Working with Specific Customers and FGD & DeNOx Decisions- Pacific
Corp
44I Power Plant Air Quality Decisions
is a guide which is supplied free of charge to any power plant. Pacific Corp is
one of the users and is currently facing major expenditures which may be
mitigated by using catalytic bags, SNCR, Lotox. Catalytic air heater baskets or
other options.. McIlvaine will be looking for input from anyone and also
working closely with supplier subscribers to compile some options over the next
month and then schedule a webinar with Pacific Corp personnel and the supplier
participants to discuss the various alternatives.
EPA is issuing a federal plan that will require the installation of emission
control technologies and reduce NOx emissions from four electrical
generating units at PacifiCorp's Hunter and Huntington power
plants in Emery County, Utah by 9,885 tons each year. The Agency is also
approving portions of the state's plan addressing particulate matter emissions
at these plants.
Supplier participants with the Utility Tracking system should first review the
data for each plant which is easily displayed just be using the plant name
search. Here are extracts on one plant:
plant name:
Huntington
epa unit id: 1
new owner: Scottish Power, sold to MidAmerican Energy
Holding
parent utility: MidAmerican Energy Holding
utility name: PacifiCorp
state: UT
county: Emery
size MW: 446.4
future plans:
plant startup: 1977
fuel specific: Bituminous
alternate fuel: none
boiler type: Pulverized Coal Dry Bottom
boiler manufacturer: ABB Combustion Engineering
part addition: baghouse
part addition startup: 2010
part addition supplier: Hamon Research Cottrell (Casey Industrial)
part addition architect: Stanley Consultants
part air flow ft3 min: 1700000
NOx Low NOx burners
NOx emissions have dropped from over 8000 tpy in 2008 to 3500 tons by
2012
FGD:
FGD startup: 1978 FGD supplier: GE Env. Services, Chemico
FGD architect
FGD changes to original
FGD reagent: lime
FGD process: wet
FGD survivor company: Marsulex
To learn more about this specific project and the program contact Bob McIlvaine
at
rmcilvaine@mcilvainecompany.com
847-784-0012 ext. 112
HOT TOPIC HOUR
FGD and Heat Recovery Hot Topic Hour on June 16 reveals Unique Opportunities for
Power Plants
New Structure with Free Decision Guides for Power Plants around the World
The Hot Topic Hour held on the June 16 was focused on the removal of SO2
and SO3 from power plant stacks but also provided lots of innovative
ways to make power plants more efficient by sorbent injection and heat recovery.
More importantly it demonstrated that there are new paths for power plants to
gather the key information for decision making and for suppliers to communicate
with the power plants in a way where the lowest total cost of ownership can be
determined for the product in question.
The challenge is to convince the decision maker in Vietnam that the higher
efficiency blower will reduce electricity costs and more than offset the initial
price or that the membrane bag will last enough longer to justify its higher
price. There are three elements to success in this quest:
Free decision systems for power plants provide the route for vendors to make
their case. McIlvaine is providing free access to recorded webinars and to
certain publications for end users around the world. They are also reached with
a bi-weekly Alert and 4 weekly newsletters. The supplier can best leverage this
opportunity by making sure their information is displayed.
The end users have free access to the following publications:
Dry Scrubbing is extensively covered in the decision systems.
There is a subsidiary website in Power Plant Air Quality Decisions
focused just on dry scrubbing. It addresses questions such as
One of the decisions is the type of dry scrubber that is best. Originally SDA
was the main option. Now CDS is popular. DSI with the more reactive sorbents has
become an option even when higher efficiency is required.
The catalytic filter with DSI promises one stop shopping. Combinations such as
DSI and SDA are also an option.
FSI + Catalytic Filtration + Condensing Heat
Exchangers (CHX) - How to make Pollution Control Profitable by Martin Schroter,
Dürr Systems - Hot Topic Hour March 19, 2015.
The dry scrubber is necessarily part of a multi pollutant removal system that
addresses particulate, acid gases and toxic metals. As a result, evaluation of
the impact of the dry scrubber on the removal of pollutants such as mercury is
important. The changing regulations in the U.S., China and the EU all need to be
addressed.
Solid waste is an issue. Can the sorbent/acid/ash combination be used as
construction materials? What about leaching of toxic metals? The
loss of flyash and gypsum revenues need to be evaluated. The benefits of lower
water use and elimination of wastewater are also important.
