Energy utilization system in wet desulphurization process

Abstract

The utility model discloses an energy utilization system in a wet desulphurization process, which at least comprises a first flue gas waste heat recoverer, a second flue gas waste heat recoverer and a third flue gas waste heat recoverer, the first flue gas waste heat recoverer is connected to a flue gas outlet pipeline washed by a fine washing tower and subjected to gas-liquid separation, and the first flue gas waste heat recoverer is used for carrying out heat exchange on washed low-temperature flue gas and high-temperature flue gas to be treated; the second flue gas waste heat recoverer is connected to a first branch of a water tank used for preparing spraying alkali liquor of the desulfurizing tower, and is used for heating part of water in the water tank for external use; the tower front flue gas precooler is arranged on a flue gas inlet pipeline of the desulfurization tower and is used for precooling and cooling the flue gas subjected to two times of heat exchange through the first flue gas waste heat recoverer and the second flue gas waste heat recoverer by utilizing external LNG cold energy; the circulating slurry cooler is arranged on a circulating slurry pipeline of the desulfurizing tower and is used for cooling the circulating slurry by using external LNG cold energy; and the circulating water cooler is arranged on the circulating water pipeline of the fine washing tower and is used for cooling the circulating water by using external LNG cold energy. Efficient stepped utilization of LNG cold energy and stepped utilization of high-temperature flue gas heat energy are achieved, and condensable particles can be removed.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of energy -conserving and environment -friendly engineering, especially relates to a energy utilization system in wet desulphurization process. BACKGROUND

[0002] LNG (Liquefied Natural Gas) is not only convenient to store and transport, and is the cleanest fossil energy, and its consumption is growing rapidly. LNG liquefies at atmospheric pressure at a temperature of -162 DEG C, and about 830 kJ of cold energy is released per kg of LNG during the gasification process. If this cold energy is used for power generation, assuming an efficiency of 100%, about 231 kW·h of electricity can be generated per ton of LNG using cold energy, so using LNG cold energy has great energy-saving and consumption-reducing potential.

[0003] Current main ways of LNG cold energy utilization include low-temperature power generation, air separation, dry ice production, low-temperature pulverization and rubber recovery. Because the temperature of LNG cold energy utilization increases from -162 DEG C to 10 DEG C, there is a large temperature rise, and after the current single-stage or multi-stage utilization process of LNG cold energy, there is still a problem of incomplete utilization of cold energy and low utilization efficiency.

[0004] An existing technical solution for LNG cold energy utilization in the field of low-temperature power generation is disclosed in Chinese patent CN202868298U, which discloses an LNG cold energy cascade utilization system, mainly comprising: an LNG storage tank, a BOG condensing device, an air separation device, a liquid carbon dioxide production device, a cold energy power generation device, a cold storage, and a flow regulating device; the LNG storage tank is connected to the BOG condensing device, the BOG condensing device is connected to a first flow regulating device, the first flow regulating device is connected to the air separation device, the cold energy power generation device, and a second flow regulating device; the air separation device is connected to the liquid carbon dioxide production device through a pipeline, the liquid carbon dioxide production device is connected to a gas supply pretreatment system through a heat exchanger, and the heat exchanger is connected to a medium cold storage; the cold energy power generation device is connected to the gas supply pretreatment system through a heat exchanger, and the heat exchanger is connected to a deep cold freezing storage and a low-temperature fresh-keeping storage in sequence; the second flow regulating device is connected to a vaporizer, the vaporizer is connected to a buffer zone, and the buffer zone is connected to the gas supply pretreatment system. This type of solution still has the problem of incomplete utilization of a portion of cold energy after using LNG cold energy for power generation.

[0005] Wet desulphurization process has the advantages of high desulphurization efficiency and absorbent utilization rate, and the by-products can be resourcefully utilized. However, in the wet desulphurization process, there is a phenomenon of secondary generation of condensable particulate matter, which causes the concentration of particulate matter in flue gas after desulphurization to exceed the standard, and the particulate pollution problem can be aggravated when the flue gas is discharged into the atmosphere. In addition, the flue gas at the inlet of the desulphurization tower needs to be pre-cooled, and the slurry after the desulphurization reaction needs to be cooled as circulating slurry, and these process procedures all need to provide external cold energy.

