CA2119994A1 - Rotary tunnel freezer - Google Patents
Rotary tunnel freezerInfo
- Publication number
- CA2119994A1 CA2119994A1 CA002119994A CA2119994A CA2119994A1 CA 2119994 A1 CA2119994 A1 CA 2119994A1 CA 002119994 A CA002119994 A CA 002119994A CA 2119994 A CA2119994 A CA 2119994A CA 2119994 A1 CA2119994 A1 CA 2119994A1
- Authority
- CA
- Canada
- Prior art keywords
- drum
- nozzles
- atmosphere
- rotary tunnel
- stirring
- Prior art date
- Legal status (The legal status 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 status listed.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
- F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air
- F25D3/11—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air with conveyors carrying articles to be cooled through the cooling space
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Freezing, Cooling And Drying Of Foods (AREA)
Abstract
ABSTRACT
ROTARY TUNNEL FREEZER
A rotary tunnel freezer comprises a drum which is rotatable about its longitudinal axis. In use, liquid nitrogen is introduced into the drum through a spray header. Heat transfer throughout the drum is enhanced by further nozzles positioned at 500mm centres along the drum. The nozzles are positioned to eject gaseous or liquid nitrogen substantially tangentially to the drum a few centimetres from its inner surface. The nitrogen leaving the nozzles vigorously stirs the atmosphere in the drum and significantly enhances heat transfer there-by increasing the maximum production rate of existing rotary tunnel freezers or allowing shorter, and less costly, rotary tunnel freezers to be used for a given duty.
ROTARY TUNNEL FREEZER
A rotary tunnel freezer comprises a drum which is rotatable about its longitudinal axis. In use, liquid nitrogen is introduced into the drum through a spray header. Heat transfer throughout the drum is enhanced by further nozzles positioned at 500mm centres along the drum. The nozzles are positioned to eject gaseous or liquid nitrogen substantially tangentially to the drum a few centimetres from its inner surface. The nitrogen leaving the nozzles vigorously stirs the atmosphere in the drum and significantly enhances heat transfer there-by increasing the maximum production rate of existing rotary tunnel freezers or allowing shorter, and less costly, rotary tunnel freezers to be used for a given duty.
Description
ROTARY TUNNEL FREEZER
FIELD OF THE INVENTION
This invention relates to rotary tunnel freezers.
BACKGROUND OF THE INVENTION
Typically, rotary tunnel freezers comprise a drum ; which is inclined at an angle of a few degrees to the horizontal and which, in use, is rotated about its longitudinal axis.
Product to be frozen is introduced into the upper end of the drum and, as it passes through the drum, is cooled by direct heat exchange with cryogenic fluid, for example liquid and/or cold gaseous nitrogen. The flow of cryogenic fluid and product through the drum may be co-' current or counter-current.
Typically, the liquid nitrogen is introduced via a spray header located at one or other end of the drum as shown in, for Example US-A-l 601 298; US-A-l 492 488 and ~` UK-A-l 474 471.
Although there is excellent heat transfer between the cold nitrogen and the product to be frozen in the area where the liquid nitrogen is introduced into the drum the rate of heat transfer diminishes quite rapidly ~-- away from this area.
In UK-A-1 474 471 product is cooled in a rotatable drum in counter-current flcw to a stream of nitrogen which is introduced through a spray headed ad;acent the product outlet. Part of the cold nitrogen vapour leaving the drum at the product inlet is compressed and blasted axially into the drum via a nozzle mounted adjacent the product outlet. This arrangement has several disadvant-`:
ages. In particular, the effect of the blast decreasesextremely rapidly as the distance from the nozzle in-creases. In addition, the recirculation fan absorbs energy and, at the same time, imparts heat energy to the recirculating gas~
~i, ~ ' .. _ ~ 21199~
, .~ , It will be appreciated that it is impractical to install fans in the rotatable drum because of the rota-tion of the drum, the risk of damage from and to the product and the low temperatures present.
