US1436739A - Evaporator - Google Patents

Description

Patented Nov. 28, 1922.

STATES PATENT OFFICE.

ALFRED L. WEBRE, OI WINCHESTER, MASSACHUSETTS.

' EVAPORATOR.

Application filed March 3,

bodied. in certain constructions hereinafter described in detail, which may be applied to any of the effects of a single or multiple ef, fect evaporator, whether operating under pressure above atmospheric, or under vacuum. The objects sought'and accomplished by the invention appear from' the following description of one embodiment of the inven-' tion, and the recital of the useful results accomplished thereby set forth inthe following specification.

In the drawings, Figure 1 is an elevation,- with parts shown in section of an evaporator unit embodying my invention. Figure 2 is a sectional view showing in detail one of the elements of the eva orator unit.

The same reference 0 aracters indicate the same parts in both figures.

The unit herein described comprises an evaporator 3, a catch-all 4, a conduit 5 leading from the evaporator to the catch 'all, a return pipe 6 from the catch-all to the evap-. orator, a draw-ofl' pipe 7 from said return pipe, a level regulator 8, a discharge pipe 9 from the level regulator, and a vapor outlet conduit 10 from the catch-all.

The evaporator is constructed with an outer shell 11, in which is contained a removable tube bundle or collection of tubes 12, below which is a receiving chamber 13 and above which is a separating chamber 14. The shell 11 is preferably made of a number of tubular sections placed end to end, and having'flanges by which they are secured together, and to the endmost of which are secured respectively the bottom head 15 and the top head 16. The lowermost section has an inwardly projecting ledge 17 on which the periphery of the bottom tube sheet -18 rests, and the upper section has an inwardly projecting ledge 19 supporting an annulus 20 on which the edge of the upper tube sheet 21 ..rests. The tubes are secured at their ends in any ordinary or other desired manner in the tube sheets. The lower sheet is enough smaller in diameter than the opening within the ledge 19,. and annulus 20 to pass through 1919. Serial No. 280,374.

such opening, thereby permittingthe entire tube bundle to be withdrawn from the shell as a unit when the upper head 16 i-sremoved. When in place the tube bundle is secured by bolts which may be reached from handholes or manholes in the sides of the upper and lower sections. 7

The space in the shell surrounding the tube bundle and among the tubes is the heating space which receives steam or other heating agent, admitted through an inlet 22 in the side of the shell. An outlet 23 for the condensate of the heating agent leads from the lower part of such space, and is controlled by a valve 24. 25 represents a'supply pipe for the liquor to be evaporated, the

same communicating with an'inlet 27 in the shell below the tube bundle, and being controlled by a valve 26. Between the annulus 20 and the shell is an annular space 28, and the opening 29 in the side of the shell which registers with the conduit 5 is, as to its lowest part, on the same level with this annular space, while its upper part is above the level of the tube sheet 21. In other words, the tube sheet 'is above the annular space 28 and between the upper and lower limits of the outlet opening 29. 30 represents a guard forming a gutter which overlies the opening 29 adjacent to the shell, and

provided to exclude liquid from the conduit 10 and to insure that the fluid which passes to the conduit 10 will be exclusively or mainly'vapor. Said conduit leads either to the heating space of the effect next following in serles, 1n the cam of a multiple effect evaporator, or to a condenser or the atmosphere in the case of a single efi'ect apparatus, or of the last effect in the multiple efi'ect apparatus.

- The return conduit opens from the side of' the catch-all below the orifice of standpipe 32 and leadsinto the chamber 13 beneath the lower tube sheet of the tube bundle.

The level regulator is of ordinary construction and consists of a chamber, the.

lower. part of which is connected to the pipe 7 and in the side of which there is an outlet wherefrom the delivery pipe 9 passes. Fitting telescopically in the, rising part ofthe pipe 7 is a tube 33, the upper end of which is connected to a rod 34 passing through the top of the chamber 8 and being movable endwise. This rod is threaded in part and passes through a nut 35' supported by a bracket 36 attached to the side of the conduit 6. A gear wheel 37 is secured to the nut35 and meshes with a gear wheel 38 on a shaft 39 which is equipped with a hand wheel 40. Evidently by turning this handwheel, the nut may be rotated, and rod 34 thereby moved to raise and lower the telescopic tube 33, whereby the level of the liquid in the evaporator may be regulated, since such liquid will'not overflow the telescopic tube until its level in the evaporator is at or above the level of the upper end of this tube. 41 is an indicating pointer outside of the level regulator chamber, carried by a rod 42 which is attached to an arm 43 fixed to the rod 34.

42 represents a conduit leading from the catch-all to the level regulator to equalize the pressure in the latter with that of th rest of the apparatus.

In the evaporator there are one or more inclined baflie plates 44 through which the tubes pass and in which they fit closely. These batlles do not entirely cross the evaporator shell, but extend from near the wall of the shell to a point slightly beyond the axis, and successive bailies are oppositely located, so that their inner edges overlap. The outer edge of each baflle is lower than the inner edge, and the function of the baffles is to conduct away the water of condensation which tends to collect on the tubes and an accumulation of which would impair the efliciency of heat transmi$ion from the heating agent to the liquor. In the shell of the evaporator is an expansion joint 45 and in the conduit 6 is an expansion joint 46; the purpose of these joints being to compensate for unequal expansions and contractions of different parts of the apparatus with temperature changes. 7

In the operation of the evaporator, the liquor to be evaporated is constantly admitted through the inlet 27 It rises in the tubes 12, and is there boiled. The ebullition of the liquor causes mingled liquid and steam to be ejected from the upper ends of the tubes into the chamber 14, where a partial separation occurs, and from which both liquor and vapor pass to the catch-all 4. Preferably the inlet to the latter is tangential, so that the fluids are given a whirling motion in the catch-all, which causes cent-rifugal force to assist the separation of liquor. from vapor, The vapor then passes either to the next effect, where it furnishes make claim resides in the fact that the drawofi' outlet is located in the return conduit, so that it conducts away liquor of the greatest concentration, and before the returning liqnor has become diluted by admixture with liquor admitted through the inlet. Aside from the fact that this draw-01f pipe must be located at some point in the return conduit, the only feature limiting its position is that it must be below thelevel of the liquid in the evaporator, so that it will be filled with clear liquid, that is, the liquid which passes to it will not be mingled with vapor. Practically the most convenient point for the locatlon of this pipe is at the angle between the rising part of this conduit and the horizontal run to the evaporator.

