8.3
Batch Control Description, Terminology, and Standard S88 B. A. JENSEN (1995, 2004)
FEATURE SUMMARY Batch processing and automation are discussed in this section both from a management point of view and from the perspective of the types of software structures required to implement it. Other sections in this chapter also deal with the subject of batch control. Section 8.4 concentrates on batch processes and their automation, while Sections 8.8 to 8.10 are devoted to the automation of chemical batch reactors. In 1988, the Instrumentation, Systems and Automation Society (ISA) formed a standards committee to provide guidelines for the design and specifications of batch control systems as used in the process industries. Building upon previous work of the German NAMUR (Normenarbeits-gemeinschaft fur Mess und Regeltechnik in der Chemischen Industrie) and the Purdue Workshop TC-4 committee, the first part of the multipart standard (“Models and Terminology”) defined terminology specific to batch control systems to facilitate understand1 ing between manufacturers and users. It also defined a standard batch control architecture that outlined a hierarchical structure relating control equipment and data communications needed for the physical areas involved in batch control and a functional model that showed the relationships between the control activities of recipe management, production scheduling, information management, batch management, unit supervision, and process control (sequential and regulatory control) required in batch control. This evolved into an international 2 standard: IEC 61512-1. As such, the other sections are also turning onto IEC standards including “Part 2: Data Structures 3 and Guidelines for Languages,” IEC 61512-2 standard in 4 2003. “Part 3: General and Site Recipe Models and Repre5 sentation” was approved by ISA in March 2003, while 6 “Part 4: Production Records,” is expected shortly. In addition, a nonprofit, professional organization called the World Batch Forum (WBF) was established in 1994 to promote the exchange of information related to the management, operation, and automation of batch process manufacturing. This association of end users, vendors, consultants, and academics hosts an annual conference with formal presentations and technical papers dedicated to advance batch processing knowledge and technology, with a strict, noncommercial agenda. Other forums include the European Batch 1528 © 2006 by Béla Lipták
Forum (EBF) and Japanese Batch Forum (JBF), which facilitate the same agenda. Batch automation and batch control is unique depending upon the perspective used to describe it. Unlike continuous processes, a batch process has a finite beginning, middle, and end. Though it has been argued that continuous processes can be thought of as batch processes with very long batch cycle times, the uniqueness of batch control has to do with what procedure is performed, what formulations are used, and on what type of equipment. Batch processes are event-driven processes that vary with time. Charging, heating, reacting, agitating, cooling, and discharging are examples of sequential events in time requiring corresponding control actions. In the design of a batch control system, time-based process conditions and transition phenomena must be handled. Attention to abnormal events and the interface to the operator may actually take more of the design process than that of the actual automation. Batch processing can be viewed through three perspectives. One is from a process point of view. The second is an equipment view by which products are processed. The third is a product-based view, or recipe-based view. To that end, the discussion will first begin on the process point of view. BATCH PROCESS CLASSIFICATION A batch processing model must consider that a batch can have more than one end product and that production is possible in various plants or plant areas. Thus, batch processes can be classified according to either the number of products made or the physical structure of the process. Recipe Point of View A recipe is a batch entity that contains “the necessary set of information that uniquely defines the production require1 ments for a specific product.” That includes the header (purpose, source and recipe version product identification, creator, and issue date) the procedure (the strategy and set of instructions and action needed to carry out the production of a batch), formula (process input values, process parameter variables, and process output data), equipment requirements,
8.3 Batch Control Description, Terminology, and Standard S88
and miscellaneous information, such as material safety data sheets (MSDS) and any other material that may be related to the batch. Batch processes can be classified according to the number of chemicals, substances, or items produced, as follows: single procedure/single formula, single procedure/multiple formula, or multiple procedure/multiple formula. A single-procedure/ single-formula batch process produces the same product in each batch. The same operations are performed in the same sequence, using the same percentages of the raw materials, though the batch sizes may change. Many of these types of plants can be converted to continuous processes. The singleprocedure/multiple-formula batch process produces different grades of products that are similar but differ in formula quantities. The same operations are performed in each batch, but the quantity of raw materials or processing conditions are varied. The procedure is the same but the formulas are changed. Multiple-procedure/multiple-formula batch processes produce products by utilizing different methods of production or control. The procedures performed, the amounts of raw materials used, the processing conditions encountered, and the equipment used may vary with each batch. This is the most difficult of the three batch-type processes to automate.
Table 8.3a lists a variety of factors that can be considered in distinguishing batch processes.
TABLE 8.3a Variations in Batch Processes and Their Features Features
Single procedure/single formula Single procedure/multiple formula Multiple procedure/multiple formula
Topology of plant
Numbers of stages Series/parallel/networked Interconnections: fixed or flexible connections Shared or exclusive use resources allocations
Type of equipment
Single-purpose Multipurpose
Movement of batches
Fixed paths/varying paths from batch to batch predefined in a recipe Dynamic unit assignments coupled with continuous processes Automatic reblending/rework
Control activity levels
Safety interlocking Basic control Unit supervision Batch management Production planning and scheduling Information management Recipe management
Sequence requirements
Number of control actions, inputs, and outputs are small Number of independent sequences and parallel actions are small
Amount of operator intervention
As part of the normal execution includes verification of required manual actions Overriding the recipe in case of abnormal events with return to automatic execution
Exception handling procedures
Permissives for advancing through unit procedure Interlocks continuously checked, system suspends or is held on detection of abnormality Interlocks independent of operations and phases; same interlocks throughout batch; no jumping to other phases Interlocks cause jump to a safe state; interlocks are control-step independent Interlocks are a function of operations and phases; both shutdowns and jumps involved; may be a number of abnormal transitions and states
Requirements for batch data collection
Receiving and storing information on individual batches Producing output information on one or more batches Producing batch reports Maintaining a batch history archive
Product Point of View The product is the overall objective of any batch process. This view takes into account repeatability and quality of the batches produced. It is information intensive. It is concerned with batch and unit recipe cycle times, cycle time frequency, batch and unit recipe performance ratings, product quality, and other performance-based metrics. Questions are answered, such as, When was batch B-4290 made? What equipment was used? What products were in progress at 14:00, 2 May 2004? How was the product made in 2002? How long does it usually take to make this product? Which reactor typically makes this product the quickest? What other batches were in progress when B4290 was running? What products have the greatest variability in their production? A fully developed automation system with a historical recipe-based manufacturing execution system is required to support this view.
