A flue gas dechlorination system based on an optimized flow field reaction

Abstract

The present invention discloses a flue gas dechlorination system based on an optimized flow field reaction. The outlet of the cleaning water tank is connected to the inlet of the spray pump. The outlet of the chemical dosing tank is connected to the inlet of the chemical dosing pump. The outlet of the chemical dosing pump is connected to the inlet of the spray water tank. The outlet of the spray water tank is connected to the inlet of the spray pump. The outlet of the spray pump is connected to the inlet of the spray gun. The outlet of the air compressor is connected to the inlet of the spray gun. Each atomizing nozzle on the spray gun is located in the outlet flue of the air preheater, and each atomizing nozzle is evenly distributed on the same cross-section of the outlet flue. The outlet flue is connected to the optimized flow field reaction zone. A reaction chamber is arranged in the flow field optimization reaction zone. A flue gas circulator is arranged in the reaction chamber. A regulator is arranged at the outlet of the optimized flow field reaction zone. A booster fan is arranged at the outlet of the regulator. A secondary hot air duct is connected in parallel to the flow field optimization reaction zone. An air volume regulating valve is arranged on the secondary hot air duct. This system can increase the contact degree between the flue gas and the base solution and improve the efficiency of the dechlorination reaction.

Description

Technical Field

[0001] The invention belongs to the field of flue gas dechlorination and desulfurization wastewater treatment, and relates to a flue gas dechlorination system based on optimized flow field reaction. Background Art

[0002] One of the important factors for the discharge of desulfurization wastewater is the excessive chloride ion concentration in it, which causes corrosion of the desulfurization tower and auxiliary equipment. Currently, some scholars have proposed to remove HCl from the flue gas in advance to reduce the chlorine element entering the desulfurization tower, thereby reducing the chloride ions in the desulfurization wastewater and increasing the circulation times of the desulfurization slurry to achieve the purpose of reducing the desulfurization wastewater. This flue gas dechlorination technology is also called semi-dry dechlorination, which is widely used in waste incineration power plants. Its principle is to configure a base solution and spray it into the dechlorination tower in the form of a spray. The HCl in the flue gas is absorbed by the base solution, and the generated salt is evaporated dry by the waste heat of the flue gas and enters the dust collector together with the fly ash and is captured. At present, this technology has not been applied to coal-fired power plants. One of the reasons is that the HCl concentration in coal-fired flue gas is relatively low, only a dozen to dozens of ppm, and the flue gas contains a high concentration of SO 2 , which will form competition with HCl during the reaction with the base solution. Therefore, a relatively high Na / Cl ratio is required, which undoubtedly increases the cost of dechlorination. On the other hand, the flue gas flow rate of coal-fired power plants is very large, and the cost of setting up a separate dechlorination tower is huge. Therefore, it is necessary to remove HCl by directly spraying the base solution in the flue duct. Currently, there are already some patents on semi-dry dechlorination of coal-fired power plants using the waste heat of flue gas. Its main process flow is to configure the base solution with the upgraded desulfurization wastewater, absorb HCl in the form of a spray in the flue duct after the dust collector, and then be evaporated dry by the waste heat of the flue gas. The salt after the reaction enters the dust collector together with the fly ash and is captured. However, as mentioned above, the flue gas flow rate of coal-fired power plants is large, the HCl concentration is very low, and there is a risk of competition with SO 2 . Therefore, how to ensure the full contact and mixing of the base solution and the flue gas, and then improve the dechlorination efficiency is the biggest difficulty of the semi-dry dechlorination technology at present. Summary of the Invention

[0003] The purpose of the invention is to overcome the above-mentioned disadvantages of the prior art and provide a flue gas dechlorination system based on optimized flow field reaction, which can increase the contact degree between the flue gas and the base solution and improve the efficiency of the dechlorination reaction.

