I have to audit thermal efficiency of cement kiln system. I've made mass and heat balance for that system. Heat inputs consist of raw mix heat, air heat, coal heat, and coal combustion heat. Heat outputs consist of clinker heat, exit gas heat, dust heat, calcination heat, clinkerization heat, convection heat, and radiation heat.
I'm still confused about how to calculate thermal efficiency of the system. I've searched in many journals, but the equation is different in each journal.
It looks to me that you did all the right things in calculating the input energy streams and the output energy streams. You also calculated the heat losses from the kiln by radiation and convection. All what you need to do now is to sum up all the inputs and all the outputs to calculate the thermal efficiency:
Thermal efficiency = (sum of energy outputs) / (sum of all energy inputs.
Hope this helps answer your question.
Professor Yehia Khalil
Yale University
USA
Dear Prof Yehia F. Khalil,
But, sum of energy outputs equal to sum of energy inputs. So, I can't calculate the thermal efficiency by that equation. Because, I calculate heat loss by convection and radiation from the heat balance.
I've read many journals about thermal efficiency calculation. There is journal said that thermal efficiency = (calcination heat + clinkerization heat)/coal combustion heat. But in other journal said that thermal efficiency = (total heat input - heat loss by convection and radiation)/total heat input.
Which equation is right and consistent with the definition of thermal efficiency in thermodynamics? Thermodynamics said that thermal efficiency = what we get/what we pay for.
Thermal efficiency = Total Output energy /Total input energy
Total energy include heat, work (power), enthalpy, kinetic energy(velocity) and potential energy(elevation).
Dear Prof. Duraid and Prof. Yehia,
Thank you for your answer. I've completed this project based on your suggestions.
- Badges
- Science topic
- Similar topics
- Engineering
- Chemical Engineering