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A Computerised Bin Data Monitoring System at a Polyethylene Manufacturing Facility
Copyright
© IFAC PRP 4 Automation. Ghent . Bdgium 1980
A COMPUTERIZED BIN DATA MONITORING SYSTEM AT A POLYETHYLENE MANUFACTURING FACILITY L. Chauvin Process Computer Department, BP Chemicals, Zwijndrecht, Belgium
Abstract. With the emphasis towards decentralisation of computing power and hence, moving the computer to the locations where data is generated, e.g. the production units, a renewed approach of the data processing needs for operational management becomes possible. The computer complex installed at the LOPE-unit of the BP Chemicals' Plant in Antwerp is designed to perform, in addition to the data acquisition, logging, alarming and on-line supervisory controls for reaction- and recovery-systems several management information system U~. I .S.) functions. The Bin Data tlonitoring System illustrates very clearly the potentials of on-line data handling functions in the Inventory Recording, Reactor Operator Guidance and Quality Control fields. Keywords. Digital Computer Applications; Plastics Industry; Quality Control; Management Information Systems.
INTRODUCT ION
Several of these operations are strongly supported by computer applications:
Historically, the prime objectives of implementing mini-<:omputers in the BP Chemicals' Plant in Antwerp were Process Monitoring and Control, focussing all technological efforts on improvement of oroduction. Standard functions included: Data Acquisition, Logging, Alarming and OnLine Supervisory Control.
Production Low density polyethylene pellets produced in the 2 high pressure tube reactors are directly transferred to a total of 18 storage bins: 8 primary bins and 10 blend bins, offering a storage capacity of 1 200 tons, which corresponds to a 2 days production buffer.
However, even with the first applications, it was felt that a computer system could also considerably contribute to optimise the efficiency of operational management tasks.
In addition to the loading operations, several bin-to-bin transfers can be initiated subject to quality control decisions . After blending, the resin is loaded into containers with a standard weight of 20 tons.
The Bin Data ~lonitoring System is a typical example of this actual trend toward~ Management Information Systems. THE MANUFACTURING CYCLE AND CONTROL
Starting from these base resins, a wide range of homopolymer products can be obtained by routing them through the compounding facilities. The product mi x contains products such as ocean cable, wire and cable, pipe, film and extrusion coating grades .
Essentially, the manufacturing cycle consists of following operations : Product Requirement Planning, Production Scheduling, Production, Quality Control, Inventory Control and Sales Administration . A closed loop data-flow relates each function to the others. (Fi g. 1)
Computer support is focus sed on Production Monitoring and Process Control. 377
L. Chauvin
378
Data acquisition, logging, alarming and automatic production reporting are standard features. Reaction- and Recovery Processes are covered by on-line supervisory control systems including automatic reactor start-up and transition control from one resin grade to another. Compounding operations, resin transfers and container loading operations are monitored/ controlled by programmable controllers (PLC 's).
~.,.
, ROD U C T
Inventory Control, Sales Administration Base resins are stored in Endproducts are packaged, customer requirements and in containers, holbins or
containers. subject to product quality, bags.
Recent expansions of the process computer system are aimed at real-time inventoryrecording and automatisation of sales administration tasks: both the Van Box Monitoring System and the Packaged Stock Control System offer on-line commercial and physical product-availability status reports . These systems contain information for up to 1 000 containers and 3 000 lots of bags and holbins.
1£OU:1EIt£!lT , L A If fII r 11 Si
THE BIN DATA MONITORING SYSTEM
<& , ADD U c r I S C.H £ 0 U L. t
Q
N
/11
I)
,,!I,. "ODUCTIO"
~ c:::J
-
~ o 11
... l I T Y
CO" T • 0 L
FUTURE EXP",.SIO"S
=PIIIODUCTlON HOIUTOU"6: DATA ACQUJSlTIOII. LOGGING - pqOCESS COIITROl DIf-LHlE SUHUISDIY CONnOL a
o"
I
• I • o A. T A r 0 1 I fII , S 't S T [
....
