WO2007004899A1

WO2007004899A1 - Fluidising apparatus for transfer of particulate material

Info

Publication number: WO2007004899A1
Application number: PCT/NZ2006/000167
Authority: WO
Inventors: Darryl John Sinclair
Original assignee: Darryl John Sinclair
Priority date: 2005-07-01
Filing date: 2006-06-30
Publication date: 2007-01-11

Abstract

A product fluidising apparatus comprising a chamber having at least one product inlet controlled by a first valve and adapted to receive a product supply, at least one gas inlet controlled by a second valve and adapted to receive a pressurised gas supply, and at least one product outlet which is connectable to a pressurisable product delivery pipe and which is controlled by a third valve. The first, second and third valves are provided with actuators capable of cycling each valve from a substantially open position to a substantially closed position. And, the apparatus includes a controller capable of controlling and cycling the operation of each valve in sequence, in such a manner that while the first valve is substantially open the second and third valves are substantially closed, and while the first valve is substantially closed the second and third valves are substantially open.

Description

FLUIDISING APPARATUS FOR TRANSFER OF PARTICULATE MATERIAL

FIELD OF THE INVENTION

This invention relates to a fluidising apparatus and method, and in particular, but not exclusively to a fluidising apparatus and method for use in the conveying of particulate material.

BACKGROUND

Particulate materials are often transported by trucks and stored in large silos. The transfer of the particulate material from a truck to a silo, or visa versa, is usually carried out by fluidising the. material and then pumping it through large pipes. Air is separated from the material at its destination.

Two main methods are used to convey the material from one vessel to another, these being ''dense* 'p^'lϊase'^* and' ''light phase" conveying. ^'" 'Light phase" conveying is^' sometimes also referred

''dilufe^'phase" cohveyin'g. ^{; !}

In the case of dense phase, a pressure vessel, for example a road tanker or a ground silo, is filled with product and then sealed and pressurised to approximately 22 pounds per square inch (psi). During this process air is pumped into, the product fhrough aerators, fluidising the. product. Once the operating pressure has been reached^ the discharge valves are opened and product is forced, under pressure, from the vessel and, into the silo. An operating pressure pf at least 75% of the initial vessel pressure must be maintained for effective operation.

The light phase method is one in which, the product is typically introduced, into a "live air Stream'' via a lotary' sty^e, valve.; Operating . pressures, vary, accprding to the application but are typically within the range of 5.tθj;12,psi, ._;This method works, on. the, principle that, a head pf product in a vessel above the valve will provide the necessary back pressure to overcome the φressure of the air stream' within a delivery line, -to enable¹ effective 'transfer of the product ^"from the^' vessel iήto'the delivery .line.^{1 ;} Ho weveryϊή' practice, this only works while a sufficient niags of product remains iir the, vessel.;. For, example, when conveying, say 1300 tόrtoes , of cement from_. a . silo, the system will work well .for' about an hour, but, then ;'^fblpw by" will¹ occur. Thisis where pressurised air from the delivery line blows past _.the rptary valve and up into the silo, causing the transfer rate to drop. The excessive aeration of the product can also cause both operational and environmental problems - this action can accelerate the wear on the rotary valve, and it can cause the release of dust if the silo or vessel is open to the surrounding atmosphere.

5 The fluidising beds, the pressure vessels or the associated valves and pipework can be expensive and can require a significant amount of maintenance. The systems are also prone to, blockages and other malfunctions. And where the particulate material is abrasive, the maintenance requirements can be more burdensome. In situations where the vessel is pressurised, the vessels have additional structural and manufacturing requirements, as well as 0 maintenance and inspection requirements.

Spills of the particulate material inevitably occur and it can be difficult to collect the material and pump it into a storage vessel again. Systems which are essentially closed, and which require, an internal pressure . to operate, are not suitable for recovering material that has spilled from the system.

5 OBJECT

It is th^'έf efόre aii' object of the^* 'present invention^' to' provide a fluidising apparatus and method which will at least' go some way towards overcoming the above mentioned problems, 8r at least provide the public with a useful choice.

