Auxiliary heating

The need for auxiliary heating is another factor that must be carefully evaluated. Due to the nature of the thermodynamic process, the gas discharging from an expander is at a much lower temperature than gas discharging from a regulator station operating within the same pressure bounds. If temperatures downstream of the expander are allowed to drop too low, potential problems may arise, such as hydrate formation and material compatibility. 

There are several methods available to avoid problems with low discharge temperature. One solution is auxiliary heating. The gas can be heated upstream of the expander this is called pre-heating. The gas can also be heated downstream of the expander, known as post-heating. 

Lubricating-oil governor and seal system cleaned Instrumentation and speed control checked Auxiliary heat recovery system Centrifugal Compressors... 

A catalytic afterburner, in which the surface action of catalysts allows incineration to take place at a temperature lower than a direct flame, reducing the auxiliary heat required, or... 

Hot lay-up is most suited for standby and for short outages for minor repairs. Here, the metal surfaces are maintained at 170 °F (77 °C) or higher by an auxiliary heat source, such as a gas air heater, to deter moisture. Typically, magnesium-based treatments are employed at the rate of 1 lb per 1,000 lb/hr of steaming capacity to absorb and neutralize sulfuric acid vapor. These products are blown through the fireside using the FD fan. 

Apart from use in metallurgical research and measurements, solid electrolytes have also been put to use as heating elements in electrical resistance furnaces. In order to prevent electrolysis from occurring, alternating currents must be used. In contrast to metallic heating elements, they may be used in air at around 2000 °C. In view of the fact that their conductivity must be very low at room temperature, there is a need for them either to be kept continuously warm, or to be preheated with an auxiliary heating element. 

Last but not least of the liquid calorimetric media are aqueous solutions used in the hydrolysis of simple and complex fluorides. Stepwise replacement of F by OH occurs, and mixed products are not unusual. Thus the BFj ion hydrolyzes to species BF (OH)l and one has to ensure that the same product composition is formed in the auxiliary heat experiments (99). The problem is accentuated when polynuclear species form, as the equilibration can be slow. The inconsistencies in the heats of alkaline hydrolysis of MoF6 and WFe found by various authors and of the enthalpy of SbF5—derived by assuming SbF5 and Sb205 dissolved in 10 M HF produced the same species in solution—illustrate the difficulties. It is as well to confirm enthalpies of higher valent fluorides obtained by hydrolysis by alternative nonaqueous methods, especially since uncertainty in the Afl (Fderived enthalpy. The advantage of hydrolysis methods, apart from the simplicity of technique, is that the heats are small and one can tolerate... 

This furnace will also provide auxiliary heat for domestic hot water when solar energy cannot provide this function. At times, while on winter mode operation, there will be days when cooling may be required. When this... 

At in auxiliary heat exchangers—i.e., those exchanging heat between feed solution and the two outgoing product streams 0... 

A second method of process intensification for recuperative reactors is to enhance performance by using a reactive coolant or heating medium, since the heat effects associated with reactions are usually much larger than those available with phase changes or simpler heating and cooling procedures. The coupling of an exothermic auxiliary heat source reaction with the desired endothermic reaction, or vice... 

Auxiliary heating equipment such as steam generators must be maintained to the local safety requirements. 

During the course of the subsequent steps, we may find that we lack suitable manipulators to achieve the desired economic control objectives. Then we must change the process design to obtain additional handles. For example, we may need to add bypass lines around heat exchangers and include auxiliary heat exchangers. 

One process modification is shown in Figure 8. In this modification, a heat recovery system uses the heat of the recovery column bottoms in the main column reboiler and in a bottoms preheater. If additional heat is needed in the main column reboiler, auxiliary heating is provided as shown by the (dotted) steam coil in Figure 8. However, a waste heat boiler is sometimes needed (shown dotted) to remove the excess heat in the recovery column bottoms. 

K) = -88.9 0.14 kcal mol using heat capacities of the materials. This value, when combined with auxiliary heats of formation (2,... 

Al20g 3 HgOCcr, gibbsite) 2 LiAlOgCcr) + 3 HgOU). Combining this a H with auxiliary heats of formation (2, 5) yields... 

We use auxiliary heat of formation data from JANAF (3 ) and estimate the... 

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