-1, v,. . . -i p'e"",
1"
~~ I 11 V E If T 0 III ., COIITlaL.
" 0 If ITa III I fII Iii
CO" T 11 0 l
~7 5 ALE S
AO"IMJSTRATIOII
....
Fig. 1.
Reactor Operator Guidance
,T,e, S" 5 T E If
FUTURE [xPAltSIOft5
~ C 0 liII
OPE" A 7 I 'l" 5
~
t;
The Bin Data Monitoring Package illustrates this multilateral nature: this function provides Reactor Operator Guidance, Inventory Recording and Quality Control of both reaction and blending operat ions .
S Y 5 T E fit
c= C=:J
Most M.I.S. computer applications cover simultaneously several operational function~ perhaps this "hybrid" nature is the most important factor in explaining the impact of these apolications on the efficiency of operational management tasks.
T E iI:
F U " C 7 I 0 III S
The manufacturing Control Cycle.
Qua 1i ty Control During production, resin samples are taken on a cyclic basis to the Qua lity Control Laboratory for analysis . As a rigorous quality control scheme i s imperative for pol yethylene production processes, an instant feedback of all laboratory results is mandatory. Initially, communications between Laboratory and Production Control Rooms were performed by Telewriters, a rather cumbersome and inefficient system in day-to-day operations. In order to standardise and speed-up these communications the Bin Data Monitoring Package was implemented on the existing process computer system.
While filling the inventory bins, each laboratory analysis result must be timely and accurately transmitted to the reaction operators. The Bin Data Monitor ing System is designed to operate in dialogue mode through the use of CRT-Op Conso le s. It is totally accessible for Laboratory Technicians, Production Operators and Plant Accounting Personnel, thus providing a direct communication link between these departments. The laboratory technician enters, for each anal ysis, all relevant data via the CRT-Op console keyboard: entries comprise analysis identification codes, date and time of sampling and the actual laboratory measurements. Fifteen different properties can be handled ranging from melt inde x, density up to filmrating, gloss and pellet sizes. The corresponding inputs can be numeric values as well as predetermined codes. Ease of use was emphasized through the design of the package . A typical example of this is the conversational aspect of data entry : each user can, in function of his familiarity with the system, select a "full dialogue" or a "short cut" mode for data input. The "full dialogue" mode leads the operator through a series of
A Computerised Bin Data Monitoring System
question/answer steps until all information is entered. The "short cut" mode enables the operator to enter all data in a compressed format. The system completes the entry by providing a real-time character to the analysis: with each input a weight is associated, giving the amount of resin produced corresponding to that particular sample. These weights are determined by continuous monitoring of the weigh cells of each bin. On each input a conforming message comDrising all relevant data is printed at all locations: Reactor Control Room, Laboratory, Container Loading Stations and Product Room; thus assuring an instant and standardised distribution of all quality control information. By storing all lab . -measurements on disc, the system is able to calculate at any moment a so-called "Blending Average" giving the averages of all available measured resin properties. Furthermore, these calculations can be extended to determine, starting from the lab.-measurements of a partially filled bin, the required "run"-values to be used for the production of the remaining resin in order to finish the total bin within aim specifications: a true operator guidance tool. Inventory Recording As not only the loading/unloading but also the transfers between the bins are monitored, a complete on-line follow-up of all resin is realised. At any moment, an operator can request a Bin Report specifying the actual weights of resin stored together with a summary of all measured properties . (Fig. 2) These reports are automatically printed at the start of each production shift, giving a total inventory record overview. Qua 1i ty Control The Blend Reports provide a very effective means of checking the quality of the physical blending operations: the deviations between sample analysis of the blended product and the calculated.averag~s .give an indication of the blendlng efflclency.
