GB2140025A

GB2140025A - Gas producer

Info

Publication number: GB2140025A
Application number: GB08406099A
Authority: GB
Inventors: Willy Evrard
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-03-09
Filing date: 1984-03-08
Publication date: 1984-11-21
Also published as: OA08315A; GB8406099D0; EP0119183A2; ZA841790B; EP0119183A3; BR8401086A

Description

SPECIFICATION Gas producer The present invention relates to improvements in apparatus used for producing a gaseous fuel, the gas produced by these apparatus may be used for different applications, of which one, which is of great interest, is supplying both stationary engines (for example actuating electrogenic assemblies) and mobile engines (for example mounted on vehicles).

The use of gas-producing apparatus for supplying engines has been well known for a long time; various fuels are used: charcoal, peat, lignite, coals (preferably lean coals), coke. The gas obtained is normally the product of incomplete combustion of carbon in a current of air which traverses a thick layer of fuel; this gascalled poor gas-principally contains nitrogen and carbon monoxide, and, additionally, carbon anhydride, hydrogen, methane and possibly a small quantity of ethane.

Conventional gas producers are basically formed by a fuel storage hopper, of which at least the inner part is frustoconical, closed at the base by a grate; a system for introducing the combustion air into the gas producer possibly by induction-and a system for treating the gas obtained complete the installation.

In view of the fact that, for supplying engines, it is necessary to produce a highquality gas and in particular a gas which has been purified as much as possible, it is understood that designers sought to improve the gas-producing and treatment devices so as to increase the cleanness of the product, whilst endeavouring to develop increasingly improved mechanical elements so as to increase the regularity and smooth running of the production process.

The present invention relates to improvements to gas-producing apparatus, its main object being a system for producing gas freed of its impurities by treating the gas produced.

The improved gas producer, to which the present invention relates and which comprises successively a fuel storage-hopper, a combustion furnace supplied with air, a zone for extracting the gas out of the furnace and for evacuating residual solids, means for treating the gas and means for supplying a gas engine, is characterized in that at least one part of the means for treating the gas consists of a circuit penetrating into the combustion furnace.

According to a preferred variant of the invention, the circuit for treating the gas is formed by an evacuation chimney composed of two substantially coaxial ducts, between which there is provided a space for the circulation of the gas, the lower end of the outer duct is open to allow the gas collected in the extraction zone to pass from the base of the furnace, the upper end of the said outer duct is closed, the upper end of the inner duct is located at a certain distance below the closed upper end of the outer duct and is open so as to enable the gas to pass from the outer duct into the inner duct, and the lower part of the said inner duct is connected to means for supplying an engine with gas.

Preferably, the axes of the two substantially coaxial ducts are substantially parallel to the longitudinal axis of the furnace; in an advantageous variant of the invention, the upper end of the outer duct extends into the upper section of the furnace, for example up to the level of the air supply nozzles.

According to an advantageous embodiment of the evacuation chimney constituting a variant of the gas treatment device to which the invention relates, the entry of the gas into the outer duct is ensured both by the lower aperture of the duct and by apertures provided in the lateral wall of the said duct; this embodiment enables the drop in pressure of the system to be decreased whilst ensuring additional contact between the gas which is being evacuated and the incandescent material in the furnace.

According to a further embodiment of the device constituted by the chimney with two ducts, the inner face of the outer duct is provided with baffles, formed, by example, by flat portions, disposed obliquely with respect to the longitudinal axis of the duct; these baffles are heated to a high temperature owing to the proximity of the furnace and also decelerate the gas circulation and thus assist the conversion and cracking reactions, which improve the purification of the gas.

According to yet another particular embodiment of the chimney with two ducts, the upper end of the outer duct is closed by a conical cowl, the inner face of which is provided with baffles, for example formed by flat portions, disposed along the generating lines of the cone; these baffles, which are at a very high temperature, also assist the reactions and, in addition, if they are in a suitable arrangement, force the gas to flow towards the inner duct and to descend therethrough, rather than allowing the gaseous currents to run counter to one another along the wall of the outer duct.In the improved gas producer to which the invention relates, the gas collected in the zone for separating the gaseous products and the residual solids-the gas being at a temperature of 600"C, for example, and comprising a large amount of Cozies forced to rise in the chimney provided between the two coaxial ducts and is reheated to approximately 1 000 C at the (closed) top of the chimney; owing to the proximity of the furnace, the CO2 in particular is converted into CO, whilst various hydrocarbons and undesirable elements are cracked; the gas improved in this way is then sucked into the inner duct where it descends and reaches the means for transferring it to the engine; of course, on the way, the gas may also traverse other means for treatment and purification by a wet or dry process.

In a further embodiment of the invention the high temperature gas leaving the base of the inner duct is made to circulate about the lower part of the furnace; the gas thus assists in maintaining this part of the device at a satisfactory temperature for encouraging the Durifying reactions.

