Condensing towers

The liquid in the jars and condenser tower may be distilled over sodium hydroxide. The recovered alcohol can be recycled. 

The gases escape through / and a valve into one of three plate-condensing towers G, and through a fan A which delivers them where required, or through a flue F. The plate towers are supplied with a solution of a copper or other metallic salt, which absorbs the last traces of phosphorus vapour. 

Tower-still coking. For many years, coking was carried out as a batch process in which reduced crude (or other heavy oil) was heated by direct fire in horizontal vessels. Because they were equipped with condenser towers, these coke stills were known as tower stills. The charge was heated until all the volatile products had been driven overhead. The layer of red-hot coke remaining in the still was allowed to cool and was then removed manually by laborers who entered the still. More-economical coking processes were later developed that operate on a continuous basis. 

In order to simulate the condensing system of an industrial vacuum pyrolysis plant which consists of two condensing packed towers continuously operating, the liquids collected in each trap were mixed and then evaporated at 45 "C during half an hour in a rota-vapour (Biichi, RE 111). The heavy fraction which remained in the flask corresponds to the oil from the first condensing tower and is called bio-oil , while the evaporated fraction which consists of water and light organic compounds corresponds to the aqueous phase of the second tower and is called "aqueous phase . 

In modern plants the condensation of phosphorus is carried out in two stages. In a first condensation tower water at 50 to 60°C is sprayed from the top and meets the phosphorus vapor being transported countercurrently from below, whereupon the pho.sphorus condenses as a liquid. The second condensation tower uses water at 10 to 25°C and solid phosphorus is formed. This is periodically melted and as with the first condensation tower run off into a holding tank. The liquid phosphorus is stored under water, drawn off and transported. 

Fig. 2 shows an air-cooled condensing arrangement made hy Doulton Co., of Lambeth, London, a is the still head, the nitric acid from which passes into a preliminary stoneware receiving vessel it, and thence into a series of air-cooled vessels 11,. C is an earthenware condensing worm immersed in a cooling tank of water, while l> are condensing towers, usually packed with glass balls or cylinders, or sometimes provided with plate columns, down which trickles water to absorb the last trace of free acid. 

Fig. 10.8. Tlie chemical wave formation and propagation of a dust slielt via dust formation at the outer edge and dust CTOporation at the inner edge. The figure shows the time evolution of the angle-averaged dust temperature (upper plot) and degree of condensation tower plot). Tire quantities are shown at seven tinie-steps.

The process gas is further cooled in the condensing tower (4) by circulating weak acid which is cooled externally in impervious graphite heat exchangers (5). Entrained droplets of acid mist are removed from the gas in electrostatic precipitators (6). Drips from the precipitators are returned to the gas cooling tower. 

The solvent evaporated in the drying chamber has to be condensed and recovered. The off-gases from the condensation tower are then reheated in an indirect heater for being reused in the drying chamber. The process is shown in Figure 4.2. 

Fig. 5.11. Concat process, (a) Reaction tower, (i>) scrubber, (c) condensing tower, (d) blowei (e) pump (f) mist sq rator...

From the Venturi washer, the gas is transferred to a condensing tower, where it is cooled by air tt> ambient temperature. The cooling air absorbs water vapour and effects a certain drying of the gas. Residual sulfuric acid vapours are condensed by spraying the gas with lean acid, which is recycled to the hot condensing stage. 

The newer VVER-440 model 213 differs from the 230 in that it has an emergency core cooling system with limited capacity and a bubbler/condenser tower which is connected with the accident localization compartments of each unit to mitigate the effects of severe accidents. This tower has a rectangular cross section and contains 12 levels of suppression pool trays (in total about 1960 trays). The tower also houses four large receiver volumes referred to as gas holders or air traps. 

If the bubbler condenser structure (walls and caps) were to fail in the initial moment of the postulated accident, then the water would flow out of its shelves into the bubbler condenser tower early after the accident. This would provide sudden steam condensation and pressure drop inside the containment, but the water would be lost from the bubbler condenser shelves and in the subsequent stages of the accident process the bubbler condenser would not be able to fulfill its safety functions. 

Reactive chemical foams were used for many years to clean equipment that cannot (or should not) stand the weight of a liquid fill, or if it is not economical to fill the equipment with liquid. Industrial process equipment that has been successfully cleaned with foam include utility surface condensers, towers, tanks, and utility power turbines. A short theory section is presented. 

Figure 8.1. Gossage-type condensing tower at Messrs. John Hutchinson and Co. (First Report of the Inspector appointed under the Alkali Act, PP. 1865 (3460), XX).

Smelter gas may occasionally contain a significant amount of fluorine—which may cause accelerated corrosion in the wet gas cleaning plant and acid plant. The corrosimi rate is significantly lowered by adding sodium silicate to the packed bed condensation tower circulating solution (Fig. 4.1 Hasselwander, 2009). 

In large condensers of the tubular type the condenser usually consists of several separate condensing units and liquid is withdrawn from each. Each of these units is referred to as a partial condenser. However, partial condensation does not give an effective separation between products, and hence it is not generally used as a method of fractionation. The partial condensers that are used in a modem vacuum plant for the separation of gas oil and wax distillate may be an exception. This separation need not be exact, and hence partial condensers are satisfactory (Fig. 7-25). In the past, dephlegmators or partial-condensation towers, cooled either by air or water, were extensively used. 

The term dephlegmator is usually reserved for partial-condenser towers, but certain cracking processes have retained this name for their fractionating towers. They have changed the process of separation but have retained the older name. 

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