US2747682A - Strainers - Google Patents

Description

May 29, 1956 Filed Nov. 17, 19

F/GJ.

J. H. GIBSON 2,747,682

STRAINERS 53 2 Sheets-Sheet l J. H. GIBSON STRAINERS May 29, 1956 2 Sheets-Sheet 2 Filed NOV. 17, 1953 F/GZ.

Inventor Zzmmvra.

Horney STRAINERS JohnI-Iendry Gibson, Wallington, England,- a'ssignor' to Dewran'ce & Co. Limited; London, England-a'ritish company Application November 17, 1953,Serial No. 392,691

Claims priority, application Greatllrifain November 17, 1952 4 Claims. (c1. 18s- 34) This invention relates to strainers suitable for use in steam lines. In high pressure high temperature steam lines the effective removal of foreign matter such as scale and welding beads is of considerable importance. A

strainer for such service is required to operate reliablyl over long periods of time and to deal with steam flowing at considerable velocity. The pressure drop'throughthe strainer should be as low as possible and provision should be made both for the removal of collected matter and for giving access to the strainer. At the same time leakage of high pressure steam must be avoided. The main object of the invention is the provision of improved strainers suitable for use in high pressure steam lines.

The features of novelty characterising my invention are pointed out in the claims annexed to and forming part'of the present specification. The above andfurther objects and advantages of the invention will be apparentfromA the accompanying drawings and from the subsequent description relative thereto in which I have illustrated and described a preferred embodiment of my invention.

The invention will now be described, by way of example, with reference to the accompanying, partly diagrammatic, drawings in which:

Figure l is a longitudinal sectional elevation of a strainer;

Figure 2 is a View, to a relativelyzlarger scale, of afragment of perforated dat metal platefrorn which the strain ing means of Figure l is formed;

Figure 3 is a fragmentary sectional View taken on the line Ill-HI of Figure l;

Figure 4 is a fragmentary sectional view taken von thc line 'lV-IV of Figure 3; and' v Figurev 5 is a cross-Asectional'view, to a relatively larger scale, of a shot-packing ring associated with the strainer.

The strainer illustrated in the drawings is adapted for use in a high pressure steam line and includes an elongated ferritic steel body 1 formed with an inlet passage 3, an outlet passage 5 and a part 7 of increased internal diameter, which extends intermediate the inlet and outlet passages. The outer extremity of each of the passages 3 and 5 is adapted for welding the body 1 into a pipe line.

Extending axially within and spaced from the intermediate part 7 of the body is a straining means in the form of a perforated sleeve 11, the end of which nearer the inlet passage 3 is closed by an outwardly dished, imperforate deflector plate 13 which is secured to the sleeve by means of a butt weld 15, the end of the sleeve adjacent the outlet passage 5 being open. The sleeve is frusto-conical in shape, tapering from the open towards the closed end thereof so that the radial width of the annular gap 19 formed between the sleeve and the intermediate part 7 of the body decreases uniformly from the closed to the open end of the sleeve.

in order to withstand corrosion the sleeve 11 is of stainless steel and, as shown in Figure 2 the sleeve is formed of plate 21 provided with rows of perforations 23 in the form of circular holes, the perforations of succesr sive rows being in staggered array. The use of straining means in the formv of a sleeve enables a large flow area through the straining means to be provided in order that the'strainer willV operate with only asmall pressure drop. Thusthe total flow-area through the perforations is approximately twice as great as the cross sectional area of the outlet passage 5.

An annular support member 25 engages within the open end Vof the'sl'eeve,` the sleeve being secured to the member 25: by means of a Weld 27. The member 25 Vis formed with anaxially extending annular part 29 of reduced diametery which fits withina seating 31 formed in the body between the outlet passage 5 and the intermediate part 7.

Adjacent the deilector plate 13, the sleeve`11 is provided' with an auxiliary support 33 whichV includes a ring 35 and a bracket 41. The ring 35 surrounds the sleeve, is tack welded thereto andprovides'an impact surface 37 which serves to arrest particles carried from a region in the neighbourhood of the wall of theinlet passage 3 and which is disposed above 'aisump 39 for the collection of particles separated from the steam ow, the body and the sleeve extending in asubstantially horizontaldirection and the ring 35 having an external diameter slightly greater than the-internal diameter of the inlet passage. The bracket 41 is of cranked form and has a`rectangular cross section, An end portion 43 of the bracket is provided on opposite sides with ` notches 45 and 47, the bottoms of ywhich lie on arcs of a circle'and engage within a circular hole 49 formed in a complementary part 51 projecting from the' ring 35i The hole49 connects with the edge 53 of the part 51by a-slot 55 having a width equal to or slightly greater than the Width of the rectangular portion 43.' During'assembly ofthe auxiliary support 33 the portion 43 of the bracket is passed through the slot 55 andthe bracket is rotated through 90 so that the cornplementary part 51 engages thenotches 45 and 47, the bracket 41 and ring 35 thereby being locked together, and the lower end 57 of the bracket engagesf'the inner surface of the sump 39 to which it is then tack'welded.

