Linking Process Simulators to a Refinery Linear Programming Model

25 Linking Process Simulators to a Refinery Linear Programming Model ANDRE W. POLLACK and W. DONALD LIEDER 1

Downloaded by AUBURN UNIV on December 26, 2017 | http://pubs.acs.org Publication Date: May 30, 1980 | doi: 10.1021/bk-1980-0124.ch025

Suntech, Inc., P.O. Box 1135, Marcus Hook, PA 19061

The use of linear programming to optimize the flow of process streams through a petroleum refinery began in the mid-1950's (Symonds, 1955: Manne, 1956). Now, almost twenty-five years later, it is safe to say that one half of U.S. refining capacity is represented by linear programming or LP models which are routinely optimized to schedule operations, evaluate feedstocks, and study new process configurations. The database for these refinery LP models is a mixture of economic and technical inputs. Economic inputs include the availability and price of refinery raw materials, the variable cost of operating the individual process units, and the demand and price for refinery products. Technical inputs include refinery product specifications as well as the operating constraints, usage of equipment and utilities, product yields, and product properties for each process unit. The economic inputs are of vital concern to a petroleum refining company and various groups within the company are charged with monitoring and forecasting this information. For this reason, economic inputs are probably the easiest values to maintain and update in the refinery LP database. And for the same reason, specifications on refinery products are also easy to maintain and update. Plant operating constraints are readily obtained from design data and operating history. There is usually little need to update these constraints unless the plant is debottlenecked or we want to study some new process configuration. Unfortunately, the remaining technical inputs which characterize plant performance are extremely difficult to maintain and update. For whether we measure the usage of equipment and u t i l i t i e s , the product yields, and the product properties directly from a plant survey or whether we compute these inputs using a process simulator fitted to the plant, one fact is uncomfortably clear. The values are good only for the feed and operating concurrent Address: Sun Petroleum Products Company, Toledo, OH. -1

0-8412-0549-3/80/47-124-437$05.00/0 © 1980 American Chemical Society

Squires and Reklaitis; Computer Applications to Chemical Engineering ACS Symposium Series; American Chemical Society: Washington, DC, 1980.

COMPUTER

438

ditions run.

at

the

That

for

is

the

survey or

TO

CHEMICAL

specified

in

new

sor.

facilitate

automatically generates and stores

and the product properties

processor

are

catalytic

cracker

In

for

s i x process

three already e x i s t i n g process or FCC simulator,

paper,

the

units at Sun

Linked

to

the pre

simulators: a

fluid

a hydrocracker simulator, and

we describe the preprocessor,

and how we linked

results

in

the product

reformer simulator.

this

ulators,

a

the maintenance and updating of plant p e r f o r

This preprocessor

a catalytic

at

we have developed and implemented an LP preproces

database the usage of equipment and u t i l i t i e s ,

yields,

these

level.

Petroleum Products Company's Toledo Refinery.


inputs

approximate plant performance on a new feed or

operating To

The

the computer,

why the r e f i n e r y LP database often contains

to

mance inputs,

LP

ENGINEERING

more than one plant operation and the LP model "blends"

operations

LP

time of

APPLICATIONS

made possible

them together.

the process

We also

through the use of

the

sim

discuss some

preprocessor.

Preprocessor The

operation of

Figure 1.

In

There are

the

the preprocessor f i v e basic

is

ο

Select

ο

Build and report

ο

Generate crude data

crude assay

data

input

tables

ο

Generate process

ο

Build and access LP data

first

step,

shown schematically in

steps:

data

the preprocessor

tables accesses

the disc

file

which contains a l l of Sun Petroleum Products Company's crude assays.

