Refined coal

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Refined coal is the product of the application of a coal-upgrading technology that removes moisture and certain pollutants from lower-rank coals such as sub-bituminous and lignite (brown) coals and raising their calorific values. [1] Coal refining or upgrading technologies are typically pre-combustion treatments and/or processes that alter the characteristics of a coal before it is burned. The goals of pre-combustion coal-upgrading technologies are to increase efficiency and reduce emissions when coal is burned. Depending on the situation, pre-combustion technology can be used in place of or as a supplement to post-combustion technologies to control emissions from coal-fueled boilers. [2] A primary benefit of refined coal is the capacity to reduce the net volume of carbon emissions that is currently emitted from power generators and would reduce the amount of emissions that is proposed to be managed via emerging carbon sequestration methodologies. Refined coal technologies have primarily been developed in the United States, several similar technologies have been researched, developed and tested in Victoria, Australia, including the Densified coal technology ( Coldry Process) developed to alter the chemical bonds of brown coal to create a product that is cleaner, stable (not prone to spontaneous combustion), exportable and of sufficiently high calorific value to be a black coal equivalent.

Coal-upgrading technology

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 and lignite ( 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.[ citation needed]

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, attract environmental criticism. Many modern economies including Greece and Victoria (Australia) are highly dependent on brown coal for electricity. Improved environmental 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 product that is considered to be a Black coal equivalent 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 [3] and Monash University 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[ citation needed]
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
  SFR Yugoslavia 26.0 43.0 60.0 - -
  Serbia and Montenegro - - - 35.5 35.5
  Romania 14.1 27.1 33.5 17.9 29.8
  North Korea 5.7 10.0 10.0 26.0 26.5
Total 804.0 1,028.0 1,214.0 877.4 894.8

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 Drycol ZEMAG [note 1] Coldry Process [note 2] RWE-WTA [note 3] HTFG [note 4] WEC-BCB [note 5] UBC [note 6] Exergen CHTD [note 7] MTE [note 8] Kfuel [note 9] LCP [note 10] [4]
Country of origin United States Germany Australia Germany China Australia Indonesia/Japan Australia Australia United States China
Process Description Drycol Microwave Drying indirect contact drying in tubular dryers exothermic reaction. natural evaporation. accelerated drying at 25-30 °C fluidised bed stream drying High temp flue gas fluidised bed 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 pyrolytic process that employs heat and pressure in an oxygen free environment to continue the coalification process that occurs naturally in the earth
Drying Description Microwave Drying while keeping coal below 90 deg C drying achieved using low pressure steam of max. 180 °C, 4 bar drying achieved using low temperature waste heat to provide evaporative drying drying achieved using >100 °C low pressure steam drying achieved using >900 °C flue gas to dry 0–50 mm raw coal with 2-4% system O2 concentration under slight positive pressure 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 The process employs no additives and extracts both surface and inherent moisture.
Grade of heat used for drying Very Low Low Low Medium Low High Medium Medium High High Medium
Alternative uses for energy consumed in drying None power generation none power generation coal sales (fines used for combustion coal sales (fines used for combustion n/a electrical energy electrical energy electrical energy power generation
Pretreatment requirement Sizing for material handling crushing/screening (normal) (normal) plus mechanical mastication and extrusion (normal) crushing/screening to 50 mm (normal) crushing and mixing wit
CO2 exposures n/a n/a 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) Up to 25-35% CO2 reduction from the boiler 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 n/a
Waste streams generated from drying clean water none none none none none waste water stream none waste water stream waste water stream none
Byproduct streams possible none none demineralised water none none none n/a demineralised water none none tar product
Coal output stream description Direct use for briquetting/exporting or power generation coal pellets for use and export input coal for power generation only coal for sale or power generation 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 exportable coal for power generation
Coal output moisture level 10 - 30% 5-20% 12-14% 12-14% 6-30% 10-15% n/a 5-10% ~18% ~20% 1-15%
Coal output - transportable or exportable long-distance transport long-distance transport non-pyrophoric direct to boiler only short-distance transport non-pyrophoric non-pyrophoric non-pyrophoric pyrophoric pyrophoric hydrophobic, transportable & exportable
Industrial maturity Technology in food industry 35 years well established and proven technology, industrial plants of up to 3 MTPA capacity running in Germany and Czech Republic 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 It was used for coking drying since 1955 for over 200 wash plants one commercial scale plant, operations have not exceeded 30% of nameplate capacity pilot plant operational, demonstration plant 2008-2011 Pilot Plant 2002 - 2008, ready for commercialisation. Tested on Victorian and Indonesian coals pilot plant abandoned pilot plant operational 1MTPA plant in Inner Mongolia fully operational since 2012
  1. ^ ZEMAG Clean Energy Technology, Germany
  2. ^ Coldry Process, ECT Limited, Australia
  3. ^ RWE-WTE = RWE (Rhenish-Westphalian Electric) WTE technology
  4. ^ HTFG = Delta Drying Technology Ltd
  5. ^ WEC-BCB = White Energy Company, Binderless Coal Briquetting
  6. ^ UBC = Upgraded Brown Coal Process, Japan Coal Energy Center & Kobe Steel Ltd.
  7. ^ Exergen company, Continuous Hydrothermal Dewatering technology
  8. ^ MTE = Mechanical Thermal Expression, develop|ed by the CRC for Clean Power
  9. ^ KFuel = Koppelman Fuel, Evergreen Energy, Denver, Colorado, USA
  10. ^ LCP = LiMaxTM Coal Process Technology, developed by GB Clean Energy

