A cement kiln flue gas saturation deammoniation device

Abstract

The utility model discloses a saturated deammoniation device for flue gas from a cement kiln, comprising a deammoniation tower and an acid supply system, wherein the acid supply system comprises a sulfuric acid storage tank, a sulfuric acid delivery pump, an absorption circulation pump, and an absorption liquid buffer tank; a two-stage acid washing spray device, a liquid collecting box, an absorption spray device, a folding plate demister, and a wire mesh demister are arranged from bottom to top in the deammoniation tower. The flue gas to be treated adopts the process route of ammonium sulfate concentration and sulfuric acid deammoniation, and the upper and lower sections of the deammoniation tower are graded for absorption, the upper section adopts non-saturated absorption, and the lower section adopts supersaturated concentration, which not only ensures the saturated concentration of the mother liquor in the concentration section, but also ensures the absorption efficiency of ammonia in the acid washing section, so that the ammonia content of the tail gas is increased from 250mg / m 3 Reduce to 8 mg / m 3 The following, comply with emission standards, while producing ammonium sulfate products.

Description

Technical Field

[0001] The utility model belongs to the field of chemical environmental protection, and specifically relates to a device for saturated deammoniation treatment of cement kiln flue gas and product recovery. Background Art

[0002] As we all know, cement will produce a lot of flue gas pollutants during the production process, among which NO X The emission volume is very large. The current mainstream process for cement denitrification is the selective catalytic reduction (SCR) denitrification process, which uses 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 exhaust gas exceeds the standard, forming secondary pollution, high pressure on environmental protection acceptance, affecting air quality and worsening the environment.

[0003] In order to control ammonia emissions, most cement companies have adopted gas uniform mixing technologies such as guide plates, rectifier layers and optimized ammonia injection systems. X It is still impossible to fully react, so the ammonia NH3 slip phenomenon in the SCR method cannot be avoided, and the ammonia emission concentration still exceeds 8mg / m 3 , which fails to meet the requirements of national and local environmental protection departments. Utility Model Content

[0004] The utility model aims to provide a cement kiln flue gas saturation deammoniation device, which adopts saturated absorption to reduce the ammonia content of the tail gas from 250mg / m 3 Reduce to 8 mg / m 3 The following, comply with emission standards, while producing ammonium sulfate products.

[0005] The utility model solves the above-mentioned problem by adopting the following technical scheme: a cement kiln flue gas saturated deamination device, comprising a deamination tower, characterized in that it also comprises an acid supply system, the acid supply system comprises a sulfuric acid storage tank, a sulfuric acid delivery pump, an absorption circulation pump, and an absorption liquid buffer tank; a two-stage acid washing spray device, a liquid collecting tank, an absorption spray device, a folded plate demister, and a wire mesh demister are arranged from bottom to top in the deamination tower;

[0006] A sulfuric acid delivery pump is provided at the bottom of the sulfuric acid storage tank, the sulfuric acid delivery pump is connected to the absorption liquid buffer tank pipeline, the absorption liquid buffer tank is connected to the collecting tank pipeline, the bottom of the absorption liquid buffer tank is connected to the absorption circulation pump through a pipeline, the absorption circulation pump is connected to the absorption spray device through a pipeline, and the absorption circulation pump is connected to the upper part of the flue gas inlet of the deamination tower through a pipeline;

[0007] An ammonium sulfate slurry pump is provided at the bottom of the deammoniation tower, which is connected to the pipeline at the top of the crystallization tank. A centrifuge is provided at the bottom of the crystallization tank, and the centrifuge and the crystallization tank are simultaneously connected to the middle pipeline of the deammoniation tower. Two mother liquor concentration pumps are also provided at the bottom of the deammoniation tower, which are respectively connected to the pipelines of the two-stage acid washing spray device.

[0008] Furthermore, the absorption spray device is provided with four spray layers to cyclically absorb ammonia in the flue gas from the liquid collecting tank, and the nozzles between two adjacent spray layers are arranged in a staggered manner.

[0009] Furthermore, there are four absorption circulation pumps, which respectively provide spraying liquid for four spraying layers.

[0010] Furthermore, an agitator is provided at the bottom of the deamination tower to disturb the mother liquor in the concentration stage and prevent the deposition of suspended solids in the mother liquor.

[0011] Furthermore, the folded plate demister is provided with a two-way flushing device.

[0012] Furthermore, a wire mesh demister is added above the folded plate demister, and a layer of bottom-up reverse flushing device is arranged below the wire mesh demister.

