallization device, high-salt concentrated water is passed into the salting-out crystallizer, and the temperature difference is used to achieve the crystallization of salts in the high-salt concentrated water. The remaining concentrated water is returned to the wastewater circulation tank for recycling treatment, and the crystallized salt is disposed of as solid waste to achieve zero wastewater emission.

[0039] The principle and beneficial effect of this scheme are: in view of the problems existing in the treatment process of amine-containing wastewater in the carbon capture system in the prior art, the inventor has carried out a comprehensive and integrated technical upgrade of the treatment system and the treatment method: the amine liquid in the carbon capture system is purified to produce amine-containing wastewater, and the wastewater first enters the wastewater circulation box of the wastewater generation unit. In the wastewater circulation concentration unit, the high-temperature flue gas of the main flue is extracted by the induced draft fan, and the amine-containing wastewater is heated by the waste heat exchanger. The wastewater flashes in the negative pressure wastewater flash tank, and the water vapor entrains organic amines to form amine-containing steam, and the salt is retained in the concentrated water to achieve concentration. The amine-containing steam is heated and pressurized by the compressor in the amine-containing steam heat / amine recovery unit to become a high-quality heat source, and heat is exchanged with a small stream of rich liquid. The condensate is returned to the absorption tower to achieve amine recovery, and the small stream of rich liquid is heated to reduce the steam consumption of the regeneration tower. High-salt concentrated water can be sprayed into the main flue through the high-salt concentrated water flue evaporation unit for evaporation, and the salt is intercepted by the dust collector, or enters the high-salt concentrated water desalination unit to crystallize the salt by temperature difference, and the remaining concentrated water is recycled. Each unit works together through the wastewater concentration monitoring system, heat recovery coupling system, water balance control system, and terminal intelligent control system to achieve precise control of the entire process. In this process, the optimization of wastewater concentration rate, heat recovery, and terminal treatment units are the key points of the research and development of this technical solution: the higher the wastewater concentration rate, the higher the organic amine recovery rate, the greater the steam production, and the coupling energy-saving effect with the carbon capture system regeneration tower; for heat recovery, this technical solution uses the energy level control unit to control the steam enthalpy at the outlet of the steam compressor, and after heat exchange with the small amount of rich liquid inhaled by the carbon capture, the purpose of reducing the regeneration heat consumption is achieved; the optimization of the terminal treatment unit (flue spray evaporation or crystallization desalination unit) makes full use of the on-site conditions of the power plant, greatly reduces the difficulty and cost of terminal concentrated water disposal, and achieves zero discharge of amine-containing wastewater.

[0040] The beneficial effects of this technical solution are:

[0041] (1) The wastewater circulation concentration unit provided by the technical solution uses high-temperature flue gas as a heat source and cooperates with negative pressure flash evaporation to achieve heating and concentration of amine-containing wastewater. Compared with the traditional steam concentration process, the technical solution can reduce the steam consumption by about 1.2 tons for treating 1 ton of wastewater, greatly reducing the heat consumption and cost of wastewater concentration. In Example 1, the treatment cost is 72.5 yuan / ton, which is 63.66% lower than the conventional treatment cost of 199.5 yuan / ton; the treatment cost in Example 2 is 84.5 yuan / ton, which is 57.64% lower than the conventional treatment cost.

[0042] (2) The wastewater concentration monitoring system provided by this technical solution adopts the monitoring data of the 1# TDS detector (30,000-45,000 mg / L) as the logical control point of the wastewater concentration rate, and links the wastewater regulating valve and the flue regulating valve to control the treatment volume of amine-containing wastewater and the flue gas volume, which can accurately control the wastewater concentration rate at 70%-90%, thereby achieving efficient wastewater concentration reduction.

[0043] (3) The amine steam heat / amine recovery unit and heat recovery coupling system provided by the present technical solution utilize the steam product of the front-end wastewater concentration unit to precisely control the output of multi-level amine steam with different enthalpy values ​​through the energy level control unit, and couple the small rich liquid regulating valve to precisely control the rich liquid outlet temperature, thereby reducing the heat consumption of the carbon capture system by 3% to 8%.

[0044] (4) The amine-containing steam heat / amine recovery unit provided by the technical solution flashes the amine-containing wastewater in the wastewater flash tank, and the water vapor boils and escapes with a large amount of organic amine, and returns to the carbon capture system after heat exchange and condensation. Since the patent adopts a low-temperature flash process, the organic amine recovery rate is greatly improved to more than 70%.

[0045] (5) The high-salt concentrated water flue evaporation unit provided by this technical solution uses the heat of high-temperature flue gas to evaporate the high-pressure concentrated water after atomization. The precipitated crystallized salt is intercepted by the dust collector, truly achieving zero wastewater discharge. At the same time, the patent strictly controls the flue evaporation processing volume to ensure that the crystallized salt does not affect the ash composition.

[0046] (6) The high-salt concentrated water desalination unit provided by this technical solution utilizes temperature difference changes to achieve crystallization of salts in high-salt concentrated water, transforming wastewater treatment into solid waste treatment, reducing the difficulty of waste treatment and completely eliminating the risk of wastewater discharge.

[0047] (7) The terminal intelligent control system provided by this technical solution monitors and controls the atomization effect of high-salt concentrated water (pressure: 1.0-3.0 MPa; atomization particle size: 50-150 μm) through pressure sensors and atomization particle size monitors to ensure that the concentrated water evaporates within the designed flue length and avoid adverse conditions such as flue hardening and blockage.

