Wet desulphurization device and method for boiler flue gas

Abstract

The invention relates to the technical field of coal-fired boiler flue gas pollutant control, and discloses a boiler flue gas wet desulphurization device and method. The device comprises a desulfurization tower and a heat recovery part, the top end of the desulfurization tower is provided with a tail gas outlet, a cavity at the bottom of the desulfurization tower forms a desulfurization slurry pond, the peripheral wall of the desulfurization tower is provided with a boiler flue gas inlet, and a slurry spraying layer used for spraying desulfurization slurry downwards is installed in the desulfurization tower located above the boiler flue gas inlet; and a heat absorption part of the heat recovery part is positioned in the desulfurization slurry pond so as to recover heat in the sulfur-containing slurry. According to the invention, effective utilization of wet desulphurization flue gas heat and desulphurization slurry heat is realized, energy conservation and emission reduction are realized, and carbon emission is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of coal-fired boiler flue gas pollutant control, and in particular to a boiler flue gas wet desulfurization device and method. Background Art

[0002] There is a large amount of SO2 gas in the flue gas of coal-fired boilers. In order to achieve the emission standard of SO2 in the flue gas of coal-fired boilers, desulfurization technology is often used to remove SO2 in the flue gas; among them, the most widely used is the limestone-gypsum wet desulfurization technology; the limestone-gypsum wet desulfurization technology has the advantages of fast reaction rate, high desulfurization efficiency, stable operation, and recoverable by-products, but it also has some shortcomings, such as high investment cost, large footprint, easy scaling and clogging of pipes and nozzles. The double alkali desulfurization technology was developed to overcome the easy scaling of the limestone-gypsum method. Sodium hydroxide solution is used as a desulfurizer for desulfurization in the tower. Since the sodium hydroxide desulfurizer has strong alkalinity, the solubility of the reaction product after absorbing sulfur dioxide is large, and it will not cause supersaturated crystallization and scaling and clogging problems; on the other hand, the desulfurization product is discharged into the regeneration pool for reduction and regeneration with calcium hydroxide, and the regenerated sodium hydroxide desulfurizer is returned to the desulfurization tower for recycling. However, in actual operation, the double alkali method also has some disadvantages, such as high operating costs, as sodium hydroxide is a relatively expensive desulfurizer; poor operating stability, and a relatively complex double alkali process, especially pH control. If the pH is too low, incomplete replacement will result in excessive consumption of sodium alkali; if the pH is too high, a large amount of excess calcium ions will not be able to precipitate and will enter the desulfurization system, causing scaling.

[0003] In addition, in the existing wet desulfurization system, the inlet flue gas temperature is about 100-130°C, the outlet flue gas is in a saturated state with a temperature of 45-55°C, and the slurry temperature in the desulfurization slurry pool is also 45-55°C. The outlet flue gas and desulfurization slurry contain a large amount of waste heat, which is usually wasted directly. How to collect the low-temperature waste heat in the flue gas and desulfurization slurry is the key to further energy conservation and emission reduction and reducing carbon emissions. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of direct waste of waste heat in the wet desulfurization system in the prior art, and to provide a boiler flue gas wet desulfurization device and method, which realizes the effective utilization of wet desulfurization flue gas heat and desulfurization slurry heat, achieves energy conservation and emission reduction, and reduces carbon emissions.

[0005] In order to achieve the above-mentioned object, the present invention provides a boiler flue gas wet desulfurization device on one hand, the wet desulfurization device comprising:

[0006] A desulfurization tower, wherein a tail gas outlet is provided at the top of the desulfurization tower and a cavity at the bottom is formed as a desulfurization slurry pool, a boiler flue gas inlet is provided on the peripheral wall of the desulfurization tower, and a slurry spraying layer for spraying desulfurization slurry downward is installed in the desulfurization tower located above the boiler flue gas inlet, and the boiler hot flue gas to be desulfurized entering the desulfurization tower from the boiler flue gas inlet is countercurrently contacted with the desulfurization slurry sprayed downward through the slurry spraying layer, and after desulfurization and heat and mass exchange, an upward tail gas and a downward sulfur-containing slurry are formed, and the tail gas is discharged from the tail gas outlet, and the sulfur-containing slurry flows into the desulfurization slurry pool;

[0007] A heat recovery component, wherein the heat absorption portion of the heat recovery component is located in the desulfurization slurry pool to recover the heat in the sulfur-containing slurry.

