Ammonia desulfurization device for high-sulfur flue gas and ammonia desulfurization method for high-sulfur flue gas

Abstract

The invention relates to an ammonia desulfurization device and method for high-sulfur flue gas, and relates to the field of flue gas desulfurization, the ammonia desulfurization device comprises a flue gas cooling and humidifying section, a first desulfurization device and a second desulfurization device which are connected in sequence; the first desulfurization equipment is provided with an absorption liquid tank; the second desulfurization equipment is provided with an oxidation liquid tank and a washing liquid tank; the first desulfurization equipment comprises a first concentration section, a first spraying section, a first gas rising cap section, a first absorption section, a first at least three-stage spraying section and a first demisting section which are sequentially arranged from bottom to top; the second desulfurization equipment comprises a second absorption section, a second at least three-stage spraying section, a second gas rising cap section, a third absorption section, a second spraying section, a second demisting section, a third gas rising cap section, a fourth absorption section, a filler section, a third spraying section and a third demisting section which are arranged in sequence from bottom to top. According to the device provided by the invention, the temperature of the flue gas entering the tower is reduced and the humidity is controlled by virtue of the cooling and humidifying section, and the flue gas desulfurization effect is improved by adopting multi-stage desulfurization equipment.

Description

Technical Field

[0001] The invention relates to the field of flue gas desulfurization, and in particular to an ammonia desulfurization device for high-sulfur flue gas and an ammonia desulfurization method for high-sulfur flue gas. Background Art

[0002] At present, wet desulfurization and dry desulfurization are usually used to remove sulfur from high-temperature and high-sulfur flue gas generated by incineration. Common processes for wet desulfurization include: limestone / gypsum method and ammonia absorption method.

[0003] For example, CN109692551A discloses a calcium-based flue gas desulfurization method, which includes conveying a calcium-based absorbent and water to a mixing zone in the middle of the flue gas desulfurization device through a feeding mechanism in the feed zone of the flue gas desulfurization device to prepare an absorption liquid. After the absorption liquid is stirred and mixed evenly, it is sprayed downward from the top of the desulfurization zone of the flue gas desulfurization device, and the desulfurization treatment is completed after gas-liquid countercurrent contact with the flue gas entering from the bottom of the desulfurization zone. The calcium-based absorption liquid obtained at the bottom of the desulfurization zone is collected and conveyed to an oxidation pond for oxidation treatment. After static precipitation, gypsum by-product for industrial use is obtained at the bottom of the oxidation pond. The supernatant obtained on the upper layer of the oxidation pond is partially returned to the flue gas desulfurization device for recycling to prepare the absorption liquid.

[0004] CN112844023A discloses a flue gas ammonia wet desulfurization device, comprising a reactor, a filter box is fixedly installed on one side of the reactor, a stirring box is fixedly installed on one side of the reactor, a discharge box is fixedly installed on one side of the top of the stirring box, a water pump is fixedly installed on one side of the stirring box, a spray assembly is fixedly installed on the output end of the water pump, a water pump is fixedly installed on the bottom end of the reactor, and a reflux pipe is fixedly installed on the output end of the water pump.

[0005] Currently, ammonia-based desulfurization can effectively solve the problem of desulfurization efficiency due to its high activity and fast reaction rate. At the same time, the by-product of ammonium sulfate fertilizer can effectively reduce operating costs. However, in the desulfurization process of high-sulfur flue gas, there are difficulties such as high flue gas temperature, large reaction heat, high equilibrium temperature, and difficulty in controlling aerosol and ammonia escape, which lead to poor desulfurization effect. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide an ammonia desulfurization device for high-sulfur flue gas and an ammonia desulfurization method for high-sulfur flue gas, so as to solve the defects of poor desulfurization effect caused by the high flue gas temperature, large reaction heat, high equilibrium temperature, and difficult to control aerosol and ammonia escape in the desulfurization process of high-sulfur flue gas.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an ammonia-based desulfurization device for high-sulfur flue gas, the ammonia-based desulfurization device for high-sulfur flue gas comprising:

[0009] Connect the flue gas cooling and humidifying section, the first desulfurization equipment and the second desulfurization equipment in sequence;

[0010] The first desulfurization equipment is equipped with an absorption liquid tank;

[0011] The second desulfurization equipment is equipped with an oxidation liquid tank and a washing liquid tank;

[0012] The first desulfurization equipment includes, from bottom to top, a first concentration section, a first spray section, a first gas lift section, a first absorption section, a first at least three-stage spray section and a first demisting section, which are arranged in sequence;

[0013] The second desulfurization equipment includes, from bottom to top, a second absorption section, a second at least three-stage spray section, a second gas cap section, a third absorption section, a second spray section, a second demisting section, a third gas cap section, a fourth absorption section, a packing section, a third spray section and a third demisting section.