[0006] Therefore, there is an urgent need for an energy utilization system in a wet desulfurization process, which can not only utilize LNG cold energy to pre-cool flue gas at the inlet of a desulfurization tower, cool slurry after desulfurization reaction, but also cool circulating water of a polishing tower and remove condensable particulate matters in flue gas after desulfurization, so as to realize cascade utilization of LNG cold energy.

[0007] The information disclosed in this part of the background is only intended to increase the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art. Content of the present application

[0008] The present application aims to provide an energy utilization system in a wet desulfurization process, which can not only utilize external LNG cold energy to pre-cool flue gas at the inlet of a desulfurization tower through a tower front flue gas pre-cooler, but also cool slurry after desulfurization reaction through a circulating slurry cooler, and cool circulating water of a polishing tower through a circulating water cooler and remove condensable particulate matters in flue gas after desulfurization, so as to realize cascade utilization of LNG cold energy.

[0009] Another purpose of the present application is to provide an energy utilization system in a wet desulfurization process, which can not only utilize high-temperature flue gas to be treated to heat flue gas after washing of a polishing tower through a first flue gas waste heat recovery device, but also heat water used by a water tank for spraying alkali liquor through a second flue gas waste heat recovery device, so as to provide hot water externally and realize cascade utilization of high-temperature flue gas heat energy.

[0010] To achieve the above purpose, the present application provides an energy utilization system in a wet desulfurization process, which at least comprises: a first flue gas waste heat recovery device connected to an outlet pipeline of flue gas after washing and gas-liquid separation of a polishing tower, for heat exchange between low-temperature flue gas after washing and high-temperature flue gas to be treated, so as to form primary utilization of heat energy of high-temperature flue gas; a second flue gas waste heat recovery device connected to a first branch of a water tank for spraying alkali liquor of a desulfurization tower, for heating part of water in the water tank and supplying externally, so as to form secondary utilization of heat energy of high-temperature flue gas; a tower front flue gas pre-cooler arranged on a flue gas inlet pipeline of the desulfurization tower, for pre-cooling and cooling flue gas after twice heat exchange through the first and second flue gas waste heat recovery devices by utilizing external LNG cold energy, so as to form primary utilization of external LNG cold energy; a circulating slurry cooler arranged on a circulating slurry pipeline of the desulfurization tower, for cooling circulating slurry by utilizing external LNG cold energy, so as to form secondary utilization of external LNG cold energy; and a circulating water cooler arranged on a circulating water pipeline of the polishing tower, for cooling circulating water by utilizing external LNG cold energy, so as to form tertiary utilization of external LNG cold energy.

[0011] Furthermore, in the above technical solution, a first cold energy recovery device is installed on the refrigerant supply pipeline of the flue gas precooler in front of the tower; a second cold energy recovery device is installed on the refrigerant supply pipeline of the circulating slurry cooler; and a third cold energy recovery device is installed on the refrigerant supply pipeline of the circulating water cooler. The three cold energy recovery devices are used to exchange energy between the circulating refrigerant liquid and the external LNG cold energy in three stages.

[0012] Furthermore, in the above technical solution, the circulating water pipeline of the washing tower can be provided with two water supply branches, which are respectively located at the upper and lower parts of the washing tower, so as to form a spray of water from the upper and lower nozzles inside the washing tower.

[0013] Furthermore, in the above technical solution, a circulating water pump is installed on the circulating water pipeline of the washing tower; a water replenishment pipeline can be provided between the circulating water pump and the circulating water cooler, and a water replenishment tank and a water replenishment pump are provided on the water replenishment pipeline.

[0014] Furthermore, in the above technical solution, the bottom of the washing tower may be equipped with a motor-driven stirring blade, which is used to stir the washing water in the washing tower and enhance the dissolution and absorption of coagulable particles.

[0015] Furthermore, in the above technical solution, a flue gas outlet pipeline is provided at the top of the washing tower. A gas-liquid separator is connected to the flue gas outlet pipeline. The separated low-temperature flue gas can be heated by heat exchange in the first flue gas waste heat recovery unit before being discharged into the atmosphere.

[0016] Furthermore, in the above technical solution, the water tank used for configuring the alkaline solution spraying in the desulfurization tower can also be equipped with a second branch, on which an alkaline solution storage tank is connected in series to pump the configured alkaline solution into the alkaline solution sprayer in the desulfurization tower.