[0004] To achieve the above purpose, the flue gas dechlorination system based on optimized flow field reaction described in the invention includes a cleaning water tank, a chemical dosing tank, a chemical dosing pump, a spray water tank, a spray pump, an air compressor, a spray gun, an atomizing nozzle, an air preheater, an optimized flow field reaction zone, a booster fan and an air volume regulating valve;

[0005] The outlet of the cleaning water tank is connected to the inlet of the spray pump, the outlet of the chemical dosing tank is connected to the inlet of the chemical dosing pump, the outlet of the chemical dosing pump is connected to the inlet of the spray water tank, the outlet of the spray water tank is connected to the inlet of the spray pump, the outlet of the spray pump is connected to the inlet of the spray gun, the outlet of the air compressor is connected to the inlet of the spray gun, each atomizing nozzle on the spray gun is located in the outlet flue of the air preheater, and the atomizing nozzles are evenly distributed on the same cross-section of the outlet flue. The outlet flue is connected to the optimized flow field reaction zone, a reaction chamber is arranged in the flow field optimization reaction zone, a flue gas circulator is arranged in the reaction chamber, a regulator is arranged at the outlet of the optimized flow field reaction zone, a booster fan is arranged at the outlet of the regulator, a secondary hot air pipe is connected in parallel to the flow field optimization reaction zone, and an air volume regulating valve is arranged on the secondary hot air pipe.

[0006] The base solution in the chemical dosing tank is a strong base solution including sodium base and calcium base or a weak acid strong base salt solution.

[0007] The materials of the spray water tank, chemical dosing tank, chemical dosing pump, spray water tank and spray pump are corrosion-resistant PP, PE, UPVC or stainless steel.

[0008] The atomizing nozzle is a pressure atomizing nozzle or a two-phase flow atomizing nozzle.

[0009] The outlet flue of the air preheater is a horizontal flue or a vertical flue.

[0010] A regulating valve for controlling the flow rate and spray pressure is arranged on the spray gun.

[0011] When the unit is operating at full load, the opening of the regulating valve is adjusted to the maximum. When the unit load is less than its full load, the injection volume under the current unit load is calculated, and then the opening of the regulating valve is adjusted according to the injection volume.

[0012] The outlet of the spray pump is connected to the inlet of the spray gun through a spray water pipe.

[0013] The outlet of the air compressor is connected to the inlet of the spray gun through a compressed air pipe.

[0014] The present invention has the following beneficial effects:

[0015] When the flue gas dechlorination system based on the optimized flow field reaction described in the present invention is in specific operation, each atomizing nozzle on the spray gun is located in the flue duct, and each atomizing nozzle is on the same cross-section of the outlet flue duct of the air preheater, and the atomizing nozzles are evenly distributed. During actual operation, by adjusting the number of atomizing nozzles, the coverage rate of the base liquid spray in the outlet flue duct under complex working conditions is ensured. Further, by adding an optimized flow field reaction zone, the atomized droplets are brought into the inlet of the flue gas circulator by the hot flue gas for sufficient mixing reaction. The hot flue gas in the secondary hot air duct tangentially enters the reaction chamber, causing the heavier circulating particles to generate a spiral motion, increasing the reaction residence time to achieve the maximum removal of HCl, while ensuring the full drying of the base liquid and avoiding flue duct scaling. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of the present invention;

[0017] Wherein, 1 is a cleaning water tank, 2 is a chemical dosing tank, 3 is a chemical dosing pump, 4 is a spray water tank, 5 is a spray pump, 6 is an air compressor, 7 is a spray gun, 8 is an atomizing nozzle, 9 is an air preheater, 10 is a reaction chamber, 11 is a secondary hot air duct, 12 is a flue gas circulator, 13 is a regulator, 14 is a booster fan, and 15 is an air volume regulating valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] In order to enable those skilled in the art of the present technology to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present invention disclosure. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessarily confusing the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0019] The schematic structural diagrams according to the disclosed embodiments of the present invention are shown in the drawings. These figures are not drawn to scale, and for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary, and may actually deviate due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0020] Refer to Figure 1, the flue gas dechlorination system based on optimized flow field reaction described in the present invention includes a cleaning water tank 1, a chemical dosing tank 2, a chemical dosing pump 3, a spray water tank 4, a spray pump 5, an air compressor 6, a spray gun 7, atomizing nozzles 8, an air preheater 9, a reaction chamber 10, a secondary hot air duct 11, a flue gas circulator 12, a regulator 13, a booster fan 14 and an air volume regulating valve 15;

