HomeMy WebLinkAboutAtmautluak Washeteria Heat Recovery Study - Aug 2011 - REF Grant 7060935ATMAUTLUAK, ALASKA
HEAT RECOVERY STUDY
PREPARED FOR:
ALASKA ENERGY AUTHORITY
Project: AEA10-029, 2010 Waste Heat Recovery
PREPARED BY:
Alaska Energy and Engineering, Inc.Mailing Address - P.O. Box 111405 Anchorage, AK 99511-1405
(907) 349-0100, 349-8001 FAX
August 22, 2011
AEA- Atmautluak Heat Recovery Analysis August 2011
Alaska Energy and Engineering
Page 1 of 5
EXECUTIVE SUMMARY
Four community facilities in Atmautluak were evaluated for heat recovery potential.
Based on the heat available, only the Washeteria is proposed to receive recovered
heat at this time. Total estimated annual heating fuel use of the Washeteria is
approximately 4800-gallons. Estimated fuel savings realized by implementing a heat
recovery system is 4,395-gallons. The estimated cost for the heat recovery project is
$338,578. The simple payback based on a fuel cost of $ 6.36 per gallon is 12.1 years.
1.0 INTRODUCTION
Alaska Energy and Engineering, Inc. was retained by the Alaska Energy Authority
(AEA) to review the feasibility of providing available recovered heat from the existing
Atmautluak Joint Utilities power plant to adjacent community buildings in Atmautluak,
and provide a budgetary project cost estimate based on Force Account Construction,
including Design Engineering and Construction Administration.
Currently there is not a heat recovery system in Atmautluak. Considered buildings are
located together between 350 and 550 feet from the power plant, with the Washeteria
being the furthest building. Arctic piping would be routed at grade alongside the
existing sewer outfall utilidor. The existing utilidor is in poor condition and is not
adequate to support the heat recovery piping.
Additional assumptions have been made in the development of this report including
but not limited to the proposed arctic piping route, building heating loads, and flow
rates and pressure drops of the existing power plant cooling system. It is anticipated
that refinements in arctic pipe size and routing, pump and heat exchanger sizing, and
other design elements will be required as the project progresses to final design.
Available as-built information was obtained from AEA, regarding the existing
generation equipment and power plant heat loads. End-user annual fuel use was also
obtained from The Village of Atmautluak and Atmautluak Limited Corporation. A site
visit was conducted June 2 and 3, 2011.
2.0 OVERVIEW
The purpose of this study is to provide an estimate of the heat that can be recovered
from the jacket water of the Atmautluak Joint Utilities power plant diesel engines and
used to offset heating oil consumption at the nearby public buildings. Useable
recovered heat is quantified in gallons of heating fuel saved using a gross heating
value of 134,000 BTU per gallon of #1 arctic diesel fuel and an overall efficiency of
75% for boilers and 85% for Toyo Laser direct vent stoves.
Buildings evaluated for recovered heat include the Washeteria, Community Hall, Bingo
Hall, and Store. The estimated average annual heating fuel consumption for the four
end-user buildings totals 9447-gallons: Washeteria is 4800-gallons, Community Hall is
2000-gallons, Bingo Hall is 667-gallons, and the Limited Store is 1980-gallons. The
available recovered heat is limited to about 5800-gallons of fuel savings.
During the site visit, the village identified the Washeteria as the preferred building to
receive recovered heat. Due to the high capital cost to connect a building to the heat
recovery system, and because the Washeteria utilizes nearly all the available
recovered heat, this report only includes the Washeteria.
The Washeteria foundation has experienced noticeable pile jacking. ANTHC is
currently developing a project to stabilize and level the foundation.
AEA- Atmautluak Heat Recovery Analysis August 2011
Alaska Energy and Engineering
Page 2 of 5
3.0 ESTIMATED RECOVERED HEAT UTILIZATION
A heat recovery utilization spreadsheet has been developed to estimate the
recoverable heat based on monthly total electric power production, engine heat rates,
building heating demand, heating degree days, passive losses for power plant heat
and piping, and arctic piping losses. The spreadsheet utilizes assumed time-of-day
variations for electric power production and heat demand. Power Cost Equalization
(PCE) data for fiscal years 2008, 2009, and 2010 were averaged and used in the
spreadsheet. The estimated heat rejection rate for the lead power plant genset, a John
Deere 6081HF070 1800-rpm genset, is used to estimate available recovered heat.