The preprocessor

which the user has crude mix or

to be made available to

mental r e f i n e r y feed. any

five In

tables

extracts assay data

The user

those

part

of

the LP model as

can i d e n t i f y

up to

crudes the base

an i n c r e

ten crudes

of which can be designated as incremental. the

second step,

the preprocessor builds

showing the extracted

also prints out

in

tabular

has s p e c i f i e d by card input

crude assay data.

form a l l for

Crude

ο

Propane deasphalter

distillation

stored

may

alter

user

units:

FCC

ο

Gas o i l hydrocracker

ο

Motor reformer

ο

BTX reformer

in

information which the

unit

Base operating conditions and unit are

and p r i n t s out The preprocessor

the following process

ο ο

or

for

i d e n t i f i e d by card input as

the preprocessor.

any of

the base values

parameters

The user, to

for

these s i x units

through card

input,

define a new base operation

to add one or more alternate operations. In

the

third

properties of

step,

the preprocessor

generates

the products obtained by crude

the y i e l d s and

distillation


and

POLLACK

A N D

LiEDER

Refinery

Linear

Programming

439

CRUDE


SELECT USER

CRUDE

INPUT

ASSAY

ASSAY

DATABASE

DATA

BUILD/REPORT INPUT

INPUT

TABLES

DATA TABLES

GENERATE CRUDE DATA

PROCESS SIMULATOR

GENERATE

SUBROUTINES

PROCESS DATA

BUILD/ACCESS LP

L P DATA

DATA

TABLES

uO

TOLEDO LP DATABASE

TABLES

Figure 1.

Program flowsheet of LP preprocessor


COMPUTER

440 propane deasphalting of refinery and

feed.

into results

asphalting operations In

the

and

for

calls

in


user.

the

For each of

for a l l base and alternate operations the

FCC operations,

the

plus vacuum gas

a l l of

the hydrocracker operations,

For a l l of are

light

cycle

eration.

those of

are

those of

s p e c i f i e d by the

feed properties

are

o i l from the base crude deasphalter the

overhead.

feed properties

are

Finally,

computes

the the

operations,

the

from the base hydrocracker op

the BTX reformer

hydrocrackate

for

operations,

the

fifth

step,

inputs into stored

in

with a

fixed

the base operation.

the preprocessor

tables

oper

the process simulator

feed property about

and f i n a l

same time they are

feed prop

from the base hydrocracker

each process u n i t ,

change in plant performance associated

plant performance

feed prop

the BTX naphtha from the base crude mix

perturbation of each

which are

assembles

printed out

the

at

the

the Toledo LP database.

FCC Simulator The

original

FCC simulator was a stand-alone

gram purchased from the Pace Company of Houston, gram proceeds

through a set

the performance of ator

sections

three nested

the

cycle

Conversion per pass

ο

Regenerator

o i l which

is

usually

option, cycle

fractionator

Toledo

is

back to

the

fraction-

There are Figure

2):

recycled,

The program offers user

specifies

than gasoline can

the reactor:

a prime hydrocracker

of which must be recycled

unit.

The pro predict

heat balance

three FCC products heavier

at

the

to

and product

cracking u n i t .

loops in the program (see

o i l which part

equations

regenerator

catalytic

ο

be recycled from the

oil,

correlating

computer pro Texas.

Recycle rate and composition

Part or a l l of cycle

of

reactor,

of a f l u i d convergence

ο

to

the

and product

the motor naphtha from the base crude mix

For a l l of

blended with l i g h t

The

the prepro

o i l from the base FCC oper

the motor reformer

blended with heavy hydrocrackate

In

per

reformer

the heavy naphtha from the base crude mix blended with

a s p e c i f i e d f r a c t i o n of

ation.

motor

product y i e l d s ,

blended with a s p e c i f i e d f r a c t i o n of

erties

generates plant

these process u n i t s ,

For

erties

crude

and de-

the r e f i n e r y .

mix

ation.

laboratory

distillation

the preprocessor

the atmospheric

those of

each incremental

the appropriate process simulator which computes

For a l l of

those of

ENGINEERING

simple correlations

transform the

usage of equipment and u t i l i t i e s , properties

CHEMICAL

the FCC, gas o i l hydrocracker,

BTX reformer.

cessor

to

uses only

applicable to

fourth step,

formance data

TO

the base crude mix and of

The preprocessor

interpolation procedures

assay data

APPLICATIONS

five

six

feed,

and the bottoms to

out of

the

options.

light

the heavy

or s l u r r y

return entrained

recycle

the

catalyst For any

following eight

variables:


re

25.