History and advantages

United States

The best known producer of refined coal is a company based in Denver, Colorado called Evergreen Energy Inc. The company is publicly traded and is listed on the NYSE Arca exchange. According to the company's web site and its Form 10-K on file with the U.S. Securities and Exchange Commission, it was founded in 1984 with the goal of commercializing a coal-upgrading technology first developed in a Stanford University laboratory by Edward Koppelman. Taking the K from Koppelman's name, Evergreen, known formerly as KFx Inc., branded its refined coal product as "K-Fuel."

Much of the coal in the western United States is known as "lower-rank" coal that falls under the categories of "sub-bituminous" and "lignite" coals. These coals have high moisture levels and can be 20 to 30 percent water. This relatively high moisture content when compared to "higher rank" coals like bituminous and anthracite coals make lower-rank coals less efficient. The average heat content of sub-bituminous coal consumed in the United States is approximately 8,500 British thermal units (Btu) per pound. The K-Fuel(R) process uses heat and pressure to remove approximately 30 percent of the moisture from raw, low-rank coal and raises its thermal content to approximately 11,000 Btu per pound. [1] In addition to raising the coal's heat value, a significant amount, up to 70 percent, of the elemental mercury in the coal is removed and, because of its higher efficiency, lower chloride and nitrogen oxides emissions are achieved on a per kilowatt hour generated basis. [5]

The advantages of the refined coal process are more efficient transportation and the ability of utilities to switch to a fuel made of 100 percent refined coal or a blend of raw and refined coals in order to achieve lower emissions and greater efficiency. [6] A disadvantage is that the industry requires significant subsidies. An examination of government figures show that in 2007, for every megawatt-hour generated, refined coal received $29.81 in federal support, solar power received $24.34, wind power received $23.37, and nuclear power received $1.59. [7]

Australia

The producer of densified coal in Australia is a company based in Melbourne, Victoria called Environmental Clean Technologies Limited (ECT Limited) [8] The company is publicly traded and listed on the Australian Stock Exchange (ASX). The company was listed in 2005 with the primary purpose of commercialising the Coldry Process coal-upgrading methodology first developed in the Chemical Laboratory of Melbourne University by Dr B. A. John in the 1980s. The name of the process derived from the Calleja Group, which acquired the technology in 1994 and developed the technology to pilot demonstration at Maddingley Mine, Bacchus Marsh, Victoria in 2004 before licensing the technology to ECT Limited for further commercialisation in 2005.