[0014] The ammonia desulfurization device for high-sulfur flue gas provided by the present invention reduces the temperature of the flue gas entering the tower and controls the humidity by means of the flue gas cooling and humidifying section through the design of the desulfurization device, thereby ensuring that the flue gas enters the desulfurization equipment within a reasonable temperature range. At the same time, multi-stage desulfurization equipment is used in coordination, and multi-stage absorption is adopted to control the oxidation rate and pH value of the absorption liquid in each layer, so as to control the reaction rate and reaction heat and then control the flue gas equilibrium temperature, thereby achieving an improvement in the flue gas desulfurization effect.

[0015] As a preferred technical solution of the present invention, the flue gas cooling and humidifying section is equipped with a first fan.

[0016] Preferably, the gas outlet of the first desulfurization equipment is connected to the second absorption section.

[0017] Preferably, the first concentration section is connected to the flue gas cooling and humidification section via a first pump and a cooler.

[0018] Preferably, the first concentration section is connected to the first spraying section via a first pump and a cooler.

[0019] As a preferred technical solution of the present invention, the first absorption section is connected to the absorption liquid tank.

[0020] Preferably, the absorption liquid tank is connected to the first at least three-stage spraying section via a second pump.

[0021] Preferably, the liquid phase inlet of the second pump is connected to the absorption liquid tank and the oxidation liquid tank respectively.

[0022] Preferably, the oxidation liquid tank is connected to the second absorption stage.

[0023] Preferably, the oxidation liquid tank is connected to the second at least three-stage spraying section via a third pump.

[0024] Preferably, the liquid phase inlet of the third pump is connected to the bottom slurry tank and the oxidation liquid tank of the second desulfurization equipment respectively.

[0025] Preferably, the oxidation liquid tank is connected to the second spraying section via a fourth pump.

[0026] As a preferred technical solution of the present invention, the washing liquid tank is connected to the fourth absorption stage.

[0027] Preferably, the washing liquid tank is connected to the third spray section via a fifth pump.

[0028] Preferably, the flue gas outlet of the second desulfurization equipment is connected to the flue gas inlet of the flue gas cooling and humidifying section through a branch line via a second fan.

[0029] Preferably, the absorption liquid tank is connected to the ammonium sulfate treatment end via a sixth pump.

[0030] In a second aspect, the present invention provides an ammonia desulfurization method for high-sulfur flue gas, which comprises: subjecting the flue gas to cooling and humidifying, concentration and washing, first absorption, second absorption, third absorption and washing purification in sequence to obtain purified flue gas.

[0031] As a preferred technical solution of the present invention, the temperature of the flue gas is ≥180°C, the humidity is ≥10%, and the sulfur content is ≥15000mg / Nm 3 .

[0032] As a preferred technical solution of the present invention, the temperature of the flue gas obtained after cooling and humidifying is less than 180°C.

[0033] As a preferred technical solution of the present invention, the concentrated washing medium includes an ammonium sulfate solution with a mass concentration of ≤40%.

[0034] Preferably, the washing process of the concentrated washing includes countercurrent contact between the flue gas and the medium.

[0035] Preferably, the liquid-to-gas ratio L / Nm during the concentrated washing process is 3 ≥2:1.

[0036] Preferably, the temperature of the flue gas obtained by the concentrated scrubbing is less than 55°C.

[0037] Preferably, the humidity of the flue gas obtained by the concentrated scrubbing reaches saturation.

[0038] As a preferred technical solution of the present invention, the oxidation rate of the absorption liquid used in the first absorption gradually decreases along the flow direction of the flue gas.

[0039] Preferably, the mass concentration of ammonium sulfate in the absorption liquid used in the first absorption is 95-99%.

[0040] Preferably, the liquid-to-gas ratio of the absorption liquid and the flue gas in the first absorption is L / Nm 3 ≥15:1.

[0041] Preferably, the oxidation rate of the absorption liquid used in the second absorption gradually decreases along the flow direction of the flue gas.

[0042] Preferably, the mass concentration of ammonium sulfate in the absorption liquid used in the second absorption is 90-97%.

[0043] Preferably, the liquid-to-gas ratio of the absorption liquid and the flue gas in the second absorption is L / Nm 3 ≥15:1.

[0044] As a preferred technical solution of the present invention, the mass concentration of ammonium sulfate in the absorption liquid used in the third absorption is ≥99%.

[0045] Preferably, the liquid-to-gas ratio of the absorption liquid and the flue gas in the third absorption is L / Nm 3 ≥5:1.

[0046] Preferably, the washing medium used in the washing purification comprises water.

[0047] Preferably, the liquid-to-gas ratio of the scrubbing medium and the flue gas in the third absorption is L / Nm 3 ≥5:1.

[0048] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0049] (1) The desulfurization process provided by the present invention is aimed at the characteristics of high temperature, high humidity and high sulfur of the flue gas after the incineration of acid gas. Air and / or clean flue gas at the outlet of the desulfurization tower are mixed into the inlet flue of the desulfurization equipment to reduce the temperature and humidity of the flue gas and the reaction equilibrium temperature, thereby preventing the decomposition of ammonium sulfite produced by the absorption reaction from the source and reducing the generation of aerosols.

[0050] (2) A pre-wash cooling section is set at the entrance of the desulfurization equipment to control the temperature of the flue gas entering the tower and protect the corrosion and internal parts of the tower.

[0051] (3) The desulfurization tower is divided into zones by installing partitions and air lift caps. Each zone cooperates with each other. The flue gas is cooled, sulfur dioxide is removed, washed, purified, and demisted in turn. At the same time, due to the extremely high sulfur content in the flue gas, the desulfurization reaction releases a large amount of heat. The sulfur dioxide absorption is controlled in stages and grades to control the reaction rate, prevent ammonia escape and aerosol generation, and ensure that the emission meets the standards. The sulfur dioxide content in the flue gas after purification is ≤29mg / Nm 3, particle content ≤4.3mg / Nm 3 , ammonia escape ≤2.4mg / Nm 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of an ammonia-based desulfurization device for high-sulfur flue gas provided in an embodiment of the present invention.

[0053] In the figure: 1-first fan, 2-smoke cooling and humidifying section, 3-first concentration section, 4-first spray section, 5-first gas cap section, 6-first absorption section, 7-first at least three-stage spray section, 8-first demisting section, 9-flue, 10-second absorption section, 11-second at least three-stage spray section, 12-second gas cap section, 13-third absorption section, 14-second spray section, 15-second demisting section, 16-third gas cap section, 17-fourth absorption section, 18-filling section, 19-third spray section, 20-third demisting section, 21-second fan, 22-sixth pump, 23-first pump, 24-cooler, 25-absorption liquid tank, 26-second pump, 27-third pump, 28-oxidation liquid tank, 29-fourth pump, 30-oxidation fan, 31-washing liquid tank, 32-fifth pump;

[0054] I-flue gas, II-purified flue gas, III-ammonium sulfate treatment end.

[0055] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0056] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0057] This embodiment provides an ammonia desulfurization device for high-sulfur flue gas, such as Figure 1 As shown, the ammonia desulfurization device for high-sulfur flue gas comprises:

[0058] Connect the flue gas cooling and humidifying section 2, the first desulfurization equipment and the second desulfurization equipment in sequence;

[0059] The first desulfurization equipment is equipped with an absorption liquid tank 25;

[0060] The second desulfurization equipment is equipped with an oxidation liquid tank 28 and a washing liquid tank 31;

[0061] The first desulfurization equipment includes, from bottom to top, a first concentration section 3, a first spray section 4, a first gas lift section 5, a first absorption section 6, a first at least three-stage spray section 7 and a first demisting section 8, which are arranged in sequence;

[0062] The second desulfurization equipment includes, from bottom to top, a second absorption section 10, a second at least three-stage spray section 11, a second gas lift cap section 12, a third absorption section 13, a second spray section 14, a second demisting section 15, a third gas lift cap section 16, a fourth absorption section 17, a packing section 18, a third spray section 19 and a third demisting section 20, which are arranged in sequence.

[0063] Specifically, the flue gas I cooling and humidifying section 2 is equipped with a first fan 1.

[0064] Specifically, the gas outlet of the first desulfurization equipment is connected to the second absorption section 10 .

[0065] Specifically, the first concentration section 3 is connected to the flue gas cooling and humidification section 2 through a first pump 23 and a cooler 24 .

[0066] Specifically, the first concentration section 3 is connected to the first spraying section 4 through a first pump 23 and a cooler 24 .

[0067] Specifically, the first absorption section 6 is connected to the absorption liquid tank 25 .

[0068] Specifically, the absorption liquid tank 25 is connected to the first at least three-stage spraying section 7 via a second pump 26 .

[0069] Specifically, the liquid phase inlet of the second pump 26 is connected to the absorption liquid tank 25 and the oxidation liquid tank 28 respectively.

[0070] Specifically, the oxidation liquid tank 28 is connected to the second absorption stage 10 .

[0071] Specifically, the oxidation liquid tank 28 is connected to the second at least three-stage spraying section 11 through the third pump 27 .

[0072] Specifically, the liquid phase inlet of the third pump 27 is connected to the bottom slurry tank and the oxidation liquid tank 28 of the second desulfurization equipment respectively;

[0073] Specifically, the oxidation liquid tank 28 is connected to the second spraying section 14 via a fourth pump 29 .

[0074] Specifically, the washing liquid tank 31 is connected to the fourth absorption stage 17 .

[0075] Specifically, the washing liquid tank 31 is connected to the third spray section 19 via a fifth pump 32 .

[0076] Specifically, the flue gas outlet of the second desulfurization equipment is connected to the flue gas inlet of the flue gas cooling and humidifying section 2 through a branch through the second fan 21 .

[0077] Specifically, the absorption liquid tank 25 is connected to the ammonium sulfate treatment end III through the sixth pump 22 .

[0078] In the present invention, the oxidation liquid tank 28 may be supplied with an oxidizing medium via an oxidation blower 30 .

[0079] An exemplary processing procedure is as follows:

[0080] The high-temperature, high-humidity and high-sulfur flue gas I generated by incineration is transported to the flue gas cooling and humidification section 2. In the flue gas cooling and humidification section 2, the flue gas I is first mixed with the air sent by the blower and / or the purified flue gas II obtained from the flue gas outlet of the second desulfurization equipment, and then sent to the first desulfurization equipment for cooling and humidification after preliminary cooling and dehumidification, ensuring that the flue gas temperature entering the tower is controlled below 180°C to prevent the anti-corrosion and internal parts in the tower from being damaged due to high temperature.

[0081] The flue gas after cooling and humidification is sent to the middle and lower concentration section of the desulfurization tower for concentration and washing. The flue gas is cooled and washed again with the cooled ammonium sulfate solution. At this time, the flue gas temperature drops to below 55°C. The cooling and washing liquid in the concentration section uses ammonium sulfate solution. After cooling with circulating cooling water, it is sprayed out from the spray layer in the tower and countercurrently contacts with the flue gas to fully wash and cool it. At the same time, the ammonium sulfate solution countercurrently contacts with the high-temperature flue gas, and the water is evaporated and further concentrated. It is transported to the ammonium sulfate processing end III by the discharge pump to produce commercial ammonium sulfate. The flue gas after washing and cooling enters the middle absorption section of the first desulfurization equipment through the gas lifting cap in the tower.

[0082] Due to the extremely high sulfur content in flue gas, in order to prevent the violent absorption reaction from causing a large amount of heat release, the absorption stage adopts three-stage absorption:

[0083] First absorption: adopt an independent circulation system, configure an absorption liquid tank 25, set up multiple layers of absorption liquid spray layers in the tower, and the absorption liquid in the spray layer is provided by a circulation pump. The oxidation rate of the absorption liquid sprayed from the multiple layers of spray layers in the tower gradually increases and decreases from bottom to top, so as to control the absorption reaction rate, minimize the concentrated reaction heat release, and prevent the absorption reaction from releasing a large amount of heat so that the droplet temperature is too high, causing the ammonium sulfite generated by the reaction to decompose due to heat, thereby forming an aerosol. The control of the oxidation rate is achieved by setting the opening angle of the valve at the pump inlet to adjust the amount of liquid extracted from the absorption circulation tank and the oxidation circulation tank by the absorption circulation pump, as well as the pH meter and oxidation rate analyzer at the pump outlet. After the first absorption, the sulfur dioxide concentration in the flue gas is reduced by about 50%, and the flue gas is sent to the second desulfurization equipment through the flue 9 after pre-demisting for the second absorption and the third absorption;

[0084] Second absorption: The main configuration is the same as the first absorption. After the sulfur dioxide in the flue gas is removed to the control requirement, it goes up to the third absorption through the gas lifting cap in the tower;

[0085] The third absorption: adopts an independent circulation system, equipped with an oxidation circulation tank. The absorption liquid (mainly ammonium sulfite) sent from the first and second absorptions is fully oxidized into ammonium sulfate solution by multiple layers of evenly distributed oxidation air in the oxidation circulation tank, and the oxidation rate is over 99%. A spray layer is set in the tower. The spray liquid uses ammonium sulfate solution with an oxidation rate of over 99%. The flue gas is washed again to remove aerosols, ammonia and other substances entrained in the flue gas. A demister is set on the top of the spray layer. At the same time, the oxidation liquid in the oxidation tank is exchanged with the first and second absorption liquids. On the one hand, the absorption liquid is oxidized and sent to the concentration section. On the other hand, the oxidation liquid is added to control the oxidation rate of the absorption liquid in each layer to achieve step absorption.

[0086] After sulfur dioxide is fully removed from the flue gas, it enters the water washing purification section. Under the purification effect of the water washing circulating liquid, the salt content of the droplets entrained in the flue gas is further reduced, and the water washing circulating liquid flows back to the washing liquid tank 31 through the reflux pipe.

[0087] In the absorption section, the flue gas is fully contacted with the absorption liquid through multi-stage spraying to remove SO 2 , and then enters the demisting section at the top of the tower, where it is discharged into the atmosphere after the mist entrained in the flue gas is removed by the "combined demisting device".

[0088] Furthermore, the present invention provides a method for desulfurization of high-sulfur flue gas using ammonia, the method comprising:

[0089] The flue gas is subjected to cooling and humidification, concentration and washing, first absorption, second absorption, third absorption and washing purification in sequence to obtain purified flue gas.

[0090] The temperature of the flue gas is ≥180°C, the humidity is ≥10%, and the sulfur content is ≥15000mg / Nm 3 .

[0091] Among them, the temperature of the flue gas obtained after cooling and humidifying is <180°C, for example, it can be 175°C, 170°C, 165°C, 160°C, 155°C, 150°C, 140°C, 130°C or 120°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0092] The concentrated washing medium comprises an ammonium sulfate solution with a mass concentration of ≤40%, for example, 40%, 35%, 30%, 25%, 20%, 15%, 10% or 5%, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0093] The washing process of the concentrated washing includes countercurrent contact between the flue gas and the medium.

[0094] Among them, the liquid-gas ratio L / Nm during the washing process of the concentrated washing is 3≥2:1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1 or 7:1, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0095] The temperature of the flue gas obtained by the concentrated washing is <55°C, for example, it can be 50°C, 45°C, 40°C, 35°C, 30°C, 25°C or 20°C, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0096] The humidity of the flue gas obtained by the concentrated washing reaches saturation.

[0097] Among them, the oxidation rate of the absorption liquid used in the first absorption gradually decreases along the flow direction of the flue gas.

[0098] Among them, the mass concentration of ammonium sulfate in the absorption liquid used in the first absorption is 95-99%, for example, it can be 95%, 96%, 97%, 98% or 99%, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0099] In the present invention, the reduction in the oxidation rate of the absorption liquid refers to the reduction in the concentration of ammonium sulfate in the absorption liquid, that is, the mass concentration of ammonium sulfate in the absorption liquid used along the flow direction of the flue gas in the first absorption gradually decreases. The design can be made based on the absorption stage and the range of the mass concentration of ammonium sulfate. For example, in the case of three-stage spray absorption, the mass concentration of ammonium sulfate along the flow direction of the flue gas is 97-98%, 96-97%, and 95-96%.

[0100] Among them, the liquid-to-gas ratio of the absorption liquid and the flue gas in the first absorption is L / Nm 3 ≥15:1, for example, it can be 15:1, 16:1, 17:1, 18:1, 19:1 or 20:1, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0101] Among them, the oxidation rate of the absorption liquid used in the second absorption gradually decreases along the flow direction of the flue gas.

[0102] Among them, the mass concentration of ammonium sulfate in the absorption liquid used in the second absorption is 90-97%, for example, it can be 90%, 91%, 92%, 93%, 94%, 95%, 96% or 97%, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0103] In the present invention, the reduction in the oxidation rate of the absorption liquid refers to the reduction in the concentration of ammonium sulfate in the absorption liquid, that is, the mass concentration of ammonium sulfate in the absorption liquid used along the flow direction of the flue gas in the second absorption gradually decreases. The design can be made based on the absorption stage and the range of the mass concentration of ammonium sulfate. For example, in the case of three-stage spray absorption, the mass concentration of ammonium sulfate along the flow direction of the flue gas is 95-97%, 93-94%, and 90-92%.

[0104] Among them, the liquid-to-gas ratio of the absorption liquid and the flue gas in the second absorption is L / Nm 3 ≥15:1, for example, it can be 15:1, 16:1, 17:1, 18:1, 19:1 or 20:1, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0105] Among them, the mass concentration of ammonium sulfate in the absorption liquid used in the third absorption is ≥99%, for example, it can be 99%, 99.2%, 99.4%, 99.6% or 99.8%, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0106] Among them, the liquid-to-gas ratio of the absorption liquid and the flue gas in the third absorption is L / Nm 3 ≥5:1, for example, it can be 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0107] Wherein, the washing medium used in the washing and purification includes water.

[0108] Among them, the liquid-gas ratio of the scrubbing medium and the flue gas in the third absorption is L / Nm 3 ≥5:1, for example, it can be 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0109] Further, in order to illustrate the good desulfurization effect that can be achieved by the ammonia desulfurization device for high-sulfur flue gas provided by the present invention, an actual example is used for exemplary description, as follows:

[0110] Example 1

[0111] This embodiment provides an ammonia desulfurization process for high-sulfur flue gas, which is as follows:

[0112] The temperature of the high sulfur flue gas used was 240°C, the humidity was 18%, and the sulfur content was 30000mg / Nm 3 ;

[0113] The high-sulfur flue gas is subjected to cooling and humidification, concentration and washing, first absorption, second absorption, third absorption and washing purification in sequence to obtain purified flue gas.