POLLACK

A N D

LiEDER

Refinery

Linear

Programming

441

SET UP RUN USER INPUT


COMPUTE FJ?ESH FEED CRACKABILITY

FCC PROGRAM CONSTANTS

COMPUTE TOTAL CYCLE OIL PROPERTIES

COMPUTE RECYCLE 8 WITHDRAWAL RATES

ADJUST CYCLE OIL CUTPOINTS - IF NECESSARY RESET REGENERATOR VARIABLE

COMPUTE CAT CIRCULATION RATE COMPUTE NEW CONVERSION PER PASS YES

COMPUTE REGENERATOR HEAT BALANCE

COMPUTE FCC PERFORMANCE

Figure 2. Program of FCC simulator


COMPUTER

442

The

the

CHEMICAL

Withdrawal rate of l i g h t cycle o i l

ο

Recycle rate of

l i g h t cycle o i l

ο

I n i t i a l boiling

point of heavy cycle o i l

ο

Withdrawal rate of heavy cycle o i l

ο

Recycle rate of heavy cycle

ο

Final boiling

ο

Withdrawal rate of

ο

Recycle

slurry o i l

slurry o i l are

is

determined by

the p r i n c i p a l

predicting recycle this

oil

variable

is

correlating

and supports

In lected

the

the

In

resolved by computing the

conversion per

and outer

regenerator variable

catalyst

loop, to

catalyst

the reactor heat

pass.

the program adjusts

satisfy

in

the

a user-se

the heat balance

in

the

regenerator.

The a

third

variable

rate and composition.

c i r c u l a t i o n rate which simultaneously s a t i s f i e s balance

trial-and-error

loop.

Conversion per pass second loop,

ENGINEERING

point of heavy cycle o i l

rate of

inner convergence

the equations


TO

o

remaining three variables

in

APPLICATIONS

FCC simulator program was converted

few years ago and incorporated

model representing finery.

It

is

a complex of process units

this

to

subroutine form

into a nonlinear programming in

the Toledo

re

subroutine version which has been linked with

the LP preprocessor. The

Hydrocracker Simulator The

o r i g i n a l hydrocracker

as a stand-alone

fundamental reaction of

The program is based on a

k i n e t i c model and predicts

the

performance

two multi-bed reactors with inter-bed quench zones,

low a

simulator was developed in-house

computer program.

pressure

separators,

simplified

cracker

flowsheet

feed

is

and a product

of

the Toledo hydrocracker.

defined by twenty-six

go hydrocracking, ring

fractionator.

opening,

high and Figure 3

components which can under

hydrodealkylation, hydrogénation

and

denitrogenation reactions.

Reaction rate expressions

the

dual

catalyst

fects

function nature of

the

is

The hydro-

and the

reflect

inhibiting

ef-

of adsorption. The

program numerically integrates

nent and heat balances

for

the d i f f e r e n t i a l compo-

the combined feed and recycle

through the

i n d i v i d u a l beds of both reactors

addition of

cold quench gas between reactor beds and the

cycling

of

There are

fractionator two nested

bottoms

to

convergence

the

accounting

second reactor

gas for

the

re-

inlet.

loops in the program (see

Figure

4):

In bottoms times

the

ο

Recycle rate and composition

ο

Conversion per pass

inner loop,

recycle

are

the

rate and composition of

determined by successive

accelerated by a secant method.

of recycle

plus makeup gas

routed

to

fractionator

substitution some

The rate and composition the

reactor

i n l e t s and



VIRGIN HEAVY NAPHTHA

Figure 3.

Process flowsheet of Toledo hydrocracker

FRACTIONATOR BOTTOMS RECYCLE

HEAVY HYDROCRACKATE

FRACTIONATION SECTION

LIGHT HYDROCRACKATE

• GAS + GASOLINE

MAKEUP HYDROGEN


COMPUTER

444

APPLICATIONS

T O CHEMICAL

ENGINEERING

SET UP

USER INPUT

RUN


INTEGRATE HYDROCRACKER RATE EQUATIONS

RESET

COMPUTE

RESET

INLET/QUENCH

SEPARATOR

RECYCLE

TEMPERATURES

VAPOR/LIQUID

RATES AND

STREAMS

COMPOSITIONS

IN 2

n d

REACTOR

COMPUTE FRACTIONATION STREAMS

YES

COMPUTE HYDROCRACKER PERFORMANCE

Figure 4.

