Revamps 2022 Issue

Atm. o gas

E-34

Atm. col. reux drum

Naphtha product

Naphtha PA return from E-11 A-D (Fig. 1)

Naphtha PA to E-11 A-D (Fig. 1)

P-13 A/B P-14 A/B

P-15 A/B

Naphtha coalescer

Jet PA return from E-12 A/B (Fig. 1)

Jet stripper

E-29

Med. diesel PA return from E-20 A/B (Fig. 2 & 6)

Jet product to E-10 A/B (Fig. 1)

Med. diesel stripper

P-16 A/B

Jet PA to E-12 A/B (Fig. 1)

Stripping steam

Med. diesel prod. E-18 A/B (Fig. 1) Med. diesel PA to E-20 A/B (Fig. 2 & 6)

P-17 A/B

P-18 A/B

P-19 A/B

Stripping steam

Heavy diesel stripper

HAGO PA return from E-22 (Fig. 2 & 6)

Heavy diesel product to E-25 (Fig. 2 & 6)

HAGO stripper

P-20 A/B

Stripping steam

HAGO product to E-23 (Fig. 2 & 6)

P-21 A/B

HAGO PA to E-22 (Fig. 2 & 6)

P-22 A/B

Flashed crude from atm. heater (Fig. 2 & 6)

Vapour from preash drum (Fig. 2 & 6)

ATB bypass to E-27 A/B (Fig. 2 & 6)

Stripping steam

P-23 A/B

ATB to Vacuum column (Fig. 4)

Figure 3 Atmospheric column

to perform the required duty. In fouling analysis, the fouling condition is expressed by the following formula:

operating conditions, product distillations and properties, PA temperatures and rates, and the temperature and pres- sure profile for the exchangers in the crude preheat train. These parameters were used to develop a simulation model with the crude feed produced by blending the products from the two columns. The off-gas produced from the cracking of heavy ends in the atmospheric and vacuum heaters was also included as feed to the two columns. The model matched product rates, properties, distillation, and fractionation (gap/over- lap) between adjacent streams and PA rates and supply and return temperatures. In the atmospheric column simulation, the naphtha PA return temperature from E-11 A-D is controlled to achieve the mix temperature of the naphtha PA return and the overhead reflux above the water dew point to prevent free water condensation and minimise corrosion in the atmo- spheric column overhead. The vacuum column simulation is built with a series of

Actual Fouling % = (1 - U Actual /U Clean ) x 100 Design Fouling % = (1 - U Design /U Clean ) x 100

Where: U Actual = Actual overall heat transfer coefficient based on the actual fouling U Clean = Clean overall heat transfer coefficient based on the program rating U Design = Design overall heat transfer coefficient The U Actual is obtained from rigorous modelling of the unit and the crude preheat train exchangers. Rigorous exchanger modelling for test run A unit performance test run for a blended crude slate was generated, which included crude feed and product rates from the atmospheric and vacuum column, column

Revamps 2022