CN1262735C - Process for gasifying underground coal - Google Patents

Abstract

The present invention discloses novel underground coal gasification technology for filling coal powders or sandy soil from outside, which belongs to the production of underground coal gas. In the present invention, a U-shaped gasification furnace with an air flow channel and a gasification channel is formed in an underground coal bed through digging. The underground coal bed is ignited firstly in the process of gasification, and while air is blown into the air flow channel, fine coal powders or sandy soil is filled into the gasification channel in a flow jetting mode to combust with the underground coal bed simultaneously. After combustion, coal slag is utilized to fill a combusted area to keep the space of the combusted area within a certain range, so that the high temperature condition of the combusted area is kept, and the catalytic action of the coal slag is performed. As a result, the yield and the quality of coal gas are raised, the service life of the coal bed is extended, and the economic benefit is raised substantially.

Description

Gasifying underground coal technology

Technical field

The present invention relates to the coal underground gasification technology category, particularly directly burnt in underground unprofitable coal seam and produce a kind of process for gasifying underground coal that adds fine coal or sand of coal gas.

Technical background

Existing gasifying underground coal technology is to dig air-flow and gasification tunnel in the coal seam, be blown into air from the air communication road junction on the ground, oxygen enrichment and steam, and light subterranean coal, constantly burning in the coal seam, makes the coal seam in the gasification tunnel of bottom that chemical reaction at high temperature take place, and produce great number of flammable gas, as industry, domestic energy, this kind method simple possible.Because subterranean coal constantly burns, the space of combustion dead zone is constantly enlarged, cause the gasification tunnel temperature under the coal seam to reduce, and reduced the output and the quality of coal gas.

Summary of the invention

The object of the present invention is achieved like this, a kind of gasifying underground coal technology, its feature in: dig out the U-shaped gasification furnace under the coal seam in desire gasification, and light underground coal bottom in the underground gasification passage earlier, and drum advances gasifying agent in gas channel, the subterranean coal burning remains on more than 1000 ℃ the interior temperature of the gasification tunnel of underground gasification furnace, produces high-quality coal gas.Because of subterranean coal constantly burns, the space of combustion dead zone is constantly enlarged, cause temperature reduction in the gasification tunnel, when output that influences coal gas and quality, just begin in defeated coal pipe, to carry fine coal or sand, together burn with underground entity coal seam, stay the filler of down-hole as the combustion dead zone behind these coal combustions, simultaneously, the space of combustion dead zone should remain on the temperature that can make gasification tunnel and remain in the scope more than 1000 ℃, again because contain a large amount of metal oxides in the cinder, as Fe ₂O ₃, Fe ₃O ₄, Al ₂O ₃, SiO ₂Deng all being the catalyzer of coal gasification, strengthen the oxidation-reduction reaction in the gasification tunnel; Can improve methanation reaction again, accumulated the imflammable gas based on coal gas in gasification tunnel, these gases are collected storage on the ground, pass through desulfuration again, and dephosphorization is clean fuel after handling.

The described granularity that adds fine coal or sand is below 1mm, and the pressure of air blast must be brought fine coal or sand into gasification tunnel with mode of jet greater than existing pressure and resistance of ducting sum in the stove, the cinder filling combustion dead zone behind the pulverized coal friring.

The described gasifying agent that blasts gas channel is air, water vapour or oxygen, steam or carbon dioxide.

The present invention is compared with prior art: in the subterranean coal combustion process, bring fine breeze in the time of air blast inward into, promote the burning of subterranean coal, cinder behind the pulverized coal friring is as the inserts of combustion dead zone, having solved in the prior art descends the gasification tunnel temperature because of the combustion dead zone that causes behind the coal burning enlarges, influence the output and the quality problems of imflammable gas, this technology can improve underground gasification furnace temperature and control combustion space, dead zone effectively, furnace temperature is remained on more than 1000 ℃, thereby gas quality and output are improved, and keep relative stability, owing to injected water vapour simultaneously, also will significantly improve the quality and the output of coal gas, because of the resolution ratio of water vapour is about 50%, the water yield of residue can be used as the curing compound of sand and flyash, reduces the discharge value of water outside stove.The adding of fine coal is invisible has in addition thickeied girdle, and reduced the consumption of filler, simultaneously, the space of combustion dead zone should remain on the temperature that can make gasification tunnel and remain in the scope more than 1000 ℃, this is to improving furnace temperature, keeping oxidized zone to move forward and stable yield all is effective, and the length of service that has prolonged underground gasification furnace, especially the thick girdle in the 0.8m left and right sides is had bigger effect.Contain the catalyzer that a large amount of metal oxides is coal gasification in the cinder, when H2 is dense, can improve methanation reaction.Prolonging the length of service of underground gasification furnace, is the most effective method that reduces cost, and adds fine coal and be converted into coal gas and can appreciate, and through estimation, the profit in 1 year of a gasification furnace can be up to 900,000 yuan, so this technology has very high economic benefit.