There are many process factors. One is the sulfur content of the fuel versus the
required efficiency. Another is the temperature of the air leaving the heat
exchanger and the potential for DSI ahead of the air heater to allow greater
heat recovery.
LIFO vs. FIFO for SO2 capture
The recent regulation of many pollutants combined with new technology, which
makes it possible to remove all the pollutants in one device, has greatly
increased the use of fabric filters. However, there has not been a recognition
of what McIlvaine describes as "The importance of FIFO vs. LIFO in Dust Cake
creation."
Direct sorbent injection (DSI) and embedded catalyst dictate a new approach to
bag cleaning. In addition to discrete particle capture, bag filters are
being tasked with:
The importance of the method of bag cleaning can be illustrated by use of the
accounting approach to inventory. Two options are first in first out (FIFO) and
last in first out (LIFO). If the price paid stays the same, the choice between
the two accounting methods makes no difference. But, if the cost of recent
inventory is greatly different than the past, then the accounting method makes a
big impact on profits.
The capture of discrete particles is the equivalent of price parity. Let's say
that when you pulse a bag you are always discharging the latest particles to
arrive and the remaining cake consists of the earliest. Since the ability of a
matrix of dust particles to act as a filtration medium does not change, it does
not matter which particles remain. In fact, maintaining a somewhat permanent
layer of cake protects the fabric from wear. Also a more permanent cake provides
higher dust capture. It has been shown that on-line cleaning results in some
re-deposit of dust particles. But this is does not impact discrete particle
capture efficiency.
The new paradigm with DSI is a big price difference. The newly arrived lime
particle has the capability to absorb acid gases. The lime particle deposited
earlier is already converted to calcium sulfate and provides no additional
absorption capability. The semi-permanent cake layer is very undesirable for
acid gas capture. Mercury re-emission is also a risk for an activated carbon
cake which is semi-permanent. So it is very important to adopt FIFO and not
LIFO.
This leads to the obvious question as to which are the best cleaning methods to
achieve LIFO? The long running debate about surface filtration vs. depth
filtration needs to be reviewed in light of FIFO. Also, the pulsing method
itself needs to be reviewed. Do some methods result in more re-entrainment of
particles in the previous cake than do others? Should more of the cake be
removed with each pulsing?
It could be argued that the reaction takes place in the ductwork and not on the
bag. But the big difference in performance of bag filters vs.
precipitators with DSI proves that the cake absorption is substantial.
There may be lots of research on this subject but if so, McIlvaine would
appreciate feedback on it. If there is not, it is an area deserving lots
of attention.
Bag cleaning is also made more challenging by the increasing use of ceramic
filter elements. The advantage of these elements is the ability to remove dust
at 850°F. The older generation rigid ceramic has been replaced by ceramic fiber
media which can be pulsed. However, this media cannot necessarily be pulsed with
the identical system used for synthetic bags. An alumina refinery in Australia
was having cleaning problems with a ceramic filter. Pentair-Goyen
analyzed the situation and provided a more robust pulsing system. This solved
the problem.
Ceramic, glass and even synthetic media are incorporating catalyst in the media
to reduce NOx or oxidize dioxins. Do these designs require a
different cleaning approach? The catalyst in the Clear Edge
design is not on the surface. So, the dust cake will not affect performance
except if it causes maldistribution of the gas. If more gas flows through one
area than another, the reactivity of the system is reduced.
A broader subject is the whole approach to cleaning. High pressure/low volume is
the most popular option. Does capture of these other pollutants open the door
for high volume /medium pressure or even for reverse air cleaning?
The potential for the one-stop shopping is great. Costs of pollution control can
be reduced for new installations. The small footprint makes a big difference in
the cost of upgrading existing plants to meet new air pollution rules. It is,
therefore, important to understand and then maximize FIFO potential.
We asked Pentair-Goyen to provide us with the parameters which they believed
would be important in fine tuning the bag cleaning to achieve FIFO. They
provided a listing in four segments.
A number of participants indicated that they believe this is an important
subject for investigation. Marty Dillon pointed out that the
retention of mercury on the dust cake is also an issue. Mercury re-emission is
more likely to occur with LIFO. McIlvaine is looking for additional input on
this subject. Pentair-Goyen indicated their willingness to participate and to
optimize cleaning for dust, acid gases and mercury.
