GB2313381A

GB2313381A - Charcoal covered by a film

Info

Publication number: GB2313381A
Application number: GB9709448A
Authority: GB
Inventors: Alain Legros
Original assignee: RETINA INT BV
Current assignee: RETINA INT BV
Priority date: 1996-05-24
Filing date: 1997-05-10
Publication date: 1997-11-26
Also published as: DE19721507A1; FR2749020B3; FR2749020A3; BE1010304A5; GB9709448D0

Description

2313381 Charcoal This invention relates to a charcoal modified by an

agent.

Charcoal is a fuel used in barbecues for private or professional purposes.

Charcoal presents certain inconveniences, of which the major ones are the formation olL dusts and the dirty character of charcoal. Charcoal dusts can settle on the lo walls of the barbecue or can be carried by the wind or the smoke, with a risk of dust deposits being carried on to plates, on to food etc.

This invention aims at remedying these inconveniences.

The charcoal according to the invention has an outer surface which is at least partially covered by means of at least one layer of a film-forming material, said layer comprising at least, on the one hand, a compound selected from the group consisting of cellulose, a cellulose derivative, starch, starch derivative and mixture thereof, and, on the other hand, a compound selected from among the sodium chloride, magnesium chloride, calcium chloride, potassium chloride and their mixtures.

Particular examples of film-forming compounds or materials are: polysaccharides(cellulose, starch, methylcellulose) with a molecular weight greater than 1,000, for example comprised between 2,500 and 10,000.

According to an embodiment, the layer at least partially covering the outer surface of the charcoal further contains a compound selected from the group consisting of calcium and/or magnesium hydroxide, carbonate or bicarbonate.

Advantageously, the porosity of the charcoal is modified by the layer, in such a way that the layer at least partially covering the outer surface of the charcoal 2 closes at least 25% of the pores of the charcoal, i.e. closes the outer openings of pores corresponding to at 1 east 25% of the total porosity. Preferably, at least 50% of the pores of the charcoal are closed. However, it is advantageous that the said -layer does not close all the pores of the charcoal. For example, 10% to 20% of the pores (corresponding to 10 to 20% of the porosity) are not closed.

The charcoal has preferably a water content from 3 to 10% in weight. This percentage could possibly be less. it has nevertheless been noted that charcoal according to the invention having a water conten t near to 10% in weight would always permit a good combustion..

The size of the charcoal is for example greater than 1-Omm, for example comprised between 1Omm and 50mm or more.

owing to this closure or obstruction of the pores, the CC possibly formed at the heart of the charcoal would only be able to spread to the outside through the obstructed pore after destruction or combustion of - the layer, in other words once the superficial temperature'of the charcoal has reached a considerable or high temperature. In view of this high superficial temperature,- the CO possibly escaping out of the charcoal is immediately converted into C02.

Utilisation of the outer layer on the charcoal enables the formation of dusts to be reduced and the Aet-achment of superficial particles or dusts from the charcoal to be reduced before and at the start of combustion of the charcoal. Indeed, the layer is preferably such t.n-zt the detachment of superficial dusts from the charcoal is only perceptibly possible when the start of the ignition temperature is reached. Such dusts which would then be detached or carried by the smoke would then be quickly burned.

The layer according to the invention enables the 3 ignition temperature of the charcoal to be controlled. For example the presence of- the external layer enables the self-ignition temperature of the charcoal to be increased or the formation of flames to be reduced, for example when 5 a critical temperature is reached.

The invention also relates to a method for.ianufacturing charcoal according to the invention, in which -he charcoal is treated by means of a solutioh or suspension containing on the one hand,- a compound selected from the group consisting of cellulose, a cellulose derivative, starch, starch derivative and mixtures thereof, and, on the other hand, a compound selected from among the sodium chloride, magnesium chloride, calcium chloride,,-)otassium chloride and their mixtures.

Advantageously, the charcoal is treated by means of an aqueous solution containing, on the one hand, a compound selected from the group consisting of cellulose a cellulose derivative, starch, starch derivative and mixtures thereof, and on the other hand, a compound selected from among the sodium chloride, magnesium chloride, calcium chloride, potassium chloride and their mixtures.

According to an embodiment, the charcoal is soaked in an aqueous solution containing, on the one hand, a compound selected from the group consisting of _cellulose -a cellulose derivative, starch, starch derivative and mixtures thereof, and on the other hand, a compound selected from among the sodium chloride, magnesium chloride, calcium chloride, potassium chloride and their mixtures.