Heating degree-days for Bethel were utilized for this site. All arctic piping is assumed
to be routed at grade supported on timber sleepers. All exterior power plant hydronic
piping is 3” pipe with 1” of fiberglass insulation. Information collected from power plant
renovations in 2009 were used to estimate the heating load for the power plant.
The spreadsheet uses monthly heating degree-days to distribute annual fuel
consumption by month. The monthly heat load is then allocated by hour of day using
an estimated daily temperature variation (diurnal cycle). The end-user hourly heat
load is compared to the hourly available heat from the power plant, less power plant
heating loads and parasitic piping losses, and the net delivered heat to the end-user is
determined.
Following is a summary of annual fuel use and estimated heat utilization in equivalent
gallons of fuel for the Washeteria:
Facility Estimated Annual
Fuel Use (Gallons)
Estimated Heat *
Delivered (Gallons)
Washeteria 4800 4395
* Does not account for peak DHW loads
Consideration was given to repowering one of the John Deere 6081’s with a marine
jacketed engine. However, while the marine jacket significantly increases the available
recovered heat from the engine, the increase in recovered heat does not offset the
reduced fuel economy of a marine engine, so this option was dismissed.
4.0 HEAT RECOVERY SYSTEM DESCRIPTION AND OPERATION:
A heat recovery system captures jacket water heat generated by Atmautluak Joint
Utilities power plant that is currently rejected to the atmosphere. The recovered heat
will be transferred via above grade arctic piping to the Washeteria. The objective is to
reduce the consumption of expensive heating fuel by utilizing available recovered heat.
Although heat recovery is an excellent method of reducing heating fuel costs,
recovered heat is a supplementary heat source and it is imperative that the end-
user facility heating systems are operational at all times.
Hot engine coolant is piped through a plate heat exchanger located at the power plant.
Heat is transferred from the engine coolant to the recovered heat loop without mixing
the fluids. The recovered heat fluid is pumped through arctic pipe to the end-user and
is tied into the end-user heating system using a plate heat exchanger.
AEA- Atmautluak Heat Recovery Analysis August 2011
Alaska Energy and Engineering
Page 3 of 5
4.1 Atmautluak Joint Utilities Plant Tie-in
Modifications to the Atmautluak Joint Utilities power plant cooling system include
installation of a power plant heat exchanger, district heating loop pump, a new
expansion tank and new instrumentation.
All cooling system piping will be insulated with a minimum of 1” insulation and have an
aluminum jacket where exposed to the weather. All valves will be either bronze ball
valves, or lug style butterfly valves with seals compatible with 50/50 glycol/water
mixtures at 200°F. Air vents, thermometers, pressure gauges, drain valves and
pressure relief valves will also be provided.
4.2 Arctic Piping (Recovered Heat Loop)
Due to the permafrost soils in Atmautluak, the proposed arctic piping is a pre-insulated
arctic piping system routed above grade. The piping will be routed from the Atmautluak
Joint Utilities plant to the Washeteria within existing rights-of-ways and on Atmautluak
LTD property. The piping will exit the power plant adjacent to the radiators, run
alongside the power plant foundation, and follow the existing boardwalk from the
power plant to the sewer utilidor. The piping will then run adjacent to the existing
utilidor to the Washeteria. Where necessary, 4-wheeler and snowmobile crossings will
be built to protect the piping and allow travel across the piping.
The arctic piping system is a pre-insulated, bonded steel piping system. The pipes
consist of SCH40 carrier pipe and HDPE outer jacket bonded to polyurethane foam
insulation. The carrier piping joints will be welded. The system comes complete with
all fittings, tools and accessories required for assembly. The recovered heat fluid will
be a 50/50 Propylene Glycol/Water solution to provide freeze protection to the piping.
4.3 End-User Building Tie-ins
End-user building tie-ins typically consist of either brazed plate heat exchangers or
cabinet unit heaters. A plate heat exchanger located in the Washeteria mechanical
room will be tied into the boiler return piping to pre-heat the boiler water. The
maximum anticipated delivered recovered heat supply temperature is about 180°F.
When there is insufficient recovered heat to meet the Washeteria heating load, the
boiler will fire and add heat.
Typical piping will be type L copper tube with solder joints. Isolation valves will be
solder end bronze ball valves or flanged butterfly valves. All piping will be insulated
with a minimum of 1” insulation with an all-service jacket. Flexibility will be provided
where required for thermal expansion and differential movement. Air vents,
thermometers, pressure gauges, drain valves and pressure relief valves will also be
provided.
