Nitrogen oxide pre-control device of blast furnace gas boiler

Abstract

The utility model provides a blast furnace gas boiler nitrogen oxide pre-control device which is characterized in that a first temperature measuring device is arranged in a boiler, a second temperature measuring device is arranged at the top of the boiler, and a CEMS (continuous emission monitoring system) flue gas automatic monitoring device is arranged at a boiler gas discharge pipeline. The timer is used for counting down the starting time of the denitration device and transmitting the timing result to the DCS control device, the second temperature measuring device is connected with the input end of the furnace top water fetching signal processor, and the output end of the furnace top water fetching signal processor is connected with the input end of the DCS control device. The input end of the DCS control device is electrically connected with the first temperature measuring device, the second temperature measuring device, the CEMS flue gas automatic monitoring device and the timer respectively, the output end of the DCS control device is connected with the denitration device, the input end of the PID regulator is connected with the output end of the DCS control device, and the output end of the PID regulator is connected with the denitration device.

Description

Technical Field

[0001] The utility model belongs to the technical field of nitrogen oxide control of gas boilers, in particular to a nitrogen oxide pre-control device for a blast furnace gas boiler. Background Art

[0002] At present, most of the boilers that use blast furnace gas to generate electricity in steel enterprises use low-nitrogen combustion technology, which makes the furnace temperature very low, the conditions for the generation of nitrogen oxides are extremely low, and the boiler nitrogen oxide emissions remain within an acceptable range. However, due to the unstable working conditions of the blast furnace, nitrogen oxides are often generated in the blast furnace as the temperature rises. If the denitrification equipment is started and operated all the time, it is not only uneconomical but may also cause corrosion of the flue. According to the CEMS monitoring data, there is often a lag in the start and stop of the denitrification equipment, which causes the emission data to exceed the standard instantly. Chinese invention CN 115475514 B A control system for pre-controlling the denitrification efficiency of a gas boiler by using calorific value and flow rate, a flow meter is installed on the converter and / or coke oven gas pipeline, a calorific value meter is installed on the mixed gas pipeline, and a PID regulator adjusts the opening of the urea inlet regulating valve according to CEMS, converter and / or coke oven gas flow rate, and mixed gas calorific value. If the CEMS detection result cannot meet the emission requirements, the flow rate of blast furnace gas is reduced. After reducing the flow rate of blast furnace gas by 5%, observe whether the CEMS detection result meets the emission requirements after 5 minutes. If it does not meet the emission requirements, continue to reduce the flow rate of blast furnace gas by 5%, until the CEMS detection result meets the emission requirements after 5 minutes. The above device controls the flow rate of blast furnace gas according to the feedback amount of NOX content in the flue gas emission, so that the flue gas emission meets the requirements, but continuously reducing the flow rate of blast furnace gas will affect the final power generation. Summary of the invention

[0003] The technical problem solved by the utility model is that in the prior art, due to the unstable working conditions of the blast furnace, nitrogen oxides are often generated in the blast furnace as the temperature rises. If the denitrification equipment is started and operated all the time, it is not only uneconomical but may also cause corrosion of the flue. The start and stop of the denitrification equipment controlled by the CEMS monitoring data often has a lag, causing the emission data to exceed the standard instantaneously.

[0004] The utility model provides a blast furnace gas boiler nitrogen oxide pre-control device, comprising a first temperature measuring device, a second temperature measuring device, a CEMS flue gas automatic monitoring device, a DCS control device, a furnace top water pumping signal processor, a PID regulator, a timer, and a denitration device, wherein the first temperature measuring device is installed in the boiler furnace, the second temperature measuring device is installed on the boiler furnace top, the CEMS flue gas automatic monitoring device is installed at the boiler gas discharge pipeline, the timer is used for counting down the start time of a denitration device and transmitting the timing result to the DCS control device, the second temperature measuring device is connected to the input end of the furnace top water pumping signal processor, the output end of the furnace top water pumping signal processor is connected to the input end of the DCS control device, the input end of the DCS control device is electrically connected to the first temperature measuring device, the second temperature measuring device, the CEMS flue gas automatic monitoring device, and the timer respectively, the output end of the DCS control device is connected to the denitration device, the input end of the PID regulator is connected to the output end of the DCS control device, and the output end of the PID regulator is connected to the denitration device.

[0005] Furthermore, the first temperature measuring device is used to obtain the temperature inside the boiler furnace and transmit the temperature information to the DCS control device.

[0006] Furthermore, the second temperature measuring device is used to obtain the boiler top temperature and transmit the temperature information to the DCS control device and the top water pumping signal processor. The top water pumping signal processor is used to receive the boiler top temperature information, and after analyzing and calculating, output a signal to the DCS control device indicating whether to pump water to the top of the boiler.

