Starting-up method of circulating fluidized bed boiler

Abstract

The invention discloses a starting-up method of a circulating fluidized bed gasification furnace. The method comprises a furnace temperature-raising pressure-raising stage, a bed-layer construction preparation stage, a bed-layer construction stage and a synthesis gas treatment stage. The method has the advantages that when the method is applied to starting up of the furnace, temperature raising and pressure raising of the gasification furnace are carried out at the same time, and the problem that temperature raising and pressure raising cannot be carried out at the same time in a traditional gasification furnace starting-up method is solved; mixed gas without heating treatment is adopted as pulverized coal conveying gas and a fluidizing agent, so that pulverized coal in the gasification furnace is kept at a good fluidization state, slag-bonding accidents of the gasification furnace are avoided, the process of temperature raising and pressure raising is shortened, the furnace starting-up time is short, the amount of unqualified synthesis gas is small, resource waste is reduced, and the environmental protection load of enterprises is reduced; and the temperature raising process mainly depends on the furnace gas, the heat efficiency of the furnace gas is high, the use amount of the ignition pulverized coal is reduced, and the production cost of the enterprises is reduced.

Description

Technical field: [0001] The invention relates to the field of coal chemical industry, in particular to a method for starting a circulating fluidized bed gasifier. Background technique: [0002] At present, there are three types of fluidized bed gasification processes: coal pressurized catalytic gasification, ash fusion and U-gas, all of which adopt the traditional three-stage furnace start-up method of heating up the oven - feeding materials to build a bed layer - system boosting pressure. The heating and boosting processes must be carried out in strict accordance with the requirements. The traditional furnace start-up method has the following problems: 1. Oven process: the traditional furnace uses the flue gas generated by the combustion of liquefied petroleum gas or natural gas as the heat source. It takes about 24 hours for the furnace temperature to rise from room temperature to 850 °C, and the heating process takes a long time. 2. The process of feeding the material to...

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Problems solved by technology

The following problems exist in the traditional way of starting the furnace: 1. Oven process: The traditional method uses the flue gas produced by the combustion of liquefied petroleum gas or natural gas as the heat source. It takes about 24 hours for the furnace temperature to rise from room temperature to 850°C, and the heating process takes a long time. ;2. The process of feeding materials to build the bed layer: after the furnace temperature rises to 580°C, the gasification agent and pulverized coal are introduced into the furnace. Since the temperature of the pulverized coal itself is low, the furnace temperature will drop directly after being put into the furnace, resulting in The coal gasification reaction cannot be carried out normally; therefore, part of the pulverized coal input at this stage is burned to increase the furnace temperature, and the other part participates in the gasification reaction, but because the furnace temperature and pressure cannot meet the requirements of the gasification reaction, it is not completely gasified , can only be discharged out of the furnace along with the synthesis gas, resulting in low quality and high oxygen content of the synthesis gas, which cannot enter the follow-up section, and is prone to explosion when sent to the torch treatment, so it can only be discharged into the atmosphere, which is not only a serious waste of resources, but also Cause pollution to the environment; 3. Boosting process: Before the boosting process starts, it is necessary to heat-tighten the equipment and pipelines to ensure the airtightness of the equipment and pipelines, and then gradually increase the pressure from normal pressure to the predetermined pressure value according to the actual situation , because the fluidized state of the charge in the furnace will change drastically at the key points of boosting pressure (generally 1.0MPa, 2.0MPa, 3.0MPa), once an unstable flow pattern or local overtemperature occurs, it will lead to gasification Furnace slagging accidents; therefore, when rising from one critical point of pressure to another, not only the pressure increase rate is required to be gradually reduced, but also the duration of maintaining the higher pressure critical point is required to be continuously increased to ensure that the fluidized bed The bed temperature and pressure inside the gasifier are within a controllable range and have a good fluidization state; therefore, the boosting process lasts for a long time, generally taking several days

The above problems will become more and more obvious with the increase of the volume of the circulating fluidized bed gasifier. On the whole, the start-up process of the traditional circulating fluidized bed gasifier has long operation period, serious waste of resources, complicated process, great difficulty and serious problems. The problem of polluting the environment

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