WO1981001010A1

WO1981001010A1 - Method and apparatus for producing gas

Info

Publication number: WO1981001010A1
Application number: PCT/DK1980/000060
Authority: WO
Inventors: B Bruun
Original assignee: B & W Alpha Diesel; B Bruun
Priority date: 1979-10-02
Filing date: 1980-10-02
Publication date: 1981-04-16
Also published as: JPS56501321A; DK412379A; EP0040202A1

Abstract

A reactor (2) for producing gases by reacting carbon containing materials (1) is provided with an extruder (3) which compresses and supplies the material. The extruder can consist of a tube (8) with a hollow rotatable shaft (10, 11) which is provided with a worm (9), which worm has a decreasing pitch and a decreasing cross-sectional area towards the outlet tube. Steam (4), air (5) and/or heat (6, 7) can be introduced into the reactor (2), if desired through the shaft (10, 11). In the extruder specific gravity and moisture content can be regulated whereby an entirely homogeneous material with respect to specific gravity and moisture content is introduced into the reactor. Thus the optimum thermal process is ensured and consequently the best utilization of the caloric value of the raw material. Moreover, the reactor (2) and the extruder (3) can be built together whereby a simple and compact unit is obtained which can work in small units and under all circumstances not requiring any specific position to be able to work.

Description

METHOD AND APPARATUS FOR PRODUCING GAS

The invention relates to a method for producing gases by reacting carbon containing including cellulose containing materials in a reactor, and an apparatus for carrying out the method.

It is known to produce gas with a high calorific value and with a homogeneous quality and composition by pyrolyzing carbon containing materials such as wood, peat and stems of annual plants. The variable moisture content and the useful solid matter content of such materials pose a problem, however, as the thermal treatment of the material before the pyrolysis influences the result of the gas generation.

In order to increase the efficiency and at the same time ensure a homogeneous gas quality it is therefore necessary to treat the material in a separate vaporization and drying plant and perhaps to divide the material into fine parts before it can finally be introduced into a reactor.

If this pretreatment of the material has to take place con¬ tinuously, the material has to be transported from plant to plant in pipes before it can finally be introduced into the reactor. In practice this means that plants have to be comprehensive and complicated to carry out the pretreatment just as means of conveyance for conveying the material are required.

It is the object of the invention to remedy these deficien¬ cies in the known methods, and this is achieved when the material is introduced into the reactor by means of at least one extruder wherein the consistency including specific gravity and moisture content can be adjusted. It is thus possible in a very simple way to procure the optimum work- ing conditions for the reaction as the necessary adjustmen of the material can be effected in the extruder. The mater can be introduced into the extruder, the specific gravity of the material being a result of the pressure to which the material is exposed in connection with the pressing into the reactor. This pressure can if necessary be adjust by making the cross-sectional area of the extruder variabl When making the area smaller, pressure increases. The mois ture content can in a known manner be adjusted by adding steam or water or the material can be dried by means of he Using suitable control equipment it is thus possible to ensure that the introduced material is always homogeneous whereby the reaction becomes uniformly optimal.

By optionally admitting steam, air and heat to the reactor as disclosed in claim 2, the pyrolysis can take place in such a way that the gas and the waste products are the bes possible for the operation.

By regulating the air flow through the extruder, as disclo in claim 3_S the reactor can work either as a pressure or a suction reactor as undesirable air or gas cannot get in out through the material in the extruder when working.

By using the extruder disclosed in claim a simple and ho geneous compaction of the material is achieved.

By using the extruder disclosed in claim 5 consisting of a worm on a conical shaft a simple conveying and compaction of the material is obtained. The worm can moreover be_. pro¬ vided with cutting edges for a possible division into fine parts of the material.

Finally it is suitable to make the shaft hollow, as disclo in claim 6, admitting matters like air, water and steam

_0:V.PI into the reactor through the shaft.

The invention will be further described in the following with reference to the drawing showing a section of a plant for carrying out the method.

The apparatus shown on the drawing is one example of an embodiment. It comprises a reactor 2 consisting of a closed chamber which on the inside can be lined with ceramic materials. Moreover, means for producing a swirl chamber for promoting the thermal process can be provided inside. In contact with the reactor wall there are provided one or more ducts or heating coils 6 or electrical heating elements.

At the underside of the reactor there is mounted an extruder

3 comprising a tube 8 wherein a pivotally mounted shaft 10, 11 is provided, and to which shaft a worm -is. fasten¬ ed.