[0007] Furthermore, the CEMS flue gas automatic monitoring device is used to monitor the concentration of nitrogen oxides in the flue gas and transmit the concentration value to the DCS control device.

[0008] Furthermore, the conditions for the DCS control device to pre-control the start-up of the destocking device are: condition 1: the timer timing is not completed and the second temperature measuring device detects that the blast furnace top temperature is greater than 250°C; or condition 2: the timer timing is not completed and the furnace top water pumping signal processor sends a signal that the furnace top water pumping is closed.

[0009] Furthermore, the DCS control device controls the destocking device to shut down under the condition that the first temperature measuring device detects that the temperature inside the blast furnace returns to normal, and the second temperature measuring device detects that the furnace top temperature returns to normal, and the CEMS flue gas automatic monitoring device also monitors that nitrogen oxides are lower than the standard value.

[0010] Furthermore, the PID regulator receives feedback from the concentration of nitrogen oxides monitored by the CEMS flue gas automatic monitoring device and the temperature inside the blast furnace detected by the first temperature measuring device, and is used to dynamically adjust the supply amount of the denitrification reducing agent of the denitrification device.

[0011] Furthermore, the start-up time of the denitrification device is calculated based on the distance from the blast furnace to the boiler pipeline and the gas flow rate to obtain the time when the excess gas enters the furnace, and is calculated based on the denitrification process.

[0012] The utility model has the following beneficial effects: the utility model uses the temperature inside the blast furnace and the temperature on the top of the furnace as the conditions for predicting the increase of nitrogen oxides in coal gas, starts the denitration device in advance, and adds the temperature inside the blast furnace and the temperature on the top of the furnace in the PID regulation to achieve accurate control of the denitration reducing agent. It avoids the hysteresis of adjusting after the flue gas online monitoring returns the data, avoids the problem of excessive nitrogen oxide emissions from the boiler caused by the drastic fluctuation of the nitrogen oxide content in the coal gas, and greatly reduces the operation time of the denitration equipment, saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 , Schematic diagram of the connection of the nitrogen oxide pre-control device for blast furnace gas boiler of the utility model. DETAILED DESCRIPTION

[0014] In order to clearly illustrate the technical features of this solution, the solution is described below through specific implementation methods and in combination with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the utility model.

[0015] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0016] like Figure 1 As shown, a blast furnace gas boiler nitrogen oxide pre-control device includes a first temperature measuring device, a second temperature measuring device, a CEMS flue gas automatic monitoring device, a DCS control device, a furnace top water injection signal processor, a PID regulator, a timer, and a destocking device.

[0017] The first temperature measuring device is installed in the boiler furnace to obtain the temperature in the boiler furnace and transmit the temperature information to the DCS control device. The second temperature measuring device is installed on the boiler furnace top to obtain the boiler furnace top temperature and transmit the temperature information to the DCS control device and the furnace top water injection signal processor. The CEMS flue gas automatic monitoring device is installed at the boiler gas emission pipeline to monitor the concentration of nitrogen oxides in the flue gas and transmit its concentration value to the DCS control device. The timer is used to count down the start time of the denitrification device and transmit the timing result to the DCS control device.

[0018] The second temperature measuring device is connected to the input end of the furnace top water pumping signal processor, and the output end of the furnace top water pumping signal processor is connected to the input end of the DCS control device. The furnace top water pumping signal processor is used to receive the boiler furnace top temperature information, and after analysis and calculation, output a signal of whether the furnace top is watered to the DCS control device. The DCS control device input end is electrically connected to the first temperature measuring device, the second temperature measuring device, the CEMS flue gas automatic monitoring device, and the timer, respectively, the DCS control device output end is connected to the de-pinning device, the PID regulator input end is connected to the DCS control device output end, and the PID regulator output end is connected to the de-pinning device.

[0019] The specific pre-control method includes the following steps:

[0020] a. Calculate the time when the excessive gas enters the furnace based on the distance from the blast furnace to the boiler and the gas flow rate, and calculate the start time of the denitrification device based on the denitrification process, and enter it into the timer, which starts timing.

[0021] b. The blast furnace process requires that the furnace top temperature is generally controlled between 220℃-240℃. When condition 1 is met, the timer timing is not completed and the second temperature measuring device detects that the blast furnace top temperature is greater than 250℃, or condition 2 is met, the timer timing is not completed and the furnace top water pumping signal processor sends a signal that the furnace top water pumping is closed, the DCS control device pre-controls the denitrification device to start.

