Proportional temperature controller

Figure 16 illustrates a process system using a proportional temperature controller for providing hot water. 

The performance of the single-ended analog proportional temperature controller in the tracking mode is shown in Fig. 6.4. The measurement was done at room temperature, and the control voltage of microhotplate 1 was increased in steps of 100 mV. For example, a control voltage of 1.60 V produced a microhotplate temperature of approximately 355 °C. Microhotplate 2 was kept at a constant temperature of 200 °C and microhotplate 3 was kept at 350 °C. 

Fig. 6.5. Performance of the single-ended analog proportional temperature controller in the stabilization mode...

The heat exchanger consists of a small centrifugal fan that takes air from outside the unit and forces it, via ducts, into the four corners of the sample chamber. A heater made from Nichrome wire wound around a ceramic former is situated within the ducting immediately upstream of the fan. The temperature within the sample chamber is monitored by a thermistor set in the floor of the chamber and a proportional temperature controller maintains the temperature at 60°C. 

The experimental apparatus is shown in Figure 1. It consists of a 140 ml extraction vessel with an electrical heater provided with a proportional temperature controller (Coel, GMP) with... 

Within the enclosure, the 316 stainless steel reactor is sealed in a vacuum tight glass vessel at the bottom of which is a 5.08 cm window through which the incident and resultant laser beams pass. Up to 4 samples can be run at any time. The temperature in the reactor is controlled to 0.3°K at 800 K using a current proportional temperature controller [Honeywell UDC 5000]. The glass vessel containing the reactor is evacuated by a roughing pump initially, followed by a diffusion pump. 

The constmction of a gas manifold incorporating four mass flow controllers allowed the mixing of water saturated air with dry air to produce test streams of gas with accurate RH. Measured amounts of hydrogen were then added to the test stream. An environmental test chamber was also constructed from an insulated cooler. A heating element on the test chamber and a proportional temperature controller allowed control of the gas temperature and thus the thin film temperature to within 0. PC. 

The temperature in one of the tanks (T, Tj,or T ) is controlled by a proportional temperature controller that manipulates the heat input (2i to the first tank. The disturbance is a drop in inlet feed temperature To from 90°F to 70°F at time 0 hours. Three different values of controller gain Kc = 2, 4, and 8) are used. 

Calculate the ultimate gain and ultimate frequency of a proportional temperature controller. 

All reactions were carried out in 700-mL stainless steel, high pressure reaction vessels. The reaction solution was added, along with a Teflon-coated stirring bar, to a vessel that was flushed and loaded with CO to the desired pressure. The vessel was heated in an insulated oven, which rests on a magnetic stirring motor. Temperature control ( 1°C after the desired reaction temperature was reached) was maintained using a proportional temperature controller with a thermocouple inserted in a thermowell,. which extended below the solution level of the reaction vessel as a sensor. Heating the reaction vessel from room temperature to 160°C typically required from 40 to 45 minutes. 

The steel column was insulated in an electrically heated aluminum jacket and temperature-controlled using a solid-state proportional temperature controller. The latter device contained two potentiometers that could each be preset to provide particular temperatures. Temperature changes were controlled by the programmer. Published precision of the instrument is 5%. Typically, precision of commercial amino acid analyzers lies in the... 

The power consumption of the barrel and die heaters can be determined by measuring voltage and current to the heater. This works well in current proportioned temperature control. It does not work well with on-off control or time-proportioning temperature control. In the latter case, a wattmeter should be used with a power integrating function. In this case, the integrated power over a certain time period can be measured so that the average power consumption of the barrel heater can be established. Commercial extruders generally do not have sufficient instrumentation... 

The extruder drive should be able to hold the screw speed constant to about 0.1% or better the same holds true for the take-up device. However, this is not always the case on actual extrusion lines. The extruder should be equipped with some type of proportioning temperature control, preferably a PID-type control or better. On-off temperature control is inappropriate for most extrusion operations. 

The densities of pure components and their nrixtures were measured with an Anton Paar DMA 55 densimeter, and the refractive indices with an Abbe refractometer Type 3T., with accuracies of 0.01 kg my3, and 0.0002, respectively. Each apparatus was matched to a Julabo circrrlator with proportional temperature control aird an autonratic drift correction system that kept the samples at desired temperature usually 298.15 K with accuracy of 0.01 K. The densimeter was calibrated periodically with distilled water and dry air. 

Extrusion dies usually are made from alloy steel, finished to a few microinches, plated, and buffed. Hard chrome plating is used for most materials except corrosive resins such as vinyls where nickel is used. Temperature control to within 2-3 deg F is required at specific zones in the die. Proportioning temperature controllers with sensing elements deep in the die body provide excellent temperature control in electrical heating systems. In some applications, portions of the die may be cooled rather than heated for internal sizing and support of the extrudate. 

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