Denitration system based on secondary combustion chamber

Abstract

The utility model discloses a denitration system based on a secondary combustion chamber, which relates to the technical field of flue gas denitration, and adopts the scheme that the denitration system based on the secondary combustion chamber comprises the secondary combustion chamber, the atomizing nozzle is mounted on the inner wall of the secondary combustion chamber; the urea liquid preparation box is installed on the outer wall of the secondary combustion chamber, a urea feeding opening is formed in the top end of the urea liquid preparation box, and a water adding opening is formed in the urea liquid preparation box; one end of the liquid conveying pipe is connected with the atomization nozzle, the other end of the liquid conveying pipe is connected to the interior of the urea liquid preparation box, and a centrifugal pump is installed on the liquid conveying pipe; the motor is mounted at the bottom of the urea liquid preparation box; the urea solution can be quickly and uniformly mixed, and the denitration reaction efficiency is remarkably improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of flue gas denitration, and particularly relates to a denitration system based on a secondary combustion chamber. BACKGROUND

[0002] With the continuous expansion of industrial production scale and the acceleration of urbanization process, the amount of hazardous waste is increasing year by year. Hazardous waste contains a large amount of toxic and harmful substances, such as heavy metals, organic pollutants, radioactive substances, etc. If not properly treated, it will cause serious pollution to the soil, water and atmospheric environment, and harm the ecological balance and human health. Incineration method has become the mainstream technology for hazardous waste disposal due to its characteristics of efficient volume reduction, rapid treatment and deep decomposition of harmful substances. However, hazardous waste incineration will produce pollutants such as nitrogen oxides (NOx), acid gases, dust and dioxins. In order to meet the strict environmental protection requirements, flue gas purification is an essential part of incineration disposal. Among them, the selective non-catalytic reduction (SNCR) denitration technology is widely used. By spraying urea solution into high-temperature flue gas, the ammonia gas generated by its decomposition is used to reduce the reaction with NOx, so as to achieve the removal of nitrogen oxides.

[0003] According to the authorized announcement number (CN213221597U) of a kind of solid waste treatment system for flue gas denitration device, solid waste treatment system includes sequentially connected rotary kiln, two combustion chambers and quench tower, and there is flue gas denitration tower in series communication between the two combustion chambers and the quench tower. Urea dispensing mechanism is composed of dosing tank, water tank and dispensing tank. The dosing tank can send the appropriate amount of urea into the dispensing tank, and the water tank can send the appropriate amount of water into the dispensing tank. The two work together to accurately control the concentration of urea in the dispensing tank, providing stable and efficient reaction conditions for denitration process.

[0004] The structure disclosed in the patent has defects in actual application, specifically as follows. The urea dissolution process in the dispensing tank relies only on natural diffusion mechanism, lacking forced mixing means. Limited by the molecular diffusion rate and the disorder of fluid natural convection, the urea dissolution efficiency is low, which prolongs the time required for the solution to reach uniform concentration; at the same time, local concentration gradient is easily formed in the tank, resulting in uneven spatial distribution of urea solution concentration supplied to the denitration system. This concentration fluctuation not only reduces the denitration reaction efficiency, but also may cause secondary pollution problems such as ammonia escape, which is difficult to meet the strict requirements of hazardous waste incineration flue gas purification on the stability and uniformity of denitration solution concentration. UTILITY MODEL CONTENTS

[0005] The utility model aims to provide a kind of denitration system based on two combustion chambers, which can solve the problems of low dissolution efficiency and uneven concentration distribution of urea solution in the dispensing tank in the prior art, and improve the denitration reaction efficiency.

[0006] The utility model discloses a following technical scheme realizes:

[0007] A kind of denitration system based on two combustion chambers, comprising: two combustion chambers;Atomizing nozzle, atomizing nozzle is installed in the inner wall of two combustion chambers;Urea liquid preparation tank, urea liquid preparation tank is installed on the outer wall of two combustion chambers, the top end of urea liquid preparation tank is equipped with urea charging port, and urea liquid preparation tank is equipped with water inlet;Infusion tube, one end of infusion tube is connected atomizing nozzle, the other end of infusion tube is connected in the inside of urea liquid preparation tank, and centrifugal pump is installed on infusion tube;Motor, motor is installed at the bottom of urea liquid preparation tank;Hollow structure's rotating shaft, one end of rotating shaft is connected first motor, the other end of rotating shaft passes through urea charging port, and the side wall of rotating shaft is equipped with multiple filter feed holes along extension direction, and the outer wall of rotating shaft is equipped with multiple mixing paddles along extension direction.

