Coke oven gas is combustible by-product gas produced during coal coking. Its main components are H2 (50% to 59%), CH4 (21% ~ 28%), CO (6% ~ 12%), CO2 (2% ~ 5%), N2 (2% ~ 5%) and small quantity of oxygen, benzene, naphthalene, ammonia, tar, sulfide, cyanide etc. After purification, coke oven gas can be used in many ways: industrial and civil fuel (heating and power generation), reducing agent (direct reduction of iron making), chemical raw materials (mainly used in synthetic ammonia and methanol production) and hydrogen.
In order to get qualified products (SNG/CNG/LNG) made from coke oven gas, content of CO2 must be reduced to below the specified value during the production process, so that devices can operate in stable, and ensure product quality. CO2 removal and CH4 concentration is achieved through methanation reaction and gas separation technology (such as PSA), or combination of the two technologies. Methanation not only reduces the carbon dioxide in the gas, but also increases CH4, and thus produces more products.
After removal of benzene, naphthalene, sulfur and other impurities through purification, Coke oven gas continue with the process of methanation reaction under the action of catalyst to convert CO, CO2 and H2 into rich methane gas which is mainly composed of CH4, H2 and N2. Though gas separation technology, hydrogen is separated from rich methane gas and get synthetic natural gas (SNG) whose content of CH4 is more than 85%. By further processing and compression, SNG is converted into compressed natural gas (CNG). SNG can also be liquefied to acquire natural gas (LNG).
The production of liquefied natural gas (LNG) by using coke oven gas as raw material is to separate methane from coke oven gas (content: 28% ~ 20) and convert it to liquefied natural gas. The whole process is composed of following units:
- Tar, sulfur, benzene and naphthalene removal unit;
- Acid gas (CO2, H2S, HCN) removal unit;
- Desulfurization unit;
- Hydrogen separation unit;
- Deep purification unit;
- Liquefaction unit;
- Product storage unit;
We own patented technology of purification and separation.
The following is 25000Nm3/h LNG production from COG factroy in Gaocheng city. This factory was successfully commissioned at its first test run.