© 2006 by Béla Lipták
Choices
Types of recipes
Equipment Point of View Batch facilities can also be characterized according to the physical structure of the process facility. Three basic types of batch structures are series (single-stream) structures, parallel (multistream) structures, and networked structures. A series structure is a group of batch equipment through which a batch passes sequentially. It could be a single batch unit, such as a reactor, or several processing units in sequence. In the parallel structure several batches can be undergoing the same (or different) operations at one time. A hybrid of the two structures is a series/parallel batch process, also known as a networkedtype structure whereby the batch can pass through any equipment type. This requires the highest degree of sophistication in control equipment to achieve effective batch control.
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BATCH AUTOMATION Automation of batch production is composed of three functional levels: 1. Batch planning: The sequence of production is planned and scheduled taking into account the available resources, including raw materials, personnel, and equipment. 2. Batch control: Production flows and production steps are described. Recipes are processed and executed in this level. 3. Real-time monitoring and control: Basic equipment control is performed at this level. This classical process automation includes safety interlocking input/output processing, and routine sequential, regulatory, and discrete control. The control activities of an entire batch control system are shown in a hierarchical manner from the sensors and elements to the business planning level in Table 8.3b. In many organizations the lines between the levels may be quite blurred. Additionally, the levels may be compressing though the functions and activities are certainly valid. Batch planning activities involve process/product management, production/batch management and production planning and scheduling, batch control activities involve batch management and unit supervision, and basic equipment control activities involving sequential/regulatory/discrete control of physical control devices, such as sensors and actuators, and safety inter-
locking. The following paragraphs describe the control activities as they pertain to batch processes, from the lowest level on up. Batch automation is planned from top down and imple7 mented from the bottom up. Process/Product Management Process/product management is the highest level of control activity. This is where corporate planning for the business is made and is linked to the various operating units. Activities like material and resource planning (MRP), inventory planning, and accounting take place. Process/product management is an activity that accepts inputs, such as customer orders, and based upon a manufacturing strategy develops a production plan. The production plan can cover such topics as: What is to be produced? How much is to be produced? When is it needed? Where is it to be produced? How is it to be packaged? The output of the production plan becomes an input to the production schedule of the individual plant. Process/product management entails a broad range of corporate planning and provides the basis for management’s relationship with its operating units. Production Management Production management is made up of three control activities: recipe management, production scheduling, and batch history management.
TABLE 8.3b Control Activity Model Level Planning
Batch control
Monitoring and control
Function Process/product management
Production planning, inventory planning, general recipe management, etc.
Production management
Recipe management, production scheduling, batch history management, etc.
Batch management
Recipe generation/selection, batch execution supervision, unit activities coordination, log and report generation, etc.
Unit supervision
Unit allocation management, unit coordination, etc.
Process control
Sequential/regulatory/discrete control: device, loop, and equipment module control, predictive control, modelbased control, process interlocking, etc.
Safety interlocking
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Activity
—
Recipe Management A recipe is the complete set of data and operations that define the control requirements of a particular type or grade of product. A recipe is composed of the following types of information: (1) header, (2) equipment requirements, (3) formula, and (4) procedure. Headers provide information about the source and version of the recipes, such as recipe and product identification, author, issue, and date and any other pertinent batch information such as MSDS or hazard or toxicity issues specific to the product or processing activities and the like. Equipment requirements specify the type and size of equipment needed, such as glass lining required and 20,000-liter vessel required. Formulas are sets of parameters, such as types and quantities of ingredients, durations, and process condition set points, that distinguish the products defined by procedures. Procedures define and order the actions to be performed and the associated control requirements necessary for making a class of products in the batch process. The procedure defines the generic strategy for producing a batch product. A procedure is made up of unit procedures.
8.3 Batch Control Description, Terminology, and Standard S88
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Drawings General recipe
Includes
Procedure
Consists of an ordered set of Unit procedure
Consists of an ordered set of
Product-specific processing information
May be transformed into Site recipe
Includes
Site-specific information
May be transformed into
Operation Master recipe
Includes
Process cell-specific information
Consists of an ordered set of Phase
Is the basis for Control recipe
FIG. 8.3c Procedure model.
Includes
Batch ID, batch size, in-process, operatorand/or systemgenerated information
FIG. 8.3d Recipe model.
Unit procedures are an ordered set of operations that causes a continuous production sequence to occur in a unit. An operation is an ordered set of phases that defines a major processing sequence. And operations are made up of phases that accomplish a process-oriented task. Phases may include the control steps or control instructions that execute the base1 level control. The relationship is diagrammed in Figure 8.3c. The actual executable logic of the control is linked via the recipe information to a particular unit where the unit recipes, operations, or phases are run in the order determined by the recipe. In the current generation of control systems, the recipe management function maintains a set of master recipes for various products and families of products. Specific information of the batch equipment and units that can run each operation within the procedure are contained within the control recipe. A master recipe is constructed from the site recipe using the formulas, procedures, and equipment-specific information. The master recipe is selected and accessed by the batch management activity, which converts it to a control recipe. This control recipe is the batch-specific recipe that is ready to run. 1 The hierarchy of recipes is shown in Figure 8.3d. Utilizing process and product knowledge, a process analysis is performed and basic phases are determined. These basic phases, along with product knowledge from the laboratory chemist, are used to construct the general (corporatewide) recipe. Plant knowledge (for example, raw material availability) from the plant site engineer is used to transform
© 2006 by Béla Lipták
the general recipe to a site-specific recipe. Equipment knowledge (for example, what vessels and piping are available at the plant) is used to transform this site recipe into a master recipe. This master recipe is used as the basis for a control recipe when a batch is ready to be produced. The activities involved during recipe management are summarized in Figure 8.3e. Production Scheduling Schedules serve as guides for production requirements in terms of availability of equipment, personnel, raw materials, facilities, equipment, and process capacity. The schedule generally has many of the following objectives: 1. Minimize the processing time 2. Minimize the deviation from a master production plan 3. Optimize the production of products within quality guidelines 4. Minimize energy costs 5. Minimize the usage of raw materials 6. Minimize rerun Production scheduling accepts inputs such as the production plan and based upon a scheduling activity develops a production schedule that typically specifies batches/amounts to be produced, target trains/lines to be used, time targets,
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Process & product knowledge
Process analysis
Basic phases Store and manage basic phases
Product knowledge (chemist)
Construct general recipe Store and manage general recipes
Plant knowledge (raw materials etc)
General recipe System & equipment knowledge
Construct site recipe Store and manage site recipes
Equipment knowledge (train configuration) Create a production schedule
Master recipe
Construct phase logic
Phase logic
Site recipe
Store & manage phase logic
Construct master recipe Master recipe
Store & manage master recipes
Create control recipe
FIG. 8.3e Recipe activities.
product dispositions, and resource constraints. In essence, the master production schedule answers what to schedule, when to schedule, and how much to schedule. The production schedule further reduces the production plan, which was developed in the company management layer (process/production management) and directly drives the production of individual batches. The responsibility of the production scheduler is to develop a detailed time-based plan of activities to achieve the production targets set by the production plan. It needs to dynamically allocate a new schedule at any time. It should be feasible to reallocate or create a sched-
ule automatically via some algorithm or manually via user intervention. Schedulers can be implemented via any number of ways. Linear programs, expert systems, or other multivariable tech8 niques have been used successfully. The scheduler needs to provide a procedure or method for batch sizing and is the logical place where lot or even batch ID assignments are made. A production scheduling model is shown in Figure 8.3f. As shown by the model, a dynamic scheduler accepts user inputs, master recipe information, and updates from
To schedule generation Detailed schedule
User inputs
Dynamic schedule
Master recipe scheduling information
From batch mgmt.
