Gas flow heating

Von Sacken and Dahn [89], using TG-MS, showed that below 523 K the thermal decomposition of AMV proceeds by simultaneous release of ammonia and water in a constant proportion, regardless of whether the atmosphere is inert or oxidizing. Above 523 K, residual ammonia reduces the solid products so that the stoichiometry of the final residue is dependent upon the sample size, gas flow, heating rate and reactor design. 

Reynolds, T.J. (1978) Fluid Inclusion Adapted USGS Gas Flow Heating/Freezing Instruction Manual. Fluid Incorporated, Denver, CO. 

The difference between experimental data on the cylinder-gas flow heat exchange (Sc = 0.72) and the results obtained by the first formula in (4.4.25a) is less than 3% for Re < 0.2 [186]. 

Many stodies had demonstrated that pyroelectric anemometers based on single-crystal LiTaOs have a very wide range and the promise of interesting response characteristics. The following example was well characterized by a conjugate gas-flow-heat-flow model. 

An estimate of the rate of heat transfer from the ullage gas to the container walls is necessary to calculate the equivalent condensed mass. During brief periods of high gas flow, heat transfer occurs by forced convection. When the rate of constant pressure transfer is slow, a natural convection mechanism is more important. A model suggested here circumvents many of the problems introduced by the separate consideration of forced and natural convection of the pressurizing gas. It is assumed in this model that the predominant mode of heat transfer is natural convection. 

Doughty, J.R., Perkins, H.C., 1973. Variable properties laminar gas flow heat transfer in the entry region of parallel porous plates. Int. J. Heat Mass Transf. 16, 663-668. 

Set up the apparatus as in Fig. 1.3, but without the cooiing bath in place, and with a stirrer hot plate under the apparatus. Start the inert gas flow. Heat the apparatus with an eiectric heat gun (>100°C), but avoid scorching the rubber septa. Leave the apparatus to cool. 

It was noted earlier that dryers are quite difierent in character from both distillation and evaporation. However, heat is still taken in at a high temperature to be rejected in the dryer exhaust. The appropriate placement principle as applied to distillation columns and evaporators also applies to dryers. The plus/minus principle from Chap. 12 provides a general tool that can be used to understand the integration of dryers in the overall process context. If the designer has the freedom to manipulate drying temperature and gas flow rates, then these can be changed in accordance with the plus/minus principle in order to reduce overall utility costs. 

In such a plant the gas stream passes through a series of fractionating columns in which liquids are heated at the bottom and partly vaporised, and gases are cooled and condensed at the top of the column. Gas flows up the column and liquid flows down through the column, coming into close contact at trays in the column. Lighter components are stripped to the top and heavier products stripped to the bottom of the tower. 

The heat capacity of a gas at constant pressure is nonually detenuined in a flow calorimeter. The temperature rise is detenuined for a known power supplied to a gas flowing at a known rate. For gases at pressures greater than about 5 MPa Magee et al [13] have recently described a twin-bomb adiabatic calorimeter to measure Cy. 

A plasma of electrons, ions, and neutrals produced in gas flowing through concentric tubes is maintained and heated to 5000 to 8000 K by inductive coupling to a high (radio) frequency... 

WulffProcess. The regenerative technique is best exemplified by the Wulff process, Hcensed by Union Carbide Corp. The furnace consists basically of two masses of high purity alumina refractory tile having cylindrical channels for gas flow and separated by a central combustion space as shown in Figure 10. Its cychc operation has four distinct steps, each of approximately 1 min in duration, the sequence being pyrolysis and heat in one direction followed by pyrolysis and heat in the other direction. Continuity of output is achieved by paired installations. 

Fresh butane mixed with recycled gas encounters freshly oxidized catalyst at the bottom of the transport-bed reactor and is oxidized to maleic anhydride and CO during its passage up the reactor. Catalyst densities (80 160 kg/m ) in the transport-bed reactor are substantially lower than the catalyst density in a typical fluidized-bed reactor (480 640 kg/m ) (109). The gas flow pattern in the riser is nearly plug flow which avoids the negative effect of backmixing on reaction selectivity. Reduced catalyst is separated from the reaction products by cyclones and is further stripped of products and reactants in a separate stripping vessel. The reduced catalyst is reoxidized in a separate fluidized-bed oxidizer where the exothermic heat of reaction is removed by steam cods. The rate of reoxidation of the VPO catalyst is slower than the rate of oxidation of butane, and consequently residence times are longer in the oxidizer than in the transport-bed reactor. 

Quench Converter. The quench converter (Fig. 7a) was the basis for the initial ICl low pressure methanol flow sheet. A portion of the mixed synthesis and recycle gas bypasses the loop interchanger, which provides the quench fractions for the iatermediate catalyst beds. The remaining feed gas is heated to the inlet temperature of the first bed. Because the beds are adiabatic, the feed gas temperature increases as the exothermic synthesis reactions proceed. The injection of quench gas between the beds serves to cool the reacting mixture and add more reactants prior to entering the next catalyst bed. Quench converters typically contain three to six catalyst beds with a gas distributor in between each bed for injecting the quench gas. A variety of gas mixing and distribution devices are employed which characterize the proprietary converter designs. 

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