Coal upgrading technology - AbsoluteAstronomy.com

Coal upgrading technology refers to a class of technologies developed to remove moisture and certain pollutants from low rank coals such as sub-Bituminous coal

Bituminous coal

Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than Anthracite...

and lignite

Lignite

Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...

(brown coal) and raise their calorific values. Companies located in Australia, Germany and the United States are the principal drivers of the research, development and commercialisation of these technologies.

Environmental rationale

Around 30 nations collectively operate more than 1,400 brown coal fired power stations around the world. Brown coal power stations that cannot economically dewater brown coal are inefficient and cause of high levels of carbon emissions. High emitting power stations, notably the Hazelwood power station in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, attract environmental criticism. Many modern economies including Greece

Greece

Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

and Victoria

Victoria (Australia)

Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

(Australia) are highly dependent on brown coal for electricity. Improved environemntal performance and the need for stable economic environment provide incentive for investment to substantially reduce the negative environmental impact of burning raw ('as mined') brown coal.

Economic rationale

Coal upgrading technologies remove moisture from 'as mined' brown coal and transform the calorific performance of brown coal to a 'cleaner' burning status relatively equivalent to high calorific value black coal. Some coal upgrading processes result in a densified coal

Densified coal

Densified coal is the product of the Coldry Process coal upgrading technology that removes moisture from low-rank coals such as sub-bituminous and lignite/brown coal. The densification process raises the calorific value of low rank coal to equal or exceed that of many export grade black coals...

product that is considered to be a Black coal equivalent

Black coal equivalent

Black coal equivalent is a term applied to describe the properties of an export coal product derived from the Coldry Process, a patented coal upgrading technology operated by Environmental Clean Technologies Limited, in Victoria, Australia...

product suitable for burning in black coal boilers.

Victorian brown coal with a characteristic moisture content of 60% by weight is regarded as the 'wettest' brown coal in the world. The high moisture content is the key reason why the state's three major power stations are collectively regarded as the dirtiest carbon emitters in the world. Studies undertaken by the University of Melbourne

University of Melbourne

The University of Melbourne is a public university located in Melbourne, Victoria. Founded in 1853, it is the second oldest university in Australia and the oldest in Victoria...

and Monash University

Monash University

Monash University is a public university based in Melbourne, Victoria. It was founded in 1958 and is the second oldest university in the state. Monash is a member of Australia's Group of Eight and the ASAIHL....

confirm that when moisture is removed from Victorian brown coal, naturally low levels of ash, sulfur and other elements rank it as being one of the cleanest coals in the world. When dewatered upgraded brown coal can compete in the export market at comparable prices to black coal.

With significant levels of brown coal mining occurring around the world, and mining levels increasing, the need for coal upgrading technologies has become more apparent. the technologies will help to address global environmental concern of rising emissions from the burning of brown coal and provide alternative fuel options to rapidly emerging economies such as Vietnam that face difficulty competing for black coal with China, India, Japan and other nations.

Lignite mined in millions of metric tons
Total	804.0	1,028.0	1,214.0	877.4	894.8
Country	1970	1980	1990	2000	2001
Germany	369.3	388.0	356.5	167.7	175.4
Russia	127.0	141.0	137.3	86.4	83.2
United States	5.4	42.3	82.6	83.5	80.5
Australia	24.2	32.9	46.0	65.0	67.8
Greece	8.1	23.2	51.7	63.3	67.0
Poland	32.8	36.9	67.6	61.3	59.5
Turkey	4.4	15.0	43.8	63.0	57.2
Czech Republic	67.0	87.0	71.0	50.1	50.7
People's Republic of China	13.0	22.0	38.0	40.0	47.0
Socialist Federal Republic of Yugoslavia	26.0	43.0	60.0	-	-
Serbia and Montenegro	-	-	-	35.5	35.5
Kingdom of Romania	14.1	27.1	33.5	17.9	29.8
North Korea	5.7	10.0	10.0	26.0	26.5

Technology comparison

Because of inherent high moisture content, all lignites need to be dried prior to combustion. Depending on the technology type drying is achieved either via a discrete operation or part of a process. The comparison chart identifies different technology drying methods that are in development in different countries and provides a qualitative comparison.