FIG. 8.3f Production scheduling model.
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Batch schedule
8.3 Batch Control Description, Terminology, and Standard S88
process management to develop a batch or production schedule. The dynamic scheduler must be able to: Organize a new schedule at any time Provide for interactive scheduling Allow for manual intervention Determine the availability of resources Provide for a method to carry out the schedule Provide a procedure or method for the lot sizing along with a means to organize autonomous orders with this lot size Determine the feasibility of the schedule Information about times and availability of resources are key inputs to the scheduler. Because the basic data about the unit operations, master recipes, key times, resources, quantities, priority, and orders and their operations are required, it seems reasonable to conclude that the dynamic scheduler is a real-time activity. The dynamic scheduler requires non-real-time data from production planning and recipe management as well as real-time feedback data from the batch manager and lower-level control activities. The dynamic scheduler can contain some kind of optimizing capability. Batch management provides the updates of information to the scheduler in real time and also provides the status of material and equipment. The user needs to be advised of the schedule situation continuously. Thus, reporting and status information are important. Information provided to the user can include the control recipe, the lot number, the product being produced, the amount being produced, the train/line being used, the status of the recipe, the mode of operation, priority, start times, and end times. The mode of the lot in the queue determines whether the recipe is to start automatically, semiautomatically, or manually. In the manual mode, stepping through the batch sequence is done by the plant operator via specific commands. In semiautomatic mode, the batch sequence is initiated by the operator and requires operator intervention when proceeding from one phase or operation to another. In the automatic mode, once the sequence is initiated, it can be repeated a predetermined number of times without any operator intervention. The mode of the batches in the queue also determines whether any information in the queue is operator alterable, and whether the control recipe has been bumped or interrupted by another control recipe of higher priority. Batch History Management Batch history management is the subject of Part 4 of the ISA S88 standard. It has the following main functions: 1. Receiving and storing information from other parts of the overall batch control system on the individual batches 2. Producing output information from single batches, from several batches, or as an overview of multiple batches
© 2006 by Béla Lipták
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3. Producing batch reports on the basis of output information 4. Maintaining production records and batch history archive by supporting data reduction, backup, and deletion features Although many data logging and reporting techniques for batch processes are similar to those for continuous systems, production records have some significant requirements that may be different. Two needs are batch tracking (some may use the term lot tracking) and the batch end report. A batch historian must collect and maintain integrated, identifiable sets of dissimilar data. Batch tracking is the collection of this data. It is generally event-triggered and typically contains the following related data: Continuous process data (flows, temperatures, and pressures) Event data (operator actions, alarms, notes) Quality data (lab analysis, inspection notes) Recipe formula data (quantities desired and used, set points, times) Calculated data (totalizations, material usage, accounting data) Manual entries with audit trail (location of change, operator of record) Stage, batch, lot identification Time/date stamps on all data A batch end report may typically include a copy of the master and/or control recipe that was used to make the batch. This may not be identical to the original recipe because of operator modifications, equipment problems, and so on. Events such as alarms, operator instructions, and equipment status changes should also be logged. This log can be designed so that it will retain the total operational sequence chronologically with date and time. A trend chart can also be retained. A recipe expresses the desired approach by which a batch is to be made, while the batch report provides a record of how the batch was actually made. Batch management takes care of the recording and collecting of batch end reports, which are then archived to some other medium. Batch reports are a statutory requirement in some applications (for example, in the pharmaceutical industry); however, because the information is so valuable, it is being demanded in many other batch applications. A simplified batch history management model is shown in Figure 8.3g. Batch history management is an activity that is not bound to the actual execution time of the batches and not bound to the equipment on which the batches are produced. It involves the process of sorting out the production records and batch end reports, because even a perfect batch may be undeliverable without batch records. Advances in relational databases allow the bridging of data between the process control of current batches and the histories of previous batches. The ability to use standard query language (SQL)-like calls to
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Information Request Input
Site information Production planning and scheduling
Recipe management
Schedule update Production status
Manage site information
Batch history Equipment capability Manage batch information
Recipe scheduling info
User information & Batch collection requirements history
Batch information (history, reports, status)
Process management
Batch reports
FIG. 8.3g Batch history management.
access batch history allows new avenues to analyze and report batch histories. Other analysis techniques, such as statistical process control and statistical quality control (SPC and SQC), can be applied at this level. Batch Management Batch management interfaces with the user, recipe management, production scheduling, unit management, sequential control, and regulatory and discrete control in performing its functions of (1) recipe selection, transformation, and editing to manage batches; (2) initiation and supervision of batch processes; (3) management of batch resources; and (4) acquisition and management of batch information. A batch man1 agement model is shown in Figure 8.3h. Batch management includes basic functions to managing batches by using control recipe information, batch information, and equipment information to: 1. Select a master recipe from recipe management and transform it to a control recipe that can be used to run a batch 2. Assign a batch identification code 3. Time-stamp the control recipe when the batch identification is entered 4. Verify the information in a control recipe, such as its completeness and its ability to execute on the selected units 5. Maintain the control recipe until the batch is completed
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Additionally, the batch management function: 1. Initiates control recipe execution based on time or event 2. Assigns and releases units, and updates their status 3. Distributes the parts of the control recipe to unit supervision 4. Starts the batch based upon start conditions and the detailed schedule, whether upon event or time 5. Regulates the distribution of operation or phases for execution 6. Reports and time-stamps events for information management 7. Allows users to alter normal processing 8. Maintains batch status information 9. Allows batch to be suspended, removed, and later recalled Managing batch resources takes the detail schedule and master/control recipe information and provides for: 1. Dynamically predicting start and end times for batches and operations and tagging batch events 2. Maintaining the dynamic schedule of all batches, including their current state 3. Dynamically detecting resource requirements and resource availability 4. Updating production scheduling with modifications to the schedule
8.3 Batch Control Description, Terminology, and Standard S88
Master recipe
Batch progress and process cell status information
Batch scheduling information
Batch and resource information
Manage batches
Production information management
Production planning and scheduling
Recipe management
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Batch and process cell information
Manage process cell resources Process cell information
Collect batch and process cell information
Batch information
Unit recipes, commands, and batch and status information
Commands and status information
Unit supervision
FIG. 8.3h Batch management model.
