菜单
关闭
|
Coal Gasification Gas, refer to the combustible gas produced by the chemical reaction of coal or coke with gasifying agents (such as air, oxygen, water vapor) at high temperatures. The main components include hydrogen (H₂), carbon monoxide (CO), and a small amount of methane (CH₄). Typical gasification gases include Producer gas, Water gas, and Semi-water gas, etc.
Gasification Gas is a kind combustible gas which is produced by crushing, pressure and pyrolysis of fuel coal. It is a combustion mode of clean coal utilization technology. The calorific value of coal gas is lower than that of natural gas, but its preparation is convenient. It can be produced by own equipment without restriction of transportation pipeline. At present, Gasification gas is an irreplaceable flammable gas in the utilization of clean energy. Because of its many advantages, coal gas has been widely used in industrial and mining enterprises, and can be used for power generation and domestic gas.
Coal gasification technology is one of the main ways to produce syngas products. Solid coal is converted into gaseous syngas through gasification process, meantime, by-products such as steam and ash are produced. In coal gasification, there must be three conditions: gasifier, gasifying agent and heat supply. Coal gasification technology can be divided into three categories: fixed bed gasification, circulating fluidized bed gasification and entrained-flow gasification technology. All kinds of gasification technology have their own advantages and disadvantages, and have certain requirements for the quality of raw coal. The advanced technology and maturity degree of technology are also different.
The composition and content of gasification gas vary depending on the gasification agent used.
1. Producer Gas, refers to a combustible gas produced by high-temperature gasification of coal or coke with gasifying agents (air and water vapor) in a gasifier. The Lower heating value (LHV): about 900 - 1600 kcal/Nm³, commonly used as industrial heating fuel, can be directly used for power generation. Including: Air producer gas and Mixed gas.
1.1 Air Producer Gas, refers to a gas fuel produced intermittently (while maintaining furnace temperature) by using air (mainly oxygen) as a gasifying agent and passing it through a high-temperature coal or coke layer for gasification reactions. Due to the large amount of nitrogen in the air, the proportion of non combustible components in the generated gas is high and the calorific value is low.
The main combustible components are CO (33% - 37%), CH₄ (< 1%), and H₂ with little or no content. The non combustible components are N₂ (64% - 66%) and CO₂ (0.5% - 1.5%). The Lower heating value (LHV) is about 900 - 1200 kcal/Nm³, and it is currently less commonly used.
1.2 Mixed Producer Gas, refers to a gas fuel produced continuously through gasification reaction with coal or coke under high temperature conditions, using a mixture of air and water vapor as a gasifying agent. The hydrogen content has increased, but it is still diluted by nitrogen gas, with a calorific value between air gas and water gas. Suitable for various industrial furnaces and can also be used as fuel for power generation.
The main components of Mixed Producer gas (air+steam gasification) after desulfurization treatment are CO (20% - 25%), H₂ (10% - 15%), CH₄ (0.3% - 1%), CmHn (0.7% - 2%), CO₂ (8% - 12%), N₂ (50% - 55%), O₂ (0.1% - 0.5%). The Lower heating value (LHV) range: 5.0 - 6.7 MJ/Nm³ (1200 - 1600 kcal/Nm³), It belongs to low-heating value industrial fuel gas.
2. Water Gas, also known as Coal to syngas, refers to a gas fuel produced by the gasification reaction of hot coal with water vapor as a gasifying agent at high temperatures. The main components are CO and H₂, with high calorific value but high production cost. Water gas is the raw material gas for producing synthetic fuels, which can be used to produce synthetic ammonia, hydrogen, and synthetic fuels. It can be directly used as a fuel for power generation.
The main components of Water gas (steam+coke gasification) are: CO (37% - 40%), H₂ (40 - 42%), CH₄ (0.5% - 1%), CO₂ (5% - 8%), N₂ (≤ 1%). The LHV range: 10 - 11.3 MJ/Nm³. belonging to high calorific value chemical feed gas.
3. Semi Water Gas, refers to a combustible gas produced by alternately blowing air and a suitable amount of water vapor into a gas generator using coal or coke as fuel. Combining the characteristics of air gas and water gas, it is a commonly used raw material gas in industrial ammonia synthesis and can be directly used as fuel for power generation.
The main components of Semi-water gas (air and steam alternately blown into the gasifier for gasification) are CO (18% - 20%), H₂ (50 - 55%), CH₄ and trace hydrocarbons (0.5% - 1%), N₂ (22% - 23%), CO₂ (5% - 8%), O₂ (< 0.5%). The LHV range: 9.8 - 10.5 MJ/Nm³, belonging to the feed gas specially designed for ammonia synthesis.
Gas requirement of Manufactured gas ：
● Gas calorific value ≥ 4.0 MJ/Nm³(Non pressurized sets); Gas temperature ≤ 40℃.
● Gas pressure 2.5-10 kPa; Pressure change rate ≤ 1 kPa/min.
● Hydrogen content (H₂ Volume) ≤ 60% (Non pressurized sets); Hydrogen content (H₂ Volume) ≤ 20% (Pressurized sets);
● Oxygen content (In hydrogen containing gas) ≤ 1%.
● Moisture content ≤ 40 g/Nm³，no free water.
● Impurity content ≤ 30 mg/Nm³; Impurity size ≤ 5 μm.
● Tar content ≤ 50 mg/Nm³.
● H₂S ≤ 50 mg/Nm³; Total sulfur content ≤ 100 mg/Nm³.
● NH₃ ≤20 mg/Nm³;
● C₆H₆ ≤ 50 mg/Nm³.
● C₁₀H₈ ≤ 50 mg/Nm³.
● Halogen compounds ≤ 50 mg/Nm³.
