CA2117206A1 - Process and apparatus for cryogenically cleaning residue from containers and reducing the bulk volume thereof - Google Patents

Abstract

A method and apparatus for the cleaning of residue from the surface of a container where the method comprises cooling a container and residue adhered to the container surface to a low temperature, substantially embrittling the residue and then impacting the container to fragment and separate the residue from the surface of the container. The cooling may be effected by contacting cold vaporized cryogen to the residue and container in an insulated box having a cryogen sprayer, an opening, and a door. A method for reducing the bulk volumes of containers comprising cooling the container to a low temperature to substantially embrittle the container and then stressing the container to fracture and break apart the embrittled portions and thereby reduce the bulk column of the container.

Description

P~OCE~S A~D APPARATUS FOR CRYO~ENICALLY
C~EANIN~ RES~UE FROM
CG~T~I~ERS AN~ RE~CING THE BUL~ VOLU~E ~HE~EO~

lC ~A~GROUND GF T~E lNV~TION
The pr2sent inventio~ generally relates to the removal of residual mate~ials fro~ con~iners ~o~
disposal or ~ecycling. More specific211y, the pre~en~
inven~ion relat~s to a method and ~pp~ratus ~or cleaning residues froffl the surface o~ c~ntainers ~y ~he use of low tempe~at~res. In addition, the preserlt invention ~el~tes to a me~hod and apparatus for ~educing the bulk volume of ~ontainers by the use of low temperatures.
The disposal of wastes has become a great concern due to the environ~ental problems associated with hazardous materials. Of even more immedia~e conce~n are the economic problems associated with rising costs and reduced capacit~ of lan~fills, as well as the tighter governmental regulat~ons facin~ waste gene~ors. Consequently, disposal of containers and the residual materials re~aining there~n can be a cos~ly and time consuming endeavor. Emphasis has been placed on cleanin~ the residues fro~ the ~ontainers so that only ~he residues, and not the containers, a~e su~jec~ to ~ostly h~z~rdous was~e disposal. This le~ves the con~ainers available ~o be re~sed, recycled, or disposed of in a less expensive non-haza~dous waste landfill.

2 --The ~.S. govern~ent has esta~lished ~uidelines under the ~esource Con~ervation and Recovery ~ct (P~CRA) th~t specir~y t}le c:leanliness requirements for disposal of containers as non-hazardous w~ste.
Ne~erthelQss, some states are imposing ~ans on the disposal o even clean containers in lan~fill~ as a remedy ~or rapidly diminishing landfill capacity. This le~ves ~euse or reoycling of the con~a~ne~s as the only alternative.
A broad range of ~esi~ue materials are subject to costly h~z~rdous was~e disposal. So~e of these residues include, ~t are ~ot limited to tars, l~ricants, mastics, inks, coatings, solvents, ~hesi~es, sealant--, paints, e~c. A ranqe o~
1~ traditional cleaning ~ethods exists to remove suoh residues from cont~iners. These methods include applying water, s~eam, soaps, deter~ents, chemi~l solvents, ~brasi~es and scrubbing equipment. All of these metAods result in an in~reased volume o~ waste being cre~ted th~t m~y be more diffi~ult to dispose o~
than the original recidue. These met~o~s may be costly ~ue to the need of expehsive materials, equipment and intensive labor. ~Yen if the residue is not considered haz~rdous, there may be restr~ction~ imposed by muni~ipal sewage districts that require expensive pre-~reatment before the residue and w~sh liquid may be disch~rged into the sew~e drains.
As an exa~ple of traditional cleaning ~e~hods, chemi~al solvent based cleaning invol~es numerous disadvan~ages. The sol~ents are expensive.
They ~equire special ~are and handling bec~use of their co~bustibili~y, corrosiveness and/or volatility.
Special ventilation equip~ent may ~e required ~o recover the volatile organic co-mpounds which vaporize dur~ng use. Additional equipment may be n~eded ~o separate the solvent from the residue waste w~sh for recycling of ~he ~olven~. If not separated, the volume of the waste pro~uc~ is gre~tly ~n~reased. Employees require additional training to ~a~ely handle the e~uipment and m~erials. Speci~l inspections, building c~des and zoning requi~ements may be ~if~icult to c~mply with, or require ~nat special facilities be constructe~ for ~he cle~ning equipment. In the end, most small o~g~nization~ do not h~ve the resou~es ~o properly handle the problems associated with disposing 1~ or recycling residue laden con~ainers ~sing traditional methods.
Even when the containers ~re cle~n, the sheer bulk ~olu~e ~ ~he containers may ma~e ~heir di~posal or recycling p~o~lematic. Storage and transportation lS costs are related to the b~k ~o~ume of ~he ~reight.
Apparatus exl~t~ ~or the si2e ~eduction, This e~uipment is available for application t~ reduce the bulX ~olume of cont2iners. However, this equipmen~ is not without certain disadv~nta~es.
Typically, the bulk volume o~ plastic containers is reduced ~y shredding the containers.
Shredding equip~ent may be highly dangerous to operate, expo~ing personnel to se~e~e ~jury if improperly used.
The m~chinery may also be ve~y expensi~e and require significant mainten~nce.
On the other hand, the bulk volume of metal cont~iners is commonly red~ced ~y compacting or crushing. This equipment m~y be less expensive than ~h~edding machinery and safer to operate. The equlpment applie~ a compres~ive force to cru~h and pexmanently de~orm the met~ ~ontaine~s.
Unfortunately, compactin~ equipment designed to crush met~l cont~iners m~y n~t work satisfactorily with plas~ic containers having ~ ~egree of elasticity.
Gener~lly, plastic containers have a tenden~y to partially rebound to their origihal shape after the compressive ~orces are ~ele~sed. When a plastic container is removed from the compac~or, it wo~ld return to near its original bulk volu~e.
Therefor~ r ~he foregoing ~easons, there is a need fo~ a ~e~hod and or ~pparatus for treatin~
plastic containers so that ~hey maint~in a reduced bulk volume af~er release of compression forces that is safe, ~imple ~nd co t efeotive.
In a~dition, there exist~ a sizable gap between existing traditional cleanlng methods to remove resi~ue from containers and the req~irements of industry to ~lean con~ainers with a cost effec~ive, environmentally safe process. The~efore, there exists the need for a method and apparatus for cleaning residues from containers that does no~ have the inefficiencies, hazards an~ en~ironmentat liabili~ies associated with traditional cleaning ~etho~s.

