Optimize Your Boilers. Kevin Brady Merlo Energy

Transcription

1 Optimize Your Boilers Kevin Brady Merlo Energy

2 U.S. Energy Consumption by Fuel ( ) in Quadrillion British Thermal Units (BTU) Natural gas demand is expected steadily increase through 2015

3 U.S. Energy Production by Fuel ( )

4 Energy Demand Is Outpacing Production of All Sources Trended out 7-8% increase in consumption per year

5 METER METER METER METER

6 $perccf - NYMEX Natural Gas Prices Are Volatile Example of price swings - Daily price for January 2007 $1.40 $1.30 High =$1.27 January's Daily Price $1.20 $1.10 $1.00 Over time, the price for January 2007 has changed by over 50% $0.90 $0.80 Diff. =$0.68 (53%) $0.70 $0.60 Low =$0.59 $0.50 Days

7 The BIG Question is: When is the best time to buy natural gas? Factors That Influence Prices Monthly Cost of Gas $9.00 Cost per MMBtu $8.50 $8.00 $7.50 April 1st, starts the Storage Injection Season Filling Storage Apr. - Oct. Storage must be filled by October 31st If storage is getting to full, prices can drop Electric Demand Hurricane Season Anticipation of Colderthan-Normal Weather & Storage Levels If storage looks good and weather is mild, prices tend to drop. If not, prices will continue to rise $7.00

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9 Cost of Steam Via Cost of Natural Gas Fuel Type Gas Boiler Output 350 Hp Gas Cost/Decatherm 8.67 Annual Hours 8700 Steam Output 12,075 lbs/hr Boiler Efficiency 77% 80% Max Gas Burn Rate therm/hr therm/hr Steam Cost/1000lbs $10.92 $10.51 Annual Cost $1,147, $1,104, What can you capture? $43, or 3.75%

10 Natural Gas Increase to $10.00/Decatherm Fuel Type Gas Boiler Output 350 Hp Gas Cost/Decatherm $8.67 $10.00 Annual Hours 8700 Steam Output 12,075 lbs/hr Boiler Efficiency 77% 77% Max Gas Burn Rate therm/hr therm/hr Steam Cost/1000lbs $10.92 $12.60 Annual Cost $1,147, $1,323, What can you expect? $176, or 13.3% increase

11 METER METER METER METER

12 Baseline Boiler 350 Horsepower Running Load 10,000 Lbs/hr 125# Running Pressure 4380 Hrs (1/2 Year) Efficiency 80% Feedwater 180 Deg. F Return $10.00/MMBTU Gas Cost $.002/gallon Sewage Cost $.002/gallon Treatment Cost 60 Deg. F Initial Water Temp.

13 Case for Trap Replacement Energy Dollars Lost for (1) Failed Trap W=24.24 * Pa * D 2 Pa= Pgage + Patmosphere D 2 = Diameter of orifice squared W= lbs/hr lost 24.24*139.7* lbs/hr Lost Q= (W * H * L * 10-6 * C)/BE H= Hours in heating season L= Latent heat of Pa 10-6 = MMBTU/BTU C= Cost of gas per MMBTU BE= Boiler efficiency Q= (52.91*4380*869*10-6 *10)/.80 $2, Loss

14 Case for Insulation Energy Dollars Lost per 100 ft of 4 Pipe 4 Un-insulated line yields a Heat Loss of: 850 MMBTU/yr loss per 100 pipe $10/MMBTU*850 MMBTU/Yr = $8,500 per Year 90% Efficient insulation:.90 * $8,500.00/yr = $7, Annual Savings

15 Improving Fuel to Steam Eficiency hrs (1/2 $1/therm 80% efficiency = $641,670 gas cost per year 1% increase in fuel-to-steam efficiency would save $7884 per year in gas cost alone ($641,670 - $633,786 = $7884)

16 Case for Fuel-to-Air Trim Excess air of 44.9% and O 2 of 7% with a stack temp of 400 deg F yields combustion efficiency of 78.2% Excess air of 15% and O 2 of 3% with a stack temp of 400 deg F yields combustion efficiency of 80.4% 42 BTU input of fuel per Boiler Hp (350 Hp * 42 = 14,700 BTU/lb) 14,700 BTU/lb * 4380 hrs = 64,386,000 BTU consumption Savings = fuel consumption * (1 efficiency1/efficiency2) * fuel cost per MMBTU = 64,386 MMBTU *.027 * $10/MMBTU = $17, annually for ½ year operation 1% Efficiency gain Savings = 64,386 MMBTU *.01 * $10/MMBTU = $6, annually for ½ year operation

