Urea pyrolyzing furnace metering distribution system with flow balanced control function

Abstract

The utility model provides a urea pyrolyzing furnace metering distribution system with flow balance control, and belongs to the technical field of flue gas denitration urea pyrolyzing furnaces. The system comprises a urea pyrolyzing furnace, the urea pyrolyzing furnace is connected with a group of adjustable and controllable spray gun modules, each adjustable and controllable spray gun module comprises a spray gun with a spray opening formed in the urea pyrolyzing furnace, and a first inlet of each spray gun communicates with a urea solution conveying channel; and a branch pneumatic switch valve, a spray gun branch pneumatic control valve and a spray gun branch urea solution flow meter are arranged on the spray branch pipe. Based on the structural design of the multi-branch spray gun module, corresponding balance control logic and a spray gun flow PID control program are matched, so that the automatic switching of the quantity of the spray guns and the balance control of the spray flow of the metering distribution system along with the load change of the boiler can be realized; the problem that when the boiler is in low load, multiple spray guns operate at the same time, the spraying flow is low, and consequently atomization is uneven is solved, the efficiency of the urea pyrolyzing furnace is improved, and the probability that non-pyrolyzed urea forms crystals at the tail of the pyrolyzing furnace and an outlet pipeline is reduced.

Description

Technical Field

[0001] This utility model belongs to the technical field of flue gas denitrification urea pyrolysis furnace, specifically relating to a flow balance control urea pyrolysis furnace metering and distribution system. Background Technology

[0002] Urea pyrolysis ammonia production technology is widely used in domestic SCR denitrification systems due to its mature technology and high efficiency. The system process is as follows: solid urea is prepared into a urea solution with a mass fraction concentration of 45-55%, which is transported to the metering and distribution system through a urea solution circulation pump. The metering and distribution system distributes the spray gun flow according to the control logic command and then sprays the urea solution evenly into the pyrolysis furnace. At high temperature, it decomposes into NH3, H2O and CO2. This decomposition process is mixed with high temperature diluted air to generate ammonia gas with a concentration of less than 5%, which is then injected into the SCR flue gas denitrification reactor to complete the denitrification reaction.

[0003] In traditional urea pyrolysis furnace metering and distribution systems, each distribution loop uses a synchronous regulation method to adjust the urea solution flow rate. When the boiler load decreases, the spray guns remain operational, resulting in excessively low flow rates for individual spray guns. This leads to poor atomization, incomplete pyrolysis of some urea, and reduced furnace efficiency. Furthermore, the unpyrolyzed urea crystallizes at the furnace tail and outlet pipes, affecting system operation. Incomplete pyrolysis and crystal blockage may necessitate increased maintenance and cleaning frequency, increasing both manpower and material resources, potentially impacting equipment uptime and efficiency, and ultimately raising operating costs. Utility Model Content

[0004] To address the aforementioned problems in the existing technology, the purpose of this utility model is to provide a urea pyrolysis furnace metering and distribution system with balanced flow control. By making the spray gun module adjustable, the metering and distribution system can automatically switch the number of spray guns and balance the spray flow as the boiler load changes.

[0005] This utility model provides the following technical solution: a flow-balanced control urea pyrolysis furnace metering and distribution system, including a urea pyrolysis furnace, wherein a set of adjustable spray gun modules are connected to the urea pyrolysis furnace for use in controlling the delivery of urea solution into the urea pyrolysis furnace. The adjustable spray gun module includes a spray gun with the spray nozzle set inside the urea pyrolysis furnace. The first inlet of the spray gun is connected to the urea solution delivery channel through a spray branch pipe. The spray branch pipe is equipped with a branch pneumatic switch valve, a spray gun branch pneumatic regulating valve, and a spray gun branch urea solution flow meter.

[0006] Furthermore, the second inlet of the spray gun is connected to a compressed air channel for urea atomization, and its third inlet is connected to a compressed air channel for shutdown purging.

[0007] Further, the branch pneumatic switch valve, the spray gun branch pneumatic regulating valve and the spray gun branch urea solution flowmeter are sequentially arranged along the spray flow direction of the spray branch pipe.

[0008] Further, a desalted water channel is connected to the pipeline between the branch pneumatic switch valve and the spray gun branch pneumatic regulating valve.

[0009] Further, at least one adjustable spray gun module is arranged in the system.

[0010] Further, a standby spray gun assembly is connected to the urea pyrolysis furnace, and the standby spray gun assembly has the same structure as the adjustable spray gun module.