[0008] In some embodiments of the present invention, the heat recovery component comprises a heat pump unit, and a working medium flow pipeline of the heat pump unit is located in the desulfurization slurry pool.

[0009] In some embodiments of the present invention, the heat recovery unit preferably further includes a heat exchanger, the heat exchanger is located in the desulfurization slurry pool, the heat pump unit and the heat exchanger are used in combination, and more preferably the heat exchange efficiency of the heat exchanger is greater than 95%.

[0010] In some embodiments of the present invention, the heat pump unit preferably includes an air source heat pump and / or a water source heat pump.

[0011] In some embodiments of the present invention, the energy efficiency ratio of the heat pump unit is preferably greater than 3.

[0012] A second aspect of the present invention provides a method for wet desulfurization of boiler flue gas, the method using the wet desulfurization device for boiler flue gas of the present invention, comprising the following:

[0013] The boiler hot flue gas is fed into the desulfurization tower through the boiler flue gas inlet, and the desulfurization slurry is sprayed downward through the slurry spray layer, and countercurrently contacts with the upward boiler hot flue gas. After desulfurization and heat and mass exchange, upward tail gas and downward sulfur-containing slurry are formed. The tail gas is discharged from the tail gas outlet, and the sulfur-containing slurry flows into the desulfurization slurry pool. The heat of the sulfur-containing slurry in the desulfurization slurry pool is recovered by the heat recovery component.

[0014] Through the above technical solution, the present invention has the following advantages:

[0015] 1. The wet desulfurization technology of the present invention uses chemical byproduct sodium carbonate as a desulfurization absorbent. Compared with sodium hydroxide as an absorbent, the absorbent cost is greatly reduced; in addition, sodium hydroxide, as a strong base, has higher requirements on the instruments and equipment and operation of the desulfurization system;

[0016] 2. The present invention can effectively reduce the operating temperature of the desulfurization slurry by setting a desulfurization slurry heat exchanger in the desulfurization tower slurry pool. Compared with conventional wet desulfurization, the slurry temperature can be reduced from the original 45-55°C to 25-35°C, which can effectively increase the solubility of SO2 in the flue gas in the desulfurization slurry, increase the mass transfer efficiency, and thus improve the desulfurization efficiency. The desulfurization efficiency can reach more than 99%, and the outlet SO2 concentration can be controlled at 10mg / m 3 the following;

[0017] 3. While reducing the temperature of the desulfurized slurry, the present invention also reduces the temperature of the flue gas after desulfurization to 25-35°C, which can reduce the amount of evaporated water in the saturated flue gas, effectively reduce the water consumption of the desulfurization system, and save water;

[0018] 4. The present invention arranges the desulfurization slurry heat exchanger in the desulfurization slurry pool. Compared with arranging the heat exchanger in the flue or the slurry circulation pipeline, it will not cause the resistance of the flue or the slurry circulation pipeline to increase, nor will it cause the increase of the power consumption of the induced draft fan or the slurry circulation pump;

[0019] 5. The present invention transfers the heat of the desulfurized flue gas to the slurry heat exchanger through the desulfurized circulating slurry, and further utilizes the heat comprehensively through the heat pump unit, thereby realizing the effective utilization of the heat of the wet desulfurized flue gas and the heat of the desulfurized slurry, achieving energy conservation and emission reduction, and reducing carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a boiler flue gas wet desulfurization device for illustrating a specific implementation mode of the present invention.

