Direct fired pulverizing system of smoke pre-drying lignite fan mill

Abstract

The invention discloses a direct fired pulverizing system of a smoke pre-drying lignite fan mill. A coal dropping port of a coal delivery pipe is connected with a pre-drying device; a coal inlet and a high-temperature smoke dryer inlet are arranged on the upper part of the pre-drying device; an exhaust port is arranged on the side of the bottom and connected with a dust remover; an exhaust outlet of the dust remover is connected with an exhaust fan; a powder outlet of the dust remover is connected with a powder dropping port of the coal delivery pipe; the high-temperature smoke dryer inlet of the pre-drying device is connected with a smoke mixing chamber that is provided with two smoke inlets; and the first smoke inlet is connected with a hot smoke pumping port of a boiler furnace, while the second smoke inlet is connected with a cool smoke pumping port of the boiler furnace. The direct fired pulverizing system has a series of advantages such as good drying effect, safety in operation, and capability in improving combustion performance of pulverized coal and lowering coal consumption for power generation. The direct fired pulverizing system can be used for transformation of steel ball mill pulverizing system of the in-service lignite generator units, or lately built combustible high-moisture lignite generator units and has great promotion and application prospect.

Description

technical field [0001] The invention belongs to the technical field of coal-fired power generation, and relates to lignite power generation technology. Specifically, it relates to a pulverizing system and a combustion system of a coal-fired power station boiler. Background technique [0002] Lignite is the mineral coal with the lowest degree of coalification. It is the initial product of peat deposition that is dehydrated and compacted into organic biorock. It is named for its brown or dark brown appearance. Lignite accounts for about 18% of my country's thermal coal reserves, mainly distributed in Inner Mongolia, Northeast China and Yunnan. Lignite has a high volatile content (V daf >37%), high moisture (total moisture is about 30%, external moisture mostly exceeds 19%), low calorific value (about 12.56MJ / kg), low ash melting point (about 1150°C), low abrasiveness (HGI is 50-70) and easy spontaneous combustion and other characteristics. The characteristics of "two hi...

AI Technical Summary

Problems solved by technology

One is the high oxygen content in the drying medium, which is easy to cause accidents such as fire and deflagration in the pulverizing system, which affects the safe operation of the pulverizing system; the other is that a large amount of raw coal moisture dried in the pulverizing system enters the boiler furnace together with the pulverized coal , which not only deteriorates the combustion performance of pulverized coal, but also reduces the power generation efficiency of the unit

[0008] To sum up, it can be seen that the current lignite drying and upgrading processes have not been applied on a large scale due to problems such as huge investment and unstable operation, and there are still many problems in the storage, packaging, and transportation of lignite after upgrading.

At present, the two-medium and three-medium dry lignite pulverization systems widely used in power plant boilers focus on the drying and pulverization of high-moisture lignite, which cannot effectively solve the safety problem of the lignite pulverization system, and will dry a large amount of raw coal. Moisture is sent into the boiler furnace, failing to realize the idea of ​​burning upgraded coal

Images