[0008] Further, in the utility model, the above-mentioned further include filter material inner tube, the top end of filter material inner tube is equipped with urea inlet, and filter material inner tube can be inserted into the inside of rotating shaft;The side wall of filter material inner tube is equipped with multiple flow guide filter holes along extension direction;Multiple flow guide filter holes can be respectively aligned with multiple filter feed holes.

[0009] Further, in the utility model, the outer wall of the top end of the above-mentioned filter material inner tube is provided with multiple clamping bosses along the circumferential direction;The inner wall of the top end of rotating shaft is equipped with multiple clamping grooves along the circumferential direction, and multiple clamping grooves can be respectively matched with multiple clamping bosses.

[0010] Further, in the utility model, the above-mentioned further include sealing cover, and the inner wall of sealing cover is connected with the outer wall of rotating shaft through thread, and sealing cover can position the axial displacement of filter material inner tube.

[0011] Further, in the utility model, the connecting place of the above-mentioned urea liquid preparation tank and infusion tube is equipped with filter screen.

[0012] Further, in the utility model, the outer wall of the above-mentioned infusion tube is covered with heat preservation layer.

[0013] Compared with prior art, the utility model has the following advantages and beneficial effects:

[0014] 1. The utility model can break the limitation of natural diffusion by introducing forced mixing means, greatly accelerate the dispersion speed of urea molecules in water, thereby significantly shorten the time required for complete dissolution of urea.

[0015] 2.The utility model discloses can effectively intercept larger urea particles and impurities, in the maintenance stage, operating personnel can directly take out the filter material inner cylinder whole, and the impurities accumulated in the inside are cleaned quickly.This design significantly reduces the complexity and difficulty of maintenance work, reduces the downtime maintenance time, thereby effectively improving the continuous operation ability of the liquid preparation system, and guaranteeing the overall operation efficiency of the denitration system. BRIEF DESCRIPTION OF DRAWINGS

[0016] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present utility model and are incorporated in and constitute a part of this application, illustrate embodiments of the present utility model and do not limit the present utility model. In the drawings:

[0017] Figure 1 It is a first perspective view of a denitration system based on two combustion chambers;

[0018] Figure 2 It is Figure 1 It is an enlarged view of A in the middle;

[0019] Figure 3 It is a second perspective view of a denitration system based on two combustion chambers;

[0020] Figure 4 It is a longitudinal sectional view of the urea liquid preparation tank.

[0021] Markings in the drawings and corresponding names of parts:

[0022] 1-two combustion chambers, 2-urea liquid preparation tank, 3-motor, 4-water inlet, 5-rotating shaft, 6-sealing cover, 7-urea inlet, 8-engaging groove, 9-connection boss, 10-filter feed hole, 11-flow guide filter hole, 12-mixing paddle, 13-liquid conveying pipe, 14-centrifugal pump, 15-urea feeding port, 16-urea inlet, 17-filter screen. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the present utility model more clear, specific embodiments and the drawings will be further described, the schematic embodiment and the description of the present utility model are only used to explain the present utility model, and do not limit the present utility model.

[0024] In order to more clearly explain the embodiments of the present utility model, the hazardous waste incineration and flue gas purification process will be explained as follows:

[0025] Pretreatment process: hazardous waste is collected and transported by transport vehicles to disposal center, and may be classified, crushed, stirred and other pretreatment operations, to ensure the stability and uniformity of the subsequent incineration process.

[0026] Incineration: Pretreated hazardous waste is fed into the incinerator. First, in a combustion chamber, the material is thermally decomposed under medium temperature and oxygen-deficient conditions, and large volatile molecules are converted into small flammable gas molecules. Then, these gases enter the secondary combustion chamber. The secondary combustion chamber adopts a vertical structure and the flue gas flows from top to bottom. The operating temperature is maintained at 850-1000°C, and the flue gas residence time in the secondary combustion chamber is greater than 2 seconds to ensure complete decomposition and combustion of harmful gases, achieving harmless treatment of hazardous waste.

[0027] Flue gas denitration: In the secondary combustion chamber, the prepared urea solution is sprayed into the high-temperature flue gas. The urea solution is delivered by a high-pressure pump to the spray head in the secondary combustion chamber. In the high-temperature environment, urea rapidly decomposes to produce ammonia, which reacts with nitrogen oxides in the flue gas to produce nitrogen and water, thereby removing nitrogen oxides from the flue gas and reducing pollutant emissions.