SUMMARY OF THE INVENTION
~" According to the present invention there is provi-ded a rotary tunnel freezer comprising a drum which, in ~` use, is rotatable about its longitudinal axis, and means for introducing a cryogen into an end of said drum, wherein said drum is provided with a plurality of noz-zles arranged at intervals along a major portion of the length (F) of said drum for introducing cryogenic fluid into said drum and stirring the atmosphere therein.
Advantagèously, said means for introducing cryogen into said end of said drum comprises a spray header and said plurality of nozzles are disposed on an extension thereof.
Advantageously, said nozzles for stirring the atmo-sphere are disposed to introduce cryogen into said drum substantially tangentially thereof and, preferably, closely adjacent the radially inner surface of the drum.
Conveniently, the nozzles for stirring the atmo-sphere are disposed on generally outwardly extending ~i, extensions emanating from a common supply bar.
Typically, said nozzles for stirring the atmosphere are disposed at centres of from 250mm to 750mm, prefer-ably from 400mm to 600mm, and advantageously at 500mm centres.
Preferably, said nozzles for stirring the atmo-sphere are disposed over at least 70% of the overall length of the tunnel, more preferably over at least 85~, and advantageously over that part of the drum which is -~ not occupied by the spray header.
Typically, the spray header will comprise a plural-~,~ ity of nozzles separated at 25mm - 50mm centres. The ,~ ~
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output of the nozzles in the spray header and the noz-- zles for stirring the atmosphere may be the same for a given pressure or may differ. Typically, The nozzles in - the spray header will have an outlet diameter of from 1.5mm to 3.Omm whilst the nozzles for stirring the atmosphere may have an outlet diameter less than or equal to lmm.
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FIELD OF THE INVENTION
This invention relates to rotary tunnel freezers.
BACKGROUND OF THE INVENTION
Typically, rotary tunnel freezers comprise a drum ; which is inclined at an angle of a few degrees to the horizontal and which, in use, is rotated about its longitudinal axis.
Product to be frozen is introduced into the upper end of the drum and, as it passes through the drum, is cooled by direct heat exchange with cryogenic fluid, for example liquid and/or cold gaseous nitrogen. The flow of cryogenic fluid and product through the drum may be co-' current or counter-current.
Typically, the liquid nitrogen is introduced via a spray header located at one or other end of the drum as shown in, for Example US-A-l 601 298; US-A-l 492 488 and ~` UK-A-l 474 471.
Although there is excellent heat transfer between the cold nitrogen and the product to be frozen in the area where the liquid nitrogen is introduced into the drum the rate of heat transfer diminishes quite rapidly ~-- away from this area.
In UK-A-1 474 471 product is cooled in a rotatable drum in counter-current flcw to a stream of nitrogen which is introduced through a spray headed ad;acent the product outlet. Part of the cold nitrogen vapour leaving the drum at the product inlet is compressed and blasted axially into the drum via a nozzle mounted adjacent the product outlet. This arrangement has several disadvant-`:
ages. In particular, the effect of the blast decreasesextremely rapidly as the distance from the nozzle in-creases. In addition, the recirculation fan absorbs energy and, at the same time, imparts heat energy to the recirculating gas~
~i, ~ ' .. _ ~ 21199~
, .~ , It will be appreciated that it is impractical to install fans in the rotatable drum because of the rota-tion of the drum, the risk of damage from and to the product and the low temperatures present.
SUMMARY OF THE INVENTION
~" According to the present invention there is provi-ded a rotary tunnel freezer comprising a drum which, in ~` use, is rotatable about its longitudinal axis, and means for introducing a cryogen into an end of said drum, wherein said drum is provided with a plurality of noz-zles arranged at intervals along a major portion of the length (F) of said drum for introducing cryogenic fluid into said drum and stirring the atmosphere therein.
Advantagèously, said means for introducing cryogen into said end of said drum comprises a spray header and said plurality of nozzles are disposed on an extension thereof.
Advantageously, said nozzles for stirring the atmo-sphere are disposed to introduce cryogen into said drum substantially tangentially thereof and, preferably, closely adjacent the radially inner surface of the drum.
