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WO2003068634A1 - Dispositif de decompression pour silos - Google Patents

Dispositif de decompression pour silos Download PDF

Info

Publication number
WO2003068634A1
WO2003068634A1 PCT/GB2003/000606 GB0300606W WO03068634A1 WO 2003068634 A1 WO2003068634 A1 WO 2003068634A1 GB 0300606 W GB0300606 W GB 0300606W WO 03068634 A1 WO03068634 A1 WO 03068634A1
Authority
WO
WIPO (PCT)
Prior art keywords
lid
pressure relief
relief device
counterbalance
pivot
Prior art date
Application number
PCT/GB2003/000606
Other languages
English (en)
Inventor
William Liddle
Original Assignee
Rmc Readymix Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rmc Readymix Limited filed Critical Rmc Readymix Limited
Priority to AU2003245770A priority Critical patent/AU2003245770A1/en
Publication of WO2003068634A1 publication Critical patent/WO2003068634A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D90/00—Component parts, details or accessories for large containers
    • B65D90/22—Safety features
    • B65D90/32—Arrangements for preventing, or minimising the effect of, excessive or insufficient pressure
    • B65D90/34—Venting means

Definitions

  • the present invention relates to pressure relief devices for use on silos containing particulate matter.
  • the invention relates to an improved pressure relief device having improved opening and flow characteristics and for use on silos which are filled using a pressurised means such as pneumatic conveyance.
  • Silos are a common means of storing particulate matter such as cement powder or grain.
  • the silos are filled from vehicles such as tankers by means of pneumatic conveyance, wherein the contents of the tanker are conveyed into the silo by means of a flow of pressurised gas, typically air.
  • the silos themselves are not designed as pressure vessels and typically have a maximum working pressure limited to 6.9 KN/m/m (1 psig) . As such, there is a danger that when filling such silos by means of pneumatic conveyance or other similar means that the silo may become over-pressurised and subject to damage or explosion.
  • Pressure relief devices for such silos are known.
  • the earliest and simplest form of pressure relief device was simply to leave one of the sheet metal covers of the silo axis manholes unsecured so that when an over-pressurisation condition occurred the cover flapped open. This rudimentary measure was imprecise and prone to leakage due to damp ingress through the cover. In addition, the presence of unsecured covers on the roof of the silo was a potential safety risk.
  • a further known type of pressure relief device is known as a rising lid deadweight device.
  • the aperture is closed by a lid which may be lifted off its seat when an over-pressurisation condition occurs.
  • experiments have shown that such devices are incapable of responding quickly enough, and incapable of sustaining a sufficient flow capacity, in order to prevent the silo dangerously over-pressurising.
  • the lid is prone to jamming open on actuation leading to a continuing leakage of the silo contents into the environment.
  • the present invention therefore provides a pressure relief device for a silo comprising a body portion defining an aperture closable by a hinged lid the lid comprising a counterbalance, a pressure relief device for a silo comprising a body portion defining an aperture closable by a hinged lid, the lid comprising a counterbalance, wherein a centre of gravity of the counterbalance is aligned vertically with the pivot when the lid is in the closed position, such that the counterbalance applies no or a negligible torque about the pivot when the lid is in a closed position.
  • Figure 1 is a cross-sectional view through a pressure relief device according to the present invention.
  • Figure 2 is a plan view of the pressure relief device of Figure 1;
  • Figure 3 is a side view of the pressure relief device of Figure 1;
  • Figure 4 is a schematic representation of the pressure relief device of Figure 1 in a fully open position
  • Figure 5 is a schematic representation of the pressure relief device of Figure 1 in a closed position.
  • the pressure relief device 1 of the present invention comprises a cylindrical body 20 mounted to a base plate 25 and a lid 10 hinged to the cylindrical body 20 by means of a hinge 30.
  • the cylindrical body 20 is formed from a section of steel tube and for convenience is preferably formed from a standard size of tubing.
  • a lower end of the cylindrical body 20 is mounted to a base plate 25 by means of a fillet weld 24.
  • the base plate 25 is also preferably formed from steel and is used to mount the pressure relief device 1 to the silo 26.
  • the lower end of the cylindrical body 20 is open and in use communicates with the internal void space of the silo.
