GB2260306A

GB2260306A - A powder transfer system

Info

Publication number: GB2260306A
Application number: GB9221208A
Authority: GB
Inventors: Dennis Keith Hodder
Original assignee: Oiltools International BV
Current assignee: Oiltools International BV
Priority date: 1991-10-08
Filing date: 1992-10-08
Publication date: 1993-04-14
Also published as: GB9121433D0; GB9221208D0; NO923890L; NO923890D0

Abstract

A system is described for transferring a powder from a first location to a second location. The system includes a hopper (10) for storing the powder, a conduit (20) coupled to an outlet (17) from the hopper (10) via a valve assembly (18). The conduit (20) also has another inlet (21) into which a conveying air supply is introduced. Powder is introduced into the conduit (20) via the valve (13) and is conveyed along the conduit (20) by the conveying air supply (22), in the example described the powder is diatomaceous earth which is to be mixed with brine in a slurry tank (61). The outlet (62, 63) connected to the conduit (20) are submerged in the brine in the slurry tank (61) and shearing and diffuser plates (68) are provided to break up the powder as it rises to the surface (69) of the brine in the slurry tank (61) to prevent any atmospheric contamination above or around the slurry tank (61) by any unvetted diatomaceous earth powder. <IMAGE>

Description

"Powder Transfer System" This invention relates to a powder transfer system for transferring powder from a first location to a second location.

When mixing powders with water a normal procedure is to empty the powder into a tank containing water which is typically in a brine solution with an agitator to mix and prevent settling of the powder. However when dealing with powders it is desirable that the powder to be mixed with the water is prevented from entering into the environment.

Powders such as diatomaceous earth are used off-shore for the purpose of mixing with a water solution to provide a filtration media. This is normally carried out by a user pouring the diatomaceous earth from a bag into a mixing vessel containing the brine. This method of providing a filtration media for offshore use has the disadvantage of a quantity of the diatomaceous earth entering in to the environment and causing harm to the user. This method also results in a poor mixing of the water solution and diatomaceous earth with much of the diatomaceous earth being unmixed and consequently wasted.

According to the present invention there is provided a powder transfer system comprising means for creating a flow of fluid between a first location and a second location, an enclosed transfer conduit extending from the first location to the second location, an inlet at a third location between the first and second locations for introducing powder into the conduit and an outlet at a location downstream of the third location for removing powder from the conduit.

Further according to the present invention there is provided a method of transferring a powder comprising the steps of creating a flow of fluid between a first location and a second location, introducing powder into the flow of fluid at a third location between said first and second locations, and removing the powder from the flow of fluid at a location downstream of the third location.

Preferably, the means for creating the flow of fluid in the enclosed transfer conduit is an air pump.

Preferably, the pressure of fluid in the flow is in the region of 5 to 10 p.s.i, and this is especially advantageous where the powder is a diatomaceous earth such as DIT 2R. Most preferably, the fluid pressure is 7.5 p.s.i.

Preferably, the fluid flow is in the region of 20 to 30 c.f.m, and this range is especially advantageous where the powder is a diatomaceous earth such as DIT 2R.

Most preferably, the fluid flow is 26 c.f.m.

Preferably, the system includes a valve assembly at the inlet which controls discharge of powder into the enclosed transfer conduit. Typically, the valve assembly may comprise a rotary valve.

Preferably, the motorised valve assembly discharges powder at a rate up to at least lOkg/minute allowing a continuous flow of powder.

Preferably, the system may also include a holding means, the valve assembly being located between the enclosed transfer conduit and the holding means.

Typically, the holding means may be in the form of a holding hopper which may have an inclined base for ease of flow of the powder.

Preferably, the angle of the inclined base in the holding hopper is in the region of 2" to 15 , especially when the powder is a diatomaceous earth such as DIT 2R.

Most preferably, the angle of the inclined base is io".

Preferably, located at the base of the holding hopper is means to improve the flow of powder in the holding hopper. Typically the means to improve the flow expels a fluid along the base of the holding hopper and through a perforated plate and into the powder to improve flow of the powder.

Preferably, the fluid pressure in the means to improve the flow is in the region of 1 to 10 p.s.i, especially where the powder is a diatomaceous earth such as DIT 2R. Most preferably, the fluid pressure in the fluidised bed is 3 p.s.i.

Preferably, the fluid flow in the fluidised bed is in the region of 50 to 200 c.f.m, especially where the powder is a diatomaceous earth such as DIT 2R. Most preferably, the fluid flow in the fluidised bed is 97 c.f.m.

Preferably, the outlet of the enclosed transfer conduit is located within a mixing vessel containing water. More preferably, the outlet is located below a baffle plate in the mixing vessel. Preferably, holes in the baffle plate allow the powder and water to be mixed preventing large quantities of unmixed powder to reach the surface of the water.

An example of a powder transfer system in accordance with the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a schematic view of a powder transfer system; Fig. 2 is an isometric view of a fluidising air distribution arrangement for use with the powder transfer system shown in Fig. 1; and, Fig. 3 is a schematic diagram of the air supply and control system for the powder transfer system shown in Fig. 1.