Program flowsheet of hydrocracker simulator



25.

POLLACK

A N D

LiEDER

Refinery

Linear

Programming

445

quench zones are a l s o determined in the same inner loop using successive s u b s t i t u t i o n . In the outer loop, bed i n l e t temperatures in the second r e actor are a l l adjusted by equal increments as the program con verges on a t a r g e t conversion per pass. The hydrocracker simulator was a l s o converted to subroutine form f o r i n c l u s i o n in the n o n l i n e a r programming model of the Toledo process complex. The subroutine was considerably s i m p l i f i e d , however, to save computer time and memory. The major d i f ferences are: (1) the f r a c t i o n a t i o n s e c t i o n is represented by c o r r e l a t i o n s i n s t e a d of by a multi-stage s e p a r a t i o n model, (2) high pressure f l a s h c a l c u l a t i o n s use f i x e d e q u i l i b r i u m K-values instead of r e - e v a l u a t i n g them as a f u n c t i o n of composition, and (3) the beds in each r e a c t o r are t r e a t e d as one isothermal bed, e l i m i n a t i n g the need f o r heat balance equations. The Reformer Simulator The o r i g i n a l reformer simulator was a stand-alone computer program purchased from the Pace Company o f Houston, Texas. The program is based on a r e a c t i o n k i n e t i c model and p r e d i c t s the performance o f up to f i v e f i x e d bed r e a c t o r s with i n t e r h e a t e r s and a high pressure f l a s h separator. In i t s present v e r s i o n , the stand-alone program handles a feed defined by t h i r t y - n i n e components undergoing dehydrogenation, d e h y d r o c y c l i z a t i o n , hydrocracking, h y d r o d e a l k y l a t i o n , and i s o m e r i z a t i o n r e a c t i o n s . Re a c t i o n r a t e expressions r e f l e c t the dual f u n c t i o n nature of the c a t a l y s t , but a d s o r p t i o n e f f e c t s are neglected. The program nu m e r i c a l l y i n t e g r a t e s the d i f f e r e n t i a l component and heat balances f o r the combined feed and r e c y c l e gas through the r e a c t o r s , per forms the f l a s h c a l c u l a t i o n s in the high pressure separator, and computes the p r o p e r t i e s of the C 5 + p o r t i o n of the reformer prod uct. There are two nested loops in the program (see Figure 5 ) : ο Composition of the r e c y c l e gas ο Octane number of the C 5 + reformate In the inner loop, the composition of the hydrogen r e c y c l e gas is determined by successive s u b s t i t u t i o n . I f a target r e f ormate octane is s p e c i f i e d , an outer loop adjusts the i n l e t temp eratures to a l l the r e a c t o r s by equal increments u n t i l the t a r g e t is reached. The reformer simulator was converted to subroutine form f o r i n c l u s i o n in n o n l i n e a r programming models of two r e f i n e r y com plexes. To save computer time and memory, the subroutine uses a l i n e a r i z e d v e r s i o n of the o r i g i n a l k i n e t i c model, with 28 compo nents and 33 r e a c t i o n s . Instead of numerical i n t e g r a t i o n , the l i n e a r i z e d model is solved a n a l y t i c a l l y at constant temperature, pressure, and t o t a l mois using s p e c i a l subroutines to f i n d the eigenvalues and eigenvectors of the r e a c t i o n r a t e constant matrix.



446

COMPUTER

APPLICATIONS

USER

S E T UP

INPUT

RUN

T O CHEMICAL

ENGINEERING

D

REFORMER PROGRAM

CONSTANTS

INTEGRATE REFORMER RATE EQUATIONS

RESET

COMPUTE

RESET

REFORMER

SEPARATOR

RECYCLE

INLET

VAPOR/LIQUID

COMPOSITION

TEMPERATURES

STREAMS

Ï YES

COMPUTE

C + 5

REFORMATE PROPERTIES

COMPUTE REFORMER PERFORMANCE

Figure 5.

Program flowsheet of reformer simulator


25.

