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SUMMARY OF FILTER SELECTION FOR THE SDSU POWER PLANT ABSTRACT A proposed update to the existing turbine inlet air filtration for the cogeneration plant at San Diego State University in order to increase efficiency, reduce energy consumption, and lower annual expense. Aaron Leftwick Advised by Professor Asfaw Beyene, PhD

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Page 1: Filter Selection w Window Filter Assembly

SUMMARY OF FILTER

SELECTION FOR THE

SDSU POWER PLANT

ABSTRACT A proposed update to the existing

turbine inlet air filtration for the

cogeneration plant at San Diego

State University in order to

increase efficiency, reduce energy

consumption, and lower annual

expense.

Aaron Leftwick Advised by Professor Asfaw Beyene, PhD

Page 2: Filter Selection w Window Filter Assembly

Summary of Filter Selection for the SDSU Power Plant

1 | L e f t w i c k

Existing Filtration:

The current filtration in place at the San Diego State University power plant is such that;

for rudimentary particulate removal, there is wire mesh surrounding louvres on the exterior of

the building as well as preceding the final stage filter set

(Figures 1 and 2),

for large particulate filtration there are

window coverings for all of the fourteen peripheral openings of the building to the ambient but

these do not have any sort of visible filtration performance rating

(Figures 3, 4 and 5),

for the pre-filtration there are sixty-six

pre-filters in place preceding the final stage F8 filter set which are of MERV 8 rating

(Figure 6), and for fine particulate separation, ultimately the final stage, there

are thirty-two cylindrical and conical filter sets. According to an employee of the plant the filters

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are documented as being of F8 rating but this could not be indefinitely verified without taking a

turbine off-line to inspect inside the filter housing.

The window coverings are visibly dirty most of the time indicating the need for adequate

filtration at that location in order to minimize particulate and dust from entering the interior of

the plant which houses everything from the turbines to the switchgear so, needless to say dirty

conditions are not suitable. The pre-filtration in place, even if it were to be taking in perfectly

clean air provided by adequate filtration on all passages, would still have issues pertaining to the

sealing of the filters to the housing which is at best allowing half of the air through the filter while

allowing the other half to pass around the filter through what should be a seal between the

housing and the filter

(Figures 7 and 8).

Also, the MERV 8 rated filter

itself is inadequate as a pre-filter as it only removes about 70% of the particles at the three to ten

micron size and has no rating for smaller particles. At an average separation efficiency of less

than 90Am when properly sealed these filters still allow approximately 99% of all atmospheric

particles through since 99% of atmospheric particles are less than one micron in size. The final

set of F8 filters, which have been determined to not be receiving clean air to any extent from

either of the first two filter sets, were the industry standard prior to the use of EPA (efficient

particulate air filter) or HEPA (high efficiency particulate air filter) filters. Unfortunately, F8 filters

are vulnerable to sub-micron and salt penetration whereas the 3 stage HEPA filters are hydro-

phobic and are not easily penetrated by sub-micron sized particles.

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Summary of Filter Selection for the SDSU Power Plant

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Existing pre-filtration:

(Figure 9)

The details of the existing Air Handler pre-filters can be found at

http://www.grainger.com/product/AIR-HANDLER-High-Cap-Pleated-Filter-6B975 and are as

follows;

“50% more surface area than standard capacity extends service life by 30% to 50%, providing reduced resistance and lower

energy and maintenance costs. 5 times more efficient than fiberglass filters. Wire-backed design. Die-cut frame. 100%

synthetic media.”

Technical Specs

Item High Capacity Pleated Filter

Nominal Filter Size 12x24x2

Nominal Height 12"

Nominal Width 24"

Nominal Depth 2"

MERV 8

Frame Type Moisture Resistant Die Cut Chipboard

Nominal Pleat 0.4

High Velocity 500 fpm

High Initial Resistance 0.30"WC

Final Recommended Resistance 1.0"WC

Max. Velocity 500 fpm

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Media Area 8.7 sq. ft.

Max. Temp. 180 Degrees F

Pleats per Linear Feet 15

Standards UL 900 Classified

Actual Height 11-3/8"

Actual Width 23-3/8"

Actual Depth 1-3/4"

Green Environmental Attribute Product Contributes to Reducing Energy Consumption

Existing final stage filtration:

(Figure 10)

The details of the existing Donaldson final stage filtration can be found at

http://www.donaldsonlatam.com/cont/images/pdf/Gts/GTS-400_Catalog%20-

%20Catalogo%20Completo%20%282%29.pdf and are as follows;

“Synthetic (Donaldson’s man-made fiber filter media) - In controlling the fiber diameter and the pore size, we've designed

this proprietary filter media to be effective in various environments (desert, arctic/frost, urban, industrial, marine, etc.)