4.4 Rights-of-Way Issues
There does not appear to be any conflicts with rights-of-ways for the arctic piping
between the power plant and Washeteria, as the route is expected to be within existing
rights-of-ways and Atmautluak Limited property.
AEA- Atmautluak Heat Recovery Analysis August 2011
Alaska Energy and Engineering
Page 4 of 5
A Heat Sales/Right-of-Entry Agreement will be required between Atmautluak Joint
Utilities and the Washeteria to define the parties’ responsibilities, the cost of recovered
heat, and to authorize the installation and operation of the heat recovery equipment.
5.0 PRELIMINARY EQUIPMENT SELECTIONS
The following initial equipment selections are sized and selected based on preliminary
data and will require minor modifications to reflect final design.
5.1 Heat Exchangers
Based on initial selected flow rates, brazed plate heat exchangers appear to be
suitable for all locations. Fluid in the power plant cooling system is assumed to be
50% Ethylene Glycol, all other loops assumed to be 50% Propylene Glycol. Initial heat
exchanger selections are as follows.
HX-1: Power Plant 200 MBH capacity
Primary: 34 GPM 190 F° EWT, 2.0 PSI max WPD, 20°dT
Secondary: 24 GPM 180 F° LWT, 1.5 PSI max WPD, 15°dT
HX-2: Washeteria 165 MBH capacity
Primary: 24 GPM 180 F° EWT, 1.0 PSI max WPD, 15°dT
Secondary: 39 GPM 175 F° LWT, 2.0 PSI max WPD, 15°dT
5.2 Arctic Piping
The heat recovery loop from the power plant to the Washeteria is approximately 1100-
feet (round trip). The arctic piping utilizes 2” SCH40 steel preinsulated arctic piping to
minimize pressure drop and reduce pumping energy. The piping will be routed above
grade alongside the existing sewage utilidor.
5.3 Circulating Pumps
This pump will be located in the power plant and will circulate 50/50 propylene glycol to
the end users. The pump is not sized to meet the peak Washeteria heat load, only the
estimated available recovered heat.
P-HR1: Glycol circulation loop within power plant
Flow = 24 GPM, Head = 32’
Initial Selection: Grundfos UPS 32-80/2, 24 GPM at 32’ TDH, 1/2 HP
5.4 Expansion Tank
Total heat recovery loop volume required to supply heat to the Washeteria is
approximately 200-gallons. Pressure relief at the power plant heat exchanger will be
50 PSIG and the maximum normal operating pressure will be 90% of maximum (45
PSIG).
ET-1: System requirements: 23-gallon tank and 14.1 gallon acceptance
Select: Extrol AX-80V, 44.5-gallon tank and 22.6-gallon acceptance
AEA- Atmautluak Heat Recovery Analysis August 2011
Alaska Energy and Engineering
Page 5 of 5
6.0 CONCLUSIONS AND RECOMMENDATIONS
There is sufficient recovered heat available to only heat the community Washeteria.
Estimated construction costs were determined based on prior recent heat recovery
project experience, and include materials, equipment, freight, labor, design,
construction management, and startup and testing. All work at the power plant and
Washeteria, and design and construction management/administration for the complete
project is included (refer to attached cost estimate).
The estimated project cost for the Washeteria only is $338,578. Estimated fuel savings
are 4,395-gallons. Using an assumed fuel price of $6.36/gallon results in estimated
savings of $27,952 annually, for a simple payback of 12.1 years.