[0048] (8) The water balance control system provided by this technical solution, including a rich liquid density detector, a wastewater control valve, a flue control valve, etc., has the characteristics of accurate detection, rapid response, and adequate control, which can effectively avoid fluctuations in the water balance of the carbon capture system. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 The present invention is a structural schematic diagram of a carbon capture system capable of achieving zero discharge of amine-containing wastewater and a heat recovery system.

[0050] Figure 2 This is a schematic diagram of the system structure of Example 1 of the present invention.

[0051] Figure 3 This is a schematic diagram of the system structure of Example 2 of the present invention. DETAILED DESCRIPTION

[0052] The following is further described in detail through specific implementations, but the implementation of the present invention is not limited thereto. Unless otherwise specified, the technical means used in the following implementations are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; the materials, reagents, etc. used can all be obtained from commercial channels.

[0053] The figure marks in the drawings of the specification include: wastewater circulation box 1, wastewater delivery pump 2, wastewater regulating valve 3, waste heat exchanger 4, flue regulating valve 5, induced draft fan 6, water flash tank 7, concentrated water circulation pump, 1#TDS detector 9, high-salt concentrated water outlet pump 10, amine-containing steam compressor 11, energy level control unit 12, small-stream rich liquid heat exchanger 13, condensate cooler 14, rich liquid density detector 15, small-stream rich liquid regulating valve 16, inlet temperature sensor 17, outlet temperature sensor 18, flue direct injection regulating valve 19, pressure sensor 20, single-phase atomizing spray gun 21, atomization particle size monitor 22, crystallization regulating valve 23, salting-out crystallizer 24, 2#TDS detector 25, cooling water regulating valve 26.

[0054] Example

[0055] A system capable of achieving zero discharge and heat recovery of amine-containing wastewater in a carbon capture system, comprising a wastewater generation unit, a wastewater circulation concentration unit, an amine-containing steam heat / amine recovery unit, a high-salt concentrated water flue evaporation unit, a high-salt concentrated water desalination unit, a wastewater concentration monitoring system, a heat recovery coupling system, a water balance control system, and a terminal intelligent control system.

[0056] The wastewater generation unit includes an amine liquid circulation system outside the carbon capture absorption tower, an amine liquid heat-stable salt purification device, and a wastewater circulation box. The amine liquid outside the carbon capture absorption tower enters the amine liquid heat-stable salt purification device through a bypass pipeline, and returns to the amine liquid main pipeline after purification and quality improvement. The amine-containing wastewater generated by the amine liquid heat-stable salt purification device is pumped into the wastewater circulation box through a pipeline for circulation and concentration treatment. Among them, the water volume and water quality of the amine-containing wastewater are determined by the degree of amine liquid contamination in the carbon capture system.

[0057] The wastewater circulation and concentration unit includes a wastewater circulation box, a waste heat exchanger, a wastewater flash tank, a wastewater delivery pump, and a concentrated water circulation pump. An induced draft fan is used to extract high-temperature flue gas from the main flue, and heat is exchanged with amine-containing wastewater in the waste heat exchanger. After the heat exchange is completed, the flue gas returns to the main flue. The amine-containing wastewater is pumped into the waste heat exchanger through the wastewater delivery pump in the wastewater circulation box, and enters the wastewater flash tank after heating. The wastewater flash tank is a negative pressure environment, and the high-temperature amine-containing wastewater flashes in the tank. The generated water vapor carries organic amines, while the salt remains in the concentrated water, achieving wastewater concentration and reduction. If the concentration rate does not meet the design requirements, a concentrated water circulation pump is used to pump the concentrated water into the wastewater circulation box.

[0058] The amine-containing steam heat / amine recovery unit includes an amine-containing steam compressor, an energy level control unit, a small-stream rich liquid heat exchanger, and a condensate cooler. The amine-containing wastewater completes evaporation in the wastewater flash tank, and the amine-containing steam is generated and enters the amine-containing steam compressor. Under the control of the energy level control unit, the temperature and pressure are increased to a high enthalpy steam heat source. Subsequently, the amine-containing steam exchanges heat with a small-stream rich liquid in a small-stream rich liquid heat exchanger. After the heat exchange is completed, the amine-containing steam condenses, and the condensate is further cooled by the condensate cooler. After reaching the inlet temperature requirement of the carbon capture system, it is passed into the absorption tower to achieve amine recovery of the amine-containing wastewater. At the same time, the small-stream rich liquid is heated up after heat exchange to complete heat recovery, effectively reducing the steam consumption of the regeneration tower and reducing the regeneration heat consumption of the carbon capture system.

[0059] The high-salt concentrated water flue evaporation unit includes a high-salt concentrated water outlet pump, a flue direct injection regulating valve, and a single-phase atomizing spray gun. The flue direct injection regulating valve is opened, and the high-salt concentrated water is pumped into the single-phase atomizing spray gun through the high-pressure concentrated water outlet pump, and then sprayed into the main flue after efficient atomization. The high-salt concentrated water is completely evaporated by the heat of the high-temperature flue gas in the flue, and the generated water vapor is mixed into the flue gas. The salts in the concentrated water are precipitated and intercepted by the rear-end dust collector, achieving zero discharge of amine-containing wastewater.

[0060] The high-salt concentrated water desalination unit includes a high-salt concentrated water outlet pump, a crystallization regulating valve, and a salting-out crystallizer. The crystallization regulating valve is opened to pump the high-salt concentrated water into the salting-out crystallizer through the high-pressure concentrated water outlet pump. The salt in the high-salt concentrated water is crystallized by using the temperature difference change. The remaining concentrated water is returned to the wastewater circulation tank, and the crystallized salt is disposed of as solid waste. This treatment method can completely eliminate the risk of amine-containing wastewater discharge.

