Environmental Engineering Reference
In-Depth Information
Table 2.
TS
TT
DH
CP
Stream Name
[C]
[C]
[MM kCal/hr]
[MM kCal/C]
37.46
84.16
16.02
0.343041
PreDesalter
84.16
90.42
2.27
0.36262
90.42
126.7
13.74
0.378721
125
158.9
13.4833
0.397738
PreFlash
158.9
193
14.216
0.41689
188
225.1
14.8257
0.399614
AfterFlash
225.1
265
16.64
0.417043
265
378
64.52
0.570974
TPA
160.5
75
16.02
0.187369
185.1
105
2.27
2.83E-02
Kero
105
61
1.12
2.55E-02
61
40
0.5
2.38E-02
241.2
103.3
13.74
9.96E-02
LDO Prod
103.3
60
3.68
8.50E-02
IPA
253.9
138
13.43
0.115876
318.2
198.4
4.06
3.39E-02
HDO Prod
198.4
60
3.89
2.81E-02
BPA
327.5
225
10.35
0.100976
346.4
259.7
16.65
0.192042
RCO
259.7
169.9
15.52
0.172829
169.9
80
13.23
0.147164
The first step in applying pinch technology is to find for a reasonable minimum approach
temperature the minimum heating utility and minimum cooling utilities required for this crude
unit. These targets are shown in Figure 10.
The heating utility which is our main focus in this application is about 48 MM Kcal/h
Using pinch design method (PDM) to synthesis the crude pre-heat train, to reach desired
level of waste heat recovery and to minimize the heating load of the crude heater results in the
network below in Figure 11. The network exhibits three splits in the cold crude stream. First
split happens before the crude desalter, the second after the desalter and before the flash drum
and the third after the flash drum up to the crude heater.
As you notice both heating and cooling utilities are considered being of the same
important. In most cases in oil refining heating utility is more expensive than cooling water.
Therefore, many designer put more emphasis on saving in heating utility since it also reduce
emissions than saving on the cold side. Another very important objective in designing new
pre-heat train in crude distillation unit is the number of units of the heat exchangers, less
sophisticated configuration and the easiness of heat exchanger network operation and
maintenance. This need pushes the plant designers to the extreme in considering the easiness
of operation to the extent that they design networks that do not give enough attention to
decent level of waste heat recovery and GHG emissions reduction compared with their
emphasis on capital investment, maintenance and operation of the network.