[0021] Description of Reference Numerals

[0022] 1 desulfurization tower; 2 heat exchanger; 3 heat pump unit; 10 drainage pump; 11 flue gas inlet; 12 desulfurization slurry pool; 13 desulfurization slurry circulation pipe; 14 tail gas outlet; 15 flow equalization component in the tower; 16 slurry spray layer; 17 demisting layer; 18 liquid inlet pump; 19 circulation pump. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.The endpoints and any values ​​of the scope disclosed in this article are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values.For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in this article.

[0024] In the present invention, unless otherwise specified, directional words such as "up, down, left, right" generally refer to up, down, left, right as shown in the reference drawings; "inside and outside" refer to inside and outside relative to the outline of each component itself.

[0025] In one aspect, the present invention discloses a boiler flue gas wet desulfurization device, the wet desulfurization device comprising:

[0026] A desulfurization tower 1, wherein a tail gas outlet 14 is provided at the top of the desulfurization tower 1 and a cavity at the bottom is formed as a desulfurization slurry pool 12, a boiler flue gas inlet 11 is provided on the peripheral wall of the desulfurization tower 1, and a slurry spraying layer 16 for spraying desulfurization slurry downward is installed in the desulfurization tower 1 located above the boiler flue gas inlet 11, and the boiler hot flue gas to be desulfurized entering the desulfurization tower 1 from the boiler flue gas inlet 11 is countercurrently contacted with the desulfurization slurry sprayed downward through the slurry spraying layer 16, and after desulfurization and heat and mass exchange, an upward tail gas and a downward sulfur-containing slurry are formed, and the tail gas is discharged from the tail gas outlet 14, and the sulfur-containing slurry flows into the desulfurization slurry pool 12;

[0027] The heat recovery component has a heat absorption portion located below the liquid surface of the desulfurization slurry pool 12 to recover heat from the sulfur-containing slurry.

[0028] The present invention can reduce the operating temperature of the desulfurization slurry by setting a heat recovery unit in the desulfurization slurry pool, thereby increasing the solubility of SO2 in the flue gas in the desulfurization slurry, increasing the mass transfer efficiency, and thus improving the desulfurization efficiency. As shown in Example 1 of the present invention, the desulfurization efficiency can reach more than 99%, and the SO2 concentration at the tail gas outlet is controlled at 10 mg / m 3 the following.

[0029] The present invention reduces the temperature of the desulfurized slurry and also reduces the temperature of the flue gas after desulfurization (for example, to 25-35° C.), which can reduce the amount of evaporated water in the saturated flue gas, effectively reduce the water consumption of the desulfurization system, and save water.

[0030] The present invention places the heat absorbing part of the heat recovery element in the desulfurization slurry pool 12. Compared with setting a heat exchanger in the flue or the desulfurization slurry circulation pipe, it will not cause an increase in the resistance of the flue or the desulfurization slurry circulation pipe.

[0031] To achieve heat recovery, in some embodiments of the present invention, the heat recovery component includes a heat pump unit 3 , and a working medium flow pipeline of the heat pump unit is located below the liquid surface of the desulfurization slurry pool 12 .

[0032] In order to improve the heat recovery efficiency, in other embodiments of the present invention, the heat recovery component preferably also includes a heat exchanger 2, and the heat exchanger is located in the desulfurization slurry pool 12. The heat pump unit 3 and the heat exchanger 2 are used in combination. In this way, the heat exchanger is used to absorb the heat in the slurry, and the heat pump unit is used to reuse the heat absorbed by the heat exchanger (for example, for heating hot network water or process hot water, boiler inlet air heating, furnace front fuel heating, etc.), thereby realizing the recovery and reuse of heat in the desulfurization system. It is more preferred that the heat exchange efficiency of the heat exchanger 2 is greater than 95%.

[0033] In the present invention, there is no special requirement for the selection of heat pumps, and commonly used heat pumps can be used in the present invention. The following exemplary description does not limit the scope of the present invention. In some embodiments of the present invention, the heat pump unit 3 includes an air source heat pump and / or a water source heat pump.

[0034] In some embodiments of the present invention, the energy efficiency ratio of the heat pump unit 3 is preferably greater than 3.

[0035] In some embodiments of the present invention, the wet desulfurization device includes a desulfurization slurry circulation pipe 13 and a circulation pump 19 installed on the desulfurization slurry circulation pipe 13. The desulfurization slurry pool 12 and the slurry spray layer 16 are connected by at least one desulfurization slurry circulation pipe 13. It can be understood that a circulation pump is installed on each desulfurization slurry circulation pipe 13, or multiple desulfurization slurry circulation pipes 13 can share one circulation pump. The present invention has no special requirements for this and can be selected according to actual working conditions.

[0036] In some embodiments of the present invention, the bottom of the desulfurization tower 1 is connected to a slurry discharge pipe equipped with a drainage pump 10, and the slurry discharge pipeline is connected to a slurry treatment system. There are no special requirements for the slurry treatment system in the present invention, which will not be described in detail here.

[0037] To improve the desulfurization effect, in some embodiments of the present invention, an in-tower flow equalization component 15 is installed below the slurry spraying layer 16, and the in-tower flow equalization component is used to perform secondary dispersion on the desulfurization slurry after primary dispersion through the slurry spraying layer 16.

[0038] In order to improve the desulfurization effect, in some embodiments of the present invention, it is preferred that a plurality of slurry spray layers 16 are provided, and the plurality of slurry spray layers 16 are spaced apart along the height direction of the desulfurization tower 1; more preferably, the number of slurry spray layers 16 is 2-5, wherein the spacing between two adjacent slurry spray layers 16 is 1.8-2.2 m, and further preferably 2 m.

[0039] In some embodiments of the present invention, each slurry spray layer includes at least one liquid distributor;

[0040] In some embodiments of the present invention, the flow balancing component in the tower is installed below the lowest slurry spray layer, and includes at least one tower plate, and a plurality of distribution holes are provided on the tower plate.

[0041] In some embodiments of the present invention, a desulfurizer feed pipeline with a liquid feed pump 18 installed is connected to the wall of the desulfurization tower 1 located below the boiler flue gas inlet 11, and fresh desulfurizer can be fed into the desulfurization tower through the desulfurizer feed pipeline. It can be understood that the desulfurizer feed pipeline can also be connected to the liquid inlet of the liquid distributor. In this way, the desulfurizer can be directly fed into the desulfurization slurry pool 12, and the desulfurization slurry can also be fed through the liquid distributor.

[0042] In some embodiments of the present invention, each liquid distributor is connected to the desulfurization slurry pool via a desulfurization slurry circulation pipe 13 equipped with a circulation pump 19.

[0043] In the present invention, there are no special requirements for the liquid distributor and the tower tray. Commonly used liquid distributors and tower trays can be used in the present invention. The following exemplary description does not limit the scope of the present invention. In some embodiments of the present invention, the liquid distributor is configured as a sprayer, and the sprayer makes the slurry atomization particle size 2200μm, the porosity of the tower tray is 25-45%, and the diameter of the distribution hole is 25-35mm.

[0044] In some embodiments of the present invention, a demisting layer 17 is provided between the tail gas outlet 14 and the slurry spraying layer 16 .

[0045] In some embodiments of the present invention, it is preferred that the demisting layer 17 is provided with multiple layers, and the multiple layers of demisting layers 17 are arranged at intervals along the height direction.

[0046] In some embodiments of the present invention, the demisting layer 17 is preferably provided with 2-3 layers. For example, the distance between two adjacent demisting layers may be 1 m, and the distance between the bottom demisting layer and the top spray layer may be 2 m.

[0047] In some embodiments of the present invention, a demister is preferably installed in the demister layer 17, and process water is sprayed up and down by the demister intermittently, which has the function of preventing the desulfurization slurry from clogging the demister and replenishing water into the desulfurization tower, thereby preventing the liquid level in the desulfurization slurry pool from being too low.

[0048] Another aspect of the present invention provides a method for wet desulfurization of boiler flue gas, which adopts the wet desulfurization device for boiler flue gas of the present invention, and comprises the following:

[0049] Boiler hot flue gas is fed into the desulfurization tower 1 through the boiler flue gas inlet 14, and desulfurization slurry is sprayed downward through the slurry spray layer 16, and countercurrently contacts with the upward boiler hot flue gas. SO2 in the boiler hot flue gas is absorbed by the desulfurization slurry, and after heat and mass exchange, upward tail gas and downward sulfur-containing slurry are formed. The tail gas is discharged from the tail gas outlet 14, and the sulfur-containing slurry flows into the desulfurization slurry pool 12, and the heat of the sulfur-containing slurry in the desulfurization slurry pool is recovered by the heat recovery component.

[0050] In some embodiments of the present invention, the heat of the sulfur-containing slurry in the desulfurization slurry pool is transferred to the heat pump unit after heat exchange through the heat exchanger, and the heat pump unit recovers the heat for reuse.

[0051] In some embodiments of the present invention, the sulfur-containing slurry in the desulfurization slurry pool 12 is transported to the slurry spraying layer 16 through the desulfurization slurry circulation pipe 13 to realize the recycling of the slurry.

[0052] In some embodiments of the present invention, the desulfurization slurry is selected from a sodium hydroxide aqueous solution and / or a sodium carbonate aqueous solution, preferably a sodium carbonate aqueous solution, and more preferably the desulfurization slurry is a 15-25 wt % sodium carbonate aqueous solution.

[0053] In some embodiments of the present invention, the sodium carbonate aqueous solution is selected from chemical by-products. Thus, the present invention uses sodium carbonate, a chemical by-product, as a desulfurization absorbent. Compared with using sodium hydroxide as an absorbent, the absorbent cost is greatly reduced. In addition, sodium hydroxide, as a strong base, has higher requirements on the instruments and equipment and operation of the desulfurization system. The present invention reduces the requirements on equipment and operation.

[0054] In some embodiments of the present invention, the composition of boiler flue gas includes N2, CO2, O2, SO2 and NO x At least one of .

[0055] According to research, when the pH is lower than 5.5, it means that the content of NaCO3 in the desulfurization slurry used to react with SO2 is too low, resulting in reduced desulfurization efficiency and excessive SO2 emission concentration in the flue gas; when the pH is higher than 7.0, it means that the content of NaCO3 in the desulfurization slurry used to react with SO2 is too high, resulting in a waste of desulfurizer; in some embodiments of the present invention, the pH of the slurry in the desulfurization slurry pool 12 is 5.5-7.0, preferably 6.0-6.3.

[0056] In the present invention, the discharge of desulfurized slurry is controlled by density. When the slurry density is greater than 1.18 g / cm 3 When the desulfurization slurry is too high, it means that too much NaSO3 is generated in the slurry. The desulfurization slurry pool needs to discharge part of the desulfurization slurry through the discharge pump; then the demister is used to add water to dilute the density of the desulfurization slurry pool to between 1.05 and 1.18. In some embodiments of the present invention, the density of the slurry in the desulfurization slurry pool 12 is 1.05-1.18 g / cm3 .

[0057] In some embodiments of the present invention, when the pH of the slurry is lower than 5.5, a 15-25 wt % sodium carbonate aqueous solution is fed through the desulfurizing agent feeding pipeline.

[0058] In some embodiments of the present invention, when the slurry density is greater than 1.18 g / cm 3 When the slurry is discharged from the slurry discharge pipe to the slurry treatment system.

[0059] In some embodiments of the present invention, the temperature of the slurry in the desulfurization slurry pool 12 after heat exchange in the heat exchanger 2 is 25-35°C; the temperature of the flue gas from the tail gas outlet 14 is 25-35°C.

[0060] The advantages of the present invention will be described below by way of examples, but the present invention is not limited thereto.