[0061] The wastewater concentration monitoring system includes 1#TDS detector, concentrated water circulation pump, wastewater regulating valve, and flue regulating valve. The 1#TDS detector is arranged at the bottom of the wastewater flash tank, which can monitor the dissolved salt content in the concentrated water in real time and serve as the basis for judging the wastewater concentration rate. The data of the 1#TDS detector is used as the system logic control point. If the dissolved salt content of the concentrated water in the wastewater flash tank is lower than the design range (30000-45000 mg / L), the concentrated water circulation pump is started to circulate and concentrate the concentrated water in the wastewater flash tank, wastewater circulation box, and waste heat exchanger. At the same time, the wastewater regulating valve and flue regulating valve can also be used to control the treatment amount of amine-containing wastewater and the amount of flue gas, so as to achieve precise control of the wastewater concentration rate.

[0062] The heat recovery coupling system includes an energy level control unit, an inlet temperature sensor, an outlet temperature sensor, and a small-stream rich liquid regulating valve. The energy level control unit is the control brain of the amine-containing steam compressor. When the inlet steam flow, temperature, and pressure of the amine-containing steam compressor fluctuate, the energy level control unit can stably output various levels of steam. The small-stream rich liquid regulating valve is coupled to control the solution flow, which can achieve precise control of the outlet temperature of the small-stream rich liquid, ensuring efficient heat recovery and system energy saving.

[0063] Amine steam condensate entering the absorption tower can easily cause abnormal fluctuations in the water balance of the carbon capture system. The water balance control system includes a rich liquid density detector, a condensate cooler, a wastewater regulating valve, and a flue gas regulating valve. The rich liquid density at the absorption tower outlet can accurately reflect the water balance of the carbon capture system. If the rich liquid density detector monitoring data deviates from the design range (1.050-1.120 mg / cm 3 ), the water balance control system starts to work. By controlling the opening of the wastewater regulating valve and the flue regulating valve, the amount of amine-containing steam generated in the wastewater flash tank is adjusted, and the amount of condensate entering the absorption tower is reduced or increased, so as to achieve effective control of the carbon capture water balance.

[0064] The terminal intelligent control system includes flue direct injection regulating valve, pressure sensor, single-phase atomizing spray gun, atomizing particle size monitor, crystallization regulating valve, and 2#TDS detector. The atomization effect of high-salt concentrated water through the single-phase atomizing spray gun is obtained through the pressure sensor and atomizing particle size monitor to ensure that the high-salt concentrated water is evaporated within the designed flue length; if the pipeline pressure or atomizing particle size deviates from the design range (pressure: 1.0~3.0MPa; atomizing particle size: 50~150μm), the flue direct injection regulating valve opening is adjusted to dynamically control to avoid adverse conditions such as flue slabs and blockages. The dissolved salt content of the concentrated water at the outlet of the salting-out crystallizer is monitored by the 2#TDS detector. If the monitored dissolved salt content deviates from the design range (8000~15000mg / L), the cooling water flow is adjusted to make the high-salt concentrated water obtain different temperature drops so as to adjust the single-cycle desalination amount and ensure that the dissolved salt content of the concentrated water at the outlet of the salting-out crystallizer meets the requirements.

[0065] A method for achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system using this embodiment includes the following steps:

[0066] (1) The amine liquid outside the carbon capture absorption tower enters the amine liquid heat-stabilized salt purification device through the bypass pipeline, and returns to the amine liquid main pipeline after purification and quality improvement. The amine-containing wastewater generated by the purification device is pumped into the wastewater circulation box 1 through the pipeline for circulation and concentration treatment.

[0067] (2) Start the induced draft fan 6 to extract high-temperature flue gas (150°C to 240°C) from the main flue between the power plant boiler and the dust collector and pass it into the waste heat exchanger 4. The flue gas volume is controlled by the flue regulating valve 5. The high-temperature flue gas enters the waste heat exchanger 4 from the upper part and is discharged from the lower part.

[0068] (3) The amine-containing wastewater in the wastewater circulation box 1 is pumped into the waste heat exchanger 4 through the wastewater delivery pump 2, and the wastewater flow rate is controlled by the wastewater regulating valve 3. The amine-containing wastewater and the high-temperature flue gas are subjected to countercurrent heat exchange to enhance the heat exchange efficiency.

[0069] (4) The high-temperature flue gas and the amine-containing wastewater exchange heat in the waste heat exchanger 4. The flue gas returns to the main flue after cooling down through heat exchange, and the amine-containing wastewater enters the wastewater flash tank 7 after heating up through heat exchange.

[0070] (5) The amine-containing wastewater is evaporated at low temperature under negative pressure in the wastewater flash tank 7, and the generated amine-containing steam is discharged from the upper exhaust port of the wastewater flash tank 7, and the remaining high-salt concentrated water is discharged from the lower drain port of the wastewater flash tank 7.

[0071] (6) A 1#TDS detector 9 is set at the bottom of the wastewater flash tank 7. The 1#TDS detector 9 can monitor the dissolved salt content of the concentrated water in real time as a basis for judging the wastewater concentration rate. If the dissolved salt content of the concentrated water is lower than the design range (30,000-45,000 mg / L), the concentrated water circulation pump 8 is started, so that the wastewater is circulated, heated and concentrated in the wastewater flash tank 7, the wastewater circulation box 1 and the waste heat exchanger 4. At the same time, the wastewater treatment volume and the flue gas volume are controlled by the wastewater regulating valve 3 and the flue gas regulating valve 5 to achieve precise control of the wastewater concentration rate. If the dissolved salt content of the concentrated water meets the design range, the high-salt concentrated water outlet pump 10 is started to enter the zero-emission treatment device.

