Treatment method of circulating fluidized bed boiler multipoint bed temperature signal

Abstract

The invention discloses a treatment method of a circulating fluidized bed boiler multipoint bed temperature signal. The method comprises the steps that firstly, according to the distribution law of bed temperature measuring point measuring values and all bed temperature signal average value deviation, the bed temperature measuring points are divided into the high temperature area, the normal temperature area and the low temperate area, the bed temperature measuring points in each temperature area are grouped, bed temperature signals of the bed temperature measuring points in each set are subject to three-selection treatment, the represented bed temperature signal of the group is obtained, the represented bed temperature signals of the classification same temperature areas are subject to average value calculation, the average bed temperature signal of each temperature area is obtained, the average bed temperature signals of the three temperature areas are subject to weighing average treatment finally, and an optimized calculation bed temperature is obtained. The traditional average value method and the median method are organically combined, the advantages of the average value method and the median method are obtained, the characteristics that under the high load, the local high bed temperature signal changes are subject to priority reflecting, and under the low load, the locallow bed temperature signal changes are subject to priority reflecting are achieved, and the control quality of a circulating fluidized bed boiler can be effectively improved.

Description

technical field [0001] The invention relates to a method for processing multi-point bed temperature signals of a circulating fluidized bed boiler to obtain bed temperature signals required for optimal calculation of a bed temperature control system, belonging to the field of control technology. Background technique [0002] Circulating fluidized bed boilers have developed rapidly in recent years because of their advantages such as strong adaptability to coal types, good low-load stable combustion performance, small amount of nitrogen oxides generated by low-temperature fuel combustion, and low environmental protection costs for desulfurization in the furnace. Hearth temperature is an important monitoring signal of circulating fluidized bed boiler. Excessive bed temperature will easily lead to failures such as melting and coking of the bed material, overheating of the metal on the heating surface in the bed, etc., and will also reduce the desulfurization efficiency in the fur...

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Problems solved by technology

[0006] The bed temperature signal obtained by using the averaging method can reflect the bed temperature reference and the overall change trend, and can also eliminate the influence of random disturbances, but there are the following disadvantages: (1) Due to the limitations of manufacturing, installation process and operating conditions, the material in the bed The distribution and combustion intensity are not uniform, there are local high temperature areas and low temperature areas, and the temperature deviation of the high temperature area and low temperature area from the average bed temperature often exceeds ±50°C, and the average bed temperature is normal during high load operation, but the bed temperature measurement in the local high temperature area often occurs. Over-temperature alarms at low-load points, normal average bed temperature during low-load operation but under-temperature alarms at bed temperature measurement points in local low-temperature areas; If the measured temperature value at a certain point is obviously abnormal but the signal quality detection is normal, such abnormal signal points will also be involved in the calculation, causing the average bed temperature to deviate

[0007] The bed temperature signal obtained by using the median method can overcome the problems caused by the obvious abnormality of several single-point bed temperature measurements, but it has the following disadvantages: (1) Due to the uneven distribution and combustion intensity of the material in the bed, the It often happens that the direction and rate of change of a single point bed temperature are inconsistent with the average bed temperature. If this signal is selected as the median bed temperature at a certain moment, it will cause the control system to apply control output in the wrong direction. Thus, the control quality is reduced; (2) Finding the median cannot eliminate the random interference components contained in the single-point bed temperature signal. Since the bed temperature is a controlled object with large inertia and large delay, the control system must adopt a strong differential adjustment to ensure the control quality , and the differential adjustment effect will amplify the random disturbance component and cause the control output to fluctuate violently; (3) To find the median value, it is necessary to sort multiple (more than three) input signals according to their size. The sorting programming is relatively easy to implement, but the configuration implementation is very difficult. Difficult, there is no multi-input sorting function module or multi-input median value function module in the DCS (distributed control system) widely used in large-scale units, and the configuration logic for calculating the median bed temperature in DCS is very complicated

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