Device for decarburization and comprehensive utilization of flue gas by ammonia process

Abstract

The utility model discloses a device for decarburization and comprehensive utilization of flue gas by an ammonia process. The device comprises an absorption tower with a flue gas inlet pipe and a flue gas outlet, an absorption liquid tank, a spraying layer group for spraying absorption liquid into the absorption tower, a combined demister for demisting in the absorption tower, and a cooling device, the lower part of the absorption tower is filled with absorption liquid; the cooling device is used for cooling flue gas in the flue gas inlet pipe, and the flue gas inlet pipe is provided with a condensate water discharge pipe. The device has the advantages that the pH of the absorption liquid is controlled through the two-section or multi-section absorption tower, so that the ammonia escape is reduced, and the carbon dioxide absorption rate is improved; two process routes are arranged to solve the problems of imbalanced carbon and nitrogen in the absorption liquid and overhigh operation cost; high-temperature flue gas waste heat before desulfurization is used as a heat source in the analysis device to reduce energy consumption.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas decarbonization, in particular to a device for flue gas decarbonization and comprehensive utilization using an ammonia process. Background Art

[0002] At present, chemical absorption is the technology with the most promising commercial application in industrial CO2 capture technology. It mainly uses alkaline absorbents to react chemically with CO2 in industrial flue gas to achieve CO2 capture. Commonly used chemical absorbents include organic amine solutions, potassium carbonate solutions, ammonia solutions and strong alkali solutions. Among them, organic amine solutions represented by MEA are the most common chemical absorbents used for CO2 capture. However, organic amine solutions have bottleneck problems such as high regeneration energy consumption, high corrosion to the system, large cycle degradation losses and high initial investment costs. Compared with the traditional MEA method, the inorganic ammonia method in the chemical absorption method has the characteristics of strong absorption capacity, low corrosiveness, low regeneration energy consumption, low replenishment cost, not easy to degrade, and can remove multiple acidic gas pollutants at the same time, which has attracted widespread attention and research.

[0003] Currently, there are two main directions after ammonia decarbonization: one is to directly produce ammonium bicarbonate fertilizer; the other is to heat and decompose the generated ammonium bicarbonate to produce CO2, but these two methods cannot solve the current problems of high decarbonization cost and unbalanced carbon-nitrogen ratio.

[0004] Patent announcement number CN114870599A discloses a device and method for producing ammonium bicarbonate in an ammonia decarbonization system. The device includes a cooling functional area, an ammonium bicarbonate generation area, a CO2 absorption area, and an ammonia removal functional area. By performing zoning control on ammonium bicarbonate generation, CO2 absorption, and ammonia removal, the decarbonization absorption efficiency is improved and ammonia escape is reduced. At the same time, the CO2 in the flue gas can be used to produce ammonium bicarbonate that can be used as a nitrogen fertilizer. However, in actual applications, since the concentration of CO2 in industrial flue gas is often relatively high, this method requires a large amount of ammonia solution for absorption, and the operating cost is high.

[0005] Patent announcement number CN218047279U provides a desorption tower and an ammonia decarbonization system. The desorption tower body is provided with a liquid storage area, a primary desorption area and a secondary desorption area from the bottom to the top. The desorption is carried out by splitting the rich liquid, recovering the heat of the top product gas and reducing the temperature of the process gas at the outlet of the regeneration tower. Accordingly, the semi-lean liquid and the lean liquid after the rich liquid is analyzed in the ammonia decarbonization system enter the absorption tower at different positions for graded absorption, thereby improving the absorption efficiency. Although the system recovers a certain amount of waste heat, desorption requires a large amount of heat.

[0006] From the above background, we know that although there are several ammonia decarbonization methods, all of them have problems to varying degrees. In order to solve these problems, a system and method for ammonia flue gas decarbonization and comprehensive utilization are proposed. Two or more absorption stages are used in a set of equipment to control the pH value of the absorption liquid to reduce the problem of ammonia escape, and two different routes are used to solve the problem of carbon-nitrogen imbalance in the rich liquid and flue gas after decarbonization. Utility Model Content

[0007] The technical problem to be solved by the utility model is to provide a device for decarbonizing and comprehensively utilizing flue gas using an ammonia method.

[0008] In order to solve the above technical problems, the technical solution of the utility model is:

[0009] An ammonia flue gas decarbonization and comprehensive utilization device comprises an absorption tower with a flue gas inlet pipe and a flue gas outlet, an absorption liquid tank, a spray layer group for spraying absorption liquid into the absorption tower, a combined demister for defogging in the absorption tower, and a cooling device; the lower part of the absorption tower is filled with absorption liquid; the cooling device is used for cooling the flue gas in the flue gas inlet pipe, and the flue gas inlet pipe is provided with a condensed water discharge pipe.