POLLACK

Linking

FCC simulator

requires

of measured properties

such as

bottom carbon,

as

as

well

surements such as and

in

the

preprocessor adjusting cording gas

in

to

oils

assay

creates

the

the

standard

the

for

of

oils

of

gas

s p e c i f i e d for

in

the

the base mix

atmospheric

unit and (2) according

the properties

done by l i n e a r

tween i n i t i a l

and f i n a l

Properties

are

to

of

points

as

blended according

the

to

surements expressed in weight percent are gravity

to

put

them on a weight

of blending molecular weight, gravity

FCC simulator

operation

operating values

and vacuum the

atmospheric

its

proportion

deasphalter

standard

crude

the midpoint be

independent

volume so

vari

that mea

m u l t i p l i e d by s p e c i f i c

per unit volume b a s i s .

the

(1)

preprocessor

blends

Instead specific

divided by molecular weight.

The its

the

re

ac

computing

of

i n t e r p o l a t i o n using

boiling

are The

the base FCC feed by

each crude

from each crude

is

all

of

requires

a description of

equipment dimensions and

and unit parameters.

these are

however,

specifying

also

terms of

variables

for

user,

in

stored

can change the

in

Standard or

the

values

preprocessor of

Seven operating variables bed

ο

any of

e f f i c i e n c y and gasoline

Steam and operating

ο

Maximum regenerator bed temperature

cost

following

FCC simulator was linked

to

the preprocessor

simulator would sometimes

that

the

in either

the

recycle

case

happens, boiling

loop or

the

user

point of

per pass

for

the base or

the

user

in

the

following whenever

selecting

can change the the

fail

to

heavy cycle

initial

of

Values of

the

FCC simulator operation or

when f a i l u r e

puted heavy

converge

o i l and the

preprocessor fails

to

In of

conversion To a s s i s t prints

out

converge:

feed property

change

occurred

a l l operating

time of

and was

estimates

any alternate FCC operation.

the

it

conversion per pass loop.

new estimates,

Identity

the

and feed perturbations, the

re

factors

discovered

ο

database.

selectivity

ο

ο

default

reactor

Twenty-seven unit parameters including

operations

final

unit and

feed rate

tested on alternate

this

the

including

temperature and fresh

actor

When the

the

constraints,

the base and alternate FCC operations:

ο

the

o i l cuts.

the base FCC feed composed of

Adjustment of

in

carbon in aromatic

the base mix along with a s p e c i f i e d f r a c t i o n

able.

and Rams-

derived from physical mea

distillation

assay cuts

feed in terms

the necessary properties

properties

crude

the

distillation,

two standard

cuts of

cutpoints

from the

vacuum gas

a description of gravity,

A l l of

crude

overhead.

The

447

molecular weight and percent

blended properties and

Programming

properties

cycloparaffin rings.

ported

Linear

The FCC Simulator To The Preprocessor

The


Refinery

A N D LiEDER

failure, cycle

and feed variables including

the

at

last-com

o i l endpoint and conversion

per pass

American Chemical Society Library 16th st. N. tow. Squires and Reklaitis;1155 Computer Applications Chemical Engineering ACS Symposium Series; American Chemical Washington, DC, 1980. Washington, D. C. Society: 20036

448

To

COMPUTER

avoid convergence

the

FCC simulator,

feed property

problems during

to

all

the values

CHEMICAL

ENGINEERING

feed perturbation runs of

we have made adjustments

change and reset

feed perturbation

APPLICATIONS TO

initial

to

the

size

of

each

estimates before

computed by the

simulator

each

for

the

base FCC operation. Linking

The Hydrocracker Simulator To The Preprocessor

The cut

feed

operation. each


to

the hydrocracker

consists

from the base crude mix and l i g h t of

in Table the

The hydrocracker

these feeds I.

