a combined heat and power system (generates electricity, steam for industrial process and provides heat to satisfying factory space heating load. steam leaves the steam generator at 4.5 x 103 kg/h at 3150 kpa and 316 °c. a fraction of 0.4 of the steam is extracted at 700 kpa for process steam and the rest expands in the intermediate pressure turbine. at the exit of the intermediate turbine a fraction of steam is extracted at 140 kpa for factory space heating and the rest expands through the low pressure turbine to a condenser that is operating at 7 kpa. the working fluid is recovered in an open feedwater heater at a pressure of 140 kpa after which it is sent to the steam generator by a pump that is working an an efficiency of 85%. likewise the pump between the feedwater heater and the condenser operates at an efficiency of 85%. For the system, determine (a) The rate that steam is extracted as process steam in kg/h. (b) The rate that steam is extracted for the heating load in kg/h. (c) The rate of heat transfer for the process steam in kJ/h. (d) The rate of heat transfer for the heating load in kJ/h. (e) The net power developed, in kJ/h. (f) The overall useful energy-based efficiency for the combined heat and power system. A schematic diagram and operating data of the plant are given in the figure below.
a combined heat and power system (generates electricity, steam for industrial process and provides heat to satisfying factory space heating load. steam leaves the steam generator at 4.5 x 103 kg/h at 3150 kpa and 316 °c. a fraction of 0.4 of the steam is extracted at 700 kpa for process steam and the rest expands in the intermediate pressure turbine. at the exit of the intermediate turbine a fraction of steam is extracted at 140 kpa for factory space heating and the rest expands through the low pressure turbine to a condenser that is operating at 7 kpa. the working fluid is recovered in an open feedwater heater at a pressure of 140 kpa after which it is sent to the steam generator by a pump that is working an an efficiency of 85%. likewise the pump between the feedwater heater and the condenser operates at an efficiency of 85%.
For the system, determine
(a) The rate that steam is extracted as process steam in kg/h.
(b) The rate that steam is extracted for the heating load in kg/h.
(c) The rate of heat transfer for the process steam in kJ/h.
(d) The rate of heat transfer for the heating load in kJ/h.
(e) The net power developed, in kJ/h.
(f) The overall useful energy-based efficiency for the combined heat and power system.
A schematic diagram and operating data of the plant are given in the figure below.
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