[0011] Further, a hot air channel is connected to the inlet of the urea pyrolysis furnace, and an ammonia injection grid is connected to the outlet of the urea pyrolysis furnace.

[0012] By using the above technology, compared with the prior art, the beneficial effects of the utility model are as follows:

[0013] Based on the design of the multi-branch spray gun, in combination with the set urea pneumatic regulating valve and the branch urea solution flowmeter, the corresponding balance control logic and the spray gun flow PID control program can realize the automatic switching of the metering and distribution system and the spray gun flow balance control following the change of the boiler load, improve the uneven atomization problem caused by the low spray flow of the multiple spray guns running simultaneously at the low load of the boiler, improve the efficiency of the urea pyrolysis furnace and reduce the probability of the crystallization of the unpyrolyzed urea at the tail part of the pyrolysis furnace and the outlet pipeline. BRIEF DESCRIPTION OF DRAWINGS

[0014] Fig. 1 It is a system schematic view of the utility model;

[0015] Fig. 2 It is a pyrolysis furnace spray gun flow balance control structure schematic view of the utility model;

[0016] Fig. 3 It is a spray gun flow PID control process schematic view of the utility model. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the utility model more clear and obvious, the utility model is further described in detail below by combining with the drawings and examples in the specification. It should be understood that the specific examples described herein are only used to explain the utility model, and are not used to limit the utility model.

[0018] On the contrary, the utility model covers any alternative, modification, equivalent method and scheme made on the essence and scope of the utility model defined by the claims. Further, in order to make the public have a better understanding of the utility model, some specific details are described in the following detailed description of the utility model. The utility model can also be completely understood without the description of these details for those skilled in the art.

[0019] Embodiment:

[0020] Please refer to Figs. 1-3 A flow equalization control urea pyrolysis furnace metering distribution system, including urea pyrolysis furnace 1, multiple groups of adjustable control spray gun module and spare spray gun assembly, three groups of adjustable control spray gun module and a group of spare spray gun assembly are used in the embodiment to illustrate.

[0021] Specifically, the upper inlet of urea pyrolysis furnace 1 is connected with a hot air channel, and the bottom outlet is connected with an ammonia injection grid.

[0022] Specifically, the adjustable control spray gun module includes a spray gun 5, which is arranged on the urea pyrolysis furnace 1, and the spray gun 5 is arranged in the internal cavity of the urea pyrolysis furnace 1, and the first inlet is communicated with the urea solution delivery channel through a spray branch pipe 6, and the spray branch pipe 6 is sequentially provided with a branch pneumatic on-off valve 2, a spray branch pneumatic regulating valve 3 and a spray branch urea solution flowmeter 4 along the delivery direction of the urea solution; and the spray branch pipe 6 is communicated with the desalted water delivery channel through a pipeline between the branch pneumatic on-off valve 2 and the spray branch pneumatic regulating valve 3.

[0023] Specifically, the second and third inlets of the spray gun 5 are communicated with the compressed air delivery channel, respectively for urea atomization and spray gun 5 shutdown purging.

[0024] When the waste heat boiler 100% BMCR load runs, the required 50% urea solution injection amount of the pyrolysis furnace corresponding to the SCR reactor is calculated according to the denitration inlet NO X Concentration and denitration efficiency, taking 120kg / h as an example, the spray gun is 3 for 1 spare, and the rated flow of the spray gun is 50kg / h;

[0025] The working steps of the system of the embodiment are as follows:

[0026] S1, the pyrolysis furnace system meets the operation condition and has been put into automatic operation state, enters the low load operation mode: according to the denitration inlet NO XThe concentration and denitrification efficiency are calculated based on the total amount of urea solution N required for the pyrolysis furnace corresponding to the SCR reactor. The value of N is then assessed. If the total urea solution injection amount is 40 ≤ N ≤ 80 kg / h, a 60-second delay is applied, and the pyrolysis furnace enters a low-load operation mode, using a two-spray-gun operation mode. The calculated urea solution injection amount for a single spray gun 5 is N / 2 kg / h, ensuring the flow rate of a single spray gun 5 is controlled within the optimal atomization range. The spray gun operation sequence is as follows: Simultaneously open the branch pneumatic switch valve 2 in both the first and second spray gun modules, open the branch regulating valve 3 in both modules to 30% opening, and simultaneously activate the flow PID control program for both modules. Fig. 3 The urea solution injection rate of spray gun 5 is set to SP = N / 2 kg / h, and the urea solution injection rate of spray gun 5 is controlled in real time according to the boiler load changes.

