Stream | Destination | Typical quantities, based on 1 million tons per year coke |
Coke Oven Gas | Used as fuel gas at the coke oven battery and steel works | 50 million std.cu.ft./day |
Flushing Liquor | Recirculated back to the coke oven battery | Varies with plant design |
Waste Water | Discharged to treatment plant | Varies with plant design |
Tar | Sold as product | 29,000 gallons/day |
Ammonia/Ammonium Sulfate | Sold as product | 12 tons/day (as ammonia) |
Light Oil (if recovered) | Sold as product | 12,500 gallons/day |
Sulfur/Sulfuric Acid (if gas is desulfurized) | Sold as product | Varies with coal properties and local requirements |
"The 120 000 t/a methanol project based on coke oven gas designed by the Second Design Institute of Chemical Industry started production in Kingboard (Hebei) Coking Co., Ltd. on Sept. 5. The product reached the standard for AA-grade products in the United States. The capacity of this unit is 40 000 t/a higher than the first methanol unit based on coke oven gas in China complete in Qujing, Yunnan province in December 2004."
What all this adds up to is this:
In both indirect and direct (i.e., WVU's West Virginia Process) technologies for converting coal into liquid hydrocarbons suitable for fuel and plastics manufacturing, the coal, and it's intermediate products, must be "hydrogenated". WVU, in their direct coal liquefaction technique, as we understand it, use the solvent tetralin as the hydrogen donor.
Indirect CTL processes, such as Fischer-Tropsch and Bergius, use hydrogen derived from the coal itself, but there isn't enough to "go around". Much carbonaceous "slag" is generated, and a lot of the carbon is wasted. It has been suggested, perhaps in some places experimented with or reduced to practice, that the inclusion of biomass, or even pure hydrogen electrolyzed from water, could enable the necessary hydrogenation.
Herein, we have illustrated the possibility that an otherwise objectionable, hydrogen-rich by-product of coal use in the steel industry, coke oven flue gas, can be captured and recycled, as is, according to the above citation, apparently being done in China, into the process of converting coal into liquid hydrocarbon fuels.
We'll note also the co-production of fertilizer (ammonia), as well as other materials from which potential fuels could be derived - tar and light oil - in the coke-making process.
So, the possibility exists, as might be being realized in China, given the steel-making companies publicly known to be involved in their massive CoalTL industrialization program, to site, in an efficient and environmentally-beneficial way, a coal-to-liquid conversion facility next to a steel mill with an integral coking plant, to utilize coke oven gas as a co-feed in the synthesis of liquid hydrocarbon fuels, such as methanol, from coal.
As we've said many times: Our use of coal doesn't generate pollutants, just valuable by-products.