US3648731A

US3648731A - Underdrain

Info

Publication number: US3648731A
Application number: US92664A
Authority: US
Inventors: Derek Peter De Boerr
Original assignee: Crane Canada Co
Current assignee: Crane Canada Co
Priority date: 1970-10-26
Filing date: 1970-11-25
Publication date: 1972-03-14
Anticipated expiration: 1989-03-14
Also published as: CA967491A

Abstract

A vertically elongated body is provided at a relatively high level thereon with large openings which communicate with the upper end of central passage extending downwardly through the body to effect a high flow rate during service. Small openings at a level below the large openings communicate with an annular chamber in the lower portion of the body to effect a low flow rate during regeneration. The upper portion of the body in which the large and small openings are formed is surrounded by a tubular screen.

Description

United States Patent dc Boerr 5] Mar. M, i972 [541 UNDERDRAIN 2,085,824 7/1937 Mullett ..285/l33 R x [72] Derek Peter de Boem Toronto, 5 Ontario, Canada 2,325,464 7/1943 Bannister ..285/l33 R x Assignee: Crane Canada Limited, Montreal, Quebec.

C zmada Nov. 25, 1970 92,664

Filed:

Appl. No.:

Foreign Application Priority Data Oct. 26, 1970 Canada ..096582 US. Cl. ..ll37/550, 210/293, 285/133 R lint. Cl. i ..lE03f 3/118, B0ld 23/18 Field of Search ..210/292, 293, 279; 285/133,

References Cited UNITED STATES PATENTS 1/1899 Agge et al ..2l0/293 Primary ExaminerHenry T. Klinksiek Attorney-Fetherstonhaugh and Co.

[5 7] ABSTRACT 8 Claims, 3 Drawing Figures H/GH FLOW RATE LOW FLOW RATE I 19 Ale PATENTEDMARMIBYE 3,648,731

SHEET 1 BF 2 Ni 5 i 51$: 26 in: 26

1 P 24 g :3 J

g Q s 25 1 I 5 1 5: 1! 35 5..

2 LOW FLOW RATE 21 1,? 21 12 11 I 24 Avm 3 L I .1 f

F/GJ

INVENTOR Derek Peter deBOERR PATENT AGENTS PATENTEUHAR 14 I972 3, 648 731 SHEET 2 BF 2 IN VEN TOR Derek Peter deBOERR PATENT AGENTS UNDIERIDRAIN This invention relates to new and useful improvements in underdrains for ion exchangers utilizing a bed of solid particles to filter, soften or otherwise treat a liquid. In such apparatus the treated liquid is discharged from the ion exchange bed through a screened underdrain, and ion exchangers which facilitate a high flow rate of liquid when the. apparatus is in service. However, with this accomplished, a difficulty has arisen in obtaining .a good flow distribution when using a low flow rate of liquid during regeneration.

The principal object of the invention is to provide an improved underdrain which facilitates a high flow rate during service as well as a low flow rate during regeneration, thus affording good flow distribution over this wide range of flow rates.

Briefly, the underdrain of the invention utilizes differently sized drain openings at different levels in communication with different outlets, so that an appropriate pressure drop is available for both high and low flow rates to ensure good flow distribution.

The underdrain of the invention is very simple in construccal manufacture.

With the foregoing more important object and features in view and such other objects and features which may become apparent as this specification proceeds, the invention will be understood from thefollowing description taken in conjunction with the accompanying drawings, wherein like characters of reference are used to designate like parts, and wherein:

FIG. 1 is a vertical sectional view showing the underdrain of the invention;

FIG'. 2 is a cross-sectional view, taken substantially in the plane of the line 2-2 in FIG. 1; and

FIG. 3 is a cross-sectional view, taken substantially in the plane of the line 3-3 in FIG. 1.

Referring now to the accompanying drawings in detail, the improved underdrain of the invention is designated generally by the reference numeral and is intended .to be installed in anaperture 11 in a bottom 12 of an ion exchange bed.

The underdrain 10 comprises a vertically elongated cylindrical body 131, which may be formed from suitable plastic material, the body 13 being provided with a central longitu dinal passage 14which has a closed upper end and an open lower outlet end 14a. The upper end portion of the body 13 is formed with a plurality of relatively large high flow rate drain openings 15 which communicate with the upper end portion of the passage 14. These openings are spaced circumferentially of the body and their axes may be slanted downwardly into the passage 14, as shown in FIG. 1, so that the liquid flow through these openings blends smoothly upon entering into the passage.

The lower end portion of the body 13 is recessed to form an annular chamber 16 which surrounds the passage 14 but is isolated therefrom. Conceivably, the body 13 may be moulded with thechamber 16 therein, but as a more practical manufacturingexpedient a tubular base member 17 of plastic material may surround the recessed lower end portion of the body and coact therewith indefining the annular chamber 16. The base member 17 has its upper and lower ends suitably secured to the body 13, as by a solvent weld, for example, and an outlet port 18 is provided .at one side of the base member in commu' nication with the chamber 16. Also, an annular flange 19 may be providedintegrally on or secured to the exterior of the base member 17, the flange 19 being apertured as at 20 in FIG. 3 for reception of bolts or screws (not shown) whereby the entire underdrain 111 may be secured to the bottom 12 of the ion exchange bed.

The body 13 is also provided with a plurality of relatively small low flow rate drain openings 21 which communicate with the annular chamber 16, as will be apparent from FIG. 1. These openings are formed in what may be referred to as the intermediate portion of the body 13, somewhat above the ion exchange bed bottom 12, but definitely below the level of the relatively large high flow rate drain openings 15 which are located in the upper region of the body 13.

