GB2217427A

GB2217427A - Settling or compacting granular material

Info

Publication number: GB2217427A
Application number: GB8906339A
Authority: GB
Inventors: Neil Currie
Original assignee: CHEMROCK CRYOGENIC CORP
Current assignee: CHEMROCK CRYOGENIC CORP
Priority date: 1988-03-26
Filing date: 1989-03-20
Publication date: 1989-10-25
Anticipated expiration: 2009-03-20
Also published as: GB8807276D0; GB8906339D0; MY104414A; GB2217427B; EP0339785A1

Abstract

A method of compacting granular insulating material in an enclosed space particularly in the annular space between an inner shell and an outer wall of a storage tank utilises an apparatus comprising a carrier (15), means (19) for moving the carrier (15) around the space and for varying the height of the carrier within the space, and a plurality of elongated pokers (22) supported by and depending from the carrier (15). The method comprises periodically lowering the carrier (15) to immerse the pokers (22) into the granular material and then raising the carrier (15) to withdraw the pokers (22) from the granular material and periodically moving the carrier (15) to different positions with the pokers (22) withdrawn from the granular material. The pokers (22) are vibrated relatively to the carrier (15). <IMAGE>

Description

Settling or Compacting Granular Material T is ") 'I c- L 17 4 27 0 This

ir-,,en:.or. to a)T)arat-us and -,n-,-:1:,ods f r settling or compactinz gran-ular material contained in an enclosed sDace. More parzicularly, but. not exclusivel-7, the invention is concerned with settling or compactinc granular insulating in r-he annular space between the inner and outer walls of larQe storaQe tanks such as are fied natural gas (7 used for the storace of lic;u -NG) and ozoer 1-c.---,'--Fied cases.

trend in --he s.:oraae of liquified gases has inoved inc--ea--incl7 z--use of tankswi-,- concrete outer shells. in l-nos-= tanks usinc perilte insula.:on in the annular space the:o co-.,:5acz the perlize durinc placing is considered zo be- imperative because:- a) the design detail;e±ween the wall and roof of the tanks leaves little he-ic:'-)-for a reservoir of perlite to be provided and whic.- moves down into the annular space to allow for natural compaction and filling of the void left after cool down of the inner tank. In existing tank designs the total drop in insulation level in the annular space fro-.-,i these two factors can be more than 3.5 metres.

b) due to the poten.:ial hazards in topping up tanks in service great care has to be taken with regard to the d use of an inert cas as a propellant, and also to avoid build up of stt- a:-ic electrical charge; the work is comparatively slc-..; and also more expensive per cubic metre filled than the cost of the initial filing.

I- 'a', is 1 "- = In Australian Patent desir-=b4-' Jzy of set-.li---. tthe granular insulazing maz;-=r---zl is d i s c u S S e ed and al so t- e p r Ob- 'L e m s W_--- satisfactorily carryinc: ou-L rthe s=--:z-l-ina process.

-he ou-ter wall of e tank is mets! Where 't k_.. - convent-tonall system, for setzi-ing the insulating materiall to apply vibrators t_l the outs--de of t h e= ou-.er she 1 Conven-tional vibrator system, can not, be used on concreze outer shells 0.5-1.0 me.:res ri-nick, neit.her can they b-e used. e.Ifeci-.,:-=!v on the inner tanks, due to the v-4ora--ion Of the blankee f f e- c t w c- n o --m a l 1 v s. 1 r r o u n th inner s--ell and s-aiDar-=:es granular from the inner shell.

zion problems proposed solu aforesaid Australian;--.pqliica-_ion is to posirion a - - metal plate so that it is at least parttiallv immersed in the granular material in the space and then to vibrate the --la7::e 7ect L to ef-L' L. settling.

In present day methods the expanded pe-r-1-J-e _J s produced on site from perlite ore and ideally the filling and compaction operations should at least keep pace with the -he end of the expanded perlite production rate. Also at t operation the apparatus should be reasonably easily removable from the annular soace between the inner shell and 25 - invention to outer wall. It is the object of the present provide such a method and apparatus.

Accordinc[ to one aspect of t.ne invention an apparatus for settling or compacting granular material contained in an enclosed space comprises a carrier, means 2 - t.- r.

t Ar for moving the so that i 7 can be locai:ed a -i - positions il- t.le space, a plura--,i---- dij':jcerenl enclos;-=-elongated pokers su-uor:ed by and depending f-rom the so that they can be inserted into tne granular material,' for producing a settling or compacting effect. on tne granular material, by positioning of the carrier above the material.

The material important providinc strength to perform, t-ask.

