Fossil Fuel-fired Power Plants can be a Positive rather than A Negative
Contributor to Water Quality
Operators of coal-fired power plants and gas turbine combined cycle power plants
can utilize municipal wastewater for cooling and other needs. When they also
eliminate discharges through zero liquid discharge (ZLD) technology they become
positive rather than negative contributors to water quality. Water lost through
evaporation can be greatly reduced by heat extraction from the flue gas before
it reaches the scrubber. This also reduces total CO2/MW and
makes the plant greener in every sense.
The markets and technology for this approach will be discussed in a free webinar
on February 25th at 10:00 a.m. CST.
The various geographical markets will be analyzed. China is embracing ZLD in
its power plants as well as its coal-to-chemical facilities. Gas turbine
combined cycle power plant developers in the U.S. are selecting ZLD not only in
arid areas but generally to avoid the need to obtain water discharge permits.
ZLD is the preferred option in Saudi Arabia and surrounding countries.
The availability and cost of treated municipal wastewater will be reviewed. In
general, power plants are near enough to municipal treatment plants to make the
use practical.
Technologies to minimize evaporation losses will also be discussed. The
potential is being increased by new developments such as catalytic filtration at
850oF.
China is making the largest investment in ZLD. Huaneng Group, China’s largest
power producer, has constructed a 1.3 GW state-of-the-art ultra-supercritical
coal-fired power plant at the Changxing Power Station in Zhejiang Province.
Aquatech has supplied ZLD systems for a number of power plants and
coal-to-chemicals plants. Enel has purchased several systems from Aquatech for
its Italian coal-fired power plants. Aquatech has a Zero Liquid Discharge (ZLD)
plant in a coal-to-chemicals facility in Inner Mongolia. The ZLD plant
incorporates HERO™ (High Efficiency Reverse Osmosis) and a Thermal
Brine Concentrator. The plant will treat 2400 m3/day of wastewater
and reuse 92.5 percent of it, producing 2000 m3/day of process water
and 220 m3/day of distilled water for various end user applications.
China has some ZLD systems using evaporators but is leaning toward the cheaper
route of using flue gas to evaporate liquid in the sludge. The spray drier
approach is being offered by Mitsubishi, URS and other international companies.
The various approaches for evaporation of water from slurries will be analyzed.
One option is a falling film evaporator (inside the brine concentrator vessel)
that is seeded with calcium sulfate to minimize scale formation.
Mechanical
vapor recompression (MVR) is the method by which a blower, compressor or jet
ejector is used to compress, and thus, increase the temperature of the vapor
produced. In this way, the vapor can serve as the heating medium for the ZLD
solution being concentrated. The efficiency and feasibility of this process lies
in the efficiency of the blower or compressor and the heat transfer co-efficient
attained in the heat exchanger contacting the condensing vapor and the
boiling ZLD liquid. Several different blower and compressor options will be
reviewed.
The discussion will also include the co-combustion of sewage sludge and the use
of gasified sludges as reburn fuels in coal-fired boilers.
A full review of the options for coal-fired power plants is provided in 44I
Power Plant Air Quality Decisions.
A full review of options for gas turbines is part of
Gas Turbine
and Combined Cycle Decisions. Both of these services are free of
charge to power plants and by subscription for others.
Utility E-Alert Tracks Billions of Dollars of New Coal-fired Power Plants on a
Weekly Basis
#1259 – February 12, 2016
Here are some headlines from the Utility
E-Alert.
UTILITY E-ALERT
COAL - US
COAL - WORLD
The
41F Utility
E-Alert
is issued weekly and covers the coal-fired projects, regulations and other
information important to the suppliers. It is $950/yr. but is included in the
$3020
42EI
Utility Tracking System
which has data on every plant and project plus networking directories and many
other features.
Bob McIlvaine
President
847-784-0012 ext. 112
rmcilvaine@mcilvainecompany.com
www.mcilvainecompany.com