The State of Victoria contains approximately 25% of the world's known reserves of brown coal (lignite). This coal is also amongst the world's 'wettest' coal, with a typical moisture content of 60 per cent water by weight. High moisture content makes Victorian brown coal an inefficient fuel source and is the primary reason why the Hazelwood power station in the Latrobe Valley is regarded as the world's dirtiest coal-fired power station. The Coldry Process uses low-pressure mechanical shear to create a natural exothermic reaction within the coal that then naturally expels 80 per cent of the moisture content. Expelled moisture is then captured and recovered as distilled water. Victorian brown coal transformed by the Coldry Process has a raised thermal content of 5874 kcal/kg, which is comparable to most export-grade Australian black coal.

The advantage of the Coldry Process is its ability to allow power generators to switch to a blend of raw as mined brown coal and Coldry pellets to achieve lower emissions in existing inefficient boilers, or achieve substantially less emissions by introducing black coal boilers and using 100 per cent Coldry refined coal pellets as a black coal equivalent. The Coldry Process provides the added advantage of creating new revenue streams for power generators through the production of a product that can be exported to other countries as a replacement for black coal. Unlike other refined coal processes, the Coldry Process is a commercial methodology that does not require subsidy.

Commercial development

United States

Evergreen Energy constructed a full-scale coal refinery near Gillette, Wyoming that began operation in late 2005. Designed originally to be a commercial plant, the facility encountered design and operational problems. Evergreen idled the facility in March 2008 [9] and instead used the plant as a process development platform with its engineering, construction and procurement contractor Bechtel Power Corporation.

Evergreen is now seeking to construct a coal refinery using the improved Bechtel design at locations in the Midwestern United States and in Asia. [10]

Australia

Calleja Group constructed a full-scale 16,000 tonne per annum pilot demonstration plant at JBD Business Park at Maddingley Mine near Bacchus Marsh, Victoria that began operation in early 2004. From 2005 ECT Limited upgraded the facility, added a water recovery process with Victorian Government funding in 2007 and operated the plant as a process development platform with its engineering partner ARUP. In 2009 ECT Limited secured and agreement with Thang Long Investment Company (Tincom) of Vietnam to finalise commercial feasibility ahead of construction of a 2 million tonne pa export plant by 2014 and 20 million tonne pa export by 2020. ECT Limited is using the ARUP improved design to secure technology licensing agreements with brown coal suppliers in China, India, Indonesia, Poland, Greece and Russia.

China

GBCE has built and is now operating the world's first industrial-scale coal-upgrading facility. It has capacity to process 1 MTPA of coal feedstock and is located in Holingol, Inner Mongolia, the largest lignite-producing region in China. [11] The coal is typically high moisture (35 – 40% TM) and 3200 – 3400 kcal gar. Depending on market requirements, it produces 5000–5500 kcal coal (gar) with greatly reduced moisture content (< 10% gar). The plant uses LCP coal-upgrading technology, which is a pyrolytic process that employs heat and pressure in an oxygen-free environment to continue the coalification process that occurs naturally in the earth. The processed coal by this technology is hydrophobic and transportable, which means it will not reabsorb moisture or break up into powder during transportation.

See also

References

  1. ^ a b [1] NextGen Energy Council Breakthrough Paper
  2. ^ [2] Pre Combustion Innovations Alliance
  3. ^ Reactivity and Reactions of Australian brown coals. R.B. Johns and A.G. Pandolfo Dept Organic Chemistry, University of Melbourne. 1980
  4. ^ "Archived copy". Archived from the original on 2015-06-28. Retrieved 2013-03-25. CS1 maint: discouraged parameter ( link) CS1 maint: archived copy as title ( link)
  5. ^ [3] Refined Coal Test Burn Results Black Hills Power
  6. ^ [4] Test Burn Results with Pennsylvania Utility
  7. ^ "Federal Financial Interventions and Subsidies in Energy Markets in 2007" (PDF). Energy Information Administration. CS1 maint: discouraged parameter ( link)
  8. ^ Environmental Clean Technologies Limited
  9. ^ [5] Evergreen Letter to Shareholders March 2008
  10. ^ [6] Evergreen Letter to Shareholders November 2008
  11. ^ http://www.gbce.com/en/projects_yield.php