Conveniently, the nozzles for stirring the atmo-sphere are disposed on generally outwardly extending ~i, extensions emanating from a common supply bar.
Typically, said nozzles for stirring the atmosphere are disposed at centres of from 250mm to 750mm, prefer-ably from 400mm to 600mm, and advantageously at 500mm centres.
Preferably, said nozzles for stirring the atmo-sphere are disposed over at least 70% of the overall length of the tunnel, more preferably over at least 85~, and advantageously over that part of the drum which is -~ not occupied by the spray header.
Typically, the spray header will comprise a plural-~,~ ity of nozzles separated at 25mm - 50mm centres. The ,~ ~
r- _,~
_ 3 _ 2 1 1 ~ 9 ~ ~
output of the nozzles in the spray header and the noz-- zles for stirring the atmosphere may be the same for a given pressure or may differ. Typically, The nozzles in - the spray header will have an outlet diameter of from 1.5mm to 3.Omm whilst the nozzles for stirring the atmosphere may have an outlet diameter less than or equal to lmm.
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For a better understanding of the present inven-tion, and to show how the same may be carried into ;- effect, reference will now be made, by way of example, to the accompanying drawing which shows a schematic perspective view, with part cut away, of a rotary tunnel freezer in accordance with the invention.
~`. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
~,; Referring to the drawing, there is shown a rotary tunnel freezer which is generally identified by refer-ence numeral 1.
The rotary tunnel freezer 1 comprises a drum 2 which is mounted for rotation about its longitudinal axis on rollers 3. A belt 4 extends around the drum 2 and around the drive shaft of an electric motor 5.
A spray header 6 connected to a supply of liquid nitrogen (not shown) is mounted in the inlet section 7 of the drum 2 and extends a distance equal to approxima-tely 15% of the overall length 'F' of the drum. The spray header 6 is provided with a plurality of nozzles ~`~ 20 with outlets 2mm in diameter positioned at 50mm centres.
An inlet tray 8 slopes gently downwardly into the inlet section of the drum 2 which is itself inclined downwardly at an angle of about 3 to the horizontal.
~ The inlet section 7 is provided with a helical fin which ,- 25 defines a plurality of weirs.
At the commencement of a freezing operation motor 5 is actuated to rotate the drum 2, which typically has an ~- external diameter D of from 1.25m to 1.6m at from 1 to 5 rpm.
~, 30 A valve (not shown) is then opened at allow liquid nitrogen to spray downwardly from the spray header 6 into the inlet section 7.
As the drum 2 cools down pools of liquid nitrogen ~; form in the inlet section 7 whilst the gaseous nitrogen ;~
rolls down and cools the remainder of the drum 2.
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~, Once the temperature at the downstream end 9 of the ~ drum 2 reaches the desired level a control system (not '` shown) adjusts the supply of liquid nitrogen as re-'~ quired.
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Product to be frozen, for example particles of food to be individually quick-frozen is then introduced into the inlet section 7 via inlet tray 8. The product falls into the liquid ni~rogen in the weirs and a frozen crust forms within a few seconds. Because of the nature of immersion freezing the individual particles do not tend to stick together.
`~ As the drum 2 rotates the product passes slowly ~- down the drum 2 during which time it freezes throughout.
~- The throughput of the rotary tunnel freezer is largely determined by the time which the product must stay in the freezer, which is itself determined by the '~ rate of heat transfer from the liquid and gaseous nitro-gen to the product.
The arrangement thus far described is also de-scribed in our European Patent Publication No.
0 372 354.
., In order to increase the rate of heat transfer the drum is provided with stlrring means which comprise nozzles 10 mounted on arms 11 which extend outwardly from a tube 12 which communicates with the downstream end 13 of the spray header 6.
~-~In use, in addition to being sprayed downwardly ~`onto the inlet section 7, nitrogen is ejected from the nozzles 10 which have an outlet diameter of 0.75mm.
*: .
~-` 30 Nitrogen expands by approximately 700 times when chan-~-~ ging from liquid to vapour and this expansion vigorously stirs the surrounding atmosphere in the drum thereby greatly enhancing the heat transfer.
