Fluidized Material Pump

Abstract

A pump for pumping fluidized pulverulent material such as clay or barite from a point of supply to a point of discharge, the pump undergoing a cycle comprising a filling cycle and a discharge cycle, the cycling being self-automated, being actuated by pneumatic controls and control valves solely by the air used for pressurizing the entire device. The changeover from the filling portion of the cycle to the discharge portion of the cycle and thence back to the filling portion of the cycle when the discharge portion has been completed, and so on repeatedly, is self-regulated by the device itself, so that no other source of power such as electricity is needed. The rate at which the pump cycles may be regulated by the operator, this regulation involving again a strictly pneumatic control.

Description

This invention relates to devices for the pumping of fluidized pulverulent material, and more particularly to a pump for this purpose operated entirely by air pressure.

In recent decades, advantage has been taken of the fact that pulverulent materials generally, such as clays, silica flour, catalysts in finely divided form, barite, and the like, behave in many respects like liquids if a mass of the powdered material is maintained in a so-called aerated or fluidized state, which is generally accomplished by passing air upwardly through the mass of material from a plenum below the mass of powdered material. The material may rest on a porous membrane, which may simply be canvas or the like, this structure together with means for providing pressurized air immediately below it often being referred to as an air pad.

In many fields of application, it is convenient to store powdered material for use, particularly intermittent use, in a tank from which it may be pumped from time to time as may be needed to a point of use. A particular instance is the employment of tanks at the locale of wells being drilled for oil and gas by the rotary method, where it becomes necessary from time to time to add powdered material, such as bentonite, other clays, barite, ground limestone, and the like to the circulating fluid used in the drilling. A similar requirement arises in many diverse fields in connection with the employment of Portland cement, where a supply is provided in a suitable tank at the point of use.

Various devices have been used and proposed for pumping powdered materials in the fashion described. One type involves the use of a chamber which is filled with the fluidized material and then emptied, this cycle being repeated as long as desired. This is generally accomplished by a more or less complicated control mechanism, nearly always operated by electromagnetic devices, in which the filling of the chamber is sensed by any of several means, which then operates electromagnetic or electronic controls in such a fashion as to cycle the apparatus. Such devices require an air supply and a reliable source of electrical power. Difficulties are often encountered from relay contacts, solenoid actuators, and the like failing to operate properly, since a completely dust-free operation is seldom attainable from the very nature of the materials pumped.

An object of the present invention is to provide a self-contained air pump of the type described which is operated solely by air pressure and which is characterized by high capacity and reliable operation over long periods of use.

Another object of the invention is to provide a pump of the type described which even with a high capacity may yet be constructed in a form light enough to be readily transported from one location to another, by virtue of the relative mechanical simplicity of the assembly.

Other objects of the invention will appear as the description thereof proceeds.

In the drawings:

FIG. 1 is a general view showing the inventive device connected to a source of material.

FIG. 2 is a top view of the pump.

FIG. 3 is a cross sectional view of the pump, taken as shown by the arrows on FIG. 2.

FIG. 4 is a fluid circuit diagram of the device, and shows two of the valve mechanisms in detail, as vertical sections.

Generally speaking, and in accordance with an illustrative embodiment of my invention, I provide a chamber for receiving and discharging the pulverulent material, the chamber having an air pad in the bottom. The chamber has an inlet means for receiving the powdered material, for example from a supply tank and most desirably from gravity flow therefrom. This inlet has a check valve so that the material can flow freely into the chamber, but is prevented from flowing in the opposite direction, so that egress of such material from the chamber is prevented thereby through the inlet. The chamber also has an outlet means communicating from the vicinity of the air pad means to the exterior of the chamber. I provide an air supply, which has a number of cooperative functions in the inventive assembly. Before proceeding with a general discussion of the inventive device, the drawings will now be referred to.

In FIG. 1, the pump assembly is shown as 9, a principal feature of which is the chamber 10, which may conveniently be a generally cylindrical tank, preferably of aluminum, constructed so as to withstand a working pressure of the order of 15 to 20 pounds per square inch, and naturally a test pressure somewhat higher than this figure. The upper part of the chamber 10 bears a feed inlet 18, shown in FIGS. 1, 2, and 3, which in FIG. 1 is shown in a typical connection to a supply tank 11 containing a supply of the powdered material to be pumped, and fluidized in the supply tank 11 by an air pad 13 as a conventional fitting. The feed connection 12 may be a large diameter flexible hose.

