US2292617A - Apparatus for pumping volatile liquids - Google Patents

Description

Aug. 11, 1942. L. l. DANA APPARATUS ron PUMPING VOLATILE uquxns Filed June 15, 1940 [WM QRNEYS w o W T a MA J m 4 6 a a a a 1 L3,. g 1&5 W I III]! IIIIIHHIIIIHI I M Q a I a! I 2 3% N0. m

Patented Aug. 11, 1942 UNITED STATES PATENT OFFICE APPARATUS FOR PUMPING VOLATI-LE LIQUIDS Leo 1. Dana, Buflalo, N. Y., assignor to The Linde y, New York, N. Y., a cor-..

Air Products Compan notation of Ohio Application June 15, 1940, Serial No. 340,672

7 Claims.

This invention relates to apparatus for pumping volatile liquids and particularly to plunger pumps adapted for pumping liquefied gases which have boiling point temperatures materially below 273 K. at atmospheric pressure, suchas liquid oxygen, against relatively high heads of pressure,

for example, against a head of pressure-of:fromqfl 1000 to 2000 lbs. per square .inch gaug'ei;

The invention has for its object generally the provision of an improved construction an'd larrangement of parts for pumps of thej character indicated for achieving expeditiouslyisboth;the exclusion of and convectioneaway of heat fromthe liquid being pumped.

I More specifically, the invention has forl its 'objest an improved construction for plunger pumps which are arranged for pumping highly volatile liquefied gases, such as liquid oxygen, and-which employ counter-movement of liquidand plunger The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts, which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawing,.in which:

The figure is a view, mainly in section, showing a plunger pump for pumping liquid oxygen, -arranged in accordance with the invention. I

Referring now to the drawing, a vertically arranged cylinder assembly is shown comprising a cylindrical element 10 formed with a pump chamber to receive liquid and having a relatively thick wall. The cylinder I0 is attached at the upper end to a second element ll arranged to close one end of the pump chamber, and has a third element i2 superposed and attached and serving as a packing sleeve. The sleeve element I2 is preferably mounted at its top in a plate element l3 that may be a component of frame or fcylinder lfl. The 'hlock-;I4..thus closes the lower end of the pump chamber and forms a suitable head for the. cylinder in which a plunger I5 is assembly (the showing of such frame or casing being omitted from the drawing in the interests of clearness of illustration). The elements I0, I |,.and:| 2, while they-maybe integral, are preferably separable, 'the'attachment to one another .being achieved, in any convenient manner, for example, -by..threaded joints,'as shown.

The cylinder assembly is completed by means oftIablock-like element .14 that is shown as threadedly' attached; to ;;the' lower end of the reciprocated.

The block .l4l is preferably counterbored, as shown at IE, to provideja liquid receiving space and has'a supply connection I! that communicates with the receiving space l6 through a channel I8; the latter being bored in the block I4 and formed with an offset portion having a valve seat on which a valve element I9 seats. The

valve element is arranged to open in response to the incoming stream of liquid and is therefore biased to closed position. Any convenient arrangement for this purpose may be employed, for example, a gravity seating arrangement, as shown. Access to the valve chamber in the block I4 is provided in any convenient manner, for example, by means of a removable plug IS. The extent to which'the block H is counterbored at It need only be such as to provide sufflcient space beneath the plunger to collectsolid bodies to a displaced outlet connection 2|, which comcasing that affords rigid support to the pump 55 In order that liquid may be displaced from the I pump chamber by the counter-movement of liquid and plunger, a clearance space in the pump cylinder ill at the sides of the plunger is '1 also provided, whereby liquid may flow upwardly when the plunger moves downwardly. This latter clearance space is shown at 20 and leads municates at the upper end with the clearance space 20 through a lateral bore in the element ll. Connection 2| leads-to and communicates with another valve chamber in a housing element 22 thatlhas a valve 23 seating therein. A discharge connection is provided at 24 which communicates with the passage in the valve housing at a point beyond the'valve seat. Access to the outlet valve chamber is provided through the removable plug 23'.

Here the element H is preferably counterbored interiorly to a point considerably beyond the threads which engage an end of a the element i0, and into this counterbored portion is fitted a bushing 25 of a material which both excludes heat and lubricates the plunger. The material preferred for this purpose is bonded graphite. The clearance of the bushing about the plunger is made relatively small and preferably not over .001 inch for plungers of the order of one inch in diameter. The lower end of the graphite bushing is preferably held in place by means of a spacing collar 26 which is of metal, clears the plunger, and is made to rest in a counterbored recess of slightly greater diameter than that employed for the bushing 25. The length of bushing 25 is at least equal to or greater than the stroke of the plunger.