After circulating in a casing surrounding this zone, the gas is finally sucked into pipes which extract it from the producer.

The improved gas producer described above enables a gas to be produced which is purified to an acceptable degree, is free from water vapour, residual carbon-containing solids, etc., under particularly simple and eco gnomic conditions; it can be used to produce gas from the fuels mentioned above and also using various substances, including natural fibrous materials (wood, straw, plants), possibly after compaction.

The invention will be further described by way of example, with reference to the accompanying single figure of drawings which shows in cross-section gas treatment means of a gas producer according to the invention.

The single figure of drawings shows a vertical section of the zone of a gas producer to which the invention particularly relates. A combustion zone (1) has nozzles (2) and (3) for the supply of air; below this zone is a zone which has a section which firstly decreases (4) in cross-section and is then flared (5) and in which gases are extracted from the furnace and separated from residual solids which are deposited on a grate (6).

The gases penetrate, via annular opening (7), into a space formed between two coaxial ducts, one (8! of which is external and the other (9) internal; at the top of the chimney formed in this way the rising path of the gas is interrupted and the gas descends again through the interior (10) of the internal duct and reaches outlet pipes (11) of the furnace interior. The gas is then made to circulate in a closed space (13) surrounding the lower part of the furnace before reaching evacuation pipes (14) connected for example to an engine. The arrows in the drawing show diagrammatically the path followed by the gas traversing the device according to the invention. Means (not shown) for the evacuation or removal of the residual solids are located in the space (12) above the grate.

In a particularly advantageous embodiment of the producer to which the present invention relates the part of the furnace located below the gas formation zone is leaktight; this arrangement is particularly appropriate at the base of the furnace, for example in the vicinitv of and at the level of the solace (12) for the deposition and evacuation of the residual solids. This air tightness, which of course need not necessarily be perfect, prevents gas emerging at this level and therefore forces the gas to follow the circuit which brings it into the high temperature zone of the invention.

In addition, this air tightness prevents the gas from being charged with impurities again a d therefore preserves the cleanness which the system as a whole aims to ensure.

Claims

1. A gas producer comprising in series a storage hopper for fuel, a combustion furnace supplied with air, a zone for extracting gas frorn the furnace and for evacuating residual solids, means for treating the gas and means for supplying the gas to power a gas engine, wherein the means for treating the gas includes means for raising the temperature of the gas.

2. A gas producer as claimed in claim 1, wherein the means for raising the temperature of the gas comprises means for circulating the gas in a high temperature zone.

3. A gas producer as claimed in claim 1 or 2, wherein the gas temperature is raised by circulating the gas in the vicinity of the combustion furnace.

4. A gas producer as claimed in claim 3, wherein the gas is circulated within the combustion furnace.

5. A gas producer as claimed in a y one of claims 1 to 4, wherein the mea s for raising the temperature of the gas comprises a evacuation chim ey consisting of two substantially coaxial ducts between which there is a space for circulation of the gas, a lower end of the outer duct being open to allow the passage therein of gas collected in the extraction zone at the base of the furnace, the upper end of the outer duct being closed, a upper end of the inner duct being located at a certain distance below the closed upper end of the outer duct and being open to allow gas to pass from the outer duct into the inner duct, and the lower part of the said inner duct being connected to the means for supplying a engine with the gas.

6; A gas producer as claimed in claim 5, wherein the upper end of the outer duct extends into the upper part of the furnace.

7. A gas producer as claimed in claim 6, wherein the upper end of the outer duct extends into the upper part of the furnace as far as the level of the air supply nozzles.

8. A gas producer as claimed in claim 5, 6 or 7, wherein the entry of the gas into the outer duct is ensured both by the opening at the lower end of said duct and by openings provided in the side wall of said duct.

9. A gas producer as claimed in any one of claims 5 to 8, wherein baffles are provided on the inner wall of the outer duct.

10. A gas producer as claimed in claim 9, wherein the baffles are constituted by flat parts, disposed obliquely with respect to the longitudinal axis of the duct.

11. A gas producer as claimed in any one of claims 5 to 10, wherein the upper end of the outer duct is closed by a conical cowl having baffles on the inner face thereof.

1 2. A gas producer as claimed in claim 11, wherein the baffles on the cowl are constituted by flat parts, arranged along generating lines of the cone.

1 3. A gas producer as claimed in any one of claims 1 to 12, wherein the high temperature gas is circulated about the lower part of the furnace, and the gas is finally sucked into pipes which extract it from the producer.

14. A gas producer as claimed in any one of claims 1 to 13, wherein the region of the producer located below the gas for ing level is leaktight.

1 5. A gas producer substantially as hereinbefore described with reference to the accompanying drawings.