Enterprisewide optimization of integrated planning and scheduling for refinerypetrochemical complex with heuristic algorithm
Lifeng Zhang, Haoyang Hu, Zhiquan Wang, Zhihong Yuan, Bingzhen Chen
Enterprisewide optimization of integrated planning and scheduling for refinerypetrochemical complex with heuristic algorithm
This paper focuses on the integrated problem of longterm planning and shortterm scheduling in a largescale refinerypetrochemical complex, and considers the overall manufacturing process from the upstream refinery to the downstream petrochemical site. Different time scales are incorporated from the planning and scheduling subproblems. At the end of each discrete time period, additional constraints are imposed to ensure material balance between different time scales. Discrete time representation is applied to the planning subproblem, while continuous time is applied to the scheduling of ethylene cracking and polymerization processes in the petrochemical site. An enterprisewide mathematical model is formulated through mixed integer nonlinear programming. To solve the problem efficiently, a heuristic algorithm combined with a convolutional neural network (CNN), is proposed. Binary variables are used as the CNN input, leading to the integration of a datadriven approach and classical optimization by which a heuristic algorithm is established. The results do not only illustrate the detailed operations in a refinery and petrochemical complex under planning and scheduling, but also confirm the high efficiency of the proposed algorithm for solving largescale problems.
planning / scheduling / refinerypetrochemical / convolutional neural network / heuristic algorithm
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Main units in refinery and petrochemical
Unit  Abbreviation 

Refinery units  
Delayed coking unit  DCU 
Wax oil hydrotreating unit  WHU 
Hydrocracking unit  HDT 
Catalytic cracking unit  CCU 
Coking naphtha hydrotreating unit  CNHT 
Naphtha hydrotreating unit  NHT 
Dry liquefied gas desulfurization unit  LDU 
Liquefied gas separation unit  LSU 
Dry gas separation unit A  DSU A 
Continuous reformer  CRU 
Aromatics complex  ARU 
Naphtha nisomer separation unit  NSU 
Jet fuel hydrogenation unit  JHT 
Diesel hydrocracking unit A  DHT A 
Diesel hydrocracking unit B  DHT B 
Gas fractionation unit  GFU 
Alkylation unit  AKU 
Hydrogen deep recovery device  HDRU 
Hydrogen recovery unit  HRU 
Dry gas separation unit B  DSU B 
Catalytic gasoline hydrogenation unit  CHU 
Jet fuel hydrogenation unit  JHT 
Coke hydrogen production unit  CHP 
Sulfur recovery unit  SRU 
Petrochemical units  
Gasoline hydrogenation unit  GHT 
Butadiene extraction unit  BEU 
MTBE/butene1 unit  MTBE 
Styrene unit  STU 
Full density polyethylene unit  FDPE 
Acrylonitrile butadiene styrene unit  ABS 
Acetonitrile unit  ATU 
methyl methacrylate unit  MMA 
Acrylonitrile polymerization unit  APU 
High density polyethylene unit  HDPE 
Polypropylene unit  PP 
Main products from refinery and petrochemical
Refinery product  Petrochemical product  

92# gasoline  Pitch  C5  C9+ 
95# gasoline  PX  Propylene  Butadiene 
98# gasoline  Petroleum coke  Styrene  MMA 
Jet fuel  Butane  Acetonitrile  Acrylonitrile 
Diesel  Sulfur  LLDPE  HDPE 
Liquefied petroleum gas (LPG)  Ammonia  PP  
Benzene  Fuel oil  
Methylbenzene (PhMe) 
C  Set for crude distillation units 
O  Set for crude oils 
T  Set for time periods 
N  Set for time plots in scheduling of ethylene cracking 
J  Set for time plots in scheduling of polymerization process 
S  Set for stream 
R  Set for raw materials 
U  Set for processing units 
M  Set for operation modes 
I  Set for intermediate stream tanks 
P  Set for products 
K  Set for cracking furnaces 
Q  Set for polymerization reactors 
L  Set for polymer products 
G  Set for grades of polymer products 
${X}_{p,t}$  Price of product p at time t 
${X}_{q,l,g,t}$  Price of grade g in polymer l from reactor q at time t 
${X}_{c,o,t}$  Price of crude oil o for CDU c at time t 
${X}_{r,t}^{\mathrm{p}\mathrm{u}\mathrm{r}}$  Price of raw material r at time t 
${V}_{c,o}^{\mathrm{i}\mathrm{n}\mathrm{v}}$  Inventory cost of crude oil o in CDU c 
