Circulating urea hydrolysis denitration system

Abstract

The utility model discloses a circulating urea hydrolysis denitration system, which belongs to the technical field of urea hydrolysis and comprises a urea hydrolyzer body, a circulating mechanism and a denitration mechanism. Wherein the circulating mechanism comprises a liquid outlet pipe, and the liquid outlet pipe is communicated with the urea hydrolyzer body; the urea storage box is arranged at the end, away from the end connected with the urea hydrolyzer body, of the liquid outlet pipe; one end of the liquid inlet pipe is communicated with the urea storage box; the water pump is arranged on the liquid inlet pipe, and the water pump is communicated with the liquid inlet pipe. According to the urea hydrolyzer, the urea storage box is arranged, so that a urea solution in the urea hydrolyzer body flows into the urea storage box through the liquid outlet pipe to be stored, and when the urea hydrolyzer needs to be used, the urea solution in the urea storage box flows back into the urea hydrolyzer body through the liquid inlet pipe; the defect of loss caused by direct discharge of the urea solution during equipment maintenance is overcome, and the technical effect of cyclic utilization of the urea solution is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of urea hydrolysis, in particular to a circulating urea hydrolysis denitration system. Background Art

[0002] The production of ammonia by urea hydrolysis is widely used in current coal-fired power plants with large installed capacities. Urea solution is hydrolyzed in a hydrolysis reactor to produce NH3, H2O, and CO2. The product gas is then mixed with air and sprayed into the flue gas as a reducing agent for flue gas denitration, and reacts with the exhaust gas discharged from the boiler and is discharged again to meet environmental protection requirements. During the denitration reaction process, after the equipment fails, maintenance is required, and usually only the urea solution in the hydrolyzer can be discharged, which causes a large loss of urea solution and also produces high-concentration urea-containing wastewater. Content of the Utility Model

[0003] To solve the above problems, the utility model provides a circulating urea hydrolysis denitration system, including:

[0004] A urea hydrolysis reactor body for injecting urea solution for hydrolysis;

[0005] A circulation mechanism connected to the urea hydrolysis reactor body, and the urea solution in the urea hydrolysis reactor body flows out to the circulation mechanism for storage and then flows back into the urea hydrolysis reactor body again;

[0006] A denitration mechanism connected to the urea hydrolysis reactor body, and the product gas generated after the hydrolysis of the urea solution reacts with the flue gas discharged from the boiler in the denitration mechanism;

[0007] Wherein, the circulation mechanism includes:

[0008] A liquid outlet pipe connected to the urea hydrolysis reactor body, and the urea solution can flow out of the urea hydrolysis reactor body through the liquid outlet pipe;

[0009] A urea storage tank arranged at one end of the liquid outlet pipe far from the connection with the urea hydrolysis reactor body, and the urea storage tank is connected to the liquid outlet pipe;

[0010] A liquid inlet pipe, one end of the liquid inlet pipe is connected to the urea storage tank, and the other end of the liquid inlet pipe is connected to the urea hydrolysis reactor body;

[0011] A water pump connected to the liquid inlet pipe, and the water pump is located at the connection of the liquid inlet pipe and the urea storage tank.

[0012] Optionally, the circulation mechanism further includes:

[0013] Two first valves, both of the two first valves are arranged on the liquid outlet pipe and are respectively located at two ends of the liquid outlet pipe;

[0014] Two second valves, both of the two second valves are arranged on the liquid inlet pipe and are respectively located at two ends of the liquid inlet pipe;

[0015] A check valve, the check valve is arranged on the liquid inlet pipe to prevent the urea solution from flowing back in the liquid inlet pipe.

[0016] Optionally, the denitration mechanism includes:

[0017] An ammonia mixer, the ammonia mixer is connected to the urea hydrolyzer body, and the product gas generated in the urea hydrolyzer body can be mixed with air through the ammonia mixer;

[0018] A denitration reactor, the denitration reactor is connected to the ammonia mixer and is used for spraying the ammonia-air mixture in the ammonia mixer to mix and react with the flue gas generated by the boiler;

[0019] An economizer, the economizer is connected to the denitration reactor, and the economizer is used for reducing the temperature of the exhaust gas in the tail flue of the boiler;

[0020] An air preheater, the air preheater is connected to the denitration reactor and is used for improving the heat exchange performance of the boiler and reducing the energy consumption.

[0021] Optionally, a desuperheater and pressure reducer is further arranged at the connection between the liquid outlet pipe and the urea storage tank.

[0022] Optionally, a third valve is arranged between the ammonia mixer and the denitration reactor, a flow meter is arranged between the economizer and the denitration reactor, and the flow meter is in telecommunication connection with the third valve through an external controller.