•
: 11
• E " 0 • T
IU:
1127
IUI: lUll TYPE: QUALITT:
OUll
TOTAL IIUGMT;
95711. KO
379
T t III [:
11.51
OAT E:
27/11/79
UZ
Al" ILUOllle AV' P'EASUUD I
ILUOUC AVIii ,CALCULATEDl N[LT IIOU :
0 . 17 PELLET SIlt : C 'ILII urINe: 110 DUSITY: C. UID
0.17
O. UZO
LAI . NUSUROUTS NI:
ps:
"1:
OY :
Fig. 2.
TtNE
DATt
1' : 21 1, , 17 20 : 47 23:01 0:32 Z:lZ 4:46
26/11 2'/11 2"11 25111 27/11 27/ll 21/11
n"[
DATE
11 : 2.
%SIll
16001S
20 : 47
26/11 27/11
2000/S
O: lZ 4:46
27 / 11
410/C
TINE
OATE
U.lLTSIS
VALUE
16:29
HIll
20:41 0:33 4 : 46
21111
16001S 2000/S 2400/C
80 80 80 80
TIME
DATE
Ol :05
27/11
26/11
27/11
"MALTS IS 1I00/S 15001S 2000/S %200/S lIOO/C 0200/S
VALUE 0 . 16 0 . 17 0.11 0.17
0.17 0.11
O'lO/C
0.11
ANALYSIS
VALUE
0410/C
2200 / 5
13820 11500 9000 13320 8700 12000 13100 'EI'HT ( lG) 13820. 25500
HOO/C
ANALfSlS
ilUliHT (lli)
lUtO ZSSOD
VALUE
o ,9Z10
WEIGHT (KC)
lJI20
25500 ZZZZO
25500 W£IGHT
(KG )
7U4Q
Bin Report. CONCLUSIONS
Distributed on-line handling systems, providing both Droduction and distribution departments a direct and easy access to vital production information, are very powerful management tools for the . optimization of the overall manufacturlng operations . It has been demonstrated that Plant Mananement Information Systems, developed arou~d a mini-computer network, are both effective and economically justifiable for the daily operations. Indicative to this fact is the ever expanding scope of such applications within our company.
© IFAC PRP 4 Automation. Ghent . Bdgium 1980
A COMPUTERIZED BIN DATA MONITORING SYSTEM AT A POLYETHYLENE MANUFACTURING FACILITY L. Chauvin Process Computer Department, BP Chemicals, Zwijndrecht, Belgium
Abstract. With the emphasis towards decentralisation of computing power and hence, moving the computer to the locations where data is generated, e.g. the production units, a renewed approach of the data processing needs for operational management becomes possible. The computer complex installed at the LOPE-unit of the BP Chemicals' Plant in Antwerp is designed to perform, in addition to the data acquisition, logging, alarming and on-line supervisory controls for reaction- and recovery-systems several management information system U~. I .S.) functions. The Bin Data tlonitoring System illustrates very clearly the potentials of on-line data handling functions in the Inventory Recording, Reactor Operator Guidance and Quality Control fields. Keywords. Digital Computer Applications; Plastics Industry; Quality Control; Management Information Systems.
INTRODUCT ION
Several of these operations are strongly supported by computer applications:
Historically, the prime objectives of implementing mini-<:omputers in the BP Chemicals' Plant in Antwerp were Process Monitoring and Control, focussing all technological efforts on improvement of oroduction. Standard functions included: Data Acquisition, Logging, Alarming and OnLine Supervisory Control.
Production Low density polyethylene pellets produced in the 2 high pressure tube reactors are directly transferred to a total of 18 storage bins: 8 primary bins and 10 blend bins, offering a storage capacity of 1 200 tons, which corresponds to a 2 days production buffer.
However, even with the first applications, it was felt that a computer system could also considerably contribute to optimise the efficiency of operational management tasks.
In addition to the loading operations, several bin-to-bin transfers can be initiated subject to quality control decisions . After blending, the resin is loaded into containers with a standard weight of 20 tons.