Utility participating today wants to eliminate Sodium Sulfate Ponds
A utility participating in this discussion has contacted us and asked for our
recommendations on how to eliminate the sodium sulfate pond.
Two-Stage Scrubbing with Rare Earth, HCl, and Gypsum Byproducts
Two-stage wet scrubbing can be utilized to produce rare earths, 30 percent
hydrochloric acid and gypsum. DOE has just awarded 10 grants to
pursue rare earth extraction from flyash. Previous studies have shown that rare
earths can be economically extracted from a number of types of coal flyash. The
processes investigated by both DOE and the Chinese government are based on
digging up flyash from landfills and going through the expensive size reduction
processes. Acid leaching is then employed.
The two-stage scrubbing process would eliminate much of the expense. The flyash
and HCl are captured in the first scrubber while the SO2 is captured
in the second. A WESP is needed for final particulate cleanup because the dust
load leaving the first scrubber will be around 0.l lbs/MMBtu.
By recycling the scrubbing liquor in the first stage and maintaining a pH of 1
by a controlled bleed stream a dirty 30 percent hydrochloric acid stream is
maintained. The dirty acid is then already in a condition for leaching of the
rare earths. McIlvaine was President of Environeering when it
teamed with United Engineers to provide two-stage scrubbers at
Philadelphia Electric. A number of waste incineration
facilities in Europe are making hydrochloric acid and recovering the metals. So
the technologies are well established.
When McIlvaine initially published the information on the two-stage scrubbing
approach there was immediate interest and inquiries from DOE. But subsequently
nothing transpired.
Improving Plant efficiency by capturing Waste Heat will go a Long Way to meeting
Future Regulations
Benefits of combining Sorbent Injection and expansion of the Air Preheater
Arvos
and AECOM have teamed to combine air heater enlargement and
sorbent injection to substantially increase power plant efficiency. A 500
MW power plant in Indiana is successfully operating with sorbent injection to
reduce SO3 followed by a modified air heater and is achieving a 70
percent reduction in air preheater outlet temperature with no increased
maintenance.
Gus Shearer
of Arvos was optimistic about the size of the potential market for this
technology. There was some discussion of the Chinese market and the need to
reduce precipitator emissions. Some plants are installing WESPs but the air
heater upgrade would be much more economical. The Chinese are even more
concerned about air heater performance than most countries. Whereas most
operators are content with 6 percentage in-leakage to the air preheater, the
Chinese are striving for only 3 percent, according to Gus.
The reduction in precipitator emissions has been well documented by
Mitsubishi and Hitachi. Close to 10,000 MW of
Japanese coal-fired capacity uses heat exchangers which reduce the inlet
precipitator temperature to 195°F. At the lower temperature the
precipitator that was emitting 25 mg/Nm3 of dust is now emitting 10
mg/Nm3.
Howden has the Package including Air Preheater, Fans, and Blowers (conveying
Lime)
·
Howden Group
has extensive international experience in the manufacture, turnkey installation
and operating characteristics of heavy duty fans, rotary air preheaters and Gas
Gas Heaters - with present major markets being in China and the Far East.
Their activities have focused on emission reduction systems by reducing the
leakage levels and improving the availability and thermal efficiency of these
rotary heaters.
Various coal-fired plants have benefitted from using Howden's VN sealing
retrofits, special element designs and on-line HP washing of the element
baskets.
While these maximize availability and maintain plant performance over time,
thereby reducing the need for DSI, such modifications are complementary to
sorbent injection when targeting reduced flue gas temperatures and mercury
emissions.
Howden's acquisition of Roots Blowers in 2015 brings further product
capability within the power sector for the pneumatic conveying of DSI.
End users have significantly reduced their operating cost and increased revenue
by optimizing the combination of heater elements, on-line HP washing and APH
sealing and draft fan upgrades.
Reductions in gas volume flow associated with sealing retrofits and reduction in
gas outlet temperature significantly improve the performance of both ESPs and
FGD plants while minimizing fan power.
When considering additional plant items, optimization may be constrained by the
plant
layout.
Integrated plant solutions achieve emission reductions with reduced unit heat
rate and provide extended plant life.