[0021] The outlet of the cleaning water tank 1 is connected to the inlet of the spray pump 5, the outlet of the chemical dosing tank 2 is connected to the inlet of the chemical dosing pump 3, the outlet of the chemical dosing pump 3 is connected to the inlet of the spray water tank 4, the outlet of the spray water tank 4 is connected to the inlet of the spray pump 5, the outlet of the spray pump 5 is connected to the inlet of the spray gun 7 through a spray water pipe, the outlet of the air compressor 6 is connected to the inlet of the spray gun 7 through a compressed air pipe, each atomizing nozzle 8 on the spray gun 7 is located in the outlet flue of the air preheater 9, and each atomizing nozzle 8 is evenly distributed on the same cross-section of the outlet flue. The outlet flue is connected to the optimized flow field reaction zone, a reaction chamber 10 is arranged in the flow field optimized reaction zone, a flue gas circulator 12 is arranged in the reaction chamber 10, a regulator 13 is arranged at the outlet of the optimized flow field reaction zone, a booster fan 14 is arranged at the outlet of the regulator 13, the flow field optimized reaction zone is connected in parallel with a secondary hot air duct 11, and an air volume regulating valve 15 is arranged on the secondary hot air duct 11.

[0022] The cleaning water tank 1 is used for the spray gun 7 and the atomizing nozzles 8.

[0023] The chemical dosing tank 2 is used for preparing and temporarily storing base solutions with different concentrations. The base solutions include strong base solutions or weak acid strong base salt solutions of sodium-based and calcium-based, and the mass concentration is 10%-40%.

[0024] The spray water tank 4 is used for continuously conveying the base liquid to the spray gun 7 and shares a spray pump 5 with the cleaning water tank 1.

[0025] The materials of the spray water tank 4, the chemical dosing tank 2, the chemical dosing pump 3, the spray water tank 4 and the spray pump 5 are corrosion-resistant materials such as PP, PE, UPVC or stainless steel.

[0026] The atomizing nozzle 8 is a pressure atomizing nozzle or a two-phase flow atomizing nozzle.

[0027] The outlet flue of the air preheater 9 is a horizontal flue or a vertical flue.

[0028] A regulating valve for controlling the flow rate and spray pressure is arranged on the spray gun 7. When the unit operates at full load (100%), the opening of the regulating valve is adjusted to the maximum. When the unit load is less than its full load (100%), the injection volume under the current unit load is calculated, and then the opening of the regulating valve is adjusted according to the injection volume.

[0029] By adjusting the power of the spray pump 5 and the air compressor 6, the pressure of the base liquid and the volume of the compressed air are adjusted to achieve the adjustment of the spray particle size.

[0030] One of the atomizing nozzles 8, as the central atomizing nozzle 8, is located at the center of the cross-section of the outlet flue, and the remaining atomizing nozzles 8 are located around the central atomizing nozzle 8 and are evenly distributed at equal intervals in the circumferential direction.

[0031] The atomized droplets output by the atomizing nozzle 8 are carried by the hot flue gas into the inlet of the flue gas circulator 12, and sufficient mixing reaction is carried out. The hot flue gas in the secondary hot air pipe 11 tangentially enters the reaction chamber 10.

[0032] The working process of the present invention is as follows:

[0033] 1) The process water is divided into two paths. Among them, one path enters the cleaning water tank 1, and the other path enters the chemical dosing tank 2 as the chemical dosing water. After the base solution is configured and temporarily stored in the chemical dosing tank 2, it is pumped into the spray water tank 4 through the chemical dosing pump 3. The base solution in the spray water tank 4 is continuously conveyed to the spray gun 7 through the spray pump 5, and the air compressor 6 continuously conveys compressed air to the spray gun 7. After being atomized by the atomizing nozzle 8, a base liquid spray is generated;

[0034] 2) The atomizing nozzle 8 is arranged in the outlet flue of the air preheater 9. The atomized base liquid spray enters the flue gas circulator 12 in the reaction chamber 10 along with the hot flue gas, and is fully mixed, reacted and dried with the hot flue gas. The fly ash meeting the particle size requirements is discharged through the regulator 13. The fly ash particles that are not completely reacted and dried cannot be discharged through the regulator 13, but are tangentially entered into the reaction chamber 10 by the hot flue gas carried by the secondary hot air pipe 11, so that the heavier circulating fly ash particles generate a spiral movement, prolonging the reaction time until they meet the outlet requirements of the regulator 13 and then entering the next processing unit through the booster fan 14. The proportion of the hot flue gas entering the flue gas hot air pipe is adjusted by controlling the opening degree of the air volume regulating valve 15;

[0035] 3) After the base liquid atomizing system works for a period of time, the high temperature inside the flue will cause the base liquid to precipitate inside the spray gun 7. At this time, the spray gun 7 is pulled out, the valve at the outlet of the spray water tank 4 is closed, the valve at the inlet of the cleaning water tank 1 is opened, and the spray gun 7 and the atomizing nozzle 8 are flushed through the spray pump 5. After the cleaning is completed, the valve at the inlet of the cleaning water tank 1 is closed, the valve at the outlet of the spray water tank 4 is opened, and then it turns to step 1).