  • the upper end of the cylindrical body is open and is closeable in use by the lid 10.
  • An inwardly directed flange 21 is welded by means of a fillet weld 23 to the inner surface of the cylindrical body 20.
  • a cylindrical body 20 is formed from a section of steel tube and for convenience is preferably formed from a standard size of tubing.
  • a lower end of the cylindrical body 20 is mounted to a base plate 25 by means of a fillet weld 24.
  • the base plate 25 is also preferably formed from steel and is used
  • through-hole 22 is provided in the inwardly directed flange 21.
  • the lid 10 as shown in Figure 2, comprises a steel plate which has a ' D' shape having a substantially circular portion and a rectangular portion towards the hinged edge of the lid.
  • the 'D' shape of the lid 10 has the effect of altering the centre of gravity of the lid 10 to be nearer to the hinged edge than the centre of the pressure applied to the lid 10 in use which is centred on the circular portion of the lid 10 which is aligned with the cylindrical body 20. This has the effect of increasing the acceleration of opening of the lid 10.
  • the circular portion has an external diameter which is greater than the external diameter of the cylindrical body 20.
  • An annular gasket 11 is provided on a lower surface of the lid 10 and abuts in use against the upper rim of the cylindrical body 20 in order to provide a good seal therebetween.
  • the gasket 11 may be formed from any suitable rubberised or elastomeric compound.
  • the gasket 11 is preferably bonded to the lower surface of lid 10 by means of a glue or other adhesive.
  • An annular drip rim 12 is mounted to the periphery of the lid 10 on a lower edge thereof to depend downwardly therefrom.
  • the drip rim 12 serves to shield the annular gasket 11 and interface between the cylindrical body 20 and lid 10 from rain and water running off the upper surface of the lid 10 so as to prevent moisture ingress between the lid 10 and cylindrical body 20.
  • the drip rim 12 is preferably welded to lid 10.
  • the lid 10 further comprises an inwardly directed flange 15 welded by means of a fillet weld 17 to the lower surface of the lid 10 at or near the centre thereof.
  • the flange 15 is directed to be within the cylindrical body 20 when the pressure relief device is in the closed position as shown in Figure 1.
  • a through-hole 16 is provided in the flange 15.
  • a chain or other shackle (not shown) is strung between through-holes 16 and 22. The use of the chain will be described further below.
  • An upper surface of the lid 10 is provided with a threaded hole 13 at or near a centre thereof. The hole 13 may be used to secure additional ballast discs to the upper surface of the lid 10 if it is desired to increase the effective weight of the lid 10.
  • a section of tube 14 is mounted transversely by means of welding to the upper surface of lid 10.
  • the tube 14 allows for the insertion of a shaft or rod to allow a user to apply leverage to the lid 10 to aid the manual opening of the pressure relief device 1 during installation or maintenance.
  • Hinge 30 comprises two downwardly depending flanges 31 welded to the underside of the rectangular portion of the lid 10 and two outwardly extending flanges 32 which are mounted to the cylindrical body 20 by means of fillet welds 42 .
  • Both the downwardly depending flanges 31 and outwardly depending flanges 32 are rotatably mounted on a hinge pin 33 and are rotatable thereabout. End plates 34 are provided on hinge pin 33 so as to prevent hinge pin 33 being drawn out of the holes in the flanges 31 and 32.
  • an over-pressurisation of the silo will create an internal pressure in the silo which will create a force acting upwardly on the lower surface of lid 10.
  • a critical value known as the 'unstick' pressure
  • the force applied to the lower surface of the lid 10 is sufficient to unstick the lid 10 from the cylindrical body 20 and rotate it in an anti-clockwise direction when viewed as in Figure 1.
  • the unsticking of the lid 10 from the cylindrical body 20 allows the pressurised gas in the silo to rapidly vent to atmosphere.
  • the chain strung between holes 16 and 22 limits the angle ( ) of opening of the lid 10 to a predetermined value so as to avoid damage to the hinge 30 and to ensure that the lid 10 is capable of closing once the over-pressurisation has diminished.
  • the chain is 250 mm in length ensuring that the chain cannot become trapped between the lid 10 and the cylindrical body 20 as the lid 10 closes. This enables the designed maximum opening angle ⁇ to be achieved without risk of damage to the elastomeric seal, the sealing face of the cylindrical body 20 or to the chain itself. Oscillation and pressure pulsation problems can occur with pressure relief devices having a hinged lid since once the lid is open the airflow through the device decays as the pressure in the silo diminishes .