The portions of the body 13 in which the

drain openings

15 and 21 are formed is surrounded by a tubular screen 22 which has its upper and lower ends suitably secured to the lands23, 241 on the body, it being noted that between these lands the body is diametrically reduced so that the screen 22 is spaced radially outwardly therefrom. An annular divider flange 25is formed integrally on the diametrically reduced portion of the body 13 at a level between the high flow rate openings 15 and the low flow rateopenings 21. The flange 25 approximately divides the high flow and low flow rates through the respective drain openings, and in addition it supportably engages the .inside of the tubular screen 22. The longitudinal span of the screen between the flange 25 and the land 23 is considerably greater than that between the flange 25 and the land 24, so it is desirable to provide additional means for supporting the screen against inward collapsing by external pressure of the ion exchange bed material in the region of that greater longitudinal span of the screen. Thus, the upper portion of the body 13 between the flange 25 and the land 23 isprovided with a set of circumferentially spaced, longitudinally extending ribs 26 which are formed integrally with the bodyand supportably engage the inside of the screen, as is best shown :in FIG. 2. The aforementioned drain openings 15 are spaced so that they re located between the ribs 26, as shown.

In operation, the underdrain unit 111 is installed in the aperture 11 so that it projects through the ion exchange bed bottom 12 into the ion exchange material, substantially as shown in FIG. 1. When the apparatus isin service, the liquid to be filtered, softened or otherwise treated by the ion exchange passes through the ion exchange bed, through the screen 22 and through the large, high flow rate openings .15 into the passage 14, being then discharged through the lower outlet end 14a of that passage. However, during regeneration, the

liquid flows at a relatively low flow rate through the small openings 21 into the chamber 16, from which it is discharged through the port 18. Thus, the underdrainis effectively capable of handling both high and low flow rates as requiredbyservice and regenerating conditions, respectively, by utilizing the relatively large and

small drain openings

15, 21, respectively, at respectively higher and lower levels in the ion exchange bed, and discharging through the separate outlets 14a and 18, respectively. In this manner the required. pressure drop over the underdrain is provided for both the high and the low flow rates in order to assure good flow distribution.

While in the foregoing there has been described and shown the preferred embodiment of the invention, various modifications and equivalents may become apparent to those skilled in the art to which the invention relates. Accordingly, it is not desired to limit the invention to this disclosure, and various modifications and equivalents may be resorted to within the spirit and scope of the appended claims.

The embodiments .of the invention in which an exclusive property or privilege is claimed are defined'as follows.

1. An underdrain foran ion exchanger having a highflow rate during service and a low flow rate during regeneration, said underdrain comprising a vertically elongated body adapted to be installed at the bottom of an ionexchange bed, said body having two separate outlets and being provided at two distinct levels with two sets of differently sized openings communicating with the respective outlets, one set of said openings beingrelativelylarge high flow rate openings located at a relatively high level, and the other-set being relatively small low flow rate openings located at a level substantially below the large openings.

2. An underdrain for an ion exchanger having a high flow rate duringserviceand a low flow rate during regeneration, said underdrain comprising a vertically elongated body provided with a central longitudinal passage having a closed upper end and .an open lower end, the lower end portion of said body being shaped to form an annular chamber which surrounds said passage but is isolated therefrom, said chamber having an exteriorly communicating port, the upper portion of said body being provided with a set of relatively large high flow rate openings communicating with the upper end portion of said passage, said body also being provided with a set of relatively small low flow rate openings communicating with said annular chamber, said low flow rate openings being disposed at a level on said body substantially below said high flow rate openings.

3. The device as defined in claim 2 together with a tubular screen secured to and surrounding the upper portion of said body in which said high flow rate and low flow rate openings are provided.

4. The device as defined in claim 3 together with a set of circumferentially spaced vertical ribs provided on the upper portion of said body and supportably engaging the inside of said tubular screen.

5. The device as defined in claim 3 together with an annular divider flange provided on he upper portion of said body at a level between said high flow rate and low flow rate openings, said divider flange engaging the inside of said tubular screen.

6. The device as defined in claim 2 together with a tubular base member secured to and surrounding the lower end portion of said body, the latter being formed with an annular recess which coacts with said tubular base member to define said annular chamber.

7. The device as defined in claim 6 which is further characterized in that said port of said chamber is provided in said tubular base member.

8. The device as defined in claim 6 together with an annular mounting flange provided exteriorly on said tubular base member.

Claims

1. An underdrain for an ion exchanger having a high flow rate during service and a low flow rate during regeneration, said underdrain comprising a vertically elongated body adapted to be installed at the bottom of an ion exchange bed, said body having two separate outlets and being provided at two distinct levels with two sets of differently sized openings communicating with the respective outlets, one set of said openings being relatively large high flow rate openings located at a relatively high level, and the other set being relatively small low flow rate openings located at a level substantially below the large openings.

2. An underdrain for an ion exchanger having a high flow rate during service and a low flow rate during regeneration, said underdrain comprising a vertically elongated body provided with a central longitudinal passage having a closed upper end and an open lower end, the lower end portion of said body being shaped to form an annular chamber which surrounds said passage but is isolated therefrom, said chamber having an exteriorly communicating port, the upper portion of said body being provided with a set of relatively large high flow rate openings communicating with the upper end portion of said passage, said body also being provided with a set of relatively small low flow rate openings communicating with said annular chamber, said low flow rate openings being disposed at a level on said body substantially below said high flow rate openings.

5. The device as defined in claim 3 together with an annular divider flange provided on the upper portion of said body at a level between said high flow rate and low flow rate openings, said divider flange engaging the inside of said tubular screen.