Heat preheating

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 ... 

The off-gas condenser was a shell-and-tube (water-cooled) heat exchanger a 260 liter capacity stainless steel tank was used to collect condensate and a stainless steel wire-mesh de-entrainer, a shell-and-tube (steam-heated) preheater and a HEPA filter were used in the off-gas system. 

The olefinic charge is combined with unreacted hydrogen from the second stage, and both are passed through a steam-heated preheater and then into the top of the first-stage hydn nation reactor. Here the olefin-hydrogen mixture intimately contacts the catalyst, which induces saturation of the olefinic linkage. 

The above swii can be eliminated by controlling the preheater heat duty or, better still, the preheater heat duty per unit feed flow (362), instead of the preheater outlet temperature. For steam (or condensing vapor) preheaters, the duly per unit feed flow equals the ratio of the measured steam (or vapor) flow to the measured feed flow times a constant, the constant being the steam latent heat. For a sensible-heated preheater, the above ratio is multiplied by the measured hot-side temperature difference, and the constant is the average hot-fluid heat capacity. For two or more feed preheaters, it is best to compute their total heat duty on-line and ratio it to the feed (68, 259). The computation can be readily performed using conventional analog instrumentation. Similar techniques cured the above-cited swing problems (239,259). 

A reactor system comprising one or more catalytic synthesis converters with associated temperature control and heat recovery equipment Heat exchangers for cooling the product gas to recover waste heat, preheat converter feed gas and to condense the product ammonia. 

Olefins. Olefins are the most critical higher hydrocarbons with respect to carbon formation. The rate of carbon formation is several orders of magnitude higher than for other hydrocarbons. Olefins are normally not present in the feedstock, but they could easily be formed by thermal cracking of higher hydrocarbons in over-heated preheaters (reaction (9)), or even by oxidative coupling of methane in presence of air in the feedstock (see section 4). 

Heat Preheated, liquid phase Screw plasticizing Screw plasticizing... 

However, factors such as this should not he allowed to dictate design options at the early stages of flowsheet design because preheating the cold feed hy heat integration with the rest of the process might be possible. 

Taking the heat capacity of water to be 4.3 kJ kg K , heat duty on boiler feedwater preheating is... 

The appropriate placement of reactors, as far as heat integration is concerned, is that exothermic reactors should be integrated above the pinch and endothermic reactors below the pinch. Care should be taken when reactor feeds are preheated by heat of reaction within the reactor for exothermic reactions. This can constitute cross-pinch heat transfer. The feeds should be preheated to pinch temperature by heat recovery before being fed to the reactor. 

In the expression for heating value, it is useful to define the physical state of the motor fuel for conventional motor fuels such as gasoline, diesei fuel, and jet fuels, the liquid state is chosen most often as the reference. Nevertheless, if the material is already in its vapor state before entering the combustion system because of mechanical action like atomization or thermal effects such as preheating by exhaust gases, an increase of usefui energy resufts that is not previously taken into consideration. 

The heavy fuel should be heated systematically before use to improve its operation and atomization in the burner. The change in kinematic viscosity with temperature is indispensable information for calculating pressure drop and setting tbe preheating temperature. Table 5.20 gives examples of viscosity required for burners as a function of their technical design. 

Dissolve 5 g. of aniline hydrochloride in 120 ml. of hot water contained in a 200 ml. conical flask and then add 4 g. of potassium cyanate. Heat the solution on a water-bath for 30 minutes, adding about 1-2 g. of animal charcoal towards the end of the heating if a slight turbidity has developed. Now bring the solution quickly to the boil over a gauze, and filter it at the pump, using a Buchner funnel and flask which have been preheated by the filtration of some boiling distilled water. The clear... 

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