Another feature of the invention resides in the means which prevents the collection of a body or layer of liquid over the upper ends of the tubes 12, and comprises the annular collection space 28 and the elevation of the upper tube sheet 21 above the bottom of the chamber 14. As the liquor is ejected from the tubes by the force ofthe expanding vapor, it is thrown outwardly to the walls of the chamber and most of it flows down along the walls into the annular space 28,

therefrom impeded by a superimposed layer Y of liquid, nor is a body of liquid, maintained in constant agitation by jets issuing from the tubes, as would be the case if liquid were allowed to collect above the tubes. The result is that free .flow from the tubes, without unnecessary back pressure is permitted, and that the separation between vapor and liquid becomes almost complete in the evaporator itself. Practically clear (that is not foamy) liquor flows through the lower part of the conduit 5 to the catch-all, and vapor, substantially free from liquid, flows through the upper part of the conduit. The guard or gutter 30 assists in eflecting this result by diverting the liquor which flows down the wall above the outlet 29 and preventing the liquor falling as a curtain across the outlet. Such spray or mist of the liquor as may not have "been separated in the chamber 14 is carried with the vapor into the catchall, and is there substantially entirely separated from the vapor.

When it becomes necessary to clean the tubes onthe steam side, the whole bundle,

' may be withdrawn after removal first of the top head 16. This characteristic of the invention enables the tubes to be located for cleaning, both internally, and externally, in the most convenient place or' position, and outside of the evaporator shell; and results not only in convenience to the workman, but also in avoidance of accumulation in the evaporator of the solid matter dislodged by cleaning;

It will be appreciated from the foregoing description that my invention has produced an apparatus in which there is no impedance of the evaporating action by back pressure, in which circulation of the liquor is accomplished with removal of the most concentrated liquor, and in which cleaning of the parts needing to be periodically cleaned is made possible in the most convenient and efficient way.

, lVhat I claim and desire to secure by Letters Patent is:

1. An evaporator comprising a shell, upper and lower tube sheets and conducting tu'bes fixed at their ends in said tube sheets, forming a tube bundle mounted in the shell, the space in the shell surrounding said tube bundle being a heating space adapted to contain the heating agent, an inlet for liquor in the shell below said lower tube sheet, the upper part of the shell having an annular collection space with a closed bottom surrounding the upper ends of the tubes and below such upper ends, and an. outlet from the shell communicating in part with said collectionspace and with the interior of the shell above such space, whereby liquid and vapors discharged from the tubes are conducted away from the evaporator and such liquid is prevented from accumulating over the tube orifices, and a guard or gutter connected to the wall of said shell over said outlet and extending into said collection space at each side of the outlet, to deflect liquid flowing down the wall immediately above the outlet.

2. In an evaporator a shell or casing having an inwardly directed ledge or shoulder in its upper part, an annulus supported on said ledge and rising therefrom, providing a collection space for liquid, an upper tube sheet supported on said annulus,a plurality of tubes fixed at their upper ends insaidtuloe sheet and extending downwardly therefrom, a lower tube sheet in which the lower ends of said tubes are fixed, an inwardly projecting ledge on the lower part of the shell on which said lower tube sheet is supported; an inlet to the shell below said lower tube sheet, and an outlet from the shell being in part at the level of said collection space and in part above the upper tube sheet, said lower tube sheet being smaller in diameter than the interior of said annulus, whereby the tube bundle formed by said tubes and tube sheets may be withdrawn asa unit upwardly from the shell.

3. In an evaporator an outer shell having an inlet and an outlet at different levels, a collection of substantially vertical tubes between said inlet and outlet for receiving the liquor to be evaporated, an inlet for steam as a heating agent to the upper part of the space within the shell surrounding said tubes, an outlet for condensate from the lower part of said space, and baffles arranged across the tubes arranged to deflect water of condensation from the outer surfaces of said tubes toward the walls of the evaporator. i

4. In an evaporator a shell having an inlet and an outlet in its lower and upper'parts respectively, a tube bundle comprising a collection of tubes and tube sheets in which the ends of said tubes are fixed, arranged between said inlet and said outlet, an inlet for steam opening into the space in the shell between said tube sheets, an outlet for water of condensation opening in the lower part of said space, and bafiies arranged across said bundle. with a downward inclination toward the outer walls of the shell for deflecting water of condensation adhering to the outer surfaces of the tubes.

5. In an evaporator a shell having an inlet and an outlet in its lower and upper parts respectively, a tube bundle comprising a collection of tubes and tube sheets in which the ends of said tubes are fixed, arranged between said inlet and said outlet, an inlet for steam opening into the space in the shell between said tube sheets, an outlet for water of condensation opening in the lower part of said space, and baffles arranged across said bundle with a downward inclination toward the outer walls of the of the tube bundle.

In testimony whereof I have aflixed my signature.

ALFRED L. WEBRE.

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