[0072] (7) The exhaust port at the top of the wastewater flash tank 7 is connected to the air inlet of the amine-containing steam compressor 11. After the amine-containing steam enters the amine-containing steam compressor 11, the temperature and pressure are increased to become a high enthalpy steam heat source, and then enters the small rich liquid heat exchanger 13 to exchange heat with the rich liquid.

[0073] (8) The amine-containing steam compressor 11 is controlled by an energy level control unit 12. When the inlet steam flow, temperature and pressure of the amine-containing steam compressor 11 fluctuate, the energy level control unit 12 can stably output steam of various grades to ensure that the outlet steam quality reaches the system design range.

[0074] (9) Start the small rich liquid regulating valve 16 to allow the rich liquid to enter the small rich liquid heat exchanger 13 to exchange heat with the steam heat source. The small rich liquid heat exchanger 13 is provided with an inlet temperature sensor 17 and an outlet temperature sensor 18 respectively. After the rich liquid is heated, it enters the regeneration tower. The outlet temperature of the rich liquid is controlled by the heat recovery coupling system. The coupling control of the enthalpy of the amine-containing steam by the energy level control unit 12 and the rich liquid flow by the small rich liquid regulating valve 16 can achieve precise control of the outlet temperature of the small rich liquid.

[0075] (10) The amine-containing vapor is cooled and condensed after completing heat exchange in the small-stream rich liquid heat exchanger 13, and is further cooled by the condensate cooler 14. After reaching the required inlet temperature, it is passed into the absorption tower. Since the condensate carries organic amines, it enters the carbon capture system to recover the organic amines.

[0076] (11) The introduction of condensate can easily cause fluctuations in the water balance of the carbon capture system. This technical solution sets up a rich liquid density detector 15 to monitor the rich liquid density. If the density data deviates from the design range (1.050-1.120 mg / cm 3 ), the water balance control system is started. The water balance control system controls the opening of the wastewater regulating valve 3 and the flue regulating valve 5, adjusts the amount of amine-containing steam generated in the wastewater flash tank 7, reduces or increases the amount of condensate entering the absorption tower, and realizes effective regulation of carbon capture water balance.

[0077] (12) Following process (6), the high-salt concentrated water at the bottom of the wastewater flash tank 7 is pumped into a zero-emission treatment device through a high-salt concentrated water outlet pump 10. The zero-emission treatment device includes a flue direct injection device and a salt precipitation crystallization device.

[0078] (13) If the zero emission treatment is a flue direct injection device, start the high-salt concentrated water outlet pump 10, open the flue direct injection regulating valve 19, keep the crystallization regulating valve 23 closed, and spray the high-salt concentrated water directly into the main flue before the dust collector after being atomized by the single-phase atomizing spray gun 21. The high-salt concentrated water is completely evaporated by the heat of the high-temperature flue gas in the flue, and the generated water vapor is mixed into the flue gas. The salts in the high-salt concentrated water are precipitated and intercepted by the dust collector, thereby achieving zero emission of wastewater.

[0079] (14) The flue direct injection effect is guaranteed by the terminal intelligent control system provided by the patent. The monitoring data is provided by the pressure sensor 20 on the direct injection pipeline and the atomization particle size monitor 22 below the single-phase atomization spray gun 21 to obtain the atomization effect of high-salt concentrated water through the single-phase atomization spray gun 21, ensuring that the high-salt concentrated water is evaporated within the designed flue length. If the terminal intelligent control system finds that the direct injection pipeline pressure or atomization particle size deviates from the design range (pressure: 1.0-3.0MPa; atomization particle size: 50-150μm), the flue direct injection regulating valve 19 opening is immediately adjusted for dynamic control to avoid adverse conditions such as flue duct hardening and blockage.

[0080] (15) If the zero emission treatment is a salting-out crystallization device, start the high-salt concentrate outlet pump 10, open the crystallization regulating valve 23, keep the flue direct injection regulating valve 19 closed, and pass the high-salt concentrate into the salting-out crystallizer 24. The temperature difference is used to achieve the crystallization of salts in the high-salt concentrate. The remaining concentrate is returned to the wastewater circulation box 1 for recycling treatment. The crystallized salt is disposed of as solid waste, and the risk of amine-containing wastewater discharge is completely eliminated.

[0081] (16) The salting-out crystallization effect is guaranteed by the terminal intelligent control system provided by the patent. A 2# TDS detector 25 is arranged on the outlet pipe of the salting-out crystallizer 24, which can monitor the dissolved salt content of the concentrated water at the outlet of the salting-out crystallizer 24. If the monitoring data of the dissolved salt content of the concentrated water at the outlet deviates from the design range (8000-20000 mg / L), the terminal intelligent control system adjusts the opening of the cooling water regulating valve 26 to make the high-salt concentrated water obtain different temperature drops so as to adjust the single-cycle desalination amount, thereby ensuring that the dissolved salt content of the concentrated water at the outlet of the salting-out crystallizer meets the requirements.

[0082] Example 1

[0083] A domestic coal-fired power plant has a set of chemical absorption flue gas carbon capture device. After a long period of operation, the absorbent of the device degraded and the degradation products accumulated in the system, affecting the system CO 2 After purification with amine solution, CO 2 The output is increased, but the amine-containing wastewater generated is about 8t / d. How to deal with the amine-containing wastewater is a difficult problem faced by the power plant. Through the system and method for achieving zero discharge of wastewater and heat recovery of the carbon capture system provided in this embodiment, the low-cost zero discharge of amine-containing wastewater and the energy saving and consumption reduction of the coupled carbon capture system are achieved. Figure 2 shown.