Additionally, managing batch resources involves: 1. Receiving the detailed schedule 2. Dynamically detecting conflicts between resources needed and those that are available 3. Granting “permission” to unit to establish resource link 4. Arbitrating multiple requests for resources 5. Tracking and maintaining all batches, ready to run, inprogress, completed, or aborted Finally, batch management provides functions to acquire and manage batch information, such as: 1. Collecting and reporting batch information by batch, operation, phase, time, or event 2. Providing in-progress or complete batch reports 3. Archiving and retrieving batch data in batch history A batch report can include recipe data, snapshot process data, or batch data in response to the recipe or on an ad hoc basis necessary for documenting the batch. This includes operator modifications, historical trends, reports, and other information that may be available to the operator.
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Unit Supervision A unit consists of a physical grouping of equipment as well as the unit control functions required to carry out the execution of a batch. A process unit consists of a group of mechanical equipment; each piece performs, in a somewhat independent manner, a portion of the chemical process. Examples of process units are filters, batch reactors, heat exchangers, and distillation columns. Process control involves the actions required to perform the unit operations. Examples are charging, heating, cooling, agitating, reacting, discharging, and washing. Unit supervision interfaces with the user, batch management, sequential control, regulatory control, and discrete control in performing its functions of (1) communication with other units, equipment modules, and control modules; (2) acquisition of resources; (3) unit procedure execution; and (4) exception handling. The unit supervision model as currently defined by the ISA standards committee is shown in Figure 8.3i. Unit supervision requires certain information from batch management. The most important information is the recipe information required to run the unit. This recipe information contains the executable logic as well as formula information.
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Process management Manage process cell resources
Manage batches
Production information management
Batch and resource information
Acquire and execute procedural elements
Batch and unit information
Commands and status information
Unit recipes, commands, and status information
Unit information
Manage unit resources
Collect batch and unit information
Batch information
Unit supervision Commands and status information
Commands and status information Process control
Execute phases
Execute non-procedural control
FIG. 8.3i Unit supervision model.
Unit supervision performs the unit procedures, operations, and phases in the order they are to be run; performs exception logic when some abnormal condition arises during execution; and downloads parameters from the formulas to the control modules. When more than one processing unit affects the status or use of a resource, the resource is designated as a common resource. Common resources almost always exist with parallel and series/parallel batch process structures. A common resource may either be required exclusively or can be shared. Unit supervision coordinates with other units to account for exclusive-use and shared-use resources. Exclusive-use resources can be used by only one unit at a time. This means that some mechanism must be in place to prevent more than one batch from trying to use the resource at the same time. Also, the batch scheduling system must take this exclusive resource into consideration. Another problem is associated with distribution of risk in control systems. If a controller module containing the exclusive-use resource fails with no backup, all units utilizing the resource are affected. Shared-use resources are associated with units that can simultaneously use the common resource. A unit should not be able to deactivate the resource while other units are using it, and the capacity of the resource should not be exceeded by multiple users. The engineering of the equipment into units greatly affects how shared and exclusive resources are handled, which translates into the overall modularity of the batch control. As a batch processes through one unit to the next,
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the use of the equipment providing the transfers must be coordinated.
Process Control Sequential, regulatory, and discrete control functions interface directly with elements and actuators to cause changes in the process. Discrete control is concerned with maintaining the process states at a target value chosen from a set of known stable states. Regulatory control serves to maintain the measurements of a process as close as possible to their respective set point values during all events, including set point changes and disturbances. Sequential control sequences the process through a series of distinct states as a function of time. These types of control functions are implemented using control modules and equipment modules. A control module device is an item of process equipment that is operated as a single entity and that may have multiple states or values. Discrete states are initiated (using hardware and software) to control discrete devices such as solenoid valves, pumps, and agitators. A control module loop is a combination of elements and control functions that is so arranged that the signals pass between elements for the purpose of measurement or control of the process variable. A proportional, integral, derivative (PID) control algorithm is a common control loop function. An example of equipment module control is the sequential control of dehydrator bed control valves in order to put one bed on-line while the other bed is being regenerated according
8.3 Batch Control Description, Terminology, and Standard S88
to a time schedule. Most of today’s process control systems utilize function blocks as the tools to describe and implement control modules. Process interlocking and advanced control, in the forms of feedforward, predictive, or model-based control, are additional control functions that reside at this level and serve to achieve a higher level of automation to obtain additional benefits. As opposed to continuous processing, additional control algorithms and control methodology are normally used in batch processing. Functions such as time-based PID (heat soak ramps), charging algorithms, sequencers, and timers are often required. Techniques such as enabling/disabling control functions based upon a phase state, enabling/disabling alarms on devices and loops, and employing antireset windup protection on PI or PID loops are commonly used. Batch processes tend to be device-oriented, while continuous processes are predominantly loop-oriented. Safety Interlocking Safety interlocks ensure the safety of operating personnel, protect the plant equipment, and protect the environment. These types of interlocks are initiated by equipment malfunction and usually cause shutdown. Often, a separate system is used in implementing the safety interlocks. This system includes the necessary redundancy and fault tolerance, and is independent from the other control functions. An example of a safety interlock is the stopping of a centrifugal compressor if its gear oil pump has failed, thus preventing mechanical damage. Safety interlocking serves a different purpose from process interlocking or permissive interlocking. Process interlocking can be safety-related, but it is primarily associated with the process. An example of a process interlock is to stop charging a material if the agitator is not running. A permissive interlock establishes an orderly progression of sequences. An example would be to not allow the feeding of an extruder before the barrel temperature has reached a minimum value.
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1. Charge times: Ingredients must be metered accurately and be added to the mixers or reactors as fast as possible. Dribble charging and other anticipatory methods are used to accurately charge the correct amount of an ingredient. 2. Reaction times: Good temperature control and accurate pressure detection are essential in order to produce consistent reactions batch after batch. Liquid chromatographs measuring molecular weight distributions and many other analyzers have been used to determine the end of the batch reaction. 3. Dump time: Reactor contents are emptied. Level devices or NMR devices have been used here to determine when the batch has been dumped completely. 4. Turnaround time: After a batch is dumped, the time until the next batch can be charged should be minimized. Benefits of automation acquired through reduced utility costs can be achieved by minimizing heating medium usage and minimizing cooling medium usage. Benefits of automation acquired through higher product quality are much more difficult to define. They would normally translate to higher customer satisfaction and less reject material. These benefits can be achieved by achieving tighter control of the batch reactors and higher accuracy and consistency in charging the raw materials. Once the architecture of the plant is known, the control strategies can be planned. An example of a batch plant is shown in Figure 8.3j. In his paper presented at the World Batch Forum techni9 cal proceedings in 1998, Christie provided his nine points for batch automation design: 1. 2. 3. 4.