${V}_{p}^{\mathrm{i}\mathrm{n}\mathrm{v}}$  Inventory cost of product p 
${V}_{q,l,g}^{\mathrm{i}\mathrm{n}\mathrm{v}}$  Inventory cost of grade g in polymer l from reactor q 
${V}_{c,o}^{\mathrm{p}\mathrm{r}\mathrm{o}}$  Process cost of crude oil o in CDU c 
${V}_{u}^{\mathrm{o}\mathrm{p}}$  Operation cost of unit u 
${V}_{k}^{\mathrm{o}\mathrm{p}}$  Operation cost of furnace k 
${V}_{q}^{\mathrm{o}\mathrm{p}}$  Operation cost of reactor q 
${V}_{k}^{\mathrm{c}\mathrm{n}}$  Clean up cost of furnace k 
${V}_{i,ii,k}^{\mathrm{c}\mathrm{h}}$  Changeover cost from intermediate i to ii in furnace k 
${V}_{q,l,g,{g}^{\prime}}^{\mathrm{c}\mathrm{h}}$  Changeover cost from grade g to g' in polymer l from reactor q 
${A}_{c}^{\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum capacity of CDU c 
${A}_{c}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum capacity of CDU c 
${V}_{c,o}^{\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum purchase amount of crude oil o to CDU c 
${V}_{c,o}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum purchase amount of crude oil o to CDU c 
${I}_{c,o}^{0}$  Initial inventory of crude oil o to CDU c 
${I}_{c,o}^{\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum inventory of crude oil o to CDU c 
${I}_{c,o}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum inventory of crude oil o to CDU c 
${x}_{c,o,s}^{\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum cut point for stream s of crude oil o from CDU c 
${x}_{c,o,s}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum cut point for stream s of crude oil o from CDU c 
${a}_{r,u}$  Constant inlet ratio of raw material r to unit u 
${A}_{u}^{\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum capacity of unit u 
${A}_{u}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum capacity of unit u 
${x}_{u,m,s}^{\mathrm{f}\mathrm{i}\mathrm{x}\mathrm{e}\mathrm{d}}$  Constant yield of stream s in mode m in unit u 
${I}_{i}^{0}$  Initial inventory of intermediate i 
$H$  Time length of each time period 
${F}_{i,k,n,t}^{\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{e},\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum flowrate of intermediate i to furnace k in slot n at time t 
${F}_{i,k,n,t}^{\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{e},\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum flowrate of intermediate i to furnace k in slot n at time t 
${T}_{k,n,t}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum operation time for furnace k in slot n at time t 
${a}_{i,k,s}$  Coefficient of yield of stream s from intermediate i in furnace k 
${b}_{i,k,s}$  Coefficient of yield of stream s from intermediate i in furnace k 
${c}_{i,k,s}$  Coefficient of yield of stream s from intermediate i in furnace k 
${x}_{q,l,g}^{\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum yield of grade g of polymer l from reactor q 
${x}_{q,l,g}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum yield of grade g of polymer l from reactor q 
${T}_{q,l,g,{g}^{\prime}}^{\mathrm{c}\mathrm{h}\mathrm{a},\mathrm{f}\mathrm{i}\mathrm{x}\mathrm{e}\mathrm{d}}$  Constant changeover time from grade g to g' of polymer l in reactor q 
${A}_{q}^{\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{e},\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum capacity of reactor q 
${A}_{q}^{\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{e},\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum capacity of reactor q 
${d}_{q.l,g,t}^{\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum demand of grade g of polymer l from reactor q at time t 
${d}_{q,l,g,t}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum demand of grade g of polymer l from reactor q at time t 
${d}_{p,t}^{\mathrm{m}\mathrm{i}\mathrm{n}}$  Minimum demand of product p at time t 
${d}_{p,t}^{\mathrm{m}\mathrm{a}\mathrm{x}}$  Maximum demand of product p at time t 
${y}_{c,o,t}^{\mathrm{p}\mathrm{u}\mathrm{r}}$  Purchase decision of crude oil o for CDU c at time t 
${y}_{c,o,t}^{\mathrm{p}\mathrm{r}\mathrm{o}}$  Process decision of crude oil o for CDU c at time t 
${y}_{u,m,t}^{\mathrm{m}\mathrm{o}\mathrm{d}\mathrm{e}}$  Assignment of operation mode m to unit u at time t 
