Coal-water slurry fuel

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

Coal-water slurry fuel, Grade III

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

Ball mills for production of coal-water slurry in Russia

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

Combustion of coal water slurry fuel in a steam boiler, Murmanskaya region, Russia.[3]

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

Coal water slurry fuel production machine in 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]

See also

References

  1. ^ Hower, James (2016). "Coal". Kirk-Othmer Encyclopedia of Chemical Technology. pp. 1–63. doi:10.1002/0471238961.0315011222151818.a01.pub3. ISBN 978-0-471-48494-3.
  2. ^ "Water-coal slurry as an alternative to natural gas and heavy fuel oil"
  3. ^ Горение ВУТ в котле ДКВР-6,5-13. Видео 1. Archived from the original on 2021-12-15.
  4. ^ Production of CWS, video[dead link‍]
  5. ^ "Belovo-Novosibirsk project." Archived 2016-03-05 at the Wayback Machine Vodougol.ru archived 5 February 2015.
  6. ^ "ЖИДКИЙ УГОЛЬ; Блог о Водоугольном Топливе." Archived July 12, 2009, at the Wayback Machine Liquidcoal.ru |Accessed 30 March 2013 in Russian. Dead link.
  7. ^ "Водоугольное топливо в пос. Ёнский" Archived May 19, 2014, at the Wayback Machine Vodougol.ru
  8. ^ "Coal water slurry production unit" cwstech.at in English.
  9. ^ "CWS production and combustion process"
  10. ^ "CWS swirl combustion technique"
  11. ^ "Китай даст Украине денег на замену российского газа углем". Archived from the original on 2014-07-14. Retrieved 2014-06-10. Forum.for-ua.com. Dead link.
  12. ^ "Energy of Nature" ukrproject.gov.ua.
  13. ^ Biletsky V. et al "Fundamentals of highly loaded coal water slurries." CRC Press, Taylor and Francis Group, London, UK. A Balkema Book 2013 pp. 105–14.