[0023] Optionally, a flue gas inlet mechanism is further arranged on the denitration reactor;

[0024] Wherein, the flue gas inlet mechanism includes:

[0025] A flue, the flue is arranged on the denitration reactor, and the flue is a curved spiral structure;

[0026] A flow deflector, the flow deflector is arranged at the bottom end of the flue, the top end of the flow deflector is communicated with the flue, and the bottom end of the flow deflector is communicated with the top end of the denitration reactor;

[0027] A plurality of guide vanes, a plurality of the guide vanes are arranged on the flow deflector, and all the plurality of guide vanes are curved plate-like structures.

[0028] Optionally, a steam pipeline is also connected to the liquid outlet pipe.

[0029] Optionally, thermometers and pressure gauges are provided on both the liquid inlet pipe and the liquid outlet pipe.

[0030] By adopting the above technical solutions, the present utility model mainly has the following technical effects:

[0031] In the present utility model, by providing a urea storage tank, the urea solution in the urea hydrolyzer body flows through the liquid outlet pipe to the urea storage tank for storage, and when in need of use, the urea solution in the urea storage tank flows back to the urea hydrolyzer body through the liquid inlet pipe, solving the drawback of direct discharge of the urea solution during equipment maintenance, and achieving the technical effect of recycling the urea solution. Description of the Drawings

[0032] Figure 1 is a schematic structural diagram of a circulating urea hydrolysis denitration system of the present utility model;

[0033] Figure 2 is a schematic structural diagram of the denitration mechanism of a circulating urea hydrolysis denitration system of the present utility model;

[0034] Figure 3 is a schematic structural diagram of the flue gas inlet mechanism of a circulating urea hydrolysis denitration system of the present utility model;

[0035] Figure 4 is a sectional view schematic structural diagram of the flue gas inlet mechanism of a circulating urea hydrolysis denitration system of the present utility model.

[0036] Among them, the meanings of the reference numerals are as follows:

[0037] 1. Urea hydrolyzer body;

[0038] 2. Circulation mechanism; 21. Liquid outlet pipe; 211. Desuperheating and pressure reducing device; 212. Steam pipeline; 22. Urea storage tank; 23. Liquid inlet pipe; 24. Water pump; 25. First valve; 26. Second valve; 27. Check valve; 28. Thermometer; 29. Pressure gauge;

[0039] 3. Denitration mechanism; 31. Ammonia mixer; 32. Denitration reactor; 321. Flue gas inlet mechanism; 3211. Flue; 3212. Flow guide cover; 3213. Guide vane; 33. Economizer; 34. Air preheater; 35. Third valve; 36. Flowmeter. Detailed Embodiments

[0040] To enable those skilled in the art to better understand the solution of the present utility model, the technical solutions in the embodiments of the present utility model will be clearly and completely described below in conjunction with the accompanying drawings in the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0041] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present utility model. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0042] Embodiment:

[0043] Please refer to Figures 1-4 , the present utility model provides a circulating urea hydrolysis denitration system. In practical applications, to solve the problem of losses caused by the direct discharge of urea solution during equipment maintenance, it includes a urea hydrolyzer body 1, a circulation mechanism 2 connected to the urea hydrolyzer body 1, and a denitration mechanism 3 connected to the urea hydrolyzer body 1.

[0044] Specifically, the urea hydrolyzer body 1 is used to inject urea solution for hydrolysis. The circulation mechanism 2 is connected to the urea hydrolyzer body 1. After the urea solution in the urea hydrolyzer body 1 is discharged, it can be collected and stored through the circulation mechanism 2 and then refluxed into the urea hydrolyzer body 1 for reuse. The denitration mechanism 3 is connected to the urea hydrolyzer body 1. After the product gas generated after hydrolysis in the urea hydrolyzer enters the denitration mechanism 3, it can be mixed with the flue gas discharged from the boiler, causing the denitration reaction of the flue gas discharged from the boiler.

