follow some basic economic rules. These rules may be developed with answers
to the following typical questions:
1. If all requirements cannot be met, in which priority order should the various
products be placed?
2. Is it profitable to run the refinery to meet just a fuel oil product requirement,
that is, not to produce waxy distillates at all?
3. What is the optimum octane number severity operation for the reforming
and/or cracking units to meet gasoline requirements?
4. Which are the cheapest middle distillates to import if this becomes necessary
to meet a product slate?
5. Is it economical to utilize a surplus unit capacity to produce feed to another,
for example, to use surplus deasphalting capacity to produce feed for the
catalytic cracker?
6. Does it pay to divert straight run naphtha to refinery fuel in a situation where
naphtha outlet is limiting?
Table 1 is a simplified example of the use of these economic rules to determine
the changing of fuel oil “length” in a middle distillate outlet limiting situation.
The only units considered here are the crude distillation unit (atmospheric and
vacuum), cat reformer unit, and the cat cracker (FCCU). Being a middle
distillate outlet limiting, there will be spare capacity in the units considered,
and all requirements are met except for fuel oil. The economic rule in this case is
that the most profitable plan will be when the crude and fuel oil are at a minimum
while still meeting the requirements of the other products in the slate.
Developing the Running Plan
In most refining companies with more than one refinery installation, running plans
are developed in the company’s corporate offices. In this way, access to the required
Table 1 Changes to running plan to maximize profit
Change base case
Crude
MB/CD
200
Fuel
MB/CD
83
Mid dist
MB/CD
12
Naphtha
MB/CD
40
Cum profit
base case
over $/D
Reduce viscosity of cat feed to
fuel from 46.9 RI to 40.2 RI at
100
F
198.267
81.370
11.65
40.667
595
Reduce residue length from
24 % to 22 %
189.798
73.406
9.685
43.886
3,558
Decrease octane from 50 to
45 res
189.702
73.276
9.179
42.870
4,000
Lower cat plant conversion by
3 %
187.129
71.074
8.667
46.186
5,024
MB thousands of barrels, CD calendar day (or alternatively, SD stream day)
690
D.S.J. Jones and P.R. Pujado ´
to the following typical questions:
1. If all requirements cannot be met, in which priority order should the various
products be placed?
2. Is it profitable to run the refinery to meet just a fuel oil product requirement,
that is, not to produce waxy distillates at all?
3. What is the optimum octane number severity operation for the reforming
and/or cracking units to meet gasoline requirements?
4. Which are the cheapest middle distillates to import if this becomes necessary
to meet a product slate?
5. Is it economical to utilize a surplus unit capacity to produce feed to another,
for example, to use surplus deasphalting capacity to produce feed for the
catalytic cracker?
6. Does it pay to divert straight run naphtha to refinery fuel in a situation where
naphtha outlet is limiting?
Table 1 is a simplified example of the use of these economic rules to determine
the changing of fuel oil “length” in a middle distillate outlet limiting situation.
The only units considered here are the crude distillation unit (atmospheric and
vacuum), cat reformer unit, and the cat cracker (FCCU). Being a middle
distillate outlet limiting, there will be spare capacity in the units considered,
and all requirements are met except for fuel oil. The economic rule in this case is
that the most profitable plan will be when the crude and fuel oil are at a minimum
while still meeting the requirements of the other products in the slate.
Developing the Running Plan
In most refining companies with more than one refinery installation, running plans
are developed in the company’s corporate offices. In this way, access to the required
Table 1 Changes to running plan to maximize profit
Change base case
Crude
MB/CD
200
Fuel
MB/CD
83
Mid dist
MB/CD
12
Naphtha
MB/CD
40
Cum profit
base case
over $/D
Reduce viscosity of cat feed to
fuel from 46.9 RI to 40.2 RI at
100
F
198.267
81.370
11.65
40.667
595
Reduce residue length from
24 % to 22 %
189.798
73.406
9.685
43.886
3,558
Decrease octane from 50 to
45 res
189.702
73.276
9.179
42.870
4,000
Lower cat plant conversion by
3 %
187.129
71.074
8.667
46.186
5,024
MB thousands of barrels, CD calendar day (or alternatively, SD stream day)
690
D.S.J. Jones and P.R. Pujado ´