[0028] Boiler heat recovery: After denitration, the flue gas enters the boiler system. The flue gas waste heat is used to heat the boiler feedwater, increasing the boiler feedwater temperature, improving the boiler thermal efficiency, and reducing fuel consumption. Subsequently, the flue gas enters the air preheater and exchanges heat with cold air, heating the cold air and sending it into the boiler combustion area to promote complete combustion of the fuel, reduce the exhaust gas temperature, reduce the exhaust gas heat loss, and improve energy utilization.

[0029] Subsequent flue gas purification: After boiler heat recovery, the flue gas temperature is significantly reduced, and then enters the quenching acid removal tower. In the tower, the cooling liquid is an alkaline sodium hydroxide solution, which is pressurized by a corrosion-resistant pump and sprayed through the spray head to form a mist, which reacts with the acidic gases in the flue gas to form corresponding salts, while rapidly cooling the flue gas to prevent the formation of dioxins. After that, the flue gas enters the bag filter to remove dust particles, and may also pass through an activated carbon bed to adsorb residual dioxins, heavy metals, odors, and other harmful substances, ensuring that the flue gas meets the emission standards. Finally, the purified flue gas is drawn by the induced draft fan and discharged into the atmosphere through the chimney.

[0030] Embodiment

[0031] Please refer to Figure 1 and Figure 4 . The embodiment of the utility model provides a kind of denitration system based on secondary combustion chamber 1. The system is mainly composed of secondary combustion chamber 1, atomizing nozzle, urea solution preparation tank 2, liquid conveying pipe 13, motor 3 and hollow rotating shaft 5. Atomizing nozzle is embedded in the inner wall of secondary combustion chamber 1, and atomizing nozzle can uniformly atomize and spray urea solution into the high-temperature flue gas of secondary combustion chamber 1, to realize sufficient contact and reaction with nitrogen oxides. Urea solution preparation tank 2 is installed on the outer wall of secondary combustion chamber 1 as the core component of solution preparation, and urea solution preparation tank 2 is provided with urea charging port 15 at top end, and water inlet 4 is formed at top end of tank body, and urea charging port 15 and water inlet 4 are respectively used for solid urea addition and solvent water injection.

[0032] The one end of the infusion tube 13 is connected with the atomizing nozzle, and the other end of the infusion tube 13 penetrates through the side wall of the second combustion chamber 1 and then extends into the bottom of the urea solution preparation tank 2. The centrifugal pump 14 assembled on the infusion tube 13 can control the delivery flow and pressure of the urea solution, so as to ensure that the urea solution is stably delivered to the atomizing nozzle. The motor 3 is installed at the bottom of the urea solution preparation tank 2, and the output shaft of the motor 3 is coaxially connected with the hollow rotating shaft 5. The rotating shaft 5 extends upward from the bottom of the urea solution preparation tank 2, penetrates through the urea solution preparation tank 2 and passes through the urea feeding port 15. A plurality of filtering feeding holes 10 are uniformly distributed on the side wall of the rotating shaft 5 in the axial direction. A plurality of mixing paddles 12 are arranged on the outer wall of the rotating shaft 5. The rotating shaft 5 is provided with a mechanical seal structure at the position penetrating through the solution preparation tank, so as to prevent the solution from leaking.

[0033] During the system operation, the operator adds water to the urea solution preparation tank 2 through the water inlet 4, and simultaneously adds solid urea from the top end of the rotating shaft 5. In order to ensure the operation safety and the environmental cleanness during the preparation of the urea solution, the detachable sealing structure can be used at the water inlet 4 and the top end of the rotating shaft 5. After the urea enters the inside of the rotating shaft 5, the water in the solution preparation tank penetrates into the rotating shaft 5 through the filtering feeding holes 10 and contacts with the urea. The urea is dispersed and released into the solution through the porous shaft wall, and simultaneously the motor 3 drives the rotating shaft 5 to rotate, so that the mixing paddles 12 drive the solution to form strong convection and turbulent flow, so as to quickly and uniformly disperse the urea and significantly improve the mixing efficiency. The urea in the rotating shaft 5 moves downward under the action of gravity, and forms relative motion with the urea solution circulating outside the rotating shaft 5. The solution continuously washes the surface of the urea particles, accelerates the dissolution process, and ensures stable and efficient dissolution. In this process, the filtering feeding holes 10 effectively intercept the large particles of urea and impurities which are not completely dissolved, so as to prevent them from entering the urea solution preparation tank 2, and further prevent the atomizing nozzle from being blocked, so as to ensure the long-term stable operation of the system. The prepared urea solution with a concentration of about 10% is delivered to the atomizing nozzle through the infusion tube 13 under the action of the centrifugal pump 14, and is sprayed into the second combustion chamber 1 in the form of mist, so as to react with the nitrogen oxides in the high-temperature flue gas, and finally realize efficient denitrification.