The smooth fibers provide very low impedance to airflow -- helping to maintain low ∆P for the entire life of the filter.”

Technical Specs

Donaldson

Mfr. # P19-1033 (cylindrical)

Mfr. # P19-1107 (conical)

Synthetic Media

F8/MERV12

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Considered Filters:

For the final stage filtration we are considering a few filter types including; the GORE Turbine

Filter ePTFE, H12/E12 rated, conical and cylindrical filter sets, these filters can be located at

http://www.gore.com/en_xx/products/filtration/turbine/turbine_filters_cylindrical_conical.ht

ml

(Figure 11),

The AAF HydroShield filter, H12/E12 rated, conical and cylindrical

filter sets, these filters can be located at http://www.aafgtsolutions.com/_lib/files/hepa-

technology/aaf_hydroshield_brochure.pdf

(Figure 12).

For the pre-filtration stage we are considering the following; 3M Mini-Pleat Filter with Gasket,

MERV 14 and MERV 11, 12x24x2, Mfr. Model # F978 and # E279, which can be found at

http://www.grainger.com/product/3M-Mini-Pleat-Filter-w-Gskt-4DZH4?opr=APPD&pbi=4DZF5

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(Figure 13),

the Air Filters Incorporated Pockit Loc particle bypass block, MERV

13, 12x24x2, Mfr. Model # POC131224215, these filters can be found at

http://www.airfilterusa.com/12x24x2-pockit-loctm-merv-13-particle-bypass-block-high-

capacity.html?gclid=CjwKEAjw3sKpBRDJ7rDqzsyuhDASJACZAikiY-

C7Cgq7tJXOBZyexE97Yjh9pw7W7BlIW_qSQd-LRBoCU7zw_wcB

(Figures 14 and 15).

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All considerations for pre-filtration and final stage filtration are direct replacements to the

existing filtration currently in place therefore will not require any modification of air inlet

housing.

Selection Criteria:

The selection criteria for the proposed final stage filter change can be easily viewed with use of the flow chart below provided by Donaldson (Figures 16 and 17), the manufacturer of the current final stage filtration at the plant, below indicates that the final stage filters currently in place are not adequate to properly filter the contaminants that are seen specifically at the SDSU power plant due to smog and the coastal environment (Figure 18) in which it is located based upon Donaldson’s own standards, therefore our selection criteria is also based upon the suggestions of the filter manufacturer the plant is currently using. If the manufacturer of the filter is indicating that their product will not work in our application efficiently it does not seem logical to further the use of that filter type. This chart can be viewed at http://www2.donaldson.com/torit/en-us/documents/cartridge-filter-selection-guide.pdf.

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The details of the GORE Turbine Filter ePTFE are as follows;

GORE® Turbine Filters – Conical & Cylindrical Filter Pairs - E12

More Power

GORE® Turbine Filters optimize power output by eliminating performance reducing deposits in your compressor section.

Their outstanding E12 filtration efficiency keeps out at least 99.5% of contaminants at the most penetrating particle sizes

(~0.1 μm). This stops power losses while reducing your fuel consumption and associated CO2 and NOx emissions. Machine

availability and reliability are also significantly increased because there is no need to stop the turbine for off-line

compressor washing.

Less Wear

GORE® Turbine Filters significantly reduce your maintenance costs while increasing compressor and turbine lifetimes.

Unlike current air intake filters, they capture at least 99.5% of atmospheric particles, and have a unique patented filter

media that is waterproof and provides reliable protection from corrosive salts. This reduces unexpected failures and major

outages by preventing both fine and corrosive particulates from reaching the engine. GORE® Turbine Filters also directly

replace your existing filters with no modifications required to filter housing.

