Method and device for ultralow-load stable combustion of pulverized coal fired boiler in power plant

Abstract

The invention discloses a method and a device for ultralow-load stable combustion of a pulverized coal fired boiler in a power plant, belongs to the field of power generation of coal-fired boilers, and aims to realize stable operation of the pulverized coal fired boiler under ultralow load and meet the requirement of flexible peak regulation of a power grid. The method comprises the steps that raw coal is made into pulverized coal with the particle size smaller than 200 micrometers through a coal mill, wherein 1%-5% of the pulverized coal is carried by airflow to enter a combustion stabilizer; the temperature of the combustion stabilizer is controlled to be 800-1,100 DEG C by adjusting the air amount, and the pulverized coal is subjected to oxygen-deficient combustion and gasification reaction to generate high-temperature fuel gas; and the high-temperature fuel gas with unburnt pulverized coal is sprayed into the boiler through an ignition pipe, and the effect of stabilizing combustion of the pulverized coal in the boiler is achieved. The combustion stabilizer is composed of a nozzle, an electric heater, the ignition pipe, a heat-insulation fire-resistant lining and a shell. The method has the advantages of being simple in system, flexible to operate, good in coal type adaptability, high in response speed, low in operation cost and small in investment.

Description

technical field [0001] The invention relates to a method and device for ultra-low-load stable combustion of a pulverized coal boiler in a power plant, belonging to the field of coal-fired boiler power generation. Background technique [0002] Due to changes in weather, seasons, and day and night, wind and solar power generation has the characteristics of intermittency, volatility, and randomness, resulting in a huge peak-to-valley ratio of power generation. In order to solve the dilemma of new energy consumption, the flexibility transformation of thermal power, the use of coal-fired thermal power units for peak regulation is an inevitable demand for stable power supply. [0003] When pulverized coal boilers in power plants operate under deep peak-shaving and low-load operation, the calorific value of coal-fired coal is greatly reduced, and the furnace temperature is lowered, resulting in a decrease in the stability of pulverized coal combustion. At present, the low-load sta...

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Problems solved by technology

Chinese patents 201410467276.0 and 201010244692.6 respectively disclose a fuel and gas ignition and stable combustion system, but due to the high price of oil and gas, this method will tend to be replaced by oil-free stable combustion technology in the future

Chinese patents 201710109787.9, 201721294248.9, 201810192558.2, 201810867626.0, 201820453959.4, and 201710931919.6 propose improved burners, air inlet methods, coal inlet methods, and pulverized coal concentration separation to a certain extent, which can improve the combustion effect of the boiler to a certain extent, but cannot completely improve the combustion effect of the boiler. Meet the requirements of ultra-low load and stable combustion of boilers

The biggest difference of this type of technology is the choice of preheating method. The difficulty lies in the control of the preheating temperature. If the temperature is too low, it will not be effective; if the temperature is too high, it will easily lead to deflagration in the pipeline, and there is a safety hazard of explosion.

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