-The nitrogen may be ejected from the nozzle 10 as ~35 liquid for maximum cooling. However, where it is desir-., .
., .
21199~
able to avoid over-cooling, a valve (not shown) is pre-ferably disposed between the spray header 6 and the tube 12 to limit the flow of liquid nitrogen and to enable it to vaporise in the tube 12 and leave the nozzles 10 as cold vapour.
The nozzles 10 are positioned at 500mm centres and are positioned to introduce nitrogen substantially tangentially to the drum 2 approximately 10 cms from the inside of the drum 2.
~ .
Initial trials have been extremely encouraging and ~- we have found that at product rates where previously ~ product was not frozen throughout on leaving the drum 2, `~ freezing is now complete.
Various modifications to the embodiment described are envisaged, for example whilst the nozzles 10 are preferably simple spray nozzles they could also comprise air movers. However, this alternative is not recommended because of the additional expense.
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For a better understanding of the present inven-tion, and to show how the same may be carried into ;- effect, reference will now be made, by way of example, to the accompanying drawing which shows a schematic perspective view, with part cut away, of a rotary tunnel freezer in accordance with the invention.
~`. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
~,; Referring to the drawing, there is shown a rotary tunnel freezer which is generally identified by refer-ence numeral 1.
The rotary tunnel freezer 1 comprises a drum 2 which is mounted for rotation about its longitudinal axis on rollers 3. A belt 4 extends around the drum 2 and around the drive shaft of an electric motor 5.
A spray header 6 connected to a supply of liquid nitrogen (not shown) is mounted in the inlet section 7 of the drum 2 and extends a distance equal to approxima-tely 15% of the overall length 'F' of the drum. The spray header 6 is provided with a plurality of nozzles ~`~ 20 with outlets 2mm in diameter positioned at 50mm centres.
An inlet tray 8 slopes gently downwardly into the inlet section of the drum 2 which is itself inclined downwardly at an angle of about 3 to the horizontal.
~ The inlet section 7 is provided with a helical fin which ,- 25 defines a plurality of weirs.
At the commencement of a freezing operation motor 5 is actuated to rotate the drum 2, which typically has an ~- external diameter D of from 1.25m to 1.6m at from 1 to 5 rpm.
~, 30 A valve (not shown) is then opened at allow liquid nitrogen to spray downwardly from the spray header 6 into the inlet section 7.
As the drum 2 cools down pools of liquid nitrogen ~; form in the inlet section 7 whilst the gaseous nitrogen ;~
rolls down and cools the remainder of the drum 2.
,~'~ ..
.: ~
21199~
~, Once the temperature at the downstream end 9 of the ~ drum 2 reaches the desired level a control system (not '` shown) adjusts the supply of liquid nitrogen as re-'~ quired.
r:
Product to be frozen, for example particles of food to be individually quick-frozen is then introduced into the inlet section 7 via inlet tray 8. The product falls into the liquid ni~rogen in the weirs and a frozen crust forms within a few seconds. Because of the nature of immersion freezing the individual particles do not tend to stick together.
`~ As the drum 2 rotates the product passes slowly ~- down the drum 2 during which time it freezes throughout.
~- The throughput of the rotary tunnel freezer is largely determined by the time which the product must stay in the freezer, which is itself determined by the '~ rate of heat transfer from the liquid and gaseous nitro-gen to the product.
The arrangement thus far described is also de-scribed in our European Patent Publication No.
0 372 354.
., In order to increase the rate of heat transfer the drum is provided with stlrring means which comprise nozzles 10 mounted on arms 11 which extend outwardly from a tube 12 which communicates with the downstream end 13 of the spray header 6.
~-~In use, in addition to being sprayed downwardly ~`onto the inlet section 7, nitrogen is ejected from the nozzles 10 which have an outlet diameter of 0.75mm.
*: .
~-` 30 Nitrogen expands by approximately 700 times when chan-~-~ ging from liquid to vapour and this expansion vigorously stirs the surrounding atmosphere in the drum thereby greatly enhancing the heat transfer.
