Other Heating Media

Dielectric heating is used to dry printing inks, adhesives, and coating materials on paper, as well as to dry the paper itself. This has been combined with hot air, infrared, and other heating media to achieve optimum results. Some examples of commercial installations include the following [9] ... 

Heat tracing In many processes, equipment, instruments, and piping systems require externally applied heat. This heat may be applied by electrical tracing leads attached to the item or line or through a small bore pipe or tubing that carries steam or other heating media (e.g., hot oil). An example of a steam-traced line is shown in Exhibit 1-10. 

The column bottom level is sometimes controlled by bottoms draw. Varying reboiler heating medium is another possibility. For some cases, bottoms draw level control works better and for others, heating medium level control. BojnowskF gives a case where heating medium level control was desired for two columns in a plant. One... 

Shell side Usual procedure for condensing steam or for other heating, medium. 

Steam-tube Rotary Dryers. Material is passed through a long rotating cylinder A shell around the cylinder enmams steam, hot water, or other heating medium. 

This temperature may cause film boiling of 6I°P propane in the reboilers, in which case the steam can be used indirectly to heat water, an oil, or other heating medium for use in the reboiler. 

Distillation tends to be a very large consumer of heat in any chemical factory and may be the deciding factor in determining at what pressure steam must be generated or to what temperature hot oil or other heating medium must be raised and distributed. 

Heater or Cooler. This is the unit operation where a process fluid exchanges heat with a utUity stream. For example, the heater is the one where the process fluid receives the heat from steam or other heating medium, and the cooler is the one where process fluid gives out the heat to cooling water or other cooling medium. 

For a fixed liquid level in the column base, the volumetric percent vapor in the tubes increases as steam (or other heating medium) flow rate is increased. As shown by Figure 4.2, this effect is very pronounced at low heat loads but tapers off" at higher loads. The end result is similar to boiler swell (Chapter 10, reference 6) an abrupt increase in steam flow causes liquid to be displaced back into the column base, with a resulting temporary increase in column base level. 

Base levd is most commonly controlled by manipulating one of three variables (1) bottom-product wididrawal, (2) steam or other heating medium flow,... 

Consider Figure 19.2 where top-product flow is set by flow control, reflux flow is set by condensate receiver level control, boilup is fixed by flow control of steam or other heating medium, and bottom-product flow is determined by column-base level control. As shown by the dotted line, we wish eventually to control column top composition by manipulating distillate flow. Let us assume that feed rate, feed composition, feed enthalpy, and boilup are fixed and that we wish to find the changes (i.e., gains ) of top and bottom compositions in response to a change in D, the top-product rate. 

Steam (or some other heating medium) can be condensed within a coil or jacket to heat liquid in a stirred tank, and the inlet steam pressure can be varied by adjusting a control valve. The condensation pressure Pg then fixes the steam temperature Tg through an appropriate thermodynamic relation or from tabular information such as the steam tables (Sandler, 2006) ... 

The utilization of gas turbine exhaust gases, for steam generation or the heating of other heat transfer mediums, or in the use of eooling or heating... 

Boilers are heat-transfer devices, wherein water, in the form of either liquid water or gaseous steam, is commonly employed as a medium for the transport of heat to some distant point of use. Although other heat-transfer mediums are sometimes utilized, water is particularly suitable because of its relative abundance, low cost, and high heat capacity. It is generally the medium of choice in most boiler applications, whether for domestic, commercial, institutional, or industrial purposes. 

The butyl alcohol is pumped from storage to a steam-heated preheater and then to a vaporiser heated by the reaction products. The vapour leaving the vaporiser is heated to its reaction temperature by flue gases which have previously been used as reactor heating medium. The superheated butyl alcohol is fed to the reaction system at 400°C to 500°C where 90 per cent is converted on a zinc oxide-brass catalyst to methyl ethyl ketone, hydrogen and other reaction products. The reaction products may be treated in one of the following ways ... 

When GPPS is made, all but 238 pounds of styrene are heated to 200°F. For the other products less is heated up per batch, because less is used. The time to charge the reactor shall be set at 5 minutes. Steam at 150 psig will be used as the heating medium. 

The effect of thermal pion fluctuations on the specific heat and the neutrino emissivity of neutron stars was discussed in [27, 28] together with other in-medium effects, see also reviews [29, 30], Neutron pair breaking and formation (PBF) neutrino process on the neutral current was studied in [31, 32] for the hadron matter. Also ref. [32] added the proton PBF process in the hadron matter and correlation processes, and ref. [33] included quark PBF processes in quark matter. PBF processes were studied by two different methods with the help of Bogolubov transformation for the fermion wave function [31, 33] and within Schwinger-Kadanoff-Baym-Keldysh formalism for nonequilibrium normal and anomalous fermion Green functions [32, 28, 29],... 

A number of special vacuum distillation processes have been developed, whereby thermal decomposition of the oil is kept to a minimum. One of these employs thin film vaporization, in which mercury vapor is employed as an indirect heating medium (89, 71). Another employs a carrier other than steam—for example, kerosene—in the vaporization of the heavy lubricating oil fractions (16). These processes are being operated on a commercial scale, but apparently because of their special nature they have not been widely adopted by the petroleum industry. 

Table VI summarizes the effect of heating medium on the loss of acids after 3 minutes of microwave heating. Loss of volatile acids varied widely dependent on the microwave medium. Acetic and caproic acids had losses ranging from 20-80% and 0-73%, respectively, depending on medium composition. The dielectric property, specific heat, or other physical/chemical properties of individual flavor compounds can provide valuable insight into the potential behavior of these compounds during the microwave process. The dielectric property of the total food system and the affinity of the flavor compound for the microwave medium, however, were primarily responsible for the behavior of these flavor compounds during microwave heating.

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