US3848624A

US3848624A - Self-cleaning valve for refrigerating apparatus

Info

Publication number: US3848624A
Authority: US
Inventors: R Banike
Original assignee: Hollymatic Corp
Current assignee: Hollymatic Corp
Priority date: 1972-09-29
Filing date: 1972-09-29
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19
Also published as: AU5688273A; DE2335130A1; JPS4971539A; AU466420B2; GB1421837A; FR2201413A1

Abstract

A refrigerating apparatus having a self cleaning valve for use with a liquid refrigerant such as carbon dioxide which exists when the pressure is released only briefly as a liquid and primarily both as a solid and a gas. The valve is self-cleaning in that opening and closing the valve dislodges solid carbon dioxide from the interior which would normally clog a valve with a liquid refrigerant of this type and with the self-cleaning feature comprising a knife edged scraping portion on either the valve seat part or the movable part so as to dislodge deposited carbon dioxide or similar refrigerant solid when the valve is operated. The disclosure also includes an apparatus including means for introducing the fluid refrigerant through a plurality of flow paths that span substantially the full width of a refrigerant chamber and with a self-cleaning valve of the above type positioned in each flow path and primarily exteriorly of the chamber.

Description

[451 Nov. 19, 1974 SELF-CLEANING VALVE FOR REFRHGERATING APPARATUS [75] Inventor: Ronald A. Banike, Elmhurst, Ill.

[73] Assignee: llollymatic Corporation, Park Forest, 111.

[22] Filed: Sept. 29, 1972 [21] Appl. No.: 293,408

[52] US. Cl 137/242, 62/62, 62/384,

137/542, 239/117 [51] Int. Cl. lFl6k 25/00, F25d 3/12 [58] Field of Search 62/303; 137/238, 242;

222/148; 239/114, 117, 123, 118; 251/172, 334, DIG. 4, 205, 333; 431/122 [56] References Cited UNITED STATES PATENTS 613,623 11/1898 Dolan 137/242 1,210,799 l/l9l7 Hawxhurst et al... 137/483 X 1,502,448 7/1924 Tanner 251/205 X 1,825,378 9/1931 Wilson 251/333 X 2,738,159 3/1956 Fleming 251/333 2,759,336 8/1956 Seefeldt 137/243 X 3,056,575 10/1962 Mooney.... 251/172 3,410,521 11/1968 Sowers et al 251/172 X FOREIGN PATENTS OR APPLICATIONS 210,530 2/1924 Great Britain 251/172 Primary Examiner-William R. Cline Assistant ExaminerRichard Gerard Attorney, Agent, or Firm-Hofgren, Wegner, Allen, Stellman & McCord 5 7] ABSTRACT A refrigerating apparatus having a self cleaning valve for use with a liquid refrigerant such as carbon dioxide which exists when the pressure is released only briefly as a liquid and primarily both as a solid and a gas. The valve is self-cleaning in that opening and closing the valve dislodges solid carbon dioxide from the interior which would normally clog a valve with a liquid refrigerant of this type and with the self-cleaning feature comprising a knife edged scraping portion on either the valve seat part or the movable part so as to dislodge deposited carbon dioxide or similar refrigerant solid when the valve is operated. The disclosure also includes an apparatus including means for introducing the fluid refrigerant through a plurality of flow paths that span substantially the full width of a refrigerant chamber and with a self-cleaning valve of the above type positioned in each flow path and primarily exteriorly of the chamber.

2 Claims, 4 Drawing Figures SELF-CLEANING VALVE FOR REFRIGERATING APPARATUS BACKGROUND OF THE INVENTION A refrigerating system of the type using a liquid refrigerant that exists principally as a solid or a gas when pressure is reduced with a typical refrigerant being liquid carbon dioxide is disclosed in the copending application of R. C. Wagner Ser. No. 264,133, filed June 19, 1972 and assigned to the same assignee as the present application. A typical refrigerant for such a system is liquid carbon dioxide which exists only briefly as a liquid when pressure is reduced and exists primarily as a mixture of a solid and a gas. Valves used to control the flow of the refrigerant in such a system are subject to complete blockage of flow by the solid refrigerant packing the inside of the valve. One of the features of this invention is to provide a refrigerating apparatus including a self-cleaning valve where such blockage is prevented.

The most pertinent prior art of which applicant is aware is US. Pat. No. 2,759,336 in which there is disclosed a valve for controlling the flow of liquid carbon dioxide and which is self-cleaning in one embodiment by a closing action over large surface areas between a movable part and a stationary part. In the present application the self-cleaning feature instead of utilizing a closing action over a large area functions by a scraping action by providing a scraping portion on one of the valve parts with the result that the self-cleaning is much more reliable and is faster acting.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a shortened horizontal sectional view through an insulated freezing tunnel of a refrigerating apparatus of the type disclosed in the above copending application and which is similar to FIG. 4 of this copending application FIG. 2 is a longitudinal sectional view through a valve embodying the invention.