SUMMARY OF T~E INVENTION
Accordingly, ~he present invention is directed to provide a simp~e, cost effective, environmen~ally s~fe met~od and apparatus ~or the cleaning of residues from the surfaces o~ cont~iners.
In ah aspect of ~he invention, the method involves cooling ~ re~idue l~den container to a t~perature where the resid~e becomes em~rit~led ~nd then impacting th~ ~ont~ine~ to cause tne residue ~o fragment and separate from ~he con~ainer. Prefer~bly, the container is cooled by placing it in an insulated box ~nd contacti~g it with ~ ~old cryogenic ~rapor.
Another aspect o~ the invention pro~ es ~
~fe, s7mple~ cost ef~ective method and apparatus for the tre~t~ ng of ~ co~tainer to reduce its bulk volume.
In p~rti~ular, the met~od involves cooling a ~ontainer to a tempera~ure ~here ~he con~aine~ becomes em~rittled and then applying forces ~c) f r~gment and ~reak apart _ - 5 -the cont~iner, thereby, per~anently reducin~ its bulk volume. Preferably, the cont~iner is cooled by placing it in an insul~ted ~ox and contacting it with cold cryogenic vap~r.
The p~efer~ed embodi~nts of the in~ention avoid the use of solven~s and other wa~h liquids so that the hazardo~s material for dispos~1 is limi~ed to ~he original residue itse~f. These embodiments also re~ire le~s equip~ent and less labor to operate than tra~itional method~ of cleaning and reduces health risks to the oper~ting personnel. The pxeferred em~odiments substantially remove the resid~es from the container to meet U.S. government disposal ~equire~ents ~nd in~u~try require~.ents fo~ re-use o~ the co~t~iner.
In a~dition, the preferred embodiment of the invention allows plastic containers to be reduced in ~ulk ~olume using tradi~ional equip~ent designed for me~ ontaine~s, The present invention may also per~it the crushing of meta~ containers with less force than would normally be required. Further advantages of the present invention will ~e apparen~ ~rom the a~companying drawings and ~he det~iled descrip~ion of the invention.

2 5 BRIE~ 8CRIPTION OF T~E ~ IN~;S
FIGU~E 1 is a perspective view of ohe embo~imen~ of the apparatus of t~e present invention inc:l~ding an insulated ~ox h~ving a side opening.
FIGURE 2 is an enl~rged perspective view of the appa~atus o~ Fi~ure 1 showing the interconnecting hose ~e~ai L .
~IG~E 3 is a perspective view of the interior of the insulated box of Figure 1.
FIGURE 4 is a ~ide cross-sectional view of the insul~ed box of Figure 1.

2~I 72~

FIGU~E 5 is an en~arged side cross-~ectional view taken alony line 5-5 of Figure 2 showLn~ the detail of the vent port.
F~GURE 5 i~ a pe~spective view of one embod~-ment of a preferred receptacle cover in opera~ion witha residue receptacle, an imp~cting device and a container.
FIG~RE 7 is an exploded p~r~pective view of the receptacle cove~ o~ Figure 6.
~O FIGUR~ 8 LS a perspective view of a second embodi~ent o~ the ~ppa~atus of the present invention including an insuldte~ ~ox havin~ a top opening.
FIGURE 3 is a perspective ~iew o~ another embodiment of an impacting device in oper~tion with the }5 preferred recept~cle coYer of Figure 5.
FIGURE 10 is an enlarged oross-sectional view ta~en ~l~ng line 10-10 of ~lgure 1 showing the detail of the gasket.
~IGrJ~ ll is an enl~ged cross-sec-'iGnal view taken along line 11-ll of Figure 8 showing the detail of the qasket.

DETAI~ED ~SCRIP~}ON OF ~E DRAWIN~
AND P~ESENTLY PREFE~RE~ EMBODr~ENTS
A prefer~ed em~odiment of the system used to cryogenically clean residue fro~ a container i~
deplCted ih ~igu~ec 1 thr~gh ~. The system co~prlses an insula~ed box 10, a liq~id o~yogen storage tank 12, interconne~ting cryogen hose 14, an impacting device (~IG.6) and ~ residue recep~acle l~ (~IG~ 6).
As ~hown in ~igure~ ~ ~hrough 5, a preferred embodimen~ of the insul~ted ~ox 10 includes a pivotably mounted doo~ 18 covering an openin~ ~ located on the f~ont side of the box 10, a t~perature gauge 2 6, a 3S vent port 30, ~nd two c~yogen sprayers 38 and 53.

As most easily seen in Figure 4, the insulated hox 10 i~ made of interior w~lls 3~ and exte~ior walls 34 with a l~ye~ of in~ul~tioh 33 ~etween the walls. The interio~ and ex~eri o~ wal~s 35 and 34 ~a~ be made of a ~ariety of ~-ommercially ~ailable d~able materials, such ~s, but not limited to, mild steel, alu~inum, stainless s~eel or galvani2ed stee~.
Likew~se, the insulation 33 may be a vari~ty of commercially ~vail~ble materi~ls su~h as, but not 10 ~ i~ited to, ~iberg~ss or expanded polystyrene. ~he hox 10 has a back wall So, two opposing side walls 35, ~ op wall 37, a boltom wall 49 and a fron~ side opening 22.
As shown in ~ig~ure l, the door 18 has a h~ndle 23, latches 24 and a sas spring 20. The door 18 is pivotably mounted on hinges connected to a ~ide wall 36 opposite the hand~e 23. The g~s sp~ing 20 movably connects the top or the door 1~ to the top of the box lO suGh th~t ~he ga~ spring 20 pull~ the door 18 ~o a clo~ed position. As ~escribed in ~etail below, the door 1~ and walls of the box 10 nave gaskets 75 and 75 (described in detail helow and shown in Fiq. 10) placed along tne perimeter to seal the box 10 when door 18 is closed.
The box 10 ~lso includes two fork iift pockets 48 along the botto~ wall 49 to assist in . ~ransport of the box lO ~y fork lift.
In addit}on , as shcwn in Figures 3 and 4, the box ~0 includes a plu~ali~y of spacers 47 located in the inter~or of the kox 10 along ~he bo~om wal~ 4g and the back wall 50. These spacers 47 keep the cont~iners from being placed directly against the walls 49 and 50 to allow cold vapor circul~tion ~round the containers placed the~ein. ~he sp~ce~s 47 on the bottorn wall tFI&. 4) al~o keep the containers raisec} above ~ny liquid cryogen that may h~ve coilected at the bottom of the box lo.
A temperature gauge 2 6 is mounted on the exterior wall 34 Gf the box 10, as shown in Fi~ure l.
Th~ tempera~ure gauge displ~ys the temperature inside the box 10 as detected ~y the sensor 27 loca~ed adj~cent to the in~erio~ wall 35, as shown in Figure 3~
A sensor lead 28 connects ~he sensor 27 to the gauge 26 by passing through a senso~ port 29 i~ the side wall 36 of the box 10. A commPrcially available thermometer, such as manufactured by Tel-~ru Mfg., ~odel No. VT2510-SP, i~ suit~ble for r.easuring the s~b-zero temperature in ~h~ box 10 during operation.
As shown in Figure 3, the vent por~ 30 pas~es through the s ide wall 36 adjacent to the top w~ll 37.
A conduit el~ow 31, shown in de~ail in ~iyure ~, is conne~ted to ~h~ veht port 30 outside the hox 10. The elbow 31 t S turned down~ard to direct ~he exitirg cryogen toward the floor and thus away from any nearby pe~sonnel. ~he vent port 30 allo~ws ex~ess v~por ~o e~it du~inq operation when the c~yogen is introduced into the box 10 so that t`ne box lo 7 S maintained at substantially ~tmospheric pres~u~e. Locating the vent port 30 near the top wall 37 permits the warmer vapor 2~ to rise ~nd exit ~hile the colder v2por ~emains in the ~ox 1 0 .
The insula~ed box 10 in thiC prefe~red embodiment in~ludes two cryogen sprayers 3~ ~nd 63. A
~i~st cryogen sprayer 3~ comprises two tubing coils 40, a ~yo~en supply header 3~, a cryogen inlet port 46 and a cryogen supply valve 44. The tubing coils 40, shown in Figures 3 ~nd 4, a~e each located on an opposing side wall 3~ and held in position by coil supports 42.
Each ~oil 40 has a plurality of spray ports 41 spaced at ~àrio~s intervals along ~he length of the coil 40 and p~itioned to widely ~isperse the cryogen towards g the center o~ the box 10. Prefera~ly, the spray po~ts 41 are simple holes in the tubing coils 40, but may also be ~pr~y nozzles. Each coil 40 is connected by a cryogen supply header 33 ~o 3 common cryogen inlet port 4~. The cryo~en inlet port 45 p~sses through the top wall 37 and connects ~o the supply valve 44 (~I~. 2).
This embodiment o~ the present in~ention a~so includes a second ~ryogen sprayer ~3 that comprises a tu~i~g r-n~ 64, a cryogen inlet po~t 62 and ~ cryogen supply valve 61. The tubing ring 64 is cen~rally locate~ on the top wall 37. The ~ing 64 has a plurality of spray por~s 41 spaced a~ng the length of the ring 64 and directed down towards ~he center of the box 10. ~hese spray ports 41 may also be eq~ipped with spray nozzles. The ring 64 is connected to a cryogen inlet port ~2 that passes throu~h the top wall 37 and connects to a supply valve 61 ~FIG. 2).
The cryogen sprayers 38 and 63 may ~
fashioned from a wide va~iety of m~te~ials that may 2~ withstand low temper~u~e service. Preferably, copper tu~ing is used fo~ economic re~sons, but piping and ducting may also he ~onsidered. The sprayers 38 and ~3 may be installed in a Yariety of ~onfigurations. o~
prim~ry i~por~ance is t~at the sprayer 38 adeq~tely disperse or circulate the cryogen into ~he interior of the box 10. Sprayer 63, fun~tioning much like a shower head, is installed to di~ect a flow of cryogen ~n~o an open container placed directly beneath the sprayer ~3.
The sprayers 38 and 63 shown in Figures 3 and