17 Case for Economizer Boiler Thermal Output = lbs/hr running output * (latent pressure boiler feedwatertemp) = 10,000 * ( ) = 10,450,000 BTU/hr Recoverable heat from chart is 650,000 BTU/hr based on 400 Deg. F stack temperature with economizer bringing stack temperature down to 250 Deg. F Savings = Recoverable heat (MMBTU) * Cost of fuel/mmbtu * hrs of operation =.65 MMBTU/hr * $10.00/MMBTU * 4380 hrs/year = $28, ½ year operation = $52, yearly hours

18 METER METER METER METER

19 Case for Returning More Condensate Dumping 10% of condensate load to drain = 1000 lbs/hr Delta T = condensate return temp. make-up water temp ( = 125 Deg F) Sewage cost of $.002/gallon Treatment cost of $.002/gallon Sewage/Chemical Savings = (condensate load * yearly hrs * dumping cost)/density of H2O = (1,000 lbs/hr * 4380 hrs * $.004)/8.34 lbs/gal = $2, ½ year operation Fuel Savings = (condensate load * yearly hrs * Delta T * fuel cost)/boiler efficiency = (1000 lbs/hr * 4380 hrs * 125 Deg F * $.00001/BTU)/.80 = $ ½ year operation

20 Case for Minimizing Blowdown Decreasing blowdown rate from 8% to 6% Feedwater loss = Initial Final Initial = 10,000 lbs/hr/(1-.08) = 10,870 lbs/hr Final = 10,000 lbs/hr/(1-.06) = 10,638 lbs/hr Make-up water savings = Initial Final = 232 lbs/hr Thermal Energy Savings = Enthalpy of boiler feedwater Enthalpy of make-up = = 297 BTU/lb Annual Fuel Savings = (Water savings * yearly hours * Thermal savings * Cost of Gas)/ (Boiler Efficiency * 10 6 ) = (232lbs/hr * 4380hrs/yr * 297 BTU/lb * $10.00/MMBTU)/.80 * 10 6 = $3, ½ year operation Annual Water & Chem.= (Water savings * yearly hours * sewer & chem costs)/weight H2O = (232 lbs/hr * 4380 hrs/yr * $.004/gallon) / 8.34 lbs/gallon = $ ½ year operation

21 METER METER METER METER

22 Case for Recovery Heat from Boiler Blowdown Assumption that customer utilizes continuous blowdown of 6% of operating load 6% blowdown rate has 1.7 MMBTU/hr recoverable heat on 100,000 lbs/hr w/ 90% recovery Annual Energy Savings = (Recoverable heat * (operating load/100,000 lbs/hr baseline) * yearly hours) / efficiency of boiler = (1.7 MMBTU/hr * (10,000 / 100,000 lbs/hr) * 4380 hours/year) /.80 = MMBTU ½ year operation Annual Cost Savings = MMBTU/year * $10/MMBTU = $ ½ year operation

23 Case for Scale Treatment Annual operating cost w/scale = MMBTU/yr * $/MMBTU Gas * % loss per scale thickness 1/32 inch scale thickness = 2% fuel loss Loss = 64,386 MMBTU/yr * $10.00/MMBTU *.02 = $12, savings by proper scale treatment

24 Combustion Air 15% excess air is expected and designed around Increase of air temperature to 100 deg F decreases the excess air by 36% This means less BTU loss through stack and ultimately less gas usage With a gas meter, you can document the savings and justify your boiler adjustments

25 METER METER METER METER

26 What Can We Gain From This? 1 Trap 100 Insulation F-A Efficiencies Economizer Return Condensate Minimize Blow-down Heat Rec. Blow-down Scale ½ Year Savings $2, $3, $17, $28, $8, $4, $9, $6, Total $81, Year Savings $5, $7, $34, $52, $17, $9, $18, $12, Total $157,887.00

27 Accuracy 1% vs 1-1/2% Devices 1% +/- 120 lb/hr 1-1/2% +/- 180 lb/hr 33 % Variance 262,800 lb/yr Steam Not Accounted For Why Look at Efficiencies if you compromise Meter Accuracy? Comparison based on 12,000 lb/hr boiler

28 Turndown on 12,000 lb/hr Vortex Meter vs Orifice Plate Vortex Meter 15:1 800 lb/hr low end Orifice Plate 3: lb.hr low end Vortex Meter has a 5 times greater turndown Why look at efficiencies if you compromise on meter turndown?

29 Where Do I Start? Meter Your Usage (Fuel in & Steam Out) Steam Trap Audit (Including Insulation) Air-to-fuel Efficiency (Parallel Positioning) Fuel-to-steam Efficiency (Excess O2) Stack Temperature (Economizer) Boiler Feed Temperature (Blow-down Recovery)

30 Benchmarking & Validation of Energy Savings Kevin Brady Merlo Energy