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Brewing automation & data management; effective coordination and operations linkage in the planning stage can expedite brewhouse automation.

Brewing Automation & Data Management

The complexity of brewing operations makes the automation process a challenging combination of intelligent communication and effective coordination. In the early stages of automation, process control systems tend to evolve from the automation of stand-alone unit operations (brew kettles, fermenters, etc.) and typically have been designed to perform their function without the interaction of other systems. Subsequent attempts to integrate these "islands of automation" sometimes result in problems because of incompatible systems. This results from the failure to consider the needs and requirements of a fully integrated system. Accordingly, there is great incentive in the planning stage to provide the most effective coordination and linkages between operations, whether you are considering a full automation project or "staged" automation. The topics discussed in this article include the selection of field instrumentation and control systems, communications and integrated date management. The outline provided should be useful for managers and others involved in the planning and design of brewing automation projects.

Instrumentation and Control System


The control and data handling requirements for a project define the control system functionality. This is sometimes termed the "conceptual scope". Control system selection should be based on the needs and requirements of each project with consideration given for future expansion and integration.

Batch process control, which is common in the brewing industry, is characterized by the simultaneous manipulation of both analog and discrete variables based on a given batch sequence. The batch program defines the order of procedures, phases and steps required to produce a given recipe, and manipulates the required discrete devices and regulatory controllers.

The regulatory or analog control measures flows, pressures, temperature and other process variables, and adjusts final control devices (i.e. a control valve) to correct the error detected between the desired set point and measured variable. Analog inputs can be either 4-20 milliamps DC, 1-5 VDC or 1-10 VDC and are proportional to the measured variable (i.e. 0-100 gal./min.= 4-20 mA). Analog outputs are either 4-20 mA DC, or 1-5 VDC signals which are sent out from the controller to adjust the position of a final control device.

Discrete control, also known as digital or on/off, manipulates the positions of solenoid valves and start/stop switches, sensing position by switch closures from limit switches on valves, flow switches, pressure switches, temperature switches and proximity switches. Digital outputs are typically 120 VAC, 12 VDC or 24 VDC.

Field Instrumentation & Intelligent


The importance of instrument engineering is often overlooked in today's focus on Computer Integrated Manufacturing (CIM) and multi-level definitions of automation. Even the most sophisticated and fully integrated process control system is limited by the integrity and robustness of the sensors and final control devices. A steam control valve on a brew kettle with the wrong valve characteristics will operate just as poorly whether it is connected to a pneumatic or microprocessor-based controller. Proper instrument engineering is essential in any automation project, and its importance should not be underestimated.

Communications is also a key element in the overall structure of control systems. The process controller receives digital and analog inputs from sensors and analyzers which monitor the process and perform preconfigured operations. The controller then sends output digital and analog signals to equipment and control devices which manipulate the process. The process controller also coordinates operations involving the interaction between analog and digital control and handles sequential and data management functions. In addition, the controller also provides real-time communication to weigh scales, bindicators, analyzers and programable logic controllers.

It is important to recognize that the control system is part of a larger computer system which collects data from laboratories, barcode readers, PCs and other devices. The control system can be linked through an ancillary computer or device to access data from these devices. System design must be such that their communications do not interfere with the process control system, while the information is shared as required. For example, a bar-code reader is used to track raw materials usage by lot number. The information is used by the control system for batch reporting and the MRP II system for materials management.

The rapid reduction in the cost of microprocessors has resulted in the introduction of intelligent transmitters and sensors. As a result, many of the functions previously handled by the process control computer are now handled by the instrument itself. As an example, consider the intelligent flowmeter. Instead of the normal 4-20 mA output, the intelligent transmitter generates and transmits flow range, engineering units, sealing factors and configuration parameters. It is also capable of converting the analog flow rate to digital signal. Thus, there is a definite need for communications between the process controller and the intelligent transmitter, called a field bus. Currently, there is no industry standard for field bus communications and many vendors use their own protocols. The Instrument Society of America's SP-50 Committee is attempting to develop a standard communications protocol to resolve this problem.

Single and Multi-loop Controllers/PLCs/PC-based


Microprocessor-based single and multi-loop controllers provide cost-effective and powerful tools for brewery automation. Many are used in the control of brew kettles and fermenters. These controllers can either be used in stand-alone applications or integrated with programmable logic controllers (PLCs), or into PC-based and/or large diistributed control systems. Today's state-of-the-art single and multi-loop controllers are also computational microcomputers with the ability to perform detailed batching and sequential operations in addition to traditional loop control, and allow the user to configure predefined control strategies (PID, CASCADE, RATIO, etc.) or to custom program the controller using function blocks.

