GB2163637A - Removal of ethylene from fruit and vegetables stores by catalytic combustion - Google Patents
Removal of ethylene from fruit and vegetables stores by catalytic combustion Download PDFInfo
- Publication number
- GB2163637A GB2163637A GB08422076A GB8422076A GB2163637A GB 2163637 A GB2163637 A GB 2163637A GB 08422076 A GB08422076 A GB 08422076A GB 8422076 A GB8422076 A GB 8422076A GB 2163637 A GB2163637 A GB 2163637A
- Authority
- GB
- United Kingdom
- Prior art keywords
- air
- store
- heat exchange
- ethylene
- exchange means
- 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.)
- Withdrawn
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Classifications
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B7/00—Preservation or chemical ripening of fruit or vegetables
- A23B7/14—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10
- A23B7/144—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor
- A23B7/148—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
-
- A—HUMAN NECESSITIES
- A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
- A23B—PRESERVING, e.g. BY CANNING, MEAT, FISH, EGGS, FRUIT, VEGETABLES, EDIBLE SEEDS; CHEMICAL RIPENING OF FRUIT OR VEGETABLES; THE PRESERVED, RIPENED, OR CANNED PRODUCTS
- A23B7/00—Preservation or chemical ripening of fruit or vegetables
- A23B7/14—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10
- A23B7/144—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor
- A23B7/152—Preserving or ripening with chemicals not covered by groups A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere comprising other gases in addition to CO2, N2, O2 or H2O ; Elimination of such other gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8668—Removing organic compounds not provided for in B01D53/8603 - B01D53/8665
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Polymers & Plastics (AREA)
- Zoology (AREA)
- Food Science & Technology (AREA)
- Wood Science & Technology (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Biomedical Technology (AREA)
- Analytical Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Gas Burners (AREA)
- Storage Of Fruits Or Vegetables (AREA)
Abstract
The removal of ethylene from the atmosphere in a fruit and vegetable store by withdrawing air from the store, passing it through one or more heat exchangers comprising heat pipes mounted in a supporting sandwich consisting of two metal plates spaced apart by a layer of resilient synthetic polymeric material, then passing the air at 200 DEG C through a catalytic combustor in which the catalyst is deposited on a channelled support and returning the air to the store via the heat exchangers. Use of these particular heat exchangers in combination with the channelled support enables ethylene concentrations of below 50 ppb to be achieved.
Description
SPECIFICATION
Removal of ethylene from fruit and vegetable stores by catalytic combustion
This invention relates to a process for the removal of ethylene from fruit and vegetable stores by catalytic combustion.
Stored fruit and vegetables emit ethylene which accelerates the rotting process if it is allowed to remain in the atmosphere of the store in significant quantities. United States patent specification 4 331 693 (the contents of which are herein incorporated by reference) discloses a process for removing ethylene from the atmosphere in a store by taking air from the store, heating it by means of an electrical heater to at least 2000C and passing it through a catalytic combustor before returning it to the store. Ethylene is removed by catalytic combustion and the air returned to the store contains an ethylene concentration which has been reduced to about 1 part per million (ppm).An object of this invention is to provide an improved process which can deal with ethylene concentrations of less than 50 parts per billion (ppb where b is 109) whilst retaining a catalyst efficiency of at least 50%, that is to say not less than 50% by volume of the ethylene entering the combustor undergoes catalytic combustion. Catalyst efficiency is more difficult to maintain when the concentration of ethylene in the air entering the combustor falls below 1 ppm.
Accordingly this invention provides a process for the removal of ethylene from a fruit or vegetable store using catalytic combustion which comprises
a) withdrawing ethylene-containing air at a temperature of below 500C from the store,
b) passing the air through heating means which comprises heat exchange means and which raises the temperature of the air to at least 200 C, c) then passing the heated air through a catalytic combustor and
d) returning air from the combustor back to the store via the heat exchange means so that it can heat air being withdrawn from the store wherein the heat exchange means comprises a plurality of heat pipes which make a fluid-tight fit in and project either side of a supporting sandwich which comprises a pair of metal members spaced apart by a layer of resilient polymeric material and the catalytic combustor comprises a catalyst containing at least one of the metals platinum, palladium, ruthenium or rhodium deposited on activated aluminium (preferably -alumina) which in turn is supported on walls defining channels in a support through which air from the store is caused to flow. Preferably the heat exchange means reduces the temperature of the returning air to below 500C before it re-enters the store.
