Process control, automatic complex systems

In addition to the instrumentation in the safety circuitry, additional instrumentation systems are provided for operational control of the reactor complex. These additional instruments are designed to permit reactor operators to manually maintain control of the system or, in the event of approach to process limits, to shut the reactor down independently of the automatic safety circuitry. The safety circuitry will over-ride manual controls. 

The last twenty years of the last millennium are characterized by complex automatization of industrial plants. Complex automatization of industrial plants means a switch to factories, automatons, robots and self adaptive optimization systems. The mentioned processes can be intensified by introducing mathematical methods into all physical and chemical processes. By being acquainted with the mathematical model of a process it is possible to control it, maintain it at an optimal level, provide maximal yield of the product, and obtain the product at a minimal cost. Statistical methods in mathematical modeling of a process should not be opposed to traditional theoretical methods of complete theoretical studies of a phenomenon. The higher the theoretical level of knowledge the more efficient is the application of statistical methods like design of experiment (DOE). 

A small weather station is illustrated in Figure 3.181. Such stations are usually available in both the cabled and the wireless forms to provide all the information that is needed to control and optimize the various alternative energy processes. These units are usually preprogrammed to provide simple meteorological data, and to perform the complex calculation of ETo (evapo-transpiration). The microprocessor-based systems automatically measure the variables and store the data before transmitting it to a user-supplied remote PC over distances of up to about 10 mi. The units are usually provided with a rechargeable battery pack and a spread spectrum radio transceiver. 

The homogeneity problem is specific to solid samples, as liquid and gaseous samples are considered homogeneous by nature. Thus, for solid samples, an automatic sampling process is recommended to obtain reliable analytical information. To select the most adequate system to obtain a homogeneous sample it is necessary to take into account the sample complexity and the stability of the sample within a certain period of time.37 Further, it is necessary to establish first the nature of analysis that will be used in sample control, especially when the limits of detection are low. One must also be wary of the many contamination risks from reagent impurities, laboratory vessels, laboratory climate, and the operator. 

The ARSA system is designed to operate continuously in remote areas with minimal maintenance and consumables limited to replacement bottles of nitrogen carrier gas and CO2 removal traps. Dryers and gas traps were chosen that could be automatically regenerated in the field. The system has many components and a complex path for the analyte gas that traverses the system. The numerous valves ( 100) for controlling the gas flow and trap regeneration processes require a control system about one order of magnitude more complex than that for the RASA system described in the preceding section, if the number of parts is taken as a measure of... 

When a system is more complex and there are more potential sources of dynamic variations, a more complicated control is required. Particularly in automatic systems where human operators are replaced by machines and computers, a thorough design of control responsibilities and procedures is necessary. Control activities include automatic control of individual machines, material handling, equipment, manufacturing processes, and production systems, as well as control of operations, inventory, quality, labor performance, and cost. Careful design of correct and adequate controls that continually identify and trace variations and disturbances, evaluate alternative responses, and result in timely and appropriate actions is therefore vital to the successful operation of a system. 

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