Addendum - November 1, 2019
True Costs of Power Plant Flow and Treat
Products will be discussed at
Power-Gen but also as a Continuing Process
McIlvaine is preparing tour guides relative to
various flow and treat products at PowerGen in
New Orleans, November 18-21. These
are displayed at http://www.mcilvainecompany.com/PowerGen_2019/Power-Gen_2019_Information.pdf
This is part of a Silobuster Program to penetrate geographic, corporate, and technology silos. So, the guides will be equally useful at PowerGen India, PowerGen Asia, or PowerGen Europe. The segment relative to gas turbine inlet filter media will be utilized at a major filtration conference sponsored by the world’s largest non-woven media association. The silobuster programs are listed at http://home.mcilvainecompany.com/#. You see among others one on coal-fired boiler flow and treat http://home.mcilvainecompany.com/index.php/silobusters/44i-coal-fired-power-plant-decisions and another on gas turbine flow and treat http://home.mcilvainecompany.com/index.php/silobusters/59d-gas-turbine-and-reciprocating-engine-decisions
The purpose is to create access to the important silos of information which allow a purchaser to determine the true cost of a product or service. For a supplier with the lowest true cost product it is a whole new route to market www.mcilvainecompany.com Most Profitable Market Program.
Who funds these programs? Since the services are available free of charge to purchasers, the suppliers are the funders. Investments which would otherwise have gone to “sales leads” can be cost effectively diverted. Advertising can be coordinated so that it helps to validate a true cost claim. For example, when you click on the Power Engineering background article on HRSG corrosion control you also see an advertisement for Magnetrol level and flow control. This is an archive from February, so Magnetrol is obtaining long term benefit from its advertisement.
The tour guides are designed to assist in purchasing related decisions. The decision makers are the people most sought after by suppliers. By providing networking with email and cell phone contacts of those interested in making purchasing decisions rather than just gaining background knowledge, the value of exhibiting is increased.
The value in supporting these silobuster initiatives is already being realized by some of the media and it is expected that others will follow. The McIlvaine Company charges suppliers modest fees to be involved in a silobuster program and counts on revenues from helping these companies pursue this new route to market for which individual purchase forecasts are the foundation.
Background documents relative to tour guide
subjects have been published. Here
are the ones published in this Alert over the
last two weeks.
True Cost of Limestone FGD Recycle Pumps
Woven Belts and Cloths for Coal Fired Power
Plants
Here is background
on additional subjects.
True Cost of Gas Turbine Inlet Filters
The McIlvaine Company is working with
associations, media and suppliers to create true
cost analyses of combust, flow and treat
products and services. One such initiative is
the “True Cost of Gas
Turbine Inlet Filters.”
The true cost of a gas turbine inlet filter can
be affected by a large number of factors. These
factors are not constants but are changing. The
filter purchaser is challenged to not only
identify these factors but to keep up with the
changes.
Large gas turbines are used to generate
electricity by utilities. Smaller gas turbines,
drive pumps and compressors in locations with
extreme conditions such as desert dust, artic
snow or sea spray on an oil rig. As turbines
have become more efficient, they have become
more susceptible to damage from contaminants in
the combustion air. This ambient air from the
surrounding environment can contain high dust
loads. In California, with very tight emission
standards, the particulate in the inlet air to
the turbine can exceed emission limits. Thus,
the gas turbine has to act as an air cleaning
device.
The challenge for gas turbine
inlet fiber, media, and filter suppliers is to
increase gas turbine availability in all
environments with newer and more sensitive gas
turbines. The newer turbine designs are
negatively impacted by small particles. This has
led to the use of HEPA filters with efficiencies
classed as H10/E10 and higher. Studies show that
turbine maintenance can be reduced with even
higher efficiency E12-U17. One study showed that
even if the cost of higher efficiency filtration
were four times higher than lower efficiency
filters, the true cost would be lower.
