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The production of columns with valved plates was begun in 1965. A preliminary estimate of economic efficiency from use of columns with valved plates instead of bubble cap plates showed that the main econom- ic effect is about 400,000 rubles per 1000 tons of column ap- paratus. Industrial tests of an atmospheric column with valved once-through plates for petroleum distillation, carried out in 1966 in the Syzransk petroleum refining factory, confirmed their high efficiency and productivity. Besides the increase in pro- ductivity and quality of products obtained, the selection of light petroleum products has been stably increased also (2-4%). The "Giproneftemash" has developed and introduced into industry mesh-work grid plates of the downflow type. The plate, made up of separate sections, is a flat grid which completely 444Zd I ";§ Plate and baffles Fig. 9. Sieve plate with baffle elements. spans the whole column cross-section. The dimensions and constructions of grid plates (see Table 4) depend on a number of factors, the chief of which are the proper- ties of the medium beIng separated, productivity, ten- dency of the mixture being separated toward deposit formation, change in loads In the column, etc. A sub- sidiary standard has been developed by the "Gipro- neftemash" for these plates which permits making col- umns with grid plates of diameter up to 2.4m, with varying numbers and sizes of slots. To ensure correct choice of grid plate columns, the "Giproneftemash" has worked out a method for their hydraulic design. The efficiency of grid plates fluctuates from 0.2 to 0.6 and depends on the physical properties of the media being interchanged and the following constructional features: free cross-sectional area of plates, slot widths and spacing between plates. Industrial studies of grid plate column operation showed that their productivity is 20-100% greater than that of bubble cap columns, and the pressure drop is 40% less. The greatest efficiency in increasing productivity can be obtained in columns of large diameter at a high liquid load. Thus, equipping the TsGFU plant with grid plate columns instead of bubble cap col- umns gave about 1 million rubles saving. In Fig.8 we have shown the region of stable operation for grid plates. As is evident, these plates have high productivity and a relatively low operating range; therefore use of columns with such plates under significant load fluctuations is not expedient. During the period of investigation, four characteristic schedules of plate operation were estab- lished. The first schedule pertains to the case of very insignificant vapor velocities; here the contact between vapor and liquid is not thorot{gh, and liquid and vapor pass through one and the same slot. When the velocity of the vapor stream on the plate is increased, a layer of liquid is formed, through which the vapors bubble. The transition to this schedule is characterized by a significant increase in hydraulic resistance. Further increase in the velocity of the vapor stream leads to the condition that vapor passes through one slot and liquid runs off from the plate through another. Distribution of liquid on the plate is undetermined and varies with time. The most characteristic feature of the operation of grid plates is the arising of wave-like liquid motion on them (in the horizontal direction); on further load Increase, column flooding sets In. About 1000 tons of columns with grid plates are made up annually in the petroleum refining and petrochemical industry. Use of these columns instead of channeled ones saves annually about 400 tons of metal, or 250,000 rubles. In 1966 industrial tests were completed on columns with sieve plates having baffle elements, of the "Giproneftemash" design; these were conducted in the Novo-Ufimsk petroleum refining factory, the XXII Party Conference factory, the II'ich factory (at Zdanov) and in the Omsk petroleum refining factory. Results of the tests conducted showed good operational qualities of vacuum columns with the plates cA:c 60O0 ~000 2 ,,,.J $ ~ ~ 30 Lv ' m /m~h Fig. 10. Region of stable op- eration of sieve plates with baffle elements. 1) Line of maximum allowable load; 2) line of minimum allowable toad. indicated. At the present time sieve plates with baffles are set up in a number of column projects of petroleum refIning factories, among them also in a vacuum column of 9 m diameter - in the largest domes- tic AVT-6 establishment. Sieve plates with baffle elements are made up of cross-sectionally drawn sheetingwith slots locatedin a checkerboard order. The axes of the slots are lined up at an angle to the plane of the plate (see Fig.9). Under the plate base, at an angle of: 50-70 ~ to its plane, are set up baffle elements of the same material, with the direction of slots down- ward to the side of the base. For return flow of liquid from one plate onto another, overflow set-ups of the usual construction are provided. During the time of column operation, liquid from the overflow pocket enters on to the plate base is picked up by the vapors, which have high velocity in the slots, and passes together with them onto baffle ele- ments. Because of the direction of the slots downward, the liquid overflows through the baffles on their outer side and is directed toward the plate base, where it is picked up by the rising inclined vapor stream and again passes onto baffle elements placed per- pendicularly to the vapor stream. Thus, the contact zone of vapor and liquid on the plate is comparable to the area of the plate base, multiplied by the height of the baffle elements. Vapors, arising from the next low plate through the slots in its base, change their direction cor- responding to the direction of the slots. Because of the slope of the baffles, vapors are directed upward. Thereby the liquid is separated from the rising vapor stream by centrifugal forces; the vapors pass out into the next higher plate, and the liquid through a return flow assembly descends onto the plate located below. For plates of this type the "Giproneftemash" has worked out a subordinate standard which in- cludes single- and double-stream plates with diameters from 1 to 8 m. The active section of the plates is about 14%. Characteristics of the plate are given in Tables 5 and 6. Industrial tests of a vacuum column of 3200 mm with sieve plates and baffle elements, carried out in the Omsk petroleum refining plant, showed that its productivity is approximately 3 times as great as that of bubble cap plates. Besides this, the hydraulic resistance of sieve plates with baffles, and also their metal content, is twice as small as in bubble cap columns.