Crude oil processing scheme for reducing operating costs in the CDU
Development of crude oil distillation processing schemes to significantly reduce external energy and stripping steam demand
Sunil Kumar and Avinash Mhetre CSIR-Indian Institute of Petroleum
T he crude distillation unit (CDU) is the highest throughput processing unit in the refinery to frac - tionate whole crude slate into desired boiling range fractions. Conventional processing of crude petroleum oil through the CDU consumes huge amounts of thermal energy and stripping steam, so refiners are always looking to improve the CDU’s operation and energy efficiency to improve their gross margin and reduce carbon emissions. There are many approaches to CDU energy and operat - ing cost reduction. Some widely used approaches include optimising the operating conditions of crude distillation columns, improving the integration of distillation and heat exchanger network (HEN), improving the design and ret - rofitting of HEN, and synthesizing the improved crude processing schemes (CDU design configuration) further to reduce the operating cost of the optimised process. The CSIR-Indian Institute of Petroleum (CSIR-IIP) has developed a new crude oil distillation processing scheme that takes innovative steps to tackle these issues. These
include adding process water to desalted crude, super - heating flash drum (FD) vapour, and utilising the strip - ping effect of superheated hydrocarbon vapour to reduce external energy and striping steam demand significantly. Patents on the developed scheme have been granted in India and the US. Common refinery crude oil processing schemes The three most common crude oil processing schemes in refineries are conventional, prefractionation column inte - grated (PFCI), and flash drum integrated (FDI) schemes, the schematic of which is shown in Figure 1 . 1 Crude oil is preheated in HENs using hot process streams. The pre - heated crude oil is processed in the desalter to remove the salt using water. The desalted crude oil is further heated using HEN. The heated crude is routed to the atmospheric distillation col - umn (ADC)-fired furnace in the conventional scheme, to the prefractionation column (PFC) to remove light naphtha in
Condenser
Unstabilised light naphtha
Water
Naphtha
PA1
Steam
Heavy naphtha
Crude oil routing in FC integrated method
ADC
PA2
To above ash zone
Crude oil
Water
Steam
PA3
Kerosene
HEN 1
To ash zone
Flash zone
Desalter
Steam
Crude oil routing in
Diesel
FD
FC integrated method
VD top vapour
Sour water
HEN 2
Bottom stripping steam
Crude oil routing in conventional method
Long residue
ADC- furnace
LVGO
HEN
VDC
HVGO
HEN
VDC- furnace
Coil steam
Slop
Flash zone
HEN 3
Vacuum residue
Stripping steam
Figure 1 Schematic of most common crude processing schemes in refineries 1
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PTQ Q1 2023
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