MEMORANDUM

From: The Office of Air Qu ality Planning and Standards U.S. Environmental Protection Agency

To: EGU NSPS Docket (EPA-HQ-OAR-2013-0603)

Date: June 2014

Subject: Coal Cleaning and Upgrading

Introduction

Low-rank coals (lignite and subbituminous) are often us ed because the low cost per unit of heat input
relative to bituminous coal and the low sulfur content. However, a ma jor disadvantage of low-rank coals is their high moisture content, typically 25 to 40%. When this coal is burned, considerable energy is required to vaporize and heat the moisture, thus reduc ing the efficiency of the EGU. As fuel moisture decreases, the heating value of the fuel increases so that less coal needs to be fired to produce the same amount of electric power. Drier coal is also easier to handle, convey, and pulverize – reducing the burden on the coal-handling system. In addition, an EGU boiler (and th e corresponding control equipment) designed for dried coal is smaller an d has lower capital costs than a comparable EGU designed to burn coal that has not been dried. The pre-combustion dr ying of low-rank coals can improve the overall efficiency and several advanced coal drying technologies are available.

Coal upgrading is a term used to describe processes th at reduce the moisture cont ent of the coal and that create a stable product that avoids spontaneous combustion and moistu re reabsorption. The final product from these coal upgrading processes have a higher heating value and generally emit less pollutants. The following is a brief summary of some of the coal upgrading technologies , including propriety technologies. This summary is not intended to be a comprehensive list of available technologies. The performance values given here are those that ha ve been provided by the technology provider in publically available sources. Inclus ion of a technology in this summary is not intended to be an endorsement of that technology by the US EPA or the US Government. Figure 1 shows the estimated heat rate impact of coal heating valu e as estimated by the National Coal Council 1 and the Integrated
Environmental Control Model. 2

Figure 1: Impact of Coal Quality on Heat Rate

1 National Coal Council, “Opportunities to Expedite the Construction of New Coal

‐ Based Power Plants,” (2004). Available at: http://www.nationalcoalcouncil.or g/Documents/Expe diteNov30rpg.pdf

. 2 Download available from: http://www.cmu.edu/epp/iecm/Coal Upgrading Technologies

Advanced Coal Conversion Process

Rosebud SynCoal Partnership’s Advanced Coal Convers ion Process (ACCP) was one of the first largescale coal upgrading projects in the US. ACCP was co-sponsored by th e United States Department of Energy (DOE) Clean Coal Technology Demonstration Program (CCTP). The process consisted of two thermal reactors, one to evaporate water and the ot her to remove chemically bound water, and a third physical cleaning stage to cool and separate mine ral matter and SynCoal product. The demonstration facility operated for 9 years. Various coals were pr ocessed for a variety of customers. Records indicate the SynCoal was able to improve boiler efficiency at some power plants by 1-4%, along with reductions
in NO X , ash, and sulfur. While the SynCoal product quality was as expected, the pr oduct was not able to incorporate a cost-effective way to stop spontaneous combustion.

BCB technology

White Energy’s binderless coal briquetting (BCB) technology upgrades subbitu minous and lignite coals and coal fines through a thermal drying process follo wed by physical and chemical stabilization through a binderless briquetting process. Th e BCB process produces stable transp ortable briquettes with a lower
moisture content and corre sponding higher heating valu e than the original feed coal. White Energy has
constructed the Cessnock Demonstration and Producti on Plant in Australia allowing the company to demonstrate and test the process on potential clients’ fuel sources. In the future, White Energy plans to refine the process for bi tuminous fuel, as well.

Exergen Technology

Exergen’s Continuous Hydrothermal De-watering (C HTD) technology has been developed for lignite and high-moisture subbituminous coals. CHTD is a d ecarboxylation reaction with high heat and pressure followed by a separation process. The process has b een tested on a small pilot plant that has proven successful. The company has plans to build a demonstration plant, con tinue testing new fuel sources, and further research and development projects.

GEO-COAL

Total Sinergy International’s (TSI) GEO-COAL re moves moisture from lo w-rank coals, primarily lignite, via heat provided fr om gasifying the coal fines. The first st ep in the process crushes the coal. All coal fines are separated and sent to the gasification burners, while th e remaining coal continues to the drying area. The gasifiers provide super-heated steam to drive out th e moisture, then the product is cooled. The Indonesian company has a coal upgrading plant in Indonesia that has successfully tested the upgrade capabilities on many di fferent coals. They market three different coals, GEO-LITE, GEO-HI, and GEO-MET based on the product quality. TSI has si gned an agreement with the Indonesian national utility company to use GEO-COAL technology at thei r facility. They are mark eting their products to Asia, Australia, Indonesia and India.