Features

>99.5% Filtration Efficiency at MPPS (E12)

Very Low Initial Pressure Drop

Watertight and Salt Repellent

High Burst Pressure

Benefits

Higher Power Output

Increased Turbine Availability

No Filter House Modifications Required

Less Fuel Costs

Less Maintenance Costs

Construction Materials

Filter Media: Fully Synthetic Composite with ePTFE Membrane

Endcaps: Galvanized Steel

In-/Outside Liner: Galvanized Steel

Potting: Polyurethane

Gasket: EPDM Rubber

Application Performance

Efficiency: E12 according to EN 1822 Min. 99.5% @ MPPS

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Wet Burst Pressure: 7500 Pa (30" wc)

Initial Pressure Drop: 180 Pa @ 2500 m³/h (.72" wc @ 1472 cfm)

Temperature Range: -40°C to +65°C (-40°F to +149°F)

Humidity Range: 0 to 100% relative humidity

Flame Retardance: E d2 according to EN 13501

Dimensions

Conical Cylindrical

Large End OD: 445 mm (17.5") 323 mm (12.75")

Small End OD: 323 mm (12.75") 323 mm (12.75")

Length: 660 mm (26") 660 mm (26")

Other sizes available upon request.

Direct replacement of most conventional filters with no modifications required to filter housing.

Operational Mode - Pulse cleanable and static

The details of the AAF HydroShield are as follows;

“AAF’s HydroShield multi-layer composite membrane is designed to offer maximum protection in environments where

excessive moisture, salt and hydrocarbons are prevalent. AAF’s extensive expertise has allowed us to perfect multi-layer

filter construction. The combination of hydrophobic and oleophobic pre-filters, depth-loading HEPA membrane and

advanced substrate creates an unbeatable blend of water resistance, effective filtration and innate strength.

Depth-Loading Filtration Technology

HydroShield employs a specially designed multi-layer media with unique depth-loading membrane technology that acts as

a reservoir for oil, hydrocarbon and dust capture. The media has been optimized to offer E12 HEPA efficiency grades. Unlike

many comparable filters, HydroShield’s depth-loading membranes resist the “wetting” that is prevalent in PTFE media, a

process in which captured oil binds the membranes together, rapidly increasing differential pressure and reducing useful

life.

Water and Salt Repellent

To properly maintain power and efficiency in even the most arduous conditions, a gas turbine filter must resist not only

dust and dirt, but also repeated exposure to fog, moisture and salt spray. To make sure HydroShield filters exceed

expectations in any application, AAF created a purpose-built testing facility to simulate the harsh, damp conditions found

in coastal and offshore marine locations. By testing seawater resistance in a variety of applications, AAF has been able to

create a barrier that can deliver consistently excellent results regardless of the type and quantity of moisture present.

Optimal Media Pleating

AAF HEPA/EPA filters are perfected down to the last detail. Even the pleating in the filter media has been optimized to

ensure low airflow resistance and high dust-holding capacity. The media is uniformly spaced by synthetic glue beads to

present a consistent, open structure. The lower stabilized pressure drop this creates will recover power and save fuel, while

the open-pleat geometry protects against media bridging during excessive moisture exposure.

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Lower, Stabilized Pressure Drop

Depth-loading media results in a lower initial pressure drop coupled with better dust capture and distribution during

operation. This lower pressure loss reduces associated energy costs through fuel savings.” The details of the 3M Mini-Pleat Filter with Gasket are as follows;

“Low pressure drop helps reduce energy consumption. Allow simple upgrade of existing filters. Innovative

combination of depth loading filtration media, precision pleat structure, and high filter media area result in longer filter life.

Durable 100% synthetic filtration media resists moisture and humidity. Filters are 100% metal-free and fully incinerable.

Factory installed integral gasket. ”

Technical Specs

Item Mini-Pleat Filter with Gasket

Nominal Height 12"

Nominal Width 24"

Nominal Depth 2"

MERV 14

MERV-A 12

Initial Resistance 0.37" WC

Med. Initial Resistance 0.25" WC

Final Resistance 1.4" WC

Recommended Final Resistance 1.4" WC

Frame Type 2" Plastic

Filter Pack Enclosure 100% Synthetic Frame, Lightweight, Resists Moisture, Integral Seals

Air Flow 492 fpm

Medium Velocity 375 fpm

Max. Air Flow 625 fpm

Max. Temp. 122 Degrees F

Avg. Atmospheric Efficiency 90 to 95%

Material Synthetic

Media Area 52 sq. ft.

Pleats per Linear Feet 60

Standards UL 900 Class 1

Green Environmental Attribute Product Has MERV Rating of 13 or Higher

The details of the Air Filters Incorporated Pockit Loc filter are as follows;

“Until now, the only marginally adequate solution to HVAC particle bypass was time-consuming installation of

tape or messy, unmanageable and unreliable foam gaskets. Our filtration engineering specialists in recognizing and solving

filtration issues designed a comprehensive cost-saving solution.