[0017] Furthermore, in the above technical solution, a first water pump is provided on the first branch; a second water pump is provided between the water tank and the alkali storage tank on the second branch, and an alkali pump is provided between the alkali storage tank and the desulfurization tower on the second branch.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) The system of this utility model can not only use external LNG cold energy to pre-cool the flue gas at the flue gas inlet of the desulfurization tower through the flue gas pre-cooler in front of the tower, but also cool the slurry after the desulfurization reaction through the circulating slurry cooler, and cool the circulating water of the fine washing tower through the circulating water cooler and remove condensable particulate matter in the flue gas after desulfurization, so as to realize the cascade utilization of LNG cold energy (that is, the three-level utilization of LNG cold energy).

[0020] 2) The system of this utility model can not only use the high-temperature flue gas to be treated to heat the flue gas after washing in the fine washing tower through the first flue gas waste heat recovery device (which helps to eliminate white smoke), but also heat part of the water in the spray alkali solution preparation water tank through the second flue gas waste heat recovery device, thereby providing hot water to the outside, realizing the cascade utilization of high-temperature flue gas heat energy (that is, the two-stage utilization of high-temperature flue gas heat energy).

[0021] 3) This utility model utilizes the combined effect of spraying water from the upper and lower nozzles inside the fine washing tower and stirring at the bottom of the fine washing tower to enhance the removal of condensable particulate matter present in the flue gas after desulfurization by using cooling circulating water.

[0022] 4) This utility model realizes the efficient tiered utilization of LNG cold energy and the tiered utilization of high-temperature flue gas heat energy, achieving the purpose of energy saving and consumption reduction while eliminating the formation of condensable particulate matter in wet desulfurization flue gas and its environmental pollution.

[0023] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of this utility model easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0024] Figure 1 This is a connection diagram of the energy utilization system in the wet desulfurization process of this utility model.

[0025] Explanation of key figure labels:

[0026] 1-Desulfurization tower, 11-Water tank, 111-First water pump, 112-Second water pump, 12-Alkali storage tank, 121-Alkali pump, 2-Finishing tower, 21-Motor, 22-Circulating water pump, 23-Makeup water tank, 24-Makeup water pump, 25-Gas-liquid separator, 3-Preheater of flue gas in front of the tower, 4-Circulating slurry cooler, 5-Circulating water cooler, 6-First flue gas waste heat recovery unit, 7-Second flue gas waste heat recovery unit, 8-First cold energy recovery unit, 9-Second cold energy recovery unit, 10-Third cold energy recovery unit. Detailed Implementation

[0027] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. However, it should be understood that the scope of protection of this utility model is not limited to the specific embodiments.

[0028] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0029] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0030] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0031] like Figure 1 As shown, this utility model provides an energy utilization system in a wet desulfurization process, comprising at least a first flue gas waste heat recovery unit 6, a second flue gas waste heat recovery unit 7, a pre-cooler for flue gas in front of the tower 3, a circulating slurry cooler 4, and a circulating water cooler 5. The first flue gas waste heat recovery unit 6 is connected to the outlet pipe of the flue gas after washing and gas-liquid separation in the fine washing tower 2, and is used to exchange heat between the washed low-temperature flue gas and the high-temperature flue gas to be treated, forming a primary utilization of the high-temperature flue gas's thermal energy. The second flue gas waste heat recovery unit 7 is connected to the first branch of the water tank 11 used for spraying alkaline solution in the desulfurization tower 1, and is used to heat part of the water in the water tank 11 for external use, forming a secondary utilization of the high-temperature flue gas's thermal energy. The pre-cooler 3 for flue gas in front of the desulfurization tower 1 is installed on the flue gas inlet pipe. It utilizes external LNG cold energy to pre-cool the flue gas after two heat exchanges (first flue gas waste heat recovery unit 6 and second flue gas waste heat recovery unit 7), forming the primary utilization of external LNG cold energy (which can reduce the inlet flue gas temperature of desulfurization tower 1 from 120℃ to about 80℃, reaching the flue gas temperature required for desulfurization). The circulating slurry cooler 4 is installed on the circulating slurry pipe of desulfurization tower 1, and uses external LNG cold energy to cool the circulating slurry, forming the secondary utilization of external LNG cold energy (which can improve the circulating slurry cooling efficiency by about 10%). The circulating water cooler 5 is installed on the circulating water pipe of the washing tower 2, and uses external LNG cold energy to cool the circulating water, forming the tertiary utilization of external LNG cold energy (the use of circulating cooling water can thoroughly wash the desulfurized flue gas, thereby dissolving and absorbing condensable particulate matter in the flue gas).

