Carbontec Energy Corporation of Bismarck, North Dakota, has developed two coal technologies that may have an application to reduce moisture from North Dakota lignite, providing a low-moisture, high-BTU product:
Carbontec Energy Corporation owns an exclusive worldwide license to a unique coal pellet process, the CarbontiteTM Synthetic Coal Process. This process utilizes the Carbontite binder that reacts chemically with finely sized coal to produce low-moisture coal pellets from high-moisture coal feedstock with moderate, low-temperature pellet curing heat requirements. According to the company, the advantages of the Carbontite Cold Briquetting Process include:
Initial testing on Eastern bituminous coal-pond fines produced low, 9 to 10 percent moisture, high energy, 12,000 to 12,500 BTU pellets and briquettes from 23 percent moisture, 10,400 BTU per pound raw coal feedstock.
Carbontec Energy has also produced low-moisture Carbontite pellets from subbituminous, lignite and brown coal. Pilot-scale tests conducted on one-eighth by zero mesh subbituminous coal containing 28 percent moisture and 8,700 BTU per pound produced Carbontite pellets that assayed 10 percent moisture and 11,000 BTU per pound.
High quality Carbontite pellets were also produced from Indonesian subbituminous coal. Indonesian subbituminous coal containing 23.0 percent moisture and 8,520 BTU per pound produced Carbontite pellets that assay 6.48 percent moisture and 11,400 BTU per pound.
Carbontite bench-scale tests on 100x0 mesh North Dakota lignite that contained 33.2 percent moisture and 6,800 BTU per pound, produced Carbontite pellets assaying 4.4 percent moisture and 10,330 BTU per pound.
Loy Yang Brown Coal is a high-moisture, soft, earthy type Australian coal, containing 64.0 percent moisture and 3,840 BTU per pound. Carbontite pellets produced from Loy Yang coal assayed 7.8 percent moisture and 10,010 BTU per pound.
The United States Internal Revenue Service issued a favorable Private Letter Ruling on October 24, 1997, ruling that the synthetic fuel produced by the Carbontite process qualifies for Section 29 tax credits.
Carbontec Energy Corporation has issued a sublicense to three companies, who have constructed three Carbontite synthetic coal plants. One plant is located at the Cook coal terminal owned by American Electric Power on the Ohio River in Illinois. The other two plants are located near Peabody Coal Company mines in Kentucky and Southern Indiana. The three Carbontite synthetic coal plants placed in operation during June 1998 have a combined design capacity of 2.4 million tons per year.Carbondry Synthetic Coal Process
Carbontec’s CarbondryTM Process, efficiently and economically converts high-moisture, low-sulfur subbituminous coal into a high-BTU, low-moisture, low-sulfur, low-nitrous-oxide coal by removing a significant percentage of the moisture from the coal. The high-BTU, low-moisture, low-sulfur characteristics of Carbondry synthetic coal will enable utilities and industrial companies that have not installed scrubbers to comply with Phase I and Phase II of the Clean Air Act without incurring the derate typically associated with burning Powder River Basin subbituminous coal in boilers that were designed to burn high-BTU, low-moisture Appalachian, Colorado or Utah bituminous coals.
The Carbondry Process involves two stages--a hot oil first-stage reactor and a hot inert gas second-stage reactor. Raw coal is delivered on a steel mesh conveyor through the first-stage reactor which processes the coal bed with hot oil. The hot oil process in the first-stage reactor removes all of the surface moisture and a major portion of the inherent moisture and leaves a protective coating of oil on the coal. The second-stage reactor causes cross-linking and other important chemical changes in the coal and also controls the final BTU and moisture content. The synthetic coal, in addition to being a low-moisture, high-BTU fuel, is resistant to moisture reabsorption, dust generation and spontaneous combustion. Because the Carbondry Process operates at atmospheric pressures and moderate temperatures ranging from 300º to 700ºF, the plant can be constructed largely with off-the-shelf materials.
More than 2,000 tons of North Dakota lignite coal, Wyoming, Montana and Indonesian subbituminous coal have been successfully processed in Carbontec’s pilot plant in Bismarck, North Dakota.
The 20-ton per day demonstration plant began operating in May 1989, successfully converting 6,100 BTU, 40 percent moisture, raw lignite coal from a mine in North Dakota into a 10,500 BTU, 10 percent moisture CarbondryTM Synthetic Coal. After the successful lignite test, Carbontec Energy tested subbituminous coal from mines in Wyoming, Montana and Indonesia. The pilot plant program was effective in converting 8,450 BTU, 30 percent moisture, Powder River Basin subbituminous coal into 11,300 to 11,600 BTU, 8 percent moisture, 0.80 pounds SO2 per million BTU CarbondryTM Synthetic Coal. In all, Carbontec Energy has tested 16 different coals from five states and six foreign countries with similar successful results.
During 1995 Carbontec Energy Corporation entered into a joint test program with a major utility, to process subbituminous coal from a Powder River Basin mine in the Carbontec pilot plant at Bismarck. The Carbontec Synthetic Coal product produced was shipped for evaluation to the utility’s designated combustion test facility. The Carbontec coal shipped for this test was a high-quality, low-sulfur, low-NOx compliance coal.
The test program was successful in meeting and in some cases exceeding expectations. Carbontec Synthetic Coal handled well during loading, transportation, unloading and stockpiling as well as in the rehandling and grinding process. The coal burned well with good flame characteristics, producing low SO2 and NOx emissions. Test results were compared to a base central Appalachian coal currently being burned by the utility. The Carbontec Synthetic Coal produced lower SO2 than the base coal. In addition, NOx emissions produced with Carbondry coal were 40 percent less than the emissions of the central Appalachian coal.
A Carbondry plant is designed in module form. A typical plant module will produce 550,000 tons of product per year. Engineering has been completed for a two-module plant that will produce 1.1 million tons per year of synthetic coal product.