It has been found that by combining the use of a channelled support for the catalyst with a heat exchange means comprising heat pipes mounted in a metal/plastics sandwich enables the ethylene concentration in the withdrawn air to be reduced to levels below 50 ppb whilst retaining the ability of the catalytic combustor to operate at efficiencies of not less than 50%.
The invention is further illustrated by the following preferred embodiment which is described with reference to the drawings of which
Figure 1 is a flow sheet showing the relative positioning of a store, heat exchange means and catalytic combustor,
Figure 2 is a section through a heat exchange means,
Figure 3 is a perspective view of a channelled support, and
Figure 4 is a section through a channelled support (shown diagrammatically) located in a catalytic combustor.
Figure 1 shows a store 1 from which air is withdrawn by the action of fan 2 and passed into a first heat exchange means 3 shown in more detail in Figure 2. The withdrawn air is heated and then passed via fan 2 into heat exchange means 4 (also shown in Figure 2) where it undergoes further heating. The withdrawn air is then passed into electrical heater 5 where it is heated to 2000C and passed into catalytic combustor 6 containing channelled support 7. The air passes through channels 8 of support 7 where catalytic combustion of most of the ethylene content of the air occurs. Combustor 6, support 7 and channels 8 are shown in more detail in Figures 3 and 4. Air leaving combustor 6 is returned to store 1 via heat exchange means 4 and 3 where it is used to heat the withdrawn air.
Figure 2 shows heat exchange means 3 and 4 in greater detail. Heat exchange means 3 and 4 comprise a metal housing 9 in which is mounted a horizontal supporting sandwich 10 comprising opposed steel plates 10a and 10b spaced apart by a layer 10c of resilient synthetic polymeric material. Sandwich 10 supports vertical heat pipes 11 which pass through sandwich 10 in which they make an air-tight fit and project either side above and below sandwich 10. Heat pipes 11 contain water as their heat exchange fluid. Housing 9 contains inlets 12a and 13a and outlets 12b and 13b to enable air withdrawn from store 1 and air returning to store 1 to flow through housing 9 and contact heat pipes 11. Heat pipes 11 are provided with transverse heat conducting aluminium fins 14 to facilitate heat exchange between the air and heat pipes 11.
Figure 3 shows channelled support 7 in more detail and in particular it shows channels 8 defined by horizontal and vertical walls 8a and 8b. Figure 4 shows catalytic combustor 6 which comprises a housing 15 containing support 7 and inlet and outlet 15a and 15b for enabling air to be passed through channels 8' and into contact with the catalyst which initiates catalytic combustion.
The embodiment illustrated in figures 1 to 4 may be modified by the use of only one or more than two heat exchange means depending on the temperature of the air withdrawn from the store. Preferably the heat exchange means comprise from 1 to 4 separate heat exchange units. It is preferred to use at least one external heat source (such as an electrical heater) to heat the withdrawn air up to 2000C because the air returning from the catalytic combustor is seldom hot enough to do this reliably.
It should be explained that a heat pipe is a pipe closed at both ends and containing a liquid (usually water) and having one end disposed below the other so that the liquid accumulates in the lower end. The lower end is exposed to a hotter medium and the upper end is exposed to a cooler medium. The hotter medium causes the liquid to evaporate and rise to the upper end of the heat tube where it condenses thereby heating the cooler medium. The heat pipes used in this invention are preferably cylindrical and from 1 to 5 mm in diameter and they preferably project from 100 to 500 mm from the supporting sandwich. The metal members of the sandwich are preferably 2 to 10 mm thick as is the layer of resilient synthetic polymeric material. The polymeric material may be any suitably temperature resistant material such as resilient epoxy resin, polyurethane, crosslinked polyethylene or nylon.
The channelled support may be made from metal or from a ceramic material. The channels are most conveniently square in crosssection and have a cross-sectional area of preferably 0.2 to 0.6 mm. The preferred catalyst is platinum.
The invention is further illustrated by the following Example.
Example
The embodiment described with reference to figures 1 to 4 of the drawings was used to remove ethylene from the atmosphere in an apple store. Air containing 34 ppm ethylene and at a temperature of 30C was withdrawn from the store at a rate of 150M3/hr. It was heated from 3 to 660C by the first heat exchange means and from 66 to 1 930C by the second. Heating from 193 to 2000C was performed by the electrical heater and then the air was passed through the catalytic combustor. Air returning from the combustor was cooled from 200 to 730C by the second heat exchange means and from 73 to 10 C by the first. It was returned to the store at 10 C.