Understand the process before generating the design. Don’t implement until you have designed. Get the user involved in the design. Document the design.
Raw materials
ENGINEERING The effort to automate a batch facility is done to achieve operational benefits. Generally, benefits can be achieved through (1) increased production, (2) reduced utility costs, and (3) higher product quality. Many manufacturers use reduction of off-spec materials due to operator error, which affects all three of the above criteria, as justification for automation. For batch reactors, benefits acquired through increased production through automation can be achieved via reduced batch cycle times, minimized turnaround time between batches, and better scheduling of reactors for like products. Decreased cycle times for each reactor are certainly measurable and are easy to quantify. A reactor cycle can be thought of as having four separate steps:
© 2006 by Béla Lipták
Reactor A
Ingredient 1 Ingredient 2
Reactor B
Phases Charge Heat Cool Discharge
Centrifuge feed tank
Tank
Ingredient 3 Recycle
Centrifuges A-F two trains
FIG. 8.3j Batch process example.
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Control and Optimization of Unit Operations
5. 6. 7. 8.
Agree on the recipes. I/O assignments are important. Don’t underestimate the state transition matrix. Pay particular attention to exception handling, the hard part of batch. 9. Batch reports are not an add-on. Inherent in the message is that the design based upon S88 concepts allows easier implementation and a high degree of modularity, translating into easier modifications and lower maintenance costs. Today’s process automation suppliers have embraced the S88 standard concepts into their system architectures, facilitating more modular design and implementation. With that, Fleming and Schreiber in their 1998 World 10 Batch Forum paper on batch processing design counsels the designer to consider process segmentation so as to: Identify the process cell first Identify the units after the boundary of the process cell has been identified Identify the equipment modules in the process cell and units Identify control modules in all other modules Verify equipment module boundaries against defined procedural elements Verify unit boundaries against defined procedural elements Finally, verify the process cell boundary against defined procedural elements The key to design is to segment the process properly so that the controls can be equally identified and segmented. Poor segmentation results in a batch control system that is difficult
Preparation Select reactor A prod A Tank ready ?
Premix
to support and enhance. A batch control system that fails to exploit the inherent flexibility of the plant and recipe development that requires the assistance of control system developers will result in an implementation that cannot be flexible, resulting in inflexibility of the organization to respond to 11 product needs. Sequential control functions can be diagrammed to express the logic of batch control. Such diagrams include paradigms such as ladder diagrams (change-oriented), matrix diagrams (state-oriented), flow diagrams (flow-oriented), petri-nets (data/flow-oriented), Gantt charts (state-oriented), and sequential function charts (GRAPHCETS). Many of 12,13 these tools are listed as possible recipe formats. Most all process automation systems claim to be S88 based. In that regard, most, then, utilize function blocks for control modules and sequential function charts for procedures, unit procedures, or operations as their engineering tools to implement batch control automation. Figure 8.3k is an example of a batch procedure for the batch process shown in Figure 8.3j. It shows the time sequence of activities in making a specific product. Between the activesequence phases, idling, holding, and waiting states can occur. These states can allow information exchanges with other batch process units or can receive directives from operators. Failsafe, emergency, or exception handling states can also be defined along with these phases. Formula information from the recipe is loaded into controllers at the proper time when executing the phases. Formula information is a list of parameters, such as temperature set points, flow set points, quantities or totalization set points for ingredients, transition times, controller modes, and whatever else is needed by the phases. Finally, at the end of the design and implementation aspects of automation design comes testing of the batch control
Reacting
Charging
Set tank ready
Refill tank Charge reactor A Reactor ready ?
Heat reactor A
Set reactor ready
Cool reactor A Dump reactor A
End report
FIG. 8.3k Batch procedure time sequence.
© 2006 by Béla Lipták
8.3 Batch Control Description, Terminology, and Standard S88 14
and automation. Pillai’s phase testing guidelines state to clearly define the modules, clearly define the testing strategy, clearly define the test plan, perform the tests, document the test results, and initiate change control.
When the plant configuration is known, the steps necessary to engineer the control of the process can be defined. Figure 8.3l shows the engineering steps performed by the control engineer. However, many other kinds of disciplines
Start
Define the process cell
Define the unit typicals
Reference the P&IDs
Define the individual units
Define measurements and control devices
Reference the P&IDs
Define continuous and discrete functions (equipment and control modules)
Using standard control system engineering tools e.g., function blocks ladder logic or other representations of equipment and control module functions
Define recipes
Determine unit procedures determine formula dataprocess inputs, parameters, and process outputs
Define unit procedures
Define phase logic
Define phase logic
FIG. 8.3l Batch process control flowchart.
© 2006 by Béla Lipták
Define SFC, time-sequence diagrams ladder logic structured text, or other language depictions for each entity and its interface from the recipe entity to its associated equipment entity
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Define common use resources
Determine shared/exclusive use resources
Define modes/states/ commands and their transitions
Define actions upon auto, semi-auto and man. Similarly define actions for states like hold, pause, run, suspend, etc.
Define overall abnormal conditioning handling
Determine alarming strategy and actions associated with error conditions, such as putting the unit or batch to a specific state like suspend
Define the interface and messages to required to selecting and running the recipe for the operator
Design graphic, trend groups, messages, and other interfaces the operator requires to execute control recipes and follow the batch as it runs
Define general performance and management reports
End
Batch logs Batch historization Batch reports
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Recipe management Process analysis
Procedure, process stages, process operations, & process actions
Control and Optimization of Unit Operations
Process & product knowledge
Construct general recipes
Store & manage General general recipes recipe
Product knowledge (chemist)
Create/transform to recipe procedure Plant knowledge (raw materials, etc.)
Create/transform to site recipes
Create/transform to unit procedure Create/transform to operations
Store & manage site recipes
Equipment knowledge (train configuration) Product knowledge (formula)
Site recipe
Create/transform to phases
Create/transform to master recipes
Unit supervision
Batch management Store & manage master recipes Production scheduling and planning
Business objectives
Customer orders
Create the production plan
Master recipe
Resource data Production plan
Create the production schedule
Create control recipe
Control recipe
Initiate & supervise recipe execution
Unit recipes
Recipe information Manage batch resources
Production schedule
Information management Data & information to various applications & users
Store and manage batch history
Batch history
Acquire, store & manage batch data
Batch reports
FIG. 8.3m Consolidated control activities.