GTLEnergy Technology

GTL Energy has developed a technology to upgrade lo w rank coals and biomass. The process is a low temperature process that removes moisture content. The resultant product is a co al briquette. In the case of their biomass and coal test, the result was a wood a nd coal mix briquette. The product has been tested on different coals from around the world. The compa ny has a demonstration plant in North Dakota and has just completed constructi on on a plant in New Zealand.

K-Fuel®

Evergreen Energy’s K-Fuel® process removes moistu re and mercury from th e coal through heat and pressurization of low rank coals ( lignite and subbituminous). The fi nal product (K-Fuel®) has a higher heating value, lower mercury content, is physically and chemically stable, and can be handled andtransported similar to untreated coal. A commercial plant and testing lab in Gillette, Wyoming have processed and tested a variety of low rank fuels from different countries. A few power plants have been host to test burns of the K-Fuel® product to valida te the combustion benefits . The company’s latest announcements indicate pursuing investors and clients in Asia and Australia.

Mechanical Thermal Expression

Mechanical Thermal Expression (MTE) is a process in wh ich a coal water slurry is created, then fed into a reactor that applies mechanical pressure. The pressu re is believed to decrease the pore sizes in the coal and also lower the density of the water, so the coal holds less mass. The coal is then dewatered before being fed into the boiler. MTE has been tested in the lab on various coals from Indonesia, Australia, Germany and India.

PristineTM

Clean Coal Energy Inc.’s PristineTM is a continuous process where coal is heated gradually in an inert atmosphere, using a set of multi-state heating cham bers. The patented multi-stage treatment process removes moisture, volatile materials, and contam inants, including organic sulfur, mercury, and facilitates the removal of ash. Subbituminous, lignite a nd metallurgical coal have been tested and proven under this process. The volatile ch emicals emanating from coal are recovered for useful purposes. The methane is returned to the proce ss and used for heating the incomi ng coal. The light hydrocarbons can
be used as a fuel source or sold to refiners to be blended with crude oil and refined to produce transportation fuels and chemicals. The heavy gase s are condensed onto the coal surface and seal the openings to limit the ability of th e coal to re-absorb moisture or combust spontaneously. The end product (PristineTM) maintains the stru ctural integrity of the original coals and is sufficiently rigid to withstand the rigors of coal handling and transport, yet requires reduced energy for pulverization at the power plant just before combusti on. As advancements have been ma de, Clean Coal Energy Inc. has evolved another product, Pristine -MTM, to address problems with their first generation product. Construction for a test plant in Oklahoma began as an effort by SAIC and Clean Coal Energy Inc. They have been successful in showing efficiency im provements in the testing of over 40 coals.

Rinker

‐ England-Skov (RES) coal conversion process

ConvertCoal, Inc. (CCI) pr oprietary coal-to-liquids process convert subbituminous and lignite low-rank coals into synthetic crude oil and increasing the hea ting value of the feed coal by approximately 40%. In the process, the feed coal is milled to 1⁄4 x 1⁄2-inch, then dried and pyrolyzed at about 1,000°F to recover approximately half of the volatile matter as coal-tar oil. The CCI process typically removes
two-thirds or more of the sulfur and the majority of the volatile merc ury and water from the feed coal.
The CCI Process converts each ton of low-rank coal in to approximately 0.8 barrels of synthetic crude oil refinery feedstock, 0.5 tons of upgraded coal, and 0.3 tons of water.

Upgraded Brown Coal

Kobelco’s Upgraded Brown Coal (UBC) process involve s crushing the coal in a grinding mill. Then, the coal is mixed with light oil and a heavy oil, before being dewatered. Heat and pressure are applied that generates a process vapor containing water and the oil. The next step is a centrifuge to separate the slurry cake from any remaining oil before the coal product is briquetted and the oil is recovered for reuse. The facility has constructed a demonstration plant that has prove n the technical a pproach to their process on lignite coal. The product is stable so that is can be easily transporte d. They are still in the steps of testing the final UBC product.

Zemag

The German company ZEMAG Clean Energy Technol ogy GmbH has been marketing and implementing their Zemag process to upgrade lo w rank lignite coal. The process sc reens and pulverizes lignite coal
before it is sent to the tubular dr yers. In the inclined dryers, the product flows down, while low-pressuresteam surrounds the tubes for the heat transfer. Following th is step, the coal is sent to a press where it is briquetted. This process is used in being used at plants in China and Germany. It is an established process that provides a stable product.

Coal Drying Technologies

Densification

The general densification process takes run-of mine brown coal and mills it to approximately 50 mm lumps. These lumps are fed into a low intensity sh earing attritioning mill which reduces the particle size to approximately 10 μ m. This reduction in particle size releases the water that has been trapped within the porous structure of the raw coal. Th e plastic attritioned coal is extrud ed into pellets or blocks and the moist product is conveyed for drying by evaporative loss of water to the atmosphere. Several companies have developed variations on this process:

Environmental Clean Technologies Ltd. has commercialized the COLD RY process, which uses an
exothermic chemical reaction in combination with wast e heat from a co-located power station to dry and pelletize brown coal. The final product is stable and can be transpor ted safely. This process can be applied to lignite and subbituminous coal.