FIG. 3 is a schematic flow diagram for providing liquid carbon dioxide to three of the valves of FIG. 2 in parallel.

FIG. 4 is an enlarged detail sectional view of the valve of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT As disclosed in FIG. 1 and in greater detail in the above copending application the refrigerating apparatus which is disclosed for use with liquid carbon dioxide or similar refrigerant that exists primarily under reduced pressure as a solid and a gas comprises a tunnel 11 having thermally insulated walls 12. The tunnel has an entrance end 13 and an exit end 14 through which articles as indicated at 15 are conveyed during refrigeration thereof such as for freezing food items. The conveying is accomplished by an endless conveyor belt 16 that is continuously moved in the direction indicated by the arrow 17 from the entrance 13 to the exit 14 during which the articles 15 are frozen, all as described in greater detail in the above copending application.

The gaseous refrigerant which is formed by the volatilizing of theliquid refrigerant and the sublimation of the solid refrigerant is recirculated over the articles by a gas recirculation blower l8 driven by a shaft 19 with the recirculated carbon dioxide gas being drawn from beneath the trailing end 20 of a recirculation baffle 21 and up through a conduit section 22 as indicated by the arrows 23 and into the entrance 24 to the blower 18.

At the exit 25 from the blower 18 there are provided

parallel baffles

26, 27 and 28 operating as guide means spaced from each other and having inner ends 29 spaced from each other to provide a plurality of flow paths 30, here three, spanning substantially the full width of the tunnel 11 to distribute the refrigerant across this full width.

In order to provide fresh refrigerant to the apparatus 10 the inner ends of the flow paths 30 between the baffles 29 and adjacent the blower 18 are provided with a plurality of refrigerant valves 31. As can be seen from FIG. 1 each flow path 30 at its entrance which is adjacent the blower 18 is provided with its own valve 31. Also it is possible to use a single valve 31 with a horn of the type shown in the above Wagner application to spread out the flow across the tunnel 11.

With this arrangement the fluid refrigerant which includes flowable vaporizable solid particles and gaseous fluid where the refrigerant is carbon dioxide or the like is introduced into the apparatus tunnel or chamber 11 at an intermediate section between the entrance l3 and the exit 14. Because of the positioning of the valves 31 the refrigerant is introduced initially transversely to the chamber 11 and then is turned through 90 by the baffles 26-28 so that at the exits of the flow paths 30 the refrigerant is flowing countercurrently to the direction 17 of movement of the articles 15 as indicated by the directional arrows 32. Thus the apparatus including the valves as illustrated in FIG. 1 produces a manifold effect that spreads the flow of refrigerant in the flow paths 30 across the full width of the tunnel 11 and above the fluid separating baffle 21.

The flow paths of the refrigerant to the three valves 31 in the illustrated embodiment is shown semischematically in FIG. 3. Here the liquid carbon dioxide is directed through a supply valve 32 and the flow line 33 in parallel to the three valves 31. Flow through these valves 31 causes an immediate pressure drop on the liquid carbon dioxide so that the exiting refrigerant indicated at 34 is in the form of mixed solid carbon dioxide and gaseous carbon dioxide formed both from the va porization of the liquid and the solid. The valves 31 in the illustrated embodiment are located primarily exteriorly of the chamber 11.

The structure of the valve is illustrated in FIGS. 2 and 4. As is shown there the valve comprises a tubular valve body 35 containing a longitudinally movable valve part 36 therein having on its forward end a valve closing surface 37 in the form of a truncated cone with the small end joined to the valve stem 38 and the large end adjacent the exit 39 of the valve body 35.

Surrounding the surface 37 is an annular valve seat 40 that has a sealing surface 41 that engages the closing surface 37 when the valve part 36 is in closed position as shown in FIG. 2. One of the surfaces 37 and 41 is provided with a scraping portion engaging the other surface so that when the movable part 36 is moved in opening and closing the valve solid refrigerant deposited within the valve will be scraped by the scraping portion from the other surface. In the illustrated embodiment the scraping portion is in the form of a knife edge 42 on the seat part 40 to engage the closing surface 37 of the movable part 36. The result is that when the valve part 36 is moved from its closed position as shown in FIG. 2 to its open position or to the right in FIG. 2 the scraping portion 42 scraps deposited solid carbon dioxide therefrom so that it can be carried from the interior of the tubular body 35 by the flow of refrigerant as indicated by the arrow 43 into and through the valve.