Claims

1. A flue gas dechlorination system based on an optimized flow field reaction, characterized in that, it includes a cleaning water tank (1), a chemical dosing tank (2), a chemical dosing pump (3), a spray water tank (4), a spray pump (5), an air compressor (6), a spray gun (7), atomizing nozzles (8), an air preheater (9), an optimized flow field reaction zone and a booster fan (14); The outlet of the cleaning water tank (1) is connected to the inlet of the spray pump (5), the outlet of the chemical dosing tank (2) is connected to the inlet of the chemical dosing pump (3), the outlet of the chemical dosing pump (3) is connected to the inlet of the spray water tank (4), the outlet of the spray water tank (4) is connected to the inlet of the spray pump (5), the outlet of the spray pump (5) is connected to the inlet of the spray gun (7), the outlet of the air compressor (6) is connected to the inlet of the spray gun (7), each atomizing nozzle (8) on the spray gun (7) is located in the outlet flue of the air preheater (9), and each atomizing nozzle (8) is evenly distributed on the same cross-section of the outlet flue. The outlet flue is connected to the optimized flow field reaction zone. A reaction chamber (10) is provided in the flow field optimization reaction zone. A flue gas circulator (12) is provided in the reaction chamber (10). A regulator (13) is provided at the outlet of the optimized flow field reaction zone. A secondary hot air duct (11) is connected in parallel to the flow field optimization reaction zone, and an air volume regulating valve (15) is provided on the secondary hot air duct (11); The atomizing nozzles (8) are arranged in the outlet flue of the air preheater (9). The atomized base liquid spray enters the flue gas circulator (12) in the reaction chamber (10) along with the hot flue gas, and is fully mixed, reacted and dried with the hot flue gas. The fly ash meeting the particle size requirements is discharged through the regulator (13). The fly ash particles that are not fully reacted and dried cannot be discharged through the regulator (13), but enter the reaction chamber (10) tangentially with the hot flue gas carried by the secondary hot air duct (11), causing the heavier circulating fly ash particles to generate a spiral motion, extending the reaction time, and then entering the next treatment unit through the booster fan (14) after meeting the requirements at the outlet of the regulator (13). The proportion of hot flue gas entering the flue gas hot air duct is adjusted by controlling the opening of the air volume regulating valve (15).

2. The flue gas dechlorination system based on an optimized flow field reaction according to claim 1, characterized in that, the base solution in the chemical dosing tank (2) is a strong base solution or a weak acid strong base salt solution including sodium-based and calcium-based.

3. The flue gas dechlorination system based on an optimized flow field reaction according to claim 1, characterized in that, the materials of the spray water tank (4), the chemical dosing tank (2), the chemical dosing pump (3), the spray water tank (4) and the spray pump (5) are corrosion-resistant PP, PE, UPVC or stainless steel.

4. The flue gas dechlorination system based on an optimized flow field reaction according to claim 1, characterized in that, the atomizing nozzles (8) are pressure atomizing nozzles or two-phase flow atomizing nozzles.

5. The flue gas dechlorination system based on an optimized flow field reaction according to claim 1, characterized in that, the outlet flue of the air preheater (9) is a horizontal flue or a vertical flue.

6. The flue gas dechlorination system based on an optimized flow field reaction according to claim 1, characterized in that, A regulating valve for controlling the flow rate and spraying pressure is provided on the spray gun (7).

7. The flue gas dechlorination system based on an optimized flow field reaction according to claim 6, characterized in that when the unit is operating at full load, the opening of the regulating valve is adjusted to the maximum; when the unit load is less than its full load, the injection amount at the current unit load is calculated, and then the opening of the regulating valve is adjusted according to the injection amount.

8. The flue gas dechlorination system based on an optimized flow field reaction according to claim 1, characterized in that The outlet of the spray pump (5) is connected to the inlet of the spray gun (7) through a spray water pipe.

9. The flue gas dechlorination system based on an optimized flow field reaction according to claim 1, characterized in that The outlet of the air compressor (6) is connected to the inlet of the spray gun (7) through a compressed air pipeline.

10. The flue gas dechlorination system based on an optimized flow field reaction according to claim 1, characterized in that The hot flue gas in the secondary hot air pipe (11) enters the reaction chamber (10) in a tangential form.

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