Temperature recorders, cost

Degree-days Temperature data recorded over a 24-hour period as deviation from a certain base temperature used to deter mine the operating costs of a heating or air conditioning system depending on the external climatic conditions. 

Table 9E-9 lists unit operations in the polystyrene plant. The highest temperature is 400°F, in the extruder. From this and Figure 9-5, a temperature factor of 0.04 is obtained. There are no high pressures except in the extruder, and its value is unknown. The pressure factor will be assumed to be zero. Stainless steel is used, so the material factor is 0.2. From Equation 2 a complexity factor of 3.48 can be calculated. A direct process investment cost of 350,000 per functional unit is obtained from Figure 9-7. This means that the cost of constructing the plant when the Engineering News Record Construction Index (ENRCI) is 300 would be 3,150,000. This will be updated to 1960 when the ENRCI was 350, and then the CEPI will be used to obtain the cost in 1974. The resultant cost in 1974 is... 

Advantages of the RSST are its relatively low cost and its availability to permit a quick evaluation for potential runaways. Pressurized conditions may be used. The temperature-time curve and the concurrent pressure increase (of the containment vessel) can be recorded, which are measures of the reactivity hazards of the substance or reaction under investigation. The temperature-time curve shows the lowest temperature at which a runaway can be detected in the test system (initiation temperature, To). 

Research chemists found that they could modify the conducting properties of solids by doping them, a process commonly used to control the properties of semiconductors (see Section 3.13). In 1986, a record-high Ts of 35 K was observed, surprisingly not for a metal, but for a ceramic material (Section 14.24), a lanthanum-copper oxide doped with barium. Then early in 1987, a new record T, of 93 K was set with yttrium-barium-copper and a series of related oxides. In 1988, two more oxide series of bismuth-strontium-calcium-copper and thallium-barium-calcium-copper exhibited transition temperatures of 110 and 125 K, respectively. These temperatures can be reached by cooling the materials with liquid nitrogen, which costs only about 0.20 per liter. Suddenly, superconducting devices became economically viable. 

The simpler and most reliable approach to the use of the DIERS methodology is the use of FAUSKY s reactive system screening tool (RSST). It is an experimental autoclave which simulates actual situations that may arise in industrial systems. The RSST runs as a differential scanning calorimeter that may operate as a vent-sizing unit where data can readily be obtained and can be applied to full-scale process conditions. The unit is computerized and records plots of pressure vs. temperature, temperature vs. time, pressure vs. time, and the rates of temperature rise and pressure rise vs. the inverse of temperature. From these data it determines the potential for runaway reactions and measures the rates of temperature and pressure increases to allow reliable determinations of the energy and gas release rates. This information can be combined with simplified analytical tools to assess reactor vent size requirements. The cost of setting up a unit of this kind is close to 15,000. 

Ferrite ceramics have found widespread applications as materials for permanent magnets and recording media due to their low cost and attractive magnetic properties. The conventional method for manufacturing ferrite ceramics involves solid state reaction of oxide or carbonate precursors at high temperature. Although technically simple, this method does not readily allow control of the product s microstructure and purity, which is necessary for the attainment of optimal magnetic properties. As a result, there has been considerable research into the development of alternative synthesis techniques. 

A more versatile alternative to a flow monitor is a measurement of the absorbance of each of the collected fractions on a spectrophotometer. This can be done automatically at reasonable cost with digital or strip chart recording. The results, of course, are not available as the experiment is in progress and the fractions may be exposed to room temperature for the measurement but this system can be more... 

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