STATEMENTS OF THE INVENTION

0

yalve.means;. and... adapted to.receive a pres.surised gas supply,- and at lqast one _; product_. putlet whϊch ϊs'connectable tp a pressurisable product .delivery pipe and .which is, controlled by a 5 third . yalye._: means, . the first,; .second and third valve means, being provided , with, .aptuatiqn means ; capable .; of I cycling , each valve means , frpm a substantially ppen position to a substantially, closed position, and wherein the₍ apparatus _.includes control means _: capable; of

; ^{■ ■} controlling and cycling the operation of each valve means in sequence in such a manner that while the first valve means is substantially open the second and third valve means are substantially closed and while the first valve means is substantially closed the second and third valve means are substantially open.

Such an apparatus is advantageous in that it can be used to fluidise a particulate material without the need to pressurise the particulate material storage vessel, or without the need to use a rotary valve with its associated operational and maintenance problems.

Preferably the third valve means is sequenced to begin opening a short time after the second valve means begins to open.

Preferably the apparatus further includes a fourth valve means adapted to control the flow of a pressurised gas flow "which can pass directly into the pressurϊsable' product delivery pipe at a^' location^' immediately downstream of the third¹ valve' means. ^'' "^'' "

Preferably the fourth valve means includes actuation means and the control means is capable 6f cycling the fourth: valve 'means iti sequence' with the other ''VaIvW means.⁵ '

Preferably., the .fourth, .valve, means is sequenced: to , be, .in , an at ..least partially closed configuration during at least part of the time that the second valve means is substantially open.'

Preferably the fourth valve means is sequenced to be in a substantially open configuration during ^''at^* least part of the time^' that the second valve means is substantially closed. ^; " ' ^' ' ' ^{* ■}

P rjefeX abh/jaj. ieastoniJ; of the,^:valye means is a butterfly, valve; '

In, $ second;, aspect,^;, the; invention may be ..said to., consist, in.. a .particulate .material storage facility øv

flμidjsing.-, apparatus ^■ substantially ^: as specified herein- :^■■ ^{! ■}

In a third aspect, the invention may be said to consist in a method of fluidismgia _.produc.t including' the steps of; ^{■ ■ '} • substantially opening a first valve means associated with a first inlet opening of a chamber to allow a quantity of product to be deposited into the chamber via the first inlet,

substantially closing the first valve means,

substantially opening a second valve means associated with a second inlet of the chamber, and substantially opening a third valve means associated with an outlet of the chamber, to allow a compressed gas to flow into the chamber via the second inlet and to carry the deposited product out of the outlet of the chamber and into a product delivery pipe,

substantially cldsihg the second and the third valve⁵ means, arid '

then repeating the above cycle as desired.

Preferably the opening of the third valve means is timed to occur a short time after the opening of the second valve means.

Preferably the method further includes the at least partial closing of a fourth valve means in a pressurised gas, supply line which is connected directly to the product delivery pipe, when the second, Va₁IVe means is opened, and then moving the fourth valve to.amore open, position when the s_.ecqnd valve means is substantially closed.

The invention _^may also be said to consist in the .parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of 'any two or mof e of the parts, elements or features, and where specific integers are mentioned herein which have known equivalents, such equivalents are incorporated herein as if they were individually set forth.

DESCRIPTION

Further aspects of the present invention will become apparent from the following description which is given by way of example only and with referenbe to the accompanying drawings in which: FIGURE 1 is a schematic view of a fluidising apparatus,

FIGURE 2 is an electrical diagram showing a control system for use with the fluidising apparatus, and

FIGURE 3 is an electrical diagram showing an alternate control system for use with the fluidising apparatus.

With reference to Figure 1, a fluidising apparatus (10) is shown comprising a cylindrical chamber (11) having three openings, a product inlet (13), a pressurised air inlet (15) and a product outlet (17). The product inlet (13) is situated at a high point on the chamber (11) which allows product to be dropped into the chamber through the inlet (13). Alternatively, the product inlet (13)' can "take a lower riosition on the chamber (11) if, for example, the product is, to be augered into the chamber (11). The product outlet (17) is adapted to be connected to a product delivery pipe (19) which can guide the product to another location, for example into a transporter, or into a storage silo. The apparatus (10) is designed primarily to fluidise product in the form of particulate material, for example cement. ^! ' "

While the apparatus (10) could comprise a number of pressurised air supply configurations, a simple and effective configuration is shown. com'prising a single pressurised air source (not shown),^~frόm a^* blower for example', which is supplied via a non return valve (21) and' which then divides into two flow paths, a first flow path' (23) which supplies pressurised air to the air«mlet (15) of 'the 'chamber (4 iχ and a second flow path (25) which by-passes the chamber (11) and supplies air directly into the product delivery pipe (19).

A system of four valves is used to control the flow of product and compressed air to allow the apparatus to operate effectively. A first valve (27) controls the opening of the product inlet (13), a second valve (29) controls the opening of the air inlet (15), a third valve (31) controls the opening of the product outle^ (17) and an optional fourth valve (33) controls the flow of pressurised air in the second flow path (25) which is supplied directly to the product delivery pipe (19). The second flow path (25) connects to the produbt delivery pipe (19) at a location immediately downstream of the third valve (31). A suitable valve type for use 'in this application is a butterfly valve. Other valves type can be used, for example' gate valves or ball valves, however the relatively rapid control possible using a butterfly valve is considered advantageous.

The apparatus (10) operates to fluidise a product and to supply the fluidised product into the delivery pipe (19). This is achieved by operating the second and third valves (29 and 31) to restrict the flow of the pressurised air into and through the chamber (11) and then allowing a particulate product to enter the chamber (11) via the product inlet (13) by opening the first valve (27). The product can be presented to the product inlet (13) by a number of means for example by gravity from a storage vessel above the chamber (11), or by augering the product to the product inlet (13), or even by manually shovelling the product, or emptying bags of the product, into the product inlet (13). *

The first valve (27) then closes and the second and third valves (29 and 31) open allowing pressurised air to enter the chamber (11) and fluidise the product and carry it into the delivery pipe (19). Then the second and third valves (29, and 31) close ahd^; the cycle is repeated.) The timing of the opening of the third valve (31) 'can be¹ slightly out of phase With the opening ^"of the second Valve (29), as will be= explained -below;' to improve¹ the efficiency of the 'apparatus (10)v

Air flowing through, the second flow path, (25) ensures that the. product continues to move along the delivery pipe (19). The apparatus (IQ) is .shown having the second flow path (25) meeting the product delivery pipe, (19) at an angle (35) of about 45 degrees. Angles (35) of between 30. and 60 degrees are considered suitable,, ,

With reference to both Figures 1 and 2, the operation and. control of an embodiment of tlie apparatus (10) is explained in further detail.. Figure 2, is, an ,_t electrical diagr_^am showing wiring connections of, a cpntrόl_rsystem (37), the components be|ng. powered by an electrical power, supply haying a phase line (39) and a neutral line (4,1).

Eacϊi vaϊve (27), i(29), (31) and (33) can be actuated ty its own pneumatic actuator, and can be controlled ]by its own solenoid operated valve, (μot shown), and a cam operated switch (not shown) is located on .the actuator of the first, second' arid third valves (27), (29) arid (31 ). In this example, the first valve (27) is actuated by a first actuator (43), has a first cam operated switch (Cl) and is controlled by a first solenoid (Sl), the second valve (29) is actuated by a second actuator (45), has a second cam operated switch (C2) and is controlled by a second solenoid (S2), the third valve (31) is actuated by a third actuator (47), has a third 5 cam operated switch (C3) and is controlled by a third solenoid (S3), and the fourth valve (33) is actuated by a fourth actuator (49) and is controlled by a fourth solenoid (S4).

The . solenoids (Sl to S4) are single coil, or self return, style solenoids and operate a pneumatic valve, and when power is applied to the coil of the solenoid its associated pneumatic valve allows air to be exhausted from one side of the respective actuator (43 to 0 49) as air is applied to the opposing side.