The` sump 39 for the collection of particles isin the form of a branch secured by means of a weld'67` to the body 1.` The branch is inclined from its inner to its outer end in the direction of the outlet passage'S at an angle of about 460" to the longitudinal axis of the body and communicates with the intermediatepart 7 of the body over a substantial part of the length of the sleeve 11. The end of the branch remote from the body is closed by a removable cover member 67 and the diameter of the branch is sufficient, upon removal of the cover member 67, to permit withdrawal and replacement of the sleeve 11 therethrough. Removal of the member 67 also permits evacuation of particles from the sump and the cover member is adapted to be pressed by uid pressure within the body against a shot packing ring 69, disposed within an annular cavity 71 formed between an outer part of the member 67 of reduced diameter and the inner surface of the branch, the ring 69 being supported by an abutment ring 73 formed in segments to permit withdrawal thereof and fitting within and projecting radially inwards from a recess 77 formed in the inner surface of the branch. An outer cover plate 79 ts against the end of the branch and includes an inner annular extension 81 fitting within the removable ring 73 to maintain the segments thereof in position within the recess 77. The cover plate 79 is held in position against the outer end of the branch by means of a stud bolt 83 projecting from the cover 67, extending through a hole 89 in the cover plate and provided with a washer 93 and clamping nut 91.

A blow-down opening in the form of a bore 101 extending through the wall of the branch is provided for the evacuation from the sump of collected particles and Patented Ma'y 29, 1956' comprises an inner part 103 communicating with the lowermost portion of the sump 39 and an outer part 105 of enlarged diameter arranged to receive the upper end of a short pipe 107 which is secured to the branch by a weld 109. The lower end of the pipe 107 is adapted for connection to a valve controlled blow-down pipe as indicated by the dotted lines in Figure 1.

The shot packing ring 69 is of suitable known form and, as shown in Figure 5, comprises two channel- shaped rings 113 and 115 of a suitable composition including asbestos, contained within a thin metal sheath 116 and affording annular recesses 117 and 119 which together form an annular cavity 121. Fitting within the cavity is a further thin metal sheath 122 of copper or the like ductile metal containing a charge 123 comprising nickel shot and graphite dust. Suitably, a shot packing ring of the form described and claimed in the United States Patent No. 2,634,995 may be used as an alternative to the shot packing ring 69.

During operation of the strainer, at least some of thc particles carried by steam iiowing through the inlet passage 3 of the body 1 are arrested by striking the deector plate 13 and the impact surface 37 of the ring 35 and subsequently fall into the sump 39. Other particles are separated from the steam flow by the straining action of the sleeve 11 which is largely screened from particles by the deector plate 13 and the ring 35.

The change of direction and relatively low ilow velocity in the annular gap 19 favour` further separation of particles and the strainer 11 is eifective in preventing passage of any but small particles to the outlet passage 5.

Owing to its length and the ample tlow area through the perforations of the sleeve, to the adequate space for the flow of steam between the sleeve and the body and to the continued flow of steam in the same general direction, the strainer' operates with a very moderate pressure drop.

The stainless steel perforated sleeve 11 is suitable for use with high pressure high temperature steam and access is readily had to the interior of the body for effecting cleaning or replacement or repair of the sleeve.

What is claimed is:

l. A strainer suitable for a high pressure steam line, comprising a body formed in one piece and having an inlet and an outlet coaxial with the inlet, deecting means in the path of uid flowing from the inlet; a perforated sleeve downstream of the deecting means which is disposed within and is spaced from the body and extends axially between the inlet and the outlet, the end of the sleeve nearer the inlet being closed and the end thereof nearer the outlet being open; a sump for the collection of particles separated from the iluid flow by the deecting means and in the form of a branch which communicates with the interior of the body, is provided at the end thereof remote from the body with a removable cover, and is inclined to the common axis of the inlet to and outlet from the body from the inner end of the branch to the outer end thereof in the direction of the outlet from the body, the branch being formed so as to permit insertion and withdrawal of the sleeve therethrough; and a valve controlled blow-down pipe communicating with the interior of the sump.

2. A strainer suitable for a high pressure steam line, comprising a body formed in one piece and having an inlet and an outlet coaxial with the inlet; a perforated sleeve which is disposed within and is spaced from the body and extends axially between the inlet and the outlet, the end of the sleeve nearer the outlet being open, deflecting means located upstream of the sleeve and including an imperforate plate closing the end of the sleeve nearer the inlet, towards which end the sleeve tapers, and presenting to the inlet a convex surface; a ring surrounding the sleeve spaced from the inlet and serving to provide an annular impact surface; and a sump for the collection of particles separated from the iuid flow by the deflecting means and in the form of a branch which communicates with the interior of the body and is provided at the end thereof remote from the body with a removable cover, the branch being formed so as to permit insertion and withdrawal of the sleeve therethrough.

3. A strainer as claimed in claim 2, wherein the external diameter of the annular impact surface is approximately equal to the internal diameter of the inlet.

4. A strainer as claimed in claim 2, wherein the total ow area through the perforations of the sleeve is approximately twice as great as that through the outlet.

References Cited in the tile of this patent UNlTED STATES PATENTS 428,954 Robertson May 27, 1890 558,984 Potter Apr. 28, 1896 678,702 Vogt July 16, 1901 1,772,023 Andrews Aug. 5, 1930 2,162,043 Westlund et al. June 13, 1939 2,669,321 Schmidlin Feb. 16, 1954 FOREIGN PATENTS 274,228 Switzerland Aug. 1, 1950 435,361 Italy May 17, 1948

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