[0061] Example 1

[0062] Use Figure 1 The boiler flue gas wet desulfurization device shown in the figure comprises: a desulfurization tower 1, a tail gas outlet 14 is provided at the top of the desulfurization tower 1 and a cavity at the bottom is formed as a desulfurization slurry pool 12, a boiler flue gas inlet 11 is provided on the peripheral wall of the desulfurization tower 1, and three slurry spraying layers 16 are installed in the desulfurization tower 1 above the boiler flue gas inlet 11. Along the height direction of the desulfurization tower 1, the three slurry spraying layers 16 are arranged at intervals, and the adjacent intervals are 2m. Each slurry spraying layer 16 is connected to a desulfurization slurry circulation pipe 13 equipped with a circulation pump 19. It is connected to the desulfurization slurry pool; a tower plate is installed below the bottom slurry spray layer 16, and a plurality of distribution holes with a diameter of 30 mm are opened on the tower plate, with an opening rate of 30%; a plurality of demisters arranged at intervals along the height direction are arranged between the tail gas outlet 14 and the slurry spray layer 16; wherein a sprayer is installed in the slurry spray layer; a desulfurizer feed pipeline with a liquid feed pump 18 installed is connected to the tower wall of the desulfurization tower 1 located below the boiler flue gas inlet 11, and a slurry discharge pipe with a drainage pump 10 installed is connected to the bottom of the desulfurization tower 1.

[0063] A heat exchanger 2 is installed under the liquid surface of the desulfurization slurry pool 12, and the heat exchanger 2 is connected to a heat pump unit 3. The heat exchange efficiency of the heat exchanger 2 is 95%. The heat pump unit 3 adopts an air source heat pump, and the energy efficiency ratio of the heat pump unit 3 is 3.

[0064] A 20 wt% sodium carbonate aqueous solution is fed into the desulfurizer feed pipeline, and the boiler hot flue gas is fed into the boiler flue gas inlet 14. The boiler hot flue gas comes from a coal boiler and contains N2, CO2, O2, SO2 and NO. x etc., where the SO2 concentration is 1000 mg / m 3The slurry spray layer 16 sprays sodium carbonate aqueous solution downward, which contacts with the upward boiler hot flue gas in countercurrent. The SO2 in the boiler hot flue gas is absorbed by the sodium carbonate aqueous solution, and the tail gas is discharged from the tail gas outlet 14. The sodium carbonate aqueous solution that absorbs SO2 flows into the desulfurization slurry pool 12, and the heat of the sulfur-containing slurry in the desulfurization slurry pool is recovered through the heat exchanger and the heat pump unit.

[0065] The pH of the slurry in the desulfurization slurry pool 12 is 6.0 and the density is 1.12 g / cm 3 ; When the pH of the slurry is lower than 5.5, a 20 wt% sodium carbonate aqueous solution is fed through the desulfurizer feed pipeline to control the pH of the desulfurization tower slurry at 6.0;

[0066] When the slurry density is greater than 1.18 g / cm 3 When the slurry is discharged through the slurry discharge pipe, the desulfurized slurry density is 1.12g / cm 3 .

[0067] Results: The slurry temperature in the desulfurization slurry pool 12 after heat exchange in the heat exchanger 2 is 30°C; the flue gas temperature from the tail gas outlet 14 is 30°C, the desulfurization efficiency is 99.5%, and the SO2 concentration in the tail gas discharged from the tail gas outlet 14 is 5mg / m 3 .

[0068] Example 2

[0069] The difference from the first embodiment is that the heat exchange efficiency of the heat exchanger 2 is 93%, and the energy efficiency ratio of the heat pump unit 3 is 2.9.

[0070] The desulfurization agent feed pipeline feeds 24wt% sodium carbonate aqueous solution. The slurry pH in the desulfurization slurry pool 12 is 5.8 and the density is 1.11g / cm 3 ;

[0071] Results: The slurry temperature in the desulfurization slurry pool 12 after heat exchange in the heat exchanger 2 is 32°C; the flue gas temperature from the tail gas outlet 14 is 32°C, the desulfurization efficiency is 99%, and the SO2 concentration in the tail gas discharged from the tail gas outlet 14 is 10mg / m 3 .

