Page 98 - Sustainability in the Process Industry Integration and Optimization

P r o c e s s I n t e g r a t i o n f o r I m p r ov i n g E n e r g y E f f i c i e n c y 75

ΔT MIN = 20°C
ΔH[MW] T*[°C]
21.90 440 500
450
29.40 410
400
23.82 131 350
18.00 118 300
T*[°C] 250
1.80 115
200
0.00 94 150
4.30 91 100
50
11.50 79
0
15.00 30 0 10 20 30 40
ΔH [MW]

FIGURE 4.34 Heat-pump sizing example: Initial data of the GCC.

FIGURE 4.35 140
Heat-pump sizing
example: Attempt 1.
120
Q SINK
100
Maximum
T* [°C] 80
Q SOURCE
60

40
20
0 5 10 15 20 25
ΔH [MW]

and source heat loads, the smaller one is chosen as a basis. Here the
sink bound is smaller, so the sink is sized to its upper
bound: Q = Q = 2.634 MW. From this, the required pump
sink sink,max
power consumption is computed to be 0.588 MW. As a result, the
actual source load for the heat pump is 2.046 MW. Comparing this
value with the upper bound of 6.9 MW, it is evident that the source
heat availability is considerably underutilized.
A different selection of source and sink temperatures is needed if
the source availability is to be better utilized. As a second attempt,
the sink temperature is increased from 100°C to 110°C. The maximum
source heat remains 6.9 MW, but the maximum sink capacity
increases from 2.634 to 7.024 MW. This results in the desired