One can choose a system with non-cleanable
filters. They are relatively inexpensive but
require continuous filter replacement. By using
a sequence of inefficient but inexpensive pre
filters and a final high efficiency filter, the
replacement cost can be minimized.
An alternative is to use a cleanable filter.
Periodic air pulsing knocks off accumulated
dust. These systems are available
from many suppliers if the F-9 efficiency is all
that is desired. Cleanable filters
with H12 efficiency are available from only a
few suppliers. On the other hand, there are many
new developments which will expand the number of
choices.
In terms of high efficiency dust capture
mechanisms there is a choice between wet laid
glass and synthetic nanofiber non-woven
laminates or membranes. The traditional glass
media for HEPA filtration has been used
primarily in non-cleanable filters.
Quantifying the benefit is a balance between
reduced fouling and increased pressure drop. The
increased pressure drop can be estimated to
restrict performance by approximately 0.4%,
while cutting fouling provides a 1.2%
improvement in output (empirical average).
Therefore, the overall result is a potential
efficiency improvement of 0.8%.
http://www.mcilvainecompany.com/GTairTech/Subscriber/Default.htm
Alliance Pipeline believes
that the E12 filters from Gore may
allow Alliance to extend the interval between
overhauls of its aero engines from 25,000 to as
many as 50,000 hours (from three to six years).
The many factors and media choices impacting gas
turbine inlet filter selection have
been discussed in a background document on
display at
In the past the most efficient filters that were
used on gas turbine inlets were rated F-9 with
efficiency of more than 95% on particles 0.4 um
diameter. The most penetrating particle size is
about 0.2 um where the efficiency is much lower.
Higher efficiency filters are rated based on the
most penetrating particle size as follows:
Membrane laminates such as used for dust
collection can meet efficiencies up to E12. The
question is whether this is sufficient?
There are a number of new filter and media
designs, which need to be evaluated. Mann
& Hummel Vokes introduced
the Aircube Pro Power S, which utilizes a new
synthetic base media with much higher resistance
to mechanical stress than glass fiber media and
a stable high efficiency during operation. It is
water and salt repellent while being extremely
robust.
DHA Filter has
introduced a cleanable HEPA filter for gas
turbine inlets, which it will be displaying at
Power-Gen.
Improving Limestone Scrubber Efficiency
U.S. and Indian FGD operators both are
interested in higher SO2 removal
efficiency. In the case of U.S. operators faced
with operating higher cost old plants, the
potential to cut pump-connected horsepower is
appealing. For Indian operators there is the
potential to reduce capital as well as operating
costs. Three options involve scrubber design.
scrubber chemicals, and optimization systems.
· A
spray tower with liquid flows as high as 100
gpm/1000 cfm and pressure loss of 3-6” w.g (MET,
Doosan, and many others)
· A
modified spray tower (MHPS)
· A
tray or rod deck scrubber with flows
less than 50 gpm/1000 cfm and pressure loss of
6-8” “ w.g. (B&W)
· A
sump scrubber with no liquid flow and pressure
loss of 9-11” w.g
Where there is enough fan capacity a tray or rod
deck can be added in a spray tower to increase
efficiency.
India is moving forward with approximately
100,000 MW of FGD systems. This will require
15-20 million of tons of limestone
per year. SHI-FW has conducted a study which
shows that because of the poor limestone a CFB
scrubber is the best choice for many plants
This analysis is based on a 300 MW
plant with 0.6% sulfur. Limestone cost is 7 rs
Crore /yr. ($989,000) based on 5 tons per hour
and a cost of limestone at 1750 rs./ton
($ 24.50/ton) vs EPA cost estimates based on
$30/ton. The tons/MW = 134.7.
Scrubber additives can improve the economics
when using a poor-quality limestone. One answer
is that if treatment chemicals can be justified
for a 0.6% sulfur coal, they will be even more
attractive for higher sulfur coals.