The Bin Data ~lonitoring System is a typical example of this actual trend toward~ Management Information Systems. THE MANUFACTURING CYCLE AND CONTROL
Starting from these base resins, a wide range of homopolymer products can be obtained by routing them through the compounding facilities. The product mi x contains products such as ocean cable, wire and cable, pipe, film and extrusion coating grades .
Essentially, the manufacturing cycle consists of following operations : Product Requirement Planning, Production Scheduling, Production, Quality Control, Inventory Control and Sales Administration . A closed loop data-flow relates each function to the others. (Fi g. 1)
Computer support is focus sed on Production Monitoring and Process Control. 377
L. Chauvin
378
Data acquisition, logging, alarming and automatic production reporting are standard features. Reaction- and Recovery Processes are covered by on-line supervisory control systems including automatic reactor start-up and transition control from one resin grade to another. Compounding operations, resin transfers and container loading operations are monitored/ controlled by programmable controllers (PLC 's).
~.,.
, ROD U C T
Inventory Control, Sales Administration Base resins are stored in Endproducts are packaged, customer requirements and in containers, holbins or
containers. subject to product quality, bags.
Recent expansions of the process computer system are aimed at real-time inventoryrecording and automatisation of sales administration tasks: both the Van Box Monitoring System and the Packaged Stock Control System offer on-line commercial and physical product-availability status reports . These systems contain information for up to 1 000 containers and 3 000 lots of bags and holbins.
1£OU:1EIt£!lT , L A If fII r 11 Si
THE BIN DATA MONITORING SYSTEM
<& , ADD U c r I S C.H £ 0 U L. t
Q
N
/11
I)
,,!I,. "ODUCTIO"
~ c:::J
-
~ o 11
... l I T Y
CO" T • 0 L
FUTURE EXP",.SIO"S
=PIIIODUCTlON HOIUTOU"6: DATA ACQUJSlTIOII. LOGGING - pqOCESS COIITROl DIf-LHlE SUHUISDIY CONnOL a
o"
I
• I • o A. T A r 0 1 I fII , S 't S T [
....
-1, v,. . . -i p'e"",
1"
~~ I 11 V E If T 0 III ., COIITlaL.
" 0 If ITa III I fII Iii
CO" T 11 0 l
~7 5 ALE S
AO"IMJSTRATIOII
....
Fig. 1.
Reactor Operator Guidance
,T,e, S" 5 T E If
FUTURE [xPAltSIOft5
~ C 0 liII
OPE" A 7 I 'l" 5
~
t;
The Bin Data Monitoring Package illustrates this multilateral nature: this function provides Reactor Operator Guidance, Inventory Recording and Quality Control of both reaction and blending operat ions .
S Y 5 T E fit
c= C=:J
Most M.I.S. computer applications cover simultaneously several operational function~ perhaps this "hybrid" nature is the most important factor in explaining the impact of these apolications on the efficiency of operational management tasks.
T E iI:
F U " C 7 I 0 III S
The manufacturing Control Cycle.
Qua 1i ty Control During production, resin samples are taken on a cyclic basis to the Qua lity Control Laboratory for analysis . As a rigorous quality control scheme i s imperative for pol yethylene production processes, an instant feedback of all laboratory results is mandatory. Initially, communications between Laboratory and Production Control Rooms were performed by Telewriters, a rather cumbersome and inefficient system in day-to-day operations. In order to standardise and speed-up these communications the Bin Data Monitoring Package was implemented on the existing process computer system.