[0010] Preferably, it also includes an ammonium bicarbonate preparation device, which includes a rich liquid pump whose inlet is connected to the lower part of the absorption tower through a pipeline, a cooling crystallization tank connected to the outlet of the rich liquid pump through a pipeline, a heat exchanger used for heat exchange of the cooling crystallization tank, a refrigerator used to provide a cold source to the heat exchanger, an ammonium bicarbonate slurry pump whose inlet is connected to the lower part of the cooling crystallization tank through a pipeline, a hydrocyclone whose inlet is connected to the outlet of the ammonium bicarbonate slurry pump through a pipeline, a centrifuge connected to the lower discharge port of the hydrocyclone through a pipeline, a dryer used to dry the material at the discharge port of the centrifuge, an ammonium bicarbonate silo used to store the material discharged from the dryer, and a packaging machine used to pack the material in the ammonium bicarbonate silo.

[0011] Preferably, it also includes a carbon dioxide preparation device, which includes a rich liquid circulation tank whose upper part is connected to the outlet end of the rich liquid pump through a pipeline, a heat exchange device connected to the rich liquid circulation tank through a circulation pump, a gas-liquid separator connected to the top carbon dioxide mixed gas outlet of the heat exchange device, a carbon dioxide purification device whose inlet is connected to the exhaust port of the gas-liquid separator through a pipeline, a carbon dioxide compressor whose inlet is connected to the carbon dioxide gas outlet of the carbon dioxide purification device through a pipeline, and a carbon dioxide storage tank for storing carbon dioxide liquid discharged by the carbon dioxide compressor; the ammonia gas outlet of the carbon dioxide purification device is connected to the lower part of the absorption liquid tank through an ammonia pipeline;

[0012] The liquid discharge port of the centrifuge and the upper liquid discharge port of the hydrocyclone are respectively connected to the absorption liquid tank through pipelines.

[0013] Preferably, a drain pipe is provided on the rich liquid circulation tank, and the drain pipe is connected to the absorption liquid tank.

[0014] Preferably, the spray layer group includes a first spray layer and a second spray layer located above the first spray layer, the inlet of the first spray layer is connected to a first spray pump through a pipeline, and the inlet of the first spray pump is connected to the lower part of the absorption tower through a pipeline; the inlet of the second spray layer group is connected to a second spray pump through a pipeline, and the inlet of the second spray pump is connected to the lower part of the absorption liquid tank through a pipeline.

[0015] The above technical solution has the following advantages:

[0016] (1) The flue gas of the utility model enters a two-stage or multi-stage absorption tower after being cooled, thereby effectively preventing ammonia from escaping, increasing the power of gas-liquid transmission, and facilitating the absorption of carbon dioxide. The multi-stage spray tower absorption process can control the pH value of the absorption liquid in the multi-stage absorption tower, prevent ammonia from escaping, and ensure a high absorption rate of carbon dioxide, with the absorption rate of carbon dioxide exceeding 80%.

[0017] (2) The utility model adopts a hydrocyclone to process the crystal slurry after cooling and crystallization, separates the solid and liquid of the ammonium bicarbonate crystals, and then dries and packs them, which can be used in the production of ammonium bicarbonate fertilizers to achieve product diversification. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A simplified diagram of the system of the utility model;

[0019] In the figure, 1, flue gas inlet pipe; 2, cooling device; 3, absorption tower; 4, circulating liquid; 5, first spray layer; 6, second spray layer; 7, combined demister; 8, first spray pump; 9, second spray pump; 10, absorption liquid tank; 11, washing tank (used to recover the washing liquid of the combined demister and provide spray liquid for the combined demister); 12, refrigerator; 13, heat exchanger; 14, cooling crystallization tank; 15, ammonium bicarbonate slurry pump; 16, dryer; 17, ammonium bicarbonate material warehouse; 18. packaging machine; 19. centrifuge; 20. hydrocyclone; 21. rich liquid circulation tank; 22. return pipe; 23. discharge pipe; 24. ammonia pipeline; 25. carbon dioxide purification device; 26. carbon dioxide compressor; 27. carbon dioxide storage tank; 28. gas-liquid separator; 29. ​​heat exchange device; 30. flue gas outlet; 31. desalted water; 32. condensate discharge pipe; 33. rich liquid pump; 34. flue gas after heat exchange; 35. high-temperature flue gas before desulfurization; 36. circulation pump. DETAILED DESCRIPTION

[0020] The specific implementation methods of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these implementation methods is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each implementation method of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] As attached Figure 1 As shown, an ammonia flue gas decarbonization and comprehensive utilization device includes an absorption tower 3 with a flue gas inlet pipe 1 and a flue gas outlet 30, an absorption liquid tank 10, a spray layer group for spraying absorption liquid into the absorption tower 3, a combined demister 7 for demisting the absorption tower 3, and a cooling device 2; the lower part of the absorption tower 3 is filled with absorption liquid 4; the cooling device 2 is used to cool the flue gas in the flue gas inlet pipe 1, and the flue gas inlet pipe 1 is provided with a condensed water discharge pipe 32.

