Unsaturated deamination device for cement kiln flue gas

Abstract

The utility model discloses an unsaturated deamination device for cement kiln flue gas, which comprises a tail gas adjusting tower and a tail gas deamination tower, folded plate demisters are additionally arranged at the top of the tail gas adjusting tower and the top of the tail gas deamination tower, and a wire mesh demister is arranged above the folded plate demisters; a flue gas pre-scrubber and a flue gas three-layer spraying system are also arranged in the tail gas adjusting tower; the tail gas deamination tower is also internally provided with a deamination circulating spraying system and is matched with a set of acid supply system; the adjusting tower is arranged to further remove dust and impurities in the tail gas, so that the quality of an ammonium sulfate product is ensured; the tail gas adjusting tower and the deamination tower both adopt empty tower spraying and low pressure drop, to-be-treated flue gas adopts a process route of washing purification, sulfuric acid deamination and byproduct recovery, the problem of flue gas pollution in the existing cement production process is solved, the process is short, the investment is small, the energy consumption is low, and the operation is stable.

Description

Technical Field

[0001] The utility model belongs to the field of chemical environmental protection, and specifically relates to an unsaturated ammonia removal device for cement kiln flue gas. Background Art

[0002] The flue gas of the rotary kiln of the cement production line is treated with 20% ammonia water for denitrification. The ammonia escape produced by denitrification will increase the ammonia emission concentration. Coupled with the presence of background ammonia in the raw material, the ammonia concentration in the flue gas exceeds the standard, forming secondary pollution, high pressure for environmental protection acceptance, affecting air quality and deteriorating the environment. In order to make the ammonia concentration in the flue gas meet the requirements of the national and local environmental protection departments, it is urgent to treat the ammonia escaped in the flue gas to meet the emission standards and meet the environmental protection requirements. Utility Model Content

[0003] The utility model aims to provide a device for unsaturated deamination of cement kiln flue gas. The flue gas to be treated adopts the process route of "washing purification + sulfuric acid deamination + by-product recovery" to solve the flue gas pollution problem in the existing cement production process.

[0004] The technical scheme of the utility model is a device for unsaturated deamination of flue gas in cement kiln, comprising a tail gas regulating tower and a tail gas deamination tower, characterized in that folded plate demisters are arranged on the top of the tail gas regulating tower and the top of the tail gas deamination tower, and a wire mesh demister is arranged above the folded plate demister; a flue gas pre-scrubber and a three-layer flue gas spray system are also arranged in the tail gas regulating tower; a deamination circulating spray system and an acid supply system are also arranged in the tail gas deamination tower, and the acid supply system includes a sulfuric acid storage tank and a sulfuric acid delivery pump;

[0005] Three washing circulation pumps are provided at the bottom of the tail gas regulating tower, and the three washing circulation pumps 5 are respectively connected to the three-layer flue gas spraying system through pipelines; the top of the tail gas regulating tower is connected to the lower part of the tail gas deamination tower through a pipeline; a sulfuric acid delivery pump is provided at the bottom of the sulfuric acid storage tank, and the sulfuric acid delivery pump is connected to the lower part of the tail gas deamination tower through a pipeline; four absorption circulation pumps are provided at the bottom of the tail gas regulating tower, which are respectively connected to the four-layer deamination circulation spraying system; an ammonium sulfate slurry pump is also provided at the bottom of the tail gas regulating tower, which is connected to the ammonium sulfate evaporation and drying system through a pipeline;

[0006] The high-temperature flue gas from the tail exhaust fan first enters the flue gas pre-scrubber at the bottom of the tail gas conditioning tower for the first scrubbing. The cooled flue gas quickly enters the three-layer flue gas spray system for the second scrubbing. The incompletely absorbed flue gas continues to rise, passes through the folded plate demister and the wire mesh demister for two-stage demisting, and then enters the tail gas deamination tower from the top of the tail gas conditioning tower;

[0007] The washing liquid flows to the bottom of the tower by gravity, flows into the washing circulation pump, and is supplied to the deammoniation circulation spraying system through the washing circulation pump. The high-temperature flue gas from the tail exhaust fan is circulated and sprayed to wash it, thereby reducing the temperature of the flue gas and removing ammonia from the flue gas.