While filling the inventory bins, each laboratory analysis result must be timely and accurately transmitted to the reaction operators. The Bin Data Monitor ing System is designed to operate in dialogue mode through the use of CRT-Op Conso le s. It is totally accessible for Laboratory Technicians, Production Operators and Plant Accounting Personnel, thus providing a direct communication link between these departments. The laboratory technician enters, for each anal ysis, all relevant data via the CRT-Op console keyboard: entries comprise analysis identification codes, date and time of sampling and the actual laboratory measurements. Fifteen different properties can be handled ranging from melt inde x, density up to filmrating, gloss and pellet sizes. The corresponding inputs can be numeric values as well as predetermined codes. Ease of use was emphasized through the design of the package . A typical example of this is the conversational aspect of data entry : each user can, in function of his familiarity with the system, select a "full dialogue" or a "short cut" mode for data input. The "full dialogue" mode leads the operator through a series of
A Computerised Bin Data Monitoring System
question/answer steps until all information is entered. The "short cut" mode enables the operator to enter all data in a compressed format. The system completes the entry by providing a real-time character to the analysis: with each input a weight is associated, giving the amount of resin produced corresponding to that particular sample. These weights are determined by continuous monitoring of the weigh cells of each bin. On each input a conforming message comDrising all relevant data is printed at all locations: Reactor Control Room, Laboratory, Container Loading Stations and Product Room; thus assuring an instant and standardised distribution of all quality control information. By storing all lab . -measurements on disc, the system is able to calculate at any moment a so-called "Blending Average" giving the averages of all available measured resin properties. Furthermore, these calculations can be extended to determine, starting from the lab.-measurements of a partially filled bin, the required "run"-values to be used for the production of the remaining resin in order to finish the total bin within aim specifications: a true operator guidance tool. Inventory Recording As not only the loading/unloading but also the transfers between the bins are monitored, a complete on-line follow-up of all resin is realised. At any moment, an operator can request a Bin Report specifying the actual weights of resin stored together with a summary of all measured properties . (Fig. 2) These reports are automatically printed at the start of each production shift, giving a total inventory record overview. Qua 1i ty Control The Blend Reports provide a very effective means of checking the quality of the physical blending operations: the deviations between sample analysis of the blended product and the calculated.averag~s .give an indication of the blendlng efflclency.
•
: 11
• E " 0 • T
IU:
1127
IUI: lUll TYPE: QUALITT:
OUll
TOTAL IIUGMT;
95711. KO
379
T t III [:
11.51
OAT E:
27/11/79
UZ
Al" ILUOllle AV' P'EASUUD I
ILUOUC AVIii ,CALCULATEDl N[LT IIOU :
0 . 17 PELLET SIlt : C 'ILII urINe: 110 DUSITY: C. UID
0.17
O. UZO
LAI . NUSUROUTS NI:
ps:
"1:
OY :
Fig. 2.
TtNE
DATt
1' : 21 1, , 17 20 : 47 23:01 0:32 Z:lZ 4:46
26/11 2'/11 2"11 25111 27/11 27/ll 21/11
n"[
DATE
11 : 2.
%SIll
16001S
20 : 47
26/11 27/11
2000/S
O: lZ 4:46
27 / 11
410/C
TINE
OATE
U.lLTSIS
VALUE
16:29
HIll
20:41 0:33 4 : 46
21111
16001S 2000/S 2400/C
80 80 80 80
TIME
DATE
Ol :05
27/11
26/11
27/11
"MALTS IS 1I00/S 15001S 2000/S %200/S lIOO/C 0200/S
VALUE 0 . 16 0 . 17 0.11 0.17
0.17 0.11
O'lO/C
0.11
ANALYSIS
VALUE
0410/C
2200 / 5
13820 11500 9000 13320 8700 12000 13100 'EI'HT ( lG) 13820. 25500
HOO/C
ANALfSlS
ilUliHT (lli)
lUtO ZSSOD
VALUE
o ,9Z10
WEIGHT (KC)
lJI20
25500 ZZZZO
25500 W£IGHT
(KG )
7U4Q
Bin Report. CONCLUSIONS
Distributed on-line handling systems, providing both Droduction and distribution departments a direct and easy access to vital production information, are very powerful management tools for the . optimization of the overall manufacturlng operations . It has been demonstrated that Plant Mananement Information Systems, developed arou~d a mini-computer network, are both effective and economically justifiable for the daily operations. Indicative to this fact is the ever expanding scope of such applications within our company.