Fig. 1 shows a powder transfer system which comprises a hopper 10, which has an outlet 17 coupled to a rotary valve 18. The hopper 10 has a false floor 12 with a large number of small perforations which permit the storage region 11 of the hopper 10 to communicate with a space 14 located between the false bottom 12 and base 13 of the hopper 10.

Located below the base 13 is an air supply line 1 (Fig.2) which supplies an airflow to the perforations in the false base 12 so that air flows through the perforations into the storage region 11 of the hopper 10. The air supply line 1 has an inlet connector 7 for connecting the air supply line 1 to an air supply. The supply line 1 comprises a number of pipes connected by flanges 3 so that the air supply line 1 extends in an approximately square shape below the base 13. In the centre of three of the four sides of the square formed by the supply line 1 is a T-junction 4 which permits air in the supply line 1 to flow to an outlet nozzle 2 via a connecting flange 3.On the fourth side of the square formed by the supply line 1 is a bend formed by a corner piece 5 bent upwardly through an angle of 90 to meet a flange 3 which connects the end of the supply line 1 to a fourth and final outlet nozzle 2. The outlet nozzles 2 extend through the base 13 and feed air into the space 14. The supply line 1 also includes a pressure relief valve 6 which is in the form of a burst disk. This permits venting of the air supply line 1 should the pressure in the air supply line 1 become too high.

The outlet from the rotary valve 18 is connected to an air conduit 20 by means of an inlet 19. An inlet 21 to the conduit 20 is connected to an air supply 31 (see Fig. 3) which generates an air flow 22 in the conduit 20.

Mounted on the side of the hopper 10 is a control panel 30 which has the controls necessary for operating and controlling the powder transfer system. A schematic diagram of the air supply and control system is shown in Fig. 3. The air supply 31, which may be an air pump or any other suitable form of air supply, is coupled to a main supply conduit 32 which has a main on/off valve 33 and water trap/filters 34 to filter the air from the supply 31 before use. The air from the main supply conduit 32 is supplied to three parallel supply lines 33, 34 and 35. The air in the supply line 3 passes through a pressure regulator 36 and then a quarter turn ball valve 37 before passing through a 7 mm orifice plate 38 which controls the flow of air 22 through the conduit 20.A pressure gauge 39 is located between the ball valve 37 and the orifice plate 38 and a second pressure gauge 40 is located between the orifice plate 38 and the conduit 20. The orifice plate 38 is chosen to be 7 mm so that the air flow through the conduit 20 is approximately 26 cfm.

The air supply line 34 supplies air to the supply line 1 located below the base 13 of the hopper 10. The supply line 34 has a pressure regulator 41 and a on/off valve 42. An orifice plate 43 is also positioned in the supply line 34 and controls the flow of air to the supply line 1. Typically, the orifice plate is 14 mm and gives an air supply of approximately 97 cfm in the supply line 1. The burst disk 6 is designed to burst at a pressure of 5 psig to ensure that the supply line 1 is not over pressurised and so acts as a pressure relief valve for the whole enclosed storage region II.

Pressure gauges 44, 45 are located on either side of the orifice plate 43 to monitor the pressures on either side of the orifice plate 43.

The supply line 35 supplies air through a pressure regulator 46 to a rotary speed control valve 47, which controls the velocity of the air flow in the control line 35, and an on/off valve 48. The air in the control line 35 then passes through an oiler 35 before driving an air motor (not shown) which in turn drives the rotary valve 18.

Coupled to the rotary valve 18 are counters 50, 51 which send an output signal to a rotary valve sender unit 52. The output from the sender unit 52 acts as feedback to the counters 50, 51 enabling the output of powder to be monitored.

Returning to Fig. 1, the conduit 20 which is typically a flexible conveying hose which may have a diameter of 50 mm is coupled to an input conduit 60 of a slurry tank 61. The input conduit 60 bisects into two separate conduits, 62, 63 which may be isolated by control valves 64 from the inlet conduit 60. The conduits 62, 63 extend into the separate tanks 66, 67 respectively and have their openings adjacent base 65 of the slurry tank. Adjacent the end of the conduits 62, 63 are shearing and diffusing plates 68. Each plate 68 has a number of perforations in it, and the size of the perforations is such that lumps of powder are broken up and diffused as they pass through the perforations.

Typically, the conveying hose 20 is detachable from the inlet conduit 60 to permit the hopper 10 to be transported independently of the slurry tank 61.

In use, the hopper 10 may be filled with a powder in an enclosed environment and typically, the powder may be a diatomaceous earth which may be mixed with brine to form a filter media for use on off-shore platforms for recovering oil or gas. The hopper 10 with control panel 30 and the air supply and control system shown in Fig. 3 may be housed in a container for transportation to an off-shore platform or installation.