[0013] The utility model has the following beneficial effects

[0014] 1. 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;

[0015] 2. The flue gas to be treated adopts the process route of "ammonium sulfate concentration + sulfuric acid deammoniation". The upper and lower sections of the deammoniation tower are graded for absorption. The upper part adopts non-saturated absorption and the lower part adopts supersaturated concentration, which not only ensures the saturated concentration of the mother liquor in the concentration section, but also ensures the absorption efficiency of ammonia in the pickling section;

[0016] 3. Automatic liquid replenishment is set according to the pH of the absorption liquid in the deamination tower, with a high degree of automation, which can achieve accurate detection and liquid replenishment;

[0017] 4. Short process, small investment, low energy consumption and stable operation;

[0018] 5. It adopts mature crystallization centrifugal technology, which is advanced and reliable, efficient and energy-saving, and easy to operate and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the utility model:

[0020] Among them: 1. Deammoniation tower; 2. Sulfuric acid storage tank; 3. Sulfuric acid delivery pump; 4. Agitator; 5. Ammonium sulfate slurry pump; 6. Mother liquor concentration pump; 7. Pickling spray device; 8. Absorption circulation pump; 9. Absorption liquid buffer tank; 10. Liquid collecting tank; 11. Absorption spray device; 12. Folding plate demister; 13. Two-way backwashing device; 14. Backwashing device; 15. Wire mesh demister; 16. Crystallization tank; 17. Centrifuge. DETAILED DESCRIPTION

[0021] like Figure 1 As shown, a cement kiln flue gas saturated deammoniation device is provided with an acid supply system. Sulfuric acid with a concentration of 98% is used as an absorbent and enters a sulfuric acid storage tank 2. The sulfuric acid is automatically replenished into an absorption liquid buffer tank 9 through a sulfuric acid delivery pump 3 according to the pH signal of the absorption liquid, so that the pH value of the absorption liquid is maintained at about 3 to 4. The absorption liquid is supplied to an absorption spray device 11 through an absorption circulation pump 8 to remove ammonia from the flue gas.

[0022] The high-temperature flue gas from the tail exhaust fan first enters the concentration section at the bottom of the deammoniation tower 1, undergoes a reduction reaction with the 98% sulfuric acid from the self-absorption circulating pump 8 to produce an ammonium sulfate solution, and uses the waste heat of the flue gas to concentrate the ammonium sulfate solution to produce an unsaturated ammonium sulfate solution. The pH of the circulating mother liquor in the concentration section is maintained at around 5 to 6.

[0023] The concentration section is mainly used for cooling the flue gas and concentrating the circulating mother liquor. A two-stage acid washing spray device 7 is arranged from top to bottom to evenly spray the mother liquor and improve the reaction efficiency.

[0024] The mother liquor concentration pump 6 is used to send the unsaturated ammonium sulfate mother liquor to the acid washing spray device 7, and a two-stage acid washing spray head is set from top to bottom to absorb the ammonia in the high-temperature flue gas and reduce the temperature of the flue gas. The cooled flue gas passes through the collecting tank 10 and enters the absorption spray device 11 at the upper part of the concentration section, with a temperature of about 60-70°C. The sprayed unsaturated ammonium sulfate mother liquor absorbs the ammonia in the flue gas.

[0025] A stirrer 4 is provided at the bottom of the deamination tower to disturb the mother liquor in the concentration stage, prevent the deposition of solid suspended matter in the mother liquor, maintain the uniformity of the mother liquor, reduce the adhesion of the mother liquor on the inner wall of the equipment, reduce the gas-liquid resistance, and increase the reaction rate of the mother liquor and the flue gas.

[0026] The saturated ammonium sulfate mother liquor is pressurized by the ammonium sulfate slurry pump 5 and enters the crystallization tank 16 and the centrifuge 17 to separate the ammonium sulfate crystals in the mother liquor and produce the ammonium sulfate product with a water content of less than 2%. The solution separated by centrifugation is refluxed to the acid washing section of the deammonification tower to continue to absorb ammonia in the flue gas.

[0027] The flue gas cooled by the acid washing spray device 7 enters the absorption spray device 11 at the upper part of the concentration section through the collecting tank 10. Four spray layers are arranged to circulate and absorb ammonia in the flue gas from the collecting tank 10. The nozzles between two adjacent layers are arranged in a staggered manner. A sufficient number of nozzles must be arranged on each layer. The water mist sprayed by adjacent nozzles overlaps with each other without leaving any gaps, so that the sprayed droplets completely cover the entire cross-section of the deammonification tower. The spray area coverage rate is guaranteed to be more than 200%. Reasonable structural settings can effectively ensure the contact, residence, absorption and washing time of gas, liquid and solid, and ensure the ammonia washing efficiency in the flue gas.