-The nitrogen may be ejected from the nozzle 10 as ~35 liquid for maximum cooling. However, where it is desir-., .
., .
21199~
able to avoid over-cooling, a valve (not shown) is pre-ferably disposed between the spray header 6 and the tube 12 to limit the flow of liquid nitrogen and to enable it to vaporise in the tube 12 and leave the nozzles 10 as cold vapour.
The nozzles 10 are positioned at 500mm centres and are positioned to introduce nitrogen substantially tangentially to the drum 2 approximately 10 cms from the inside of the drum 2.
~ .
Initial trials have been extremely encouraging and ~- we have found that at product rates where previously ~ product was not frozen throughout on leaving the drum 2, `~ freezing is now complete.
Various modifications to the embodiment described are envisaged, for example whilst the nozzles 10 are preferably simple spray nozzles they could also comprise air movers. However, this alternative is not recommended because of the additional expense.
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Claims (20)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A rotary tunnel freezer comprising a drum which is mounted for rotation about its longitudinal axis, and means for introducing a cryogen into an end of said drum, wherein said drum is provided with a plurality of nozzles arranged at intervals along a major portion of the length of said drum for introducing cryogenic fluid into said drum and stirring the atmosphere therein.
2. A rotary tunnel freezer as claimed in Claim 1, wherein said means for introducing cryogenic fluid into said end of said drum comprises a spray header, and said plurality of nozzles are disposed on an extension there-of.
3. A rotary tunnel freezer as claimed in Claim 2, wherein the diameter of the output of the nozzles for stirring the atmosphere in said drum is not greater than lmm.
4. A rotary tunnel freezer as claimed in Claim 1, wherein said nozzles for stirring said atmosphere are disposed to introduce cryogen into said drum substanti-ally tangentially thereof.
5. A rotary tunnel freezer as claimed in Claim 1, wherein said nozzles for stirring said atmosphere are disposed to introduce cryogen into said drum closely adjacent the inner surface thereof.
6. A rotary tunnel freezer as claimed in Claim 1, wherein said nozzles for stirring said atmosphere are disposed on generally outwardly extending extensions from a common supply bar.
7. A rotary tunnel freezer as claimed in Claim 1, wherein said nozzles for stirring said atmosphere are disposed at centres of from 250mm to 750mm.
8. A rotary tunnel freezer as claimed in Claim 1, wherein said nozzles for stirring said atmosphere are disposed over at least 70% of the overall length of said drum.
9. A rotary tunnel freezer comprising a drum which is mounted for rotation about its longitudinal axis, and means for introducing a cryogen into an end of said drum, wherein said drum is provided with a plurality of nozzles arranged at intervals along a major portion of the length of said drum for introducing cryogenic fluid into said drum and stirring the atmosphere therein, wherein said nozzles are disposed on generally outwardly extending extensions from a common supply bar and are disposed closely adjacent the inner surface of said drum.
10. A rotary tunnel freezer as claimed in Claim 9, wherein said means for introducing cryogenic fluid into said end of said drum comprises a spray header, and said common supply bar comprises an extension of said spray header.
11. a rotary tunnel as claimed in Claim 9, wherein said nozzles open substantially tangentially to the inside of said drum.
11. a rotary tunnel as claimed in Claim 9, wherein said nozzles open substantially tangentially to the inside of said drum.
11. A rotary tunnel freezer as claimed in Claim 9, wherein the diameter of the output of the nozzles for stirring the atmosphere in said drum is less than or equal to lmm.
12. A rotary tunnel freezer as claimed in Claim 9, wherein said nozzles for stirring said atmosphere are disposed at centres of from 250mm to 750mm.
13. A rotary tunnel freezer as claimed in Claim 9, wherein said nozzles for stirring said atmosphere are disposed over at least 70% of the overall length of said drum.