[0032] By adopting the above-mentioned technical solution of this utility model, not only can the external LNG cold energy be used to pre-cool the flue gas at the flue gas inlet of the desulfurization tower 1 through the flue gas pre-cooler 3, but also the slurry after desulfurization reaction can be cooled through the circulating slurry cooler 4, and the circulating water in the fine washing tower 2 can be cooled through the circulating water cooler 5, and the condensable particulate matter in the flue gas after desulfurization can be removed, thus realizing the cascade utilization of LNG cold energy (that is, the three-stage utilization of LNG cold energy); in addition, by adopting the system of this utility model, not only can the high-temperature flue gas to be treated be used to heat the flue gas after washing in the fine washing tower 2 through the first flue gas waste heat recovery unit 6 (which can eliminate white smoke before being discharged into the atmosphere), but also a portion of the water in the spray alkaline solution preparation water tank 11 can be heated through the second flue gas waste heat recovery unit 7, thereby providing hot water to the outside, thus realizing the cascade utilization of high-temperature flue gas heat energy (that is, the two-stage utilization of high-temperature flue gas heat energy).

[0033] Further as Figure 1 As shown, the refrigerant used in the pre-cooled flue gas system 3, circulating slurry cooler 4, and circulating water cooler 5 of this invention is a circulating refrigerant. This circulating refrigerant needs to absorb the cold energy from external LNG before supplying cooling to the wet desulfurization process of this invention. Therefore, this invention includes a first cold energy recovery unit 8 on the refrigerant supply pipeline of the pre-cooled flue gas system 3; a second cold energy recovery unit 9 on the refrigerant supply pipeline of the circulating slurry cooler 4; and a third cold energy recovery unit 10 on the refrigerant supply pipeline of the circulating water cooler 5. These three cold energy recovery units are used to sequentially exchange the circulating refrigerant with the cold energy of external LNG in a three-stage process.

[0034] Further as Figure 1 As shown, the circulating water pipeline of the washing tower 2 has two water supply branches, which are connected to the upper and lower parts of the washing tower 2 respectively, forming a spray of water from the upper and lower nozzles inside the washing tower 2. The bottom of the washing tower 2 is equipped with a stirring blade driven by a motor 21, which is used to stir the washing water inside the washing tower 2 and enhance the dissolution and absorption of condensable particulate matter. Through the synergistic effect of the spray from the upper and lower nozzles and the stirring at the bottom of the washing tower, the cooling circulating water can effectively remove condensable particulate matter present in the desulfurized flue gas.

[0035] Further as Figure 1 As shown, a circulating water pump 22 is installed on the circulating water pipeline of the washing tower 2; a water replenishment pipeline is provided between the circulating water pump 22 and the circulating water cooler 5, and a water replenishment tank 23 and a water replenishment pump 24 are provided on the water replenishment pipeline, which can replenish the circulating water in the washing tower 2 when the circulating water is insufficient.

[0036] Further as Figure 1As shown, the top of the washing tower 2 is equipped with a flue gas outlet pipe, which is connected to a gas-liquid separator 25. The low-temperature flue gas separated by the gas-liquid separator 25 is heated by heat exchange in the first flue gas waste heat recovery unit 6 and then discharged into the atmosphere, which can effectively eliminate the "white smoke" phenomenon.

[0037] Further as Figure 1 As shown, in addition to the first branch used to provide external hot water, the water tank 11 used for spraying alkaline solution in the desulfurization tower is also equipped with a second branch. An alkaline solution storage tank 12 is connected in series on the second branch to pump the prepared alkaline solution into the alkaline solution sprayer in the desulfurization tower 1. The alkaline solution comes into countercurrent contact with the flue gas in the desulfurization tower in a spraying manner and performs desulfurization treatment.