Since

in

the heavy naphtha

o i l from the base FCC

requires

a description of

the hydrocarbon components shown

these components

crude assay nor are

special

simulator

terms of

of

cycle

are

not

d i r e c t l y measured

in

they predicted by the FCC simulator,

techniques were developed to

estimate

them from available

data. For lowing

the heavy naphtha cut technique

is

From each

1.

from the base crude mix,

used by the

weight, rings

crude assay,

per molecule are o i l cuts

These data are

2.

the

density,

and average aromatic

saturate and aromatic two gas

fol-

obtained for both

linearly

tillation

unit.

and

boiling

molecular

and c y c l o p a r a f f i n

fraction

distilled

heavy naphtha cut final

the

preprocessor:

in

the

of

the

to

the

crude

midpoint between

points

is

the

laboratory.

extrapolated

s p e c i f i e d for Again,

the

from each

disinitial

the independent

variable. 3.

Component mol fractions are

equations.

The equations

cycloparaffin

equations

relating

C o e f f i c i e n t s for

analytical

light

The the

change the

simulator also

operation

in

values

are of

stored any of

a

cor-

based on various carbon as is

in-

aromatic

based on mass

oils. requires

terms of

operating v a r i a b l e s ,

default values

computed for

These properties

and percent

The c o r r e l a t i o n

data on FCC cycle

hydrocracker

constraints, or

FCC simulator.

molecular weight,

unit and i t s

are

from the base mix.

o i l from the base FCC operation,

and c y c l o p a r a f f i n r i n g .

spectrometer

the em-

data on a number of

component mol fractions

computed by the

clude density, ring

cycle the

distribution

feeds.

the heavy naphtha cut predicts

and

as em-

equations were derived from mass

Blended component fractions

4.

properties

ring

cut

of

aromatic

average.

ring

a set

as well

to

spectrometer

the

include

r i n g balances

v i r g i n hydrocracker

For

each heavy naphtha

pirical pirical

relation

in

then determined by solution of

in the

a description of

equipment dimensions and

and unit parameters.

the

preprocessor.

following

in

Standard

The user

specifying

can

the base


25.

Refinery

P O L L A C K A N D LiEDER

Linear

TABLE

Programming

I

HYDROCARBON COMPONENTS RECOGNIZED BY HYDROCRACKER SIMULATOR

Hydrogen Methane


Ethane Propane i/n

Butanes

C /C 5

Paraffins

6

Benzene Methylcyclopentane C

7

-

C

Paraffins

1 2

Single Ring Cycloparaffins Single Ring Aromatics

C

13

+

P

a

r

a

f

f

i

n

s

Double Ring Cycloparaffins Double Ring Aromatic Cycloparaffins Double Ring Aromatics Multi

Ring Cycloparaffins

Multi

Ring Aromatic Cycloparaffins

Multi

Ring Aromatics


449

450

COMPUTER

and

alternate

APPLICATIONS TO

CHEMICAL

ENGINEERING

operations:

ο

Eight

operating variables

version per pass ο

Five unit

including

con

and feed rate

parameters

including

metal and acid a c t i v i t i e s

catalyst

in

both

re

actors ο No cracker of


Linking

and feed property

simulator also

Fortunately,

most of

crude assay and are For

(1)

crude,

distillation of

boiling

determines

at

(3)

For

the

tributes

for

overhead for for

the

crude

each naphtha the compo initial

and f i n a l

the blended compositions of

the

from the base crude mix. hydrocrackates,

the hydrocracker

a product f r a c t i o n a t i o n subroutine which

components between adjacent

Fenske-type

the

component present

specified

remaining between the

the heavy and l i g h t includes

each

fraction d i s t i l l e d

and ( 4 ) computes

motor and BTX naphthas simulator

from the base crude mix,

the amount of

constructs

the material

points,

the

shown in

these components are measured in

the naphtha cutpoints

unit,

These are

predicted by the hydrocracker simulator.

( 2 ) computes

component

sition

changes.

requires a description of

the motor and BTX naphthas

preprocessor the

the hydro-

and running on a wide range

terms of hydrocarbon components.

Table I I .

in

the preprocessor

operations

reformer

in

each

factors

The Reformer Simulator To The Preprocessor

The

the

steam and operating cost

problems were found in l i n k i n g

simulator to

alternate

feed

Fuel,

convergence

fractionator

cuts

dis

using a

formulation.