The catalyst in the combustor was platinum deposited on -alumina.
It was found that the ethylene concentration in the air re-entering the store was from 15 to 20 ppb and that the operating efficiency of the catalytic combustor was 60%. This meant that the ethylene removal process could achieve ethylene concentrations of well below 50 ppb without needing to be operated continuously throughout the day. 1.A process for the removal of ethylene from a fruit or vegetable store using catalytic combustion which comprises
a) withdrawing ethylene-containing air at a temperature of below 500C from the store,
b) passing the air through heating means which comprises heat exchange means and which raises the temperature of the air to at least 200 C, c) then passing the heated air through a catalytic combustor and
d) returning air from the combustor back to the store via the heat exchange means so that it can heat air being withdrawn from the store wherein the heat exchange means comprises a plurality of heat pipes which make a fluid-tight fit in and project either side of a supporting sandwich which comprises a pair of metal members spaced apart by a layer of resilient polymeric material and the catalytic combustor comprises a catalyst containing at least one of the metals platinum, palladium, ruthenium or rhodium deposited on activated aluminium which in turn is supported on walls defining channels in a support through which air from the store is caused to flow.
2. A process according to claim 1 wherein the heat exchange means comprises from 1 to 4 heat exchange units.
3. A process according to claim 1 or claim 2 wherein the heat exchange means reduces the temperature of the returning air to below 500C before it re-enters the store.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (3)
- **WARNING** start of CLMS field may overlap end of DESC **.enabling air to be passed through channels 8' and into contact with the catalyst which initiates catalytic combustion.The embodiment illustrated in figures 1 to 4 may be modified by the use of only one or more than two heat exchange means depending on the temperature of the air withdrawn from the store. Preferably the heat exchange means comprise from 1 to 4 separate heat exchange units. It is preferred to use at least one external heat source (such as an electrical heater) to heat the withdrawn air up to 2000C because the air returning from the catalytic combustor is seldom hot enough to do this reliably.It should be explained that a heat pipe is a pipe closed at both ends and containing a liquid (usually water) and having one end disposed below the other so that the liquid accumulates in the lower end. The lower end is exposed to a hotter medium and the upper end is exposed to a cooler medium. The hotter medium causes the liquid to evaporate and rise to the upper end of the heat tube where it condenses thereby heating the cooler medium. The heat pipes used in this invention are preferably cylindrical and from 1 to 5 mm in diameter and they preferably project from 100 to 500 mm from the supporting sandwich. The metal members of the sandwich are preferably 2 to 10 mm thick as is the layer of resilient synthetic polymeric material. The polymeric material may be any suitably temperature resistant material such as resilient epoxy resin, polyurethane, crosslinked polyethylene or nylon.The channelled support may be made from metal or from a ceramic material. The channels are most conveniently square in crosssection and have a cross-sectional area of preferably 0.2 to 0.6 mm. The preferred catalyst is platinum.The invention is further illustrated by the following Example.Example The embodiment described with reference to figures 1 to 4 of the drawings was used to remove ethylene from the atmosphere in an apple store. Air containing 34 ppm ethylene and at a temperature of 30C was withdrawn from the store at a rate of 150M3/hr. It was heated from 3 to 660C by the first heat exchange means and from 66 to 1 930C by the second. Heating from 193 to 2000C was performed by the electrical heater and then the air was passed through the catalytic combustor. Air returning from the combustor was cooled from 200 to 730C by the second heat exchange means and from 73 to 10 C by the first. It was returned to the store at 10 C.The catalyst in the combustor was platinum deposited on -alumina.It was found that the ethylene concentration in the air re-entering the store was from 15 to 20 ppb and that the operating efficiency of the catalytic combustor was 60%. This meant that the ethylene removal process could achieve ethylene concentrations of well below 50 ppb without needing to be operated continuously throughout the day. 1.A process for the removal of ethylene from a fruit or vegetable store using catalytic combustion which comprises a) withdrawing ethylene-containing air at a temperature of below 500C from the store, b) passing the air through heating means which comprises heat exchange means and which raises the temperature of the air to at least 200 C,c) then passing the heated air through a catalytic combustor and d) returning air from the combustor back to the store via the heat exchange means so that it can heat air being withdrawn from the store wherein the heat exchange means comprises a plurality of heat pipes which make a fluid-tight fit in and project either side of a supporting sandwich which comprises a pair of metal members spaced apart by a layer of resilient polymeric material and the catalytic combustor comprises a catalyst containing at least one of the metals platinum, palladium, ruthenium or rhodium deposited on activated aluminium which in turn is supported on walls defining channels in a support through which air from the store is caused to flow.