[0114] The temperature of the flue gas obtained after cooling and humidification is 120°C;

[0115] The concentrated washing medium is an ammonium sulfate solution with a mass concentration of 30%; the washing process of the concentrated washing includes countercurrent contact between the flue gas and the medium; the liquid-gas ratio L / Nm in the washing process of the concentrated washing is 3 ≥3.7:1; the temperature of the flue gas obtained by the concentrated washing is 45°C; the humidity of the flue gas obtained by the concentrated washing reaches saturation;

[0116] The oxidation rate of the absorption liquid used in the first absorption along the flow direction of the flue gas gradually decreases. The mass concentration of ammonium sulfate in the absorption liquid used in the first absorption is 95%, 97%, and 99%. The concentration of ammonium sulfate in the absorption liquid used along the flow direction of the flue gas gradually decreases, that is, a three-stage absorption spray is performed; the liquid-to-gas ratio of the absorption liquid and the flue gas in the first absorption is L / Nm 3 is 21:1;

[0117] The mass concentration of ammonium sulfate in the absorption liquid used in the second absorption is 90%, 92%, and 95%, and the ammonium sulfate concentration of the absorption liquid used along the flow direction of the flue gas gradually decreases, that is, a three-stage absorption spray is performed; the liquid-to-gas ratio of the absorption liquid and the flue gas in the second absorption is L / Nm 3 is 21:1;

[0118] The mass concentration of ammonium sulfate in the absorption liquid used in the third absorption is 99%, and the liquid-to-gas ratio of the absorption liquid and the flue gas in the third absorption is L / Nm 3 is 7:1;

[0119] The washing medium used in the washing purification is water; the liquid-gas ratio of the washing medium and the flue gas in the third absorption is L / Nm 3 ≥7:1.

[0120] The obtained flue gas indicators after purification are shown in Table 1.

[0121] Example 2

[0122] This embodiment provides an ammonia desulfurization process for high-sulfur flue gas, which is as follows:

[0123] The temperature of the high sulfur flue gas used was 240°C, the humidity was 12%, and the sulfur content was 18000 mg / Nm 3 ;

[0124] The high-sulfur flue gas is subjected to cooling and humidification, concentration and washing, first absorption, second absorption, third absorption and washing purification in sequence to obtain purified flue gas.

[0125] The temperature of the flue gas obtained after cooling and humidification is 150°C;

[0126] The concentrated washing medium includes an ammonium sulfate solution with a mass concentration of 25%; the washing process of the concentrated washing includes countercurrent contact between the flue gas and the medium; the liquid-gas ratio L / Nm in the washing process of the concentrated washing is 3 is 2.8:1; the temperature of the flue gas obtained by the concentrated washing is 35°C; the humidity of the flue gas obtained by the concentrated washing reaches saturation;

[0127] The oxidation rate of the absorption liquid used in the first absorption along the flow direction of the flue gas gradually decreases. The mass concentration of ammonium sulfate in the absorption liquid used in the first absorption is 96%, 97%, and 98%. The concentration of ammonium sulfate in the absorption liquid used along the flow direction of the flue gas gradually decreases, that is, a three-stage absorption spray is performed; the liquid-to-gas ratio of the absorption liquid and the flue gas in the first absorption is L / Nm 3 is 17:1;

[0128] The mass concentration of ammonium sulfate in the absorption liquid used in the second absorption is 92%, 94%, and 96%, and the ammonium sulfate concentration of the absorption liquid used along the flow direction of the flue gas gradually decreases, that is, a three-stage absorption spray is performed; the liquid-to-gas ratio of the absorption liquid and the flue gas in the second absorption is L / Nm 3 is 17:1;

[0129] The mass concentration of ammonium sulfate in the absorption liquid used in the third absorption is 99.5%, and the liquid-to-gas ratio of the absorption liquid and the flue gas in the third absorption is L / Nm 3 5.5:1;

[0130] The washing medium used in the washing purification is water; the liquid-gas ratio of the washing medium and the flue gas in the third absorption is L / Nm 3 It is 6:1.

[0131] The obtained flue gas indicators after purification are shown in Table 1.

[0132] Example 3

[0133] This embodiment provides an ammonia desulfurization process for high-sulfur flue gas, which is as follows:

[0134] The temperature of the high sulfur flue gas used was 185°C, the humidity was 16%, and the sulfur content was 18000 mg / Nm 3 ;

[0135] The high-sulfur flue gas is subjected to cooling and humidification, concentration and washing, first absorption, second absorption, third absorption and washing purification in sequence to obtain purified flue gas.