The worm has a steep pitch at the bottem where.the material is supplied. If desired, cutting means for dividing the material into fine parts can be secured to the worm. The shaft is conical with an increasing diameter upwards to the end of the worm. The remaining part of the shaft 11 is cylindrical and it can go somewhat into the chamber as shown. If desired, the worm can have a decreasing diameter so that the cubic content of the extruder becomes smaller and thus results is an increased compression.

The shaft 10, 11 is hollow so that air 5 and water or steam can be supplied into the chamber. Next to the extruder is mounted a hot bulb 7 and/or an extra nozzle for supplying _air, water or steam.

When the extruder shaft 10, 11 is turned by a not shown device, the material 1 is carried into the worm 9 where it is conveyed upwards, and because of the decreasing pitch and the diameter increase of the shaft the material is co pressed so that it is packed between the shaft 11 and the tube wall 8. When it reaches the mouth of the extruder at the reactor, it is completely uniformly compressed and in such a state which will depend on the friction and the material. Pressure is namely being exerted until the mate rial is pressed out of the extruder which thus becomes self-regulating with respect to the compression, and a quite homogeneous material is constantly being supplied to the reactor. As mentioned the cross-sectional area of the tube 8 can be made adjustable be means of not shown means for increasing or decreasing the cross-sectional are

In the extruder temperature as well as moisture content o the material can be controlled by not shown measuring, dosing and control means. The result is that the desired uniform admission of material is ensured which is of the greatest importance to the thermal process in the reactor.

At the top of the reactor is mounted a gas outlet pipe 12 which is taken to a dust filter 13 that can contain a suit able filtering material 14. Here fly ash and possible con¬ densate 15 settle at the bottom of the filter where it can be drained off through an outlet with a valve or a gate 16. In this filter 13 can moreover be mounted a not shown heat exchanger whereby the heat from the gas can be used for instance for producing steam which can either be supplied to the reactor through the shaft, the bottom nozzle or can be admitted into the duct 6 in the reactor wall or be sup¬ plied to the extruder 3.

_At a suitable place on the reactor there are moreover not shown means for removing combustion products such as ashes or cinders. The dust filter is provided with an outlet pipe 17 with a suction pump 18 for exhausting the gas from the plant. In¬ stead of a suction pump the process can also take place by positive pressure by generally known means. The advantage of using a suction pump is that combustion products can be removed during the operation.

The method will now be described in the following. As a raw material cut straw can for instance be used. All carbon con¬ taining including cellulose containing materials can be used, however, if they are just present in a state which can be utilized in the extruder.

In the extruder a division into fine parts and a regulation of the moisture of the straw can take place, just as the straw is exposed to a compression in the extruder. It is then pressed into the extruder where it is heated to at least 600 C by the admitted superheated steam >_ or in another way f.inst. by means of the hot bulb 7 or the heating coil 6. By this action of heat the straw is first converted into carbon when the carbon is converted into gas by pyrolysis by means of the admitted air 5 and/or water , 7. This admission of air and/or water, steam is automatically controlled by generally known control means.

The process is continuous and self-regulating and utilizes the caloric value of the raw material to a previously un¬ known high degree. The gas produced by the degasing of f. inst. straw has the following composition:

Hydrogen H₂ 33,92

Oxygen °2 2,52

Nitrogen ^N2 8,02

C Caarrbboonn mmoonnooxxiiddee C COO 26,92

Methane CH^ 13,52

Carbon dioxide CO., 15,02

Claims

P A T E N T C L A I M S

1 1. Method for producing gases by reacting carbon contain¬ ing including cellulose containing materials in a reactor, c h a r a c t e r i z e d i n that materials (1) are introduced into the reactor (2) by means of at least one

5 extruder (3) wherein the consistency including specific gravity and moisture content can be adjusted.

2. Method according to claim 1, c h a r a c t e r i z e d i n that steam (4), air (5) and heat (6, 7) can be option- 0 ally introduced into the reactor (2).

3. Method according to claim 1 and 2, c h a r a c t e r ¬ i z e d i n that the air flow through the extruder (3) ca be adjusted when working. 5

4. Apparatus for carrying out the method according to clai 1-3, c h a r a c t e r i z e d i n that the extruder (3) comprises a tube (8) leading to the reactor (2) in which tube a conveyor (9, 10) supplies and compresses the material 0 (1).

5. Apparatus according to claim 4, c h a r a c t e r i z e i n that the conveyor consists of a worm (9) on a rotatable shaft (10), the cross-sectional area of which is reduced in 5 the travelling direction of the material towards the end of the worm (9).

6. Apparatus according to claim 5, c h a r a c t e r i z e i n that the shaft (10, 11) is provided with one or more 0 throμgh-going ducts.