Air Filters Incorporated™ Pockit-Loc™ MERV 13 12x24x2 seasonal (Up to 3 Months) Expanded Metal Backing high

capacity pleated filters utilizes electrostatically charged, 100% synthetic media which offers significantly higher particulate

efficiency than regular poly/cotton media pleated filters, with little change in static pressure. Pockit-Loc™ MERV 13 filter

media will not promote the growth of bacteria, mold, mildew, or fungi in normal operating environments, and has not been

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chemically treated. Pockit-Loc™ MERV 13 pleated filters are an ideal upgrade from standard disposable panel filters. These

filters are designed to last up to 3 months.”

Technical Specs

2-Inch Pre-Filter

High Capacity

Panel Filter

3 Month Filter

Disposable

Arrestance 99%

Dust Efficiency 55%

ASHRAE Efficiency 85%

MERV 13

Bank Frame

Moisture Resistant

Selected/Ranked Filters:

For the final stage filtration we propose the use of GORE Turbine Filter ePTFE filters as the first

and optimal choice followed by the AAF International HydroShield filter. All final stage filters

proposed are E12/H12 rated conical and cylindrical filter sets.

The reasons for the choice of final filtration:

1. The performance rating of the proposed GORE Turbine Filter ePTFE is E12/H12 and

captures 99.5% of all atmospheric particles whereas the existing Donaldson final stage

filtration, which is rated at merely F8, captures particles from 1.0 to 10.0μm at an average

efficiency of greater than 90% as well as particles from the 0.3 to 1.0μm range at an

average efficiency of 75 to 85% and because 99% of all atmospheric particles are smaller

than 1.0μm concluding that the existing F8 filtration captures .75 to .85% of all

atmospheric particles.

2. While being the secondary choice, the performance rating of the proposed AAF

International HydroShield filter is E12/H12 and when compared to the existing Donaldson

final stage filtration with F8 rating the results are the same as when compared to the

GORE Turbine Filter ePTFE therefore this filter is also a better option than what is

currently in place.

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3. Both the GORE Turbine Filter ePTFE and the AAF International HydroShield filter are

hydrophobic (water resistant), resistant to salt penetration, and resistant to sub-micron

as well.

4. The prices of the GORE Turbine Filter ePTFE and the AAF International HydroShield filter

are not advertised and require contacting the manufacturer.

W. L. Gore & Associates, Inc.

Toll Free (U.S.) 1 800 523 4673

AAF International Building

9920 Corporate Campus Drive, Suite 2200

Louisville, KY 40223-5000, USA

Tel: +1 502 637 0408

Toll Free: 888 AAF 3596

Fax: +1 502 637 0147

For the pre-filtration stage we propose the use of the 3M Mini-Pleat Filter with Gasket filters as

the optimal choice followed by the Air Filters Incorporated Pockit Loc provided these filters will

work without any modification to the existing housing. All pre-filters proposed are of MERV 11

rating or higher.

The reasons for the choice of pre-filtration:

1. The performance rating of the proposed 3M Mini-Pleat Filter with Gasket is MERV 14 and

when compared to the existing Air Handler filter which is rated at MERV 8 the average

efficiency gain in filtration for the 3.0 to 10.0μm particle size is 20% which is a phenomenal

increase in filtration capability just for the large particle range.

2. The 3M Mini-Pleat Filter with Gasket also captures particles from the 1.0 to 3.0μm at an

average efficiency of greater than 90% as well as particles from the 0.3 to 1.0μm range at

an average efficiency of 75 to 85% which the Air Handler filter captures none of therefore

the increase in particulate separation within these particulate size ranges is infinitely

more.

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3. The 3M Mini-Pleat Filter with Gasket again is a viable solution for the reason it is made to

have a gasket in order to soak up the clearance issue and add to the total amount of air

passing through the filter instead of around it.

4. The individual, non-bulk, retail cost of the 3M Mini-Pleat Filter with Gasket when

compared to the Air Handler at www.Grainger.com is $147.73 versus $8.70 respectively

which is a substantial increase per filter but would eliminate the need to re-seal many

portions of the filter housing reducing labor costs.

5. The 3M Mini-Pleat Filter with Gasket will be able to be installed and put into use

immediately without any modification to the existing housing while still adding to the

overall increase in air filtration efficiency.

6. With a more sound mechanical seal and the higher MERV rating these filters will better

the intake air quality preceding the final stage.

