Cement SNCR intelligent operation and maintenance method and system

Abstract

The invention discloses a cement SNCR intelligent operation and maintenance method and system, and belongs to the technical field of cement industrial flue gas denitration. The system comprises a data collection module, a data calculation and analysis module, a performance evaluation module and an automatic control coupling module; the data collection module is used for obtaining the operation data of a cement DCS, the detection data of a preheater outlet flue gas analyzer, the detection data of a chimney flue gas analyzer, and manual initial setting parameters; the data calculation and analysis module is used for receiving the data of the collection module and carrying out data calculation and analysis; the performance evaluation module is used for evaluating the working state of the preheater outlet flue gas analyzer, evaluating and diagnosing the running state of a cement kiln system and judging the current running state of the cement kiln by using the data obtained by the data calculation and analysis module; the automatic control coupling module performs data interaction with the performance evaluation module and predicts the current optimal ammonia water consumption and the current optimal compressed air flow so as to automatically adjust the flow of ammonia water and the flow of compressed air; and the adjusted parameters are re-imported into the data collection module, so that a cycle is established.

Description

Technical field: [0001] The invention belongs to the technical field of flue gas denitrification in the cement industry, and in particular relates to a cement SNCR intelligent operation and maintenance method and system. Background technique: [0002] Nitrogen oxides are pollutants that are harmful to the environment and can easily cause acid rain and other hazards. In order to strengthen environmental protection, my country has formulated GB4915-2013 "Emission Standard of Air Pollutants for Cement Industry" to control nitrogen oxide emissions. At present, the cement industry mostly adopts selective non-catalytic reduction technology (SelecTive non-caTalyTic reacTion, or SNCR) to reduce nitrogen oxide emissions. Because of the advantages of simple SNCR technological transformation and small investment, it has been widely used, and now there are many improvements. For example, CN111773909A focuses on improving the use effect of spray guns. First, the spray guns are grouped a...

AI Technical Summary

Problems solved by technology

However, there are some problems in the patent CN105938375A: when the system automatically calculates the initial nitrogen oxide concentration in reverse, the solution assumes that the initial nitrogen oxide concentration does not change within this time range, so as to track, but the initial nitrogen oxide concentration often fluctuates very frequently , especially under the current ultra-low emission background, the initial nitrogen oxide emission concentration is very unstable, and the automatic adjustment process of this scheme is difficult to achieve continuous and stable operation

However, there are some practical problems in this scheme: First, the working conditions at the inlet of the ammonia injection area of ​​the calciner and the outlet of the calciner are harsh, the flue gas temperature is 850-950°C, and the dust concentration is as high as 500-1500g / Nm3. The accuracy and precision of the nitrogen oxide concentration detection sensors used in a small amount are low and the failure rate is extremely high, and the data utilization value is low

At the same time, the existing flue gas flow monitoring sensors and ammonia concentration detection sensors cannot meet the installation conditions here, and the ammonia escape correction parameters cannot be obtained.

Therefore, the method of patent CN104793651A cannot be realized due to practical factors

Second, the production of cement clinker is not a stable production process. Changes in the composition and dosage of various raw materials and fuels of cement, and changes in the performance of cement process equipment will cause changes in the cement process, thereby affecting the formation of nitrogen oxides. , fine-tuning only by temperature correction coefficient and ammonia escape correction coefficient, which deviates greatly from the actual situation

However, this scheme also has obvious shortcomings: first, the influence of cement kiln on SNCR is abstracted into two parameters of coal feeding amount and sludge addition amount, ignoring the influence of other cement process parameters on SNCR, and the accuracy is not high; second , the influence of coal feed amount and sludge addition amount on SNCR is subjectively characterized as a linear effect, which is far from the actual SNCR, so the control effect is not ideal

[0011] First, the chimney flue gas analyzer of the traditional SNCR is far away from the SNCR reaction zone, and the nitrogen oxide emission concentration is prone to exceed the standard. Using the feedback data of the chimney flue gas analyzer as the control parameter of the SNCR has serious hysteresis

Even if some researchers increase the flue gas flow rate, ammonia escape parameters, and adopt a variety of control strategies, they still cannot solve this problem.

[0012] Second, the emission concentration of nitrogen oxides in the cement industry fluctuates greatly and the frequency of change is fast. Even if some scholars add a flue gas analyzer to C1 to shorten the detection lag, due to the working environment of the C1 flue gas analyzer and the existence of chimneys There is a big difference, the data synchronization is poor, and due to the cement process, the lag time between the C1 flue gas analyzer and the chimney flue gas analyzer is not a fixed value. Simply use the C1 flue gas analyzer instead of the chimney flue gas analyzer to control the accuracy. still poor

[0013] Third, the logical relationship between the change of various process parameters of the cement kiln and the concentration of nitrogen oxide emissions and SNCR control is unreasonable, and the numerical simulation results cannot guide production at this stage.

The current control logic cannot effectively predict the concentration change of nitrogen oxides through the change of process parameters, so as to control the SNCR system

[0014] Fourth, the current denitrification of cement mainly considers fuel nitrogen oxides and thermal nitrogen oxides, and basically does not involve the raw material nitrogen oxides carried in cement raw meal

Therefore, the logical relationship of SNCR control rarely takes into account the impact of raw meal on NOx emissions and SNCR

[0015] At present, the SNCR control system mainly controls the flow of ammonia water, but does not pay attention to the adjustment of compressed air flow, and generally only plays the role of metering and monitoring

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