Robert evaporator

Vertical Type.— Figure 12 The first vertical tube evaporator was built by Robert, and has the one great advantage over the horizontal type, that it can easily be cleaned with any ordinary flue cleaner. Figure 13 The same construction as the Robert evaporator with an addition of a very large downtake in the center to improve the circulation of the liquor. This type was first constructed by Claassen, and is now used to a large extent in the cane-sugar and malt-extract industries under the name of Standard Evaporator. ... 

The short-tube vertical evaporator. Fig. %(d), also known as the calandria or Robert evaporator, was the first evaporator to be widely used. Tubes 4 and 8 long, often 2" to 3" in diameter, are located vertically inside a steam chest enclosed by a cylindrical shell. The early vertical tube evaporators were built without a downcomer but did not perform satisfactorily, so the central downcomer appeared very early. There are many alternatives to the center downcomer different cross sections, eccentrically located downcomers, a number of downcomers scattered over the tube layout, downcomers external to the evaporator body. 

The slanted mounting of the tubes leads to a lower hydrostatic liquid height (hydrostatic pressure), therefore, to a lower liquid content with respect to the evaporation rate and a higher heat transfer than the Robert evaporator [7.21]. 

Forced circulation of the solution is guaranteed by a circulation pump and leads to an increase in heat transfer at lower difference between wall temperature and boiling point. Usually the evaporation section is shifted into the vapor space to reduce incrustation of the heating area, cleaning and maintenance are simpler than with the Robert evaporator, Z 1500-4000 mm, d 20-60 mm, Z/d 30-60, /I 100-900 m dj 1500-2500 mm [0.6], k 900-3(XK) W/(m k), to calculate the heat transfer see [7.21]. 

The contrihiition of Robert W. Norris, Robert W. Norris and Associates, Inc., to material that was used from the sixth edition is acknowledged. (Evaporative Cooling)... 

The science of chemistry languished until Robert Boyle—a brilliant, fanatically religious man—wrote The Sceptical Chymist in 1661. He gave scientists a new way of seeing the world by defining an element as any substance that could not be broken down into a simpler substance, an idea that closely coincides with todays notion of an element. Boyles insight led chemists into their labs, where they heated solids and evaporated liquids and analyzed the gases that boiled off and the residues that remained behind. They isolated a flood of new elements. 

The use of vertical tubes is associated with Robert, and this type is sometimes known as the Robert or Standard Evaporator. A typical form of vertical evaporator is illustrated in Figure 14.18, in which a vertical cylindrical body is used, with the tubes held between two horizontal tube plates which extend right across the body. The lower portion of the evaporator is frequently spoken of as the calandria section shown in Figure 14.19. Tubes... 

Fig. 19. Heats of adsorption of hydrogen on evaporated tungsten films at 23°C. in comparison with the results of Roberts (points) and of Frankenburg (broken line) as a function of surface covered.

The ideas of Wheeler that condensation and evaporation occur within a center core during adsorption and desorption and that an adsorbed film is present on the pore wall has led to the proposal of various methods for pore size analysis. In addition to the methods of Pierce and the BJH technique, other schemes have been proposed, including those by Shull, Oulton, Roberts, Innes, and Cranston and Inkley. These ideas are all based upon some assumption regarding the pore shape. 

Many arguments have been adduced for the cleanliness of the metal surface obtained by evaporation (31). In particular, it is found that (a) Robert s heat of adsorption data for W filaments agree with those of Beeck... 

Several types of evaporators exist.34 The older, more traditional, evaporators are the Roberts and the Kestner, both rising film, tubular evaporators. The Roberts, first introduced in the 1800s, is known as a short tube, natural circulation, vertical tube evaporator. The tubes, inside which the evaporation takes place, are in the range of 1.5 to 3 meters in length. The Kestner evaporator consists of numerous long vertical tubes, 6 to 7.5 meters long, inside a cylindrical shell. In both, the juice to be concentrated is fed to the bottom of the tubes and heated, causing the juice to... 

A solution (or slurry) of the sample is refluxed for 4h. A sample/reagent ratio of <0.01 is recommended. The boiling point of the dioxane-water azeotrope (81.6% dioxane) is 87.8°C. Losses of solvent due to evaporation during the treatment should be avoided (Susarev and Guseva 1964, Froment and Robert 1970). (Note 1). 

Summary ADN can be prepared directly form ammonium carbamate by first, reacting the carbamate with nitronium tetrafluoroborate in the presence of acetonitrile to form an intermediate, the free acid of ADN, which need not be isolated. This intermediate is then treated with an alcoholic solution of ammonia in the presence of ether. The ADN, is then recovered by evaporation of the reaction mixture, followed by treatment with a solvent mixture, to remove impurities. The product is recovered by evaporation, and then reciystallized from butanol to form high purity ADN. Commercial Industrial note For related, or similar information, see Application No. 539,647, June 18th, 1990, by SRI International, to Jeffrey C. Bottaro, Mountain View, CA, Robert J. Schmitt, Redwood City, CA, Paul E. Penwell, Menlo Park, CA, and David S. Ross, Palo Alto, CA. Part or parts of this laboratory process may be protected by international, and/or commercial/industrial processes. Before using this process to legally manufacture the mentioned explosive, with intent to sell, consult any protected commercial or industrial processes related to, similar to, or additional to, the process discussed in this procedure. This process may be used to legally prepare the mentioned explosive for laboratory, educational, or research purposes. 

People have been experimenting with nitrous oxide as a curiosity for the past two hundred years. Its effects, which come on within seconds, last as long as the gas is breathed, then disappear suddenly when it is slopped. Artists, writers, and philosophers have breathed nitrous oxide over and over in pursuit of elusive insights — revelations that seem overpowering under the influence of the gas, but which evaporate as soon as normal consciousness returns. When the English poet laureate Robert Southey tried the gas at a nitrous oxide party in London in the 1790s, he com-... 

Harkins and Roberts showed that the ratio of the molar total surface energy to the molar internal latent heat is not constant. It increases with temperature and is greater for very unsymmetrical molecules than for symmetrical molecules. With uns3rmmetrical molecules, the work spent in removing the molecule from the surface is a large fraction of the total energy of evaporation. If I a is the total surface energy per molecule, U the internal heat of evaporation per molecule,... 

In his lecture Taylor emphasised both the phenomenological similarities and differences that existed between adsorption processes on technical catalysts and those observed with idealised catalysts produced by the Beeck evaporated film method to form oriented or non-oriented metal surfaces. These were inherent to the two schools of surface chemistry that had emerged, there were those who studied technical catalysts (Eucken, Emmett, Brunauer) and those who favoured the clean surface approach, where particular attention was given to vacuum conditions and surface preparation and exemplified by Beeck in Emeryville and Roberts in Cambridge. Kinetic studies were dominant with Trapnell, Tompkins and Kemball following the evaporated film approach in the 1950s and sixties. " ... 

Sarkari, M. Brown, J. Chen, X. Swinnea, S. Williams, I. Robert, O. Johnston, K.P. Enhanced drug dissolution using evaporative precipitation into aqueous solution. Int. J. Pharm. 2002, 243 (1-2), 17-31. 

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