[0084] A method for achieving zero wastewater discharge and heat recovery in a carbon capture system of a coal-fired power plant comprises the following steps:

[0085] Step 1: The amine-containing wastewater produced by the carbon capture system purification equipment of the power plant is 8 t / d. To ensure that the amine-containing wastewater can be completely treated, the wastewater system in this embodiment is designed to treat 0.5 t / h. The amine-containing wastewater is pumped into the wastewater circulation box 1 through a pipeline for circulation and concentration treatment.

[0086] Step 2: Start the induced draft fan 6, open the flue regulating valve 5, and extract a flow of about 9600Nm from the main flue between the boiler and the dust collector. 3 / h, high-temperature flue gas with a temperature of 175°C (accounting for about 7.9% of the total flue gas volume) is passed into the waste heat exchanger 4 to exchange heat with the amine-containing wastewater. The high-temperature flue gas enters from the upper part of the waste heat exchanger 4 and is discharged from the lower part.

[0087] Step 3: Amine-containing wastewater (temperature is 35°C) is pumped from the wastewater circulation box 1 into the waste heat exchanger 4 via the wastewater delivery pump 2. The wastewater flow is controlled by the wastewater regulating valve 3 and is heated to 98°C to 100°C after countercurrent heat exchange with the high-temperature flue gas.

[0088] Step 4: The high-temperature flue gas and the amine-containing wastewater are heat exchanged in the waste heat exchanger 4. After the flue gas is cooled by heat exchange, it returns to the main flue to continue the dust removal and desulfurization process. After the amine-containing wastewater is heated by heat exchange, it enters the wastewater flash tank 7.

[0089] Step 5: The design pressure of the wastewater flash tank 7 is -0.05MPa to -0.1MPa. The amine-containing wastewater is evaporated at low temperature under negative pressure to produce about 0.4t / h of amine-containing steam and about 0.1t / h of residual high-salt concentrated water. The wastewater concentration rate reaches 80%. The amine-containing steam is discharged from the upper exhaust port of the wastewater flash tank 7, and the high-salt concentrated water is discharged from the lower drain port of the wastewater flash tank 7.

[0090] Step 6: The dissolved salt content of the high-salt concentrated water in the wastewater flash tank 7 is monitored by the 1# TDS detector 9 and is 32550 mg / L, which meets the design range of the wastewater concentration monitoring system. Therefore, the high-salt concentrated water outlet pump 10 is started, and the high-pressure concentrated water enters the zero-discharge treatment device.

[0091] Step 7: The upper exhaust port of the wastewater flash tank 7 is connected to the air inlet of the amine-containing steam compressor 11, and 0.4 t / h amine-containing steam (temperature of about 100°C) enters the amine-containing steam compressor 11 to increase the temperature and pressure to a high enthalpy steam heat source (temperature of 120°C), and then enters the small rich liquid heat exchanger 13 to exchange heat with the rich liquid.

[0092] Step 8: The amine-containing steam compressor 11 is controlled by an energy level control unit 12. When the inlet steam flow, temperature and pressure of the amine-containing steam compressor 11 fluctuate, the energy level control unit 12 can stably output steam of various grades and different enthalpy values ​​to ensure that the outlet steam quality reaches the system design range.

[0093] Step 9: Start the small rich liquid regulating valve 16 and control about 8.0m 3 / h rich liquid enters the small rich liquid heat exchanger 13 to exchange heat with steam. The heat exchanger inlet temperature sensor 17 detects that the rich liquid temperature is 40.5°C. The heat exchanger inlet temperature sensor 18 detects that the rich liquid temperature is 65°C. After the temperature is raised, it enters the regeneration tower.

[0094] Step 10: After the amine-containing steam completes heat exchange in the small-stream rich liquid heat exchanger 13, the temperature is cooled from 120°C to 95°C and condenses, and is further cooled by the condensate cooler 14. After reaching the required inlet temperature, it is passed into the absorption tower to realize the recovery of organic amines in the amine-containing wastewater.

[0095] Step 11: The introduction of condensate may cause fluctuations in the water balance of the carbon capture system. The rich liquid density detector 15 monitors the rich liquid density to be 1.090 mg / cm 3 , which is in line with the design range of the absorption solution density of the carbon capture system, and there is no need to start the water balance control system.

[0096] Step 12: The high-salt concentrated water at the bottom of the wastewater flash tank 7 is pumped into a zero-emission treatment device through a high-salt concentrated water outlet pump 10. The zero-emission treatment device includes a flue direct injection device and a salting-out crystallization device. In Example 1, flue direct injection evaporation is used to achieve zero wastewater discharge.

[0097] Step 13: Start the high-salt concentrated water outlet pump 10, open the flue direct injection regulating valve 19, keep the crystallization regulating valve 23 closed, and spray the high-salt concentrated water (processing capacity 0.1t / h, temperature 100°C) directly into the main flue before the dust collector after being atomized by the single-phase atomizing spray gun 21.

[0098] Step 14: Use the total flow rate of 120600Nm in the main flue 3 / h, high-temperature flue gas with a temperature of 145℃ quickly evaporates high-salt concentrated water, water vapor and salt particles are mixed into the flue gas, the flue gas temperature is reduced to 144℃, the water content of the flue gas is increased by 0.04%, and the salt particles are retained by the dust collector.

[0099] Step 15: Use flue direct injection to evaporate high-salt concentrated water. The pressure sensor 20 arranged on the direct injection pipeline shows that the pipeline pressure is 1.5MPa. The atomization particle size monitor 22 under the single-phase atomization spray gun 21 detects that the particle size data is distributed in the range of 135 to 180μm, with an average of 158μm, which exceeds the atomization particle size design range (50 to 150μm) of the terminal intelligent control system, indicating that the current atomization effect is not good.

[0100] Step 16: Start the terminal intelligent control system and increase the opening of the flue direct injection regulating valve 19. At this time, the pressure sensor 20 shows that the pipeline pressure is 2.0MPa, and the atomization particle size monitor 22 detects that the particle size data is distributed between 90 and 135μm, with an average of 120μm, which is in line with the atomization particle size design range (50 to 150μm) of the terminal intelligent control system, thereby optimizing the atomization effect, avoiding adverse conditions such as flue compaction and blockage, and achieving zero wastewater discharge.

[0101] Implementation effect:

[0102] The system and method for zero-discharge and heat recovery of wastewater from the carbon capture system provided in this embodiment are used to successfully achieve low-cost zero-discharge treatment of amine-containing wastewater and energy saving and consumption reduction of the coupled carbon capture system. In Example 1, the zero-discharge treatment cost of amine-containing wastewater in this embodiment is only 72.5 yuan / ton, which is 63.66% lower than the conventional amine-containing wastewater treatment cost of 199.5 yuan / ton, greatly reducing the treatment cost of amine-containing wastewater. At the same time, the amine-containing wastewater heat recovery process provided in this embodiment is coupled with the carbon capture system for energy saving and consumption reduction, which can reduce steam consumption by about 5.0%.

[0103] Table 1 Comparison of the cost of wastewater treatment in this embodiment and conventional wastewater treatment

[0104]

[0105]

[0106] Example 2

[0107] A domestic gas power plant has built a set of chemical absorption flue gas carbon capture equipment. The amine liquid purification produces about 5t / d of amine-containing wastewater. Through the system and method for achieving zero discharge of wastewater and heat recovery of the carbon capture system provided in this embodiment, low-cost zero discharge of amine-containing wastewater and energy saving and consumption reduction of the coupled carbon capture system are achieved. Figure 3 shown.

[0108] A method for achieving zero wastewater discharge and heat recovery in a carbon capture system of a coal-fired power plant comprises the following steps:

[0109] Step 1: The amine-containing wastewater produced by the carbon capture system purification equipment of the power plant is 5t / d. To ensure that the amine-containing wastewater can be completely treated, the wastewater system in this embodiment is designed to treat 0.3t / h. The amine-containing wastewater is pumped into the wastewater circulation box 1 through a pipeline for circulation and concentration treatment.

[0110] Step 2: Start the induced draft fan 6, open the flue regulating valve 5, and extract a flow of about 4810Nm from the main flue between the boiler and the dust collector. 3 / h, high-temperature flue gas with a temperature of 210°C (accounting for about 4.0% of the total flue gas volume) is passed into the waste heat exchanger 4 to exchange heat with the amine-containing wastewater. The high-temperature flue gas enters from the upper part of the waste heat exchanger 4 and is discharged from the lower part.

[0111] Step 3: Amine-containing wastewater (temperature is 30°C) is pumped from the wastewater circulation box 1 into the waste heat exchanger 4 via the wastewater delivery pump 2. The wastewater flow is controlled by the wastewater regulating valve 3 and is heated to 99°C to 100°C after countercurrent heat exchange with the high-temperature flue gas.

[0112] Step 4: The high-temperature flue gas and the amine-containing wastewater are heat exchanged in the waste heat exchanger 4. The flue gas is cooled by heat exchange and returns to the main flue. The amine-containing wastewater is heated by heat exchange and enters the wastewater flash tank 7.

[0113] Step 5: The design pressure of the wastewater flash tank 7 is -0.05MPa to -0.1MPa, and the amine-containing wastewater is evaporated at low temperature under negative pressure conditions, generating about 0.15t / h of amine-containing steam and about 0.15t / h of remaining high-salt concentrated water, and the concentration rate of amine-containing wastewater is 50%. Among them, the amine-containing steam is discharged from the upper exhaust port of the wastewater flash tank 7, and the high-salt concentrated water is discharged from the lower drain port of the wastewater flash tank 7.

[0114] Step 6: The dissolved salt content of the high-salt concentrated water in the wastewater flash tank 7 is monitored by the 1# TDS detector 9 and is 27340 mg / L, which is lower than the design range of the wastewater concentration monitoring system. Therefore, the concentrated water circulation pump 8 is started to return the amine-containing wastewater from the wastewater flash tank 7 to the wastewater circulation box 1, and then pumped into the waste heat exchanger 4 through the wastewater delivery pump 2 for circulation and concentration.

[0115] Step 7: After circulating concentration, the wastewater flash tank 7 produces about 0.225t / h of steam, and the remaining high-salt concentrated water is about 0.075t / h, and the wastewater concentration rate reaches 75%. At this time, the 1#TDS detector 9 monitors the dissolved salt content of the high-salt concentrated water to be 34080mg / L, which meets the design range of the wastewater concentration monitoring system. Therefore, the high-salt concentrated water outlet pump 10 is started, and the high-salt concentrated water enters the zero-discharge treatment device.

[0116] Step 8: The upper exhaust port of the wastewater flash tank 7 is connected to the air inlet of the amine-containing steam compressor 11, and 0.225 t / h amine-containing steam (temperature of about 100°C) enters the amine-containing steam compressor 11 to increase the temperature and pressure to a high enthalpy steam heat source (temperature of 125°C), and then enters the small rich liquid heat exchanger 13 to exchange heat with the rich liquid.