  • a counterbalance in the form of a weight 40 is mounted by means of a fillet weld 41 to the upper surface of lid 10 and positioned such that the centre of gravity of the counterbalance 40 lies vertically above the centre of rotation of hinge pin 33 as shown in Figure 1 so that the counterbalance 40 exerts no torque about the pivot in the closed position of lid 10.
  • the weight of the counterbalance 40 is directed vertically through the pivot point and is supported directly by the hinge pin 33 it has little or no effect on the static sealing load of the lid 10.
  • the maximum angle . of lid inclination is chosen to be in the range of 50 to 60 degrees. More preferably, the maximum angle is 55 degrees to generate a sufficient moment to initiate lid closure and to overcome windage effects on the open lid.
  • the centre of gravity of the counterbalance 40 moves out of alignment with the axis of rotation of hinge pin 33. Consequently, the counterbalance 40 applies a torque to the lid 10 tending to urge the lid 10 to open. As such, this assists the opening of the lid 10 and increases the acceleration of the lid 10.
  • the torque applied increases progressively as the opening angle . increases and is a maximum at the point of maximum lid inclination. At this point, it is preferable that the torque applied by the counterbalance 40 cancels out the majority of the torque generated in the reverse direction by the mass of the lid 10.
  • the lid 10 does not start to close until the air flow through the pressure relief device 1 is commensurately lower the degree of oscillation of the lid 10 and its associated pressure pulsation within the silo is significantly reduced.
  • the mass and location of the counterbalance 40 will vary depending on the mass of the lid 10, the chosen maximum opening angle . and the chosen unsticking pressure.
  • the following example is therefore exemplary in nature and is based on adapting the a pressure relief device which has an effective area of 61 300 mm 2 (95 in 2 ) .
  • the unstick pressure must be sufficiently above the normal working pressures of the silo, 1.03-1.38 KN/m 2 (0.15-0.20 psig) , so as to prevent unwanted openings of the device in non-overpressurisation conditions and also sufficiently below the pressure rating of the silo, 6.90 KN/m 2 (1.0 psig), to allow for an adequate safety margin.
  • a minimum acceleration of the lid may be calculated which must be met in order to meet the pressurisation requirements. The minimum acceleration may be calculated by assuming that the maximum permitted pressurisation of 6.9 KN/m/m (1 psig) is acting on the lid.
  • the maximum residual force available to accelerate the lid to fully open is the total available force less the weight of the lid. (In practice the residual force will increase from zero at the point of unsticking to the maximum residual force at 6.9 KN/m/m (1 psig) . However, this occurs so rapidly that for these calculations it has been assumed that 6.9 KN/m/m (1 psig) acts throughout) . As mentioned above the weight of the lid 10 is 29.94 kg (66 lbs). Thus, the residual force equals:
  • the minimum acceleration equals: .
  • the equivalent pressure relief device according to the present invention having an effective area of 61 300 mm 2 (95 in 2 ) requires a lid acceleration no less than 4.31 m/s/s to prevent the pressure in the silo exceeding 6.90 KN/m 2 .
  • the addition of the counterbalance 40 increases the inertia of the lid which requires a reduction in the mass of the lid.
  • Maximum lid inclination, is chosen as 55 degrees.
  • the inertia of the lid 10 acts vertically down through the centre of gravity of the lid 10 and equals the weight of the lid:
  • the counterbalanced lid of the present invention opens 29% faster than the non- counterbalanced pressure relief device lid.
  • the counterbalanced lid has the advantage that the faster opening of the lid will enable the lid to reach its fully open position more quickly enabling the device to better handle the initial maximum pressure within the silo and the flowrate transient.
  • the counterbalancing (88%) in the fully open position increases the lid dwell time in the fully open position which increases the overall venting capacity of the device and shortens the venting cycle. oscillations and pressure pulsation are also significantly reduced if not eliminated.
  • the device may be manufactured wholly from standard plate and tube sizes from steel.
  • the device may also be easily retro-fitted to existing silos since the external shape and dimensions of the cylindrical body have not been changed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Pressure Vessels And Lids Thereof (AREA)

