FR2497819A1 - Gas generator, which can burn damp wood or maize cobs - where generator contains cracking and redn. zones producing gas contg. large amts. of hydrogen and carbon mon:oxide - Google Patents

Abstract

The generator consists of a vertical cylinder with a top inlet for vegetable matter. Near the base of the cylinder is a hearth formed by an upper oxidn. cone(a), and a lower redn. cone(b). A cracking zone(a1) is formed at the base of cone(a). Zone(b) is heated to over 700 deg.C., pref. by using an outer skirt to feed air into the top of cone(a). A distn. tray is used to remove excess water obtd. from damp fuels. The oxidn., redn. and cracking zones are pref. kept at ca. 1000 deg.C.; and preheated air is pref. fed through tuyeres located at the middle of the height of cone(a). The generator provides a gas mixt. rich in H2 and CO, and used in petrol engines, or mixed with diesel oil and used in diesel engines. In regions where wood is scarce, maize cobs can be used as the fuel.

Description

 The present invention relates to a gasifier allowing the manufacture of a gas usable in the internal combustion engine or the diesel engine.

There are already known gasifiers producing a mixture of carbon dioxide C02 and carbon monoxide CO, with nitrogen
N2, from coal. They were widely used during the Second World War. However, we sought to develop other energy sources, because even coal was becoming relatively scarce in Western countries. to use wood as fuel. Conventional wood gasifiers generally consist of a hopper which contains the wood, a hearth, a combustion air supply, a gas outlet pipe, dedusters and coolers of the gases which are then brought into the engine, via a compressor. The production of the gases takes place in several stages. The carbon is transformed into carbon dioxide in an exothermic reaction

Then the high temperature carbon reduces the carbon dioxide according to another exothermic reaction:

The lean gas is obtained, which also contains a high proportion of nitrogen from the air.

With water vapor, the carbon acts on it according to strongly endothermic reactions:

These reactions cool the mass and, below 70sec, they practically no longer take place, which is why all known wood gasifiers are designed to be used with dry wood. This condition is particularly difficult to obtain and the wood always contains a significant amount of water, even after a long drying time and passage to the oven.

These latter operations are costly and therefore increase the cost price of the fuel.

 The combustion of wood also leads to the formation of tars and pyroligneous acid. To reduce these bodies, several solutions have been envisaged. In particular, a "diabolo" shape has been given to the hearth, which creates a shrinking by which all gases are forced to pass and the tars are then cracked. In practice, in these known gasifiers, there remains a significant proportion of impurities and there is therefore recorded rapid wear of the engine. gas, we can only use wood and not plants, because then the production of pyroligneous diacid, body difficult if not impossible to eliminate, is top important.

 But wood still remains a source of energy which, although cheap, and important in countries with large forests such as France, Norway or Sweden, tends to become scarce in the Mediterranean countries. However, in the regions where we grow corn in large quantities, farmers.

after drying the ears, harvest the grains. They then have the central part of the ear, called the cob. The rays are unused and burned. It would therefore be particularly advantageous to have gas generators burning plant waste such as cobs.

In addition, in the gasifiers @ ourants, the fuel tends to settle and form a vault above the hearth, which leads to poor combustion. The suspensions of vehicles fitted with garogens are good and the r @ utes being curved , @@ hots do not occur which could bring down the pieces of wood. It is therefore necessary to open the door through which the fuel is introduced and to push the wood using an iron bar. This manipulation is very dangerous for the worker who performs it because the risks of explosion are significant.
The invention aims to combine all the drawbacks listed above.

 An object of the present invention is therefore to provide a properly functioning gasifier to wood, possibly wet, or with corn cobs.

 A second object of the invention is to increase the yield of such a gasifier, by increasing the heat power of the gases and their power of explosion.

 Another object of the invention is to have control over the hearth, without having to climb on the device to access the fuel supply opening.

 To achieve these goals, the invention is such that a gasifier comprising a hearth consisting of a lower cone delimiting a reduction zone, an inverted upper cone delimiting an oxidation zone and a cracking zone, is provided furthermore a means of heating, to more than 700 ° C., the reduction zone, preferably at 1000 ° C., and a means of removing volatile acids and tars, as well as excess water , said means being an integral part of said gasifier.

 The heating means is for example an external jacket surrounding the hearth. Thus the hearth is maintained at a temperature of approximately 1000 OC and the hydrogen production reactions which are very endothermic, take place. fuel is transformed into hydrogen. The gas obtained is much richer in combustible products (C0 and H2) and its calorific and explosive power is therefore much higher than that of gas obtained from common gasifiers. contained in the fuel is transformed into water vapor which is consumed and it is thus possible to use wet materials. It is probable that the combustion air is heated to around 200 OC, when the gasifier is in operation, because the hearth is maintained at a temperature in the region of 1000 OC. It is possible to maintain this temperature because the combustion air is blown in through nozzles situated approximately halfway up the upper cane delimiting the oxy zone The nozzles are preferably six in number.

 Excess water is removed by means of a distillation tray located at the top of the gasifier. This tray also has the function of removing pyroligneous acids and volatile tars. reaction with red fuels in the fireplace therefore does not interfere with the reactions.

The fuel is dry wood or not or else cobs of corn but mixed or not with the wood. Thus, thanks to the gas generator according to the present invention, the agricultural waste is recovered
There is also an opening located just above the hearth.Thanks to this opening, the fuel can be dropped into the hearth.Moreover, this opening, where it is located, does not cause risk of explosion during this last manipulation.

 This description, with reference to the single figure annexed by way of nonlimiting example, will make it possible to better understand how the invention can be put into practice.

