Q2. Pinch technology tutorial 1
A Network of heat exchangers is described below in data table 1.
A) Produce a table showing the energy available from or required by each stream.
[5 marks]
B) Construct the incremental temperature–enthalpy table for the hot and cold streams.
[10 marks]
C) For a minimum temperature difference of 10 ˚C and the data given below construct the composite temperature enthalpy curves.
[10 marks]
D) Construct the shifted temperature curves.
[5 marks]
E) Construct the grand composite enthalpy curve and identify the pinch temperature.
[5 marks]
F) Determine the minimum utility heat input and the minimum heat lost to a heat sink.
[5 marks]
G) Use the problem table method to check your answer
[15 marks]
H) Determine the optimum sequence for the exchangers
[15 marks]
Data Table 1
Stream Number
1
2
3
4
5
6
7
Stream Enthalpy
7
2
3
8
9
2
Temperature in ºC
300
150
200
190
90
40
Temperature out ºC
150
50
50
290
190
190
PROBLEM 3.
Water at 15 ˚C is fed to the top of a spray column by a centrifugal pump from a bulk storage tank at a rate of 50 kg/min. The storage tank is 15 m in diameter 3 m deep and the level within the tank is maintained at 2 m by a float valve connected to the mains water supply.
The pump draws water from the bottom of the bulk storage tank at ground level and discharges it though a nozzle mounted in the roof of a spray tower 25m high. The pipes connecting the tank, pump and nozzle are all 5cm bore. The nozzle has an outlet diameter of 1 cm and is 3 cm long. The spray tower is vented to atmosphere and is drained at its base.
a) Draw a diagram of this process
b) The outlet velocities of the nozzles
c) The pressure at the inlet of the nozzle
d) The Power input by the pump assuming 100% efficiency
e) The pump actually operates at 80 % efficiency, recalculate the power input to the pump.