The lower end of the graphite bushing is seen to be flush with the upper end of the enlarged portion of the deep cylindrical recess in block H, the recess being preferably shaped or counterbored to receive the spacing collar 20 which is adapted to hold the bushing in place against any tendency to downward displacement. The collar 26 is also preferably bored through radially at a point communicating with the connection 2! in order to afford a suitable exit for the liquid displaced from the pump chamber. Between the collar 26 and the cylinder ID, a sealing washer 26' is also preferably inserted.

The sleeve i2, at its lower end, has a gland lladapted to engage the threaded nipple of element ll, while the upper end of the sleeve is closed by a gland or follower 21 that preferably has an exterior shoulder or collar adapted to be engaged by a nut 2 8, which is arranged to be in screw-threaded engagement with the exterior of the sleeve. The gland or follower is arranged to press down upon a plurality of packing rings 29, which are shown as filling the space in the packing sleeve between its inner wall and the plunger l5. These packing rings are preferably of a special construction and when liquid oxygen is being pumped are of a composition avoiding the use of a. hydrocarbon or other substance that may react with' the liquid oxygen. A preferred form of packing ring for such service comprises a washer-like body of suitable inert compressed material, such as shredded asbestos, incorporating an inert solid lubricant in comminuted-form,

to a walking beam (omitted from the drawingin the interests of clearness of illustration).

In order to provide a thermal shield for the pump chamber in accordance with the invention, which will absorb heat in the liquid discharged and operate to prevent heat from entering the pump in a manner which could cause so-called "vapor binding on the suction stroke, the element II is provided with a cooling jacket comprising passage 3i, which advantageously may have the form of a helical conduit having its lower end connected at 32 to the connection 24 and its upper end leading to a receiving device. The cooling passage preferably has an extension portion 33 connected to the outlet of the helical conduit and arranged to jacket a portion of the sleeve l2. An outlet connection for this portion is provided, as shown at 34. The arrangement shown permits the countercurrent circulation of the liquid leaving the pmnp chamber in a passage which receives the liquid just discharged at its coldest end and provides for its exit at the warmer end so that a relatively uniform temperature gradient along the cooling passage is provided and contributes to the eillciency of the transfer of heat from the parts of the pump'to the outgoing liquid which may be conveyed to a vaporizer or other desired receiving device.

In operation, it is seen that the pump employs the counter-movement of liquid and plunger in eifecting the displacement of liquid from the pump chamber. Such displaced liquid is forced out through the connection 2|, thence past the valve 23 and through the conduit 24 into the passages Il-Jl and thence discharged through the conduit 34. While the liquid is traversing the passages Il-JI, it absorbs heat from the metal parts and from the packing sleeve l2. Such heat cannot enter the liquid in the pump chamber and interference with pumping operation is avoided.

The method and arrangement of connections for operating the pump above described are disclosed and claimed in copending application, Seerial No, 340,848, filed June 15, 1940 in the name of 0. A. Hansen. Other features shown herein but not claimed are disclosed and claimed in copending application, Serial No. 340,849, flied June 15, 1940, in the name of 0. A. Hansen.

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanyin drawing shall be interpreted as illustrative and not in a limiting sense,

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In apparatus for pumping a volatile liquid having a boiling point temperature materially below 273 K. at atmospheric pressure comprising the combination with a source of such liquid under a relatively low pressure, of a pump assembly comprising a cylinder formed with a pump chamber and having an inlet provided with a valve and connecting the suction end to said source, a plunger adapted to reciprocate in said cylinder and spaced from the inner wall thereof and providing thereby an appreciable clearance space therein, a discharge connection having a valve communicating with said clearance space, a closure for the other end of said pump chamber formed with an opening for passing said plunger and having packing means associated therewith for sealing the passage of said plunger, and a thermal shield comprising a helical conduit connected to said discharge and having an outlet, said shield being associated with said closure and disposed concentrically about said pump assembly in the region of plunger entry into said pump chamber and arranged to be in heat conducting relation with the parts traversed by said plunger.