[0038] Further as Figure 1 As shown, a first water pump 111 is installed on the first branch of the aforementioned water tank 11. A second water pump 112 is installed between the water tank 11 and the alkali storage tank 12 on the second branch, and an alkali pump 121 is installed between the alkali storage tank 12 and the desulfurization tower 1 on the second branch. The second water pump 112 can pump water from the water tank 11 into the alkali storage tank 12, and then the alkali pump 121 can pump the prepared alkali solution into the desulfurization tower 1.

[0039] The process flow of this utility model system is described in detail below:

[0040] 1) The cold energy contained in LNG is transferred to the circulating refrigerant through three cold energy recovery units: LNG at -162°C from the LNG receiving terminal is sent to the first cold energy recovery unit 8, the second cold energy recovery unit 9, and the third cold energy recovery unit 10 in sequence through pipelines. Through three-stage recovery, the cold energy is transferred to the circulating refrigerant in stages, thereby providing the required cold energy for the inlet flue gas of desulfurization tower 1, the circulating slurry of desulfurization tower 1, and the circulating water of fine washing tower 2.

[0041] 2) The heat of the high-temperature flue gas to be treated is used to heat part of the water in the water tank 11 to provide hot water to the outside (that is, the secondary utilization of the high-temperature flue gas heat energy of this utility model): the high-temperature flue gas is subjected to waste heat recovery in the second flue gas waste heat recovery unit 7, and the heat is transferred to the demineralized water from the water tank 11; the water that has absorbed heat and been heated is sent to the outside (e.g., the factory area) to provide domestic hot water and heating water for the factory area.

[0042] 3) Utilizing circulating refrigerant to cool the hot flue gas at the inlet of desulfurization tower 1 and the circulating slurry at the bottom of desulfurization tower 1: After absorbing cold energy through the first cold energy recovery unit 8, the circulating refrigerant enters the flue gas precooler 3 in front of the tower to cool the flue gas at the inlet of desulfurization tower 1, which can reduce the inlet flue gas temperature from 120℃ to about 80℃; After heat exchange in the flue gas precooler 3 in front of the tower, the circulating refrigerant enters the circulating slurry cooler 4 after being cooled twice by the second cold energy recovery unit 6, which can cool the circulating slurry at the bottom of the desulfurization tower, thereby increasing the cooling efficiency of the circulating slurry by about 10%.

[0043] 4) The circulating cooling water in the washing tower 2 is cooled by circulating refrigerant liquid. The removal of condensable particulate matter in the flue gas after desulfurization is enhanced by bidirectional spraying of the circulating cooling water and stirring at the bottom of the washing tower 2: After the circulating refrigerant liquid absorbs cold energy through the third cold energy recovery unit 10, it enters the circulating water cooler 5 to exchange heat and cool the circulating water from the washing tower 2. The cooled water enters the upper and lower parts of the washing tower 2 in two directions to spray and cool the flue gas from the top of the desulfurization tower 1 in two directions. The flue gas temperature can be reduced from 51.5℃ to 35℃, which accelerates the removal of condensable particulate matter in the flue gas. The washing water is stirred by the stirring blades set at the bottom of the tower to enhance the dissolution and absorption of condensable particulate matter. The number concentration of condensable particulate matter in the flue gas decreases by about 40%, and the mass concentration decreases by about 60%.

[0044] 5) Utilizing the high-temperature flue gas to be treated to heat the exhaust gas at the top of the gas-liquid separator 25 (i.e., the primary utilization of high-temperature flue gas heat energy in this invention): The flue gas at the top of the scrubbing tower 2 enters the gas-liquid separator 25 for gas-liquid separation. The top gas enters the first flue gas waste heat recovery unit 6 to exchange heat with the high-temperature flue gas to be treated (i.e., the original flue gas), recovering the heat from the original flue gas. Through heat exchange, the temperature of the original flue gas can be reduced from 390℃ to about 260℃, and the temperature of the clean flue gas discharged from the top of the gas-liquid separator 25 is increased, raising the discharge temperature of the clean flue gas and helping to eliminate white smoke.

[0045] 6) The liquid separated at the bottom of the gas-liquid separator 25 is used as makeup water for circulating cooling water: The flue gas at the top of the washing tower 2 enters the gas-liquid separator 25 for gas-liquid separation, and the liquid water separated at the bottom can be used as makeup water for circulating cooling water.