[0045] Among them, the circulation mechanism 2 includes a liquid outlet pipe 21 communicated with the urea hydrolyzer body 1, a urea storage tank 22 communicated with the liquid outlet pipe 21, a liquid inlet pipe 23 connected to the urea storage tank 22, and a water pump 24 communicated with the liquid inlet pipe 23. The liquid outlet pipe 21 is arranged at the bottom end of the urea hydrolyzer body 1 and is communicated with the urea hydrolyzer body 1, and the urea solution in the urea hydrolyzer body 1 can flow out quickly through the liquid outlet pipe 21. The urea storage tank 22 is arranged at one end of the liquid outlet pipe 21 far from the connection with the urea hydrolyzer body 1, and one side of the urea storage tank 22 is communicated with the liquid outlet pipe 21. The urea solution discharged from the urea hydrolyzer body 1 can flow into the urea storage tank 22 through the liquid outlet pipe 21 for storage. Preferably, a temperature and pressure reducer 211 is further arranged at the connection between the liquid outlet pipe 21 and the urea storage tank 22. The temperature and pressure reducer 211 is used to reduce the temperature and pressure of the urea solution flowing out of the urea hydrolyzer body 1 into the liquid outlet pipe 21 to prevent the urea solution from flashing when flowing into the urea storage tank 22. One end of the liquid inlet pipe 23 is communicated with the urea storage tank 22, and the other end of the liquid inlet pipe 23 is communicated with the urea hydrolyzer body 1. The urea solution flowing out of the urea hydrolyzer body 1 stored in the urea storage tank 22 can flow back into the urea hydrolyzer body 1 again through the drainage of the liquid inlet pipe 23 to achieve recycling. The water pump 24 is communicated with the liquid inlet pipe 23, and the water pump 24 is located at the connection between the liquid inlet pipe 23 and the urea storage tank 22. The water pump 24 pumps the urea solution in the liquid inlet pipe 23 to accelerate the flow rate of the urea solution in the liquid inlet pipe 23, thereby accelerating the speed of the urea solution entering the urea hydrolyzer body 1.

[0046] In this embodiment, the circulation mechanism 2 further includes two first valves 25, two second valves 26 and a check valve 27. Specifically, the two first valves 25 are both arranged on the liquid outlet pipe 21 and are respectively located at both ends of the liquid outlet pipe 21, that is, the two first valves 25 are respectively arranged at the connection between the liquid outlet pipe 21 and the urea hydrolyzer body 1 and the connection between the liquid outlet pipe 21 and the urea storage tank 22. By controlling the opening and closing of the two first valves 25, the flow of the urea solution in the liquid outlet pipe 21 can be controlled. For example, when the urea hydrolyzer body 1 is operating normally, the two first valves 25 remain closed, and the urea solution in the urea hydrolyzer body 1 will not flow out. The two second valves 26 are both arranged on the liquid inlet pipe 23 and are respectively located at both ends of the liquid inlet pipe 23, that is, the two second valves 26 are respectively arranged at the connection between the liquid inlet pipe 23 and the urea storage tank 22 and the connection between the liquid inlet pipe 23 and the urea hydrolyzer body 1. By controlling the opening and closing of the two second valves 26, the flow of the urea solution in the liquid inlet pipe 23 can be controlled. For example, when the urea hydrolyzer body 1 is operating normally, the two second valves 26 remain open, and the urea solution in the urea storage tank 22 can smoothly flow into the urea hydrolyzer body 1 from the urea storage tank 22. The check valve 27 is arranged on the liquid inlet pipe 23 to prevent the urea solution from flowing back when discharged into the liquid inlet pipe 23 and improve the safety of the liquid inlet pipe 23.

[0047] In this embodiment, when the equipment needs to be inspected and repaired, the urea hydrolyzer is closed to stop hydrolyzing the urea solution, and the operation of the denitration mechanism 3 is stopped. At this time, the two first valves 25 are opened, so that the urea solution in the urea hydrolyzer body 1 flows into the urea storage tank 22 through the liquid outlet pipe 21 for temporary storage. After the inspection and repair are completed, the two second valves 26 on the liquid inlet pipe 23 are opened, and the water pump 24 is started to pump the urea solution temporarily stored in the urea storage tank 22 into the urea hydrolyzer body 1 through the liquid inlet pipe 23, solving the disadvantage of direct discharge of the urea solution during equipment maintenance and achieving the technical effect of recycling the urea solution.

[0048] In some preferred embodiments, a steam pipeline 212 is further connected to the liquid outlet pipe 21. The plant steam enters the liquid outlet pipe 21 through the steam to clean the circulation mechanism 2, prevent the urea solution in the circulation mechanism from crystallizing and causing blockage, and at the same time avoid the residue of the urea solution in the pipeline.

[0049] Preferably, a thermometer 28 and a pressure gauge 29 are provided on both the liquid inlet pipe 23 and the liquid outlet pipe 21. The thermometer 28 is used to measure the temperature of the urea solution in the pipeline to ensure that the solution is within a suitable working temperature range. The pressure gauge 29 is used to measure the pressure in the pipeline. For example, when the pressure in the pipeline is too high, there is a problem of blockage in the pipeline, so that the staff can discover the problem in time and take corresponding measures to avoid accidents.