8/22/2011 ATMU - HR MASTER CALC-8-22-11.xls Page 1 of 4RECOVERED HEAT UTILIZATION SIMULATION WORK SHEET.Date: August 2011Location:AtmautluakEst. Annual Fuel Savings (Gallons):Fuel heat value:134000Btu/gal(based on #1 arctic diesel fuel)GENSET DATA - SEE NOTE 3SYSTEM LOSS DATA:Heat rate at kw-load above0 1349Btu/kwh Constant losses:Heat rate at kw-load above26 1349Btu/kwh Plant piping:1218Btu/hr.60' of 3" insulated carbon pipe Heat rate at kw-load above52 1349Btu/kwh Arcticpiping:0Btu/hr.See Exterior Piping belowHeat rate at kw-load above78 1349Btu/kwh Genset Eng. Preheat:3412Btu/hr.Assume 1 kW lost for enginepre-heatHeat rate at kw-load above104 1349Btu/kwhTotal constant:4630Btu/hr.Heat rate at kw-load above131 1349Btu/kwh Heat rate at kw-load above157 1349Btu/kwh Variable losses:Heat rate at kw-load above183 1349Btu/kwh Exterior piping:162Btu/hr.xF1100LF 2" steel AP @ 0.14 BTU/Hr-ft-F & 60' Hydronic Pipe@ 0.133 BTU/Hr-ft-FHeat rate at kw-load above209 1349Btu/kwh Plant heating:0Btu/hr.xFAssume heat from generators keepsplant warmHeat rate at kw-load above235 1349Btu/kwh Radiator losses:50Btu/hr.xFEstimate based on 2 exterior radiatorsHeat rate at kw-load above261 1349Btu/kwh GENERATION DATA:WEATHER DATA: PCE Data - See Note 1Kwh/month:HDD/Month: BethelMonth kWh Gen Fuel UsedJanuary65712 1832 July48142 3986NOTES:February60387 1602August43843 39391) kWH Generated & Fuel Used Based on average of PCEFY07, FY08 and FY09Data.March 67233 1609 September54601 39722) Not UsedApril 58394 1194 October53398 43013) Heat rate of 1349 Btu/kWh for JD 6081HF070 1800 rpmMay56472 742 November55779 4408June 54588 406 December61959 5420July48142 299 January65712 5140August43843 367 February60387 4885September54601 589 March67233 5043October53398 1083April58394 4482November55779 1425 May56472 4505December61959 1777 June54588 4337Total: 680,508 Total: 12925 Total: 680508 54420BUILDING DATA:Fuel use, Non- Boilerest'dgal'sgallonsSeasonalSeasonalEfficiencysaved Building in use, 1=yes, 0=noOper. Oper. JanuaryFebruary March April May June July AugustSeptemberOctoberNovemberDecemberMonths HDDWasheteria3800 1000 75% 4395 1 1 1 1 1 1 1 1 1 1 1 11212926Lim Store0 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 11212926Com Hall0 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 11212926Bingo Hall0 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 112129260 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 112129260 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 112129260 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 112129260 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 112129260 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 112129260 0 75% 0 1 1 1 1 1 1 1 1 1 1 1 11212926Total 3800 1000 4800 43954,395
0100200300400500600700Heating Fuel Equivalent (Gallons per Month)Atmautluak Estimated Recovered Heat UtilizationRecovered Heat AvailableTotal Heat DemandRecovered Heat Delivered
0100200300400500600700Gallon #1 Heating FuelATMAUTLUAK RECOVERED HEAT405 Gal Boiler Heat4395 Gal Recovered Heat
ALASKA ENERGY AND ENGINEERINGAEA - ATMAUTLUAK HEAT RECOVERY PROJECTFORCE ACCOUNT CONSTRUCTION COST ESTIMATE8/22/2011SITE & EXTERIOR WORK $76,705POWERPLANT ADDITIONS $43,083WASHETERIA $40,500OVERHEAD $26,154MISCELLANEOUS $13,500FREIGHT $34,707CONSTRUCTION SUB-TOTAL $234,649DESIGN AND CONSTRUCTION ADMIN. $25,000CONSTRUCTION MANAGEMENT $20,000PROJECT SUB-TOTAL $279,649CONTINGENCY @ 20% $56,430TOTAL PROJECT COST $336,078MATCH$0TOTAL GRANT FUNDS REQUESTED$338,578A-1 of 3
