Process for fluidized bed classification gasification of dust coal

Abstract

The invention provides a process for graded gasification of a fine coal fluid bed, which comprises feeding fine coal the particle size of between 0 and 6 millimeters and a small amount of limestone to a circulating fluidized bed to react with an oxidizer and water vapor at a temperature of between 800 and 1,100 DEG C so as to generate water gas. The water gas generated through gasification is treated by two-stage gas-solid separation, wherein high-temperature coarse semi-coke of the first stage separation is returned to the circulating fluidized bed to react continuously; while high-temperature fine semi-coke of the second stage separation is sent to an air flow bed communicated with the lower part of the fluid bed and enters the air flow bed tangentially under the carrying of the water vapor and the oxidant so as to react at a temperature of between 1,300 and 1,500 DEG C. The high temperature gas generated by the air flow bed rises into the circulating fluidized bed to provide heat for the fluidized bed; and the residue is in liquid state, is discharged out at high temperature from a slag-off opening of the air flow bed, and is crushed as cement after chill heat exchange.

Description

1. Technical field [0001] The invention provides a pulverized coal fluidized bed staged gasification process, which belongs to the field of coal chemical industry. 2. Background technology [0002] Coal gasification is the leader of clean coal chemical technology and the leading technology for the development of coal direct liquefaction, indirect liquefaction, synthetic alcohol ether fuel and other chemicals and high-efficiency power generation. Coal gasification technology is mainly divided into fixed bed block coal gasification technology, fluidized bed pulverized coal gasification technology and entrained bed gasification technology according to the gasification method. In addition, there are slag bed, dissolved salt bed and iron bed coal gasification under development. method, hydrogenation gasification method, coal gasification method using nuclear energy, underground gasification method, etc. [0003] Fixed bed (moving bed) coal gasification technology is characterize...

AI Technical Summary

Problems solved by technology

[0003] Fixed bed (moving bed) coal gasification technology is characterized by lump coal air steam gas generation; its advantages are mature technology, less equipment investment and lower gasification cost, especially intermittent fixed bed coal gasification does not require pure oxygen, water Synthetic gas without nitrogen can be obtained by steam and air gas generation; its disadvantages are high residual carbon content in coal ash (10% to 30%), strict restrictions on coal types, gasification of high-quality lump coal, resulting in high raw material costs for many enterprises , high production costs

[0004] Fluidized bed pulverized coal gasification technology is characterized by continuous gas generation from pulverized coal with oxygen and water vapor; its advantages: direct use of various cheap pulverized coal as raw materials, moderate gas production capacity, high gasification efficiency, less environmental pollution, and equipment High investment and low cost of gas production; its disadvantages: large amount of fly ash and high residual carbon content (20% to 30%), high residual carbon content in coal ash (5 to 15%), which means vomiting and diarrhea.

[0005] Entrained bed coal gasification technology is characterized by continuous gas generation from finely pulverized coal, oxygen and water vapor, and liquid slag discharge; its advantages are high coal gas production capacity, high gasification efficiency, less environmental pollution, high equipment investment, and residual carbon content in coal ash Higher (2-7%), low gas production cost; its disadvantages are high requirements for coal fineness, high energy consumption for crushing; high reaction temperature (about 1400°C) and short time (several seconds) but feed coal powder cannot be predicted Heat, high oxygen consumption, unreasonable energy utilization, especially the high oxygen consumption of coal water slurry feed, low effective utilization of carbon