(660c) Reengineered Feedstocks for Coal Combustion Emissions Control

Coal combustion is an important process for
electricity production in the United States. However, coal power plants
produce gases such as SO_x, NO_x and HCl, which can lead to
environmental problems including formation of acid rain.  Increasingly strict
regulations, such as the Clean Air Act, mandate the reduction of emissions from
coal combustion facilities. Currently, the U.S. produces ~7 quadrillion BTUs of electrical power per
year from coal, constituting 42% of all electrical energy being produced in the
country (in 2011).[1]  A number of
processes exist for cleaning these emissions to lower levels (e.g. wet
scrubbing the exhaust gas), but the augmentation of new chemical processing
equipment to existing power plant systems will introduce significant costs,
greater water consumption, and decreased energy efficiency.  A transformational
idea is to develop an energy-rich coal co-reactant from post-recycled materials
which can be utilized in existing coal combustion facilities as both a fuel
substitute and a sorbent of harmful process emissions.

A new coal-reaction technology
called ReEngineered Feedstock^TM (ReEF) has been developed by
ReCommunity Inc.[2, 3]  ReEF is
designed to be physically and chemically compatible to the coal that the coal
fired boiler utilizes, and can be directly co-reacted with coal with fuel
feeding and handling infrastructure in existing coal combustion systems. In
energy basis, it can replace up to 30% of coal with post recycling materials,
which otherwise would be landfilled, in existing pulverized coal combustion
facilities. The ReEF combines post recycling fiber products and plastics from
local residential and commercial municipal solid waste that are impregnated
with sorbents or chemical additives forming a Re-engineered fuel which can
serve to trap emissions such as SO_x.  The ReEF co-reactant and
emission reduction technology will be demonstrated on a laboratory scale using
a fluidized bed combustor (FBC) system[4-7].  Although the
addition of sorbents such as limestone, bauxite, kaolinite and CaO to furnaces,
to control the emission of toxic trace elements from coal combustion, have been
previously reported in laboratory, pilot or commercial scale fluid bed
combustors [5], the effectiveness
of these technologies has been proven limited and thus had little commercial
success. This study will be undertaken to demonstrate the effectiveness of the
ReEF as an innovative and efficient reactant co-feed for coal combustion and
emission reduction.  Optimization of combustor temperature, feed rate, fluidization
velocity and air to feed ratio will be determined for this system.  This
technology has the potential to significantly impact the economics and environmental
impact of both waste management and coal fired power plants.

References

1.             Refer to website http://www.eia.gov
2012.

2.             Bohlig, J.; Bai, D. Engineered Fuel
Feed Stock. U. S. Patent No. 8,157,874.

3.             Bohlig, J.; Bai, D. Engineered Fuel
Feed Stock. U. S. Patent No. 8,157,875.

4.             Stenger Jr., H. G.; Meyer, E. C.,
Laboratory-Scale Coal Combustor for Flue Gas Emission Studies. Energy &
Fuels 1992, 6, 277-286.

5.             Cheng, J. F.; H. C. Zeng; Z. H. Zhang; Xu,
M. H., The effects of solid absorbents on the emission of trace elements, SO₂
and NO_x during coal combustion. Int. J. Energy Res. 2001, 25,
1043-1052.

6.             Cao, Y.; Hongchang Zhou; Junjie Fan; Houying
Zhao; Tuo Zhou; Pauline Hack; Chia-Chun Chan; Jian-Chang Liou; Pan, W., Mercury
Emissions during Cofiring of Sub-bituminous Coal and Biomass (Chicken Waste,
Wood, Coffee Residue, and Tobacco Stalk) in a Laboratory-Scale Fluidized Bed
Combustor. Environ. Sci. Technol. 2008, 42, 9378?9384.

7.             Li, S.; Shuang Deng; Andy Wu; Pan,
W.-P., Impact of the Addition of Chicken Litter on Mercury Speciation and
Emissions from Coal Combustion in a Laboratory-Scale Fluidized Bed Combustor.
Energy & Fuels 2008, 22, 2236?2240.