Standard or operations

are

the values

of

default values

stored any of

in

for

the motor and BTX reforming

the preprocessor.

the

following

in

The user

specifying

can change

the base or any

alternate operation: ο

Six operating variables former,

nine

for

cluding

target

for

the motor

the BTX reformer,

reformate

re in

octane and feed

rate ο

Three unit acid

parameters

activities

idealized ο

Fuel,

of

including metal and the

catalyst

in

the

single reactor

steam,

operating cost,

and capacity

factors To loops the

speed the operation of

in

inner

fractions It

the

linked

loop,

after

of

and heavier

was found

C4

that

are

assumed to

the

rate of

of

the

reformer

the

a certain in

number of the

s l i g h t variations

react

in

the

preprocessor,

the

convergence

simulator have been modified. recycle in

iterations, gas

are

In

the mole

held

constant.

these components (which

reforming k i n e t i c

model)

convergence without materially improving

slowed down the

results.


accuracy

Refinery

P O L L A C K A N D LiEDER

TABLE

Linear

Programming

II

HYDROCARBON COMPONENTS RECOGNIZED BY


REFORMER SIMULATOR

Hydrogen

Toluene

Methane

C3

Ethane

Cg Cycloparaffins

Propane

Cg Aromatics

i-Butane

C9

Paraffins

n-Butane

C9

Cycloparaffins

Cg

Aromatics

Pentanes +

Cyclopentane

Hexanes

C"LO

Cyclohexane

c

Me thyIcyclopentane

Paraffins

Paraffins

10

c

C^Q

y

c

l ° P

a

r

a

f

f

i

n

s

Aromatics

Benzene

c

Heptanes

Cn+

Cycloparaf f i n s

Methylcyclohexane

C +

Aromatics

C7

l l

n Ί

+

Paraffins

Cyclopentanes


452

COMPUTER

For

the outer

loop,

the preprocessor

erature by secant method to Structure The

the

adjusts

target

ENGINEERING

isothermal temp

octane.

generates

the

following

activities

in

the

LP matrix: Activities

1.

matrix and

in five

preserve

crude

lation

distillation

incremental crude operations. properties

for downstream

or product blending,

cuts

unit sub-

the base crude mix operation

their

processing enter

the

represent

up to

To


satisfy

CHEMICAL

Of The Preprocessor-Generated LP Model preprocessor

refinery

APPLICATIONS TO

from each

the

crude unit

separate and d i s t i n c t

distil

activity

stream balance

rows. Activities

2.

unit

in

the

propane deasphalting (PDA)

submatrix represent

vacuum tower bottoms and

from the

asphalter enter

incremental crudes.

Each deasphalter

arate row for No. 6 f u e l Activities

3.

and

in

feed

transfers

process

crude

For cients

the

following

enter a sep

of

motor

represent (1)

the

crude operations

operations,

material

(2)

units

simulating cutpoint, (3) and (4)

changes

feed property.

these a c t i v i t i e s , in

bottoms

o i l blending.

distillation

base and alternate in each

common prop

units,

between process in

activities

row with

submatrices

streams from each from other

a change

The de-

the FCC, hydrocracker,

BTX reformer

and

operations on

overhead streams from a l l

one stream balance

erties.

the

from the base crude mix

the

preprocessor

computes

coeffi

refinery LP rows:

ο

Fuel

ο

Operating

and steam balance rows

ο

Equipment usage rows l i m i t i n g

ο

Stream balance rows

ο

Property blending

cost row equipment capacity

rows to meet product

specifi

cations In

addition,

(FCC,

for

each of

hydrocracker,

generates a set

of

these rows and the that

the unit

distillation To

performance can respond to as well

of

how

this

is

as

changes

process

the

rows.

corresponding feed property

feed from other

see

structure

feed property balance

cutpoint

portion of

the major downstream processing units

motor and BTX reformers),

is

through

change

changes in

preprocessor

It in

activities

crude mix and

properties

or

pro

units.

accomplished, l e t

a downstream processing unit

us examine submatrix

the

general

(Figure 6 ) .



STREAM

ROWS

C O S T OR U S A G E

ROWS

BALANCE

STREAM

ROWS

BALANCE

PROPERTY

ROW

VOLUME

BALANCE

UNIT

ROWS

BALANCE

-P

Linking Process Simulators to a Refinery Linear Programming Model

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