Wind powder mixing temperature and flow speed secondary adjusting system

Abstract

The invention discloses a wind powder mixing temperature and flow speed secondary adjusting system. A wind outlet of a primary fan is divided into two paths. One of the two paths communicates with a hot wind inlet of an adjusting system and an inlet of a first valve through an air preheating device. An outlet of the first valve communicates with a wind inlet of a coal mill. The other path of the two paths communicates with a cold wind inlet of the adjusting system and an inlet of a second valve. An outlet of the second valve communicates with the wind inlet of a coal mill. An outlet of a coal feeding device communicates with a coal inlet of the coal mill. An outlet of the coal mill, an outlet of a wind powder air-solid two-phase temperature and flow speed adjusting system and inlets of burners on a furnace communicate with one another. According to the wind powder mixing temperature and flow speed secondary adjusting system, secondary adjusting of wind coal mixing temperature and flow speed can be achieved, the problems of coal powder pipeline backfiring, burning loss of spraying nozzle, burner surrounding coking and overtemperature of the wall temperature of the water cool wall and the metal wall which are caused by once low wind speed are solved, safe and stable running of the system is ensured, and meanwhile, the coal powder burned-out performance, the furnace underload burning stability and the running flexibility of machine units are improved.

Description

technical field [0001] The invention belongs to the field of thermal power generation equipment and relates to a secondary adjustment system for air powder mixing temperature and flow velocity. Background technique [0002] The pulverizing system is an important auxiliary equipment for the pulverized coal boiler of the power station, and whether its safe and stable operation is very important to the power station boiler. The deflagration of coal accumulation in the pipeline is an important factor that threatens the safety of the pulverization system (coal mill) and its communication equipment, as well as the pulverized coal pipeline. Wind powder mixing temperature to ensure system safety. The "Guidelines for Selection of Coal Mills and Pulverizing Systems in Power Stations" (DL / T 466-2004) gives the maximum temperature allowed at the outlet when different types of coal mills grind different types of coal. The temperature of the mixture is controlled below 63°C, and when bi...

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Problems solved by technology

[0005] First, an increase in the intake of cold air will lead to an increase in the exhaust gas temperature. According to the field test results, after the air-powder mixing temperature at the outlet of the coal mill is increased from 76°C to 90°C, the exhaust gas temperature can drop by 9.8°C, which can reduce the power supply Coal consumption is about 1.5g / (kW·h)

[0006] Second, the low air-powder mixing temperature in the pulverized coal pipeline will reduce the combustion reaction rate, increase the ignition distance, and reduce the burnout of pulverized coal. In high altitude areas, the above problems will become more prominent

[0007] Third, during the 13th Five-Year Plan period, my country plans to implement the flexible transformation of 220 million kilowatts of coal-fired units. How to improve the boiler's low-load stable combustion capability has become its main research goal, and the low coal powder mixing temperature is obviously not conducive to stable combustion.

[0008] In addition, when the coal combustion deviates from the designed coal type, the current combustion adjustment methods have many restrictions and limited impact on problems such as burner loss caused by low primary wind speed, overheating of the water wall in the burner area, and coking at the nozzle. Design a system that can adjust the temperature and flow rate of air-coal mixing in a specific pulverized coal pipeline to solve the above problems

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