[0008] 98% sulfuric acid is used as absorbent to enter the sulfuric acid storage tank. The sulfuric acid delivery pump automatically replenishes the absorption liquid according to the pH signal of the absorption liquid, so that the pH value of the absorption liquid is maintained at about 4.5-5.5. The absorption circulation pump supplies it to the deamination circulation spray system to remove ammonia in the flue gas entering the tail gas deamination tower. Then, it passes through the two-stage demisting of the folded plate demister and the wire mesh demister before meeting the emission standards.

[0009] Ammonia in the flue gas entering the tail gas deammonification tower undergoes a reduction reaction with 98% sulfuric acid from the self-absorption circulation pump to produce ammonium sulfate solution, and the waste heat of the flue gas is used to concentrate the ammonium sulfate solution to produce an unsaturated ammonium sulfate solution; the unsaturated ammonium sulfate solution is pressurized by an ammonium sulfate slurry pump and enters the ammonium sulfate evaporation and drying system to separate ammonium sulfate crystals from the mother liquor and produce ammonium sulfate products.

[0010] Furthermore, the deammonification circulating spray system is arranged as four-level spray layers from top to bottom to circulate and absorb ammonia in the flue gas; the nozzles between two adjacent layers of the four-level spray layers are staggered, and a sufficient number of nozzles must be arranged on each layer. The water mist sprayed from adjacent nozzles overlaps and covers each other without leaving any gaps, so that the sprayed droplets completely cover the entire cross-section of the spray tower, and the spray area coverage rate is guaranteed to be more than 200%.

[0011] Furthermore, an agitator is arranged at the bottom of the tail gas deammoniation tower to prevent the ammonium sulfate slurry from precipitating and settling at the bottom. The absorption liquid in the tower bottom is pressurized by the ammonium sulfate slurry pump and then enters the ammonium sulfate evaporation and drying system to produce an ammonium sulfate product with a moisture content of less than 5%.

[0012] Furthermore, the folded plate demister is provided with a two-way circulating water spraying device, which automatically sprays process water for washing, and further absorbs dust and particulate matter present in the flue gas.

[0013] Furthermore, a bottom-up reverse washing device is provided below the wire mesh demister to automatically spray process water for washing, thereby further absorbing dust and particulate matter present in the flue gas.

[0014] Furthermore, the water supply system provides supplementary process water for the flue gas pre-scrubber, the two-way circulation water spraying device, and the reverse scrubbing device.

[0015] Furthermore, a pH display control system is provided between the sulfuric acid delivery pump and the ammonium sulfate slurry discharge pump.

[0016] The utility model has the following beneficial effects

[0017] 1. Set up a regulating tower to further remove dust and impurities in the tail gas to ensure the quality of ammonium sulfate products;

[0018] 2. Both the tail gas regulating tower and the deamination tower adopt empty tower spraying, with low pressure drop, and the system pressure drop is less than 1500Pa. The residual pressure of the original tail exhaust fan is used, and there is no need to add a new fan;

[0019] 3. Set up an automatic liquid replenishment system according to the pH of the absorption liquid in the deamination tower, which has a high degree of automation and can achieve accurate detection and liquid replenishment;

[0020] 4. Short process, small investment, low energy consumption and stable operation;

[0021] 5. The forced circulation evaporation crystallization system is advanced and reliable, highly efficient and energy-saving, easy to operate and maintain, and has strong adaptability to slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the utility model;

[0023] Among them: 1. Tail gas regulating tower; 2. Tail gas deammonification tower; 3. Flue gas pre-scrubber; 4. Flue gas three-layer spray system; 5. Washing circulation pump; 6. Folding plate demister; 7. Wire mesh demister; 8. Deammonification circulation spray system; 9. Sulfuric acid storage tank; 10. Sulfuric acid delivery pump; 11. Agitator; 12. Absorption circulation pump; 13. Ammonium sulfate slurry pump; 14. Ammonium sulfate evaporation and drying system; 15. Water supply system; 16. Two-way circulation water spray device; 17. Reverse washing device; 18. pH display control system. DETAILED DESCRIPTION

[0024] like Figure 1 As shown, the high-temperature flue gas from the tail exhaust fan enters the tail gas regulating tower 1 tangentially from the air inlet below the tower body, and the process water from the water supply system 15 is introduced into the flue gas pre-scrubber 3 to pre-wash the high-temperature flue gas and quickly fill the air inlet section space, and then evenly rises to the flue gas three-layer spray system 4 for absorption and washing. The washing liquid flows to the tower kettle by gravity and circulates and sprays the high-temperature flue gas from the tail exhaust fan through the washing circulation pump 5 to further reduce the dust content in the tail gas, reduce the demister load, complete the flue gas cooling, and reduce the tail gas temperature to 60-65°C, with a pressure drop of 1.8-3.0Kpa.