According t- o a preferred embodiment, an aqueous solution containing, on the one hand, a compound selected the group consisting of cellulose a cellulose derivative, starch, starch derivative and mixtures thereof, 4 and, on the other hand, a compound selected from among the sodium chloride,. magnesium chloride, calcium chloride, notassium chloride and their mixtures is sprayed on to the charcoal.

5. Advantageously, the charcoal after its treatment by means of the soluzion or suspension is subjected to a drying step.

According to preferred embodiment, the aqueous solution contains on the one hand, from 0.01 to 1%, preferably from 0.05 to 0.5% by weight of a compound selected from the group consisting of cellulose a cellulose derivative, starch, starch derivative and mixture thereof, and -, on the other hand, from 0.1 to 5%, preferably from 0.5 to 2% by weight of a compound selected from' among the sodium chloride, magnesium chloride, calcium chloriae, potassium chloride and their mixtures.

Preferably, the aqueous solution is sprayed on hot charcoal, for example on charcoal having a temperature higher than 70-OC, for example charcoal leaving the burning step.

Another object of the invention is an installation for the production of charcoal according to the invention.

This instal--ation" comprises a conveyor belt for moving the charcoal and a device for spraying, fogging or atomising the aqueous,,lution on to the charcoal, or a conveyor belt for moving the charcoal into a bath containing the aqueous solution and for removing the treated charcoal from the aforementioned bath, or a conveyor belt for moving the charcoal to a unit comprising one or several rollers suited for releasing the aqueous solution on to the charcoal, the roller advantageously comprising a porous and elastic covering or outer layer (for example of the type of synthetic foam with open pores or sponge).

The characteristics -and details of the invention will become apparent from the following description of examples of the embodiment.

Example 1

An aqueous solution containing 0.1% in weight of carboxymethyl cellulose of average molecular weight of 4500 :.0 and 0.5% in weight of NaCl is prepared. 800 g of charcoal is soaked in 2000 ml of this solution. The duration of soaking is 15 seconds. 110 ml of the solution is absorbed.

After drying the treated- charcoal at 50'C, a charcoal is obtained which has a start of ignition temperature above !5 that of non-treated"charcoal.

By placing a 50 g piece of treated charcoal and a 50 g piece of nontreated charcoal on an electrically heated plate (constant increase of temperature), it will be noted that the treated charcoal ignites +/seconds after the ignition of the non-treated charcoal. Furthermore, the treated charcoal has the advantages of being non-soiling and dust-free. It furthermore also has a lesser friability.

Example 2

Example 1 is repeated but for the fact that the duration of soaking is 1 minute. The charcoal absorbs 120 ml of the composition. The delay in the start of the ignition of the treated charcoal is approximately 20 seconds in relation to the non-treated charcoal. The treated charcoal has the following advantages:

- no release of duff, - non-soiling, 6 great solidity and good shock resistance.

Example 3

Example 1 is repeated but for the fact that 60 mI of the composition is sprayed on to 800 g of charcoal subjected to vibrations. A charcoal which has the following advantages is thus obtained:

- no release of duff, 10 - non-soiling, - great solidity and good shock resistance.

Example 4

Examples 1 to 3 are repeated by means of the following solutidns: solution at 0.1% of carboxymethyl cellulose (MW 4500 and at 1% of NaCl; solution at 0.1% of carboxymethyl cellulose (MW 4500 and at 1% of KCl; solution at 0.1% of carboxymethyl cellulose (MW 4500 and at 1% Of M9C12; solution at 0.1% of carboxymethyl cellulose (MW 4500 and at 0.5% of KCl and 0.5% of NaCl; Example 5

A solution with 1% of rice starch (Romy) and 0.2% of calcium chloride is prepared. This solution is heated to 850C. 800 g of charcoal are added for 30 seconds in 2000 ml of the hot solution. The charcoal absorbs more or less 100 ml of the solution. After drying, the treated charcoal is tested. This test shows a delay in the start of the ignition of the treated charcoal. The charcoal is dust- free and non-soiling.

Example 6

Example 5 is repeated but for the fact that a solution -containing 0.5% of starch and 0.1% of potassium chloride is utilised, that the temperature of the solution is 500C and that the duration of soaking is 11 minute. The treated charcoal is non-soiling and dust-free.

Example 7

ExLmple 6 is repeated, but for the fact that the solution is sprayed on to charcoal subjected to vibrations.

The quantity of the solution sprayed is 60 ml per kg of charcoal.

Example 8

Example 7 is repeated, but for the fact that the solution also contains 0. 5% in weight of NaCl.

Example 9

2-5 Example 8 is repeated, but for the fact that the solution is prepared from a herbal stock (bayleaves, thyme, Provence herbs) in the ratio of 0.5% in weight.