A first timer (Tl), controls the filling time, that is, the time that the first valve (27) is , open and allowing product to enter the chamber (11). A second timer (T2) controls the chamber (11) empting time, that is, the time that the second and third valves (29 and 31) are .open.

hϊ'ihe ^μpbwer ^'off^5' State, ^;the^; third^' switch: (C3)ϊs closed; the^' first switch' (Cl) is'clόsed,^' the ^; 5 second switch (C^'2)¹ ls'dperii; arid ^'all 'the valves' 'exdepf the foύ^"rtri^!valve (33) are in the closed position. The fourth valve (33) is normally open and is powered towards the closed position.

Ih tile "power on" state, :'a' Sequence of valve actuations is achieved by the operation of the cόήrrbi system (37). When power is applied the sequence will normally begin ^'with the third switch (C3) configured to allow power to flow to the first timer (Tl) and to the first solenoid 0 ($!)-_, The first valve (27) will open, taking approximately one second. The, first ^'valve (27) opens, for the preset time of the first timer (Tl), allowing product to e,nter the chamber (11) via the product inlet (13). The action of the first valve (27)_,ibeginning to open causes the first switch (Cl) to open, resetting the second timer (T2).

, .. )iVhen,,the ^jfή-st .ømer ■ (Tl)..reaches, its. ₍preset time • a pair, of first Jimer contacts_. (Tl a) opens, 5 cutting power to the first solenoid (Sl). The first valve (27) will then close. ,

(27) . is fully, closed _; the -first , switch (C I₁) f allows power to , flow-to the second solenoid (S2) and to the second. timer (T2). The second valve (29,) -will .then begin to . '■ ^■ open., , When the second valve (29) reaches 25% of its opening travel, the second switch (C2) closes momentarily, by the action of its associated cam, and this latches a first relay (R3), and this closes two pairs of contacts, a first pair of contacts of the first relay (R3a) and a second pair of contacts of the first relay (R3b), to allow power to flow to both the third solenoid (S3) and 5 to the fourth solenoid (S4).

The third valve (31) will then begin to open and the fourth valve (33) will begin to close to 75% closed. The slight lag of the third valve (31) opening, generally less than a second after the second valve (29) begins to open, can be important, because the initial rush of air that is let into the chamber (11) via the pressurised air inlet (15) by the second valve (29) can lift 0 and fluidise the product within the chamber (11) momentarily before the third valve (31) opens'.¹' *

It is envisaged that for products. like cement that it would be preferable to limit the filling of the chamber (1,1) to a depth of not more than 100 millimetres (mm) to ensure that fluidisation of the prodμct will occur rapidly. It is also desirable to configure the second valve (29) so 5 that the initial air that passes the valve as it begins to open will be directed towards the bottoriϊ 'of the- chamber -(H¹) so that the air will tend to'get under the product. The chamber (11)^; could^; be enhanced to¹ include- ducting, and' optionally a fmidising bed, to h'elp the inconliήg air to get under the product.

i ,, The fourth valve (33) is configured to stop closing at 75% closed,, by a mechanical stop. in 0 the fourth, actuator (49). This partial closing of the fourth valye (33) means that the. pressurised air &qw is directed mainly through the chamber (11) to clear the product from the chadiber (l^'and to mόv& it out through the, product outlet (17) and into the product

flow 'of_. airy bpth via the

via the^' product delivery pipe ^'( 19) to its destination.

5 Wh^QQ the third valve (3,1), has rnoved from the .closed position, the circuit to the first timer (T I)₁ is, broken.by the. third switch (C.3) opening causing the first timer (Tl ) to, reset. _.. _,. .

Trie second ariiϊ third valves, (29) and (31), remain open for the preset time of the second timer (T2). ", When the second timer (T2) reaches its preset time a pair of contacts, a first pair of contacts of the second timer (T2a) and a second pair of contacts of the second timer (T2b), will open. This opens the circuit to the second, third and fourth solenoids (S2), (S3) and (S4). The fourth valve (33) will fully open, and the second and third valves (29) and (31) will fully 5 close.

The first relay (R3) is required to latch because of the action of the second cam switch (C2), as it momentarily closes during both the opening and the closing of the second valve (29). The second pair of contacts of the second timer (T2b) prevent the first relay (R3) re-latching while the second valve (29) is closing.