The feed inlet 18 bears a check valve 19, which may be of a simple diaphragm type as shown in FIG. 3. The lower part of the chamber 10 bears an air pad 20, arranged as a false bottom, as shown in FIG. 3, so as to provide an air plenum 21. Passage of powdered material into the plenum 21 is prevented by the covering 22 of the air pad, which may be canvas, fiberglass, cloth, or stainless steel filter cloth, or the like, having sufficient permeability to permit the passage of air into the chamber proper. A discharge outlet 16 in the form of a pipe of large diameter in elbow shape as shown in FIG. 3 is welded to the side of the chamber 10, and communicates with the chamber in the vicinity of the air pad, as shown. Exteriorly, the discharge outlet may be connected to a discharge hose 17, as shown, which is led to the point at which the discharged material is to be used or otherwise pumped. In the filling of the chamber with powdered material, as will be described in more detail below, air is naturally displaced from the chamber, and an exit for this displaced air is provided by vent pipe 23 which is concentric with vent cap 24. The displaced air from the top of the chamber passes into vent cap 24 and then downwardly through vent pipe 23 and out discharge 16, as shown in FIGS. 1 and 4. This air can gain access to vent pipe 23 only when control chamber 45 is not pressurized, so that flexible diaphragm 25 is not pressed down against the top of vent pipe 23.

Turning now to FIG. 4, this shows main valve 27 and control valve 28. Each of these valves has essentially two positions, one being assumed during the chamber filling part of the pumping cycle, and the other being assumed during the chamber emptying part of the pumping cycle. FIG. 4 shows these two valves in the chamber emptying position.

As will be seen from the drawings, the air supply, furnished through an air hose 15 to main air inlet 29 in the bottom of main valve 27 furnishes a supply of air under pressure, for which 15 pounds per square inch gauge is suitable and preferred, to several points in the inventive assembly. With the main valve in open position as shown in FIG. 4, air is passed to plenum 21 through supply hose 30. Also, with main valve 27 in the open position, air pressure is supplied via vent hose 26 to vent cap 24. Thus, the chamber is pressurized from below, the powdered material therein is fluidized, and is caused to exit through discharge outlet 16. Check valve 19 prevents any upward flow of the material through feed inlet 18. Also, air cannot escape through vent pipe 23 because the pressure-operated closure in vent cap 24 as already described is closed.

Referring to control valve 28, which in FIG. 4 is in the discharge position as already noted, it will be seen that the valve portion 31 thereof is in such a position that air from main inlet 29 and inlet pipe 32 is blocked, so that air pressure is not supplied via conduit 33 to diaphragm 34 of main valve 27. Accordingly, this permits the pressure of the air in 29 to raise control valve 27 into the position shown.

During the discharge portion of the cycle as has been described, it will be clear that some resistance to flow is furnished by the material exiting through discharge outlet 16 during the major part of the discharge portion of the cycle. This flow restriction causes the pressure in inlet 29 and consequently in control conduit 35 to be relatively high. This has the effect of admitting air under substantial pressure through orifice 42 to diaphragm chamber 36 of control valve 28, thus raising diaphragm 37 upwardly against the pressure of spring 38, which may be adjusted by screw 39. This maintains push rod 40 in the elevated position shown in FIG. 4, and which consequently actuates toggle lever 41 so as to maintain valve portion 31 in the position shown in FIG. 4.

However, when all of the material in the chamber has been discharged therefrom by the action described, then the air supplied to plenum 21 meets little resistance in exiting from the chamber. This causes a pressure drop at 29, and consequently a pressure drop in control conduit 35, so that spring 38, being properly adjusted, forces control diaphragm 37 downwardly and pushes the air in diaphragm chamber 36 out and eventually into 29. When this happens, push rod 40 is pushed downwardly by the force of spring 38, so that toggle lever 41 is moved into the alternate position from that shown in FIG. 4, which has the effect of admitting air from inlet pipe 32 to conduit 33, whence it flows into main valve 27, exerting pressure against diaphragm 34, and closing the main valve. When the main valve is thus closed, it is clear that control chamber 45 in vent cap 24 is no longer supplied with air pressure through vent control line 26, and moreover, air is no longer supplied to plenum 21, the main valve being closed. Accordingly, a fresh supply of aerated pulverulent material is free to fall downwardly through check valve 19 and feed inlet 18 into chamber 10. A relief valve 46 prevents any build-up in pressure above the selected operating pressure, e.g., 15 pounds per square inch. While this filling action is taking place, however, with main valve 27 closed, full air pressure is once more supplied to diaphragm chamber 36 through control conduit 35, restricted, however, by adjustable orifice 42. This orifice is adjusted so that for the particular powdered material being supplied to the chamber, by the time the chamber is approximately full, enough air will have traversed orifice 42 and entered diaphragm chamber 36 so as once more to overcome the force of spring 38 and to raise diaphragm 37, thus raising push rod 40 once again into the position shown in FIG. 4. This initiates a new discharge cycle, which takes place precisely as has been described before. The cycles of filling and discharging continue indefinitely, at the will of the operator.