[0046] This invention addresses the problems of LNG cold energy waste and the difficulty in removing condensable particulate matter from wet desulfurization flue gas. It designs a combined system integrating LNG cold energy recovery, high-temperature flue gas heat recovery for desulfurization and dust removal, and the removal of condensable particulate matter from the desulfurized flue gas. This system solves both the problem of cold energy waste and the difficulty of removing condensable particulate matter from wet desulfurization flue gas; it also allows the high-temperature raw flue gas to be used as a heat source for hot water in the plant area, recovering heat and reducing energy consumption. This achieves efficient, tiered utilization of LNG cold energy, eliminates the formation of condensable particulate matter in wet desulfurization flue gas and its environmental pollution, and achieves the goal of energy conservation and consumption reduction.

[0047] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the present invention and its practical applications, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the present invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the protection scope of the present invention.

Claims

1. An energy utilization system in a wet desulfurization process, characterized by, Comprise: The first flue gas waste heat recovery device is connected to the flue gas outlet pipeline after the washing and gas-liquid separation of the fine washing tower, and is used for heat exchange between the low-temperature flue gas after washing and the high-temperature flue gas to be treated, forming the first utilization of the heat energy of the high-temperature flue gas. The second flue gas waste heat recovery device is connected to the first branch of the water tank for configuring the spray alkali liquid of the desulfurization tower, and is used for heating part of the water in the water tank and supplying it to the outside, forming the second utilization of the heat energy of the high-temperature flue gas. The tower front flue gas pre-cooler is arranged on the flue gas inlet pipeline of the desulfurization tower, and is used for pre-cooling and cooling the flue gas after twice heat exchange of the first and second flue gas waste heat recovery devices by using the external LNG cold energy, forming the first utilization of the external LNG cold energy. The circulating slurry cooler is arranged on the circulating slurry pipeline of the desulfurization tower, and is used for cooling the circulating slurry by using the external LNG cold energy, forming the second utilization of the external LNG cold energy. The circulating water cooler is arranged on the circulating water pipeline of the fine washing tower, and is used for cooling the circulating water by using the external LNG cold energy, forming the third utilization of the external LNG cold energy.

2. The energy utilization system in a wet desulfurization process according to claim 1, characterized by, The first cold energy recovery device is arranged on the refrigerant supply pipeline of the tower front flue gas pre-cooler; the second cold energy recovery device is arranged on the refrigerant supply pipeline of the circulating slurry cooler; and the third cold energy recovery device is arranged on the refrigerant supply pipeline of the circulating water cooler; the three cold energy recovery devices are used for three-stage energy exchange between the circulating refrigerant liquid and the external LNG cold energy.

3. The energy utilization system in a wet desulfurization process according to claim 1, characterized by, The circulating water pipeline of the fine washing tower is provided with two water supply branches, which are arranged at the upper and lower parts of the fine washing tower respectively, forming the spray water pair spray of the upper and lower nozzles in the fine washing tower.

4. The energy utilization system in a wet desulfurization process according to claim 3, characterized by, The circulating water pipeline of the fine washing tower is provided with a circulating water pump; a water supplement pipeline is arranged between the circulating water pump and the circulating water cooler, and a water supplement tank and a water supplement pump are arranged on the water supplement pipeline.

5. The energy utilization system in a wet desulfurization process according to claim 4, characterized by, The bottom of the fine washing tower is provided with a motor-driven stirring paddle, which is used for stirring the washing water in the fine washing tower and strengthening the dissolution and absorption of the condensable particulate matter.

6. The energy utilization system in a wet desulfurization process according to claim 1, characterized by, The top of the fine washing tower is provided with a flue gas outlet pipeline, and a gas-liquid separator is connected to the flue gas outlet pipeline; the separated low-temperature flue gas is heated by the first flue gas waste heat recovery device and then discharged into the atmosphere.

7. The energy utilization system in a wet desulfurization process according to claim 1, characterized by, The water tank for configuring the spray alkali liquid of the desulfurization tower is also provided with a second branch, and an alkali liquid storage tank is arranged in series on the second branch, which is used for pumping the configured alkali liquid into the alkali liquid sprayer in the desulfurization tower.

8. The energy utilization system in a wet desulfurization process according to claim 7, characterized by, A first water pump is arranged on the first branch; a second water pump is arranged between the water tank and the alkali liquid storage tank on the second branch, and an alkali liquid pump is arranged between the alkali liquid storage tank on the second branch and the desulfurization tower.

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