Brad Buecker of Chemtreat has reviewed this
analysis and concludes “With
regard to the analysis, the CaO range equates to
a calcium carbonate (CaCO3) range of
82 to 91 percent. A quick thought suggests
that this might be an excellent application for
ChemTreat’s DBA replacement product. A general
rule-of-thumb that I always followed is that
limestones with 94% or greater CaCO3 concentration
are usually quite reactive (if ground properly).
My gut feeling says that the stones outlined in
the analysis could be significantly enhanced in
reactivity using our FGD1105 product.”
Brad wrote an article in Power
Engineering earlier this month
where he provided further details:
“Many plants do not have access to such
high-purity limestones. The stone may contain a
significant concentration of dolomite (MgCO3∙CaCO3)
or inert materials that inhibit
reactivity. Thus, supplemental methods are
needed to boost the reactions. A common method
that has been used for years is addition of
dibasic acid (DBA) to scrubber process streams,
but new technology is improving upon this
chemistry. Dibasic acid is a generic name for a
blend of relatively short-chain dicarboxylic
acids (two COOH functional groups), which add
hydrogen ions (H+)
to help in the dissociation of limestone, and
then circulates through the process to continue
assisting with SO2-absorption
chemistry. However, the availability, cost, and
even efficiency of DBA has placed limits on the
chemical’s effectiveness. An alternative is
available that is much more promising for wet
FGD reactivity enhancement.”
Accordingly, the plant staff began full-scale
testing and then subsequent application of an
alternative, specially-formulated organic acid
blend with the product name of FGD1105 (patent
pending). Almost immediately upon chemical
addition, SO2 emissions
dropped by approxi- mately 35% to 40%, such that
even at full load one of the scrubber’s five
recycle pumps could be, and was, removed from
service. Stack SO2 emissions
only slightly increased from 120 lb./hr. to 200
lb./hr. following the pump reduction. This
action alone reduced auxiliary power consumption
by 3 MW, at a projected annual benefit of approximately
$700,000. As a test, the plant staff removed a
second recycle pump from service and found that
SO2 removal
was still more efficient than in the period
prior to the FGD1105 addition. According to Chad
Hufnagel, Longview’s Plant Manager, the ability
to operate with 3 recycle pumps instead of 4 or
5 has provided additionally flexibility for
recycle pump maintenance strategy, as well as
offering additional net revenue opportunity with
improved unit efficiency.
Therefore, the cost saving is more than
$700,000/yr. less the cost of the additive.
There are other questions to pursue such as
changes to wastewater treatment costs. This
analysis is based on a spray tower. If a tray
tower or rod deck scrubber is used, then the
saving would have to be in fan rather than pump
horsepower. Another question to be answered is
the parasitic cost of power for the average
Indian plant vs. that in the U.S.
The McIlvaine Coal Fired Power
Plant Decisions has a number of
relevant papers. They include INVISTA
DBA Dibasic Acid - The McIlvaine Company
www.mcilvainecompany.com/Decision_Tree/subscriber/Tree/DescriptionTextLinks/Richard...
There are a number of suppliers of DBA around
the world. They include
· Cathay
Industrial Biotech
· Palmary
Chemical
· Henan
Junheng Industrial Group Biotechnology
· Evonik
· Invista
· Zibo
Guangtong Chemical
FGD Scrubber Monitoring and Control: The
use of the right chemicals is only part of the
true cost reduction. Monitoring and control of
parameters is equally important. The CEMS system
should be used for process monitoring. In the
case above the system could operate with 3, 4,
or 5 pumps depending on the reactivity of the
limestone. However varying sulfur levels in the
incoming coal provide another variable. If SO2 is
measured prior to the scrubber as well as at the
stack the right balance between efficiency and
energy consumption can be determined.
The measurement of liquids is also important.