When the hopper 10 arrives at the off-shore installation, an operator connects the conveying hose 20 to the inlet 60 of the slurry tank 61. Then the air supply 31 is turned on and air allowed to flow through the supply line 32 by opening the valve 33. Valve 37 is then opened to pass air through the conveying hose 20 via inlet 21. Valve 42 is opened to permit the air supply into the supply line 1 which then passes through the outlets 2, through the false space 12 and into the powder in the main storage area 11 of the hopper 10.

The air passing through the false base 12 into the main storage area 11 helps to fluidise the powder in the hopper 10 and reduces the possibility of powder clogging the outlet 17.

The valve 48 and supply line 45 is then opened and the rotary valve 47 adjusted to drive the rotary valve 18 at the correct speed to obtain the required rate of dispensing of the powder from the hopper 10 into the conveying hose 20.

As the powder is dispensed into the conveying hose 20 by the rotary valve 18 it is carried by the conveying air supply 22 along the conveying hose 20 to the inlet 60 of the slurry tank. The operator will have already opened the valves 64 and so the conveying fluid with the powder being carried in it is carried into and through the conduits 62, 63 and discharged from the ends of the conduits 62, 63 into the tanks 66, 67.

The tanks 66, 67 are filled with fluid up to the fluid level line 69 indicated in Fig. 1. Typically, the fluid is brine where the powder is diatomaceous earth.

However, the fluid in the tanks 66, 67 could be varied in order to suit the particular powder which is to be dissolved or held in suspension.

When the conveying air 22 and powder pass through the outlets of the conduits 62, 63, the air and powder rise towards the surface of the fluid and pass through the shearing and diffuser plates 68 which break up the powder and ensure that bubbles of non-wetted powder do not burst on the surface of the fluid releasing powder into the atmosphere.

In the particular example described above the storage area 11 of the hopper 10 typically holds about 2 tons of diatomaceous earth such as DIT2R. Typically the false base 12 is inclined at an angle of approximately 10 to the horizontal where the powder is diatomaceous earth. However, other angles could be used depending on the particular flow characteristics of the powder which is being transferred.

Typically, using the system described above, diatomaceous earth may be moved at rates of up to at least 50 kg over a 4i minute period to the tanks, 66, 67 where the conveying hose 20 has a length of approximately 10 m. The shearing and diffuser plates 68 typically have apertures which are approximately Ys of an inch in size and each hole may be spaced approximately 4 inches apart.

Hence, by using the powder transfer system, the user is not directly exposed to the diatomaceous earth (or other powder) and therefore contact with the powder is mitigated.

The powder transfer system also provides an effective means of mixing the fluid and the powder together and the system 1 permits the process to be carried out in bulk and off-shore where, in the case of diatomaceous earth and brine, the resulting filtration media can be used directly without the need for transferring it.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims

CLAINS

1. A powder transfer system comprising means for creating a flow of fluid between a first location and a second location, an enclosed transfer conduit extending from the first location to the second location, an inlet at a third location between the first and second locations for introducing powder into the conduit and an outlet at a location downstream of the third location for removing powder from the conduit.

2. A powder transfer system according to Claim 1, wherein the system also includes a holding means, an outlet from the holding means being coupled to the inlet at the third location of the enclosed transfer conduit and the holding means holding the powder to be transferred.

3. A powder transfer system according to Claim 2 wherein the holding means includes an inclined base which is inclined downward towards the outlet of the holding means.

4. A powder transfer system according to Claim 2 or Claim 3, wherein the system also includes means to improve the flow of powder in the holding hopper.

5. A powder transfer system according to Claim 4, wherein the means to improve the flow includes a conduit which forces air into the powder in the holding means adjacent to the base of the holding means.

6. A powder transfer system according to any of Claims 2 to 5, wherein a valve assembly is coupled between the outlet of the holding means and the inlet at the third location to control the introduction of powder into the conduit.

7. A powder transfer system according to Claim 1, wherein the system includes a valve assembly at the inlet at the third location which controls the introduction of powder into the enclosed transfer conduit.

8. A powder transfer system according to Claim 6 or Claim 7, wherein the valve assembly comprises a rotary valve.

9. A powder transfer system according to any of the preceding Claims, and further including a mixing vessel, the outlet of the enclosed transfer conduit being located in the mixing vessel.

10. A powder transfer system according to Claim 9, wherein the outlet of the enclosed transfer conduit is situated adjacent the base of the mixing vessel.

11. A method of transferring a powder comprising the steps of creating a flow of fluid between a first location and a second location, introducing powder into the flow of fluid at a third location between said first and second locations, and removing the powder from the flow of fluid at a location downstream of the third location.

12. A method according to Claim 11, wherein the fluid flow is in the range 20 cfm to 30 cfm.

13. A method according to Claim 11 or Claim 12 wherein the method further includes removing the powder from the flow of fluid by passing the flow of fluid with the powder through a liquid.

14. A method according to Claim 13, wherein the step of removing the powder from the flow of fluid further includes passing the flow of fluid with the powder through a perforated plate submerged in the liquid.

15. A powder transfer system substantially as hereinbefore described with reference to the accompanying drawings.

16. A method of transferring a powder substantially as hereinbefore described with reference to the accompanying drawings.