© 2006 by Béla Lipták
User information
Execute equipment recipe functions
Process control regulatory/descrete/sequential control Execute control functions
Sensors and actuators
8.3 Batch Control Description, Terminology, and Standard S88
are involved in the entire process. Figure 8.3m illustrates the engineering activities required at various levels by people with different backgrounds and qualifications. Process and product knowledge from central engineering provides the input to construct basic phases for the procedure of making a product. This knowledge combined with product knowledge of the research or development chemist is used to construct general recipes. Plant knowledge provides the information to convert the general recipe to a site-specific recipe. Plant engineers also have the equipment knowledge necessary to construct phase and operation logic and to transform the site recipe into a master recipe by knowing the specific trains/lines on which the product can be made. Process control engineers then are able to use both system knowledge and process knowledge to create the control recipe, which is system-specific and is designed to execute a batch. The control engineers also use their knowledge to design, configure, and implement the lowerlevel control functions required to provide process control. Management information systems (MIS) people implement process/product management and turn business objectives and customer orders into a production plan that is used to create a production schedule. Batch history archives may be maintained by MIS or plant computer system personnel. Therefore, overall batch control implementation requires the talents of many disciplines.
understandable by all who participate in it, regardless of the industry or the products involved. The goal is a modular, maintainable, flexible batch automation implementation.
References 1.
2. 3.
4. 5.
6.
7. 8.
9.
10.
CONCLUSIONS Execution of a batch process is a sequence of processing stages, operations, or actions. These stages, operations, or actions are independent process-oriented events within the overall batch operation, such as charging, heating, reacting, agitating, cooling, and discharging. These stages, operations, and actions translate to unit procedures, operations, and phases, which are defined by boundaries that define safe or logical points where one can charge an ingredient or direct a finished product to a different downstream vessel. The set of sequences under which these are performed constitutes the batch operation. The user must be considered at each level of the control activity. The operator interface allows the operator to interrupt automated commands received from higher activity levels and to enter information or to command the process directly. Data can enter the system at any level. Also, an output can be generated at any level where it is needed and then be transmitted to the next higher or lower levels. The models defined by the ISA batch control standards committee are designed to be valid for batch processing facilities, regardless of the level of automation involved. The control activity levels are designed to be collapsible in case those functions are not applicable. From plants whose recipes are on paper and whose control is done by manual valves to fully automated paperless batch manufacturing facilities, the descriptions and terminology of the batch process should be
© 2006 by Béla Lipták
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11.
12. 13.
14.
ISA S88.00.01, “Batch Control, Part 1: Models and Terminology,” Research Triangle Park, NC: Instrument Society of America (ISA), 1995. IEC 61512-1, “Batch Control, Part 1: Models and Terminology,” International Electrotechnical Commission (IEC), 1997–08. ANSI/ISA-88.00.02, “Batch Control Part 2: Data Structures and Guidelines for Languages,” Research Triangle Park, NC: Instrument Society of America, 2001. IEC 61512-2-2002, “Batch Control, Part 1: Models and Terminology,” International Electrotechnical Commission, 2002. ANSI/ISA-88.00.03, “Batch Control Part 3: General and Site Recipe Models and Representation,” Research Triangle Park, NC: Instrumentation, Systems, and Automation Society (ISA), 2003. ISA-88.00.04 Draft 3b, “Batch Control Part 4: Production Records,” Research Triangle Park, NC: Instrumentation, Systems, and Automation Society, 2003. Christie, D., “The Top-Down Approach to Successful Process Control Projects,” Control October 1989. Reklaitis, G. V., “Scheduling Approaches for the Batch Processing Industries,” Proceedings of the World Batch Forum, Newton Square, PA, May 1995. Christie, D., “A Methodology for Batch Control Implementation — Real World Lessons,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. Fleming, D. W., and Schreiber, P. E., “Batch Processing Design Example,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. Hancock, J., and Hopkinson, P., “A Case History of the Implementation of an S88-Aware Batch Control System,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. ISA-TR88.0.03, “Possible Recipe Procedure Presentation Formats,” Research Triangle Park, NC: Instrument Society of America, 1996. Emerson, D., “What Does a Procedure Look Like? The ISA S88.02 Recipe Representation Format,” Proceedings of the World Batch Forum, San Diego, CA., April 1999. Pillai, V., “S88 Phase Testing and Change Management,” Control, March 1999.
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Control and Optimization of Unit Operations
Feldmeyer, E., Alsup, M., and Burns, H., “Recipe Interface Requirements for Flexible Batch Control Systems,” Proceedings of the Industrial Computing Conference, Vol. 1, Instrument Society of America, Anaheim, CA, October 1991. Ghosh, A., “An Approach to a Flexible and Easy to Use Batch Control System,” Proceedings of the Industrial Computing Conference, Vol. 1, Instrument Society of America, Anaheim, CA, October 1991. Hornbeck, D., “A New Approach to Batch Process Control,” Proceedings of the Industrial Computing Conference, Vol. 1, Instrument Society of America, Anaheim, CA, October 1991. Larson, K., “Flexibility Takes Center Stage in Batch Process Automation,” Control, November 1991, pp. 24–33. Massey, L. E., “The Development of Modular Batch Automation Techniques,” Proceedings of the Industrial Computing Conference, Vol. 1, Instrument Society of America, Anaheim, CA, October 1991. Nowicki, P. L., “Transforming Recipes is the Key to Flexible Batch Processing,” Proceedings of the ISA/91, Vol. 46, Part 2, Instrument Society of America, Anaheim, CA, October 1991. Alsup, M., “Recipe Configuration for Flexible Batch Systems,” ISA/93 Technical Conference, Chicago, September 19–24, 1993. Tom, T. H., “DCS Selection for Flexible Batch Automation,” ISA/93 Technical Conference, Chicago, September 19–24, 1993. Bullotta, R., “Designing Effective User Interfaces for Batch Processes,” Proceedings of the World Batch Forum, Phoenix, AZ, March 1994. Offenbacher, F. M., and Smith, E., “Integrated Production Scheduling,” Proceedings of the World Batch Forum, Phoenix, AZ, March 1994. Van de Pol, P., “Real-time Production Scheduling in a Multipurpose BatchOriented Environment,” Proceedings of the World Batch Forum, Phoenix, AZ, March 1994. Webb, M., “Computer System Implementation, Batch Standards, and Validation,” Proceedings of the World Batch Forum, Newton Square, PA, May 1995. Rosenof, H., “Dynamic Scheduling for a Brewery,” Proceedings of the World Batch Forum, Newton Square, PA, May 1995. Chappell, D. A., “Recipe Requirements for Dissimilar Manufacturing Trains: The Ultimate Complexity,” Proceedings of the World Batch Forum, Newton Square, PA, May 1995. Deitz, D., and Snyder, B., “Automating a Modern Bio-Manufacturing Plant: A Case Study,” Proceedings of the World Batch Forum, Toronto, ON, May 1996. Gudaz, J., “Batch in the Context of Field-Based Control,” Proceedings of the World Batch Forum, Toronto, ON, May 1996. Nomikos, P., “Detection and Diagnosis of Abnormal Batch Operations,” Proceedings of the World Batch Forum, Toronto, ON, May 1996. Korkmaz, B., and Parapar, R., “Equipment Flexibility in a Pilot Plant Operation,” Proceedings of the World Batch Forum, Toronto, ON, May 1996. Clark, P., Grove, P., Liu, B., and Joglekar, G., “Using Simulation to Verify the Decision Logic of Batch Control Systems,” Proceedings of the World Batch Forum, Toronto, ON, May 1996. Uhlig, R. J., “Batch Control in a Resin Plant,” in ISA Practical Guide Series for Batch Control, Research Triangle Park, NC: ISA, 1996. Nisenfeldh, A. E., and Leegwater, H. (Eds.), Batch Control, Research Triangle Park, NC: ISA, 1996. Berber, R., “Control of Batch Reactors: A Review,” Trans. IChemE., 74(A), 3–20, 1996. Sano, Y., Watanabe, H., and Yoshida, M., “Design Approach to Developing the Batch Control System,” Proceedings of the World Batch Forum, Houston, TX, April 1997. Tom, T. H., “Handling Product Related Exceptions Using the S88 Concept of Modular Batch Automation,” Proceedings of the World Batch Forum, Houston, TX, April 1997. Choi, J. Y., Mercure, P. K., and Rhinehart, R. R., “Optimization of a Batch Polymerization Reactor,” Proceedings of the World Batch Forum, Houston, TX, April 1997.