 The gasifier according to the present invention, represented in section in the figure, consists of a metallic cylindrical enclosure 1, of a door 2 by which the wood or mas stems are introduced, of a hearth consisting of a cone upper 5 doxydation.Un lower cone 3 defines a reduction zone 12 and is provided with a skirt 4 inclined inward.

The cracking takes place in zone 16 located at the bottom 11 of zone 13 of combustion or oxidation.

 The door 6 'closes the opening 6 which allows the control of the hearth and the ignition. Your door 7 is used to remove the ashes which are deposited on the grid 8 which can be shaken using the pull tab 9 or remotely using an electric control.

 The gasifier includes a distillation plate 17 located at the upper end of the enclosure 1. In addition, the nozzles 10, generally six in number, allow air to be blown into the primary combustion zone 13.

 The device comprises a liner 17 and a pipe 18 which can separate from the nozzles of the Pide of the seal 19.

Excess water, acids and tars are collected via line 20 and discharged through valve 21. Intermediate gutters 25 can be provided which collect heavier tars.

 The supply circuit 21 of the gas mixture to the engine 22 comprises a purifier 30, a non-return filter 23 and a dust-collector 24.

The operation of the gasifier according to the invention is as follows t
We introduce through the door 2 of the damp roof or not, cut into pieces of adequate size by a crusher. This kind of high-performance crusher currently exists on the market.

The wood comes from tree heads or felled branches.

regularly for the annual maintenance of the forests. We can also introduce cobs of corn but alone or in mixture with the pieces of wood. The cobs come from the ears of corn dried on "crib" by the action of the sun and the wind. eight or ten months of drying, the grain is separated from the cob, which still contains a significant part of water.

In addition, it has a high calorific value. This fuel is equivalent to 300 l of diesel oil per tonne. 0r, a minimum of two tonnes of March roundups per hectare is obtained.

Then ignite the gasifier with a torch soaked in sparkling alcohol or with metaldehyde which is ignited
andwhich is introduced through the door 6 or through one of the nozzles, after having rotated the pipe 18.

Then close the ignition door ~~~~~~~.
rate in the combustion zone 13 will start to burn under the action of the air which penetrates, according to arrow 26, and via the nozzles 10, in the primary combustion zone 13.The temperature of the hearth rises, but the composition of the synthesized gas is not yet good enough to allow connection to the engine; it is therefore interrupted until the temperature of the primary zone 13 is approximately 1000 C. The gases which pass through the reduction zone 12 according to arrow 27, are reduced. The temperature of the reduction zone is greater than 700 ° C., due to the heating of the air ring comprised between the jacket 17 and the enclosure 1 properly This gas ring also cools the gases formed which rise in the direction of the arrow 28. Another advantage of the lining is therefore to cool the enclosure 1 of the gasifier and therefore to avoid risks of burns by touching the body of the gas generator. water is good and we get hydrogen in the final mixture. So we see that in zone 13,
carbon dioxide is produced which is non-combustible and
that in zone 12 there is a reduction of carbon by water
with formation of carbon monoxide and hydrogen gas
high calorific power and great power of explosion.

In addition, in zone 16 there is a cracking of the goù
heaviest drons and organic compounds from
most volatile tars as well
that the pyroligneux acid go up according to the arrows 28 and 29,
to reach the goutike where they condense.

 The water contained in the fuel evaporates due to the heat of the hearth and a portion condenses on the trays 25, then is eliminated through line 20 and the water, acids and volatile tars are discharged into the tap help 21.

 When the gaseous mixture is of an adequate composition, it is sent to the engine by starting it, there is then a vacuum of the order of 0.1 to 0t4 Bar inside the gasifier. therefore avoids any risk of explosion.

The opening 6 closed by the door 6 allows control over the fireplace without having to climb to the top of the appliance or to open the fuel loading door. Through this opening you can pass an iron rod or other to push the wood or the roundup and destroy the vault which would be likely to form. All accident is thus avoided
The gasifier according to the invention can be used for a conventional combustion engine.

 However, many engines of agricultural vehicles or machines using large power engines are equipped with diesel engines. 0n can provide them with a gasifier according to the present invention and provide them with a gasSoil / gasifier gas mixture, subject to the adaptation of '' a manual adjustment of the injection on each type of pump.

Claims (8)

CLAIMS. l. Gas generator comprising in particular a hearth consisting of a lower cone (3) delimiting a reduction zone (l2) and an inverted upper cone (5) delimiting an oxidation zone (13) and a cracking zone (l6 ), characterized in that it is provided with a means of heating to more than 700 ° C. from the reduction zone, and with a means of removing excess water. 2.Gas generator according to claim l, characterized in that the means for heating the reduction zone is a jacket disposed around the hearth. At the level of the reduction zone (l2). 3.Gasogen according to claim 1 or 2, characterized in that the reduction zone (12) is heated to approximately 1000 OC. 4.Cazogen according to any one of the preceding claims, characterized in that the means for removing excess water is a distillation plate (l /) located at the top of the gasifier. 5.Gasogen according to any one of the preceding claims, characterized in that the temperature of the oxidation zone and of the cracking zone is maintained at approximately 1000 OC. 6.Gasogen according to any one of the preceding claims, characterized in that it comprises insufflation nozzles (l0) of hot combustion air, preferably six in number, located approximately halfway up the cone d 'oxidation. 7.Cazogen according to any one of the preceding claims, characterized in that the fuel is wet wood. 8.Cazogen according to any one of claims 1 to 6, characterized in that one uses as fuel March stalks.  gasifier according to any one of claims 1 to 6, characterized in that the fuel is a wet mixture of wood and cob.  10.Engine equipped with a gasifier according to any one of the preceding claims, characterized in that said gasifier provides it with a gaseous mixture with a high proportion of hydrogen and carbon monoxide.