Anqing heats Boiler Feedwater
Shenhua Shenwan Energy Company's
Anqing Power Plant Phase II's 2×1000-MW expansion project includes many energy
saving features.
An approach to saving energy was capturing the waste
heat in the flue gas and using it to preheat the boiler feedwater. Operating at
the designed full load, the flue gas heat exchanger recovers 44,000 kW of heat,
which reduced heat consumption by 45 kJ/kWh, and reduced the plants' standard
coal consumption by 1.65 g/kWh.
Co-locating Municipal Wastewater Treatment Plants and Power Plants
Municipal sludge and treated wastewater are already being used by power plants.
Sewer mining means taking what flows nearest the plant and treating it in the
power plant
Benefits:
Can heating the Draw Solution in a Forward Osmosis ZLD System be a Beneficial
Waste Heat Use?
Forward Osmosis (FO) holds lots of promise for many applications. Whether FO
should be considered for any specific project will depend on:
·
Application specific details such as the solids content of the slurry and the
availability of waste heat.
·
Approaches to regenerating the draw solution.
·
Process design and integration with RO and other sub-processes.
·
Membrane quality
·
Product quality considerations.
There has been considerable effort to apply FO in direct competition to RO. To
date, most of the success has come where FO has unique performance advantages
such as use with high solids wastewater in power plant FGD systems and frac
flow-back. Food applications where FO uniquely impacts product quality are also
examples.
Oasys Water
is transforming high salinity wastewater at the Changxing Power Plant. Oasys
Water and its Chinese partner were selected to deliver the world's first
commercial application of Forward Osmosis (FO)-based ZLD at the state-of-the-art
Changxing coal-fired power plant. Oasys provided its ClearFlo MBC system and
pre-concentrating reverse osmosis (RO), while Beijing Woteer
supplied physic-chemical filtration, ClearFlo Complete ion exchange
pretreatment, and a crystallizer package.
In the FO Decision Guide we want to explore ways which energy for the FO can be
supplied with waste heat from the power plant.
What about using a direct gas-to-liquid heat exchanger in the exhaust stack and
pump the draw solution through this exchanger? It would reduce flue gas
temperature as well as provide the FO energy.
What about using water in the exchanger and add MVR to bring it up to the right
temperature?
Should Ethanol or Other Co-generation Candidates be Co-located at Power Plants?
Should operators of older plants consider converting their facilities into a
manufacturing complex rather than shutting them down?
Should Recirculating Aquaculture Systems be Co-located at Power Plants?
Power plants can only reach 50/60 percent production efficiency, which results
in a great deal of energy wasted in the form of heat.
Past research and aquaculture facilities tried to harness the waste heat of the
cooling waters of power plants without much success.
The main cause of failure of these type of aquaculture systems was due to
unregulated discharges of pollutants in the cooling waters or unplanned shut
down of the plant resulting in sudden lack of heated water.
Modern technology is approaching the concept of using waste heat through the use
of heat exchangers.
The use of waste heat in Recirculating Aquaculture Systems (RAS) for the culture
of warm water species such as tilapia, perch, turbot, seabass, and eel could
decrease running costs and increase the profitability of the venture.
Harnessing of waste heat decreases environmental impact of power plants and
reduces the energy need of RAS facilities.
Waste heat might be successfully coupled with integrated aquaculture to achieve
an environmentally, socially and financially sustainable enterprise.
This question is being addressed by a partnership between the Loughs
Agency, Queen's University Belfast, and the
University of Glasgow, supported by the EU's INTERREG IVA Program,
managed by the Special EU Programs Body (SEUPB).
Air Conditioning and maybe even Ice from Power Plants
It appears that justifying the heat recovery is easy in the winter in cold
climates but what about Indonesia, Vietnam and India where it is hot most of the
year?
Co-generation with air conditioning would be one answer.
But what about areas that do not even have enough electricity to run air
conditioners and are too distant to consider district cooling? Why not generate
ice and deliver it by truck? This is the way much of the U.S. dealt with
the heat a century ago.
Many deaths in India recently were attributed to the extreme heat. So there is a
lifesaving potential to this approach. Water is already being delivered by
truck, why not ice?
Gus Shearer
of Arvos volunteered that he had seen applications for air conditioning in India
and will search for the background information to send to us.
Co-location of Greenhouse Farming is a likely Winner