It will be seen, in accordance with the foregoing description, that as the pumping continues through a full cycle of filling and discharging, air passes in and out of diaphragm chamber 36, first in one direction and then in the other, in response to the pressure differential between chamber 36 and air inlet 29, this differential being first in one direction and then in the other. However, the rate of this ebb and flow of air in and out of chamber 36 may be controlled by adjusting orifice 42, as already noted. Over and above the regulating action of this orifice, however, the pressure differential switches over from the discharge part of the cycle to the filling part of the cycle essentially as a result of the actual duration of the discharging operation, so that the inventive pump assembly is remarkably self-automated, particularly considering that the sole source of energy is air pressure, which serves not only to effect the pumping action, but to operate the various controls so as to cycle the device and all in accordance with ambient conditions. For example, depending upon length of the discharge hose 17 in a given application, and the density and fluidized flow properties of the material to be discharged, the discharge portion of the cycle will vary in duration from one instance to another. Yet, as will be clear from the foregoing description, the variance of the duration of the discharge is automatically taken care of by the pneumatic actions described. Likewise, as has been explained, the opening and closing of the vent is automatically controlled by the cycling operation itself.

The materials of construction call for no special comment, being conventional in the art. Thus, the housings and operating portions of the valve mechanisms may be of aluminum or brass, or the like. The diaphragms may be of synthetic rubber such as neoprene, and the spring elements of steel, phosphor bronze, or beryllium copper. In a preferred embodiment, the outside diameter of the cylindrical chamber 10 is 24 inches, with the dimensions being to scale as shown in FIGS. 1, 2, and 3.

In practice, the filling cycle is typically from two to three seconds, while the pumping cycle is from two to three times this duration, viz., from about four to nine seconds, so that something of the order of six to eight complete cycles per minute take place.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

Claims

Having described the invention, I claim:

1. A pump for fluidized pulverulent material comprising in combination;

an air supply;

chamber means for receiving and discharging said material;

one-way entry means for ingress of material into said chamber; discharge outlet means for said material;

aeration means in said chamber for fluidizing and expelling said material from said chamber;

vent means for venting air from said chamber while said chamber is receiving material;

vent closure means for said vent operatively connected with said chamber and responding to air pressure within said chamber so as to permit said vent to open while said chamber is receiving material and causing said vent to close while material is being discharged from said chamber;

main valve control means actuated by resistance to air flow in said aeration means resulting from said chamber containing said material and under such conditions supplying air to said aeration means, said valve means operating to close said aeration means air supply when said chamber has discharged said material;

three-way control valve means operatively connected with said air supply and comprising a control air chamber, said control air chamber receiving air from said air supply through an adjustable orifice when said transient air supply pressure is greater than the pressure in said control chamber and discharging said air through said adjustable orifice when the air pressure in said control chamber is greater than said transient air pressure;

said three-way control valve supplying air to said main valve so as to close said main valve so as to create a material-filling condition in said chamber means and operating to release air from said main valve as a consequence of build-up of pressure within said three-way valve control chamber so as to open said main valve and thereby create a material-discharge condition in said chamber means.

2. A pump for fluidized pulverulent material comprising, in combination:

chamber means for receiving and discharging material;

air pad means in the bottom of said chamber;

material inlet means discharging into the upper part of said chamber;

check valve means in said inlet means preventing egress of material from said chamber;

discharge outlet means leading from the vicinity of said air pad means to exterior of said chamber;

vent cap means communicating with said chamber means;

vent pipe means communicating from said vent cap to outside of said chamber;

air pressure diaphragm closure means releaseably closing said communication between said vent cap and said vent pipe means;

air supply means;

relief valve means;

main air valve means comprising a diaphragm means an receiving air from said air supply means and discharging said air through a releaseable closure means operatively connected with said diaphragm means to said relief valve and to said vent communication closure diaphragm means and to said air pad means;

a three-way control valve means having a bistable toggle action and supplied with air from said air supply means, in a first position permitting air to flow to diaphragm means on said main air valve so as to close said releaseable closure, and in a second position closing off said air supply but venting said main air valve diaphragm to atmosphere so as to permit said releaseable closure to open;

control valve actuating diaphragm means comprising an air control chamber, spring means, and actuating rod to said bistable toggle means, so that when said control chamber is pressurized with air, said control diaphragm is forced against said spring means so as to move said actuating rod so as to move said toggle action to said second position, and so that when said control chamber is not pressurized, said spring means forces said actuating rod so as to move said toggle means into said first position and to force said air out of said control chamber; and

adjustable orifice means interposed between said air supply means and said control chamber, so that the rate of ingress and egress of air from said control chamber may be regulated.