US3461038A - Flash evaporator adjustable valve venturi inlet - Google Patents

Description

Aug. 12, 1969 c. A. LIND 3,461,038

FLASH EVAPORATOR ADJUSTABLE VALVE VENTURI INLET Fild May a, 1968 v 2 Sheets-Shet 1' FIG. I

INVENTOR.

CARLTON ADOLPH LIND ATTORVI' Y Aug. 12, 1969 c, LlND 3,461,038

FLASH EVAPORATOR ADJUSTABLE VALVE VENTURI INLET Filed May 6. 1968 2 Sheets-Sheet 2 j 20 INVENTOR. 4O CARLTON ADOLPH LIND BY A /ATTOR EY United States Patent s Claims ABSTRACT OF THE DISCLOSURE "A stagefor'multi-sta'ge flash distillation device having a venturi entrance device in which is provided adjustable valvmg means forregulating the flow of incomingbrine.

led

into steam. This steam is withdrawn upwardly from each stage and passes to heat exchangers (not shown) where it is condensed and the resulting liquid'is drawn 01f iriany well known manner. Brine which has not been evaporated passes to the next stage and is operated, on in a. similar manner.

As herein so far described the evaginated; venturi is similar in construction and operation to the .device described in detail in copending application in thename "of W. R. Williamson, S.N. 440,493 now U.S. nt, 3,41 s,j- 213 and constitutes a distinct improvement over prior ;art

devices in preventing steam blowby' and'provid ingfstable An object of this invention is to provide an evaporator stage which is more stable 'and efiicient in its operation over a Wider range of operating conditions.

Another object of this invention is to provide a brine flow control device between flash evaporator stages which will prevent steam blowby from one evaporator stage to another.

A feature of this invention is the provision of an evaginated ventun' which will compensate for pressure changes without allowing vapour to leak from a preceding stage.

A particular object of this invention is to provide a variable orifice venturi control device for use between flash evaporator stages.

Many other objects, advantages and features of invention reside in the particular construction, combination and arrangement of parts involved in the embodiment of this invention and its practice as will be understood from the following description and accompanying drawing wherein:

FIGURE 1 is a perspective view of a fragment of a multistage evaporator;

FIGURE 2 is a plan view transversely through an evaporator stage of FIGURE 1 as viewed from line 22 and showing the prefered embodiment.

FIGURE 3 is an end view of the device-of FIGURE 2 as seen from the direction indicated by the line 3-3;

FIGURE 4 shows a modification of the construction of FIGURE 1;

FIGURE 5 is a sectional plan view similar to FIGURE 2 but showing a modified construction as usedi'n FIG- URE 5;

FIGURE 6 is a transverse section taken on the line 6-6 of FIGURE 2;

FIGURE 7 is a transverse section showing still another modified construction.

The preferred form of the present invention is depicted in the figures in connection with a straight through evaporator comprising a shell 10 having a series of evaporator stages 12 formed by partitions 14 extending across the shell.

Each of the partitions 14 is provided with an inlet slit 16 along its bottom for passing fluid from one stage to the other. The fluid or brine to be flashed flows into the bottom portion of an evaginated venturi 18 formed by a partition 14 and an inclined upstanding plate 20 which ends short of the partition in a throat 22. A top plate 24 having a downwardly turned lip 26 is provided to direct the incoming fluid downwardly and across the stage 12. Each of the plates 20, 24 and 26 extend transversely across the stage.

As brine passes through the evaginated venturi it flashes and eflicient operation under normal operating conditions, However, it has been found under certain circumstances that the flow of liquid and vapor through successive stages results in pressure loss between adjacent stages adversely affecting performance ratios. We have found ithat' it is necessary to valve or gate the veut'urif openings between successive stages, adjustably, and often'to afdifferent degree to compensate for the fluid flow and lossof pressure, and have accordingly devised the followingfnovel construction to obtain this result.

Turning to FIGURE 1 the stages subsequent to the first are provided with a valve mechanism generally depicted as 28. This valve mechanism is located adjacent the throat 22 and is adjustable by manual operation to limit the flow of liquid or brine through the venturi and simultaneously create a one-way valve sealing each stage from the next adjacent one thereby limiting blowby. The pressure and fluid flow conditions of each stage may be individually controlled so as to obtain maximum flash or evaporation and operating efiiciency. It will be noted that the first stage (FIGURE 1) is shown as being without the valve mechanism 28. This is because the quantity of brine entering the evaporator may conveniently be regulated by con ventional flow control means in the main feed line (not shown) which debouches into the first evaginated venturi at the entrance port 30. However it is practical and in many cases advantageous, to use the valve of the invention at this point as will later be explained with reference to FIGURES 4 and 5.

FIGURE 2 depicts the details of the preferred'form of valve mechanism, which is mounted transversely across the evaporator shell 10 and extends from side wall 32 to side wall 34. The valve 28 comprises a cylindrical tube v 36 in which are cut a pair of oppositely disposed slots 38 and 40 extending axially from a point adjacent one end of tube 36 to a similar point at the other end of it. These slots are most conveniently bridged as at 42' to strengthen the said tube. It will be readiy seen by reference to FIGURE 6 that partial counter-clockwise rotation of the tube 36 from the position shown will restrict the effective width of slot 38 because of its proximity to the partition 14 and thus reduce the flow area therethrough. The valve may be adjusted anywhere from the full oper condition shown to substantially complete shut-off. It is also apparent that rotation in the reverse direction will have a similar effect because of the position of slot 4( relative to partition 14.