0 When the third valve (31) is fully closed, the third switch (C3) will be closed again, allowing power to flow to the first timer (Tl) and to the first solenoid (Sl). The first, valve (27) will open, resetting the second timer (T2)₅ allowing the cycle to begin again.

Note! the' contacts la^'belled (TIa)₅ (T2a), (T2b) and (PIa) are normally closed, and are powered to open.

5 Tf an over pressure is sensed by a pressure sensor (51), its associated pressure switch (PS) is triggered and its associated pressure switch relay (Pl) energises the first and second contacts of the pressure switch relay (PIa) and (PIb) causing each to change state. 'This interrupts the cycle described above by resetting the second timer (T2) and holding the first relay (R3) in

, , the on statp, thereby applying power to the second and third solenoids (S2) and (S3) until the 0 pressure drops, at which time the cyple can begin again.,

Throughout 'the 'above sequence the fourth valve (33) ,'maintairis an Uk flow in the delivery pipe while the _f chamber (11) is,» filling and this ensures thaj there is a constant flow of air in the delivery pipe (19) up to a silo or tanker. Otherwise the product may not transfer, it would likely block the delivery pipe (19) on horizontal sections or simply fall back down in any 5 Vertical sections if constant airflow was not maintained.

By closing the fourth valve (33) to 75% closed and redirecting the air through the chamber (11) it ensures that all product in the chamber (11) is removed and it prevents any back pressure from blocking the second flow path (25) between the fourth valve (33) and where it joins the product delivery pipe (19).

The fourth valve (33) operates in reverse to the other valves, it requires power to close, all other valves require power to open. This is a safety feature, should the power supply to the valves become interrupted the fourth valve (33) will remain open allowing the pressurised air to bypass the chamber (11).

The timing of the sequencing of the valves (29 to 33) of the apparatus (10) is adjustable from both the cam switches (Cl to C3) on the actuators and the first and second timers, (Tl) and (T2), to suit the product and the application.

Initial iestiiig^{' J}by the' inventor;¹ using an apparatus (lθ)'as described' dbόve, having 'a 100 nitri diameter ^:pf e'ssurised ^' air supply line and a 200 mm diameter chamber with a 200 mm djameter first valve,, and operating at 5 to 12 psi ajαd at a rate of 1800 cycles per hour, will fluidise up to 15 tonnes of cement per hour.

With reference to Figure 3 an electrical diagram' 'showing^' the wiring connections^' of ah alternate' control¹ system (53) is provided. The control system (53) is similar to the previously described control system (37) except for the addition of an optional switch (S5) which, allows the. closing of the fourth valve (33) to be timed to coincide with the opening of first, valve (27) or wjth the second valve. (29). In the previous control system (37) described with reference to figure 2 above, the closing of the fourth valve (33) can only be timed to cόitieide with the^' Opening" "of thfr second valve (29)1 ' " '

With the alternate control system (53), when a connec.ti.pn is made, through a first contact (!35a) of the switch (S5),^' the fourth valve (33) is sequenced to niove towards closed when the first valve (27) closes. This means that when the second valve (29) is subsequently "opened a greater air pressure can' be initially available to enter the chamber (H) to' iluidise the material in the chamber (H). This configuration and operating sequence is more suitable to move heavier particulate material such as cement, which can be, relatively, difficult to _. move;- '

When a connection is made through a second contact (S5b) of the switch (S5), the apparatus will operate as described with reference to figure 2, that is, fourth valve (33) is sequenced to move towards closed when the second valve (29) reaches 25% of its opening travel. This gives a smoother or gentler transition of air flow between the first flow path (23) and the second flow path (25). This configuration and operating sequence is more suitable when the fluidising apparatus (10) is to be used to fluidise softer particulate material, for example coffee beans or barley, which may otherwise be damaged.

VARIATIONS

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applicatibhs of the invention will suggest themselves 0 without departing from' the scope of* the invention as defined hi the appended claims. The disclosures arid the description herein are purely illustrative and are not intended to be in any senseTimiting.