[0136] The temperature of the flue gas obtained after the cooling and humidification is 100°C;

[0137] The concentrated washing medium includes an ammonium sulfate solution with a mass concentration of 28%; the concentrated washing process includes countercurrent contact between the flue gas and the medium; the liquid-gas ratio L / Nm in the concentrated washing process is 3 is 2.7:1; the temperature of the flue gas obtained by the concentrated washing is 25°C; the humidity of the flue gas obtained by the concentrated washing reaches saturation;

[0138] The oxidation rate of the absorption liquid used in the first absorption is gradually reduced along the flow direction of the flue gas; the mass concentration of ammonium sulfate in the absorption liquid used in the first absorption is 97%, 98%, and 99%, and the concentration of ammonium sulfate in the absorption liquid used in the flow direction of the flue gas is gradually reduced, that is, a three-stage absorption spray is performed; the liquid-to-gas ratio of the absorption liquid and the flue gas in the first absorption is L / Nm 3 is 19:1;

[0139] The mass concentration of ammonium sulfate in the absorption liquid used in the second absorption is 94%, 96%, and 97%, and the ammonium sulfate concentration of the absorption liquid used along the flow direction of the flue gas gradually decreases, that is, a three-stage absorption spray is performed; the liquid-to-gas ratio of the absorption liquid and the flue gas in the second absorption is L / Nm 3 is 19:1;

[0140] The mass concentration of ammonium sulfate in the absorption liquid used in the third absorption is 99.2%, and the liquid-to-gas ratio of the absorption liquid and the flue gas in the third absorption is L / Nm 3 is 6.5:1;

[0141] The washing medium used in the washing purification includes water; the liquid-gas ratio of the washing medium and the flue gas in the third absorption is L / Nm 3 It is 7:1.

[0142] The obtained flue gas indicators after purification are shown in Table 1.

[0143] Example 4

[0144] This embodiment provides an ammonia desulfurization process for high-sulfur flue gas, which is as follows:

[0145] The temperature of the high sulfur flue gas used was 185°C, the humidity was 13%, and the sulfur content was 33000 mg / Nm 3 ;

[0146] The high-sulfur flue gas is subjected to cooling and humidification, concentration and washing, first absorption, second absorption, third absorption and washing purification in sequence to obtain purified flue gas.

[0147] The temperature of the flue gas obtained after cooling and humidification is 80°C;

[0148] The concentrated washing medium includes an ammonium sulfate solution with a mass concentration of 32%; the concentrated washing process includes countercurrent contact between the flue gas and the medium; the liquid-gas ratio L / Nm in the concentrated washing process is 3 is 2.5:1; the temperature of the flue gas obtained by the concentrated washing is 45°C; the humidity of the flue gas obtained by the concentrated washing reaches saturation;

[0149] The oxidation rate of the absorption liquid used in the first absorption is gradually reduced along the flow direction of the flue gas; the mass concentration of ammonium sulfate in the absorption liquid used in the first absorption is 96%, 98%, and 99%, and the concentration of ammonium sulfate in the absorption liquid used in the flow direction of the flue gas is gradually reduced, that is, a three-stage absorption spray is performed; the liquid-to-gas ratio of the absorption liquid and the flue gas in the first absorption is L / Nm 3 is 20:1;

[0150] The mass concentration of ammonium sulfate in the absorption liquid used in the second absorption is 92%, 95%, and 97%, and the ammonium sulfate concentration of the absorption liquid used along the flow direction of the flue gas gradually decreases, that is, a three-stage absorption spray is performed; the liquid-to-gas ratio of the absorption liquid and the flue gas in the second absorption is L / Nm 3 is 20:1;

[0151] The mass concentration of ammonium sulfate in the absorption liquid used in the third absorption is 99.8%, and the liquid-to-gas ratio of the absorption liquid and the flue gas in the third absorption is L / Nm 3 is 7:1;

[0152] The washing medium used in the washing purification includes water; the liquid-gas ratio of the washing medium and the flue gas in the third absorption is L / Nm 3 It is 7:1.

[0153] The obtained flue gas indicators after purification are shown in Table 1.

[0154] Table 1

[0155]

[0156]

[0157] As can be seen from Table 1, in the scheme provided by the present invention, effective measures such as flue gas cooling and humidification, the use of multi-stage desulfurization equipment, and multi-stage absorption in the tower are used to control the oxidation rate and pH value of each layer of absorption liquid, so as to control the reaction rate and reaction heat and then control the flue gas equilibrium temperature, thereby achieving an improvement in the desulfurization effect of high-temperature, high-humidity, and high-sulfur flue gas, and effectively inhibiting the generation of aerosols and ammonia escape, ensuring that pollutants can be discharged in compliance with standards.

