Crude preheat train

United States discoveries of, 78 597 Crude petroleum, 24 255 Crude preheat trains, 73 221-223 design methodology for, 73 223-224 Crudes... 

Fouling is a very serious issue for crude preheat train in oil refining plants and it is characterized by the following root causes ... 

Low Velocity Low velocity can promote accumulation of fouling deposits. The desirable velocity for heat exchangers for the crude preheat train is between 6 and 7 ft/s. 

For the crude preheat train in the refinery plant, three beneficial modifications are identified. Modifications 1 and 2 add a new shell to each of the feed preheat exchangers serviced by the diesel pump-around (PA). Modification 3 adds surface area to the diesel product run down heat exchanger. Before implementing these changes, it is crucial to make sure that the existing pump can handle the increased diesel PA flow and the increase can be tolerated in product cut points. These modifications can save 47 million Btu/h of fuel in the crude heaters, equating to cost savings of 2.3 million per year. With only a 2.2 million installed cost, this project provides a fast payback. 

Crude preheat train, with crude on tube side or sometimes on shell side (see next section)... 

A typical flow diagram is shown in Fig. 18.13 The desalter operation is incorporated into the preheat train of the crude distillation unit to conserve energy. Depending on the characteristics of the hydrocarbon feedstock,... 

Lamboume, G.A. and Durrieu, M., 1986, Fouling in crude oil preheat trains, in Taborek, J., Hewitt, G.H. and Afgan, M. eds. Heat Exchangers Theory and Practice. Hemisphere Pub. Corp., Washington. 

FIGURE 10.19. Preheat train outlet temperature versus crude bubble points. 

Heat transfer in crude exchangers often declines because of tube-side fouling. The difference in crude preheat may be 50 "F for a dirty vs a clean exchanger train. 

Preheat Train, Crude Heaters, Crude Tower, Atmospheric Flash Tower, Syn Tower, HCC Heaters, Reactor, Kiln, Steam Coils, Air Blower, Cyclone, Main Fractionator, Unsaturated Gas Plant... 

Another example from oil refineries is in crude preheat service with vacuum resid again on the shell side (with the helical baffles). Once again, similar results are seen as described above, with less fouling, reduced rate of increase in pressure drop, and better maintenance of heat-transfer coefficient as compared to the conventional shell-and-tube exchanger design. Our more direct experience of this comes from current practice in the United States, but we have also seen evidence of similar applications in Australia, as discussed in a recent article on the subject of crude preheat exchanger train redesign. ... 

The crude distillation unit consumes 20%-30% [13] of the total energy required to distill a given crude into products. Therefore, it is critical to optimize and recover as much heat as possible from heat streams throughout the refinery to optimally heat and vaporize the crude for fractionation. The preheat train consists of heat-exchangers that incrementally heat up the crude feed using hot streams from the crude distillation and other downstream imits in the refinery. Crude exits in the preheat train at around 250 °C [13]. 

In operation, the crude oil preheat exchangers will gradually become fouled and lose effectiveness over a period of months. The piping of the exchange train needs to be arranged to permit cleaning on stream. 

Increased vaporization of the lighter crude through the preheat exchanger train and furnace increases pressure drop, which reduces the capacity of the crude charge pump. 

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