Option	Current Use	Coldry ProcessColdry Process, ECT Limited, Australia	RWE-WTARWE-WTE = RWE (Rhenish-Westphalian Electric) WTE technology	WEC-BCBWEC-BCB = White Energy Company, Binderless Coal Briquetting	UBCUBC = Upgraded Brown Coal Process, Japan Coal Energy Center & Kobe Steel Ltd.	Exergen CHTDExergen company, Continuous Hydrothermal Dewatering technology	MTEMTE = Mechanical Thermal Expression, developed by the CRC for Clean Power	KfuelKFuel = Koppelman Fuel, Evergreen Energy, Denver, Colorado, USA
Country of origin	n/a	Australia	Germany	Australia	Indonesia/Japan	Australia	Australia	United States
Process Description	mine lignite 'as is'. Combust untreated. Burn in standard brown coal boiler	exothermic reaction. natural evaporation. accelerated drying at 25-30°C	fluidised bed stream drying	flash dry coal fines. use pressure to form briquettes	mixing crushed coal with oil, heating the mixture to 130-160°C under 19-19.5 Bar pressure, separating the slurry cake from the oil by a centrifuge and then drying and briquetting it	Continuous Hydrothermal Dewatering decarboxylation reaction in slurry form at 300 degC and 100 Bar, followed by gas/liquid/solid separation and press drying	heat and squeeze at 250°C and 125 Bar, express water from coal	heat and squeeze at 200°C and 100 Bar
Drying Description	drying achieved in recirculated steam of boiler exhaust gases via high temperature	drying achieved using low temperature waste heat to provide evaporative drying	drying achieved using >100°C low pressure steam	drying achieved via exposure to high pressure combustion stream (flash drying)	drying achieved by exposure to 130-160°C under 19-19.5 Bar pressure in oil slurry	drying achieved by exposure to high pressure and temperature in a vertical autoclave, followed by a flashing step	drying achieved via high pressure and temperature compression	drying achieved via high pressure and temperature compression
Grade of heat used for drying	High	Low	Medium	High	Medium	Medium	High	High
Alternative uses for energy consumed in drying	steam generation	none	power generation	coal sales (fines used for combustion	n/a	electrical energy	electrical energy	electrical energy
Pretreatment requirement	crushing/screening (normal)	(normal) plus mechanical mastication and extrusion	(normal)	(normal)	crushing and mixing with oils	slurrying and high pressure pumping	(normal)	(normal)
CO2 exposures	high end exposure to CO2 - default position	Up to 40% reduction in CO2. Net beneficial CO2 position due to low heat and low pressure	Up to 30-40% CO2 reduction from the boiler. (Lost steam energy utilised in fluid bed dryer not accounted for)	zero net improvement due to energy source for drying is coal combustion	n/a	Up to 40% reduction in CO2	~15% CO2 reduction in combustion (detailed analysis not available). Zero net improvement, due to energy used for heating and compression	~15% CO2 reduction in combustion (detailed analysis not available). Utilises energy for heating and compression
Waste streams generated from drying	none	none	none	none	waste water stream	none	waste water stream	waste water stream
Byproduct streams possible	none	demineralised water	none	none	n/a	demineralised water	none	none
Coal output stream description	input coal for power generation only	coal pellets for use and export	input coal for power generation only	coal briquettes for use and export	coal briquettes for use and export	coal for use and export	input coal for power generation only	input coal for power generation only
Coal output moisture level	n/a	12-14%	12-14%	10-15%	n/a	5-10%	~18%	~20%
Coal output - transportable or exportable	n/a	non-pyrophoric	direct to boiler only	non-pyrophoric	non-pyrophoric	non-pyrophoric	pyrophoric	pyrophoric
Industrial maturity	status quo - well established	pilot plant operational for 7 years; extensive database of global testing; commencing feasibility for full scale commercial operation by 2014	commercial operations in several locations	one commercial scale plant, operations have not exceeded 30% of nameplate capacity	pilot plant operational	Pilot Plant 2002 - 2008, ready for commercialisation. Tested on Victorian and Indonesian coals	pilot plant abandoned	pilot plant operational

Environmental rationale

Economic rationale

Technology comparison

See also