${y}_{i,k,n,t}^{\mathrm{a}\mathrm{s}\mathrm{s}\mathrm{i}}$  Assignment of intermediate i to furnace k in plot n at time t 
${y}_{i,ii,k,n,t}^{\mathrm{c}\mathrm{h}}$  Assignment of changeover from intermediate i to ii for furnace k in plot n at time t 
${y}_{k,n,t}^{\mathrm{c}\mathrm{n}}$  Assignment of clean up operation to furnace k in plot n at time t 
${y}_{q,l,g,j,t}^{\mathrm{a}\mathrm{s}\mathrm{s}\mathrm{i}}$  Assignment of grade g to polymer l from reactor q in plot j at time t 
${y}_{q,l,g,{g}^{\prime},j,t}^{\mathrm{c}\mathrm{h}}$  Assignment of changeover from grade g to g' of polymer l from reactor q in plot j at time t 
z  Total profit as the objective function 
${F}_{c,o,t}^{\mathrm{p}\mathrm{r}\mathrm{o}}$  Process flowrate of crude oil o for CDU c at time t 
${F}_{c,o,t}^{\mathrm{p}\mathrm{u}\mathrm{r}}$  Purchase amount of crude oil o for CDU c at time t 
${I}_{c,o,t}$  Inventory amount of crude oil o for CDU c at time t 
${x}_{c,o,s,t}$  Cut point of stream s from crude oil o for CDU c at time t 
${x}_{c,o,s,t}$  Yield value of stream s from crude oil o for CDU c at time t 
${F}_{c,s,t}^{\mathrm{o}\mathrm{u}\mathrm{t}}$  Outlet flowrate of stream s from CDU c at time t 
${F}_{c,s,u,t}$  Outlet flowrate of stream s from CDU c to unit u at time t 
${F}_{c,s,p,t}$  Outlet flowrate of stream s from CDU c to product p at time t 
${F}_{u,t}^{\mathrm{i}\mathrm{n}}$  Inlet flowrate to unit u at time t 
${F}_{i,u,t}$  Outlet flowrate of intermediate i to unit u at time t 
${F}_{r,u,t}$  Outlet flowrate of raw material r to unit u at time t 
${F}_{{u}^{\prime},s,u,t}$  Outlet flowrate of stream s from unit u’ to unit u at time t 
${F}_{u,m,t}^{\mathrm{i}\mathrm{n}}$  Inlet flowrate to mode m in unit u at time t 
${F}_{u,s,t}^{\mathrm{o}\mathrm{u}\mathrm{t}}$  Outlet flowrate of stream s from unit u at time t 
${F}_{u,s,p,t}$  Outlet flowrate of stream s from unit u to product p at time t 
${F}_{u,s,i,t}$  Outlet flowrate of stream s from unit u to intermediate i at time t 
${I}_{i,t}$  Inventory amount of intermediate i at time t 
${F}_{k,s,i,t}$  Outlet flowrate of stream s from furnace k to intermediate i at time t 
${F}_{i,k,t}$  Outlet flowrate of intermediate i to furnace k at time t 
${F}_{i,q,j,t}$  Outlet flowrate of intermediate i to reactor q in slot j at time t 
${T}_{k,n,t}^{\mathrm{s}\mathrm{t}}$  Start time of slot n in furnace k at time t 
${T}_{k,n,t}^{\mathrm{e}\mathrm{n}\mathrm{d}}$  End time of slot n in furnace k at time t 
${T}_{k,n,t}^{\mathrm{d}\mathrm{u}\mathrm{r}}$  Duration time of slot n in furnace k at time t 
${T}_{k,n,t}^{\mathrm{o}\mathrm{p}\mathrm{e}}$  Total operation time for furnace k in slot n at time t 
${F}_{i,k,n,t}^{\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{e}}$  Outlet flowrate of intermediate i to furnace k in slot n at time t 
${x}_{i,k,s,n,t}$  Yield of stream s from intermediate i in furnace k in slot n at time t 
${F}_{k,s,n,t}^{\mathrm{o}\mathrm{u}\mathrm{t}}$  Outlet flowrate of stream s from furnace k in slot n at time t 
${T}_{q,j,t}^{\mathrm{s}\mathrm{t}}$  Start time of slot j in reactor q at time t 
${T}_{q,j,t}^{\mathrm{e}\mathrm{n}\mathrm{d}}$  End time of slot j in reactor q at time t 
${T}_{q,j,t}^{\mathrm{d}\mathrm{u}\mathrm{r}}$  Duration time of slot j in reactor q at time t 
${x}_{q,l,g,j,t}$  Yield of grade g in polymer l in reactor q in slot j at time t 
${T}_{q,j,t}^{\mathrm{c}\mathrm{h}\mathrm{a}}$  Changeover time of reactor q in slot j at time t 
${F}_{q,j,t}^{\mathrm{i}\mathrm{n}}$  Inlet flowrate to reactor q in slot j at time t 
${F}_{r,q,j,t}$  Inlet flowrate to reactor q from raw material r in slot j at time t 
${F}_{q,l,g,j,t}^{\mathrm{o}\mathrm{u}\mathrm{t}}$  Outlet flowrate of grade g in polymer l from reactor q in slot j at time t 
${F}_{q,l,g,t}^{\mathrm{s}\mathrm{a}\mathrm{l}\mathrm{e}}$  Sale amount of grade g in polymer l from reactor q at time t 
${I}_{q,l,g,t}$  Inventory amount of grade g in polymer l from reactor q at time t 
${F}_{p,t}^{\mathrm{s}\mathrm{a}\mathrm{l}\mathrm{e}}$  Sale amount of product p at time t 
${I}_{p,t}$  Inventory amount of product p at time t 
/
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