Abstract

La présente invention concerne un dispositif de décompression pour un silo. Ce dispositif comprend une partie de corps (20) définissant une ouverture pouvant être fermée par un couvercle articulé (10). Ce couvercle comprend un contrepoids (40) selon lequel le centre de gravité du contrepoids (40) est aligné dans le sens vertical par rapport au pivot lorsque le couvercle est en position fermée, de telle sorte que le contrepoids (40) n'applique aucun couple ou un couple non significatif autour du pivot lorsque le couvercle est en position fermée.
PCT/GB2003/000606 2002-02-18 2003-02-11 Dispositif de decompression pour silos WO2003068634A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003245770A AU2003245770A1 (en) 2002-02-18 2003-02-11 Pressure relief device for silos

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0203787A GB2385407B (en) 2002-02-18 2002-02-18 Pressure relief device
GB0203787.7 2002-02-18

Publications (1)

Publication Number Publication Date
WO2003068634A1 true WO2003068634A1 (fr) 2003-08-21

Family

ID=9931279

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2003/000606 WO2003068634A1 (fr) 2002-02-18 2003-02-11 Dispositif de decompression pour silos

Country Status (3)

Country Link
AU (1) AU2003245770A1 (fr)
GB (1) GB2385407B (fr)
WO (1) WO2003068634A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8608021B2 (en) 2008-02-22 2013-12-17 Mechtronic Limited Road tanker fluid storage tank fill cover assembly
CN104632041A (zh) * 2014-12-17 2015-05-20 安徽博微长安电子有限公司 一种粮库用通风口密封保温门

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4052108A (en) * 1975-10-09 1977-10-04 Weaver Richard L Filling system for a silo
DE3414827A1 (de) * 1984-04-19 1985-10-31 Heinz 7129 Zaberfeld Bissinger Silobehaelter
US5141020A (en) * 1991-09-30 1992-08-25 Dover Corporation Emergency vent valves for storage tanks
DE19711208A1 (de) * 1997-03-18 1998-09-24 Rudolf Hajek Druckentlastungsklappe
US6003705A (en) * 1998-05-19 1999-12-21 Magnum Mud Equipment Company Portable bulk storage container having and easy opening lid

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3667260A (en) * 1971-01-25 1972-06-06 Master Lock Co Exhaust pipe protector lock
DD146762A3 (de) * 1977-06-30 1981-03-04 Christian Trautmann Abdeckeinrichtung fuer behaelter,oeffnungen und dergleichen,insbesondere kochkessel
US4182459A (en) * 1979-03-29 1980-01-08 Williams Clarence E Safety receptacle
GB2167545A (en) * 1984-11-27 1986-05-29 Nrg Systems Inc Flue assembly
JPH04109024A (ja) * 1990-08-27 1992-04-10 Mitsubishi Electric Corp 排気装置
US5205311A (en) * 1992-03-06 1993-04-27 Electromechanical Research Laboratories, Inc. Compound lever controlled spill valve
JP2938409B2 (ja) * 1997-09-01 1999-08-23 東京急行電鉄株式会社 踏切制御装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4052108A (en) * 1975-10-09 1977-10-04 Weaver Richard L Filling system for a silo
DE3414827A1 (de) * 1984-04-19 1985-10-31 Heinz 7129 Zaberfeld Bissinger Silobehaelter
US5141020A (en) * 1991-09-30 1992-08-25 Dover Corporation Emergency vent valves for storage tanks
DE19711208A1 (de) * 1997-03-18 1998-09-24 Rudolf Hajek Druckentlastungsklappe
US6003705A (en) * 1998-05-19 1999-12-21 Magnum Mud Equipment Company Portable bulk storage container having and easy opening lid

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8608021B2 (en) 2008-02-22 2013-12-17 Mechtronic Limited Road tanker fluid storage tank fill cover assembly
EP2254771B2 (fr) † 2008-02-22 2015-01-21 Mechtronic Ltd. Ensemble couvercle de remplissage de cuve de stockage de fluide pour camion-citerne
CN104632041A (zh) * 2014-12-17 2015-05-20 安徽博微长安电子有限公司 一种粮库用通风口密封保温门

Also Published As

Publication number Publication date
GB2385407A (en) 2003-08-20
GB0203787D0 (en) 2002-04-03
GB2385407B (en) 2004-04-14
AU2003245770A1 (en) 2003-09-04

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