The pokers are advantaceousiv arranced o - - - b, z vibrated rela-tivel-,., z::'.ie carrier zy one or micre Thus the pokers may be arranged in -roups eacn can--ed wi--'vibrator. All,--e--naz--.je-'. -., each of t-=- pokers has a vibrator associated wiz- it for ca--sinc bodil-i vibr-=-z-ion of -ive L-he poker relat to the carrier. Advantageously vibrator is housed within the associated eoker. The vibrators may be electrically, pneumatically or even accoustically operated. The advantage of using the plurality of vibrating pokers in an annular space is that the pokers can be disposed widthwise as well as circumferentially so that there is a large vibrating area within the granular material and all the granular material is closer to a vibrating surface as compared with a vibrating plate.

The pokers may be of any cross-sectional shape.

howeve.r they are selected to produce a wedging effect when inserted into the granular material.

Preferably, at least a lower part of each poker, i.e. the part designed to extend into the granular material from which the nokers are formed is no7:

that the poke-rs have the necessa----- Advantageously 3 - is ta-e-ed for exam-1= conical'17 SO tha- it is off. dec-r--las,,-,- :1 - t- - - cross-section as one proceeds downwardly over said 1 az part z 0 1 S lower end in order to minimise t -, e drresi-czance as the poker is pulled ouz of the 9-,--:-nul-=-ma-----'al. Thus the poker may taper downwardly over i---z Tn whole lengt-.- or only over a lower part of its length.

the latter case the poker may also taper over an upper iDar-- L 0 'L izs length so t'-az its cross-section also decreases ui:)wa--d'-,, from said junction with said lower part. S h o u the poker then sink 'Loo deeply into the material so tha the u.o,je-- par-- becomes Par--!y immersed in the granular mate-rial, he drag rezicz;znc= when pulling the poker ou- c-z I = o-ar..--r mazerial is reduced as comnared with a i)oker Lhavinc one conzinuous taiDer o-er its whole length. Thus eac.t- of t-e-, is E pokers may be of double conical form with the bases o'L --'- e cones conjoined.

The pokers may be arranged in a plurality of adjacent rows with the pokers in one row staggered in posi::ion along the row with respect to the pokers in another row.

According to another aspect of the invention, there is provided a method of compacting granular insulating material in the annular space between an inner shell and an outer wall of a storage tank utilising an apparatu- s comprising a carrier, means for moving the carrier around the annular space and for varying the height of the carrier within the annular space, and a plurality of elonga:e--' pokers supported by and depending from, the carri.er, th'-Z method comprising carrying out a cycle of operations 4 a b consistina of lower-inc: the carrier to immerse t--- i:)okers into the granular material for effecting a seztl-'Lnc or -ing of the granj.1ar material, raising the carrier -c con, iDact w-4.:'r,draw ti-le pokers from, the granular material and - iovin,::

-h the pokers the carrier around --he annular space wit withdrawn from the granular material and tnen repeating the cycle a plu-ralitv of ti-mes.

Thus aranular material is fed into the annular space, a plurality of said cycles of operation carried out --- e c-arrier, further granular materiall at a firs- level of z,, --ion added in stages and a::,luralL-y of said cycles of operat ions carried out at increasingly highe: levels between addJt. of granular material.

Preferably the pokers are individually v-Lbra--ed at least when thev are immersed in the granular material.

Preferably the pokers are disposed on the carrier so that they extend in at least two rows spaced from each other across the width of the annular space the pokers in each row extending around the annular space.

The invention will now be described by way of example with reference to the accompanying drawing, in which:

Figure 1 shows a front elevational view of one form of apparatus for carrying the invention into effect, Figure 2 shows a cross-section through the upper wall structure of a storage tank with the apparatus in position.

Figure 3 shows a plan view of the apparatus, Figure 4 shows an elevational view of a detail, and Ficure 5 shows a seciion on the line V-v off Ficure 1C, Referring now to the drawings, t-e tank is 1 conventional desiqn a--2 has an inner cyLir.--7_-ic-=! she metal whose outer su---=ace is shown at 10 (Fig.2) and outer cylindrical conc-rete wall wnose inner surface is shown at 11 (Fic.2) and whic- may be up to 1 me-__-e thick.

-hem, an annular space 1,2.

surfaces 10 and 11 define be--ween t The inner shell is su----,Dunded by a resilienz blanket 13 of, for example, resilien-- glassfibre and the surface 11 of the oiter wall --=v be lined, with an insulation laver 27 of, for exam-ole, -zolyure --nane. The rem-ain'-15ef of tne annular s-cace is f4 Ll-ed with compacted perlite. n -. n e drawing the perlite iS shown as having been placed, up to, level 14. Such a bl-;=:,,Ket 13 is necessary because perlize when compacted is vir--ually non-compressible. The blanke:

13 acts as a cushion to absorb relative movemient of the tank walls and thereby substantially eliminate crushing of the perlite after the placing and compacting of the perlite has been completed.

