Pioneer Air Systems - Specializing in Air, Water & Gas Processes Since 1980 www.pioneerair.com

210 Flatfork Road Wartburg, TN 37887 USA

(423) 346-6693 www.pioneerair.com

DCR SILOXANE AND VOC REMOVAL

FROM LANDFILL AND ANAEROBIC DIGESTER BIOGAS STREAMS

SILOXANE - is a term coined by a British chemist in the 1930’s for – polyorganicsiloxanes. Polyorganicsiloxanes are 100% man-made compound that have characteristics of low toxicity, low flammability, low surface tension, water-repelling properties and high thermal stability. Siloxanes are used in production of personal care products, clothing, food products, packaging, building materials, autos, etc. However, these same beneficial characteristics in consumer products are highly detrimental when siloxanes are volatilized and entrained in biogas streams. During combustion of biogas the volatile siloxanes are converted into solid silicon dioxide leading to the build-up of layers of deposits that inhibit heat conduction or lubrication in engines, turbines and burner tips, affect the geometry of combustion chambers, and clog flow lines and/or poison catalysts. Removal of all siloxanes ‘species’ is important to minimize downtime and expensive repairs to engines, turbines and boilers. It has been shown that siloxane removal can extend lubricating oil life by multiples of hours and can save from tens of thousands to hundreds of thousands of dollars in maintenance costs on an annual basis, not counting lost productivity. The commercial removal of siloxanes began in the early 1990’s utilizing a solvent-based system that required significant electrical and filtration loads and did not specify the species of siloxanes targeted. Increases as the expansion of renewable energy projects at landfills and wastewater digesters increases worldwide, the damage caused by siloxanes to reciprocating engine, turbines and recuperators and burner tips is increasingly evident.

Pioneer Air Systems - Specializing in Air, Water & Gas Processes Since 1980

Siloxanes are either linear (L) or cyclic (D) compounds with the following characteristics:

Mol Wt At 25 C or 77 F

SPECIES G/mol Solubility in Water

Vapor pressure

(psi)

Melting Point

(F)

L2 162.4 930-+ ppb at 73F 0.597555 -88.6

L3 236.5 56 +-ppb at73F 0.075419 -115.6

L4 310.7 6.7 ppb @ 73F 0.010587 -90.4

L5 384.8 7.1 ppb@73F 0.001305 -113.8

D3 222.46 may decompose in water 0.165343 147

D4 296.64 56ppm at 73F 0.018854 63

D5 370.8 17ppb at 73F 0.007251 -47

D6 444.93 .00513 mg/l 0.000435 26.6

SOURCES OF SILOXANES

SPECIES SOURCE

L2 antifoaming, antistatic emolient, skin conditioner

L3 skin conditioner

L4 sealants, paint, lacquer, varnish, hydraulic fluid

D3 hair conditioner, emolient, solvents

D4

polishing agent, antistatic, emolient, humictant,

etc

D5 dry cleaning fluid, industrial cleaner, car wax

D6 hair conditioner, emolient, solvents

Pioneer Air Systems - Specializing in Air, Water & Gas Processes Since 1980

There are three primary methods of removing siloxanes – consumable media, regenerative media and deep chilling. These may be compared as: Consumable Media Regenerative Media Pioneer Air DCR Dehydration pre unit Yes Yes No Flare removed compounds No Yes No Media rendered flammable Yes Yes No Media deemed hazardous on disposal Yes Yes No Electricity required No Yes Yes In media-based siloxane removal systems the media has preferential rates of attraction for certain siloxane species. However, this selection is affected by the amount of moisture in the biogas as all media has an initial preference for moisture. Linear species are normally the first to be adsorbed to media. As the cyclic species accumulate, the linear species are often driven off the media and reintroduced into the processed biogas stream with the result of exposing downstream equipment to siloxanes. This is true for both consumable and regenerative media.

Pioneer Air Systems - Specializing in Air, Water & Gas Processes Since 1980

Consumable media is just that….as the media becomes saturated with siloxanes, etc. it is ‘consumed’ and requires replacement. As the media comes in contact with elements from landfill or digester gas it is becomes classified as hazardous and requires disposal in a special hazardous waste landfill. This more than doubles the cost of the original media on a ‘round trip’ basis. Regeneratable media utilizes a cocktail of media types to capture siloxanes in a pass-through bed. When the media is saturated with siloxanes, etc. the biogas is shifted to a parallel vessel and the original vessel is heated to drive off the captured siloxanes with the regeneration gas taken to a flare for disposal. In this process energy is consumed either as a parasitic load to the system or from purchased energy. Either way is an economic cost. Empirical evidence shows that any media which is subject to heated regeneration does not return to 100% efficacy, hence a decline curve requires the replacement and disposal as a hazardous substance. Additionally, the destruction flare will become the source of combustion which converts siloxanes to silicon dioxide and requires the equipment shut down for cleaning annually. Pioneer Air Systems patented (US6,712,885) Deep Chilling Removal (DCR) siloxane removal system is unique in that it utilizes no media and has no emission discharge that requires a flare or thermal oxidizer to destroy the captured constituents. Alternatively, the siloxanes and VOCs are contained in the aqueous discharge of the system and are either returned to the leachate system of a landfill, returned to a digester or filtered out with the final discharge being a POTW water stream. The DCR is elegant in its simplicity.