Brad Buecker addressed this subject in an older Power
Engineering article. He pointed
out that it is important to constantly measure
the alkalinity in the scrubber module or
modules, as too much alkalinity will waste
reagent while lean alkalinity will impair SO2 removal.
The technique universally employed in wet
scrubbers is pH monitoring. These measurements
must be continuous, with control of reagent feed
rates based upon the readings. For the lab
staff, grab-sample pH analyses are very
important to make sure that the in-line
probes/monitors are accurate.
The slurry circulating pumps can only handle so
much mass before electrical requirements are
exceeded. Like pH, scrubbers are equipped with
continuous density monitors, typically utilizing
radioactive detectors. Again, the lab staff
needs to monitor density on a grab sample basis
to ensure the accuracy of the continuous
instruments.
Control of solids chemistry offers interesting
challenges and is extremely critical to
operation. Experience has shown that operation
in either a completely oxidized state (no
calcium sulfite-sulfate hemihydrate in the
scrubbing slurry) or a completely un-oxidized
state (no gypsum in the slurry) minimizes
scaling in the scrubber. Scale buildups can be
extremely problematic, as deposit formation on
scrubber internals and subsequent gas flow
restrictions may cause unit de-rates and even
forced outages if gas flow is severely
restricted.
The technique that has proven itself very well
for scrubber solids analysis is thermogravimetry.
A thermogravimetric analyzer (TGA) is a
quantitative not a qualitative instrument, so
the operator needs to have a good idea of the
primary constituents in the sample before
analysis. If the sample compounds decompose at
distinct and separate temperatures, it becomes
easy to calculate the concentration of the
original materials. Wet-limestone scrubber
byproducts lend themselves well to this
technique.
The plant can vary the number of pumps in
operation. An optimization system
enables the plant to use the minimum number of
pumps required to keep the outlet SO2 lower
than limits. This also reduces the amount of
limestone slurry required, but the major
contributor to cost savings is cutting energy
use by removing one or more recirculation pumps
from service based on the input SO2 value.
One optimization system available was described
by Toshihiko
Fujii of Yokogawa
Electric Corp. in
a recent Power Magazine article.
FGD control is normally implemented by the
distributed control system through the
regulation of limestone slurry flow. The
limestone slurry flow is controlled based on the
pH value as measured by an analyzer installed in
the absorber. Typically, the pH value must be
controlled to ensure proper performance of the
desulfurization process in the absorber,
therefore the limestone slurry flow is
controlled to maintain the proper pH value. For
this control scheme, other indices such as the
FGD inlet and outlet SO2 are
not used, and all recirculation pumps are
operated regardless of the inlet SO2 value,
with slurry flow regulated by the control valve.
The optimization system typically consists of
three functions: enhanced regulatory control,
model-based prediction, and process value
prediction. The system uses these three
functions to continuously determine the minimum
required number of recirculation pumps in
operation, and to calculate the setpoint for the
limestone slurry flow PID
(proportional-integral-derivative) control loop.
A 700-MW coal-fired power plant in Japan
implemented the optimization system. This plant
runs about 300 days per year at baseload and is
not in operation for the other 65 days of the
year. The energy savings realized by running
only the required number of recirculation pumps
was 12.4% of the unit’s total house load,
equating to about $900,000 in energy savings per
year based on market conditions in Japan.
Another benefit was reduced pump run times,
which resulted in lower pump maintenance costs
and extended pump life. A third benefit was less
limestone usage.
https://www.powermag.com/advanced-process-control-for-optimizing-flue-gas-desulfurization/?pagenum=1
Last week we reported on this in the Alert. Flow
accelerated corrosion (FAC) can cause iron loss
in steam piping and lead to lethal accidents. As
a result, programs are necessary to reduce metal
loss and to monitor the loss which does occur. A
team from Danaher analyzed the
problem in a Power Engineering article
appearing in January 2019.