2. In apparatus for pumping a volatile liquid having a boiling point temperature materially below 273 K. at atmospheric pressure comprising the combination with a source of such liquid under a relatively low pressure, of a pump assembly comprising a cylinder formed with a pump chamber and having an inlet providedwith a valve and connecting the suction end to said source, a plunger adapted to reciprocate in said cylinder and spaced from the inner wall thereof and providing thereby an appreciable clearance shield being associated with said closure and disposed concentrically with said pump assembly in.the region of plunger entry into said pump chamber and arranged to be in heat conducting relation with the metal parts traversed by said plunger.

3. In apparatus for pumping a volatile liquid having .a boiling point temperature materially below 273 K. at atmospheric pressure comprising the combination with a source of such liquid under a relatively low pressure, of a pump assembly comprising a cylinder formed with a pump chamber and having an inlet provided with a valve and connecting the suction end to said source, a plunger adapted to reciprocate in said cylinder and spaced from the inner wall thereof and providing thereby an appreciable clearance space therein, a discharge connection having a valve communicating with said clearance space at a point remote from said suction end, a closure for the other end of said pump chamber formed with an opening for passing said plunger and having packing means associwith said discharge and is disposed in said closure and coiled about said guiding bushing. the second portion communicating with said first portion and being coiled about the upper portion of said closure adjacent packing disposed therein, said helical conduit being provided with an outlet completing said second portion.

4. In apparatus for pumping a volatile liquid having a boiling point temperature materially below 273 K. at atmospheric pressure comprising the combination with a source of such liquid under a relatively low pressure, of a pump assembly comprising a cylinder formed with a pump chamber and having an inlet provided with a valve and connecting the suction end to said source, a plunger adapted to reciprocate in said cylinder, a discharge connection having a valve communicating with said cylinder, a closure for the other end of said pump chamber formed with an opening for passing said plunger and having packing means associated therewith for sealing the passage of said plunger, a guiding bushing for said plunger disposed in said closure on the pump chamber side, and a thermal shield comprising a helical -conduit connected with said discharge and having an outlet, said shield being associated with said closure and disposed concentrically with said pump assembly in the region of plunger entry into said pump chamber and arranged to be in heat conducting relation with the metal parts traversed by said plunger.

5. In apparatus for pumping a volatile liquid having a boiling point temperature materially below 273 K. at, atmospheric pressure comprising the combination with a source of such liquid under a relatively low pressure, of a pump assembly comprising a cylinder formed with a pump chamber and having an inlet provided with a valve and connecting the suction end to said source, a plunger adapted to reciprocate in said cylinder, a discharge connection having a valve communicating with said cylinder, a closure for the other end of said pump chamber formed with an opening for passing said plunger, plunger packing and guiding means in said opening having associated therewith a solid lubricant substantially inert to oxygen, and a thermal shield comprising a helical conduit connected with said discharge and having an outlet, said shield being associated with said closure and disposed concentrically with said pump assembly in the region of plunger entry into said pump chamber and arranged to be in heat conducting relation with the metal parts traversed by said plunger.

6. In apparatus for pumping a volatile liquid 1 having a boiling point temperature materially below 273 K. at atmospheric pressure comprising the combination with a source of such liquid under a relatively low pressure, of a pump assembly comprising a cylinder formed with a pump-chamber and having an inlet provided with a valve and connecting the suction end to said source, a plunger adapted to reciprocate in said cylinder, a discharge connection having a valve communicating with said cylinder, a closure for the other end of said pump chamber formed with an opening for passing said plunger and having packing means associated therewith for sealing the passage of said plunger, and a thermal shield comprising a helical conduit connected with said discharge and having an outlet, said shield being associated with said closure and disposed concentrically with said pump assembly in the region of plunger entry into said pump chamber and arranged to be in heat conducting relation with the metal parts traversed by said plunger. 7. In apparatus for pumping a volatile liquid having a boiling point temperature materially below 273 K. atatmospheric pressure, comprising the combination with a source of such liquid under a relatively low pressure, of a pump assembly comprising a cylinder formed with a pump chamber and having an inlet provided with a valve and connecting the suction end to said source, a plunger adapted to reciprocate in said cylinder, a closure for the other end of said pump chamber formed with an opening for said plunger, plunger packing and guiding means in said opening having associated therewith a solid lubricant substantially inert to oxygen, and a thermal shield associated with said closure, comprising a liquid channel in communication with said discharge and having an outlet and disposed to envelop the region of plunger entry into said pump chamber and arranged to be in heat conducting association with said plunger and closure whereby the liquid discharged absorbs heat from the pump and plunger.

LEO I. DANA.

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