Chemical Process Design and Integration. Robin Smith. Chapter 23 Exercise 10

10. A company is considering implementing a cogeneration scheme. At the moment, the company is supplied with 50,000 MWh of electricity from the grid each year and the company produces steam of 80,000 MWh per year from a gas-fired boiler. It is proposed to replace this arrangement with a gas turbine. With the cogeneration scheme, the waste heat from the gas turbine can be used for the steam generation to satisfy the steam demand. Assume the power generation efficiency of gas turbine = 0.35, average electricity tariff = 0.063 $-kw-!, gas price = 0.015 $.kWh-1, boiler efficiency = 0.9, the installed cost of the gas turbine is 1000 $-kw- and the company operates for 8000 hours annually. a. Calculate the operating costs for both the current operating system and the proposed cogeneration scheme. b. Determine the savings and payback time that can be achieved by implementing the cogeneration scheme. c. What issues should be considered in recovering the exhaust heat from a gas turbine