partially condensed and falls in form of a fluid upon the plane a b. The vapors which have not been condensed in this chamber penetrate further through the hydraulic seal into the oil masses and stir them up, whereby a portion of the heavier vapors is condensed, while the other portion is mixed with the vapors escaping from the naphtha of the pan, and enters through the slit d the second chamber. Here the entering vapors touch the plane ef' with less heated naphtha and heat the latter, whereby they are partially condensed, while the non-condensed portion passes through the hydraulic seal p' to act in the above described manner, the process being repeated in each chamber of the apparatus. The latent heat of the vapors ascending from below to above serves for heating the naphtha, which moves in the opposite direction from above to below to the still B. The closer the naphtha gets to the still the hotter the vapors which it meets; it becomes heated, whereby the portions corresponding to the degree of heating vaporize, so that only the heavy portion of the naphtha which cannot be volatilized in the apparatus runs into the still. The direction of the passage of the naphtha is readily understood from the illustration. It enters through the pipe K, the apparatus A, spreads out upon the planes e fo, and is heated by the vapors which circulate in the second chamber and pass into the fluid through p. The naphtha then pours through the pipe K upon the plane c, f, which is heated by vapors possessing a higher temperature, and hence a proportion of the heavier fractions is here vaporized, while the other portion passes through K, to e, f, and so on. The portion which does not vaporize upon the plane e ƒ passes through the pipe K into the still B.

4

5

The distillates formed by the condensation of the vapors flow upon the plane a b and through the pipes g, to g, into tanks. The pipes g, to g,, before entering the tanks, pass an inclined cylinder which plays the role of a preparatory heater; the naphtha in going to the distilling apparatus passes this cylinder and is thus preparatorily heated by the distillate.

According to the statements of the inventors,' the apparatus possesses the following properties: It has a very small volume, consumes little fuel and cooling water, and the separation of the products of distillation is as complete as possible.

The still has a capacity of 400 pood crude oil, and with a continuous supply works up 8000 to 10000 pood crude oil in 24 hours. The specific gravity of the distillate upon the first pan is 0.872, and that of the residum 0.920; 57 per cent. of distillate is obtained. The difference in temperature between every two pans is 30° C., which for an apparatus with seven pans. would make a total difference of 210° C.

The excess of the naptha residuum runs off from the still through the pipe L. It also passes the inclined cylinder filled with naphtha and yields heat to it. The crude naphtha is forced from a tank placed at a higher level through this cylinder into the reservoir M.

The apparatus is claimed to be in successful operation in the Schibajeff refinery at Baku. It has, however, undergone material improvements, such as the construction of a cast-iron rectifying column, so that scarcely more than the idea is left of the original apparatus. In the refinery above mentioned there are five such stills. The apparatus is provided with dephlegmation and fractional cooling, and is claimed to give a beautiful, light product, the yield being several per cent. larger than with ordinary stills. Thus far the apparatus has not been used for lubricating oils.

Less satisfactory results, it is said, have been obtained in the Rothschild refinery.

Experiments have recently been made in some refineries with an apparatus for continuous distillation devised by Alexejew, but the results thus far obtained are not sufficiently definite for its practical introduction.

In this apparatus distillation of the naphtha is effected with the assistance of light hydrocarbons instead of superheated steam. The hydrocarbons used for this purpose may be formed in dis

1 Memoiren der Kaiserlich russisch, techn. Gesellsch., 1889, Mai.

tilling the naphtha or naphtha residuum, or may be produced in gas retorts of special construction. The light hydrocarbons formed during distillation pass with the distillate into the condenser, where they are separated from the oil and pumped back into the still. This mode of distillation is used for periodical as well as for continuous working. Fig. 104 shows a plant for continuous distillation.