[0034] For example, the inner wall of the urea solution preparation tank 2 can be provided with an electric heating pipe. The two ends of the electric heating pipe are connected with the intelligent power control system through high-temperature-resistant insulated wires, so as to ensure stable transmission of electric energy and electrical safety. The electric heating pipe maintains a safe distance from the motion area of the mixing paddles 12, so as to eliminate the risk of mechanical interference. During the system operation, the electric heating pipe strictly controls the temperature of the urea solution in the urea best dissolution temperature range (20 to 40℃) according to the real-time feedback data of the temperature sensor. This can significantly improve the diffusion rate of urea molecules, accelerate the dissolution process, effectively inhibit the crystallization and precipitation of urea, and ensure the stability of the solution concentration, so as to provide a strong guarantee for the efficient and reliable operation of the denitrification system of the second combustion chamber 1.

[0035] In some embodiments of the present application, a high-precision urea solution concentration sensor is installed inside the urea solution preparation tank 2 to sense the real-time changes in the concentration of the urea solution. The data collected by the probe is processed by the signal processing circuit to filter and amplify, and then converted into standard digital / analog signals and transmitted to the system control unit. The shell of the urea solution concentration sensor is made of corrosion-resistant and wear-resistant special engineering plastics or stainless steel, effectively resisting chemical corrosion of the urea solution and ensuring long-term stable operation.

[0036] For reference Figure 4 In some embodiments of the present application, the filter inner cylinder is a hollow cylindrical structure, with a urea inlet 7 at the top and a sealed structure at the bottom. The side wall of the filter inner cylinder is provided with a plurality of flow guide filter holes 11 along the extension direction. The filter inner cylinder can be inserted into the inside of the rotating shaft 5, and the filter inner cylinder is tightly fitted with the hollow cavity of the rotating shaft 5. When the filter inner cylinder is completely embedded in place, the flow guide filter holes 11 are precisely aligned with the filter feed holes 10. After the urea particles enter through the urea inlet 7, they can diffuse to the outside of the rotating shaft 5 through the flow guide filter holes 11 and the filter feed holes 10 in turn. The flow guide filter holes 11 can intercept larger urea particles and impurities inside the filter inner cylinder. During maintenance, the operator can pull out the filter inner cylinder as a whole and clean the impurities inside the filter inner cylinder. This significantly reduces the complexity of maintenance and effectively improves the continuous operation capability of the preparation system.

[0037] For reference Figure 2 and Figure 4 In some embodiments of the present application, the outer wall of the top end of the filter inner cylinder is designed in a circumferential array, with a plurality of clamping bosses 9 evenly distributed. The inner wall of the top end of the rotating shaft 5 is provided with a corresponding clamping groove 8.

[0038] During assembly, when the filter inner cylinder is inserted axially along the rotating shaft 5, the plurality of clamping bosses 9 are gradually embedded along the plurality of clamping grooves 8, and when they are completely in place, the clamping bosses 9 and the clamping grooves are radially locked and circumferentially limited. This interference fit clamping mechanism not only allows the rotating shaft 5 to drive the filter inner cylinder to rotate synchronously through torque transmission, but also ensures that the flow guide filter holes 11 of the filter inner cylinder side wall and the filter feed holes 10 of the rotating shaft 5 are always aligned through mechanical positioning. This ensures the orderly diffusion of urea particles through the flow guide filter holes 11 and the filter feed holes 10, avoiding the risk of blockage or uneven mixing caused by misalignment, and significantly improving the reliability and operating efficiency of the preparation system.