[0022] As a further improved technical solution of the present embodiment, the present embodiment also includes an ammonium bicarbonate preparation device, which includes a rich liquid pump 33 whose inlet is connected to the lower part of the absorption tower 3 through a pipeline, a cooling crystallization tank 14 connected to the outlet of the rich liquid pump 33 through a pipeline, a heat exchanger 13 for heat exchange of the cooling crystallization tank 14, a refrigerator 12 for providing a cold source to the heat exchanger 13, an ammonium bicarbonate slurry pump 15 whose inlet is connected to the lower part of the cooling crystallization tank 14 through a pipeline, a hydrocyclone 20 whose inlet is connected to the outlet of the ammonium bicarbonate slurry pump 15 through a pipeline, a centrifuge 19 connected to the lower discharge port of the hydrocyclone 20 through a pipeline, a dryer 16 for drying the material at the discharge port of the centrifuge 19, an ammonium bicarbonate silo 17 for storing the material discharged by the dryer 16, and a packaging machine 18 for packaging the material in the ammonium bicarbonate silo 17.

[0023] As a further improved technical solution of the present embodiment, the present embodiment also includes a carbon dioxide preparation device, which includes a rich liquid circulation tank 21 connected to the outlet end of the rich liquid pump 33 through a pipeline at the top, a heat exchanger 29 connected to the rich liquid circulation tank 21 through a circulation pump 36, a gas-liquid separator 28 connected to the top carbon dioxide mixed gas outlet of the heat exchanger 29, a carbon dioxide purification device 25 whose inlet is connected to the exhaust port of the gas-liquid separator 28 through a pipeline, a carbon dioxide compressor 26 whose inlet is connected to the carbon dioxide gas outlet of the carbon dioxide purification device 25 through a pipeline, and a carbon dioxide storage tank 27 for storing carbon dioxide liquid discharged by the carbon dioxide compressor 26; the ammonia gas outlet of the carbon dioxide purification device 25 is connected to the lower part of the absorption liquid tank 10 through an ammonia pipeline 24;

[0024] The liquid discharge port of the centrifuge 19 and the upper liquid discharge port of the hydrocyclone 20 are connected to the absorption liquid tank 10 through pipelines respectively.

[0025] As a technical solution for further improvement of this embodiment, a drain pipe 23 is arranged on the rich liquid circulation tank 21, and the drain pipe 23 is connected to the absorption liquid tank 10. When the carbon dioxide concentration in the rich liquid circulation tank 21 drops to the range limited by the valve, the liquid in the circulation tank returns to the absorption liquid tank 10 through the drain pipe 23, so as to facilitate the recycling of the liquid in the absorption liquid tank 10.

[0026] As a further improved technical solution of this embodiment, the spray layer group includes a first spray layer 5 and a second spray layer 6 located above the first spray layer 5, the inlet of the first spray layer 5 is connected to a first spray pump 8 through a pipeline, and the inlet of the first spray pump 8 is connected to the lower part of the absorption tower 3 through a pipeline; the inlet of the second spray layer 6 group is connected to the second spray pump 9 through a pipeline, and the inlet of the second spray pump 9 is connected to the lower part of the absorption liquid tank 10 through a pipeline.

[0027] The system works as follows:

[0028] The flue gas to be treated first enters the cooling device 2 to reduce the temperature to 20-25°C, and a large amount of condensed water is precipitated, which can be used as water for the desulfurization tower. The cooled flue gas enters the absorption tower 3, and the inorganic ammonia and catalyst solution in the absorption tower 3 effectively absorb the carbon dioxide in the flue gas to generate ammonium bicarbonate. The saturated ammonium bicarbonate crystal slurry after absorption is transported by the corresponding equipment to the cooling stirring crystallization tank 14 and the heat exchange device 29 for different treatments; the saturated ammonium bicarbonate crystal slurry discharged from the cooling crystallization tank 14 enters the hydrocyclone 20 to achieve solid-liquid separation, and the cyclone liquid returns to the absorption liquid tank 10. The water-containing ammonium bicarbonate solid crystals are dehydrated by the centrifuge 19 and dried, and then enter the ammonium bicarbonate silo 17 and are packaged and sold as ammonium bicarbonate fertilizer. When a part of the saturated ammonium bicarbonate crystal slurry is used to produce ammonium bicarbonate fertilizer, the other part first enters the rich liquid circulation tank 21 and enters the heat exchange device 29 through the circulation pump 36. The high-temperature flue gas 35 before desulfurization can be used to heat the heat exchange device 29 (the flue gas 34 after heat exchange is returned to the desulfurization system for further desulfurization), so that the saturated ammonium bicarbonate crystal slurry in the heat exchange device 29 is heated, decomposed and analyzed into a mixed gas of carbon dioxide, ammonia and water vapor, and discharged from the top of the heat exchange device 29 into the gas-liquid separator 28, and the liquid enters the circulation tank 21. The gas-liquid separator 28 is used to separate the water vapor in carbon dioxide and ammonia. Carbon dioxide and ammonia then enter the carbon dioxide purification device 25 for separation. The carbon dioxide gas is compressed and pressurized and liquefied into the carbon dioxide storage tank 27 for storage, and the ammonia enters the absorption liquid tank 10 through the ammonia pipeline 24. After the flue gas absorbs carbon dioxide through the first spray layer 5, it continues to rise to the second spray layer 6 to absorb carbon dioxide, and then passes through the combined demister 7 for defogger and then is discharged to prevent ammonia from escaping.