[0050] Please refer to Figures 1-2 In this embodiment, the denitration mechanism 3 includes an ammonia mixer 31 and a denitration section. The ammonia mixer 31 is connected to the urea hydrolyzer body 1. After the product gas generated by the hydrolysis of the urea solution in the urea hydrolyzer body 1 enters the ammonia mixer 31, it can be mixed with air to form an ammonia-air mixture. For example, the ammonia mixer 31 realizes the full mixing of ammonia and air through jet mixing, multi-tube arrangement, fluid cutting and shearing, and pressure and flow control. The denitration reactor 32 is connected to the ammonia mixer 31 and is used to mix and react the ammonia-air mixture ejected from the ammonia mixer 31 with the flue gas discharged from the boiler. For example, in the denitration reactor 32, a reducing agent (such as ammonia) is evenly sprayed into the flue gas through a spraying system and is mixed with the flue gas entering the denitration reactor 32 through air flow disturbance, turbulence, etc. When the mixed gas passes through the catalyst layer, under the action of the catalyst, a chemical reaction occurs between the reducing agent and the flue gas. The economizer 33 is connected to the denitration reactor 32 and is used to reduce the temperature of the exhaust gas in the tail flue of the boiler. For example, a heat exchange structure (such as a serpentine tube) is provided inside the economizer to absorb the waste heat of the flue gas and improve the energy utilization efficiency. The air preheater 34 is connected to the denitration reactor 32 and is used to improve the heat exchange performance of the boiler and reduce energy consumption. For example, the gas generated after the reaction carries a large amount of heat. When it flows through the heat exchange elements (such as tube bundles, fins, etc.) of the air preheater, it transfers the heat to these elements to achieve heat exchange and gradually reduce the gas temperature. Among them, a third valve 35 is provided between the ammonia mixer 31 and the denitration reactor 32 to control the flow rate of ammonia entering the denitration reactor 32. A flow meter 36 is provided between the economizer 33 and the denitration reactor 32, and the flow meter 36 is connected to the third valve 35 through an external controller in a telecommunication manner. That is, while the flow meter 36 detects the flue gas emission volume of the boiler, it feeds back the detected data to the controller, and the controller controls the opening degree of the third valve 35, thereby controlling the flow rate of the ammonia-air mixture entering the denitration reactor 32 to ensure that a certain ratio is formed between the ammonia-air mixture and the flue gas discharged from the boiler, making the denitration reaction more complete. For example, when the flue gas flow rate discharged from the boiler reaches the set threshold, the flow meter 36 feeds back the detection data to the controller, and the controller controls the third valve 35 to open completely, so that the ammonia-air mixture enters the denitration reactor 32 in the largest amount.

[0051] Preferably, the flowmeter 36 is a thermal gas mass flowmeter 36, which determines the mass flow rate of the gas by measuring the heat exchange relationship between the heating element and the fluid. It has the characteristics of high precision, fast response, wide range ratio and high reliability, and is suitable for the measurement of various gas flows.

[0052] Please refer to Figures 3-4 , in some preferred embodiments, to facilitate the faster discharge efficiency of the flue gas and ammonia-air mixture into the denitration reactor 32, a flue gas inlet mechanism 321 is further provided on the denitration reactor 32. Among them, the flue gas inlet mechanism 321 includes a flue 3211, a deflector hood 3212 and guide vanes 3213. Specifically, the flue 3211 is arranged on the denitration reactor 32 through a bracket for the flue gas to enter the denitration reactor 32, and the flue 3211 is a curved spiral structure, which can reduce the generation of eddy currents and turbulence in the flue 3211 and improve the flow efficiency of the flue gas. The deflector hood 3212 is arranged at the bottom end of the flue 3211, the top end of the deflector hood 3212 is communicated with the flue 3211, and the bottom end of the deflector hood 3212 is communicated with the top end of the denitration reactor 32. The flue gas entering the flue 3211 can be concentrated through the restraint of the deflector hood 3212 and then enter the denitration reactor 32. To improve the flue gas circulation efficiency, a plurality of guide vanes 3213 are further provided on the deflector hood 3212. The plurality of guide vanes 3213 are uniformly distributed in a fan shape on the inner wall of the deflector hood 3212, and the plurality of guide vanes 3213 are all curved plate-like structures, so that eddy currents are formed after the flue gas passes through the deflector hood 3212, and the circulation efficiency is accelerated.