[0039] In some embodiments of the present application, the inner wall of the sealing cover 6 is machined with an internal thread, and the outer wall of the top end of the rotating shaft 5 is also provided with a matching external thread, which constitutes a threaded pair connection. The operator only needs to rotate the sealing cover 6 and the top end of the rotating shaft 5 clockwise to achieve firm and tight connection. The sealing cover 6 can constrain the filter material inner cylinder inside the rotating shaft 5, effectively eliminating the risk of axial movement of the filter material inner cylinder caused by centrifugal force or vibration, ensuring that the side wall flow guide filter hole 11 of the filter material inner cylinder and the filter material hole 10 of the rotating shaft 5 are always coaxially aligned, and maintaining the stability and smoothness of the urea particle conveying channel.

[0040] Please refer to Figure 4 In some embodiments of the present application, the urea solution tank 2 is provided with a liquid outlet, and a liquid outlet pipe 13 is in communication with the urea solution tank 2 through the liquid outlet. The filter screen 17 installed on the liquid outlet serves as the secondary filtration line of the entire system, which can intercept various impurities and larger particles in the solution. These impurities may be caused by incomplete dissolution of urea lumps during urea dissolution, or fine particles mixed from the external environment. The filter screen 17 can effectively block impurities and larger particles in the urea solution tank 2, and only allow pure urea solution to be smoothly delivered to the atomizing nozzle.

[0041] Further, in the present application, the outer wall of the liquid outlet pipe 13 is covered with a heat preservation layer (polyurethane foam, rock wool, etc.), which can control the temperature fluctuation of the urea solution in the liquid outlet pipe 13 within ±2℃, effectively avoiding the problem of urea solution crystallization or concentration fluctuation caused by environmental temperature change, and providing reliable guarantee for the stable operation of the downstream atomizing nozzle.

[0042] The above specific embodiments further illustrate the purpose, technical solutions and advantages of the present application. It should be understood that the above description is only a specific embodiment of the present application and does not limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A denitration system based on two combustion chambers (1), characterized in that, It comprises: a double combustion chamber (1); an atomizing nozzle installed on the inner wall of the double combustion chamber (1); a urea solution preparation tank (2) installed on the outer wall of the double combustion chamber (1), the top end of the urea solution preparation tank (2) is provided with a urea feeding port (15), and the urea solution preparation tank (2) is provided with a water feeding port (4); a liquid delivery pipe (13), one end of the liquid delivery pipe (13) is connected to the atomizing nozzle, and the other end of the liquid delivery pipe (13) is connected to the inside of the urea solution preparation tank (2), and a centrifugal pump (14) is installed on the liquid delivery pipe (13); a motor (3) installed at the bottom of the urea solution preparation tank (2); a hollow rotating shaft (5), one end of the rotating shaft (5) is connected to the first motor (3), the other end of the rotating shaft (5) passes through the urea feeding port (15), the side wall of the rotating shaft (5) is provided with a plurality of filter feeding holes (10) in the extension direction, and the outer wall of the rotating shaft (5) is provided with a plurality of mixing paddles (12) in the extension direction.

2. The denitration system based on the two combustion chambers (1) according to claim 1, characterized in that, It also comprises a filter inner cylinder, the top end of the filter inner cylinder is provided with a urea inlet (7), and the filter inner cylinder can be inserted into the inside of the rotating shaft (5); the side wall of the filter inner cylinder is provided with a plurality of flow guide filter holes (11) in the extension direction; a plurality of flow guide filter holes (11) can be aligned with a plurality of filter feeding holes (10) respectively.

3. The denitration system based on the two combustion chambers (1) according to claim 2, characterized in that, the outer wall of the top end of the filter inner cylinder is provided with a plurality of clamping bosses (9) in the circumferential direction; the inner wall of the top end of the rotating shaft (5) is provided with a plurality of clamping grooves (8) in the circumferential direction, and a plurality of clamping grooves (8) can be matched with a plurality of clamping bosses (9) respectively.

4. The denitration system based on the two combustion chambers (1) according to claim 3, characterized in that, It also comprises a sealing cover (6), the inner wall of the sealing cover (6) is connected with the outer wall of the rotating shaft (5) through threads, and the sealing cover (6) can position the axial displacement of the filter inner cylinder.

5. The De-NOx system based on two combustion chambers (1) according to any one of claims 1 to 4, characterized in that, A filter screen (17) is installed at the connection between the urea solution preparation tank (2) and the liquid delivery pipe (13).

6. The denitration system based on the dual combustion chamber (1) according to any one of claims 1 to 4, characterized in that, The outer wall of the liquid delivery pipe (13) is covered with a heat preservation layer.

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