You come across a large boiler with the following characteristics: steam pressure 145 psig measured fuel firing rate: 21 mmbtu/hr (fuel) and steady near high fire stack oxygen: 7% stack temperature: 510°f boiler air inlet temp 80°f deaerator temp/pressure: 225°f/5 psig make-up water temp make-up water flow feedwater conductivity boiler conductivity 70°f 350 gallons/hr (before energy recovery in #11) 185 umhos/cm 3,200 umhos/cm natural gas fuel cost: $5.00/mmbtu find: 1. compute the stack loss efficiency for the boiler 2. are the stack temperature and oxygen reasonable for these operating conditions? explain your answer 3. what oxygen and stack temperature would you recommend if not? what is the efficiency with your chosen values? 4. if the stack temperature increased to 610°f, estimate the stack loss efficiency using the rule of thumb approach. 5. find the steam production rate, based on stack loss efficiency you found in #1. 6. find the boiler size in boiler hp. 7. if the boiler operates at this condition 6,000 hrs/yr. (24 hrs/day 5 days/wk), find the annual fuel cost. 8. compute the blow down rate for the boiler and the blowdown flow in lb/hr 9. find the blowdown loss as a percent of the fuel fired, based on the make-up water temperature. 10. what does the blowdown cost the facility in natural gas cost per year? 11. if we were to flash the blowdown to 5 psig and use in the da, find the steam savings, the annual fuel savings, and annual cost savings. 12. estimate the steam condensate return rate. is it reasonable?