Coal gas-steam combined production method and apparatus of double-circulation fluidized bed

Abstract

The invention relates to coal gas-steam cogeneration method and opposite furnace. Wherein, fuel burns in combustion chamber to generate smoke gas, the latter enters heat exchanger after cyclone separator to generate steam; some cycle dust collected by cyclone separator returns to chamber, other enters vaporizer; fuel takes pyrogenic gasification reaction to generate coal gas with reacted product back to chamber; the cogeneration furnace has double-cycle fluidized bed loop, wherein, the burning loop composes of a chamber, a smoke gas separator, and a refeeding device; the gasification loop composes of a gasification room, a coal gas separator, and a refeeding device; two loops are coupled by hot dust allocator and refeeding device. The running mode is flexible, and also fit to treat carbon-containing waste.

Description

technical field [0001] The invention relates to a double-circulation fluidized bed gas-steam cogeneration method and a double-circulation fluidized bed gas-steam cogeneration device. technical background [0002] Existing coal-fired boilers and gasifiers can only produce steam or coal gas alone, while existing coal gas-steam cogeneration boilers often only ensure the stability of gas production, but cannot guarantee the stability of steam production at the same time. For fluidized bed gas-steam cogeneration equipment, there are two types of coal gasification chambers commonly used: moving bed coal gasification chamber and bubbling bed coal gasification chamber. In the moving bed coal gasification chamber, the circulating ash is not easy to mix evenly with the coal, which restricts the improvement of the carbon conversion rate; in addition, the semi-coke in the gasification chamber is often returned to the combustion chamber by gravity, which cannot control the material in th...

AI Technical Summary

Problems solved by technology

Part of the circulating material returns directly to the furnace, and part of it enters the retort; however, the retort operates in a moving bed mode, and the circulating ash and coal are added separately, which is difficult to mix evenly and the gasification efficiency is not high; the coal fed into the retort enters the furnace through the retort, Short reaction times in the retort; in addition, material distribution is achieved through mechanical valves, which have low reliability

[0005] Chinese utility model patent 01230778.5 provides a circulating fluidized bed pulverized coal gasification gasifier with double fluidized beds, a flue gas separator behind the fluidized bed combustion furnace, and a gas separator behind the fluidized bed gas furnace , but all materials have to flow through the gas furnace, gas separator, combustion furnace and flue gas separator in sequence, so the combustion and gasification do not have a separate circulation loop, but a series circulation of the combustion loop and the gasification loop, not Strictly speaking, double circulating fluidized bed; the heat required for the circulating gasification reaction is brought into the gas furnace through the hot material generated by combustion; the furnace only supplies gas and cannot produce steam at the same time

In addition, the size of coal particles after gasification is small, and some coal particles will be discharged with flue gas or coal gas before being burned, which reduces the carbon conversion rate; all materials are alternately passed through the gas furnace and the combustion furnace. The operation mode requires that the coal particles must be finer to be brought out at one time, which is very different from the conventional circulating fluidized bed (the material particle size is between 0-10mm), so that the multiple cycles and multiple combustions of the circulating fluidized bed cannot be utilized The role of the system, and it is difficult to adjust the system, and the gasification efficiency and combustion efficiency are bound to be low

In addition, the transportation of hot and cold materials is completed by a mechanical screw conveyor, which reduces the reliability of the system operation

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