[0028] A folded plate demister 12 is arranged on the top of the deammoniation tower 1, and a two-way backwashing device 13 is arranged, which automatically circulates and sprays process water for washing. The flue gas passes through the curved channel of the folded plate demister 12, 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 demister blades and are captured. The droplets gather to form a water flow, which falls to the liquid collecting box 10 due to the effect of gravity and flows into the absorption liquid buffer tank 9 to achieve gas-liquid separation, so that the flue gas flowing through the folded plate demister 12 meets the demisting requirements and is discharged.

[0029] The two-way flushing device 13 provided on the folded plate demister 12 ensures that the deammoniation tower demister system can operate continuously and stably for a long time without clogging or scaling, and also supplies process water to the deammoniation tower to adjust the pH value. The flushing water pressure of the demister section facing the airflow direction is higher than the flushing water pressure of the demister section facing away from the airflow direction.

[0030] To ensure the defogger effect, a wire mesh demister 15 is added above the folded plate demister 12, and a bottom-up backwashing device 14 is set below the wire mesh demister to automatically circulate and spray process water to further absorb ammonia in the flue gas. Through its own attraction and the capillary action of the wire mesh, the fine liquid droplets entrained in the flue gas are adsorbed on the wire mesh, and large droplets are gradually formed through the aggregation of droplets, which drip into the liquid collecting tank under the action of gravity.

[0031] 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 The following can achieve the deammonification effect, meet the emission standards and protect the ecological environment.

[0032] The process water is supplemented, part of which is used as flushing water for regulating the deammonification tower and demister, and the rest is added from the pickling section to adjust the pH value.

Claims

1. A cement kiln flue gas saturation deamination device, comprising a deamination tower (1), characterized in that: The deammoniation tower (1) is equipped with an acid supply system, which includes a sulfuric acid storage tank (2), a sulfuric acid delivery pump (3), an absorption circulation pump (8), and an absorption liquid buffer tank (9); a two-stage acid washing spray device (7), a liquid collecting tank (10), an absorption spray device (11), a folded plate demister (12), and a wire mesh demister (15) are arranged from bottom to top in the deammoniation tower (1); A sulfuric acid delivery pump (3) is provided at the bottom of the sulfuric acid storage tank (2), the sulfuric acid delivery pump (3) is connected to the absorption liquid buffer tank (9) through a pipeline, the absorption liquid buffer tank (9) is connected to the liquid collecting tank (10) through a pipeline, the bottom of the absorption liquid buffer tank (9) is connected to the absorption circulation pump (8) through a pipeline, the absorption circulation pump (8) is connected to the absorption spray device (11) through a pipeline, and the absorption circulation pump (8) is connected to the upper part of the flue gas inlet of the deammonification tower (1) through a pipeline; An ammonium sulfate slurry pump (5) is provided at the bottom of the deammoniation tower (1) and is connected to the top pipeline of a crystallization tank (16). A centrifuge (17) is provided at the bottom of the crystallization tank (16); the centrifuge (17) and the crystallization tank (16) are simultaneously connected to the middle pipeline of the deammoniation tower; two mother liquor concentration pumps (6) are also provided at the bottom of the deammoniation tower (1) and are respectively connected to the pipelines of the two-stage acid washing spray device (7).

2. The cement kiln flue gas saturation deammoniation device according to claim 1, characterized in that: The absorption spray device (11) is provided with four spray layers for cyclically absorbing ammonia in the flue gas from the liquid collecting tank (10), and the nozzles between two adjacent spray layers are arranged in a staggered manner.

3. The cement kiln flue gas saturation deammoniation device as claimed in claim 2, characterized in that: There are four absorption circulation pumps (8) which respectively provide spraying liquid for the four spraying layers.

4. The cement kiln flue gas saturation deammoniation device as claimed in claim 1, characterized in that: A stirrer (4) is arranged at the bottom of the deamination tower to disturb the mother liquor in the concentration stage and prevent the deposition of solid suspended matter in the mother liquor.

5. The cement kiln flue gas saturation deammoniation device according to claim 1, characterized in that: The folded plate demister (12) is provided with a two-way flushing device (13).

6. The cement kiln flue gas saturation deammoniation device according to claim 1, characterized in that: A wire mesh demister (15) is added above the folded plate demister (12), and a layer of bottom-up reverse flushing device (14) is arranged below the wire mesh demister.

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