[0158] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0159] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0160] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An ammonia desulfurization device for high-sulfur flue gas, characterized in that: The ammonia desulfurization device for high-sulfur flue gas comprises: Connect the flue gas cooling and humidifying section, the first desulfurization equipment and the second desulfurization equipment in sequence; The first desulfurization equipment is equipped with an absorption liquid tank; The second desulfurization equipment is equipped with an oxidation liquid tank and a washing liquid tank; The first desulfurization equipment includes, from bottom to top, a first concentration section, a first spray section, a first gas lift section, a first absorption section, a first at least three-stage spray section and a first demisting section, which are arranged in sequence; The second desulfurization equipment includes, from bottom to top, a second absorption section, a second at least three-stage spray section, a second gas cap section, a third absorption section, a second spray section, a second demisting section, a third gas cap section, a fourth absorption section, a packing section, a third spray section and a third demisting section.

2. The ammonia desulfurization device for high-sulfur flue gas according to claim 1, characterized in that: The flue gas cooling and humidifying section is equipped with a first fan; Preferably, the gas outlet of the first desulfurization equipment is connected to the second absorption section; Preferably, the first concentration section is connected to the flue gas cooling and humidification section via a first pump and a cooler; Preferably, the first concentration section is connected to the first spraying section via a first pump and a cooler.

3. The ammonia desulfurization device for high-sulfur flue gas according to claim 1 or 2, characterized in that: The first absorption section is connected to the absorption liquid tank; Preferably, the absorption liquid tank is connected to the first at least three-stage spraying section via a second pump; Preferably, the liquid phase inlet of the second pump is connected to the absorption liquid tank and the oxidation liquid tank respectively; Preferably, the oxidation liquid tank is connected to the second absorption stage; Preferably, the oxidation liquid tank is connected to the second at least three-stage spraying section via a third pump; Preferably, the liquid phase inlet of the third pump is connected to the bottom slurry tank and the oxidation liquid tank of the second desulfurization equipment respectively; Preferably, the oxidation liquid tank is connected to the second spraying section via a fourth pump.

4. The ammonia desulfurization device for high-sulfur flue gas according to any one of claims 1 to 3, characterized in that: The washing liquid tank is connected to the fourth absorption stage; Preferably, the washing liquid tank is connected to the third spray section via a fifth pump; Preferably, the flue gas outlet of the second desulfurization equipment is connected to the flue gas inlet of the flue gas cooling and humidifying section through a branch line through a second fan; Preferably, the absorption liquid tank is connected to the ammonium sulfate treatment end via a sixth pump.

5. A method for desulfurization of high-sulfur flue gas by ammonia method, characterized in that: The ammonia desulfurization method for high-sulfur flue gas comprises: The flue gas is subjected to cooling and humidification, concentration and washing, first absorption, second absorption, third absorption and washing purification in sequence to obtain purified flue gas.

6. The method for desulfurization of high-sulfur flue gas by ammonia method according to claim 5, characterized in that: The temperature of the flue gas is ≥180°C, the humidity is ≥10%, and the sulfur content is ≥15000mg / Nm 3 .

7. The method for desulfurization of high-sulfur flue gas by ammonia method according to claim 5 or 6, characterized in that: The temperature of the flue gas obtained after the cooling and humidification is less than 180°C.

8. The method for desulfurization of high-sulfur flue gas by ammonia method according to any one of claims 5 to 7, characterized in that: The concentrated washing medium includes an ammonium sulfate solution with a mass concentration of ≤40%; Preferably, the washing process of the concentrated washing includes countercurrent contact between the flue gas and the medium; Preferably, the liquid-to-gas ratio L / Nm during the concentrated washing process is 3 ≥2:1; Preferably, the temperature of the flue gas obtained by the concentrated scrubbing is <55°C; Preferably, the humidity of the flue gas obtained by the concentrated scrubbing reaches saturation.

9. The method for desulfurization of high-sulfur flue gas by ammonia method according to any one of claims 5 to 8, characterized in that: The oxidation rate of the absorption liquid used in the first absorption gradually decreases along the flow direction of the flue gas; Preferably, the mass concentration of ammonium sulfate in the absorption liquid used in the first absorption is 95-99%; Preferably, the liquid-to-gas ratio of the absorption liquid and the flue gas in the first absorption is L / Nm 3 ≥15:1; Preferably, the oxidation rate of the absorption liquid used in the second absorption gradually decreases along the flow direction of the flue gas; Preferably, the mass concentration of ammonium sulfate in the absorption liquid used in the second absorption is 90-97%; Preferably, the liquid-to-gas ratio of the absorption liquid and the flue gas in the second absorption is L / Nm 3 ≥15:

1.

10. The method for desulfurization of high-sulfur flue gas by ammonia method according to any one of claims 5 to 9, characterized in that: The mass concentration of ammonium sulfate in the absorption liquid used in the third absorption is ≥99%; Preferably, the liquid-to-gas ratio of the absorption liquid and the flue gas in the third absorption is L / Nm 3 ≥5:1; Preferably, the washing medium used in the washing and purification comprises water; Preferably, the liquid-to-gas ratio of the scrubbing medium and the flue gas in the third absorption is L / Nm 3 ≥5:1.

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