Temperatures, industrial graphs

The temperature of the surface of the Earth is rising about 0.10-0.15°C per decade (see graph). If current trends in population growth and energy use continue, by the middle of the twenty-first century the concentration of CO, in the atmosphere will be about twice its value prior to the Industrial Revolution. What are the likely consequences of this doubling of the CO, concentration ... 

Ammonia gas is made industrially by the Haber process, which involves the reaction between the gases nitrogen and hydrogen. The amount of ammonia gas produced from this reaction is affected by both the temperature and the pressure at which the process is run. The graph shows how the amount of ammonia produced from the reaction changes with both temperature and pressure. 

Calculations using Arrhenius plots, such as those described above, are carried out in the pharmaceutical industry every day. It should be made clear, however, that they involve a number of assumptions. It is assumed that the linearity of the graph obtained from equation (9.9) extends to room temperature, or, mathematically, that A and E are independent of temperature. If the line cannot be extrapolated to room temperature, shelf-life predictions are invalid. Second, it is assumed that the same chemical reaction is occurring with decomposition at high temperature as at low temperature. This is usually the case, but until proven it remains an assumption in most calculations. 

The more detailed use of the graphs and tables given in this chapter to establish suitable heat treatment times and temperatures is best illustrated by means of worked examples. Two such examples are given which are based on typical industrial problems that have been referred to TWI in the past. 

The phase behavior of mixtures forms the basis of industrial separations. What makes such separation possible is the fact that when a mixture is brought into a region of multiple coexisting phases, each phase has its own composition. Understanding the phase behavior of multicomponent systems is very important in the calculation of separation processes. In this chapter we review graphical representations of the phase behavior of binary and ternary systems. Since we are dealing with several independent variables, pressure, temperature, and composition, special conventions are used in order to represent information in two-dimensional graphs. 

Risk graphs are popular in the process industries for the assessment of the variety of trip functions - high and low pressure, temperature, level and flow, etc - which are found in the average process plant. In this appheation domain, the benefits listed above are relevant, and the criterion that there are a number of fimetions whose risks can be aggregated is usually satisfied. 

In practice, stability is satisfactory if the viable yeast population is less than 1 cell/ml. It might be preferable to set a lower limit (for example less than 1 cell per 100 ml) but in this case the sample would have to be filtered for the germ count. This operation can be very difficult, if not impossible—for example, with new sweet botry-tized wines. The number of pasteurization units required to sterilize a wine in terms of its constitution is given in Table 9.5. The heating time directly depends on the industrial pasteurization flow rate. From the graph in Figure 9.1, the required temperature can be predicted. 

Central Electronics Engineering Research Institute, Pilani has developed an accurate and reliable microprocessor-based industrial grade 24-channel temperature controller (Micro-TEIMAC) which has been successfully field-tried in a few sugar factories of U.P. and Maharashtra. A unique feature of the Micro-TEIMAC system is the twenty-four channel controller. It provides 4-20 mA PID controller current output and helps in controlling the temperature of all the twenty-four channels automatically either with the help of stepper motor driven low torque valves or pneumatically controlled high torque valves and manually with the help of control status and deviation indicators by providing visual indication to the valve operator. In addition to this controller displays actual deviation of process temperature from set point in the form of bar graph for all 24-process points and has the facility to connect recorder to all points. 

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