Jott Engineering has developed the Jott Solid Fuel Dryer System (JDS), which uses low-grade waste energy from the cooling water system at the power plant to dry the plant' s solid fuel. This process can be used to dry brown coals during the pe lletizing process, but is also applic able to other fuel types such as biomass solids. The company has ac quired patents for the process.

Pacific Edge Holdings in Austraila has invested in coal drying efforts via La Trobe Lignite Development. They have patented a combination of mechanical, thermal and chemical processes that can be applied to brown coal for drying before producing a pellet or br iquette. The outputs are hydrocarbon gases, water and metall urgical coke equivalent. The comp any focuses on creating these dry fuels from lignite for use as metallurgical coals.

Drycol

DBAGlobal Australia Pty, Ltd. is de veloping a coal drying technology wi th the trade name Drycol. The process uses the controlled applicati on of microwave radiation to dry all coal types. Coal feed stock is first separated into fine grade co al and one or more larger grades . The fine coal is loaded onto a conveyor and conveyed continuously through a microw ave-energized heating ch amber for drying. The fine grade coal is dried sufficiently so that when it is recombined with the larger grade coals, the moisture content of the aggregate coal is within a target moisture content range. Microwave energy is effective for drying coal because water that is contained with and within the coal is preferentially heated rather than heating the coal. Corre spondingly the heating rate of coal is much less and linked to heat
transfer via conduction from water molecules. Provi ded that the residence time of the coal in the microwave applicator chamber is controlled such that the coal temperature remains less than 90°C, there is no opportunity for short chain hydrocarbons to vol atilize from the coal matrix, and therefore coal quality does not degrade. A steel plant in Kentucky hosted a commer cial scale test of the product showing Drycol’s capability.

DryFining TM

Great River Energy’s DryFiningTM pro cess has been developed at the Co al Creek Station plant, a mine mouth lignite-fired plant. The DryFiningTM process passes warm cooling water from the steam turbine exhaust condenser through an air heater where ambient air is heated before bei ng sent to a fluidized bed coal dryer. The dried coal leaving the fluidized bed is sent to a pulve rizer and then to the boiler. Air leaving the fluidized bed is filtered befo re being vented to the atmosphere.

In addition to using power plant waste heat to redu ce moisture, DryFiningTM also segregates particles by density. This means a significant amount of higher density compounds containing sulfur and mercurycan be sorted out and returned to the mine rather than utilized in the boiler. Net gains in overall efficiency of 2 to 4% are reported for the process with th e lignite heating value increases from 6,200 to 7,100 Btu/lb. The process has been proven on lignite coal, and the owners ar e now marketing their process within the US and domestically. They also recommend the process for subbituminous fuels.

MicroCoal®

MicroCoal® Technologies has creat ed MicroCoal® to upgrade lignite . By implementing a microwave technology, the original brown coal has reduced moisture and a hi gher energy value. The facility conducted tests and are confident in their produ ct. They have begun cons truction on commercial
facilities in Indonesia and are disc ussing other commercial projects.

WTA

RWE Power in Germany is developing a steam fluidi zed bed drying technology for lignite called WTA. A fundamental difference compared to the DryFiningTM process is that the WTA process first mills then dries the lignite while the DryFiningTM pr ocess first dries then mills the lignite

. For the WTA process, lignite is first milled to a fine particle size by hamme r mills in direct series with a two-stage fluidizedbed dryer. The dried fuel exiting the stationary be d is separated from the gas stream and mixed with coarser lignite solids collected from the bottom of th e dryer bed and then fed di rectly to the boiler. The heat needed for the drying of the fuel is supplied by external steam, which is normally taken from the
turbine with the heat transfer taking place in tube bundles located inside the bed. Based on the development work completed to date of the WTA technology, the net gain in cycle efficiency is reported to be on the order of 4 percentage points, depending on the moisture content of the raw coal and the final moisture of the dried lignite.

Other Technologies

Other coal drying/upgrading techno logies for low-rank coals includ e: 1) NOAIR and CANONA flash heat drying from Green Global T echnologies Ltd, 2) high velocity air flow/grinding (e.g., DXCoal’s DevourX machine, LF Pumping’s LamiFlo TM Drying System), 3) hydrotherm al dewatering (wet coal is heated under pressure to over 250°C and the coal structure breaks dow n and shrinks, releasing the water as a liquid; e.g., Ignite Energy Resources), 4) heating coarse crushed coal under pressure to approximately 200°C (e.g., Aquex), and 5) superh eated steam drying (e.g., Pinches Consolidated Industries; GEA Process Engineering), and 6) microbial hydrolysis (e.g., Terra Genesis).