US1324417A

US1324417A - Karl labs esatas thunholm

Info

Publication number: US1324417A
Authority: US
Publication date: 1919-12-09
Anticipated expiration: 1936-12-09

Description

K. L. E. THUNHOLM.

EVAPORATING APPARATUS.

APPLICATION FILED AUG. 2. 1918.

1,324,417. Patented Dec. 9,1919.

KARL LABS ESAIAS THUNHOLM, 0F fiREBRO, SWEDEN.

EvAronA'rms APPARATUS.

Specification bf Letters Patent.

Patented Dec. 9, 1919.

Application filed August 2, 1918. Serial No. 247,960.

Orebro, Sweden, have invented certain new and useful Improvements in Evaporatin g Apparatus, of which the following is a spoolfication.

The evaporating apparatus which are at presenfgenerally employed for evaporating liquids coagulating at higher concentratlons are, as is well known to those skilled in the art, provided with a number of'outwardly heated, narrow tubes located vertically in a closed vessel and through which the liquid is forced from below and upward or v 1ce versa in such manner that the liquid principally flows on the inner walls of the tubesleaving the central portions of the same free 1n order that the generated steam may freelyescape and that the evaporating apparatus may thus have the highest possible capacity.

From theoretical point of view such evaporating apparatus have great advantages over other types of evaporators, but 1n several respects they have conslderable drawbacks which are due to the fact that the tube surfaces, on evaporatin such liquids that have a tendency to coagu atein concentrated condition, very soon become covered with a heat insulating deposit making it necessary from time to time to stop the work of the apparatus for removing said deposit from the tubes.

My present invention now has for its object an evaporating apparatus, principally adapted to be used for evaporating suc liquids that have a tendency to coagulate at higher concentrations, for instance waste sulphite cellulose lye, and in which, at the same time as it provides for maintaining a large total steam generating liquid surface and free escape for the generated vapors, a continuous cleaning of the heat transmitting surfaces is effected.

The apparatus consists of a closed receptacle comprising a number of compartments with double horizontal bottoms, the inner space between said bottoms forming a heatin chamber. The double bottoms are provi ed with holes in which a collaror other communicating device is located, said collar extending a certain distance into the compartment to which the bottoms belong. Through this collar the vapors generated from the liquid having the form of a horizontal layer on theupper bottoms escape to the next compartment and so on'until it leaves the receptacle through a discharge conduit. Each collar is at one place provided with a recess forming an overflow for tl18-llql11d from one compartment to the next lower compartment. On a central Vertical shaft passlng throughoutv the apparatus there are located scrapers one for each compartment, said scrapers being adapted to rotate with the shaft and to be displacedin the longitudinal direction of the same for the purpose that they may dra on the upper bottoms under the action 0 their whole weight and, thus, remove any deposits from sald' bottoms. In order to facilitate the rotation of said scrapers they are preferably provided with a number of recesses, said recesses being located in such a manner that the recesses on one arm are located at different distances from the shaft than those on the other arm, in order that those parts of the bottom which are, due to said recesses,

not acted upon by the one arm of the scraper will be acted upon by the other one. It is convenlent to locate the holes in the bottoms and also the collars zigzag. It is also suit- I able to locate the overflows at diametrically opposite sides of adjacent collars. 1

In the present apparatus the liquid is, during the evaporation, maintained divided into a number of horizontal layers of uniform thickness. During the eva oration thus a uniform lowering of the who e liquid surface takes place and currents are formed within each li uid layer from the point where fresh liquid is supplied to every point of the surface, these currents being most powerful in the direction to the point where the overflow takes place. Due to these currents the thinner liquid being supplied from above will immediately be thoroughly mixed with the more concentrated liquid on the bottom. Such a thorough and immediate mixing is especially necessary on concentrating such liquids that have a tendency to coagulate at higher concentrations, since of a form of embodiment of the apparatus shown on the accompanying drawing.

' scraper. I The apparatus is built up by a number of V sections 1 each of which forms a receptacle like body rovided with double bottoms2 and 3. Tie upper receptacle is provided with a cover 5 and the lower one with a bottom 6. Each receptacle is at its upper and lower ends provided with a surround-. ing flange 4 and, when assembled, they rest on said flanges which can be held together and tightened. in any convenient manner. Centrally in the apparatus is journaled a vertical shaft 7 located at its lower end in a bearing 8 and at its upper end in a bearing 9. The shaft is provided at its-upper end with a belt pulley 10 orany other means for imparting movement to the same. The shaft is runnin through holes in the bottoms, the holes in the different pairs of