[0117] Step 9: The amine-containing steam compressor 11 is controlled by an energy level control unit 12. When the inlet steam flow, temperature and pressure of the amine-containing steam compressor 11 fluctuate, the energy level control unit 12 can stably output steam of various grades and different enthalpy values ​​to ensure that the outlet steam quality meets the system requirements.

[0118] Step 10: Start the small rich liquid regulating valve 16 and control the flow rate to about 5.0m 3 / h rich liquid enters the small rich liquid heat exchanger 13 to exchange heat with steam. The heat exchanger inlet temperature sensor 17 detects that the rich liquid temperature is 40°C. The heat exchanger inlet temperature sensor 18 detects that the rich liquid temperature is 63.5°C. After the temperature is raised, it enters the regeneration tower.

[0119] Step 11: Since the heat consumption of the carbon capture system of the gas power plant is relatively high, it is required to improve the heat recovery efficiency to achieve further consumption reduction. Therefore, the heat recovery coupling system control is started, and the working energy level of the amine-containing steam compressor 11 is increased through the energy level control unit 12, and the outlet steam temperature is increased to 135°C, and enters the small-stream rich liquid heat exchanger 13 for heat exchange with the rich liquid.

[0120] Step 12: Amine-containing vapor and about 5.0m 3 After the rich liquid of / h completes heat exchange in the small-stream rich liquid heat exchanger 13, the rich liquid temperature measured by the heat exchanger inlet temperature sensor 18 increases from 63.5°C to 66°C, meeting the requirement of further consumption reduction of the carbon capture system.

[0121] Step 13: After the amine-containing steam completes heat exchange in the small-stream rich liquid heat exchanger 13, the temperature is cooled from 135°C to 95°C and condenses, and is further cooled by the condensate cooler 14. After reaching the required inlet temperature, it is passed into the absorption tower to realize the recovery of organic amines in the amine-containing wastewater.

[0122] Step 14: The introduction of condensate may cause fluctuations in the water balance of the carbon capture system. The rich liquid density detector 15 monitors the rich liquid density to be 1.065 mg / cm 3 , which is in line with the design range of the absorption solution density of the carbon capture system, and there is no need to start the water balance control system.

[0123] Step 15: The high-salt concentrated water at the bottom of the wastewater flash tank 7 is pumped into a zero-emission treatment device through a high-salt concentrated water outlet pump 10. The zero-emission treatment device includes a flue direct injection device and a salting-out crystallization device. In Example 2, the salting-out crystallization device is used to achieve zero wastewater discharge.

[0124] Step 16: Start the high-salt concentrated water outlet pump 10, open the cooling water regulating valve 26, open the crystallization regulating valve 23, keep the flue direct injection regulating valve 19 closed, and pass the high-salt concentrated water (processing capacity 0.075t / h, temperature 100°C) into the salting-out crystallizer 24 for cooling and crystallization. After cooling, the concentrated water temperature drops from 100°C to 55°C, and about 1kg of salt is precipitated and discharged from the bottom of the salting-out crystallizer 24 and disposed of as solid waste. At the same time, the upper concentrated water returns to the wastewater circulation box 1 and continues to be concentrated.

[0125] Step 17: The dissolved salt content of concentrated water in the outlet pipe of the salting-out crystallizer 24 is monitored by the 2# TDS detector 25 and is 7130 mg / L, which is lower than the design range of the terminal intelligent control system, indicating that the desalination effect of the salting-out crystallizer 24 is too good or the concentration ratio of the wastewater in the front-end wastewater flash tank 7 is insufficient.

[0126] Step 18: Start the terminal intelligent control system, immediately reduce the opening of the cooling water regulating valve 26, reduce the desalination effect of the salting-out crystallizer 24, and monitor the dissolved salt content of the mother liquor through the 2#TDS detector 25 to be 8705mg / L, which is within the design range of the terminal intelligent control system. However, this will cause the desalination processing capacity of the equipment to decrease.

[0127] Step 19: Keep the opening of the cooling water regulating valve 26 unchanged, start the terminal intelligent control system, and form a synergistic mechanism with the wastewater concentration monitoring system to improve the concentration rate of amine-containing wastewater. The dissolved salt content of high-salt concentrated water is monitored by the 1# TDS detector 9 to be 40185 mg / L, and the concentrated water terminal is treated with zero discharge.

[0128] Step 20: The high-salt concentrate precipitates about 2.5 kg of salt in the salting-out crystallizer 24. The 2# TDS detector 25 monitors the dissolved salt content of the concentrate at the outlet of the salting-out crystallizer 24 to be 8135 mg / L, which is within the design range of the terminal intelligent control system, completely eliminating the risk of wastewater discharge.

[0129] Implementation effect:

[0130] In Example 2, the total cost of zero-discharge treatment of amine-containing wastewater in this embodiment is only 84.5 yuan / ton, which is 57.64% lower than the conventional amine-containing wastewater treatment cost of 199.5 yuan / ton, greatly reducing the treatment cost of amine-containing wastewater. At the same time, the amine-containing wastewater heat recovery process provided in this embodiment is coupled with the carbon capture system to save energy and reduce consumption, and can reduce steam consumption by about 4.2%.

[0131] Table 2 Comparison of the cost of wastewater treatment in this embodiment and conventional wastewater treatment

[0132]

[0133]

[0134] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A system capable of achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system, characterized in that: It includes wastewater generation unit, wastewater circulation concentration unit, amine steam heat / amine recovery unit, high-salt concentrated water flue evaporation unit, high-salt concentrated water desalination unit, wastewater concentration monitoring system, heat recovery coupling system, water balance control system, and terminal intelligent control system.