3~ 4 rep~esent a preferred em~o~iment. The two side tu~ing coil~ 40 are simultaneously oper~ted from a fir~ supply valve 44 and the tu~ing ring 64 is independently oper~ed from ~ se~ond supply valve 61.
This con~iguration permits a sep~r~te spray of cryogen 3S ~o be directed into the interior of an open conta~ner placed directly below the ring 64 on an as-needed _ ~ _ basis, such as when c~ rei~tively eY~ce~sive amount of residue is present in the cont~iner ~o be cleaned . The supply valves 4~ a~d 61 are for on-off service, and any one of ~he ~r~ety or commercially availa~le quarter-tuxn Ya$ves rated for cryogeni~ service is adequ~e.
The cryo~en 3torag~ tanl; 12 cont~ins liquidcryog2n. The t~n~ i2 inciudes a cryogenic expansion val~e 45 for regulating tne flow of cryogen and expanding the liqu~d cryogen into a cold vapor at the lower pressure seen a~ the outlet of the valve 45. The ~nk 12 ~ay ~e any vari~ty of commercially available cryogen~c sto~age ~anks tnat ~ypically are supplied by cryoge~ic g~ ~uppliers, such as a Dewar flask.
Likewise, the interconnecting cryogen hose 14 15 m~ be any variety o~ commercially a~aila~le f~exi~le hose for cryogenic servi~e. The hose 14 conne~ts the liquid c~o~en tank 12 to the s~pply valves 44 and ~l on the ~ nsulated box 10.
The impacting devi~e 70 m~y be any varie~y of ins~rument capa~le o~ delivering a ~uantum of ~ech~nical force to an object when striking or contacting the o~ect. One embodi~ent of such an instru~en~ is a rubber ~allet 70, as shown in Figure ~.
~t is anticipated that zn indus~rial vibrator 72, as shown in Figure 9, ~ay also be used. Preferably, it is en~isioned tha~ th~ ~ib~to~ 72 should be affixed to the cover flange 55 and a strap 73 placed over the container 60 and connected t~ ~he cover handles S7. In ~his manner, the container 60 should ~e in tight physical coupling wi~h ~he cover 51 to receive vibra~ions transmltted from the vibr~to~ 72. The inst~ument of choice depends on a subjective preference ~f ~he user o~ the present inven~ion. Factors influen~ing the ~hoic~ will beco~e apparent from the 3~ detailed description below cf the method o~ cleaning residue from a oontainer ac~o~-ding to ~he preferred embo~im~nt of the invention.
Figures 6 and 7 show one preferred embodiment of ~ ~esidue receptacle 16. The residue receptacle 1 shown is a standard 55 g~llon drum and receives the residue sepa~ated rrom ~he surf~ce of the containe~ ~o.
The ~esidue receptacle ~6 includes a cover 51 particularly suited ~o~ operation in cleaning a five g~Llon container (not shown) ~nd a one gallon container 60. The receptacle cover 51 includes a fi~e gallon ~ontainer adaptor ring 56 and a one gallon container ~d~ptor ring 54 sized ~ccordingly for a standard cylindrical co~.tainer of ~bout ~hat volume. The cover 51 may also inc~ude a serie~ of interchangeable adap~or lS rings sized to receive a oont~iner of other p~e-selected volumes. The five gallon ad~ptor ring S6, having an ineide diameter of 12 S/8 inches, is mounted Gn a b~se fl~nge 55 havinq an opening 53 ~nd ~wo h~ndle~ 57. The one gallon adaptor ring S4, havin~ an inside diamete~ of 7 3/8 inches, is mounted on a base flange 53 h~ving an opening 52. The flange 53 is sized to concentrically ~i~ within the f~ve gallon adap~or.
ring 56.
~igure ~ shows a second prefer~d embodiment o~ the ins~lated box 110. The features of this em~odiment of ~he ins~lated box llO are subs~antially the same as ~he features o~ the first embodiment of the insulated box 10 (~IGS. l through 5). For this reason, the refe~ence numbers used for the elements in Figure 8 3~ are gre~ter by an addend of 100 th~n the`refe~Pnce number~ used on the corresponding elements in F}gures 1 through 5. In this se~ond embodiment, the opening is on ~he ~op of the box 110. The door 118 is pivotably mounted on the back wall lS0 using hin~es ~25 so that tne door ll~ ts open from the front of the box l~o ~here the handle 123 is lo~ed on the door 21172~6 118. ~wo gas springs 120, mounted on opposing sides of the door l}~, miov2~ 1y conneci tne door ll~ and ~he ~ide walls 136. The ga5 springs 120 ~ssist in lifting the door 118 to an open position~ Gaskets 175 (described in detail below and sho-~n in Fig. 11) are placed around the peri~eter of the opening 122 o~ the box 110. The arrangement of the first ~ryogen sprayer (not shown) ~ener~lly conforms wi~h th~t shown in Fiqures 3 and 4.
Rowever, a second cryogen sprayer correspcndin~ to sprayer 63 in Figure 3 is not present in this embodiment.
It may be desirable to place more for~ lift poc~ets 4~ on other walls so that the a uniformly constructed box 10 ~ay be t~nspor~ed or a~a~ted for use in dif~rent positions, such as by locating two fork lift pockets 48 along the bottom wall 4~ and two along the kack wall 50.
Alterna~ively, the insula~ed box lo may b~
em~odied in a shape subctantially different than depicted in the ~igures ~r nave openings sub~t~ntially different. For example, the ~ox lo m~y h~ve a substantially cylindrical shape wi~h ~h opening on the top or on the side. Also, the ~ox lo mdy have an ~rregular snape designed to ~it the shape of an 2S irregular shaped container to be treated in it.
~ikewise, the ~ox 10 ~ay be quite large, such as a seml-trailer, capa~le of holding a plurality of large and/or sm~ll containers. Fu~ther, the box 10 ~ay be opened ~y sep~rating the two halves of ~ hox ~plit along a joint running down its middle.
3ue to the col~ opera~ing temper2tures in the ins~ated box 10, special gasketing arr~ngemen~s ~re needed ~o enable the gasXets ~o maintain resiliency and provide sealin~ cap~bility ~t the low temperatures.
3s ~or the insulated box llo shown in Figu~e ~, a gas~etin~ arrangemen~ as shown in Figure 11 is _ . - 13 -preferred. This a~angement includes two parallel silicone gaskets 175 capable of withstanding temperatures down to -26G~ (-160C~ with a durometer rating of 30 placed ~ithin grooves alonq the entire perimeter of ~he box jamb 184. The box ~amb 184 includes a metal channel 180, therm~l breaks 18~, wood f~llers 1~1 and ~2, and caulking 183. The box ~amb 184 is designed to red~ce ~he transmission of the inte~ior cold ~emperature ~o the silicone gaskets 175.
~0 A thennal break 185 is also placed on the interior CUrfaCe Q~ the door 118 For the ins~lated box 10 sh~wn in Figures 1 through S, ~ gasketing arrangement as shown in Figure lO is preferred. This arrangement includes one silicone gaske~ 75 capable of withstan~ing temperature~
down to -260~F (-160C) with a duromete~ rating of 30 placed within a ~roove ~long the entire perimeter of the box jam~ 84. The box jamb ~4 includes a metal channel 80, thermal ~eaks &6, wood fillers 81 2nd 82, 2~ and caulkinq 83. The box jamb 84 is de~igned to reduce the trancmission of the interior cold ~emperature to the silicone gasket 7~. The box jamb 84 also includes two calibrated resistance wire~ 79, preferably g g~uge, placed within two pa~llel grooveC 78 in th~ wood filler 81 around the entire peri~eter of the box jamb 84. ~he wires 79 ~re connected in a para~lel cirCuit, with a setting at 3~ v~lts, 6.40 a~ps resulting ~n a wire temperature of approximately ~gO~ (8g~) ~ased on 2~ lineal feet of 9 gau~e calibrated resistan~e wi~e when used in an insulated box 10 sized to recei~e one 55 ~llon container. A lO gauge aluminum plate 77 is placed direc~ly o~er ~he wires 79 around the entire perimeter of the box jamb ~4 to conduct heat to a silicone gas~et 76 mounted on the door 18. The silicone gasket 76 is rated ~or ~se wlth the he~ted calibra~ed wires 79. A ther~al ~reak 85 ~s placed on the interior surface of the door 118.
Alternatively, when the embodiment of the ins~l~ted ~ox 10 shown in ~igure~ 1 th~o~gh 5 ~s ~ntended for only ~ntermitten~ operation, than the g~ket arrangement embodied in Figure 11 may be ~uitable. su~h inter~i~tent oper~tion woul~ be limi~ed to pe-riods of about one hour contihuous ope~at~on with the lowest operating temperature about -240~F (-~SO~C).
A pre~e~red embodiment of the method of the present invention may be most expeditiously de~cri~ed by ~e~e~ence to the afore-~entioned preferred embodimen~ of ~he appara~us. A container 60 ~ay ~e cleaned cryogenically by placing the container 60 having residue adhered to its surface into an insulated ~ox 10, placing a cold vaporized c~yogen illtO the insulated box 10 such tha~ it cont~ts and cools ~he cont~ne~ 60 ~nd resi~ue, removing the ~ontaine~ G0 ~rom the insul~ted box 10 ~fter the residue has coole~
to a temper~ture that renders it substan~i~lly embri~ed, i~pac~ing the container 60, the energy of which fragments the res~due and separates it from the surface of the con~ainer 60, and then removing the separ~ted residue ~eaving a substantially resid~e-free 2S cleaned con~ainer.
The present invention may ~e applied to clean a wide variety of residues from containers. Th~se residues in~lude, ~ut are not limi~ed to tars, lu~ricant~, ~astics, inks, coatings, solvehts, ~dhes~es/ glue~, ~e~lant~, v~rni~he~, paints, pain~
pigmen~s, enamels, resins, pl~stici~ed m~ter~al~, grease~, cementatious materials, etc. The present inven~ion may be ~pplied to cont~iners h~ing ~
com~ination o~ di~erent residues adhered to its 3S surface. The residues may be fresh, that is, in thei~
commonly useful for~, liquid, viscous, or ~acky. Also, 211720~
_ - 15 -the residues ~y have a dried sur~ace film. Moreover, the present invention may be ~pplied to residues ~hat have become dried, solidif~ed o~ b~ked-on. Gener~l~y, the present invention wor~s ~uickly wi~h residues that thinly coat the surface of the container, but also may be effec~ive where the residue is several ~nches thick, or gre~ter. ~ypically, the p~esen~ invention i~
directed towards Gleaning the ins~de sur~aces of containers, but, as will become apparent fro~ the followin~ de~ailed description, oan also clean ~he outside surfaces.
~ he present invention may ~e applied ~o con~ainers made rrom ~etal, plastlc, polymers, resins or a compo~ite of different ~aterials. The present lS invention may substan-ially remove the residue from the container so that the container ~ay be re-used or meet government re~uirements for non-h~zardous waste disposal. The containers pr~fer~bly range in size betweeh abbut ~5 gallons ~nd about one gallon. The 2Q method of the preferred embodimant is particularly w~ll suited for commonly used containers of fifty-five, five and one gallon volume. Mos~ preferably, the containers have a subst~ntially cylindrical shape with a full opening at one end. The residue ~ay be removed easiest ~5 from ~uch a containex, but the present inve~ion may be effective on other containers, such as those having tight corners and a sm~ll opening.
According to the preferred em~odiment, the resi~ue laden container 60 is placed in an insulated b~x 10. More than one container 60 may be placed in the box 10 if space permits. The ins~lated box 10 contains the cold ~apor in a small space so it may be e~ficiently utilized to cool ~he containers 60 and residue. The containers may be placed alone, or wi~h a m~ltitude of other containers, into the insulated ~ox - lS -211720~