[0025] Furthermore, a folded plate demister 6 is added to the top of the exhaust gas regulating tower 1, and the smoke that is not completely absorbed continues to rise. A two-way circulating water spraying device 16 is used to automatically spray process water for washing. The smoke passes through the curved channel of the folded plate demister 6, and the smoke is quickly and continuously changed in direction. Due to the effects of centrifugal force and inertia, the droplets in the smoke hit the blades of the folded plate demister 6 and are captured. The droplets gather to form a water flow, which falls to the bottom of the tower due to gravity and flows into the washing circulation pump 5 to achieve gas-liquid separation.

[0026] Furthermore, a wire mesh demister 7 is added above the folded plate demister 6, and a bottom-up reverse washing device 17 is provided below the wire mesh demister 7 to further absorb dust and particulate matter in the flue gas, and adsorb the fine liquid droplets entrained in the flue gas on the wire mesh through its own attraction and the capillary action of the wire mesh, and gradually form large droplets through the aggregation of the droplets, which drip to the bottom of the tower under the action of gravity. The folded plate demister 6 is provided with a differential pressure gauge, and the reverse washing device 17 is automatically opened when the pressure difference is large.

[0027] The two-stage demisting system removes the acid mist and dust particles carried in the flue gas, preventing the mist from being carried in and causing the concentration of the absorption liquid in the deamination tower to become thinner. The flue gas carrying a large amount of ammonia enters the lower part of the tail gas deamination tower 2 from the top of the tail gas regulating tower 1.

[0028] Furthermore, the tail gas deamination tower 2 adds a deamination circulating spray system 8, which is arranged as a four-stage spray from top to bottom to circulate and absorb ammonia in the flue gas. The nozzles between two adjacent layers of the four-stage spray are staggered, and a sufficient number of nozzles must be arranged on each layer. The water mist sprayed from adjacent nozzles overlaps with each other without leaving any gaps, so that the sprayed droplets completely cover the entire cross-section of the deamination tower, and the spray area coverage rate is guaranteed to be more than 200%. The reasonable structural setting can effectively guarantee the contact, residence, absorption and washing time of gas, liquid and solid, and ensure the ammonia washing efficiency in the flue gas.

[0029] An acid supply system is set up, and 98% concentration sulfuric acid is used as an absorbent to enter the sulfuric acid storage tank 9. The sulfuric acid storage tank 9 is equipped with a liquid level display controller. According to the signal of the pH display control system 18, the sulfuric acid delivery pump 10 automatically replenishes the tail gas deamination tower 2, so that the pH value of the absorption liquid at the bottom of the tail gas deamination tower 2 is maintained at about 4.5-5.5, and is supplied to the deamination circulation spray system 8 through the absorption circulation pump 12 to remove ammonia in the flue gas.

[0030] The pH display control system 18 can automatically adjust the pH value (acidity and alkalinity) of the deammoniation tower absorption liquid. By setting the control range of the pH value to be controlled, the controller will automatically control the emission of acid or alkali, so that the pH value of the measured liquid can be stabilized within a certain range, and the control is completed fully automatically.

[0031] Furthermore, an agitator 11 is provided at the bottom of the tail gas deammoniation tower 2 to prevent the ammonium sulfate slurry from precipitating and settling at the bottom. The absorption liquid in the tower bottom is pressurized by the ammonium sulfate slurry pump 13 and enters the ammonium sulfate evaporation and drying system 14 to produce an ammonium sulfate product with a moisture content of less than 5%.

[0032] Furthermore, a folded plate demister 6 is added to the top of the tail gas deammonification tower 2, and an upper and lower two-layer bidirectional circulating water spray device 16 is used for automatic spray washing. The flue gas passes through the curved channel of the folded plate demister 6, and the flue gas is quickly and continuously changed in direction of movement. Due to the effects of centrifugal force and inertia, the droplets in the flue gas hit the blades of the folded plate demister 6 and are captured. The droplets gather to form a water flow, which falls to the bottom of the tower due to gravity and flows into the absorption circulation pump 12 to achieve gas-liquid separation, so that the flue gas flowing through the folded plate demister 6 meets the demisting requirements and is discharged upward.

