RFQ Toolbox Nicky Byer, Applications Engineer nicky.byer@munters.com Dan McClung, Applications Engineer dan.mcclung@munters.com September 29, 2012

Heat Recovery: Knowing what to ask Hot side inlet temperature (operating/design) Cold side inlet temperature Required performance: effectiveness, cold outlet, or hot outlet Pressure drop requirements Gas composition / humidity ratio Max differential pressure Specific material requirements Size limitations / flow arrangement Corrosives (chlorine, sulfur, etc.) Particulates Condensables Accessories (access doors, water wash, sonic horn, etc.) Payback information ($/MMBTU and $/kWh) RFQ Toolbox September 29, 2012

Filling Out the Heat Exchanger Questionnaire Request for Quotation Filling Out the Heat Exchanger Questionnaire RFQ Toolbox September 29, 2012

RFQ Toolbox September 29, 2012

RFQ Toolbox September 29, 2012

Cost of heat exchanger X2 RFQ Toolbox September 29, 2012

Major Factors that affect Heat Exchanger Unit Cost Airstream Properties Temperature Corrosives, Particulates, etc. Max pressure differential Effectiveness Size Limitations Allowable Pressure Drop (DP) –CRITICAL RFQ Toolbox September 29, 2012

Pressure Drop Example Customer wants to use the exhaust stream from a 10,000 SCFM incinerator with outlet temperature of 1000°F to preheat a makeup airstream at 70°F. Heat Exchanger Specification: 304 SS Construction, UI flow pattern, 70% Effective, Fully Insulated unit with Expansion Joints If unit has 1.5” W.C. DP per side, Total 3” W.C. DP then: 94 46 78 Unit Cost = $92,255 NET If unit has 3” W.C. DP per side, Total 6” W.C. DP then: 94 46 56 Unit Cost = $74,191 NET Additional Unit Cost for Lower DP = $18,064 (~20%) RFQ Toolbox September 29, 2012

RULES OF THUMB Converting ACFM and SCFM SCFM=ACFM * [530/(460+T)] ACFM=SCFM * [(460+T)/530] RFQ Toolbox September 29, 2012

RULES OF THUMB Converting #/Hr to SCFM (#/Hr.) / 4.5 = SCFM * 4.5 = 0.075 (Density of Standard Air, #/Cubic Foot) * 60 Min./Hr. RFQ Toolbox September 29, 2012

RULES OF THUMB Converting Temperature Celsius to Fahrenheit °F= 1.8 X °C + 32 Fahrenheit to Celsius °C= (°F - 32)/ 1.8 RFQ Toolbox September 18, 2018

RULES OF THUMB Converting Pressure psig to psia Psig + 14.7 psia to psig Psig – 14.7 psig to inches of H20 Psig X 27.7 inches of H20 to psig inches of H20/ 27.7 RFQ Toolbox September 18, 2018

RULES OF THUMB tho tci thi tco RFQ Toolbox September 18, 2018

RULES OF THUMB Stacks Measure free flow area Measure velocity with flow meter Measure temperature with IR gun or TC Calculate BTU’s available RFQ Toolbox September 18, 2018

RULES OF THUMB Energy Available in Exhaust BTU/Hr = Mass Flow * Cp * DT or BTU/Hr = 1.08 *SCFM* DT DT = Desired Exhaust Temperature change Mass Flow = #/Hr Cp = Average Specific Heat SCFM = Standard Cubic Feet per Minute RFQ Toolbox September 18, 2018

RULES OF THUMB Stacks Rule of thumb is 1000 FPM minimum velocity Higher velocities are often seen on stacks with fumes for dilution such as from exhaust hoods or oxidizers Max is typically in the 2500-3000 FPM range RFQ Toolbox September 18, 2018

Prices this year are the lowest they have been in the past 10 years. RULES OF THUMB Natural Gas Prices Good Internet Source: http://www.eia.gov/naturalgas/weekly/ Prices this year are the lowest they have been in the past 10 years. RFQ Toolbox September 18, 2018

Fuel costs are currently approximately $5.00/MMBTU RULES OF THUMB 1 Therm = 100,000 BTU's. $5/MMBTU’s = $0.50/Therm Fuel costs are currently approximately $5.00/MMBTU RFQ Toolbox September 18, 2018

Equipment Cost / Yearly Savings = Simple Payback RULES OF THUMB Simple Payback Yearly Savings = MMBTU/hr Saved * Yearly hours of Op * Cost of Fuel ($/MMBTU) Equipment Cost / Yearly Savings = Simple Payback RFQ Toolbox September 18, 2018

Stoichiometric Combustion Process RULES OF THUMB Stoichiometric Combustion Process This relates to the ratio of natural gas to air for a combustion process. Standard is 10 parts air to 1 part gas assuming the system DOES NOT run with excess air. RFQ Toolbox September 18, 2018

Stoichiometric Combustion Process RULES OF THUMB Stoichiometric Combustion Process If you have an exhaust from a gas fired oven and you know the gas usage then you can estimate the stack flow rate for quick energy savings calculations. This only works for 10:1 air to gas ratios. You will have to adjust if it is running with excess air. RFQ Toolbox September 18, 2018

Stoichiometric Combustion Process RULES OF THUMB Stoichiometric Combustion Process If oven gas usage is 3 MM BTU’s /Hr then this equates to 3000 Ft3/hr of natural gas @ standard conditions (1000 BTU/Ft3 for Natural Gas). Since we are assuming 10:1 air to gas then we know that the combustion air flow will be 30,000 Ft3/hr. RFQ Toolbox September 18, 2018

Stoichiometric Combustion Process RULES OF THUMB Stoichiometric Combustion Process This gives a total of 33,000 Ft3/hr (SCFH). Convert to SCFM = SCFH/60 Stack Flow = 33,000/60 = 550 SCFM RFQ Toolbox September 18, 2018

Questions? 24

Thank you! 25