[0072] Example 3

[0073] The difference from the first embodiment is that the heat exchange efficiency of the heat exchanger 2 is 90%, and the energy efficiency ratio of the heat pump unit 3 is 2.85.

[0074] A 16 wt% sodium carbonate aqueous solution is fed into the desulfurization agent feed pipeline. The pH of the slurry in the desulfurization slurry pool 12 is 5.6 and the density is 1.10 g / cm 3 ;

[0075] Results: The slurry temperature in the desulfurization slurry pool 12 after heat exchange in the heat exchanger 2 is 35°C; the flue gas temperature from the tail gas outlet 14 is 35°C, the desulfurization efficiency is 98.5%, and the SO2 concentration in the tail gas discharged from the tail gas outlet 14 is 15mg / m 3 .

[0076] Example 4

[0077] Different from Example 1, when the pH of the slurry is lower than 5.5, the sodium carbonate aqueous solution is not fed into the desulfurization tower.

[0078] Results: Desulfurization efficiency is 96.5%, SO2 concentration in tail gas discharged from tail gas outlet 14 is 35mg / m 3 As time goes by, the pH value of the slurry gradually decreases, the desulfurization efficiency decreases, and the outlet SO2 concentration continues to increase.

[0079] Example 5

[0080] The difference from Example 1 is that when the slurry density is greater than 1.18 g / cm 3 No material is discharged externally.

[0081] Results: Desulfurization efficiency is 97.5%, SO2 concentration in tail gas discharged from tail gas outlet 14 is 25mg / m 3 .

[0082] Example 6

[0083] Different from Example 1, the desulfurization slurry fed into the desulfurization tower is 20 wt% CaCO3 slurry.

[0084] Results: The slurry temperature in the desulfurization slurry pool 12 after heat exchange in the heat exchanger 2 is 30°C; the flue gas temperature from the tail gas outlet 14 is 30°C, the desulfurization efficiency is 98.0%, and the SO2 concentration in the tail gas discharged from the tail gas outlet 14 is 20mg / m 3 .

[0085] Comparative Example 1

[0086] The difference from the first embodiment is that the heat exchanger 2 and the heat pump unit 3 are not provided.

[0087] Results: The slurry temperature in the desulfurization slurry pool 12 is 55°C; the flue gas temperature from the tail gas outlet 14 is 55°C, the desulfurization efficiency is 97.0%, and the SO2 concentration in the tail gas discharged from the tail gas outlet 14 is 30mg / m 3 .

[0088] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any appropriate manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A boiler flue gas wet desulfurization device, characterized in that: The wet desulfurization device comprises: A desulfurization tower (1), wherein a tail gas outlet (14) is provided at the top of the desulfurization tower (1) and a cavity at the bottom is formed as a desulfurization slurry pool (12); a boiler flue gas inlet (11) is provided on the peripheral wall of the desulfurization tower (1); a slurry spraying layer (16) for spraying desulfurization slurry downward is provided in the desulfurization tower (1) above the boiler flue gas inlet (11); the boiler hot flue gas to be desulfurized entering the desulfurization tower (1) from the boiler flue gas inlet (11) is countercurrently contacted with the desulfurization slurry sprayed downward through the slurry spraying layer (16); after desulfurization and heat and mass exchange, tail gas flowing upward and sulfur-containing slurry flowing downward are formed; the tail gas is discharged from the tail gas outlet (14), and the sulfur-containing slurry flows into the desulfurization slurry pool (12); A heat recovery component, wherein the heat absorption portion of the heat recovery component is located in the desulfurization slurry pool (12) to recover the heat in the desulfurization slurry pool.

2. The boiler flue gas wet desulfurization device according to claim 1, characterized in that: The heat recovery component comprises a heat pump unit (3), and a working medium flow pipeline of the heat pump unit is located in the desulfurization slurry pool (12); Preferably, the heat recovery unit further comprises a heat exchanger (2), the heat exchanger (2) is located in the desulfurized slurry pool (12), the heat pump unit (3) and the heat exchanger (2) are used in combination, and more preferably, the heat exchange efficiency of the heat exchanger (2) is greater than 95%; and / or Preferably, the heat pump unit (3) comprises an air source heat pump and / or a water source heat pump; and / or Preferably, the energy efficiency ratio of the heat pump unit (3) is greater than 3.