ALASKA ENERGY AND ENGINEERINGAEA - ATMAUTLUAK HEAT RECOVERY PROJECTFORCE ACCOUNT CONSTRUCTION COST ESTIMATE8/22/2011ITEM QUAN UNIT UNIT MATL UNIT LAB LAB LABOR CONTR FREIGHT TOTAL UNIT TOTALCOST COST HRS HRS RATE COST COST COST COST WT WT(#)SITE & EXTERIOR WORK6x6 Heavy Timber Sleepers320 lin.ft. $3.00 $960 0.10 32 $85 $2,720 $3,680 10.00 3200Prop Glycol (50/50 - 55-gal drum)5 ea. $650.00 $3,250 0 0 $85 $0 $3,250 520.0 2600Boardwalk Repair/Construction1 lump $2,000.00 $2,000 50 50 $85 $4,250 $6,250 1000.0 1000Groundwork / Grading0 lin.ft. $0.00 $0 0 0 $85 $0 $0 02" Steel Artic Pipe1100 lin.ft. $45.00 $49,500 0.15 165 $85 $14,025 $63,525 6.0 6600Artic Pipe Fittings1 lump $2,500 $2,500 0 $85 $0 $2,500 1000.0 1000POWERPLANT ADDITIONSPlate HXR, (200 MBh @ 15F)1 ea. $2,000 $2,000 10 10 $85 $850 $2,850 200.0 2002" Copper Pipe60 lin.ft. $41.60 $2,496 0.15 9 $85 $765 $3,261 4.36 262Electrical (Misc) 1 ea. $2,000 $2,000 40 40 $85 $3,400 $5,400 500.0 500Pipe/Valves/Ftgs/Gauges 1 lump $7,000 $7,000 100 100 $85 $8,500 $15,500 1500.0 1500Circ Pump (Grundfos - 24gpm @ 32') 2 ea. $1,350 $2,700 20 40 $85 $3,400 $6,100 45.0 90Misc Strut / Pipe Hangers/ Hardware 1 lump $2,000 $2,000 40 40 $85 $3,400 $5,400 500.0 500Expansion Tank (AX-40V) 1 ea. $672 $672 20 20 $85 $1,700 $2,372 96.0 96Misc. Controls 1 lump $500 $500 20 20 $85 $1,700 $2,200 200.0 200WASHETERIAPlate HXR, (165 MBh @ 15F)1 ea. $2,000 $2,000 10 10 $85 $850 $2,850 200.0 200Electrical (Misc) 1 ea. $2,000 $2,000 40 40 $85 $3,400 $5,400 500.0 500Temp Control Device 1 ea. $1,500 $1,500 10 10 $85 $850 $2,350 10.0 10Pipe/Valves/Ftgs/Gauges 1 lump $7,000 $7,000 60 60 $85 $5,100 $12,100 1500.0 1500Misc Strut / Pipe Hangers/ Hardware 1 lump $2,000 $2,000 40 40 $85 $3,400 $5,400 500.0 500BTU meter 1 ea. $8,500 $8,500 20 20 $85 $1,700 $10,200 50.0 50Misc. Controls 1 lump $500 $500 20 20 $85 $1,700 $2,200 200.0 200MISCELLANEOUSMisc Hardware 1 lump $5,000 $5,000 0 0 $85 $0 $5,000 499.0 499Misc Hardware 1 lump $2,500 $2,500 0 0 $85 $0 $2,500 500.0 500Misc Tools & Safety Gear 1 lump $4,000 $4,000 0 0 $85 $0 $4,000 1500.0 1500Consumables, Gases, Etc. 1 lump $2,000 $2,000 0 0 $85 $0 $2,000 1500.0 1500A-2 of 3
ALASKA ENERGY AND ENGINEERINGAEA - ATMAUTLUAK HEAT RECOVERY PROJECTFORCE ACCOUNT CONSTRUCTION COST ESTIMATE8/22/2011ITEM QUAN UNIT UNIT MATL UNIT LAB LAB LABOR CONTR FREIGHT TOTAL UNIT TOTALCOST COST HRS HRS RATE COST COST COST COST WT WT(#)OVERHEADROW Legal Work 1 lump $2,000 $2,000 0Rent Heavy Equip 1 lump $2,500 $2,500 0Misc Tool Rent 1 lump $5,000 $5,000 0Commission System & Training 20 hr 1 20 $95 $1,900 $1,900 0Superintendent Overhd Off-Site 40 hr 1 40 $95 $3,800 $3,800 0Superintendent Overhd On-Site 40 hr 1 40 $95 $3,800 $3,800 0Crew Travel Time 12 hr 1 12 $95 $1,140 $1,140 0Crew Airfares 2 trips $1,000 $2,000 $2,000 0Crew Per Diem 42 mn.dy. $60 $2,514 $2,514 0Housing Rent 1 mo. $1,500 $1,500 $1,500 0FREIGHT24,707Freight24707lb. $1.00 $24,707Air Freight Tool Mob & Demob 2 lump $2,500 $5,000Misc Small Freight & Gold Streaks 1 lump $5,000 $5,000CONSTRUCTION SUB-TOTAL $114,578 838 $72,350 $15,514 $34,707 $237,149Engineering (Design & CCA) 1 lump $25,000Construction Management1 lump $20,000PROJECT SUB-TOTAL $114,578 $72,350 60,514$ $34,707 $282,149Contingency 20 % $56,430CONSTRUCTION TOTAL $338,578Match: $0Renewable Energy Fund Grant Amount: $338,578difference ($338,578)A-3 of 3