US3773230A

US3773230A - Discharge of containers and pressure vessels

Info

Publication number: US3773230A
Application number: US00204209A
Authority: US
Inventors: R Murfitt
Original assignee: Rowan Investments Ltd
Current assignee: Rowan Investments Ltd
Priority date: 1970-11-18
Filing date: 1971-12-02
Publication date: 1973-11-20
Anticipated expiration: 1990-11-20
Also published as: DE2215524A1; GB1353158A

Abstract

To facilitate removal of pourable substances such as powdered or granular material and liquids from closed storage and/or transporting containers, pressurised air is fed through a common air inlet system into the container and into an outlet conduit extending from the comtainer. To avoid blockage in the outlet conduit, a shroud is provided over each air inlet to the chamber to direct the air transversely of the outlet of the container to form an air curtain across the outlet, and the branches of the common air inlet system which are connected to the air inlets and the outlets of the container are provided with flow regulating means which ensure that air is fed to the outlet conduit whenever pressure in the air inlet system rises above a predetermined value as a result of back pressure in the container.

Description

United States Patent Murfitt [75] Inventor: lliglpllgulillurfitt, W1sbech, Cambs, Assistant Examiner joseph J. Rona g AttorneyWoodhams, Blanchard & Flynn [73] Assignee: Rowan Investments Ltd., Douglas,

Isle of Man, United Kingdom 57 ABSTRACT [22] Filed: Dec. 2, 1971 To facilitate removal of pourable substances such as powdered or granular material and liquids from closed [2!] Appl 204209 storage and/or transporting containers, pressurised air is fed through a common air inlet system into the con- [30] F i A li i priority Data tainer and into an outlet conduit extending from the Nov. 18 1970 Great Britain 54 915 70 icohtaiher- To [avoid blockage in the P i conduit 3 shroud is provided overefi afi ihlet to the chamher 52 US. Cl. 222/193 302/57 direct the air transversely whet 51 Int. Cl B6711 5/54 mine ah ah cumin the much and the 58 Field of Search 222 153 195 556- branches f the ah System which we 302/53 251/343 3 connected to the air inlets and the outlets of the container are provided with flow regulating means which [56] References Cited ensure that air is fed to the outlet conduit whenever pressure in the air inlet system rises above a predeter- UNITED STATES PATENTS mined value as a result of back pressure in the con- 2,792,262 /1957 Hathom 222/ 195 UX tainen 3,213,884 /1965 Moyer et a1. 251/343 X 3,305,150 2/1967 Campbell et 222/193 X 3,404,699 10/1968 Arons 137/541 X Claims, 5 Drawing Figures 2,723,054 11/1955 Louden et 222/195 2,738,615 3/1956 Childs et al 222/193 DISCHARGE OF CONTAINERS AND PRESSURE VESSELS 949,053 2/1910 Baron 222/556 Primary Examiner-Samuel F. Coleman PATENTEDNUV 20 1975 SHEET LEE 3 DISCHARGE OF CONTAINERS AND PRESSURE VESSELS The invention relates to pneumatic discharge means for removing pourable substances such as powdered or granular materials and liquids from closed storage and- /or transporting containers which can be pressurised.

It is well known that to discharge powdered or granular material from closed containers one may aerate the material so it is fluidised and will flow at the point of discharge when the material is stacked at an angle greater than the angle of repose and would otherwise fall by gravity.

An object of the present invention is to provide discharge means for a closed container which does not include an aeration pad or fluidising valve, and can be readily used for liquids, granular material or powders.

According to the invention there is provided pneumatic discharge means for removing pourable substances from a closed storage and/or transporting container having at least one air inlet opening and an outlet opening fitted with a discharge valve, the discharge means comprising an air inlet system having an inlet branch for the supply of air at or above a first pressure through the inlet opening in the container and a booster branch including a pressure responsive valve which is set to open when the pressure in the inlet system exceeds the first pressure by a predetermined margin to allow passage of air into a discharge line extending from the discharge valve, and a shroud fitted over the inlet opening to deflect inlet air transversely across the outlet opening of the container.

Some embodiments of the invention are hereinafter described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional elevation of pneumatic discharge means fitted to one end of a closed storage container for particulate material;

FIG. 2 is an end view of part of the discharge means shown in FIG. 1, when viewed in the direction of Arrow FIG. 3 is an end view of alternative discharge means to those shown in FIGS. 1 and 2;

FIG. 4 is a sectional elevation of a third form of discharge means fitted to the bottom end of a closed storage container; and

FIG. 5 is a sectional elevation of a preferred form of sleeve valve suitable for use in the pneumatic discharge means described with reference to FIGS. 1 to 4.

As shown in FIG. 1, air is piped into a closed container 17 through an air supply line 7 and an air supply system comprising pipework 6. Fitted into inlet and booster branches of the pipework 6 are two poppet valve closure members 1 and 3.

