A kind of urea mixing dilution system and its control method for SNCR denitrification
A control method and urea technology, applied in the directions of mixing methods, mixers, separation methods, etc., can solve the problems of inaccurate measurement of feedback signal flow value, inability to guarantee, affecting the denitration effect, etc., to overcome the inaccuracy of electromagnetic flow and ensure accurate Sexual and economical good effect
Inactive Publication Date: 2020-11-20
HARBIN UNIV OF SCI & TECH
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Problems solved by technology
[0002] SNCR is a selective non-catalytic reduction technology. The SNCR denitrification process does not use a catalyst, and the amino reducing agent is directly sprayed into an appropriate position in the boiler furnace to reduce NOx to N2. The reducing agent generally uses ammonia or urea. In the SNCR denitrification process , now the high-concentration urea solution is configured in the dissolution tank, and then the high-concentration urea solution is transported to the storage tank for storage. The higher concentration is for the convenience of transportation and storage. The urea solution is diluted and then sent to the boiler furnace for spraying. The accuracy of the diluted concentration of the urea solution will directly affect the denitrification effect of the follow-up flue gas in the furnace. waste, increasing unnecessary costs
[0003] In the current denitrification process, the mixing and dilution part of the drug solution is generally adopted as a mixing method, and the concentration after dilution is set. The controller controls two frequency converters to control the frequency of the urea delivery pump and the dilution water pump to control the high-concentration urea solution. and the flow rate of softened water, or control the opening of the regulating valve to control the flow rate of the liquid medicine and softened water. According to the measured flow information, timely adjust the output frequency of the inverter or adjust the valve to control the flow. This method has great disadvantages. It is difficult to ensure the accuracy of the measurement by using an electromagnetic flowmeter to measure the flow of liquid medicine and softened water. Electromagnetic flow The meter has strict requirements on the head parameters of the pump, the length of the pipeline of the equipment, and the shape of the turning point, especially the requirements for straight pipelines are very high. It is necessary to specially design pipelines for electromagnetic flowmeters. If the pipelines in the factory area are relatively old, it is necessary The pipeline has undergone a thorough upgrade, and after the flowmeter is installed and debugged, once the pipeline line in the factory is slightly changed, the flow measurement system needs to re-perform the parameter setting experiment to change the previously set parameters. In addition, the installation of the flowmeter The position and the flow rate of the liquid in the pipeline have an impact on the measurement. If the pipeline is not filled with liquid or the liquid in the pipeline contains air bubbles, it will seriously affect the accuracy of the flowmeter measurement. The flow value measurement of the feedback signal is not accurate. Simply use the frequency converter And the regulating valve cannot guarantee that the concentration of the diluted chemical solution in the mixing dilution tank remains at the set value at any time, which will cause incomplete denitrification in the boiler furnace or waste the chemical solution. The entire method of dilution of the chemical solution must ensure accurate measurement. The requirements for other equipment are very high, which increases the construction cost of the entire urea solution dilution system, and the equipment is complex and has a high failure rate, which affects the overall denitrification system operating efficiency
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[0032] Specific implementation mode two, combined with attached figure 1 to attach image 3 , to describe the present invention in detail,
[0033] A kind of urea mixing dilution system and its control method for SNCR denitrification of the present invention,
[0034] Step 1: Measure the flow rate of urea solution v 1 and the dilution water flow rate v 2 ;
[0035] The PLC controller 1503 controls the opening of the urea delivery pump 4 and the urea medicinal solution regulating valve 702, and the high-concentration urea in the urea storage tank 1 is pumped into the mixing and dilution tank 3 through the urea delivery pump 4 until it is full, the PLC controller 1503 The internal timer records the length of time from start to end as T 1 , the volume of the mixing and diluting tank 3 is denoted as V, then the flow rate of urea liquid medicine
[0036] Afterwards, the system drains the urea in the mixing and dilution tank 3, and then pumps the demineralized water in the d...
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A urea mixing and dilution system for SNCR denitrification and its control method, belonging to the field of urea liquid dilution technology, the technical points are: including urea storage tank, desalted water tank, mixing and dilution tank, urea delivery pump, dilution water pump, magnetic Flap level gauge, temperature sensor, pressure transmitter, urea concentration detector, heat tracing device, power distribution room and control cabinet, the urea storage tank is connected to the urea delivery pump through pipelines, and the desalted water tank is connected to the dilution water pump through pipelines , the dilution water pump is connected to the mixing dilution tank through the pipeline through the dilution water regulating valve, and a pressure transmitter is installed in the middle of the connection between the dilution water regulating valve and the mixing dilution tank pipeline, and a magnetic flap liquid level gauge is fixedly installed on the inner wall of the mixing dilution tank ,A heat tracing device is installed spirally inside the urea storage tank, the outlet of the heat tracing device is connected to the hot water return network through a manual ball valve, and a magnetic flap liquid level gauge is fixedly installed on one side of the inner wall of the desalinated water tank.
Description
technical field [0001] The invention relates to the technical field of urea liquid dilution in the SNCR denitrification process, in particular to a urea mixing and dilution system for SNCR denitrification and a control method thereof. Background technique [0002] SNCR is a selective non-catalytic reduction technology. The SNCR denitrification process does not use a catalyst, and the amino reducing agent is directly sprayed into an appropriate position in the boiler furnace to reduce NOx to N2. The reducing agent generally uses ammonia or urea. In the SNCR denitrification process , now the high-concentration urea solution is configured in the dissolution tank, and then the high-concentration urea solution is transported to the storage tank for storage. The higher concentration is for the convenience of transportation and storage. The urea solution is diluted and then sent to the boiler furnace for spraying. The accuracy of the diluted concentration of the urea solution will ...
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IPC IPC(8): B01F3/08B01F15/00B01F15/02B01D53/56B01D53/79
CPCB01D53/56B01D53/79B01D2251/2067B01D2258/0283B01F23/49B01F35/2206B01F35/712B01F35/7176B01F35/718051B01F2101/48
Inventor周美兰杨明亮陈麒龙刘洋刘俊鹏王嘉明
OwnerHARBIN UNIV OF SCI & TECH