The treatment of the charcoal can be effected by 3C soaking, by spraying, by fogging (formation of a -fog), by atomising, by contact of the charcoal witI, a brush, a spongef or an elastic or supple porous material.

Preferably, the treatment is done by means of a preheated solution (temperature above 40'C) and/or on 8 preheated charcoal. The treatment can be effected in a bath, in a rotation drum, above a vibrating conveyor belt.

After the treatment, the charcoal can possibly be subjected to a drying stage.

9

Claims

Charcoal, the outer surface of which is at least -partially covered by means of at least one layer of a film- --2orming material, characterised in that the layer covering at least partially the outer surface of the charcoal comprises at least, on the one hand, a compound selected -rom the group consisting of cellulose a cellulose -derivative, starch, starch derivative and mixture thereof, and, on the other hand, a compound selected from among the sodium chloride, magnesium chloride, calcium chloride, Dotassium chloride and their mixtures.

2. Charcoal according to claim 1, characterised in that zhe layer at least partially covering the outer surface of zhe charcoal further contains a compound selected from the group consisting of calcium and/or magnesium hydroxide, carbonate or bicarbonate.

3. Charcoal according to claim 1 or 2, said charcoal having pores, characterised in that the layer at least partially covering the outer surface of the charcoal closes at least 25% of the pores of the charcoal.

4- Charcoal according to claim 3, characterised in that at least 50% of the pores of the charcoal are closed.

Charcoal according to any one of the preceding claims, characterised in that its water content is from 3 to 10% in weight.

A. Method for manufacturing charcoal according to any one of the preceding claims, in which the charcoal is treated by means of a solution or suspension containing on the one 1 hand, a compound selected from the group consisting of cellulose 1 a cellulose derivative, starch, starch derivative and mixture thereof, and, on the other hand, a compound selected from among the sodium chloride, magnesium 5 chloride, calcium chloride, potassium chloride and their mIxtures.

1. Method according to claim 6, characterised in that the charcoal is treated by means of an aqueous solution containing on the one hand, a compound selected from the group consisting of cellulose, a cellulose derivative, starch, starch derivative and mixture thereof, and, on the other hand, a compound selected from among the sodium chloride, magnesium chloride, calcium chloride, potassium chloride and their mixtures.

8. Method according to claim 6 or 7, characterised in that the charcoal is soaked in an aqueous solution containing on the one hand, a compound selected from the group consisting of cellulose, a cellulose derivative, starch, starch derivative and mixture, and, on the other hand, a compound selected from among the sodium chloride, magnesium chloride, calcium chloride, potassium chloride and their mixtures.

9. Method according to claim 6 or 7, characterised in that an aqueous solution containing, on the one hand, a compound selected from the group consisting of cellulose, a cellulose derivative, starch, starch derivative and mixture thereof, and on the other hand, a compound selected from among the sodium chloride, magnesium chloride, calcium chloride, potassium chloride and their mixtures is sprayed on to the charcoal.

1 1 10. Method according to any one of the claims 6 to 9, characterised in that the charcoal treated by means of the solution or suspension is subjected to a drying step.

11. Method according to any one of the claims 6 to 10, characterised in that the aqueous solution contains on the one hand, from 0.01 to 1% by weight of a compound selected =om the group consisting of cellulose a cellulose derivative, starch, starch derivative and mixture thereof, and, on the other hand, from 0.1 to 5% by weight of a compound selected from among the sodium chloride, magnesium chloride, calcium chloride, potassium chloride and their mixtures.

12. Method of claim 11, characterised in that the aqueous solution is sprayed on hot charcoal.

13. Installation for the production of charcoal according to any one of the claims 6 to 12, characterised in that it comprises a conveyor belt for moving the charcoal and a device for spraying, fogging or atomising the aqueous solution on to the charcoal.

14. Installation for the production of charcoal according to any one of the claims 6 to 12, characterised in that it comprises a conveyor belt for moving the charcoal into a bath containing the aqueous solution and for removing the treated charcoal from the aforementioned bath.

15. Installation for the production of charcoal according to any one of the claims 6 to 12, characterised in that it comprises a conveyor belt for moving the charcoal to a unit comprising one or several rollers suited for releasing aqueous solution on to the charcoal.

12 16. Installation according to claim 15, characterised in that the roller is a roller comprising an outer porous and elastic layer.

17. Charcoal substantially as herein described with reference to and as exemplified in any of the examples.

18. A method of manufacturing charcoal substantially as herein described with reference to and as exemplified in any of the examples.

19. An installation for the production of charcoal substantially as herein described with reference to and as exemplified in any of the exaitples.