The design of the crude distillation unit is based on the following cut points.
Table 7: Design TBP cut points.
Products TBP cut point (ºC)
Full Range Naphtha / Kerosene 165
Kerosene / Light Gas Oil 205
Light Gas Oil / Heavy Gas Oil 330 Heavy Gas Oil / Atmospheric residue 370
The resulting flows of these TBP cut points correspond with the normal unit operating case (see chapters 1.4.1 and 1.4.2). Other operating cases are shown in “1.4.3 Flexibility cases”.
1.4.1. Bach Ho crude
According to the TBP cut points defined in Table 7: Design TBP cut points, the resulting flows for Bach Ho crude oil are:
Table 8: Bach Ho case's product distribution.
Product Flow (kg/h) % Wt of feed (water included)
LPG 2181 0.27
Naphtha 108314 13.30
Kerosene 51188 6.28
Light Gas Oil 170716 20.96
Heavy Gas Oil 69822 8.57
Residue 407324 50.01
1.4.2. Dubai crude
The design TBP cut points lead to the following flows for Dubai crude oil:
Table 9: Dubai case's product distribution.
Product Flow (Kg/h) % Wt of feed (water included)
LPG 7000 0.86
Naphtha 130072 16.01
Kerosene 48747 6.00
Light Gas Oil 154839 19.06
Heavy Gas Oil 64933 7.99
Residue 403303 49.64
1.4.3. Flexibility cases
As stated in 1.1, the plant is designed to operate with 100 % Bach Ho case or 100 % Dubai case. Furthermore, the unit is design to operate with different TBP cut point (see the following sections on this point). In order to change from one case to another, the flow set
points should be changed to the values shown in this section, in order to achieve the required product quality.
All elements of the CDU have sufficient sizing margins incorporated into the design to achieve the flexibility requirements described below. For affected equipment, this flexibility is considered as an alternative (i.e. not additional) to the design margins.
The pumparound flows’ and duties’ vary from Bach Ho to Dubai operation case, but inside the same feed from one flexibility case to another the same value should be used. The flows and duties are represented in the following table
Table 10: Pumparound flows' and duties' for Bach Ho and Dubai cases Bach Ho Case Dubai Case
Flow / (kg/h)
Duty / (kW)
Flow / (kg/h)
Duty / (kW) Kerosene
pumparound 211124 9000 211110 9000 LGO pumparound 758719 29065 758676 31000 HGO pumparound 134995 4925 134963 4925
Top P/A duty is controlled by T-1101 overhead temperature (011-TIC-076), in order to adjust the overhead flowrate to the values required to each flexibility case.
As a guideline the next table shows estimated overhead temperatures for each flexibility cases. These values must be adjusted in field.
Table 11: Expected overhead temperatures for flexibility cases.
Bach Ho Dubai
Design 123.6 123.7
Maximum Naphtha 129.6 127.5 Minimum Naphtha 126.2 123.3 Maximum Kerosene 126.1 123.6 Minimum Kerosene 129.3 127.2
Maximum LGO 125.4 123.7
Minimum LGO 125.7 124.2
Maximum HGO 125.7 123.9
It must be noted that if the plant is operating with a mix of Bach Ho and Dubai case, the process water from P-1121 can not be used to feed D-1109 as it will contain H2S traces.
The stream numbers shown in the following chapters refer to PFD’s stream numbers.
1.4.3.1. Naphtha flexibility cut point
In order to maximize or minimize kerosene production, naphtha TBP cut point can be modified in the range of 160 ºC to 170 ºC. These TBP cut points correspond with minimum and maximum naphtha production cases, respectively.
1.4.3.1.1. Maximum naphtha production
This flexibility case’s flows, for both crude oils, are summarized in the table below.
Table 12: Maximum naphtha production flexibility cases.
1.4.3.1.2. Minimum naphtha production
When the plant is operating with the minimum naphtha flexibility case for both crude oils, a Naphtha recirculation from P-1110 to T-1101 head via line PL-110080 is required, in order to avoid water condensation in T-1101 top trays. The amount of naphtha recirculated varies from one case to another.
Table 13: Recirculated flow for minimum naphtha cases.
Case Flow / (kg/h) Bach Ho 28000
Dubai 23000
The resulting flows for this operating case are shown in the following table:
Table 14: Minimum naphtha production flexibility case.
1.4.3.2. Kerosene flexibility cut point
Kerosene normal cut point range of 165 ºC to 205 ºC can be varied to achieve product requirements. In order to maximise scope for producing kerosene of acceptable quality; the CDU is designed to produce a minimum TBP cut range of 170 ºC to 200 ºC. Additionally, in order to maximise kerosene production, and if permitted by product quality considerations, the CDU is designed to produce a maximum TBP cut range of 160 ºC to 210 ºC.
1.4.3.2.1. Maximum kerosene production
Kerosene flows for this flexibility case (TBP cut range of 160 ºC to 210 ºC) are summarized in the table below:
Table 15: Maximum kerosene production flexibility case.
1.4.3.2.2. Minimum kerosene production
The resulting flows for this flexibility case are shown in the following table.
Table 16: Minimum kerosene production flexibility case.
1.4.3.3. Diesel flexibility cut point
In order to potentially improve diesel blending flexibility, the CDU is designed to achieve a TBP cut point of 340 ºC between the light gas oil and the heavy gas oil products. Also, in order to provide additional flexibility for the campaign production of military diesel, the CDU is designed to achieve a TBP cut point of 320 ºC between the light gas oil and heavy gas oil products.
Based on the above, three operating cases have been considered: Maximum light gas oil production (TBP cut range of 200 ºC to 340 ºC), minimum light gas oil production (TBP cut range of 210 ºC to 320 ºC) and maximum heavy gas oil production (TBP cut range of 320 ºC to 370 ºC).
These flexibility cases’ flowrates are shown in chapters 1.4.3.3.1, 1.4.3.3.2 and 1.4.3.3.3.
1.4.3.3.1. Maximum light gas oil production
Maximum light gas oil production is summarized in the table below.
Table 17: Maximum light gas oil production.
1.4.3.3.2. Minimum light gas oil production
This flexibility case’s flows for both crude oils are shown in the table below.
Table 18: Minimum light gas oil production.
1.4.3.3.3. Maximum heavy gas oil production This case can be seen in the following table.
Table 19: Maximum heavy gas oil production.