[0053] Finally, it should be noted that: what is disclosed in the embodiments of the present invention is only the preferred embodiments of the present invention, which are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A circulating urea hydrolysis denitrification system, characterized in that: include: A urea hydrolyzer body (1), wherein the urea hydrolyzer body (1) is used to inject urea solution for hydrolysis; A circulation mechanism (2), the circulation mechanism (2) being in communication with the urea hydrolyzer body (1), wherein the urea solution in the urea hydrolyzer body (1) flows out to the circulation mechanism (2) for storage and then flows back into the urea hydrolyzer body (1); A denitration mechanism (3), the denitration mechanism (3) being connected to the urea hydrolyzer body (1), wherein the product gas generated after the hydrolysis of the urea solution reacts with the flue gas discharged from the boiler in the denitration mechanism (3); Wherein, the circulation mechanism (2) comprises: a liquid outlet pipe (21), the liquid outlet pipe (21) being in communication with the urea hydrolyzer body (1), and the urea solution flows out of the urea hydrolyzer body (1) through the liquid outlet pipe (21); a urea storage tank (22), the urea storage tank (22) being arranged at an end of the liquid outlet pipe (21) away from the end connected to the urea hydrolyzer body (1), and the urea storage tank (22) being in communication with the liquid outlet pipe (21); a liquid inlet pipe (23), one end of which is in communication with the urea storage tank (22), and the other end of which is in communication with the urea hydrolyzer body (1); A water pump (24), the water pump (24) is connected to the liquid inlet pipe (23), and the water pump (24) is located at the connection between the liquid inlet pipe (23) and the urea storage tank (22).

2. A circulating urea hydrolysis and denitrification system according to claim 1, characterized in that: The circulation mechanism (2) further comprises: Two first valves (25), both of which are arranged on the liquid outlet pipe (21) and are respectively located at two ends of the liquid outlet pipe (21); Two second valves (26), the two second valves (26) are both arranged on the liquid inlet pipe (23), and are respectively located at two ends of the liquid inlet pipe (23); A check valve (27) is arranged on the liquid inlet pipe (23) to prevent the urea solution from flowing back in the liquid inlet pipe (23).

3. A circulating urea hydrolysis and denitrification system according to claim 1, characterized in that: The denitration mechanism (3) comprises: an ammonia mixer (31), the ammonia mixer (31) being connected to the urea hydrolyzer body (1), and the product gas generated in the urea hydrolyzer body (1) can be mixed with air through the ammonia mixer (31); A denitration reactor (32), the denitration reactor (32) being connected to the ammonia mixer (31) and used for spraying the ammonia-air mixed gas in the ammonia mixer (31) to mix and react with the flue gas generated by the boiler; An economizer (33), the economizer (33) being in communication with the denitration reactor (32), and the economizer (33) being used to reduce the temperature of exhaust gas in the boiler tail flue (3211); An air preheater (34), the air preheater (34) is connected to the denitration reactor (32) and is used to improve the heat exchange performance of the boiler and reduce energy consumption.

4. A circulating urea hydrolysis and denitrification system according to claim 1, characterized in that: A temperature and pressure reducing device (211) is also provided at the connection between the liquid outlet pipe (21) and the urea storage tank (22).

5. A circulating urea hydrolysis and denitrification system according to claim 3, characterized in that: A third valve (35) is provided between the ammonia mixer (31) and the denitration reactor (32), a flow meter (36) is provided between the economizer (33) and the denitration reactor (32), and the flow meter (36) is electrically connected to the third valve (35).

6. A circulating urea hydrolysis and denitrification system according to claim 3, characterized in that: The denitration reactor (32) is also provided with a smoke inlet mechanism (321); Wherein, the smoke inlet mechanism (321) comprises: A flue (3211), wherein the flue (3211) is disposed on the denitration reactor (32), and the flue (3211) is a curved spiral structure; A flow guide cover (3212), wherein the flow guide cover (3212) is arranged at the bottom end of the flue (3211), the top end of the flow guide cover (3212) is connected to the flue (3211), and the bottom end of the flow guide cover (3212) is connected to the top end of the denitration reactor (32); A plurality of guide vanes (3213), wherein the plurality of guide vanes (3213) are arranged on the guide cover (3212), and the plurality of guide vanes (3213) are all curved plate-like structures.

7. A circulating urea hydrolysis and denitrification system according to claim 1, characterized in that: The liquid outlet pipe (21) is also connected to a steam pipe (212).

8. A circulating urea hydrolysis and denitrification system according to claim 1, characterized in that: The liquid inlet pipe (23) and the liquid outlet pipe (21) are both provided with a thermometer (28) and a pressure gauge (29).

Images