Furnace smoke extraction lignite drying system of direct-blowing pulverizing system of double-inlet and double-outlet steel ball coal mill

Abstract

The invention relates to a furnace smoke extraction lignite drying system of a direct-blowing pulverizing system of a double-inlet and double-outlet steel ball coal mill. The furnace smoke extraction lignite drying system is simple in structure, low in investment cost, capable of improving the applicability of the pulverizing system to coal types, free of influence to the safety of a boiler, favorable for relieving high-temperature corrosion of a water-cooled wall and reducing NOx emission and the like and capable of increasing the lignite blending ratio to 0.4. The furnace smoke extraction lignite drying system comprises two recirculating pipelines which are connected with an economizer inlet flue of a tail shaft of the boiler, wherein each recirculating pipeline comprises a recirculating fan; an electric side plate gate I and an electric air damper are arranged at the junction of the recirculating fan and the economizer inlet flue; and an electric side plate gate II is arranged at the junction of the recirculating fan and a primary hot air pipeline.

Description

Technical field [0001] The invention relates to a lignite drying system, in particular to a double-inlet and double-outlet steel ball coal mill direct-blowing type pulverizing system exhausting furnace smoke to dry the lignite coal system. Background technique [0002] Since the liberalization of coal market prices in 2006, the price of thermal coal has risen all the way, with bituminous coal prices as high as RMB 800 or 900 per ton. In addition, the policy of "coal-electricity linkage" cannot be implemented in time, and thermal power companies are in a state of serious losses. Lignite is rich in reserves in my country, which is characterized by high moisture content and high volatile content. The price of lignite is low, about 400 yuan per ton. In the past, there were not many power plants that used lignite in our country. In order to reduce the cost of power generation, some bituminous coal-fired units started to burn lignite. Due to the high moisture content of lignite, the d...

AI Technical Summary

Problems solved by technology

[0007] Although this prior art can burn lignite in a large proportion or even burn lignite entirely, it generally has some disadvantages as follows: 1. The coal is pre-dried after the high-temperature furnace smoke extracted from the boiler furnace is mixed with the cold smoke extracted from the boiler flue, The high-temperature furnace smoke contains unburned pulverized coal particles. The extraction of pulverized coal particles not only wastes fuel but also has a great impact on the combustion of the boiler.

2. The coal is pre-dried in the pre-drying device. First, the water is evaporated. However, a part of the volatile matter in the coal will inevitably be precipitated. The volatile matter has high heat and is easy to catch fire, which has a great influence on the ignition and burnout of the coal. Help, part of the volatile matter in this prior art is finally discharged into the atmosphere with the exhaust gas through the desulfurization tower, which is very uneconomical

3. The system is too complicated and there are many devices

For example, it is necessary to set up dust collectors, exhaust air coolers, exhaust air fans, cold exhaust air fans, cold flue gas fans, etc., which makes the initial investment or renovation costs huge

4. As we all know, the more complex the milling system, the more fault points, the lower its stability and reliability, and the heavy workload of repair and maintenance

For example, if the dust collector of the prior art is damaged and needs to be overhauled, the exhaust gas will not be able to remove the pulverized coal particles and will directly enter the desulfurization tower and then be discharged into the atmosphere through the chimney. Although the desulfurization tower can remove part of the pulverized coal particles, it will still cause Environmental pollution and waste of fuel; another example, if the exhaust air cooler is damaged, the moisture in the exhaust air cannot be removed, and the effect of recycling water cannot be achieved

5. One of the components of the drying medium is high-temperature furnace smoke. The temperature of high-temperature furnace smoke is above 1000°C, which is far beyond the temperature limit of 600°C that the existing steel can withstand. This problem needs to be solved by adding insulation materials to the inner wall of the steel pipe, but the inner wall of the steel pipe The insulation material is easy to fall off during actual operation. After the insulation material falls off, the high-temperature flue gas will cause damage to the steel pipe, which will cause the unit to be forced to stop

6. There are three types of fans in this prior art: exhaust fan, cold exhaust fan, and cold smoke fan, and the power consumption of the plant will increase greatly during operation

7. This existing technology is quite different from the current double-inlet and double-outlet steel ball coal mill direct-blowing pulverization system. If the existing unit is modified to burn lignite, the transformation technology is difficult and the transformation cost is high

8. If a new power plant needs to burn all lignite, the fan pulverizer or medium-speed pulverizer direct-blowing pulverization system is recognized and proven to be the most suitable pulverization system for burning lignite. It is currently in operation The units burning lignite almost all use fan pulverizer or medium-speed coal pulverizer direct-blowing pulverization system. There is no advantage in burning lignite if the pulverization system mentioned in this prior art is adopted, and this existing The technology has not been implemented, and its safety, economy, and stability have yet to be tested by time

Images