10. The box 1~ is then sealed ~losed an~ ~ryogenically cooled.
Cryogens are gene~ally gases that have a very low boiling point. Nitxogen (N2), f~r example, has a bo~in~ point of -320F ~-195C~ at a~mospheric pressure. The cryo~ens m~y ~e re~dily stored as a liquid in s~e~ially designe~ stor~ge t~nks 12. A ~ange of li~uid cryogens, or cryogenic ~gents, or cryogenic gases are ~ommercialty avai~ble that theoretically could be used with the present invention. These include, but are no~ limited to, Nitrogen, ~elium, Argon, and Car~on 3ioxide. ~owever, some cryogenic gases are flammab~e or require extreme precautions and equipment to sarely use, and are therefore not preferred. Ni~ro~en is a pre~erred cryogen because o~
its ~e~ative s~fety in use ~n~ e~on~mi~l low cost.
Nitrogen is an inert g~s that is not flam~able, is non-~oxic and does not raise a risk of reaction with ~esi~ue or equipment ~aterials. ~itrogen is t~e largest c~n~ituent of air so i~ ~n safety di~sipa~e into the environ~nen~. Special ~fety equipment is not required when u~ing ~itroge~ cryogen with the present invention, other than minor prote~ti~e gear for the cold tempe~atuxes. Howe~er, a laxge, well ventilated roo~ is preferxed for using the present invention to avoid oxygen depxi~ation due to the vaporized ~it~ogen cryogen displ~cing th~ 2i~ from the room.
Preferably, a cold ~apori~ed cryogen is pl~ced in the insul~ted box 10 to contact and cool the con~ainers ~0 and residue. Most preferably, the ~ox 10 is pre-coole~ prior to p~a~in~ the containers 60 therein by introducing the vapori~ed c~yogen into the empty ~ox 10 for a ~hort period of ~ime, ~uch as 10 to ~0 minutes, to redu~e its temperature. Typically, the.
internal en~ironment of the box 10 may ~e pre-cooled down to a temperature of a~out -150F (-lOO~C~ or less -as measu~ed on the teDper~tu~e ~auge 26. The colder the pr2-~ool, the less time required to cool the containers ~0 ~nd residue.
As an alternâtive, it m~y be more e~onomical 5 ~o use standard refrigera~ion equipment ~o pre-~ool a large insu~ated hox i~ste~d o~ using ~ryogens. For example, when the insula~ed box is the size o~ a semi-trai~er, i~ is econ4mi~al ~o operate refrigerat~on equipment to maintain a pre-cool~d box and only use the iO cryo~en a~ter containers are placed inside ~he box.
After the containers ~0 are in the insulated box 10, the door 13 is sealed closed and the l~tches 24 axe se', ~hen the crycgen, preferably Nit~ogen, is in~rod~ced ~y opening ~ supply valve 44 and expansion ~alve ~S on the liquid cryogen storage tank 12. Liquid Nitrogen is under about 22 psig pre~sure in ~ewar flask 12 and expands in~o a v-apor ~s i~ drop~ ~o s~bst~ntial~y a~mosphe~ic pressure across the ~alve 45.
Th~, the ~old ~apo~i~ed ~ryogen flows through the cO cryogenic hose 14, ~hrou~h ~he open valve 4~, ~hrough the tubing ~ils 40, exits through the spr~y por~s 41, enter~ the interior of the 'DOX 10 and co~,t~cts t~e residue and containers ~0. Preferably, for most applica~ion~, ~he cryo~en is cofflple~ely vaporized ~efore exiting the spray ports 41. ~his ~axi~izes the efficlent ucage of cryogen, ~s well a~ ~educin~ hazards fxo~l personnel ~eing exposed to li~uid cryogen. Thus, any liquid cry~gen accumulating ~ the bottom of the box lO gener~lly is waste~ul and not desired.
3G Therefore, if ~he operating ~emper~ture of the box lo is allowed ~o ge~ too low, su~h as less than a~out -2600~ (-160~C~ when using Nitrogen, then the cryogen may no~ co~ple~ely vapori2e before exiting the coils 40.
~oweYer, cer~ain s~tua~ion~ ~ay req~ire ~h~t liquid cryogen be introd~ced into the ~ox 10. When a 211720~