The poppet valve closure member 1 of FIG. 1 is set to release at a pressure of 1 PSI. n release, the air enters the container 17 through an annular chamber 9 which allows the air to pass the poppet valve when the closure member 1 is under pressure, the air then enters the container 17 through an inlet in an end plate 18 of the container 17. A shroud 2 is fitted over this inlet 5 to deflect the inlet air transversely across the outlet opening 10.

The size of the shroud 2 depends on the size of the container 17 and the inlet 5, and the nature of the material to be discharged from the container 17, and a 300 cubic feet container which is to carry cement powder,

may have an inlet of 1% sq. ins. to 10 sq. ins. according to the rate of flow of the air and the nature of the material (cement powder has a number of different consistencies and variations in chemical composition).

It is also preferable that the distance between the outlet of the shroud 2 and the outlet 10 of the container 17 is not more than 36 inches.

Once the pressure within the container 17 is at the required level and the discharge line 14 of the container 17 has been connected to a storage silo, a discharge valve 4 which is fitted to the outlet 10 of the container and has a closure member 11 is opened, and material and air then flows through a discharge line 14 from the container 17. When the pressure in the container 17 increases and the pressure in the pipework 6 rises to a second release pressure, greater than 1 PSI, poppet valve closure member 3 opens and air from pipework 6 boosts the discharge through line 14. When the pressure in the pipework 6 falls below the second release pressure, poppet valve closure member 3 closes. In practice, for inlet flows of between and 1,000 CMF (cubic feet per minute) the second release pressure is between 5 and 40 PSI, and may even be as low as 3 PSI.

Fitted within the discharge line 14, adjacent the outlet of the discharge valve 4, is a tubular member 13 which extends beyond the connection between the booster branch of the pipework 6 and the discharge line 14.

The cross-sectional area of the radial space between the sleeve 13 and the outer wall of the discharge line 14 preferably equals the cross-sectional area of the booster branch of the pipework 6, but this can vary according to the materials and air supply used.

Because air enters container 17 through an inlet 5 which has a shroud 2, the air enters at a particular rate of flow, at a particular pressure, and at a particular velocity, and the air flow is such that it not only acts as an aeration or fluidising medium but also creates an air control curtain over discharge outlet 10 of the container. Thus the air flow acts not only to cause discharge of particulate material from the container 17 but also controls the rate of discharge so that lower rates of air flow and pressure are suflicient.

By means of this construction inlet air is directed so as to form an air curtain or screen which, when the pressures within the container 17 are equal or less than those in the discharge line 14 and the pressures in the shroud 2 equal or exceed those in the adjacent areas, retard the rate of discharge through the outlet 10.

As there are no conventional aearation pads or valves within the container 17, the container can be used for fluids and for dry material. Alternating use is possible by either having a bag arrangement within the tank or by cleaning the tank out.

As shown in FIG. 3, the end plate 18 of the arrangement illustrated in FIG. 1 may be replaced by a detachable hinged plate 20 supported on hinges 16.

In the embodiment of the invention illustrated in FIG. 4, the discharge means includes a shroud 2 fitted over an air inlet 5 formed in the conical bottom end of a container 17 for particulate material. Pipework 6 providing an inlet air system with inlet and booster branches connects air supply line 7 to the air inlet 5 and the discharge line 14, through two poppet valves having closure members 1 and 3. The discharge line 14 is formed as an elbow which has a vertical inlet leg, ex-

tending from a, discharge valve 4 fitted to the outlet of the container and having a closure member 11, and a horizontal outlet leg aligned with the booster branch of the pipework 6 containing the poppet valve closure member 3. I

The shroud 2 directs inlet air downwards so as to fluidise particulate material in the container and to form an air curtain or screen over the outlet 10 to the container 17. Thus, even when the discharge valve 4 is opened, discharge is impeded until the air pressure inside the container 17 increases and the pressure in the pipework 6 rises to the value at which the closure member 3 opens to allow boost air to enter the discharge line 14 and so assist the discharge. To assist in fluidising particulate material within the container 17, the shroud 2 may include a plate which is formed with perforations.

Although the discharge means described with reference to the drawings include air inlet systems having only two branches, further inlet branches are possible. Although only one boost branch is required for the supply of boost air to the discharge line two or more branches may supply air to inlet orifices provided with shrouds for the formation of air curtains over the container outlet.

As a further modification of the construction described above, each shroud may include a perforated plate which acts as a fluidising bed.

Although flow regulation in the inlet and booster branches of the pipework 6 is provided by poppet valves, this regulation may be provided by ball valves or flap valves. Moreover, in one practical form of construction, the valve disposed in the inlet branch consists of a split butterfly valve having two spring loaded halves set to open when the pressure in the inlet system exceeds the pressure in the container by a predetermined amount.

The valve disposed in the booster branch is required to operate solely in response to the pressure in the inlet system regardless of the pressure in the discharge line, and may consist of a sleeve valve. In one practical construction of such a sleeve valve, shown in FIG. 5, the boost branch 6A of the pipework 6 extends from a manifold chamber 68 surrounding a part 6D of the pipework 6 formed with ports 6C. A piston having a skirt 21 and a central spindle 22 is movable under the pressure of air in the part 6D from a fixed seat 23 to compress a spring 24 disposed around the spindle 22 between the skirt 21 and adjustable stop means 25 attached to the end of part 6D. The spindle 22 passes through a hole formed in the stop means 25 and a gap formed between radial guides 26 provided inside the part 6D so that as the pressure in'the part 6D varies, the

skirt 21 moves axially along the part 6D to vary the opening of the parts 60. Marks 22A are provided on the exposed end of the spindle 22 to indicate when the ports 6C are fully open and fully closed.

I claim:

1. In a closed container for pourable substances, said container having at least one air inlet opening and an outlet opening fitted with a discharge valve, and pneumatic discharge means for removing said pourable substance from said container, said discharge means including a discharge line connected to and extending downstream of the discharge valve, the improvement comprising an air inlet system having an inlet branch for the supply of air at or above a first pressure through the inlet opening in the container and a booster branch connected to the discharge line and including a pressure responsive valve which is set to automatically open when the pressure in the inlet system exceeds the first pressure by a predetermined margin to allow passage of air into the discharge line, and a shroud co-operable with the inlet opening to deflect air from the associated inlet branch transversely across the outlet opening of the container.

2. Pneumatic discharge means according to claim 1, in which the pressure responsive valve is a poppet valve.

3. Pneumatic discharge means according to claim 1, in which the pressure responsive valve is a sleeve valve.

4. Pneumatic discharge means according to claim 1, in which the inlet branch includes a flow regulating device.

5. Pneumatic discharge means according to claim 4, in which the flow regulating device comprises an additional pressure responsive valve which is set to open when the pressure of the air in the inlet system rises to the first pressure.

6. Pneumatic discharge means according to claim 5, in which the additional pressure responsive valve is a poppet valve.

7. Pneumatic discharge means according to claim 1, in which the air inlet system includes at least two inlet branches.

8. Pneumatic discharge means according to claim 1, including a tubular member mounted within the discharge line adjacent the connection between the booster branch of the air inlet system and the discharge line.

9. Pneumatic discharge means according to claim 8, in which the cross-sectional area of the radial clearance space between the discharge line and the tubular member equals the cross-sectional area of the booster branch of the inlet system. I

10. Pneumatic discharge means according to claim 1, in which the discharge line is formed as an elbow and the booster branch of the inlet system extends perpendicular to the inlet leg of the elbow and in alignment with the outlet leg of the elbow.

l1. Pneumatic discharge means according to claim 1, in which the shroud includes a perforated plate which acts as a fluidising bed.

12. Pneumatic discharge means for removing pourable substances from a closed container, comprising a container wall member having at least one air inlet opening and an air outlet opening fitted with a discharge valve, a discharge line connected to the dis charge valve, an air inlet system having an inlet branch extending upstream from the inlet opening for the sup ply of air at or above a first pressure to the container and a booster branch including a pressure responsive valve which is set to automatically open when the pressure in the inlet system exceeds the first pressure by a predetermined margin to allow passage of air into the discharge line, and a shroud fitted over the inlet opening to deflect air from the associated inlet branch transversely across the outlet opening.

13. Pneumatic discharge means according to claim 12, in which the wall member is a movable closure member of the container.

14. Pneumatic discharge means according to claim 12, in which the wall member is a hingedly connectable closure member of the container.

15. Pneumatic discharge means according to claim 12, in which the wall member is inthe form of a discharge hopper.

I I I

Claims

9. Pneumatic discharge means according to claim 8, in which the cross-sectional area of the radial clearance space between the discharge line and the tubular member equals the cross-sectional area of the booster branch of the inlet system.

11. Pneumatic discharge means according to claim 1, in which the shroud includes a perforated plate which acts as a fluidising bed.

12. Pneumatic discharge means for removing pourable substances from a closed container, comprising a container wall member having at least one air inlet opening and an air outlet opening fitted with a discharge valve, a discharge line connected to the discharge valve, an air inlet system having an inlet branch extending upstream from the inlet opening for the supply of air at or above a first pressure to the container and a booster branch including a pressure responsive valve which is set to automatically open when the pressure in the inlet system exceeds the first pressure by a predetermined margin to allow passage of air into the discharge line, and a shroud fitted over the inlet opening to deflect air from the associated inlet branch transversely across the outlet opening.

15. Pneumatic discharge means according to claim 12, in which the wall member is in the form of a discharge hopper.