US2374564A - Safety device for valves - Google Patents

Description

April 1945 J. G. REID, JR., ETAL 2,374,564

SAFETY DEVICE FOR ,VALVES Filed Sept. 22, 1943 ATTORNEY Patented Apr. 24', 1945 I new smes- OFFICE 2,374,564 v SAFETY nnvrcnron vALvEs "John G. Reid, Jr,, and .vLow'ell McNeely, Evans- V ville, Ind., assignors to Servel, Inc., New York, v N.,Y., a corporation ofDelaware I g Application September 22, 1943. SerialNo. soasso g i I 'lClaims. (of. 62-119) have other uses they are particularly adapted for,

use with'absorption refrigerating systems to permit purging of non-condensible gases.

In the application referred to above the valve is shown applied to an absorption. refrigerating the type indicated which'is of'simple construe-=- system which operates in a partial vacuum and utilizes water as a refrigerant'and a saline solution asan absorbent. With such a system-noncondensible gases may accumulate which must be purged from the system. The valve through which the non-condensible gases are purged is in the form of a porous plate having a small amount of liquid, such as mercury, covering its upper surface. When the pressure on the mercury side of the plate is less than the pressure on its opposite side, gases will flow through the valve. However, when the pressure existing above the mercury on the porous plate is substantially equal to or greater than that prevailing below the plate,

the mercury is effective to close and seal the pores or openings in the plate and prevent the flow 'of gas therethrough.

A gas separating chamber is connected to the refrigerating system through the mercury valve and seal which permits the non-condensible gases to flow from the system to the chamber when the latter is evacuated but prevents the flow of air into the system from the atmosphere. The gas separating chamber may be evacuated by any suitable means but preferably an inexpensive water operated aspirator is used for this purpose. While the mercury valve and seal operates quite satisfactorily it may sometimes happen that the restricted throat of the aspirator will become clogged causing the water of the jet to flow into the gas separating chamber. Such accumulation and backing up of the water in the gas separating chamber will increase the pressure therein above that of the surrounding atmosphere which is apt to damage the valve by forcing the mercury through the porous plate.

One of the objects of the present invention is to provide a safety device for the mercury valve when the pressure therein tendsto exceed th pressur of the atmosphere. 7 v

Another object is'to provide a safety device of tion and one "which is efflcient' and positive in its operation.

These and other objects will become more apparent from the following description and drawing in which like reference characters denote like parts throughout'th several views. It is tobe expressly understood, however, that the drawing is for the purpose of illustration only and not v a definition of the limits ofthe invention, reference being had for this-purpose to the appended claims. In the drawing: a

Fig. 1 is a diagrammatical view I tion refrigerating system incorporating the novel features of the present invention; I

Fig. 2 is an enlarged detail view showing the mercury valve and separating chamber for purging gases from the refrigeration system and the relief valve in the chamber for protecting the mercury valve from excessive pressures; and

Fig. 3 isa transverse sectional view "taken on line 3-3 of Fig. 2 showing the construction of' the relief valve.

Referring to Fig. 1 of the drawing, the invention is shown as applied to a two-pressure absorption refrigerating system similar to that illustrated and described in the copending applies-- tion of Charles A. Roswell referred to above. In a' system of this type liquid refrigerant such as, for example, water is introduced into the upper part of an evaporator or cooling element i II from .a condenser H through a path of fiow including consequent absorption of heat from the ambient,

' as from a stream of air flowing over the exterior surface of thetubes l4 and fins l5 of the evaporator. The refrigerant vapor formed in evaporator i0 'fiows therefrom to absorber IS in which the vapor is absorbed into a liquid absorbent such as, for example, a solution of lithium chloride.

The absorption liquid enriched in refrigerant is conducted from the absorber 16 to a generator I? in a path of flow including a conduit I8, liquid heat exchanger I9, conduit 20, vessel 2|, and conduit 22. Within the generator l'l are disposed .a plurality of riser tubes 23 enclosed by a chamber formed by an outer shell to which steam is supplied through a conduit 24 from a suitable source of supply, The heating of the riser tubes 23 by the steam causes refrigerant vapor to be expelled from the absorbent, and such expelled vapor is of an absorpthe absorber.

effective to raise liquid absorbent by gas or vaporlift action.

The expelled vapor passes from the upper ends of the riser tubes 23 into a vapor separator 25 and thence flows through a conduit 26 to the condenser in which the vapor is liquefied. Liquid refrigerant formed in condenser I I flows through the U-shaped tube I2 to the upper part of the evaporator H), as explained above, to complete the refrigerating cycle. The raised absorption liquid from which refrigerant vapor has been expelled is conducted from the upper part of the generator H to absorber l6 to absorb refrigerant vapor, this liquid being conducted to the absorber in a path of flow including a conduit 21, liquid heat exchanger l9 and conduit 26. The heat liberated by absorption of refrigerant-vapor in absorber l 6 is taken up by the cooling medium such as, for example, water which flows upward through vertically disposed banks. of pipes 29 in The cooling water is introduced into the lower end of the banks of pipes through a conduit 36 and is discharged from the upper ends of the banks of pipes through a conduit 3|. The conduit 3! is connected to condenser H so that the cooling water may separately be utilized to effect cooling of the condenser H. Cooling water is discharged from condenser H through a conduit 32. I

The system operates in a partial vacuum with generator I! and condenser H operating at one pressure and evaporator l and absorber I 6 The pressurenon-condensible gases may accumulate in the various elements'of the system. As explained in detail in the copending application of Charles A. Roswell, referred to above, the gas from' condenser II is transferred to the evaporator l0 and the non-condensible gases in the evaporator are swept into the absorber l6 by the refrigerant as it flows into the absorber at high velocity. The non-condensible gases then accumulate in a layer at the bottom of the absorber 16. In order to transfer non-condensible gases from the absorber I6 to a vertical conduit 34 and vessel 35, which may be referred to as inactive parts of the system, an auxiliary absorber 36 is provided into which the non-condensible gases inthe bottom of the absorber are drawn through a conduit 3'1.

Absorption liquid is introduced into the auxiliary absorber 36 through a conduit 38 which is connected at its upper end to conduit 28. In this way a portion of the absorption liquid flowing to the upper part of the absorber I6 is diverted from conduit 28 into-conduit 38. The diverted absorption liquid is brought into intimate contact with the gases in the auxiliary absorber '36. Preferably a cooling coil, not shown. is provided within the auxiliary absorber 36 which is connected-between the conduits 30 and 3| of the cooling system by. means of connecting pipes 42 and 43. A vertical tube 44. which may be referred to as a fall tube pump, is connected at its upper end to the bottom part of the auxiliary absorber 36'and its lower end to the bottom part of the vertical conduit 34. Liquid intermittently fills the upper bent end of the vertical tube 44 and siphons therefrom,

- whereby small quantities of the non-condensible gases are withdrawn from the bottom part of 35 increases, the liquid level in conduit 34 falls with the gases displacing the liquid which flows from the bottom of the conduit 34 into theconduit 18 through a connection 45.

The non-condensible gases in vertical conduit 34 and vessel 35 are exhausted from the refrigeration system to the atmosphere by a suitable vacuum pump such as, for example, a simple type water operated aspirator 46. The aspirator 46 is connected by a conduit 41 to a gas separating chamber 48 which, in turn, is connected by means of a conduit 49 to vessel 35."

Conduit 41 is connected to the side of the throat of a Venturi tube forming the aspirator 46, see

Fig. 2. A nozzle orifice 50 is disposed. within the aspirator 46 and water under pressure is delivered thereto through a conduit 5!. The conduit 5| is connected to conduit for supplying cooling water to absorber l6 and in the conduit 5l is a manually operable valve 52 for controlling the operation of the aspirator.

In conduit 49 connecting the gas separating chamber 48 to the vessel is a mercury type valve 53 which is effective to maintain the refrigerating system at a low pressure and at the same time allow non-condensible gases to pass therethrough when the aspirator 46 is operated.

As shown most clearly in Fig. 2, the mercury valve 53 comprises an elongated vertical vessel across which a porous septum plate 55 extends.

A small body 56 of a liquid such as, for example, mercury covers the top surface of the porous septum plate 55. The vertical vessel of the valve 53. may be formed of non-porous glass and the plate 55 may consist of a porous body of ceramic material, fritted or sintered glass particles, or glass strands. Such porous plates 55 formed of fritted or sintered glass are described in United States Letters Patent Nos. 1,620.815, 2,115,748, and 2,136,170. As thus far described, the system of refrigeration is substantially identical withthat illustrated and described in the copending Roswell application, referred to above.

In accordance with the present invention a relief valve 66 is provided in the gas separating chamber 43 and is operated by the pressure therein to vent the chamber to the atmosphere. As shown most clearly in Fig. 2 the relief valve 66 comprises a valve body 6| in the form of a nipple attached at one end to a pipe connection 62 at the upper end of the chamber 48. The valve body 6| has an axial opening 63 communieatin with the interior of the-chamber 48 and an annular valve seat 64 at its upper end. A

bonnet 65 is attached to the valve body 6! by axialopening 88 in thevalv'e body'il. A conduit 88 connects the upper end of the bonnet 88 to a discharge tube 88 extending, from the aspiratof 48 and continues beyond the latter to provide a drain pipe Ill.

When it is desired to effect removal of. noncondensible gases from the refrigerating system.

the valve 82 is opened so that water will be supthe pressure in the chamber 48 necessary tonnseat valve plate 81 is substantially equal to or only slightly in excess or the atmospheric pressure.

plied to the nozzle 80 ofthe aspirator 48. The

water through thenozzle 88 acquires -a highvelocity and entrains' gas or liquid flowing through the conduit 41 from the gasseparating chamber 48 whereby to evacuatethe chamber and v eflect a partial vacuum on the upper or outside of the mercm'y valve 58 in communication with the chamber through the conduit 49. When the pressure on the top or outside of the mercury valve 83 is less than the pressure below or on the inside of the valve the non-condensible gases in the vessel 85 and tube 34 of the refrigerating system -will pass upward through the porous septum plate 58 and bubble through the small body of mercury 88; As the non-condensible gases are drawn through'the valve 83 they pass through.

the conduit 49 into the chamber 48 and through the conduit 41 where they are entrained with the water of the aspirator 48 and exhausted through the discharge tube 88 and drain pipe 18. This operation is continued until the liquid in the conduit 84 rises to a'predet'ermined level. when this level is reached the valve 82 is closed to discontinue the operation of the aspirator 48. The atmosphere then enters through the drain pipe Ill, discharge tube-89,- conduit 41, chamber 48 and flow of the water therethrough. Instead'of evacuating the chamber 48 the'water for the aspirator 48 then wi1l flow into the chamber and tend to create a pressure therein greater than the pressure of the atmosphere surrounding the refrigeration system, Immediately upon the occurrence of such an abnormal condition the increase in pressure in the chamber 48 will be transmitted through the axial opening 83in the valve body 8| of the relief valve 80 and unseat the valve plate 81 .to vent the interior of the chamber 48 to the atmosphere throughthe conduit 88 and drain ipe l8. Dur- -ing the normal operation'of the Dlrator 48 the It will be understood, however, that the conduit may be-made comparatively longso that the valve plate will. open at pressures below the pressure,

of the atmosphere upon the occurrenceof an abnormal condition such as the plugging of the throat of the aspirator.

It will also be apparent that the construction will provide awater seal in the conduit 88 in case of improper or faulty seating of the valve plate 81. Should the valve plate 8! fall to properly seat,the water exhausted from the aspirator' 48 through the discharge tube 89 will be drawn upwardly through the conduit 88 and fill the valve chamber 7 88. The small amount of water which might leak between the'valve'plate 61 and valve seat 84. will not materially aflect'the operation of the aspirator 48 in evacuating the chamber 48.

It will now be observed from the foregoing specification that the present invention provides a safety device for-a mercury valve and seal to prevent it from being subjected to excessive pressures.

ture which is positive. and emcient in operation.