[0027] S2. The pyrolysis furnace transitions from low-load operation mode to high-load operation mode: based on the NO at the denitrification inlet. X The concentration and denitrification efficiency are calculated based on the total amount of urea solution N required for the pyrolysis furnace corresponding to the SCR reactor. The value of N is then assessed. If the total urea solution injection amount N > 80 kg / h, after a 120-second delay, the pyrolysis furnace enters a high-load operation mode, and the third spray gun module is also put into operation. Simultaneously, the urea solution injection rate setting of a single spray gun 5 is adjusted to N / 3 kg / h, ensuring the flow rate of a single spray gun 5 is controlled within the optimal atomization range. The sequential control steps are as follows: Open the branch pneumatic switch valve 2 of the third spray gun module, open the branch regulating valve 3 in the third spray gun module to 30% opening, and activate the flow rate PID control program for the third spray gun module. Fig. 3 The urea solution injection rate settings of the three spray gun modules are all adjusted to SP = N / 3 kg / h, and the urea solution injection rate of spray gun 5 is controlled in real time according to the boiler load changes.

[0028] S3. The pyrolysis furnace transitions from high-load operation mode to low-load operation mode: based on the NO at the denitrification inlet. X The concentration and denitrification efficiency are calculated based on the total urea injection amount N required for the pyrolysis furnace corresponding to the SCR reactor. The value of N is then assessed. If the urea injection amount is 40 ≤ N ≤ 80 kg / h, a 60-second delay is applied, and the pyrolysis furnace enters a low-load operation mode. The third spray gun module is shut down, and the setpoint for the urea solution injection amount per spray gun is adjusted to N / 2 kg / h, ensuring that the flow rate of the single spray gun 5 is controlled within the optimal atomization range. The sequential control steps are as follows: Close the branch pneumatic switch valve 2 in the third spray gun module, and remove the spray gun flow PID control program. Fig. 3 The branch regulating valve 3 in the third spray gun module is opened to 0%, and the urea solution injection rate setting values ​​in the first and second spray gun modules are adjusted to SP = N / 2 kg / h. At the same time, the urea solution injection rate of the spray gun 5 is controlled in real time according to the boiler load change.

[0029] The above merely describes preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A flow-balanced control metering and distribution system for a urea pyrolysis furnace, characterized in that, The system includes a urea pyrolysis furnace (1), and a set of adjustable spray gun modules connected to the urea pyrolysis furnace (1) for controlling the delivery of urea solution into the urea pyrolysis furnace (1). The adjustable spray gun module includes a spray gun (5) with the spray nozzle set inside the urea pyrolysis furnace (1). The first inlet of the spray gun (5) is connected to the urea solution delivery channel through a spray branch pipe (6). The spray branch pipe (6) is equipped with a branch pneumatic switch valve (2), a spray gun branch pneumatic regulating valve (3), and a spray gun branch urea solution flow meter (4).

2. The urea pyrolysis furnace metering and distribution system with flow balance control according to claim 1, characterized in that, The second inlet of the spray gun (5) is connected to a compressed air channel for urea atomization, and its third inlet is connected to a compressed air channel for shutdown purging.

3. The urea pyrolysis furnace metering and distribution system with flow balance control according to claim 2, characterized in that, The branch pneumatic switch valve (2), the spray gun branch pneumatic regulating valve (3), and the spray gun branch urea solution flow meter (4) are arranged sequentially along the spray flow direction of the spray branch pipe (6).

4. The urea pyrolysis furnace metering and distribution system with flow balance control according to claim 3, characterized in that, A demineralized water channel is connected to the pipeline between the branch pneumatic switch valve (2) and the spray gun branch pneumatic regulating valve (3).

5. The urea pyrolysis furnace metering and distribution system with flow balance control according to claim 4, characterized in that, At least one adjustable spray gun module is in operation in the system.

6. The urea pyrolysis furnace metering and distribution system with flow balance control according to claim 1, characterized in that, A spare spray gun assembly is connected to the urea pyrolysis furnace (1), and the spare spray gun assembly has the same structure as the adjustable spray gun module.

7. A flow-balanced control metering and distribution system for a urea pyrolysis furnace according to any one of claims 1-6, characterized in that, The urea pyrolysis furnace (1) is connected to a hot air channel at its inlet and to an ammonia injection grid at its outlet.

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