3. The boiler flue gas wet desulfurization device according to claim 1, characterized in that: The wet desulfurization device comprises a desulfurization slurry circulation pipe (13) and a circulation pump (19) installed on the desulfurization slurry circulation pipe (13), and the desulfurization slurry pool (12) and the slurry spray layer (16) are connected through at least one desulfurization slurry circulation pipe (13); and / or The desulfurization tower (1) is connected to a desulfurization agent feed pipeline equipped with a liquid feed pump (18); and / or The bottom of the desulfurization tower (1) is connected to a slurry discharge pipe equipped with a drainage pump (10).

4. The boiler flue gas wet desulfurization device according to claim 1, characterized in that: An in-tower flow equalization component (15) is installed below the slurry spray layer (16), and the in-tower flow equalization component is used to perform a secondary dispersion on the desulfurized slurry after the primary dispersion through the slurry spray layer (16); Preferably, a plurality of slurry spray layers (16) are provided, and the plurality of slurry spray layers (16) are arranged at intervals along the height direction of the desulfurization tower (1); more preferably, the number of the slurry spray layers (16) is 2-5; and / or Preferably, each of the slurry spray layers comprises at least one liquid distributor; and / or Preferably, the flow distribution component in the tower comprises a tower plate with a plurality of distribution holes.

5. The boiler flue gas wet desulfurization device according to claim 1, characterized in that: A demisting layer (17) is provided between the tail gas outlet (14) and the slurry spraying layer; Preferably, the demisting layer (17) is provided with multiple layers, and the multiple layers of the demisting layer (17) are arranged at intervals along the height direction; and / or Preferably, the demisting layer (17) is provided with 2-3 layers; and / or Preferably, a demister is installed in the demister layer (17).

6. A method for wet desulfurization of boiler flue gas, characterized in that: The method adopts the boiler flue gas wet desulfurization device according to any one of claims 1 to 5, comprising the following: Boiler hot flue gas is fed into the desulfurization tower (1) through the boiler flue gas inlet (14), and desulfurization slurry is sprayed downward through the slurry spray layer (16), and countercurrently contacts with the upward boiler hot flue gas, and after desulfurization and heat and mass exchange, upward tail gas and downward sulfur-containing slurry are formed, and the tail gas is discharged from the tail gas outlet (14), and the sulfur-containing slurry flows into the desulfurization slurry pool (12), and the heat in the desulfurization slurry pool (12) is recovered by the heat recovery component.

7. The method according to claim 6, wherein: The sulfur-containing slurry in the desulfurization slurry pool (12) is transported to the slurry spraying layer through the desulfurization slurry circulation pipe (13) to realize the recycling of the slurry; and / or The desulfurization slurry is selected from a sodium hydroxide aqueous solution and / or a sodium carbonate aqueous solution, preferably a sodium carbonate aqueous solution, and more preferably the desulfurization slurry is a 15-25wt% sodium carbonate aqueous solution; and / or The composition of the boiler flue gas includes N2, CO2, O2, SO2 and NO x At least one of .

8. The method according to claim 6 or 7, wherein: The pH of the slurry in the desulfurized slurry tank (12) is 5.5-7.0, preferably 6.0-6.3; and / or The density of the slurry in the desulfurization slurry tank (12) is 1.05-1.18 g / cm 3 .

9. The method according to any one of claims 6 to 8, wherein: When the pH of the slurry is lower than 5.5, 15-25 wt% sodium carbonate aqueous solution is fed through the desulfurizing agent feeding pipeline.

10. The method according to any one of claims 6 to 9, wherein: When the slurry density is greater than 1.18 g / cm 3 When the slurry is discharged from the desulfurization tower (1) through the slurry discharge pipe.

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