- 2. A process according to claim 1 wherein the heat exchange means comprises from 1 to 4 heat exchange units.
- 3. A process according to claim 1 or claim 2 wherein the heat exchange means reduces the temperature of the returning air to below 500C before it re-enters the store.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08422076A GB2163637A (en) | 1984-08-31 | 1984-08-31 | Removal of ethylene from fruit and vegetables stores by catalytic combustion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08422076A GB2163637A (en) | 1984-08-31 | 1984-08-31 | Removal of ethylene from fruit and vegetables stores by catalytic combustion |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8422076D0 GB8422076D0 (en) | 1984-10-03 |
| GB2163637A true GB2163637A (en) | 1986-03-05 |
Family
ID=10566103
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08422076A Withdrawn GB2163637A (en) | 1984-08-31 | 1984-08-31 | Removal of ethylene from fruit and vegetables stores by catalytic combustion |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2163637A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2640889A1 (en) * | 1988-12-26 | 1990-06-29 | Toulouse Inst Nat Polytech | Process and device for catalytic purification of the atmosphere of an enclosure for storing plants |
| EP0397856A1 (en) * | 1988-11-23 | 1990-11-22 | The Governors of the University of Alberta | Method and apparatus for purifying air |
| GB2394882A (en) * | 2003-04-05 | 2004-05-12 | Greenvale Ap Ltd | Controlling sprout growth in a root vegetable |
| EP2210498A1 (en) | 2005-11-01 | 2010-07-28 | Johnson Matthey Public Limited Company | Adsorption of volatile organic compounds derived from organic matter |
| WO2011001186A1 (en) | 2009-07-02 | 2011-01-06 | Johnson Matthey Plc | Absorption of volatile organic compounds derived from organic matter |
| US11065579B2 (en) | 2016-09-16 | 2021-07-20 | James SAWADA | Catalytic combustion in low temperature, humid conditions |
-
1984
- 1984-08-31 GB GB08422076A patent/GB2163637A/en not_active Withdrawn
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0397856A1 (en) * | 1988-11-23 | 1990-11-22 | The Governors of the University of Alberta | Method and apparatus for purifying air |
| EP0397856A4 (en) * | 1988-11-23 | 1991-05-15 | Univ Alberta | Method and apparatus for purifying air |
| FR2640889A1 (en) * | 1988-12-26 | 1990-06-29 | Toulouse Inst Nat Polytech | Process and device for catalytic purification of the atmosphere of an enclosure for storing plants |
| GB2394882A (en) * | 2003-04-05 | 2004-05-12 | Greenvale Ap Ltd | Controlling sprout growth in a root vegetable |
| GB2394882B (en) * | 2003-04-05 | 2004-11-10 | Greenvale Ap Ltd | Method for controlling sprout growth in a root vegetable |
| US8480794B2 (en) | 2005-11-01 | 2013-07-09 | Johnson Matthey Public Limited Company | Adsorption of volatile organic compounds derived from organic matter |
| US7910773B2 (en) | 2005-11-01 | 2011-03-22 | Johnson Matthey Public Limited Company | Adsorption of volatile organic compounds derived from organic matter |
| USRE44125E1 (en) | 2005-11-01 | 2013-04-02 | Johnson Matthey Public Limited Company | Adsorption of volatile organic compounds derived from organic matter |
| EP2210498A1 (en) | 2005-11-01 | 2010-07-28 | Johnson Matthey Public Limited Company | Adsorption of volatile organic compounds derived from organic matter |
| US9186649B2 (en) | 2005-11-01 | 2015-11-17 | Anglo Platinum Marketing Limited | Adsorption of volatile organic compounds derived from organic matter |
| WO2011001186A1 (en) | 2009-07-02 | 2011-01-06 | Johnson Matthey Plc | Absorption of volatile organic compounds derived from organic matter |
| US8900348B2 (en) | 2009-07-02 | 2014-12-02 | Johnson Matthey Public Limited Company | Adsorption of volatile organic compounds derived from organic matter |
| US11065579B2 (en) | 2016-09-16 | 2021-07-20 | James SAWADA | Catalytic combustion in low temperature, humid conditions |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8422076D0 (en) | 1984-10-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |