Question 1
A compressor installed at a whalf (for loading container ships) is capable to give 6 bar.g pressures in the pressure receiver. The compressor is shifted to a site which is 5000 ft above sea level (atmospheric pressure 0.85 bar.a) in the mountains. What is the discharge revised discharge pressure (gauge pressure) of compressor?
Suppose there is no change in the temperature.
Part (a)
Is the assumption of change in the temperature valid for computing the discharge pressure of compressor?
Part (b)
The temperature at the whalf is 35 oC and in the mountains is 19 oC, what is the diminution in volumetric output from compressor?
Question 2
The system on site is a pressure sand filter, with a service curve. The filter is backwashed by using the feed pump, at a higher flow rate, shown as backwash curve.
Service duty point: 3 m3/h
Backwash duty point: 9 m3/h
Part (a)
What is the speed of the pump to get the service and backwash flow rates?
Part (b)
What would be the best manner to control the speed of the pump? Why?
Part (c)
The pump is set up as a fixed speed steady pressure system (pump runs once system pressure reaches 550 kPa, turns off, when pressure drops to 450 kPa plant re-starts) to maintain a system pressure of 500 kPa at discharge of the pump. What would be the service and backwash rates from the pump?
Question 3
We have a reciprocating compressor operating at the 800 rpm. Suction pressure and discharge pressure are held constant through other systems which have nothing to do with the compressor. We raise the speed from 800 to 840 rpm (a 5% raise).
Part a. what is the change in flow rate through the compressor Flow increases by (840/800) or 1.05, or 5% increase?
Part b. what is the change in pressure rise through the compressor.
Part c. what is the change in power that must be delivered to the compressor?