The scraping portion on the seat part 40 extends around the movable valve part surface 37 in that it has an annular shape to engage the entire circumference of the surface 37.

The valve is held in closed position as shown in FIG. 2 for movement within a bushing 44 by a helical spring 45 that is positioned around the reduced rear end 46 of the stem 38 and has one end bearing against the bushing 44 and the other end bearing against a threaded adjustable nut 47.

The movable part 36 of the valve is moved to an open position or to the right in FIG. 2 when liquid carbon dioxide is allowed to flow into the valve as shown at 43 under a pressure greater than an initial setting on the valve. That is, the valve is set at some cracking pressure by adjusting the nut 47 to compress the spring 45 to some pre-load which is transmitted to the stem 36. This pre-load is selected so that the valve will crack open at a pressure above the triple point of carbon dioxide 75 PSIA or greater.

Carbon dioxide is stored in a liquid state under a pressure of 305 PSIG and F. and will remain in a liquid state under a pressure range of 60 PSIG to 1,051 PSIG and a temperature range of 69.9F. to 87.8F. To utilize the liquid carbon dioxide as a continuously controlled fluid, that is, to control the flow rate, the valving and controls must contain the carbon dioxide within these boundaries. To accomplish this directive the shear-orifice valve was developed.

The shear-orifice valve is used in conjunction with a pneumatically operated flow control needle valve as noted in the above Wagner application and here indicated generally at 32 in FIG. 3. As the needle valve modulates the flow rate, from signals transmitted from an 1/? transducer and controller system, the shearorifice valve modulates. As the needle valve modulates the flow rate, the pressure drop across the valve varies and the shear-orifice valve senses this pressure variance and modulates.

Although the system is set up to contain the carbon dioxide within its liquid state boundaries, solid carbon dioxide still forms under conditions of low flow rate and at shut-off. It is also assumed that as the carbon dioxide exits the nozzle 48 of the shear-orifice valve (area of high velocity and low pressure), solid particulate flashes back within the seat 41 area. The shearorifice valve, with its knife edge, shears what solid matter is formed and self-cleans, keeping the valve open and free flowing.

This permits the liquid carbon dioxide to flow inwardly of a side entrance 52 to the valve body 35 and make a right angled turn to flow outwardly in the annular passage or nozzle 48 that is now formed between the surface 37 and the surface 41. Because this constitutes a rapid drop in pressure at the exit 39 of the valve the released refrigerant indicated at 32 in FIG. 1 and 34 in FIG. 3 becomes a mixed solid and gaseous carbon dioxide refrigerant with a substantially complete absence of liquid.

When the movable valve part 36 returns to the closed position of FIG. 2 solid carbon dioxide tends to be deposited on the interior of the valve body 35 and particularly in the area around the valve closing surface 37. In the ordinary valve this solid carbon dioxide would block the interior flow passage so that upon subsequent opening of the valve very little if any refrigerant would flow therethrough.

In the self-cleaning valve of the present invention because of the provision of the scraping surface illustrated at 42 the subsequent opening movement of the movable part 36 in the direction indicated by the arrow 53 would cause the scraping portion or knife edge 42 to scrape the solid refrigerant from the surface 37 so that the dislodged particles of solid refrigerant would be carried out through the exit 39 by the refrigerant which is now free to flow through the valve body.

In order that this scraped refrigerant does not itself block the fresh flow the seat part 40 of the valve is annularly arranged around the surface 37 and extends in the opposite direction to the direction of movement 53 of the movable part and provides a solid collecting annular pocket 54 between the tapered seat part 40 and the adjacent areas of the valve body 35. Then when the flow of liquid refrigerant is again started this temporarily received solid within the pocket 54 is itself carried out with the exiting refrigerant 34.

Having described my invention as related to the embodiment shown in the accompanying drawings, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the appended claims.

I claim:

1. A self-cleaning valve for a liquid refrigerant that also exists as a solid, comprising: a valve body having an inlet and an outlet for flow of said refrigerant therethrough in a downstream direction; a valve movable part in said body mounted for movement along a longitudinal axis and having an annularly tapered substantially rigid valve opening and closing surface; and an annular valve seat part having a substantially rigid seal surface for sealingly engaging said rigid tapered closing surface, said movable part moving in said downstream direction to open the valve and modulate refrigerant flow therethrough, said valve seat rigid seal surface comprising a scraping portion for engaging the tapered surface of said movable part, said scraping portion converging in an upstream direction toward said axis whereby the opening and closing movements of the movable part result in the scraping portion scraping solid refrigerant from that portion of the movable valve surface disposed upstream from the area of sealing engagement in the valve closed position.

2. The valve of claim 1 wherein said scraping portion is annularly coaxial with and engages said tapered surface only when the valve is closed.