The above, example uses, a third valve (31.) haying an actuator. An alternative configuration of the apparatus (10) could use a non return valve in this location, however the use of a non 5 return valve could give rise to reliability problems as the valve may not close positively whejϊ it becomes dirty.

The above. example_, μses a control, system comprising . earn operated switches, timers, relays contacts,, and solenoid operated valves, A range of alternative control systems could be used, , ,., fpr₍ example /microprocessor based systems, or purely .mechanical systems. , However it is 0 considered that the control system described is^; suited_, to the operating environment found in many fluidised product conveying applications and is cost effective and simple to maintain and adjust... .

The above example uses pressurised air to fluidise and carry the product, but it is enyisaged that in some applications a specialised gas, for example an inert gas, may be used.

5 The fluidising apparatus (10) has primarily been described with reference to fluidising cement_;, however the apparatus can be used to fluidise a range of products,, for example

^' - ^' V-: ; ^' \; ^:\ .y :' V.^'. ' i . ^{" '} .- ^{'■ ■ ' ■} ' " ^{"■ ■ ■} " : ! , ^■ ; :^{' •}. . ,/ ^' ; ^■. v ., ' ^{' :} v ^{' '}•' ^'. ^{" ' '• ■ "}. ' ^■ . ^{' ■} ' ." ^{' •} ' ^{; •} ' ^". ' including cement,, ash, beans, grain, flour, sugar, etc._. DEFINITIONS

Throughout this specification the word "comprise" and variations of that word, such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps.

Claims

1. A product fluidising apparatus comprising a chamber having at least one product inlet controlled by a first valve means and adapted to receive a product supply, at least one gas inlet controlled by a second valve means and adapted to receive a pressurised gas supply, and at least one product outlet which is connectable to a pressurisable product delivery pipe and which is controlled by a third valve means, the first, second and third valve means being provided with actuation means capable of cycling each valve means from a substantially open position to a substantially closed position, and wherein the apparatus includes control means capable of controlling and cycling the operation of each valve means in sequence in such a manner that while the first valve

^! means is substantially open the second and third valve means are substantially closed and while the first valve means is substantially closed the second and third valve means are substantially open.

2. A¹ product fluidising apparatus as claimed in claim 1, wherein the third valve means is sequenced to begin opening a short time after the second valve means begins to open. ' >

3. A product fluidising apparatus as claimed in any preceding claim, wherein the apparatus further includes a fourth valve means adapted to control the flow of a pressurised gas flow which can pass directly into the pressurisable product delivery pipe at a location immediately downstream of the third valve means.

4. A product fluidising apparatus as claimed in claim 3, wherein the fourth valve means includes actuation means and the control means is capable of cycling the fourth valve means in sequence with the other valχe means.

5. A product fluidising "apparatus as claimed in any one of claims 3 or 4, wherein the fourth valve means is sequenced to be in an at least partially closed configuration during at least part of the time that the second valve means is substantially open.

6. A product fluidising apparatus as claimed in any one of claims 3 to 5, wherein the fourth valve means is sequenced to be in a substantially open configuration during at least part of the time that the second valve means is substantially closed.

7. A particulate material storage facility, or a particulate material transporter, incorporating at least one fluidising apparatus substantially as claimed herein.

8. A method of fluidising a product including the steps of;

substantially opening a first valve means associated with a first inlet opening of a chamber to allow a quantity of product to be deposited into the chamber via the first inlet,

substantially closing the first valve means, ₍

substantially opening a second valve means associated with a second inlet of

, the chamber, and substantially opening a third valve means associated with an v outlet of |he chamber, to allow a compressed gas to flow into the chamber via the second inlet and to carry the deposited product out of the outlet of the chamber and into a product delivery pipe,

substantially closing the second and the third valve means, and

then repeating the above steps as desired.

9. A method of fluidising a product as claimed in claim 8, wherein the opening of the third valve means is timed to occur a short time after the opening of the second valve means. ^!

10. A method of fluidising a product as claimed in any of claims 8 or 9, wherein the method further includes the at least partial closing of a fourth valve means in a pressurised gas supply line which is connected directly to the product delivery pipe, when the second valve means is opened, and then moving the fourth valve to a more open position when the second valve means is substantially closed.