An example of the microprocessor-based hardware used to implement automation of brewing applications is Fischer and Porter's Micro-DCI control system. A typical system (see Fig. 1) consists of a supervisor, single and/or multi-loop controllers, computational micro-computers (Chameleons) and a personal computer. The integrated PC-based system consists of IBM PC/AT (or compatible) Supervisor-PC which has an Intel 8031-based co-processor and operator's keyboard. The 8031 co-processor communicates with the controllers and PLC over an RS-422/485 multi-drop data link. The PC, which operates as a host computer, primarily functions as an operator interface, while the control functions remain in the controllers and PLC. The Supervisor performs data aquisition, history, recipe management and control by exception functions for some complex batch-sequencing functions. The PC also functions as an engineering workstation which can be used to configure the controllers, edit process graphics and program and troubleshoot the PLC. One Supervisor is capable of accessing the memory locations of up to 32 inter-connected controllers and micro-computers and two Supervisors can be installed in each PC. The PC-based operator control systems are efficient and cost-effective, and can be networked to a VAX computer using Decnet for plant-wide data management operations.

Distributed Control Systems

For large brewers, a completely distributed control system such as Fischer & Porter's DCI system provides cleaner architecture (Fig. 2). The DCI system allows greater flexibility integrating digital and analog control, and supports a wide range of applications software for data and plant management. The DCI system includes distributed control units (DCUs) which are powerful microprocessor-based multi-loop control modules. Each DCU is capable of controlling up to 64 analog loops and up to 1000 I/O points.

As many as 32 DCUs can be distributed throughout the brewery so that each DCU is located close to the process equipment it controls minimizing field wiring runs. The DCUs are connected using a data highway, which can be used to share information with another DCU or device. The DCUs are also capable of controlling process unit operations independent of the data highway. The DCUs interface with the process using standard industrial transmitters, thermocouples, RTDs, Micro-DCI controllers, PLCs, weigh scales and analyzers. Each of these devices is fully-integrated into the DCI system. which means real-time operation on data residing in the PLC will not be different from an operation on data coming into a DCU's own process I/O.

At the unit operations level, the operator interface is the Local Operators Center (LOC). Each LOC is connected to as many as four DCUs via a serial link. The LOC consists of a color CRT and operators keyboard, and provides powerful interactive graphics, report generation, logging and trending. At the process management level, the Distributed Operators Consoles are highway-based computer and operator interfaces that provide access to all I/O points connected to any DCU on the data highway. The Distributed Operators Console also provides a choice of mass storage devices, interactive control graphics, data collection, process calculations, advanced control strategies, report generation and a wide range of application software.

The data highway was developed to allow rapid sharing of data stored in another computer. As an example, the Fischer & Porter Data Highway links the DCi systems control, operator station, computation and communication devices into an integrated network capable of operating at the fastest commercial data rates available while assuring the high level of security required for plant-wide operations. The Data Highway is based on IEEE 802.3 and complies with the ISO seven-layer protocol for Open Systems Interconnect. A host (or main frame) computer which is part of the plant management network can be connected by a gateway on this data highway. A variety of general and brewing specific applications software is available on distributed control systems and their host computers, for recipe and brewhouse management, product scheduling, process performance, batch tracking and data archiving.

This includes a software package called Brewmat. Brewmat is a comprehensive brewhouse package developed jointly by Fischer & Porter, the Master Brewers Association of America and one of America's largest breweries. Brewmat's capabilities include: aquisition and storage of process and manually-entered data, brewhouse reporting and tracking, fermentation and brewhouse status and overview, recipe handling and editing, free format logs and process efficiency calculations and reports. Trend displays of process data vs. recipe values are also available, i.e. temperature and density profiles for fermenters and temperature profiles for mash mixers and brew kettles.

Another currently available program is the Brewhouse scheduler software. The Brewhouse package provides on-line calculations and plots of any real-time or historical variable on the network through Statistical Process Control (SPC). This includes standard-deviation, manual, processcapability, histogram, X-Bar/R, Cusum, X-Y scatter and Pareto charts. The Dynamic Optimization feature offers on-line analysis and correction of any process variables for consistent quality, energy reduction and overall process cost reduction. Other features of the Brewhouse software package include an Automatic Database Verification, designed to provide automatic documentation and notification when any unauthorized or unintentional modification is made to the configuration.

For brewers planning automation projects, proven technology is available. The challenge lies in the coordinated application of that technology, and the key lies in careful planning, whether for a full automation project or a gradual effort. The problems inherent in piecemeal automation can be overcome if brewers carefully consider the requirements of a fully-integrated system before proceeding.

PHOTO : John W. Via is an industry applications engineer at Fischer & Porter Co. He holds a B.S. degree in chemical engineering from Lamar University and is currently a Ph.D student at the University of Delaware. Mr. Via is director-elect of the Maintenance Division of ISA and is a member of ACS, AICHE, Alpha Chi Sigma, ISPE and NSPE.
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Author:Via, John
Publication:Modern Brewery Age
Date:Jan 22, 1990
Previous Article:Up to speed; computer technology keeps pace with industry changes.
Next Article:Automated beer blending; a brewery equipment manufacturer propounds the benefits of automated beer blending.

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