Measuring method of combustion rate signal of large-scale boiler

Abstract

The invention discloses a real-time calculating and measuring method of a combustion rate signal of a large-scale boiler, belonging to the technical field of thermal engineering parameter measurement and thermal engineering automation and relating to the utilization of total air volume signals and exhaust smoke oxygen volume signals of the boiler. The method comprises the following steps of: firstly, correcting exhaust smoke oxygen volume signals and air volume signals of a large-scale boiler; calculating an air heat ratio according to provided coal variety and coal quantity; and calculating the combustion rate of the boiler by adopting the following formula to calculate and measure a combustion rate signal of the large-scale boiler in real time. The method calculates the combustion rate signal of the boiler by utilizing original total air volume and exhaust smoke oxygen volume signals of the boiler without adding new measuring points, has extremely simple configuration logic, can be realized in any DCS (Distributed Control System), PLC (Programmable logic controller) or SCADA (Supervisor Control And Data Acquisition). The method has the advantages of low cost, high precision, good dynamic characteristic, high reliability, extremely easy debugging and simple maintenance and can be used in the detection of the combustion states of boilers and the optimization design and the modification of main control systems of a boiler, such as steam temperature, water supply, combustion, and the like.

Description

technical field The invention belongs to the technical field of thermal parameter measurement and thermal automation. In particular, it relates to a real-time calculation and measurement method for a large boiler combustion rate signal using the boiler total air volume and exhaust smoke oxygen signal. Background technique The boiler combustion rate is defined as the heat released instantaneously by the fuel burning in the boiler furnace, and the unit is MW, also known as the boiler heat signal. At present, there is no direct measurement method and instrument. This signal can play an important role in the monitoring and control of the main operating parameters in the boiler operating state. Because it cannot be directly measured, in the current large-scale boiler measurement and control system, only other signals that have a certain correlation with the boiler combustion rate signal can be used instead, but there are many problems in application. Large-scale coal-fired boi...

AI Technical Summary

Problems solved by technology

The main problems are: (1) The amount of pulverized coal fed into the boiler furnace is not only affected by the capacity wind, but also related to factors such as coal quality and coal level in the coal mill

(2) The capacity wind and the amount of pulverized coal it carries are only approximately linear, and there are nonlinear errors under different coal mill loads

The main problems are: (1) There is a large difference in the dynamic time between the coal supply signal and the boiler combustion rate signal

There is a large inertia and delay in this process

(2) When the pulverizing system is abnormal, the coal feed signal cannot accurately represent the boiler combustion rate signal

(4) The application effect of coal calorific value correction is not good

The main problems are: (1) There is a large error in the amount of powder fed by the speed of the powder feeder, especially when powder blocking or self-flow of coal powder occurs, the signal is completely distorted

(2) There is a large nonlinearity between the speed of the powder feeder and the amount of powder fed under different loads

(3) The application effect of coal calorific value correction is not good

The main problems of DEB heat signal replacing the boiler combustion rate signal are: (1) With the increase of boiler steam parameters, especially the once-through boiler with supercritical parameters, the energy transfer process in the boiler presents a greater distribution characteristic, Only relying on the change of steam drum pressure to reflect the error of boiler heat storage is very large, and at the same time, the steam drum pressure is also more affected by other signals, the accuracy of DEB heat signal becomes worse, and the noise becomes larger

(2) The DEB heat signal is obtained by calculating the parameters of the steam-water system of the boiler. The fuel burns in the boiler to release heat, which needs to go through the heat absorption and heat storage of the boiler heating surface before reaching the steam-water system. Therefore, the dynamic characteristics of the DEB heat signal are poor, and it is difficult to Reflect the instantaneous characteristics of the combustion process

In addition, there are methods such as installing a CCD camera in the boiler furnace to measure the boiler combustion rate through image analysis, and installing a sonic temperature measurement device in the boiler furnace to calculate the boiler combustion rate. There are problems such as large equipment investment, difficult installation and maintenance, and poor measurement accuracy.

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