[0022] c. After the denitrification device is started, the DCS control device feeds back the concentration of nitrogen oxides monitored by the CEMS flue gas automatic monitoring device and the temperature inside the blast furnace detected by the first temperature measuring device to the PID regulator. The PID regulator dynamically adjusts the supply amount of the denitrification reducing agent of the denitrification device based on the feedback from the two.

[0023] d. When the first temperature measuring device detects that the temperature inside the blast furnace has returned to normal, and the second temperature measuring device detects that the temperature at the furnace top has returned to normal, and the CEMS flue gas automatic monitoring device also monitors that the nitrogen oxides are lower than the standard value, the DCS control device controls the denitrification device to shut down.

[0024] The utility model starts the denitration device in advance by taking the temperature inside the blast furnace and the temperature on the top of the furnace as the conditions for predicting the increase of nitrogen oxides in the coal gas, and adds the temperature inside the blast furnace and the temperature on the top of the furnace in the PID regulation to achieve accurate control of the denitration reducing agent, thereby avoiding the lag in adjustment after the data is sent back by the online monitoring of the flue gas, avoiding the problem of excessive nitrogen oxide emissions from the boiler caused by the drastic fluctuation of the nitrogen oxide content in the coal gas, and greatly reducing the operating time of the denitration equipment and saving costs.

[0025] Other parts of the present invention not described in detail belong to the prior art and will not be described in detail here.

[0026] It is understood that the present invention is described by some embodiments, and those skilled in the art are aware that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A blast furnace gas boiler nitrogen oxide pre-control device, characterized in that: It includes the first temperature measuring device, the second temperature measuring device, the CEMS flue gas automatic monitoring device, the DCS control device, the furnace top water supply signal processor, the PID regulator, the timer, and the destocking device. The first temperature measuring device is installed in the boiler furnace, the second temperature measuring device is installed on the boiler furnace top, the CEMS flue gas automatic monitoring device is installed at the boiler gas exhaust pipeline, and the timer is used to count down the start time of the denitrification device and transmit the timing result to the DCS control device. The second temperature measuring device is connected to the input end of the furnace top water supply signal processor, and the output end of the furnace top water supply signal processor is connected to the input end of the DCS control device. The input end of the DCS control device is electrically connected to the first temperature measuring device, the second temperature measuring device, the CEMS flue gas automatic monitoring device, and the timer respectively; the output end of the DCS control device is connected to the out-of-stock device; the input end of the PID regulator is connected to the output end of the DCS control device; and the output end of the PID regulator is connected to the out-of-stock device.

2. The blast furnace gas boiler nitrogen oxide pre-control device according to claim 1, characterized in that: The first temperature measuring device is used to obtain the temperature inside the boiler furnace and transmit the temperature information to the DCS control device.

3. The blast furnace gas boiler nitrogen oxide pre-control device according to claim 1, characterized in that: The second temperature measuring device is used to obtain the boiler top temperature and transmit the temperature information to the DCS control device and the top water supply signal processor. The top water supply signal processor is used to receive the boiler top temperature information, and after analyzing and calculating, output a signal to the DCS control device indicating whether to supply water to the top of the boiler.

4. The blast furnace gas boiler nitrogen oxide pre-control device according to claim 1, characterized in that: The CEMS flue gas automatic monitoring device is used to monitor the concentration of nitrogen oxides in the flue gas and transmit the concentration value to the DCS control device.

5. The nitrogen oxide pre-control device for blast furnace gas boiler according to claim 1, characterized in that: The conditions for the DCS control device to pre-control the start-up of the destocking device are: condition 1: the timer timing is not completed and the second temperature measuring device detects that the blast furnace top temperature is greater than 250°C; or condition 2: the timer timing is not completed and the furnace top water pumping signal processor sends a signal that the furnace top water pumping is closed.

6. The nitrogen oxide pre-control device for blast furnace gas boiler according to claim 1, characterized in that: The DCS control device controls the destocking device to shut down under the following conditions: the first temperature measuring device detects that the temperature inside the blast furnace has returned to normal, the second temperature measuring device detects that the furnace top temperature has returned to normal, and the CEMS flue gas automatic monitoring device also monitors that nitrogen oxides are lower than the standard value.

7. The nitrogen oxide pre-control device for blast furnace gas boiler according to claim 1, characterized in that: The PID regulator receives feedback from the concentration of nitrogen oxides monitored by the CEMS flue gas automatic monitoring device and the temperature inside the blast furnace detected by the first temperature measuring device, and is used to dynamically adjust the supply amount of the denitration reducing agent of the denitration device.

8. The nitrogen oxide pre-control device for blast furnace gas boiler according to claim 1, characterized in that: The start-up time of the denitrification device is calculated based on the distance from the blast furnace to the boiler pipeline and the gas flow rate to obtain the time when the excessive gas enters the furnace, and is also calculated based on the denitrification process.

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