Coal-water slurry fuel
Combustible mixture of coal particles in water
From Wikipedia, the free encyclopedia
Coal-water slurry fuel is a mixture of fine coal particles suspended in water. Such slurries are used to transport coal. Typically, the slurry is dried prior to combustion.[1] In principle but not in practice, coal slurries can be used to power boilers, gas turbines, diesel engines, and heating and power stations.
Characteristics
A coal-water slurry fuel is defined by a number of factors including its viscosity, particle size, rate of sedimentation, ignition temperature (800–850 °C [1,470–1,560 °F]), combustion temperature (950–1,150 °C [1,740–2,100 °F]), ash content and calorific value (3,700–4,700 kilocalories per kilogram [15.5–19.7 MJ/kg]).
When coal-water slurry fuel combusts, over ninety-nine percent of its carbon content is consumed.[citation needed] Coal-water slurry fuel is fire-proof and explosion-proof.[citation needed] Ash content of less than ten percent is desirable for boilers. For diesel engines, there is no limit.
| Parameters | І GRADE | ІІ GRADE | ІІІ GRADE |
|---|---|---|---|
| Coal content, % | ≥ 65 | 63–65 | 60–63 |
| Viscosity[clarification needed] | ≤ 1200 | ||
| Minimum energy yield (kcal/kg) | ≥ 4700 | 4420–4660 | 4000–4420 |
| Ash content, % | ≤ 6 | 6–8 | 8–10 |
| Sulfur content, % | ≤ 0.35 | 0.35–0.65 | 0.65–0.80 |
| Ash softening temperature[clarification needed] | ≤ 1250 | ||
| Particles of more than 300 μm, % | ≤ 0.05 | 0.05–0.20 | 0.20–0.80# |
| Particles up to 75 μm, % | ≥ 75.0 | ||
| Volatile content, % | > 30 | 20–30 | ≤ 20 |
Production
The production of coal-water slurry fuel involves the crushing of coal or coal sludge to particles between 10 and 65 micrometers diameter (standard crushers can be used); wet milling and homogenisation (with additives as required). The resulting product (coal slurry) is then prepared for intermediate storage or transport.[2]
Large particle coal-water slurry fuel can be used to produce steam in boilers. Smaller (under 80 micrometer) particle coal-water slurry fuel can be used in diesel engines with or without co-fuels. For example, low speed marine or modular power plant diesels can operate on pure coal-water slurry fuel whereas medium speed diesels such as locomotive engines may need diesel as a co-fuel which will act as an ignition source. Very small (5 to 10 micrometer) particle coal-water slurry fuel has been trialled in combined cycle gas turbine power plants. Smaller sized particles are more versatile in use but are more difficult to produce.[citation needed]
Prototypes
Converting coal into a liquid form may simplify the delivery and dispensing of the fuel. It may be a cost-efficient alternative to oil and natural gas. Separating non-carbonaceous material before making the slurry may reduce the production of ash to two percent.[citation needed]
Development
| Type of coal | Possibility |
|---|---|
| Brown coal (lignite) | possible, tested and confirmed |
| Flame coal (V=40–45%) | well developed[4] |
| Gas flame coal, gas coal (V=28–40%) | well developed |
| Fat coal – anthracite (V=7–28%) | possible, tested and confirmed |
Belovo Novosibirsk project
In the late 1950s, the Soviet Union looked for new methods of using coal sludge for power generation. Coal-water slurry fuel was made in a ball mill which pulverised the coal or coal sludge. This was done near a coal mine in Belovo, Siberia. The coal-water slurry fuel was transported through a pipeline to Novosibirskaya TEC-5, Novosibirsk, a distance of 262 km (163 mi). The pipeline had three intermediate pumping stations. The Belovo Novosibirsk project used coal-water slurry fuel in steam boilers at a rate of 1340 tonnes per hour.[5] There was a further project at Belovo Novosibirsk between 1989 and 1993 and development of coal-water slurry fuel technology for district heating stations and power stations.[6] In 2004, a coal-water slurry fuel production plant was opened at Enskiy village, Murmansk.[7]
Austria
In 2012, the Austrian company, Effective Energy Technology GmbH (EET) built facilities for production and combustion of coal-water slurry fuel in Europe. Examples of the technology in practice are hydroshock type wet-milling devices and standard water boilers equipped with swirl pre-chamber and coal-water slurry nozzle.,[8][9][10] developed by group of companies EET.
Ukraine
Verkhovna Rada requested China Development Bank credit for the implementation of coal-water slurry fuel technology.[11] Ukteplokom, a state owned entity, commenced operation.[12][13]