Optimize Your Boilers Kevin Brady Merlo Energy
U.S. Energy Consumption by Fuel (1980-2030) in Quadrillion British Thermal Units (BTU) Natural gas demand is expected steadily increase through 2015
U.S. Energy Production by Fuel (1980 2030)
Energy Demand Is Outpacing Production of All Sources Trended out 7-8% increase in consumption per year
METER METER METER METER
$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
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
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 152.14 therm/hr 146.44 therm/hr Steam Cost/1000lbs $10.92 $10.51 Annual Cost $1,147,618.00 $1,104,582.00 What can you capture? $43,036.00 or 3.75%
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 152.14 therm/hr 152.14 therm/hr Steam Cost/1000lbs $10.92 $12.60 Annual Cost $1,147,618.00 $1,323,665.00 What can you expect? $176,047.00 or 13.3% increase
METER METER METER METER
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.
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*.015625 52.91 lbs/hr Lost Q= (W * H * L * 10-6 * C)/BE H= Hours in heating season L= Latent heat of steam @ Pa 10-6 = MMBTU/BTU C= Cost of gas per MMBTU BE= Boiler efficiency Q= (52.91*4380*869*10-6 *10)/.80 $2,517.34 Loss
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 = $7,650.00 Annual Savings
Improving Fuel to Steam Eficiency 350 Hp @ 4380 hrs (1/2 yr) @ $1/therm ($10/decatherm) @ 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)
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, 384.00 annually for ½ year operation 1% Efficiency gain Savings = 64,386 MMBTU *.01 * $10/MMBTU = $6,438.60 annually for ½ year operation
Case for Economizer Boiler Thermal Output = lbs/hr running output * (latent heat @ pressure boiler feedwatertemp) = 10,000 * (1193 180) = 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 = $28,470.00 ½ year operation = $52,000.00 8000 yearly hours
METER METER METER METER
Case for Returning More Condensate Dumping 10% of condensate load to drain = 1000 lbs/hr Delta T = condensate return temp. make-up water temp (180 60 = 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 = $2,100.72 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 = $6843.75 ½ year operation
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 = 325 28 = 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 = $3,772.50 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 = $487.37 ½ year operation
METER METER METER METER
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 = 930.75 MMBTU ½ year operation Annual Cost Savings = 930.75 MMBTU/year * $10/MMBTU = $9307.50 ½ year operation
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 = $12,877.00 savings by proper scale treatment
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
METER METER METER METER
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 $2,517.00 $3,825.00 $17,384.00 $28,470.00 $8,943.00 $4,529.00 $9,307.00 $6,439.00 Total $81,414.00 1 Year Savings $5,034.00 $7,650.00 $34,768.00 $52,000.00 $17,886.00 $9,058.00 $18,614.00 $12,877.00 Total $157,887.00
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
Turndown on 12,000 lb/hr Vortex Meter vs Orifice Plate Vortex Meter 15:1 800 lb/hr low end Orifice Plate 3:1 4000 lb.hr low end Vortex Meter has a 5 times greater turndown Why look at efficiencies if you compromise on meter turndown?
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)
Benchmarking & Validation of Energy Savings Kevin Brady Merlo Energy