One end of the tube 36 is freely supported by a header pivot 44 which extends inwardly through wall 34 and i: secured and sealed thereto, preferably by welding. Tht other end of the said tube is rigidly fixed onto a shaft 41 having a flange 48 at its approximate mid-point and whicl is cross drilled, as at 50, for reception of a tommy-ba: or a pin wrench. A plate 52 is secured to wall 32, prefer ably by welding; it has a central aperture 54 and a fla bottomed circular recess 56, coaxial therewith. The shaf 46 is journalled in the said aperture and the flange 41 enters the said recess until one face contacts the bottom thereof while the other face protrudes slightly therefrom retainer 58' passes over the end of shaft 46 and is attached to the plate 52 by screws 60; tightening these screws clamps the flange 48 between the said retainer and the bottom of recess 56. An ring gasket 62, carried in a groove 64 trepanned in the inner surface of flange 48 serves to seal the joint at this point. With the above described construction it is possible to unclamp the flange, adjust the angular position of valve 28 and to then relock the flange, without having leakage at this point.

FIGURE 4 shows a modified form of the structure depicted'in FIGURE 2 which is particularly suited to use in the first stage of an evaporator of the type here discussed. Here the valve tube 66 is carried on a hollow pivot 68 whose head 70 is Welded to Wall 34 and is machined to sealingly mate with the coupling flange 72 of a suitablefluid line 74. The valve-tube 66 has a single slot 76 which increases in width, as shown, as it progresses axial- 1y. By this means brine entering the evaporator is substantially evenly distributed across the width thereof, the end of tube 66 remote from hollow pivot 68 is secured to another shaft 46 and its mounting is as described in relation to valve 28; the efiective opening of slot 76 may be adjusted by rotation toward or away from the adjacent end wall 10, in the manner previously described with respect to slot 38. FIGURE 5 shows the placement of the valve tube 66 in the first stage. The upstanding plate 20 may be eliminated and, as before described, the horizontal plate 24 with its down-turned lip 26 serves to direct the incoming fluid downwardly.

FIGURE 7 shows still another modification of the present device. In this construction a perforated tube 80 having a series of slots 82 is fixed to pivot 44 and located within the rotatable tube 40. By rotating tube 40 about its fixed tube the slot opening 38 is, of course, varied. The result here would be to more precisely define the valve opening.

The preceding disclosure shows that a movable valve member may be used adjacent the throat of a nominally venturi-form passage, in an evaporator of the type in case, to vary its effective flow area. Preference is given to a cylindrical valve: there are many reasons for this including ease of manufacture and installation, dynamic balance, rigidity in heavy fluid flows and so on. Also it is obvious that automatic means responsive to evaporator operating conditions may replace, or be supplemental to the manual adjustment means disclosed. Such controls are well known in the art and it is unnecessary to describe them in detail, their use is not foreign to the present invention, the scope of which is divulged in the following claims.

What is claimed is:

1. An evaporator stage for a multi-stage flash distillation device comprising a shell having at least one transverse wall, an evaginatedventuri formed by a wall. extending upward from the bottom of said shell and converging toward said one transverse wall forming a throat opening therebetween, means for introducing fluid into said venturi for dispersion into said stage, and an adjustable valve mechanism comprising a tube supported adjacent said throat having perforations within its circumferential wall to permit radial flow of fluid therethrough and means, for rotating the same from without the said shell to selectively vary the position of saidperforations with respect to said means for introducing said fluid and said throat to regulate the flow of fluid through said venturi.

' 2. The device according to claim 1 wherein said valve comprises a tube having at least two axially extending slots selectively spaced from each otherwhereby on rotation of said tube theflow of fluid therethrough and the effective opening of said throat may be varied.

3. The device according to claim 2 wherein said venturi includes a down-turned lip located transversely of the throat and substantially tangent to the tube and offering obstruction to the flow of fluid through the perforation of said tube.

4. The device of claim 1 wherein said valve comprises i a pair of perforate tubes, one within the other and situated transversely of said throat, one of said tubes being rotatable about the other and having perforations so located that they may be moved into and out of alignment with the perforations in said other tube by rotation of said one tube.

5. The device according to claim 4 wherein said slots are selectively positioned so as to vary the rate of fluid flow radial through said tube upon rotation of said tube within the venturi throat.

References Cited UNITED STATES PATENTS 2,908,618 10/1959 Bethon 202-174 3,005,468 10/1961 Erwin et a1. 251-344 X 3,161,558 12/1964 Pavelic et al 202-173 X 3,172,824 3/1965 Mulford 202-173 3,192,132 6/1965 Loebel 202-173 3,312,601 4/1967 Wilson et al 202-173 X 3,340,159 9/1967 Tidb'all et al 2037 FOREIGN PATENTS 890,339 2/1962 Great Britain.

NORMAN YUDKOFF, Primary Examiner F. E. DRUMMOND, Assistant Examiner US. Cl. X.R.

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