Pioneer Air Systems - Specializing in Air, Water & Gas Processes Since 1980

The incoming fully saturated with moisture biogas enters the unit via a gas/gas heat exchanger at ~120oF (49oC) and is cross exchanged with the outlet treated biogas from the DCR unit at -10oF (-25oC). Without any additional energy consumption, the inlet gas is chilled to ~38oF (3OC). The bulk of the moisture in the raw biogas is removed at this point and is collected in a discharge vessel. The chilled biogas then enters the initial chilling shell and tube heat exchanger with the biogas in the tube side and -35oF/-350C glycol in the shell side. As the moisture entrained the biogas begins to freeze within the tube, the siloxanes and VOCs with melting points and vapor pressure above -10oF are captured in the ‘ice’. In addition, the pressure and decreased temperatures in the tube side the solubility of other siloxanes is altered such that they are captured as well. On either a timed event or registration of a change in pressure, the biogas is shifted from the initial heat exchanger to a second, parallel heat exchanger to duplicate the process. At this point a slip stream of the warmed glycol is introduced into the shell side of the initial heat exchanger to begin the process of ‘defrosting” the heat exchanger. As the tube side is warmed, siloxanes and VOCs with higher vapor pressure are released and vented from the tube. The balance of the siloxanes and VOCs are carried out in an aqueous stream to a discharge vessel for disposal. When the tube is fully evacuated, the shell side is flooded again with -35oF glycol to pre-cool the heat exchanger for the next cycle. Each cycle usually takes about two hours. There is no interruption to the flow of biogas treated in this system. The DCR system is proven to remove 96-97% of all siloxanes present in the inlet gas without media treatment. Accordingly, an inlet level of 1000ppm of siloxanes is reduced to 30ppm with a single treatment. If a lower level is required, such as for biogas fuel to an engine with a selective catalyst on the exhaust, a small carbon polishing bed may be installed. This sacrificial bed is very small as the inlet gas has a PDP of -10oF/-3oC and only 3% of the inlet siloxanes require capture. These siloxanes are normally a linear species.

System treating 1500scfm in support of DCR on Offshore Platform 3 Waukesha engine gen sets for heavy hydrocarbons

Pioneer Air Systems - Specializing in Air, Water & Gas Processes Since 1980

The DCR system treats biogas prior to a beneficial use, whether it is electric generation, boiler burner tip or pre-treatment prior to making high Btu pipeline gas in the most economic manner available. The DCR units only require glycol pumps and refrigeration compressors as an energy cost, with no media cost nor emissions requiring permitted destruction. All elements are controlled by a PLC with Pioneer in-house programming. Interface with SCADA systems of overall plants is easily accomplished. Additionally, VPN systems may be installed to allow for remote monitoring or troubleshooting by client and Pioneer engineers. These units may be tailored to the specific biogas producer requirements:

DCR for Indoor Installation DCR Enclosure with canopies for harsh environment

Model No

KW +/- 10%

SCFM @ 100 PSIG NM

3/H @ 7 BARG

SCFM @ 7 PSIG NM

3/H @ 0.5 BARG

In/Out "/mm FLG

L x W x H Inches / mm

Ship Wt Lb /kg

DCR5T 6 300 510

100 170

2 50

72 x 48 x 96 1800 x 1200 x 2500

3000 1364

DCR8T 10 480 816

160 272

3 75

96 x 72 x 96 2440 x 1800 x 2500

5000 2273

DCR10T 12 600 1020

200 340

3 75

120 x 90 x 96 3000 x 2300 x 2500

8000 3636

DCR15T 20 900 1530

300 510

4 100

150 x 90 x 96 3800 x 2300 x 2500

11000 5000

DCR20T 25 1200 2040

400 680

6 150

210 x 90 x 102 5400 x 2300 x 2600

14000 6364

DCR25T 30 1500 2550

500 850

6 150

240 X 90 X 102 6100 x 2300 x 2600

17000 7727

DCR30T 35 1800 3060

600 1020

6 150

270 x 90 x 102 6900 x 2300 x 2600

20000 9091

DCR35T 40 2100 3570

700 1190

8 200

300 x 90 x 108 7600 x 2300 x 2800

24000 10909

DCR40T 45 2400 4080

800 1360

8 200

330 x 90 x 108 8400 x 2300 x 2800

27000 12273

DCR45T 50 2700 4590

900 1530

10 300

360 x 90 x 120 9200 x 2300 x 3000

31000 14091

DCR50T 60 3000 5100

1000 1700

10 300

390 x 90 x 120 9900 x 2300 x 3000

34000 15455

DCR55T 70 3000 5100

1100 1870

10 300

420 x 90 x 120 10700 x 2300 x 3000

37000 16818

DCR60T 95 3600 6120

1200 2040

10 300

450 x 90 x 120 11500 x 2300 x 3000

40000 17727

Pioneer Air Systems - Specializing in Air, Water & Gas Processes Since 1980

The DCR- Deep Chilling Removal system shall provide clean & dry ………SCFM/NM

3/H of Bio/Digester/Land-fill gas at ……..PSIG/BARG.