[0033] Furthermore, a wire mesh demister 7 is added above the folded plate demister 6, and a bottom-up reverse washing device 17 is arranged below the wire mesh demister 7 to further absorb ammonia present in the flue gas, and adsorb the fine liquid droplets entrained in the flue gas on the wire mesh through its own attraction and the capillary action of the wire mesh, and gradually form large droplets through the aggregation of droplets, which drip into the tower bottom under the action of gravity.

[0034] The two-stage demisting system removes the acid mist and dust particles in the flue gas to ensure the absorption efficiency of ammonia and reduce the ammonia content of the flue gas from 250mg / m 3 Reduce to 8 mg / m 3 Below, the deamination effect is achieved, and the clean gas is discharged from the top of the tower.

Claims

1. A cement kiln flue gas unsaturated deamination device, comprising a tail gas regulating tower (1) and a tail gas deamination tower (2), characterized in that A folded plate demister (6) is provided at the top of the tail gas regulating tower (1) and the top of the tail gas deamination tower (2), and a wire mesh demister (7) is provided above the folded plate demister (6); a flue gas pre-scrubber (3) and a flue gas three-layer spray system (4) are also provided in the tail gas regulating tower (1); a deamination circulation spray system (8) and an acid supply system are also provided in the tail gas deamination tower (2), and the acid supply system includes a sulfuric acid storage tank (9) and a sulfuric acid delivery pump (10); Three washing circulation pumps (5) are provided at the bottom of the tail gas regulating tower (1), and the three washing circulation pumps (5) are respectively connected to the three-layer flue gas spray system (4) through pipelines; the top of the tail gas regulating tower (1) is connected to the lower part of the tail gas deamination tower (2) through pipelines; a sulfuric acid delivery pump (10) is provided at the bottom of the sulfuric acid storage tank (9), and the sulfuric acid delivery pump (10) is connected to the lower part of the tail gas deamination tower (2) through pipelines; four absorption circulation pumps are provided at the bottom of the tail gas regulating tower (1) and are respectively connected to the four-layer deamination circulation spray system (8); and an ammonium sulfate slurry pump (13) is also provided at the bottom of the tail gas regulating tower (1) and is connected to the ammonium sulfate evaporation and drying system (14) through pipelines.

2. The unsaturated deamination device for cement kiln flue gas as claimed in claim 1, characterized in that: The deammonification circulating spray system (8) is arranged as four spray layers from top to bottom to circulate and absorb ammonia in the flue gas; the nozzles between two adjacent layers of the four spray layers are arranged in a staggered manner.

3. The unsaturated deamination device for cement kiln flue gas as claimed in claim 2, characterized in that: A stirrer (11) is arranged at the bottom of the tail gas deammoniation tower (2) to prevent the ammonium sulfate slurry from precipitating and settling at the bottom. The absorption liquid in the tower bottom is pressurized by an ammonium sulfate slurry pump (13) and then enters a subsequent ammonium sulfate evaporation and drying system (14) to produce an ammonium sulfate product with a moisture content of less than 5%.

4. The unsaturated deamination device for cement kiln flue gas according to claim 1, characterized in that: The folded plate demister (6) is provided with a two-way circulating water spraying device (16) for automatically spraying process water for washing, thereby further absorbing dust and particulate matter present in the flue gas.

5. The unsaturated deamination device for cement kiln flue gas according to claim 1, characterized in that: A bottom-up reverse washing device (17) is provided below the wire mesh demister (7) to automatically spray process water for washing, thereby further absorbing dust and particulate matter present in the flue gas.

6. A cement kiln flue gas unsaturated ammonia removal device as claimed in claim 1, 4 or 5, characterized in that: The water supply system (15) provides supplementary process water for the flue gas pre-scrubber (3), the two-way circulation water spraying device (16), and the reverse scrubbing device (17).

7. The unsaturated deamination device for cement kiln flue gas as claimed in claim 6, characterized in that: A pH display control system (18) is provided between the sulfuric acid delivery pump (10) and the ammonium sulfate slurry discharge pump (13).

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