[0029] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. An ammonia flue gas decarbonization and comprehensive utilization device, comprising an absorption tower (3) having a flue gas inlet pipe (1) and a flue gas outlet (30), an absorption liquid tank (10), a spray layer group for spraying absorption liquid into the absorption tower (3), a combined demister (7) for demisting the absorption tower (3), and a cooling device (2); the lower part of the absorption tower (3) is filled with absorption liquid (4); characterized in that: The cooling device (2) is used to cool the flue gas in the flue gas inlet pipe (1), and the flue gas inlet pipe (1) is provided with a condensed water discharge pipe (32).

2. The device for ammonia flue gas decarbonization and comprehensive utilization according to claim 1 is characterized in that: The invention also comprises an ammonium bicarbonate preparation device, which comprises a rich liquid pump (33) whose inlet is connected to the lower part of the absorption tower (3) through a pipeline, a cooling crystallization tank (14) whose outlet is connected to the rich liquid pump (33) through a pipeline, a heat exchanger (13) used for heat exchange of the cooling crystallization tank (14), a refrigerator (12) used for providing a cold source to the heat exchanger (13), an ammonium bicarbonate slurry pump (15) whose inlet is connected to the lower part of the cooling crystallization tank (14) through a pipeline, a hydrocyclone (20) whose inlet is connected to the outlet of the ammonium bicarbonate slurry pump (15) through a pipeline, a centrifuge (19) connected to the lower discharge port of the hydrocyclone (20) through a pipeline, a dryer (16) used for drying materials at the discharge port of the centrifuge (19), an ammonium bicarbonate silo (17) used for storing materials discharged from the dryer (16), and a packaging machine (18) used for packaging materials in the ammonium bicarbonate silo (17).

3. The device for ammonia flue gas decarbonization and comprehensive utilization according to claim 2 is characterized in that: It also includes a carbon dioxide preparation device, which includes a rich liquid circulation tank (21) whose upper part is connected to the outlet end of a rich liquid pump (33) through a pipeline, a heat exchange device (29) connected to the rich liquid circulation tank (21) through a circulation pump (36), a gas-liquid separator (28) connected to the carbon dioxide mixed gas outlet at the top of the heat exchange device (29), a carbon dioxide purification device (25) whose inlet is connected to the exhaust port of the gas-liquid separator (28) through a pipeline, a carbon dioxide compressor (26) whose inlet is connected to the carbon dioxide gas outlet of the carbon dioxide purification device (25) through a pipeline, and a carbon dioxide storage tank (27) for storing carbon dioxide liquid discharged by the carbon dioxide compressor (26); the ammonia gas outlet of the carbon dioxide purification device (25) is connected to the lower part of the absorption liquid tank (10) through an ammonia pipeline (24); The liquid discharge port of the centrifuge (19) and the upper liquid discharge port of the hydrocyclone (20) are respectively connected to the absorption liquid tank (10) through pipelines.

4. The device for ammonia flue gas decarbonization and comprehensive utilization according to claim 3 is characterized in that: A liquid discharge pipe (23) is provided on the rich liquid circulation tank (21), and the liquid discharge pipe (23) is connected to the absorption liquid tank (10).

5. The device for ammonia flue gas decarbonization and comprehensive utilization according to any one of claims 2 to 4, characterized in that: The spray layer group comprises a first spray layer (5) and a second spray layer (6) located above the first spray layer (5); the inlet of the first spray layer (5) is connected to a first spray pump (8) through a pipeline, and the inlet of the first spray pump (8) is connected to the lower part of the absorption tower (3) through a pipeline; the inlet of the second spray layer (6) group is connected to a second spray pump (9) through a pipeline, and the inlet of the second spray pump (9) is connected to the lower part of the absorption liquid tank (10) through a pipeline.

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