7. Other pre-filtration options will be included in the table below.

Filtration Pre-Filtration Final Stage

Brand Rating Cost Brand Rating Cost

Current Air

Handler

MERV 8 $8.70 Donaldson F8 (Prices can be

obtained by

contacting the

manufacturers)

First Choice 3M MERV 14 $147.73 GORE E12/H12

Second Choice 3M MERV 11 $77.20 AAF E12/H12

Third Choice Pockit

Loc

MERV 13 $9.31 N/A N/A

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We are also Proposing:

Properly sealing any remaining air leaks in the pre-filter housing assembly on the interior

of the building (Figure 19) with gasket material which can be

purchased at http://www.grainger.com/product/AIR-HANDLER-Air-Filter-Gasketing-

6C524?functionCode=P2IDP2PCP for a retail cost of $18.42 for fifty feet.

Technical Specs

Item Air Filter Gasket

Length 50 ft.

Width 13/16"

Depth 1/4"

Color Black

Max. Temp. 220 Degrees F

Manufacturing of the window frame assembly that has been modeled in SolidWorks

which is to be mounted to the wall with cement anchors covering the window opening

and would house a number of 12” x 24” x 2” MERV rated air filters. The window filter

assembly contains a quick release mechanism in order to reduce the time taken to replace

the filters as well alleviate the added labor cost associated with a more timely process

(Figures 20 and 21).

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Alternatively, installing performance rated window screen filters opposed to the use of

the non-rated window coverings which are currently in place. This MERV 5 rated window

filter

(Figure 22)

can be purchased at http://www.grainger.com/product/AIR-

HANDLER-Filter-Media-Roll-

30PT34?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/6B685_AS01?

$smthumb$ for $178.00 per roll.

Technical Specs

Item Filter Media Roll

Length 65 ft.

Width 32-7/8"

Nominal Thickness 1/2"

Actual Thickness 2/5"

MERV 5

Initial Resistance 0.04" WC

Final Resistance 0.50" WC

Core Type AE/CB

Material Polyester

Color Varies

Standards UL Class 900

Sealing of any air leaks between the ambient, or exterior of the building, and what should

be the pre-filtered air contained within the plant itself.

Closing any doors or windows and applying coverings to any unfiltered openings

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(Figure 23).

Use of proper door seals around the perimeter of the doors, especially the base of the

doors, and can purchased at http://www.homedepot.com/p/Unbranded-36-in-x-84-in-

Screw-in-Door-Perimeter-Seal-Heavy-Duty-for-Doors-WS3684/202510613 for $65 retail

(Figures 24, 25, and 26).

Technical Specs

DIMENSIONS

Assembled Depth (in.) 1.5 Product Height (in.) 84.0

Assembled Height (in.) 84 Product Width (in.) 36.0

Assembled Width (in.) 36

If possible, relocation of the inlet air.

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References:

Melissa Wilcox, Rainer Kurz, Klaus Brun “Technology Review of Modern Gas Turbine Inlet

Filtration Systems” International Journal of Rotating Machinery Article ID 128134 (2012)

Michael Wofford advised by Professor Asfaw Beyene, PhD “Co-Generation Plant Inlet Air

Purification”

James DiCampli, P.E., Jack Pan, GE Power and Water, Mark Arsenault, American Air Filter “Gas

Turbine Air Filter System Optimization” Power Engineering www.power-eng.com (1/21/2015)

“Modern Power Systems” www.MODERNPOWERSYSTEMS.COM (September 2010)

“Guideline for Gas Turbine Inlet Air Filtration Systems” Gas Machinery Research Council

Southwest Research Institute Release 1.0 (April 2010)

James Kenneth Ross “The Economic Benefits of HEPA-grade Filtration for Gas Turbine Operation

in the Power Generation Industry” AAF Power and Industrial (2012)

Wilson Poon, Matthew Gessner, Steven Medvetz “Dramatic Reduction of Gas Turbine Fouling

with HEPA Composite Membrane Air Intake Filters” Proceedings of the Thirty-Ninth

Turbomachinery Symposium W.L. Gore and Associates, Inc. (2010)

Rob McMahon, Ryder Pingry “500,000 Hours of HEPA, A Case Study with Surprising Implications”

WTUI Alliance Pipeline, W.L. Gore and Associates, Inc. (2015)

Team CCJ “The Value Proposition Offered by HEPA Filtration” Combined Cycle Journal (March 6,

2014)