The system shall remove 96 % or more of the contaminants, including moisture and SILOXANES, from the fuel gas, without using a carbon media. It shall chill and dry the fuel gas to -10

0F (-23

0 C) temperatures to condense and remove moisture, SILOXANES and other

contaminants. The system shall be factory integrated & include –

• Class 1, Division 1/2 and Group D Electrical Control Panel & Wiring

• Fusible Disconnect or Circuit Breaker

• Control Panel: Separate for installation in a safe area, or, NEMA4X/7, installed on the skid Voltage: 460-3-60 or as required AB /Siemens PLC to control Fuel Gas and Refrigerant, temperatures and pressures at critical points Motor Starters/ Contactors: separate for installation in a safe area, or, installed on the skid ROSEMOUNT Pressure & Temperature Transmitters Safety features - High Refrigerant pressure / temperature warning & shut down High Fuel Gas pressure / temperature warning & shut down Circuit Breakers/Fuses PRV Ethernet connector for remote monitoring & control A/B Touch screen (HMI) indicates - Power On / Off Fuel Gas Temperature and Pressure at all critical points Refrigerant Temperature and Pressure at all critical points Blower/Compressor status Refrigeration system status Cause of system/component shut down Control settings/adjustment Liquid level in all separators & filters Drain valve status Fuel Gas flow (SCFM)

• Gas compression package (blower / compressor) complete with - Fuel Gas flow & pressure control Capacity control: 25 % to 100 % 316 SS Inlet Filter-Scrubber & drain valve High liquid level alarm & shut down Back pressure regulating valve 316 SS After cooler, moisture Separator & drain TEFC Motor, HP-- Motor Controls & Overload protection VFD, NEMA1, separate for installation in a safe area, or, NEMA4, installed on the skid

• Gas flow thru 316SS (except blower/compressor)

• 316 SS Gas to gas heat exchanger to pre-cool incoming fuel gas; and, to re-heat out going fuel gas to within 30 °F of the inlet

gas temperature (Economizer # 1)

• 316SS Moisture evaporator - Cools incoming gas & saves energy (Economizer # 2)

• 316 SS Gas to refrigerant heat exchanger, cools incoming fuel gas to 35 to 40 0F (Stage 1 refrigeration)

• Duplex, alternating gas-refrigerant heat exchangers to chill gas to -10 0F (-23

0 C); one heat exchanger cools gas while the other

is de-frosted to remove siloxanes and other contaminants, and, provide continuous flow of clean and dry gas (Stage 2 refrigeration)

• A set of PLC actuated valves to direct fuel gas flow to one of the two alternating heat exchangers

• A 0.01 micron “cold point” coalescing filter for maximum removal of contaminants

• A set of PLC actuated glycol valves to direct cold glycol to one heat exchanger to cool gas; and, warm glycol to the other heat exchanger to de-frost it

• Environment friendly refrigerant, R404a or R134a or approved equal

• For maximum efficiency, system shall cool gas in multiple steps; and, use condenser heat for de-frosting

• System shall be "air cooled with fan cycling control" / "Water cooled with water flow control"

• Equipment shall include multiple hot gas by pass valves to control gas temperature

• Equipment shall include refrigerant sight glass & moisture indicators

• FINAL POLISH FILTERS (if required): The system shall include --- Number of vessels...; Number of Final Filters; Vessel size (D x H)...; Vessel material...; Media quantity...

• The system shall provide following signals for remote monitoring & control.........

• System shall include an automatic drain at each separation point

• The system shall be blast cleaned, primed and epoxy painted

• Single point electrical connection, within 6" of the edge of the equipment

• Five-Year Limited Warranty & Spares for 12 Months (details on next page)

• The Fuel Gas processing system shall be PIONEER Model DCR---

• Single point fuel gas inlet, outlet and drain connections within 6” of edge of equipment

• The Fuel Gas processing system shall be PIONEER Model DCR---

Five Year Limited Warranty PIONEER systems are warranted to be free from defects in material and workmanship for a period of one year from the date of installation, or up to 18 months from the date of shipment, whichever comes first, provided the equipment is installed and used according to the company’s recommendation. The company’s liability is limited to the repair, refund, or replacement in kind at the company’s sole option. In no event will the company be liable or responsible for incidental and consequential damages, even if the possibility of such has been made known to the company. Normal maintenance items are excluded. Key components, heat exchangers & refrigerant compressors carry a five-year pro-rated warranty.

Pioneer Air Systems - Specializing in Air, Water & Gas Processes Since 1980

SPARES & CONSUMABLES i.e. filter elements etc. required for 12 months of operation.