Computer processing control automation

A recent trend in particle analysis has been the introduction of personal computer-based automation (3). Sophisticated software packages can be used to automate and speed up the analysis. In some cases these computers can even carry out continuous process control (qv) (see Computer technology). The latest machines also allow the measurements of smaller particles and can detect a wider range of sizes. Machines based on light-scattering principles are being more widely accepted by the industry because of speed. An average analysis takes from 1—2 min, whereas those based on sedimentation principles require from 10—120 min. 

Bioprocess Control An industrial fermenter is a fairly sophisticated device with control of temperature, aeration rate, and perhaps pH, concentration of dissolved oxygen, or some nutrient concentration. There has been a strong trend to automated data collection and analysis. Analog control is stiU very common, but when a computer is available for on-line data collec tion, it makes sense to use it for control as well. More elaborate measurements are performed with research bioreactors, but each new electrode or assay adds more work, additional costs, and potential headaches. Most of the functional relationships in biotechnology are nonlinear, but this may not hinder control when bioprocess operate over a narrow range of conditions. Furthermore, process control is far advanced beyond the days when the main tools for designing control systems were intended for linear systems. 

Sec. 820.70 Production and process controls - Address production procedures and process controls, changes to the process, environmental controls, clothing and hygiene of personnel, prevention of contamination, suitability and layout of buildings, equipment qualification, maintenance, periodic inspection, and adjustment, removal of unwanted manufacturing materials from devices and automated (computer controlled) processes... 

Apparatus. Since all the polymer modification reactions presented in this paper involved gas consumption, an automated gas consumption measuring system was designed, fabricated and used to keep constant pressure and record continuously the consumption of gas in a batch type laboratory scale reactor. Process control, data acquisition, and analysis was carried out using a personal computer (IBM) and an interface device (Lab-master, Tecmar Inc.). 

Development of automated batch process control systems has lagged behind that of continuous process control. Flexible factory scale commercial systems have only begun to appear in the last five years (1-4). Increases in the performance/price ratio of small computers are now making automation of laboratory scale batch processes more practical. 

Automation and control of processing equipment by highly sophisticated computer control systems is becoming the standard at most hydrocarbon facilities. Automatic control provides for closer control of the process operating conditions and therefore increased efficiencies. Increased efficiencies allow higher production outputs. Automation is also thought to reduce operator manpower requirements. However other personnel are still needed to inspect and maintain the automatic controlling system. All process control systems should be monitored by operators and have the capability for backup control or override commands by human operators. 

One of the popular trends in laboratory automation is to arrange for a personal computer to control the gas chromatography and to receive data from the GC to be processed as desired. Bilateral communication is made via the RS-232C interface built in a GC 14A series gas chromatograph. A system can be built to meet requirements. 

An automated system, by definition, should perform a required act at a predetermined point in the process and should have a self-regulating action. This implies that intervention by the analyst is not required during the procedure and that only those systems that incorporate a microprocessor or computer to control and monitor their performance can be designated as automated. Some systems may not comply strictly with this definition but are a valuable means of mechanizing laboratory activities. 

Automation has been applied for a number of years in process control instrumentation, but the major impetus to introduce automatic devices into laboratories stems from three sources (1) the introduction of the continuous-flow principles as outlined by Skeggs [1] (2) the general demand for clinical chemical measurements, which represents a ready and sizeable market for instrument companies, and, more importantly, (3) the abihty to handle large volumes of data and package them in a form suitable for presentation to analysts and customers, through the use of mini- and micro computer systems hnked to a control computer. 

Clearly the major difference between the 1990s and earlier times is the availability of inexpensive and rehable computing and control facilities. Time is a fundamental part of laboratory automation and, in the area of computer data processing, the rapid changes that have taken place over the last 25 years are quite startling. Results from analytical measurements can now be almost instantaneous. There is a ready access to computer power, commercial interface cards and even bespoke software. 

New to the industry is the requirement that all electronically kept records be validated in accordance with the CFR (Title 21, Volume 1, part 11 revised April 1, 2003 requirement. This is particularly true of instances in which the systems are custom-designed and, furthermore, where computer-controlled automated processes are used. There remain many misconceptions about makes up computer validation. The CFR guideline as listed below should be well understood ... 

It should be clearly recognized that the subject of computing is not synonymous with automation, as seems frequently to be suggested. The usefulness of computing, separated from direct process control, is an established fact. The relationship of computers to automation in the process industries is still so embryonic that it does not seem advisable to dwell on it in a review of this type. 

The automation concept implemented at Conroe is called computer production control (CPC).2 CPC systems are driven by a general purpose process-control computer (48-K core memory) centrally located and programmed to monitor production and equipment operations and perform oil and gas accounting. As shown in Fig. 11, the computer is connected to a supervisory control system with a computer interface unit (CIU) to provide remote data acquisition and control function capability. 

The concentration of all automation functions within a single computer (Section 7.19.1) may be possible for a very simple plant, but this type of configuration is inefficient for more complex processes for which there could be many thousands of connections between plant and computer. Currently, small industrial processes are controlled by a hierarchical architecture consisting of a central computer (usually a minicomputer), which is used to solve central automation problems, together with a series of peripheral computers (generally microprocessors which are called front-end computers) which control different sections of the plant (Fig. 7.104a). This type of architecture is termed a decentralised computer system. 

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