container has very thick resi~e ihside it, it may be desired to spray liquid cryoge~ from the spr~yer 63 directly into ~he interior Qf the conta~her and on~o the thick l~yer of residue to effect rapid and S ~oncentrated cooling ther Sprayer ~3 is designed with a short flow path to ~-ni~ize the amount o~
v~porizat7oh occurring therein, so that some liquid cryogen may exit from the ring ~4 e~en though the box operat7 hg tempera~Ure is not 50 cold as to allow liquid 1~ C~yogen to exit from the coils 40.
Less prefera~ly, though, ~he system ~ould be des~gned to spray atomize~ liquid cryo~en on the containe~s and residue ~rom ~11 the sprayers. But, this ~.ay res~lt in accumul~tions of liqu;d cryogen in the bo~tom of the ~ox 10.
The residue rapidly ~hanges propertt es as it rapidly cools. It is theorized that the res~due ther~lly contra~ts as it cools a~ a different r~te th~n the containPr and that this di~feren~ial contraetion lessens the adhesive b~nds ~etween the residue a~d t~e surf2ce o the containe~ 60. Water~
based residue typically expands when it solidifies, kut the differential mo~ement of the residue and surface of the container 50 would still be present. ~n addition, ~5 ir n~t already solid, the residue sol~difies and ~ecomes substantially embrittled as it ~o~ls to sub-zero temperatures. It is believed that even if the residue and container materials have similar rates of the~mal cont~action, the embrittlemeht ~f the res~due lessens the adhe~ive bon~s between the residue and the cont~iner.
The residue laden containers ~0 ~ho~ld remain in contact with the cold cryogen until at least nearly all of the residue becomes substan~ially embrittled.
The time required to embrittle the residue depends on several facto~s such as the thickness of the ~esidue - la --and the ope~a~ing temperature in the box 10. Also, other factors inclu~e, but are not limited ~o, the type of resi~ue fflateri~l being cleaned, the type of ~ontainer ~.aterial (as certain ma~er~ conduct he~t S faster than others), the quantity of containers Gooled at the same ti~e, the quantity o~ resid~e, the pre-cool temperature of the box as well ~s the type of c~yogen used.
The ~ooling time ~nd opera~ing te~perature are in~erdependent. The residue is not required to cool to the sele~ted operating temperature. Rather, the lower temperatures will result i~ faster heat trans~er rates and reduce the a~ount of time requi~ed ~o e~brittle the residu~. Thus, economic trade-offs are involved in the selection of the opèratin~
température. Lower temperatures and shorter cooling times will require ' he use of more cryo~en. On the other hand, higher temp~ratures and longer ~ooling times will ~orrespondingly increase labor costs.
Subject to the fore~oing, for mos~
applicatiohs, lower te~peratures and faste~ cooling times are preferred. This can ~e acco~plished ~y int~oducing sufficieht cold vapori~e~ cryogen into the insulated box 10 with ~ontainerg ~0 inside to ~aintain ~5 a temperature of be~ween about -100F (-75C) and about -300F (-185C). Pre~er~b~y, ~he temperature will be maintained between about -150F (-10~C) and about -250F (-~55~).
During th~ cooling step, as the temperature in the ~ox rises above its desi~e~ value, more cryogen should b~ introduced to lower the te~per~ture back to the desired value. This may be accomplished ~y manua~ly ad}usting the valve 45 or by using an automatic temperature con~roller ~egulating a cryogenic control ~alve. Maintaining ~he internal environment o~
the insulated box wi~hin the ~ost preferred te~perature -- lg _ - 20 -range for a period of a~out 4 to ~bout 6 ~inutes ~
su~ficiently embri~tle thin coatings of most residues.
Of course, this time may vary depending on several factors. Tnick layers of ~esidue will require more cooling time. Fo~ example, a s~x ~ nch l~yer of coating material ~ay reguire up to abou~ 15 to 20 minutes of treatment ti~e.
Afte~ ~uffi~iently coo~ing ~he re~i~ue la~en containers 60, the box 10 is opened and the containers are rem~ed for impactin~ one at a time. The door 18 is closed after the remo~al of each container to keep the containers remaining in the ~ox 10 cool. The removed container is impacted kefore any substantial wa~ihg can occur~ The impact causes the em~rittled residue to fragment into small pieces and separa~e from the surface of the ~ontainer 60. The expected emDrit~lement is of a degree such that several ~nual blows to the outside of the c~nt~iner 60 with a rubber mallet will su~fice to fr~gment and separat~
s~bstantially all of the residue. If the residue does not separate after a few strikes, then the containe~ 60 ma~ ~e placed back into the cold box 1~ to cool the residue, further embrit~llng it and w~ening the adhesive for~es bonding the r_sidue to the cont~iner surface.
I~ is appa~ent that if the con~ainers are to be re-used afte~ cleaning, ~hen ~he con~ainers should no~ be left in the cold box 10 for to~ long ~ period~
Although the residues typically become embrit~led at a hi~her temper~ture than does the container 60, p~astic will become embrittled ~t a higher temperat~re th~n metal. If the con~aine~ gets too cold and becomes substantially em~rittled, as may happen with a short~r cooling ~ime for plastic containers than for metal containers, then the impacts to remove the residue may also fracture embrittled portion~ of the container.

21172~

This would render the container unfit for re-use after cleaning.
Presuming that the cont~iner 60 an~ residue h~ve been properly coo;e~, ~here are a variety of ~ethods th~t may ~e used tc impa~t the container 60.
hard object, sush as a rubber mallet ?0, ~ay be manually struck ~gainst the exterior of ~he container 60. Conversely, the container 60 may also be s~ruck against ~ hard objec~. Also, L~ ~ S ~nticipated ~at an industrial type vibrator 72 m~y be used. The vibra~or 72 ~o~ld impart a series of consecutive small i~pacts to the container. ~ikewise, the ~ibrator 72 may induce internal vi~rations in the residue ~nd cont~iner 60 causing the resLdue p~rtiGles to impact each other and the container. In brief, it is belie~ed that impacting applies mech~nical ener~y to the oon~ainer 60 greater than th~ e~brit~led r~id~e can ~bsorb, resulting in the physical failure of the solidified resi~ue and the bonds to the container surf~oe. The physical f~ilure ~0 results in frag~entation and separation of the re~i~ue from the container surface.
Preferably, tne residue is remo~ed by impacting the container in conju~ction with placing it in an invcrt~d position over a residue receptacle 16.
As the impa~t lo~sens and breaks apart the ~esidue, the residue fragments fall ~y gravity into the re~ep~acle 16. For example, as shown in Figure 6, a one gallon container 60 is removed from the insul~ted ~ox and placed upside down within the ~aptor rin~ 54 of the receptacle ~over 51 which is positioned over th~
residue recep~acle 15 opening. The containe~ ~0 is then struck on the sides and the bottQm with a rubber mallet 70. Substantially alt of the residue fragments and sep~r~te~ from the surface of the container 60.
35 The residue particles in the interior of the conta-ner then fall th~ough the receptacle cover ~pening 52 into _ - ~2 -to the receptacle ~6. Any res~dues ~hat separ~ted from the exterior of the cont~iner f~ll OhtO the recep~acle cover 51 and is manually placed ~n~o the receptacle 16.
Al~ernatively, particularly with large con~iners, such as an 85 gallon ~rum, the residue re~ept~le may be a large plastic sheet, or a large shallow p2n. The re~idue would be removed, in tnis c~se, by turning over the drum wi~h the open end on the sheet. The container would b~ imp~cted with a rubber mallet ~o fragment ~he residue and separate i~ from the container surface. The residue particles would fall onto the sheet. The sheet could ia~er be gathered to tran~fer th~ re~i ~ue p~t~cles i~to a morP appropria~e storage vessel.
~s an example of cleaning residue from containers, five-gallon metal containers were cle~ned under the following ~onditions. The insulated box lO
was pre-cooled to -150F (-100C) ucing the cold cryogenic vapor from a cryogeni~ storage tank filled 2~ with liquid Nitrogen. Twelve residue laden five-gallon metal containers were placed in the insulated box lO.
The residue consisted of a water-based baking enamel chem-aq~a series sold by She~win Willia~. The residue was pax~ially solidified in some case~, having an 2~ average thickness of less than one~eighth inch, ~dhered ~o the inte~ior surface of the containers. The Nitrogen w~s introdu~ed into the box intermi~tently to maintain a temperature of -150~F (-lOO~C) for a period of 5 -~inutes. After ~his cooling per~od, ~he containers we~e removed f~om the box lo one at ~ time and pl~ced on a receptacle cover 51 set up for a five gallon size container. E~ch con~iner 60 was impacted several ti~es to the sides and ~he up-turned bottom with a ru~er mallet 70 for l~ss than 30 seco~ds.
Subs~antially all o the residue was remo~ed f~o~ ~he 211~206 con~ainer so 'ch~t the conta7r~2rs were cle~ned for ~e-use .
A similar method may be follow~d to cryo~eni~ally reduce the bulk volume of ~ plastic $ container 60. The diff~rence a~c:ording ~o this me~hod, is that the container 60 re~ains in the insulated box lo ~til the container 60 cools ~o a temperature su~h that su`~stantial portions of the con~ainer ~0 become em~rittled. After re~.o~ting 'che plastic conta- ne~ ~0 from ~he insulated box 10, sufficient stress shoul~ be applied to ~he container 60 to ~racture the embrittled portions, thereby causing the container 60 to break apa~t. ~he bu~k volume of the ~ro~en po~t~ Oh5 ~f the container is substantially less than the contalner's original bulk volume.
Typically, t~he ~emperat~re at which a pla~tic container becomes em~brittled i~ signi~icantly less t~an the temperature at which resl'due beco~es embri~tled.
Thus, to cool the container to a ~owe~ temperature, lt may ~e necessary to keep the container in the insulated ~ox 10 for a long_r period of time if operatin~ at the same temperature as for cleaning residue. Numerous factors ~ffect the ~mount of time required for the appropriate cooling. These factors include the num~er of cont~iners being cooled at one time, the type of cont~ine~ material, the thickness of the container, the size of the con~ainer, ~he pre-cooled ~emperature in the box befo~e placing the oon~aine~ therein, and the oper~ ~ing temperature main~ained during cooling.
Subject to the above fa~tors and the prev~o~sly described economic trade-o~fs in the operationa~ time-temperature interdependency, for ~o~t size reduction applications, preferably the temperature in the ~ox 10 is maintained ~etween abo~ -200~F
~-130C) and about -250~F (-155~

~11 72û6 _ - 24 -~fter oooling, ~he plastic container is removed from the ~o~ an~ stre~sed to the point of fracture. The stres~ ~y be applied in different ways.
The contair.er may be i~pa~ted by a heavy object. The ~Ohta~ner may strl~e a hard object. Compressive forces may ~e applied ~o ~he container. ~umerous commercially ava~l~ble equipment for compacting waste applies the ~ype o comp~essive force required to fracture and break apart the em~rittle~ container. ~or ex~mple, i0 Drum C~usher In-Plant Model No. 700Q manufac~ured by Drumbeaters of America Inc., is an exa~ple of a suit~le con~ine~ compactor. A plastic container that woul~ otherwi se reboun~ to i~s o~ig5nal shape ~fter compac~inq is broken apar~ ~y ~his embodi~ent of the present invent-on so that it maintains the compressed bulk volume.
As an example, a fif~y-five gallon container ~de from polyethylehe, ~DPE No. 2, was placed in an pre-cooled insulated box 10. Vaporized Nitrogen w~s then introduced in~o ~he box ~ intermittently to maintain i~ at -200~F (-130C). After about ~en minutes, the container was removed a~d placed in a compactor that fractured the container, breaking it apart and crushing it.
One aspect of the invention is also directed to a method for cryogenically cleaning residue ~rom containers and reducing the ~ulk volume of ~he containers. This method combines the previously ~e~c~i~ed ~ethod for cleanin~ residue from containers and the method ~or reducing the bul~ volu~e of the cont~iners. Thi~ method m~y ~e practiced by first cryogenically cooling the containers to a first temperature sufficient to ~lean the residue therefrom, cleaning o~t the residue, ~nd then cryogenic~lly cooling the containers a second ~ime to a lower second temper~ture sufficient to embrittle the container or breaking it apart to reduce its }~ulk volume.
Alternatively, this method may be pra~iced by perrorming only a single cooling step and a single 5 impacting ~tep. ~ere the mechod for cryogenically trea~ing a container ~or reducing its bu~k volume is operated on residue iaden containers Upon applying force to break apart the ~ontainer, the residue fra~nents an~ separates from the ~ontainer as the lQ container f~actures and breaks apart. ~onventional separation methods then may be applied if desired to segregate the residue ~ragments ~rom the container pieces .
~he present invention may also ~ind broader application, such as in reducing the bulk volume of metal containers. I~ is anticipated that the present invention ~ay be effective to reduce the bulk volume o~
me~al containers using su~stantially less ~orce to compact the contalner than otherwise required. For inst2nce, af~er a metal container is cooled to become substan~ially embr~ttled, ~tre~s ~pplied to ~ ~ill cause i~ to ~ra~tu~e an~ break apart. ~t is expected that the metal container may be co~pacted by ~
compacting device that did not h~ve sufficient compressive force to compac~ the metal container when it w~ at ~mbient temperature. ~ikewise, ~n imp~ct from a sledge hammer, that may only dent a metal con~ainer a~ ambient temperature, is expected to fra~ture the same container into numerous small pieces when the container i~ cooled to a low temperature ~here the metal becomes embrittle~.
As a foreseea~le applicatton, a standard propane bo~tle may be cryogenically treated by placing it the insulated boY~ 10 ma~int~ined at -250~ (-155C) 35 by intermitten~ sprays of vapor from a Nitrogen crycgenic tank 12 for a period of about 10 minutes.

~ - 26 -When the propane bottle is sufficiently embrittled, it would be removed f~om the insulhted box 10 and placed in a comp~tor, for e~mple, Drum Crusher Portable Model No. 8000, manufactured by ~rumbeaters of America Inc. Typica~ly, it is presumed that a commercially available steel propane bottle at ambient temper~tures ~ay have sufficient strength to withst~nd more than lOO,ooO pounds of compressive force. This parti~ular compactor is capa~le of de~ivering ~00,00~ pounds o~
lo compressi~e force which is expected to be sufficient to crush the embrittled propane bottle.
The advantages of the preferred embodiments are numereus. The preferred em~odi~ents avoid the use of solvents and ~the~ wash liquid~ as~ociated with lS tra~itional ~le2nin~ meth~ds so that the amount of hazardous m~teri~l for disposal i~ limited ~o the ori~in~l residue itself. ~oreover, the res~d~e may be recycled or re-used ~ince it is not contaminated by wa~h li~uids or solvents.
2~ The described methods require less equipment and less labor to oper~e than tra~itional methods of cleaning and reduces h~alth risks to the employee. The descri~ed methods are more economical than tradi~ional cleaning methods. The pre~erred embodi~ents 2~ su~stantially remove the residues from the container to meet governmen~ disposal ~e~uirements and industry req~irements for re-use or re2ycle of the container.
In addition, aspects of the invent~on allow plas~ic containers to be reduced in bulX volume ~si~g traditioral e~u~pment and methods for metal ~ontainex~.
Plastic containers may be e~fectively reduced in bulk volume without ~he need for ~ngerous and expensi~e ~hredding equipment.
~he pre~erred apparatus of ~he presen~
invention lnclùdes ~ sealed insula~ed box ~o safely contain the low tempexatures d~xing the ccoling - 2~ -211720~

_ - 27 -opera~ion. ~o~-eo~er, ~ecaus~ the pre~erred embod~ment o~ the invention applie, vapori2~d cryogens for ~ooling, th~ hazards and ineffici~ncies of using exp~sed liq~id cryo~en~ ar2 avoided.
It should be appr~ciated ~h~t the methods and apparatus of the presen.t invention ~re cap~ble of bein~
inco~por~ted in the form o~ ~ variety of e-ln'~odi~ent~, on~y ~ few of which have been illustra'ed and described above. The in~ention may be embodied in other forms without departing from it~ spi~it or essential characteristics. For e~ample, impacting o~ the containers could '~e carried out while the ~on~ainers are still in the insulated box, Als~, rather than a hinged door as shown, o~her arrange~ents for opening and c~osin~ the box ~0 may be used. The descri~ed embodiments are to be ~onsidered in a~l respects only ~s illustrative ~nd not restrictive, ~nd ~he scope o~
the invention is, therefcre, indicated by the appended claims r~ther than by the foregoing descriptlcn. All changes which come ~ithin the meanlng and range or eq~ivalency of the e~aims are to be embraced within their scope.

Claims (39)

WE CLAIM:

1. A method for removing residue from the surface of containers comprising the steps of:
(a) cooling the container and the residue to effect substantial embrittlement of the residue adhered to the surface of the container; and (b) cooling the container to fragment the residue and cause it to separate from the surface of the container.

2. A method according to claim 1 wherein the cooling step is carried out by placing the container in an insulated box.

3. A method according to claim 1 wherein the cooling step is effected by contacting the container and residue with a cryogen.

4. A method according to claim 3 wherein the cryogen is vaporized prior to contacting the container.

5. A method according to claim 3 wherein the cryogen has a boiling point of less than -100°F (-75°C) at atmospheric pressure.

6. A method according to claim 3 wherein the cryogen is Nitrogen.

7. A method for removing residue from the surface of containers comprising:
(a) placing at least one residue laden container and vaporized cryogen inside a box;
(b) contacting the container and residue with cold cryogen for a period of time sufficient to effect substantial embrittlement of the residue adhered to the surface of the container;
(c) removing the cooled container from the box;
(d) impacting the container with sufficient force to fragment a substantial portion of the residue.
and effect its separation from the surface of the container; and (e) removing the residue fragments from the container.

8. A method according to claim 7 wherein the cryogen is placed in the box after placing the container in the box.

9. A method according to claim 7 wherein the cryogen is placed in the box both before and after placing the container in the box.

10. A method according to claim 7 wherein a sufficient supply of cryogen is placed in the box at substantially atmospheric pressure to reduce the temperature inside the box to about less than -150°F
(-100°C).

11. A method according to claim 7 wherein the method further comprises after step (c) placing the cooled residue laden container in an inverted position over an open residue receptacle, impacting the container by a series of mechanical strikes to the external surfaces of the container, and removing the residue fragments gravitationally into the residue receptacle.

12. A method according to claim 11 wherein the impacting is effected by a vibrator.

13. A method according to claim 7 wherein the container has a volume of between about 35 gallons and about 1 gallon.

14. A method according to claim 7 wherein the container has a volume of between about 5 gallons and about 1 gallon and a substantially cylindrical shape.

15. A method for reducing the bulk volume of containers to be disposed of comprising:
(a) cooling the container to effect substantial embrittlement of at least a major portion of the container; and (b) stressing the container to fracture and break apart the embrittled portions of the container thereby reducing the bulk volume of the container.

16. A method according to claim 15 in which the stressing is effected by impacting the container.

17. A method according to claim 15 in which the stressing is effected by applying compressive forces to the container.

13. A method for reducing the bulk volume of containers to be disposed of comprising:
(a) placing at least one container and vaporized cryogen inside an insulated box;
(b) contacting the container with cryogen for a period of time sufficient to effect substantial embrittlement of at least major portions of the container;
(c) removing the cooled container from the box; and (d) applying stress to the container to fracture the embrittled portions of the container thereby reducing the bulk volume.

19. A method according to claim 18 wherein the container is cooled to a temperature between about -100°F (-75°C) and about -300°F (-185°C).

20. A method according to claim 18 in which the cryogen is placed in the box at substantially atmospheric pressure to reduce the temperature inside the box to about less than -150°F (-100°C) prior to placing the container therein.

21. A method according to claim 18 in which the containers have a volume of between about 85 gallons and about 1 gallon.

22. A method for removing residue from a container and reducing the bulk volume of the container comprising the steps of:
(a) cooling a residue laden container for a period of time to effect substantial embrittlement of the residue adhered to the surface of the container and substantial embrittlement of at least a major portion of the container;
(b) impacting the container with sufficient force to fragment a substantial portion of the residue and effect its separation from the surface of the container; and (c) applying stress to the container to fracture and break apart the embrittled portions of the container thereby reducing the bulk volume of the container.

23. A method according to claim 22 in which the cooling is effected by contacting the container with cryogen in an insulated box.

24. A method according to claim 22 in which the impacting is effected by a vibrator.

25. A method according to claim 22 in which the stress is applied by a compactor.

26. An apparatus for cryogenically treating containers comprising an insulated box having an opening sufficiently large to allow placement and removal of at least one container, a vent port, a door mounted on the box to seal closed the opening and at least one cryogen sprayer having a plurality of spray ports.

27. The apparatus for cryogenically treating containers of claim 26 wherein said at least one sprayer comprises at least two coils, each coil being mounted on opposite interior side surfaces of the insulated box.

28. The apparatus for cryogenically treating containers of claim 27 further comprising a sprayer mounted on the top interior surface of the box having a plurality of spray ports.

29. The apparatus for cryogenically treating containers of claim 26 further comprising a temperature sensor to measure the temperature of the vapor inside the box.

30. The apparatus for cryogenically treating containers of claim 29 further comprising a temperature gauge for displaying the temperature sensed by the temperature sensor, the temperature gauge being mounted to the exterior of the insulated box.

31. The apparatus for cryogenically treating containers of claim 29 further comprising a control valve connected to the sprayer and a temperature controller receiving a temperature signal from the temperature sensor.

32. The apparatus for cryogeniocally treating containers of claim 26 wherein the opening is located on the top of the insulated box.

33. The apparatus for cryogenically treating containers of claim 26 wherein the opening is located on a side of the insulated box.

34. The apparatus for cryogenically treating containers of claim 26 wherein the insulated box is sufficiently large to receive at least one substantially cylindrical container having a volume of about 85 gallons.

35. A system for cleaning a residue laden container comprising:
(a) a tank for the storage of liquid cryogen;
(b) an insulated box having a cryogen sprayer;
(c) a hose interconnecting the tank and the sprayer in the insulated box;
(d) an impacting device located adjacent to the insulated box for impacting the cooled containers removed from the insulated box to effect fragmentation and separation of the residue adhered to the surface of the container; and (e) a residue receptacle for receiving the separated residue located adjacent to the impacting device.

36. The system of claim 35 further comprising a residue receptacle cover located on the residue receptacle, the receptacle cover having an opening to receive the separated residue falling from an open top of an inverted container placed thereon.

37. The system of claim 36 wherein the receptacle cover is selectively adjustable to receive a cylindrical container having a volume of between about 5 gallons and about 1 gallon.

38. The system of claim 37 wherein the receptacle cover includes at least two concentrically fitting adaptor rings, at least one ring sized to accept a 5 gallon container, and at least one ring sized to accept a 1 gallon container.

39. The system of claim 38 in which the impacting device is a vibrator operable with the residue receptacle cover.