Ventilation control system and method applicable to dry type slag extractor

Abstract

The invention relates to a ventilation control system and method applicable to a dry type slag extractor, which have simple structure and can effectively control the quantity of cold air entering a boiler. The ventilation control system comprises a slag extractor which is divided into a horizontal section and an inclined section, wherein ventilating devices are respectively arranged at the horizontal section and the inclined section; a tail end of the inclined section is a slag falling port; the ventilating devices are connected with a ventilation control unit; meanwhile, a first stage of temperature measuring device and a second stage of temperature measuring device are respectively arranged on an intersected part of the horizontal section and the inclined section and an upper part of the inclined section; and two stages of temperature measuring devices are both connected with the ventilation control unit.

Description

[0001] technical field [0002] The invention relates to a ventilation control system and method suitable for a dry slag discharger, which can intelligently adjust the amount of cold air entering the boiler, can control the ventilation amount according to the slag temperature and slag amount, and can burn coal at low load In the case of a small amount, reduce the amount of cold air entering the boiler and improve the combustion efficiency of the boiler. Background technique [0003] Since the dry slag discharge system has the advantages of water saving, low power consumption of auxiliary equipment, and wide application of dry slag, more and more power plants adopt dry slag discharge system for renovation or initial establishment. The basic principle of dry slag discharge system is The convective movement between the ambient air and the hot slag is used for heat exchange, so that the hot slag is discharged after being cooled, and the cold air is heated, and then enters the fu...

AI Technical Summary

Problems solved by technology

At present, the most installed in our country is the MAC system imported from Italy MAGALDI company. You can refer to the document "Application of dry slag removal system on domestic 200MW units". The amount of cold air entering the furnace in the MAC system is uncontrollable, and its design The amount of cold air is designed according to the maximum output of the boiler. Since the negative pressure of the boiler is constant during normal operation, the amount of cold air entering the boiler is equal to the amount of the maximum output of the boiler even when the boiler is under low load. The result is that the amount of cold air entering the furnace is too large when the boiler is running at low load, which not only affects the combustion stability of the boiler, but also increases the air leakage at the bottom of the boiler, reduces the air volume passing through the air preheater, and increases the exhaust gas temperature and reduces the boiler economy. sex

[0004] A Japanese dry slag discharge patent JP-A-63-6319 and a Chinese patent 02135342.5 also cannot control the amount of cold air entering the furnace, and have the same problem as the MAC system that affects the combustion stability of the boiler

[0005] Among the domestic dry slag removal machine patents, patent 00209485.1 and patent 200920073690.8 adopt the same principle of controlling the amount of cold air, that is, a baffle is added to the vent, and the baffle is sucked open by the negative pressure of the furnace to allow the natural cold air to enter the cooling heat. Slag, we know that the negative pressure of the furnace is basically stable during normal operation of the boiler, that is, the negative pressure of the furnace does not change with the load of the boiler, so that when the boiler is under low load, the amount of natural cooling air entering the furnace does not decrease, that is to say When the load is reduced and the amount of slag is reduced and the maximum load is reached, the amount of cold air entering the furnace is the same. It can be said that this structure for controlling the amount of ventilation cannot effectively change the amount of ventilation and improve the boiler under non-rated load conditions. Boiler economy; patent 200920312413.8 proposes a remote-operated damper device, and does not propose how to install the damper, and what parameters or variables are used for automatic adjustment. The claim is only a device that can be installed on a dry slag discharger Electric damper that can be operated remotely; in patent 200610011273.1, the pressure difference of two vacuum pressure gauges is used to control the amount of cold air entering the furnace through a pneumatic baffle

There are major difficulties in the realization of this method mainly manifested in (1). Due to the small fluctuation range of boiler negative pressure (between -100 and 100Pa during normal operation), the sensitivity and precision of the vacuum pressure gauge are required to be high, while the vacuum pressure gauge is required to have high sensitivity and precision. The environment where the meter is located is high temperature and dusty, the pressure transmission tube is easily blocked, and the meter is easily damaged

Moreover, in extreme situations such as boiler fire extinguishing, the negative pressure of the furnace can reach -3000Pa, so the vacuum pressure gauge may be damaged beyond the range

(2) Due to the relatively stable negative pressure of the furnace, the pressure difference between the two vacuum pressure gauges is relatively small. This result produces two situations. One is that if the sensitivity of the controller is set higher, it will cause two The load of the cylinder of the pneumatic baffle and the induced fan is constantly adjusted and changed, causing damage to the equipment. Another situation is that if the sensitivity is designed to be low, the baffle will not move and will not be able to adjust the air volume.

[0006] According to the above analysis, it can be found that there is a lack of a reliable and effective method for adjusting the amount of cold air entering the furnace.

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