From the still A, the vapors of the distillates and the light hydrocarbons pass through the pipe a into the first condenser

B, the distillate not condensing in the latter passing over into the second condenser C, from which the non-condensed portion enters through the pipe c the third condenser D. The noncondensed distillate passes from D through the pipe d into the fourth condenser E, and the portion which is not condensed there enters through the pipe e the coil s of the cooler F. On the lower end of the coil, as seen in the illustration, is a threeway cock g, one pipe of which is turned downward and dips into fluid 134 to 3 inches deep. Another pipe i turned upwards is connected with a gas (air) pump V which pumps the

light hydrocarbons through the pipe k back into the still A. The pipe k is furnished with fine tubes and lies like a steam coil upon the bottom of the still.

The condensers B, C, D and E, lie in the chambers G, H, I and K. These chambers, and hence also the condensers, are heated to various temperatures corresponding to the distillate desired. The closer the condensers and the chambers are to the still, the higher their temperature. Thus the first condenser B is heated to between 680° and 752° F., the product obtained being vaseline. The second condenser, C, is heated to between 5720 and 680° F., machine oil being obtained; the third, D, to between 392° and 572° F., the result being heavy oils, and the fourth, E, to between 212° and 392° F., the product being kerosene, while the vapors of benzine pass into the cooler.

The hot heating gases from the still A are conducted through the flues into the chambers, and are regulated by the dampers r. On the bottom of each condenser is a discharge pipe e, which is connected with a special cooler l. The mouth of this discharge pipe lies somewhat higher than the bottom of the condenser, so that the fluid can run off only after having attained a certain depth, the object being to give the vapors of the lighter hydrocarbons, which may have been mechanically carried along, a chance to revaporize. To obtain greater dephlegmation (a larger cooling surface), the condensers are provided with pipes. On the opposite end of the discharge pipe e is placed, slightly above the bottom of each condenser, a shoulder n, which is provided with a man-hole o and the channel p, and is also connected with the pipes b, c, d. The still A is continuously fed through the pipe S with crude oil from the reservoir L, the crude oil being pumped into the latter from the reservoir T, which is located at a lower level. The pump sucks up somewhat more oil than required for feeding the still A; the superfluous crude oil flows back through the overflowpipe u into the lower reservoir T.

To prevent the naphtha in the reservoir from becoming

heated by the pipe S, the latter lies in the cooler W. The cock Z serves for discharging the fluid from the still A.

If the apparatus is to be used for the fractional distillation of residuum only two condensers are required.

The apparatus above described is said to be in use in the Zollikofer refinery at St. Petersburg, and to yield good results; this statement being confirmed by experiments made by Alexejew in the presence of a commission of experts. However, according to private information, an apparatus in a Baku refinery has not yielded satisfactory results.

It is claimed that from naphtha residuum the apparatus yields about 80 per cent. crude kerosene of 0.824 specific gravity. With one distillation only about 30 per cent. of the crude material are obtained as kerosene in the condenser E, but if the oils condensing in the condensers B, C, D, are again subjected to distillation in the apparatus, the above mentioned 80 per cent. is obtained. This crude kerosene is then subjected to distillation in ordinary stills. The product is a good illuminating oil of 0.821 specific gravity, and amounts to about 67 per cent. of the crude material.

The Alexejew apparatus is said to work very quietly and require no attention. However, as dephlegmating chambers are required, it is much more expensive than ordinary stills, and distillation having to be repeated three times, the consumption of fuel is necessarily large. Hence it could only be introduced in regions where naphtha is expensive and fuel cheap. That the apparatus did not yield satisfactory results at Baku is very likely due to the low price of crude naphtha prevailing there, it differing but little from that of residuum, so that there is no necessity of working residuum for illuminating oil, which is the actual principle of this apparatus.

The yield of about 67 per cent, kerosene from residuum is due, however, not only to the distillation being effected with the assistance of the light hydrocarbons, but also to the quite high temperature (about 717° to 735° F.) prevailing in the still. At this temperature the heavier portions undergo a de