The insulating perlite material is supplied to the annular space 12 between the walls 10 and 11 through a series of filling ports (not shown) distributed around the top of the tank.

In order to settle and compact the perlite an apparatus 15 is provided which is suspended on cables chains 16 from hoists 17. The hoists 17 form part of a cat structure 19 which is mounted on crane beam 18 secured in the annular space 12. The beam 18 extends a--out the annular io - 6 0- v j r space 12 over the com-Dlet-e circul ar extent of the annular space 12. The can sz-zructure 19 can be driven along t..crane beam 18 in the:7, anner of a cantry crane -so that i': c-=n do a complete journey -around the annular space 12. The cac structure 19 also has an o-erator's control console 20.

-us "5 comorises a framework 21 from whic- The aL---aral I J pckers 22.

depend a series of The framework 21 which iz! -angular in plan vie--.4 is in two part Ila generally recT L-s 2 and 7 -o e c. other 21b which can be angularly adjusted relatiVel 1. a h so that, within limii:S, the appar-azus 15 can be accommodated in annular soaces of -- ifferent curvatures fro,-,i each other.

The pokers 22 are of dou---I-- conical for.n comprisina lower cone 23 and upper cone 24- conjoined att their bases. In this example as can oe seen in Fig.3 two pokers 22 are disposed across the width of the annular space 12 and theree may be, for example, six pokers in all disposed in two rows of three with the pokers 22 in one row staggered with - to the pokers 22 in the other row.

resiDect The lower cone 23 of each poker 22 carries within it -ing eccentric weight type.The a vibrator 31 of the rotat I lower cone 23 is typically 6" in diameter at its base.and is about 4 feet in length base to apex. The base of the upper cone 24 extends upwardly from the base of the lower cone 23 - plates 25 through resilient and is secured to gusset suspension means in the form of rubber pads 32. The gusset plates are themselves secured to 'the framework 21.

To constrain and guide the framework 21 around the annular space 12, SOLbrushes 26 are provided on its inner and Outer sides and which engage the insulating blanket 12 - 7 cu and the outer wall ---face1-1 and anv insulation layer 7 respectively. Alternatively other devices may be 1 f soft brushes, for exam,D-ie a rubber bu-oer. inszead of 4 In order to D!;-mce and compact perlite in the annular -0 laver cl --ially a fi-s' space 12 using the appara--us 1 init perlite is L-ro,T.ded az the bottom of annular siDace 12 and' the iDokers are inserted into it at a first position to a de]D-L.;.] of say 3-4 feet. The perlite is compaczed by the vibration of the -ooke--s 22.

After a predetermined time the pokers 22 are hoiste---- out of the -oerlli-e and moved a prede±----.-nined d--zzance around the annular space 12 and then re-inserzed into lk- he insulatina mazerial a:: a second position. This is repeated until a comple.:e travel of the annular space has been effected L-ne appara-tuss 15.Then the alDiDaratus 15 is raised to a higher level andthe sequence of oneration is repeated on a fresh layer of perlite material. The apparatus 15 is successively raised to higher levels in this way until the annular space 12 has been filled to the desired height with compacted perlite.

The aggregate volume of the lower cones 23 should advantageously approximate to the anticipated decrease in volume of the perlite resulting from the induced settlement.

If it is assumed by way of a typical example that in order to keep pace with the on-site production of expanded perlite, the distance round the annular space to be covered is 60 metres per hour, then assuming each v---- operation lasts 6 minutes, there are ten moves per hour so Q that each move around the annular s.Dace be-tween each vibration opera-lion would be 6 metres.

Consequently in 8 order to cover the whole of the annular spacce w-L.::ioutt significant spaces the pokers 22 should extend over an of the order of 6 mezres.

Alternatively, there may be more than one of the apparatus 15 dispos,-:-., --- around the annular sTDace and workine simultaneously either 'to reduce the extent of the arc over which the pokers 22.2 of each apparatus 15 extend or to keen up with perlite production.

After comiDlezion of the compaction up to the desired height the appar-atu-s 15 is sufficien-L1V small thaz iz can be readily removed through one of the manhole openings in the roof of the tank.

The advant-ae a -- c of the above described des-Lcn of apparat-us over the use of apparatus using fl-=-- or curved - have a tendencv zo "Plane" in plates, is thaz it does not the perlite and change direction like the latter, possibly causing damage to the blanket 12 and the liner 27.

9

Claims

CLAIMS is - ing granular 1 Apparatus for settlina or compact material

contained in an enclosed space comprising a carrier, means for moving the carrier so thall- it can be located at different positions in the enclosed space, a plurality of elongated pokers supported by and depending from the carrier so that they can be inserted into the granular material, for producing a settling or compacting effect on the granular material, by positioning of the carrier above the granular material.
2. Apparatus according to cla Lm 1, wherein the pokers are arranged to be vi-c-rated relatively to the carrier by one or more vibrators.

AiDiDaralt--us as claimed in claim 1, wherein the pokerS
3. M_ are arranged in gro..,ios, each group being arranged t o b vibrated by a respective vibrator.
4. Apparatus according to claim 2 wherein each of the pokers has a respective vibrator associated with it for --ion of the poker relative to the causing bodily vibrall carrier.
5. Apparatus according to claim 4, wherein each of the pokers houses the associated vibrator within it.
6. Apparatus according to any preceding claim, wherein each of the pokers is tapered at least over a lower part of its length so that it has a decreasing cross-section proceeding downwardly over said lower part to its lower end.
7. Apparatus according to claim 6, wherein each of said pokers is conical over at least said lower part.
8. Apparatus according to any one of claims 1 to 5, - c -v 1 wherein each of said pokers is tapered over a lower part of its length so that it has a decreasing cross-section proceeding downwardly over said lower part to its lower enc- - h f r o.-..

and is also tapered over an upper part of its lenqt wi-h said lower part so that its cross-section the junct also decreases upwardly from said junction.
9. Apparatus according to claim 8, wherein each of tne pokers is of double conical form with the bases of the cones conjoined.
10. Apparatus according to any preceding claim, wherein the -Pokers are arranged in a plurality of sideby-side rows with the pokers in one row staggered in position along th,e row with respect to the pokers in another row.
11. A method of compacting granular insulating material in the annular space between an inner shell and an outer wall of a storage tank utilising an apparatus comprising a carrier, means for moving the carrier around the annular space and for varying the height of the carrier within the annular space, and a plurality of elongated pokers supported by and depending from the carrier, the method comprising carrying out a cycle of operations consisting of lowering the carrier to immerse the pokers into the granular material for effecting a settling or compacting of the granular material, raising the carrier to withdraw the pokers from, the granular material and moving the carrier around the annular space with the pokers withdrawn from the granular material and then repeating the cycle a plurality of times.
12. A method according to claim 11, wherein in a cycle of operation of the apparatus granular material is fed into t the annular space, a plurality of said cycles of operation carried out a-- a first level of the carrier, f u r th e r 1 added in stages and a plurali-v of said' granular materiaL cycles of operation carried out at increasingly higher levels between additions of granular material.
13. A method according to claim 11 or 12 wherein the pokers are individually vibrated at least when they are immersed in the granular material.
14. A met-hod according to any one of claims 11, to 13, wherein the pokers are disposed on the carrier so that the,; extend in atleast. two rows soaced from each other across the width of the annular space the pokers in e-ach row etending around the annular space.
xt is. A method according to any one of claims!-! to la-, wherein each poker is tapered az least over a lower part so that it has a decreasing cross-section proceeding downwardll over said lower part to its lower end, and the height of said carrier is so controlled that the pokers normally only become immersed in the granular material over their tapered part.
16. A method according to any one of claims 11 to 14, wherein each poker is tapered over a lower part so that it has a decreasing cross-section proceeding downwardly over said lower part to its lower end and is also tapered over an upper part of its length from the junction with said lower part so that its crosssection also decreases upwardly from said junction, and the height of said carrier is so controlled that the pokers normally only become immersed in the granular material over their lower tapered part.
17. A method according to any of claims 1-1 to 16, wherein the carrier is suspended by cables from a hoisz which runs around the annular space and the movement of the carrier around the annular space is guided by brushes which are mounted on the carrier of the inner shell and the of the storage tank.
18. Apparatus for settling or compacting granular material substantiall-7 as hereinbefore described with reference to the accompanying drawings.
19. A method of settling or compacting granular material substantially as hereinbefore described.' and engage the external surface inner surface of the outer wall - 13 Published 1989atThePatent Office. State Houne,667,!High Holborn, LoixdonWCIR4TP, Further copies maybe obtained from The Patent Office. Sales Branch, St Mary Cray. Orpirgton, Kent BR5 3RD. Printed by Multiplex tecb.Tnques ltd. St Mary Cray, Kent, Con. 1/87