Control: heat, 201 microprocessor

There are many heat choices available and a wide choice of temperature controls as there is with other fabricating processes. They range from simple mechanical thermostats to solid state units with PID control, to microprocessors that are proportional, programmable, and self-tuning (Chapter 3). 

Rheological and processability behaviors were studied in a Monsanto processability tester (MPT), which is an automatic high-pressure capillary viscometer. The entire barrel and capillary are electrically heated with a microprocessor-based temperature controller [14], The... 

The calender was developed over a century ago to produce natural rubber products. With the developments of TPs, these multimillion dollar extremely heavy calender lines started using TPs and more recently process principally much more TP materials. The calender consists essentially of a system of large diameter heated precision rolls whose function is to convert high viscosity plastic melt into film, sheet, or coating substrates. The equipment can be arranged in a number of ways with different combinations available to provide different specific advantages to meet different product requirements. Automatic web-thickness profile process control is used via computer, microprocessor control. 

Chiron provides a microwell plate heater, a luminometer, and data management software. The plate heater is specially designed to provide precise control of the hybridization temperature (0 0.5°C) and to distribute heat evenly throughout the microwell plate. The luminometer maintains a temperature of 37°C and accommodates the 96-well plates. The data management software runs on an IBM PC or compatible computer with a minimum of 80386,16-Mhz microprocessor, 2 Mb of RAM, monitor, mouse, compatible printer, MS DOS (version 5.0 or greater), and Windows (version 3.1 or greater). 

Fig. 2.1 Schematic diagram of the CMR [22]. 1, reactants for processing 2, metering pump 3, pressure transducer 4, micro-wave cavity 5, reaction coil 6, temperature sensor 7, heat exchanger 8, pressure regulator 9, microprocessor controller ...

Fired heaters are extensively used in the oil and gas industry to process the raw materials into usable products in a variety of processes. Fuel gas is normally used to fire the units which heat process fluids. Control of the burner system is critical in order to avoid firebox explosions and uncontrolled heater fires due to malfunctions and deterioration of the heat transfer tubes. Microprocessor computers are used to manage and control the burner system. 

The carbon analyzer consists of three principal parts the combustion system, the laser reflectance system, and the microprocessor control. The combustion system is shown in Figures 1 and 2. Four filter disks, each 0.25 cm in area, are mounted vertically in a quartz boat which is located in the loading section of the combustion oven. The oven is purged with a 2% 02-98% He mixture, and the temperature of the heating zone is set to 350 C. 

It is important to recognize that a production reactor is not simply a reaction chamber. If it is a low pressure unit, there will be a vacuum system which can be quite complex. There will be a gas panel which regulates gas mass flow into the chamber. The method of heating the wafers and/or the entire chamber has to be chosen carefully. Wafer transport involves many tradeoffs, and for batch systems if any degree of automation is required, will be quite involved. Finally, most production reactors these days operate under microprocessor control, and quite a lot of software must be developed. 

A tube furnace drawn over the mullite outer casing is used to heat the contents to a specified temperature, based on a furnace control thermocouple. At the same time, a constant ac voltage2 is applied across the central heater. The microprocessor waits until temperature fluctuations (within 0.1°C, over one minute) at any of the inside or outside thermocouples are eliminated.3 At that point, steady state conditions are assumed to exist. 

Cook AP, MacLeod TM, Appleton JD, Fell AF. HPLC studies on the degradation profiles of glucose 5% solutions subjected to heat sterilization in a microprocessor-controlled autoclave. J CUn Pharm Therap 1989 14 189-195. 

Other features have been added to some designs, including heat storage systems (rock piles, masonry partition walls or floors, and heat storage tanks, ineluding water and gels), microprocessor control of vents and eirculation, and dehumidifiers. 

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