bottoms

2, 3 being preferably located zigzag. Through the holes of each pair of

bottoms

2, 3 is inserted a tube shaped collar 22 which is tightly fastened to both bottoms. This collar extends to a certain distance above the bottom 2 and is provided with a recess 14 forming overflow for the liquid. The recesses 14= are preferably located at dia metrically opposite sides of adjacent collars. On the shaft there are located a number of scrapers 11 one for each'bottom 2. They ou ht to be made of a material which is sof ter than that of the bottoms 2 in order that the latter may not be worn out too easilyby the scrapers dragging on the same 7 during the rotation of the shaft. The

lit

scrapers are provided with recesses 12 in order to facilitate the rotation of the same, said recesses being located on one arm of the scrapers at another distance from the shaft than on the other arm in order that durin a whole turning of the scrapers, every point of the bottoms may be acted upon by the same. These recesses may be of difierent length and form on difi'erent scrapers as is shown in the drawing. The scrapers ought, in the horizontal projection, to have the shape shown in Fig. 2, according to which they are at the ends curved forward in the direction of movement in order that, on rotating against the liquid, a force component may be effected counteracting the centrifugal forcefor preventing the liquid surface from becoming higher at the periphery than nearer to the center. The scrapers are located on the shaft in such a manner that they can be freely displaced in the longitudinal direction of the same. By this arrangement the scrapers are adapted to rest freely on the bottoms 2 andact on the same with their whole weight. For this purpose their hubs are provided with a teeter? groove 13, Fig. 2 and the shaft 7 with a duced into the heating chambers between the

bottoms

2 and 3 through branch pipes 19. These pipesopen into the heating chambers at such a distance above the bottoms that the water of condensation cannot' After having flow off through the same. passed through the heating chamber and given off its heat to the liquid through the bottoms 2 the steam is led off through pipes 20 situated at the same levelas the bottoms 3 so that the water of condensation is also led olf through the same. The pipes 20 open into a discharge tube 21. The concentrated liquid is led off through tube 17 at the lower part of the apparatus.

The apparatus works in the following manner: The liquid is supplied through pipe 15 while the shaft 7 is rotated and the heating medium is introduced through the

tubes

18 and 19. The liquid rises 1n the uppermost compartment, at the same time as it partially evaporates, until a art of the same flows off through the over ow 14 and flows, through the collar 22 down on the bottom'2 of the adjacent compartment where it evaporates and so on throughout the whole apparatus. The'vapors generated are .led upward through the collars 22 without resistance and are then led off from the apparatus through the conduit 16. As stated above, the scrapers have the object of not only removing any deposits from the bottoms 2, but also to impart motion to the liquid and thus mechanically-facilitate the escaping of the steam bubbles formed at said bottoms. The liquid becomes gradually concentrated as it descends from one bottom 2 to another, and finally when it reaches the bottom 6 it has obtained the desired degree of concentration. The concentrated liquid is then discharged through conduit 17. By varying the supply of liquid and of heating medium different degrees of concentration can be, obtained. The supply of heating medium to the different heating chambers can also be varied by means of valves provided in the pipes 19.

In the case that steam is used as a heating medium the tube 18 can be fed with fresh steam, waste steam or wholly or partially with steam escaping from the conduit 16 after having been compressed so as to get higher pressure and temperature. The heating may of course also be effected by means of electrical resistances located in the heating chambers.

It is obvious that the detail constructions shown may be varied without departing from the scope of the invention.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The herein described evaporating apparatus, including a closed receptacle composed bottoms of a plurality of sections forming compartments and provided with double bottoms having openings therein, collars secured about the openings in the double bottoms and projecting thereabove into the adjacent compartment and provided in their upper edges with overflow recesses, a vertical r0.- tatable shaft in the receptacle, means ior rotating'the shaft, scrapers on the shaft for moving about the upper portion of each double bottom, the spaces between the double constituting heating chambers, means for controlling the passage of a heating agent through the heating chambers,

means for supplying liquid to the upper part of the apparatus, and means for discharging concentrated liquid from the bottom of the apparatus.

2. The herein described evaporating apparatus, comprising a closed' receptacle, a number of compartments in said receptacle, horizontal double bottoms to each compartment, a heating chamber between said double bottoms, holes through said double bottoms, a

collar assed through said holes and secured to the ottoms, said collar extending a. distance into the compartment, a recess in said collars forming overflow for the'liquid to next compartment, said collars also forming means for leading off vapors from the compartments, a central, vertical shaft through the apparatus, means for rotating said shaft, scrapers on said shaft adapted to rotate with the same and to drag on each upper bottom, recesses in said scrapers, means for supplying a heating agent to each heating are arranged in registration and the adjacent collars are, arranged in staggered relation.

4:. An apparatus as claimed in claim. 1 wherein the overflow recess in each collar is arranged at a point diametrically opposite the recess in the adjacent collar.

In testimony whereof I have aflixed my signature in presence of two witnesses.

Witnesses:

- AxEL EHRNER, JACOB Bacon.

KARL LABS ESAIAS THUNHOLMt it