14. A rotary tunnel freezer comprising a drum which is mounted for rotation about its longitudinal axis, and means for introducing a cryogen into an end of said drum, wherein said drum is provided with a plurality of nozzles arranged at intervals along a major portion of the length of said drum for introducing cryogenic fluid into said drum and stirring the atmosphere therein, wherein said means for introducing cryogenic fluid into said end of said drum comprises a spray header, and said plurality of nozzles are disposed on an extension there-of.
15. A rotary tunnel freezer as claimed in Claim 14, wherein the diameter of the output of the nozzles for stirring the atmosphere in said drum is less than or equal to lmm.
16. A rotary tunnel freezer as claimed in Claim 14, wherein said nozzles for stirring said atmosphere are disposed to introduce cryogen into said drum substanti-ally tangentially thereof.
17. A rotary tunnel freezer as claimed in Claim 16, wherein said nozzles for stirring said atmosphere are disposed to introduce cryogen into said drum closely adjacent the inner surface thereof.
18. A rotary tunnel freezer as claimed in Claim 17, wherein said nozzles for stirring said atmosphere are disposed on generally outwardly extending extensions from a common supply bar.
19. A rotary tunnel freezer as claimed in Claim 18, wherein said nozzles for stirring said atmosphere are disposed at centres of from 250mm to 750mm.
20. A rotary tunnel freezer as claimed in Claim 19, wherein said nozzles for stirring said atmosphere are disposed over at least 70% of the overall length of said drum.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9306285.9 | 1993-03-26 | ||
| GB939306285A GB9306285D0 (en) | 1993-03-26 | 1993-03-26 | Rotary tunnel freezer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2119994A1 true CA2119994A1 (en) | 1994-09-27 |
Family
ID=10732781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002119994A Abandoned CA2119994A1 (en) | 1993-03-26 | 1994-03-25 | Rotary tunnel freezer |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA2119994A1 (en) |
| DE (1) | DE4410503A1 (en) |
| GB (2) | GB9306285D0 (en) |
| ZA (1) | ZA942132B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1286442B1 (en) * | 1996-12-05 | 1998-07-08 | Pugnale S R L | APPARATUS FOR CONTINUOUS FREEZING OF FOOD PRODUCTS |
| FR2766738B1 (en) * | 1997-08-01 | 1999-09-03 | Air Liquide | METHOD AND DEVICE FOR SEQUENTIALLY SPRAYING A CRYOGENIC LIQUID, METHOD AND INSTALLATION FOR COOLING THEREOF |
| US6895775B2 (en) * | 2002-08-16 | 2005-05-24 | The Boc Group, Inc. | Apparatus for surface crust freezing of food product |
| CN107883631A (en) * | 2017-12-12 | 2018-04-06 | 广州鲜之源生态冷链技术有限公司 | A kind of multinode temperature control device and regulation and control method |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3906743A (en) * | 1973-05-30 | 1975-09-23 | Union Corp | Refrigeration apparatus having a rotatable drum |
| FR2588067B1 (en) * | 1985-10-02 | 1988-05-13 | Air Liquide | METHOD AND TUNNEL FOR SURFACE COOLING OF FOOD PRODUCTS |
| DE8608538U1 (en) * | 1986-03-27 | 1988-02-18 | Messer Griesheim Gmbh, 6000 Frankfurt | Device for freezing food on a trolley |
| GB2225846A (en) * | 1988-12-09 | 1990-06-13 | Air Prod & Chem | Tunnel freezer |
-
1993
- 1993-03-26 GB GB939306285A patent/GB9306285D0/en active Pending
-
1994
- 1994-03-25 GB GB9405995A patent/GB2276440A/en not_active Withdrawn
- 1994-03-25 DE DE4410503A patent/DE4410503A1/en not_active Withdrawn
- 1994-03-25 ZA ZA942132A patent/ZA942132B/en unknown
- 1994-03-25 CA CA002119994A patent/CA2119994A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| DE4410503A1 (en) | 1994-09-29 |
| GB2276440A (en) | 1994-09-28 |
| GB9306285D0 (en) | 1993-05-19 |
| ZA942132B (en) | 1995-09-26 |
| GB9405995D0 (en) | 1994-05-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 19960925 |