We cited the use of fine particle on line
monitoring. But here is more detail on the iron
measurement instrumentation:
Using advanced laser optics and signal processing, the instrument detects increased concentrations of submicron-sized particles that are a precursor to larger particles. This allows for early filter deterioration detection that meets or exceeds that of particle counters all with the day-to-day convenience, simplicity, and reliability of a Hach turbidimeter. Operators can detect impending filter breakthrough, delineate filter ripening, and maximize effective filter run time. The Hach TU5400 Laser Nephelometer can detect to 0.0001 NTU, providing operators with confidence in their turbidity measurement.
The TU5400 sensor can be used with any of Hach's sc Digital Controllers. Each sc controller accepts from two to eight sensors. Multiple controllers can be networked to accommodate many more sensors and parameters, reducing the cost per measuring point. Just plug in any Hach "plug and play" digital sensor and it's ready to use without software configuration. "Plug and Play" connectivity means there's no complicated wiring or set up. The TU5400 Nephelometer controller system now can manage multiple digital sensors.
Level and Flow Control are also important: Magnetrol
level and flow control are used in a number of
ways to optimize corrosion control. This
includes the ammonia storage tank, improving
heat rate efficiency through feedwater heater
level control and optimizing makeup water
treatment, energy management, steam generation
cycle, condensate and waste heat recovery.
Turbine Bypass
Valves Background Data Now
Available
The turbine bypass
system is a very important component of power
stations, and of a difficult service too.
Although it does not operate continuously, when
it is required to operate it has to be fast and
reliable. Its main job is called steam
conditioning. It means pressure reduction and
desuperheating of steam that has been produced
by the boiler but, due to transient or
unexpected conditions, cannot flow through the
turbine.
.
The percentage of
total steam handled by the turbine bypass system
depends on plant design philosophy. Capacity
usually ranges between 30% up to 100% of the
maximum continuous rating (MCR) boiler steam
flow. The high-pressure turbine bypass system
provides an alternate flow path at the
high-pressure side of the turbine, taking the
steam from the turbine inlet to the reheater
inlet section. This bypass system permits stable
operation of the boiler when the turbine trips
off line or during start-up operations. Steam
flowing through the high-pressure bypass control
valve is throttled and cooled to a temperature
slightly above the HP turbine exhaust
temperature, by spraying feed water at the
outlet of the bypass control valve. This flow is
then combined with high pressure exhaust steam
and passes through the reheater.
The low-pressure
turbine bypass system presents a flow path
around the LP turbine, taking steam from the
reheater outlet and conditioning it to be fed
into the condenser. For condenser protection,
high pressure and temperature drops are taken by
valve throttling and by the addition of large
amounts of desuperheating spray water,
preventing superheated steam from reaching the
condenser.
These are critical
valves and also expensive. The initial cost can
exceed $100,000 per valve. Operational and
maintenance costs can be substantial. Problems
and variables include
Noise
Plug valve sticking
Leakage
Optimal bypass % range
Reaction time
Materials for LP vs. HP vs. new conditions, such
as cycling or ultrasupercritical conditions
Multi-stage pressure reduction to reduce trim
wear
Stellite delamination
Flow accelerated corrosion
Maximizing power output
There are a few relevant speeches and some
exhibitors, such as Emerson and SPX, which
manufacture turbine bypass valves. Other
suppliers, such as BHGE, will be participating
in the networking resulting from the tour guide.
The stand and networking details have been
provided and will be updated.
In addition, two background documents have now
been added:
Turbine Bypass Valve Suppliers
http://www.mcilvainecompany.com/PowerGen_2019/Turbine_Bypass_Valve_Suppliers_10-31-19.pdf
Turbine Bypass Technology and
Applications
These documents will be expanded prior to the
conference and then on a continuing basis.
The Guide to True Cost of Gas Turbine Inlet Filters will be used to facilitate discussions at a number of events in the coming months. It will be used along with a tour guide on the subject at the PowerGen exhibition in November.
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