Whilea preferred embodiment of the invention is herein shown and described as applied to a particular absorption refrigeration system, it

. will be apparent to those skilled in the art that the invention may be applied to other systems and that various modification nand changes may be made in the construction of the parts without departingfrom the spirit or scope or the invention. For instanceigthe safety. device for the mercury valve and seal may be used in other absorption refrigerating systems than that herein illustrated and described or may be applied to other kinds of systems such, for example, as vapor pressure heating system or the like. Therefore, without limiting ourselves in this respect,

1 we claim:

- i. In an absorption refrigerating system having a'valve for permitting the ,escape of gases therefrom while preventing the flow of gases thereto, the combination With'said valve of a chamber connected thereto, a jet type aspirator for evacuating the chamber, means for supplying fluid to said aspirator at a pressure above the a atmosphere surrounding the system, and a relief chamber '48 will be partially evacuated and the atmospheric pressure operating on the top of the valve plate 81 0f the relief valve 88 will'tend to engage .the plate tightly with thevalve seat 84. Any slight leakage which may occur between the valve plate 81 and valve seat 84 will tend to create a vacuum in the conduit and draw part of the water discharged from the aspirator 48 upwardly in the conduit. Such column of water inthe conunit 88 will then tightly seal the connection so as to adapt the -chamber 48 to be emciently 1 evacuated,

The increase in pressure in nece'ssary'to vent the latter will be equai'to the sum of the pressure required to liftthe valve plate 81 and the pressure drop through the valve pas.- sages83, 88 and conduit 88 less the pressure head of the column of water in the conduit. Preferably the conduit is made relatively short so that the chamber 48 f valve in said chamber for venting the latter to the atmosphere, said relief valve being normally closed by the pressure of the atmosphere and opened automatically by pressure in the chamber. I 2. In an absorption refrigerating systemhaving a valve fo 'j'p rmitting the escape of gases therefrom while preventing the how of gases thereto, the combination with said valve of a chamber connected thereto, a water operated as-'- pirator for evacuating the chamber and having a discharge tube, means for supplying water to said aspirator, a relief, valve in said chamber, and a conduit connecting said relief valve and discharge tube from the aspirator whereby any leakage through the relief valve will produce a partial vacuum in the conduit to cause the relief valve to be opened by a pressure in the chamber below the, pressure of the surrounding atmosphere.

3.' In an absorption refrigerating system a valve for purging non-condensible gases commieing a porous plate and a body of mercury covering the outside of said, plate, a chamber son'- It will also be observed that thepresent invention provides a simple and compact strucnected to said valve at the outside oi said plate, means for evacuating the chamber, and a relief valve in said chamber for venting the latter to the atmosphere.

4. In a closed system for circulating gases or vapor at a pressure below the pressure of the surrounding atmosphere, a valve for permitting the escape of gases from the system while preventing the flow of. gases thereto, said valve comprising a porous plate and a body of mercury covering the outside of said plate, means for producing a vacuum on the outside of the plate of said valve surrounding atmosphere, a valve for permitting the escape of gases from the system while preventing the flow of gases thereto, said valve comprising a porous plate and a body of mercury covering the. outside of said late, a chamber connected to the outside of the plate of said valve,

a water operated aspirator for evacuating said chamber, and a relief valve in said chamber for venting the latter to the atmosphere upon a predetermined increase of-pressure therein.

6. In an absorption refrigerating system, a gas storage vessel, a vacuum pump connected to a storage vessel, a valve between the vacuum pump and storage vessel for permitting the escape of gases from the system while preventing the flow of gases thereto, and a relief valve between the valve and vacuum pump and automatically operable to limit the pressure applied to the valve.

7. In an absorption refrigerating system, a gas storage vessel, a chamber connected to, the storage vessel, a valve between the storage vessel 1 and chamber for permitting the escape of gases from the vessel while preventing'the fiovv of gases thereto, a vacuum pump connected to evacuate the chamber, and a relief valve in said chamber for venting the latter to the atmosphere upon a predetermined increase of pressure therein.

JOHN G. REID, Ja. LOWELL MCNEELY.

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