© 2006 by Béla Lipták
Lawrence, F. B., and Robinson, E. P., “Optimization Procedures for Scheduling Batch Packaging Operations,” Proceedings of the World Batch Forum, Houston, TX, April 1997. Koning-Bastiaan, H., “Process Model and Recipe Structure, the Conceptual Design for a Flexible Batch Plant,” Proceedings of the World Batch Forum, Houston, TX, April 1997. Owen, J. M., “Evangelizing S88.01: Converting the Masses,” Proceedings of the World Batch Forum, Houston, TX, April 1997. Wooley, K., and Christie, D., “Achieving Increased Batch Plant Productivity by Application of a Multi-Level DCS Solution,” Proceedings of the ISA, Houston, TX, October 1998. Kawano, K., “Applications of Batch Progress Prediction by Rolling Scheduling to Operation Support System,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. Emerson, D., and Himono, R., “Automated Scheduling in a Polymer Plant,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. Akesson, K., and Tittus, M., “Modular Control for Avoiding Deadlock in Batch Processes,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. Poulsen, L., “Paperless Batch Production — A Practical Example from the Pharmaceutical Industry,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. Musier, R., Sundaram, S., and Vardy, J., “The Recipe Model: New Advances in Using Life-Cycle Principle in the Batch Industry R&D and Manufacturing Environment,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. Korkmaz, B., and Pillai, V., “Unit Supervision — A Key Component in Process Management and Process Control,” Proceedings of the World Batch Forum, Baltimore, MD, April 1998. LeBlanc, L., and Malenfant, M., “How S88 Provides Consistency in Design and Terminology beyond Batch Processing,” Proceedings of ISA, 1998. Jensen, B., and Lagonikos, P., “Automation Philosophy of a Pilot Plant for Active Pharmaceutical Intermediates/Ingredients,” Proceedings of the World Batch Forum, San Diego, CA, April 1999. Brooks, T., “Batch-Based Historians,” Proceedings of the World Batch Forum, San Diego, CA, April 1999. Korkmaz, B., Pillai, V., and Srinivasan, R., “Guidelines for Exception Handling Design for Batch Processes,” Proceedings of the World Batch Forum, San Diego, CA, April 1999. Zarichniak, S., “The Inherent Reusability of Batch Phases and Devices,” Proceedings of the World Batch Forum, San Diego, CA, April 1999. Crowl, T., and Wolin, D., “The Paperless Batch Plant,” Proceedings of the World Batch Forum, San Diego, CA, April 1999. Kandadamy, S., and Ibrahim, E., “Automation of a Lube Oil Additives and Blending Plant Using an S88.01-Consistent Batch Software — a Case Study,” Proceedings of the World Batch Forum, San Diego, CA, April 1999. Kerrick, S., Smith, S., and Charpientier, L., “A Most Unusual Approach to Implementing S88 Recipes,” Proceedings of the World Batch Forum, San Diego, CA, April 1999. Nishitani, H., and Niwa, T., “Modeling & Simulation of Pipeless Batch Plants,” Proceedings of the World Batch Forum, San Diego, CA, April 1999. Ito, H., and Emerson, D., “Integrated MMI for Batch Process Operations,” ISA TECH, 1999. Chen, L. W., Salisbury, R., and Kamal, S. Z., “Scheduling in Batch Process Plant Perspective,” IMS, 1999. Adler, D., “Trends in Manufacturing,” Interkama Technical Conference, Dusseldorf, Germany, 1999. Liefeldt, A., Lohl, T., Stobbe, M., and Engell, S., “Simulation and Scheduling of Recipe-Driven Batch Processes Based on a Single Data Model,” Interkama Technical Conference, Dusseldorf, Germany, 1999. Koning-Bastiaan, H., Schreil, C., and Roy, C., “Automated Execution of Bio Tech Batch Manufacturing,” Interkama Technical Conference, Dusseldorf, Germany, 1999.