The specific embodiment

Below in conjunction with embodiment the present invention is further specified.

Embodiment: the present invention is the process for gasifying underground coal that adds fine coal.Under the coal seam of desire gasification, dig out the U-shaped gasification furnace, when adding the design of coal dust underground gasification furnace outside, must consider will have certain gradient between gas channel and the coal seam, for example, when the gas channel in horizontal coal seam adopts the boring method construction, at the gas channel of surface layer rock section and the gas channel in horizontal coal seam, must have certain gradient and radian, could constitute a straightway pulverized coal channel.The underground gasification process of its coal is earlier the coal seam to be lighted underground, constantly air blast in gas channel from the ground, air, water vapour or oxygen, water vapour or carbon dioxide are blasted gas channel and gasification tunnel, and coal burning produces the cracking in the high-temperature gasification stove of carbon dioxide, carbon monoxide, water vapour and produces H under hot conditions ₂+ CO promptly produces in gasification furnace and gathers great number of flammable gas, and these gases are collected storage, and then through after desulfurization, the dephosphorization treatment, just become clean fuel; The continuous burning in coal seam in gasification, combustion space, dead zone is constantly enlarged, area of dissipation increases, cause temperature to reduce, the gas yield and the quality of gasification are reduced, at this moment just in air blast, allow bigger blast add coal dust with mode of jet, about 400～500kg/ hour fine breeze, burn simultaneously with the coal seam, underground gasification furnace is except that burning entity coal, also at burning loose coal, can keep furnace temperature more than 1000 ℃, stay the filler of down-hole behind these coal combustions, reduced the consumption of filler, simultaneously as the combustion dead zone, the space of combustion dead zone should remain on the temperature that can make gasification tunnel and remain in the scope more than 1000 ℃, and this all is effective to improving that furnace temperature and oxidized zone move forward.Contain a large amount of metal oxides in the cinder, as Fe ₂O ₃, Fe ₃O ₄, Al ₂O ₃, SiO ₂Deng being the catalyzer of coal gasification all, work as H ₂When dense, can improve methanation reaction.Prolonging the length of service of underground gasification furnace, is the most effective method that reduces cost, and adds fine coal and be converted into coal gas and can appreciate, so the present invention has very high economic benefit.

Claims (3)

1. An underground coal gasification process, characterized in that: a U-shaped gasifier is excavated under the coal seam to be gasified, and the underground coal bottom layer in the underground gasification channel is first ignited, and air is blown into the air flow channel Chemical agent, the combustion of underground coal seams keeps the temperature in the gasification channel of the underground gasifier above 1000°C, and when the output and quality of gas are affected, the pulverized coal or sand will be transported from the coal pulverized pipe to meet the underground solid coal seam. At the same time, the space of the burn-out area should be kept within the range that can keep the temperature of the gasification channel above 1000°C. In the gasification channel, combustible gases mainly gas are accumulated, and these gases are stored on the ground. After being collected and stored, and then desulfurized and dephosphorized, it becomes a clean fuel. 2. The underground coal gasification process according to claim 1, characterized in that: the particle size of the added pulverized coal or sand is below 1 mm, and the pressure of the blast must be greater than the sum of the existing pressure in the furnace and the pipeline resistance, The pulverized coal or sand is brought into the gasification channel by jet flow. 3. The underground coal gasification process according to claim 1, characterized in that: the gasification agent blown into the gas flow channel is air, water vapor or oxygen-enriched, water vapor or carbon dioxide gas.