2. A system for achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system according to claim 1, characterized in that: The wastewater circulation and concentration unit comprises a wastewater circulation box, a waste heat exchanger, a wastewater flash tank, a wastewater delivery pump, and a concentrated water circulation pump. The heat source of the wastewater circulation and concentration unit is high-temperature flue gas.

3. A system for achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system according to claim 1, characterized in that: The amine-containing steam heat / amine recovery unit comprises an amine-containing steam compressor, an energy level control unit, a small-stream rich liquid heat exchanger, and a condensate cooler.

4. A system for achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system according to claim 1, characterized in that: The high-salt concentrated water flue evaporation unit comprises a high-salt concentrated water outlet pump, a flue direct injection regulating valve, and a single-phase atomizing spray gun.

5. The system for achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system according to claim 1, characterized in that: The high-salt concentrated water desalination unit comprises a high-salt concentrated water outlet pump, a crystallization regulating valve, and a salting-out crystallizer.

6. A system and method for achieving zero discharge and heat recovery of amine-containing wastewater in a carbon capture system according to claim 1, characterized in that: The wastewater concentration monitoring system includes a 1# TDS detector, a concentrated water circulation pump, a wastewater regulating valve, and a flue regulating valve.

7. The system for achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system according to claim 1, characterized in that: The heat recovery coupling system includes an energy level control unit, an inlet temperature sensor, an outlet temperature sensor, and a small-stream rich liquid regulating valve.

8. The system for achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system according to claim 1, characterized in that: The water balance control system includes a rich liquid density detector, a condensate cooler, a wastewater regulating valve, and a flue regulating valve.

9. The system for achieving zero discharge and heat recovery of amine-containing wastewater from a carbon capture system according to claim 1, characterized in that: The terminal intelligent control system includes a flue direct injection regulating valve, a pressure sensor, a single-phase atomizing spray gun, an atomizing particle size monitor, a crystallization regulating valve, and a 2#TDS detector. The atomization effect of high-salt concentrated water is monitored and regulated by the pressure sensor and the atomizing particle size monitor, so that the atomizing pressure is 1.0-3.0 MPa and the atomizing particle size is 50-150 μm.

10. The method for achieving zero discharge and heat recovery of amine-containing wastewater in a carbon capture system according to claim 1, characterized in that: The steps include: (1) The amine liquid outside the carbon capture absorption tower enters the amine liquid heat-stable salt purification device through a bypass pipeline, and returns to the amine liquid main pipeline after purification and quality improvement; the amine-containing wastewater generated by the purification device enters the wastewater circulation box for circulating concentration treatment; (2) High-temperature flue gas is extracted from the main flue and passed into the waste heat exchanger. The flue gas volume is controlled by the flue regulating valve; (3) The amine-containing wastewater in the wastewater circulation box is passed into the waste heat exchanger, and the wastewater flow rate is controlled by the wastewater regulating valve; (4) The high-temperature flue gas and the amine-containing wastewater exchange heat in the waste heat exchanger. The flue gas returns to the main flue after heat exchange and cooling, and the amine-containing wastewater enters the wastewater flash tank after heat exchange and heating; (5) Amine-containing wastewater is evaporated at low temperature under negative pressure in a wastewater flash tank, and the generated amine-containing steam is discharged from the exhaust port at the top of the wastewater flash tank, and the remaining high-salt concentrated water is discharged from the drain port at the bottom of the wastewater flash tank; (6) Monitor the dissolved salt content of the concentrated water in real time through the 1# TDS detector. When the dissolved salt content of the concentrated water is lower than 30,000-45,000 mg / L, start the concentrated water circulation pump to circulate and heat the wastewater in the wastewater flash tank, wastewater circulation tank, and waste heat exchanger for concentration; if the dissolved salt content of the concentrated water is within the design range, it enters the zero emission treatment device; (7) After entering the amine-containing steam compressor, the amine-containing steam is heated and pressurized to become a steam heat source with a high enthalpy value, and then enters the small-stream rich liquid heat exchanger to exchange heat with the rich liquid; (8) When the steam flow, temperature and pressure at the inlet of the amine-containing steam compressor fluctuate, they are regulated by the energy level control unit; (9) Start the small-stream rich liquid regulating valve to allow the rich liquid to enter the small-stream rich liquid heat exchanger to exchange heat with the steam heat source. After the rich liquid is heated, it enters the regeneration tower; (10) The amine-containing vapor is cooled and condensed after completing heat exchange in the small-stream rich liquid heat exchanger, and is further cooled by the condensate cooler. After reaching the required inlet temperature, it is introduced into the absorption tower; (11) The rich liquid density detector monitors the rich liquid density. If the density data deviates from the design range of 1.050 to 1.120 mg / cm 3 , then start the water balance control system; (12) Following process (6), the high-salt concentrated water at the bottom of the wastewater flash tank is pumped into a zero-emission treatment device through a high-salt concentrated water outlet pump. The zero-emission treatment device includes a flue direct injection device and a salt precipitation crystallization device; When the zero emission treatment is a flue direct injection device, the high-salt concentrated water is atomized by a single-phase atomizing spray gun and then directly sprayed into the main flue before the dust collector. The high-salt concentrated water is completely evaporated by the heat of the high-temperature flue gas in the flue, and the generated water vapor is mixed into the flue gas. The salts in the high-salt concentrated water are precipitated and intercepted by the dust collector, achieving zero wastewater discharge; When the zero emission treatment is a salting-out crystallization device, high-salt concentrated water is passed into the salting-out crystallizer, and the temperature difference is used to achieve the crystallization of salts in the high-salt concentrated water. The remaining concentrated water is returned to the wastewater circulation tank for recycling treatment, and the crystallized salt is disposed of as solid waste to achieve zero wastewater emission.

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