8.3 Batch Control Description, Terminology, and Standard S88
Parshall, J. H., and Lamb, L. B., “Applying S88: Batch Control from a User’s Perspective,” Research Triangle Park, NC: ISA 1999. Brandl, D., “Using Corporate Recipes to Accelerate Time to Market,” Aspenworld 2000 Technical Session, Orlando, FL, February 2000. Brandl, D., “Batch Automation Is Coming of Age,” Chemical Processing, September 2000. Huzmezan, M., Gough, B., Kovac, S., and Le, L., “Advanced Control of Batch Reactor Temperature,” Proceedings of the ISA Expo, 2000. Drillenburg, C., “Tracking and Tracing on an ISA S88 Foundation,” Proceedings of the ISA Expo, 2000. Benton, A., “Batch Control Application Frameworks and Reuse,” Proceedings of the World Batch Forum, Atlantic City, NJ, April 2000. Fisher, T. G., “Batch Control: Applying the S88.01/IEC 61512-1 Standards,” Proceedings of the World Batch Forum, Atlantic City, NJ, April 2000. Brandl, D., Emerson, D., and Ward, B., “Batch Schedules and Production Schedules: Which Should You Use?” Proceedings of the World Batch Forum, Atlantic City, NJ, April 2000. Roy, C., and Wyshak, G., “Implementing Automated Batch Control of a Biotechnology Manufacturing Facility Using S88.01 Concepts: A Case Study,” Proceedings of the World Batch Forum, Atlantic City, NJ, April 2000. Himono, R., Mano, K., and Takahata, K., “An Integrated System with Batch Functions and Front-End Scheduling Based on S88: Application to Beverage Plant,” Proceedings of the World Batch Forum, Atlantic City, NJ, April 2000. Koning-Bastiaan, H., “Production Information Management,” Proceedings of the World Batch Forum, Atlantic City, NJ, April 2000. Stapper, H., and Verhagen, A. M., “Benefits of Advanced Engineering Methodologies for the Design and Support of Batch Projects in the Pharmaceutical Industry,” Proceedings of the World Batch Forum, Brussels, Belgium, October 2000. Rickard, J., “Combining Optimal Off-Line Scheduling with On-Line Supervisory Control,” Proceedings of the World Batch Forum, Brussels, Belgium, October 2000. Hauff, T., “Batch Manufacturing: Status and Future Challenges,” Proceedings of the World Batch Forum, Brussels, Belgium, October 2000. Ghosh, A., “Maximizing the Potential of Batch Process Control,” Proceedings of the World Batch Forum, Brussels, Belgium, October 2000. Morse, C., “S88 Case Study for Improved Production Flexibility, Safety, and Environment,” Proceedings of the World Batch Forum, Brussels, Belgium, October 2000. Craig, L., “S88 Process Modularization,” Proceedings of the World Batch Forum, Brussels, Belgium, October 2000. Vanhove, G., “Tracking and Tracing on an ISA S88 Foundation,” Proceedings of the World Batch Forum, Brussels, Belgium, October 2000. Amkreutz, R., and van Beurden, I., “Safety in Batch Production,” Proceedings of the ISA Expo, 2001. Jensen, B. A., “Six Sigma and S88 Unite for Batch Automation Productivity Improvement,” Proceedings of the World Batch Forum, Orlando, FL, April 2001. Christie, D. A., “Automatic Adaptation of Batch Logic to Changing Field Automation,” Proceedings of the World Batch Forum, Orlando, FL, April 2001. Wilson, P., “Batch Application Migration,” Proceedings of the World Batch Forum, Orlando, FL, April 2001. Branch, T., and Ray, T., “Batch Automation Project Increases Production,” Proceedings of the World Batch Forum, Orlando, FL, April 2001. Crowl, T. E., and Heckmanski, J., “Design Methods to Defer Costs on Batch Projects,” Proceedings of the World Batch Forum, Orlando, FL, April 2001. Kovacs, K., “Designing Batch Systems for e-Manufacturing,” Proceedings of the World Batch Forum, Orlando, FL, April 2001. Patnaik, S., “Master Batch Record Management,” Proceedings of the World Batch Forum, Orlando, FL, April 2001.
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Johnson, L., and Roy, C. “Use of Web Technologies in Batch Management,” Proceedings of the World Batch Forum, Orlando, FL, April 2001. Givens, M., and McDonald, A., “Repeated S88 Success Yields Cost Reductions at Large Consumer Products Company,” Proceedings of the World Batch Forum, Orlando, FL, April 2001. Christie, D., “Life’s a Batch,” InTech, July 2001. Blanchard, I., “Batch Control Systems Current and Future,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2002. Årzén, K.-E., and Olsson, R., “Exception Handling in S88 Using Grafchart,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2002. Marklew, C., “Electronic Batch Records and Flexible Batch Reporting,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2002. Staus, R., “Improved Temperature Control in Batch Production Systems,” Proceedings of the ISA, 2002. Holy, R., and Pozivil, J., “Batch Control System Project for a Pharmaceutical Plant,” ISA Transactions, 2002. Sanchez, A., Rotstein, G., Alsop, N., Bromberg, J. P., Gollain, C., Sorensen, S., Macchietto, S., and Jakeman, C., “Improving the Development of Event-Driven Control Systems in the Batch Processing Industry: A Case Study,” ISA Transactions, 2002. Lorenzo, D., and Pérez, N., “Applying Model Predictive Control to a Batch Process,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2003. Pettus, N., and Wolf, D., “Automated Batch Scheduling and MES Integration Using a Hierarchical Based, Batch Control Software Architecture,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2003. Arnold, J., and Brandl, D., “Automating the Manufacture of Highly Energetic Organics Using the S88 Model,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2003. Hunter, M., “Real-Time Batch Control and Materials Management in Perfume Production,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2003. Clark, S. C., “S88 Design and Implementation Case Study for a Complex Bulk Pharmaceutical Batch Process,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2003. Brill, E., and Yulevitch, O., “Targeting Batch Outcome Using Predictive Control,” Proceedings of the World Batch Forum, Woodbridge Lake, NJ, April 2003. Parks, J., and Yuki, T., “Using Alarm and Event Analysis to Achieve Batch Productivity Improvements,” Control Solutions, February 2003. Bonvin, D., and Srinivasan, B., “Optimal Operation of Batch Processes via the Tracking of Active Constraints: A Case Study,” ISA Transactions, Research Triangle Park, NC: 2003. Gough, B., Kovac, S., Devito, L., and Quick, D., “Model Predictive Control of Batch Temperature,” Proceedings of the World Batch Forum, Chicago, IL, May 2004. Fu, C., “Functions to be Considered in Batch Material Transfer Controls,” Proceedings of the World Batch Forum, Chicago, IL, May 2004. Brun, T. A., “Transfer Lines as Unit in an S88 Frame,” Proceedings of the World Batch Forum, Chicago, IL, May 2004. Marjanovic, O., Lennox, B., Lovett, D., and Sandoz, D., “Statistical Process Monitoring of Industrial Batch Processes,” Proceedings of the World Batch Forum, Mechelon, Belgium, October 2004. Martin, E., and Morris, J., “Monitoring Multi-recipe Batch Manufacturing performance,” Proceedings of the World Batch Forum, Mechelon, Belgium, October 2004. Mecchretto, S., “Integrated Batch Processing: A Recipe fpr Advanced Manufacturing in the Process Industries,” Proceedings of the World Batch Forum, Mechelon, Belgium, October 2004.
