Gasification and/or Pyrolysis

Abstract

The present invention provides a method and apparatus for gasifying/pyrolysing material containing organic matter including introducing the material into a treatment chamber (2) and heating the material by passing a flow of hot gas (30) containing less than 8% oxygen through the chamber (2) so as to cause the material therein to gasify or pyrolyse. In a first mode of operation the gas (30) is passed through the chamber (2) at a first velocity. The apparatus comprises a means (20, 21) for temporarily increasing the velocity of the hot gas (30) such that in a second mode of operation the velocity of the gas (30) exiting the means (20, 21) is temporarily increased.

Description

The present invention relates to gasification and pyrolysis of matter, such as waste matter, containing an organic content, in particular the invention relates to increasing the efficiency of methods and apparatus for performing gasification and pyrolysis.

The pyrolysis and gasification of organic material in both static and rotating treatment chambers is known in the art. These are generally classified into batch processing equipment, where the material is treated one batch at a time, and constant process equipment where there is a constant through flow of material. In both heating of the material is generally done by passing hot gas through the treatment chambers. To keep constant process parameters the gas flow is usually regulated to keep it at a relatively constant flow, and often the flow rate of the hot gasses may be determined by external factors, for example the process gas produced from the pyrolysis/gasification process will often need treatment to remove volatile organic compounds therefrom and the gas flow rate will be effected by parameters of the process gas treatment.

Examples of known type batch pyrolysis apparatus is described in WO/2004 059229 and WO/2006 100512 in the name of Al Chalabi et al, in which a de-coating method is described for gasifying/pyrolysing organic coatings on metal materials.

The agitation of the treated material greatly improves the gasification/pyrolysis process as it exposes greater surface areas to the hot gasses. This is traditionally achieved by physical agitation, often by rotating the oven to cause the material to move therein. Although this is effective, physical agitation often requires altering the movement of the oven (when moving ovens are used) or introducing some form of agitation means in an already rotating oven which introduces technical challenges doe to the changing forces on the agitation means resulting from the movement of the oven. Furthermore during processing it is not uncommon for materials to soften and start to clump together and move as one mass as the oven rotates. This not only reduces the effectiveness of known agitation means but can clog up mechanical type agitators if provided within the oven. In another example it may be advantageous to replace mechanical rotation of the oven with a more static form of material agitation so as to reduce moving parts.

It is the purpose of the present invention to provide an improved agitation of material during a gasification process.

According to a first aspect of the invention there is provided a method of gasifying and/or pyrolysing material containing organic matter, the method comprising: introducing said material into a treatment chamber; heating said material by passing a flow of hot gas containing less than 8% oxygen by volume through said chamber so as to cause the material therein to pyrolyse or gasify; in a first mode of operation the gas is passed through the chamber at a first velocity; providing a means for temporarily increasing the velocity of the hot gas; and in a second mode of operation, temporarily increasing the velocity of the gas.

Typically approximately 5% oxygen by volume is used for a gasification process and less than 1% oxygen by volume is used for a pyrolysis process. In the first instance the hot gas exiting the processing chamber has in the region of 1% oxygen content and in the second instance the hot gas exiting the processing chamber has substantially 0% oxygen content. It will however be appreciated that the volumes of oxygen entering and exiting the chamber can be varied to control the processing of the material therein.

Providing a means for temporarily increasing the velocity of the gas preferably comprises: providing a reservoir vessel for the hot gas upstream of the treatment chamber; filling the reservoir vessel with hot gas at a first rate; and ejecting the hot gas from the reservoir at a second rate greater than the first rate.

The method according may further comprise: providing a reservoir vessel having a piston therein and an actuator for driving said piston, and wherein ejecting the hot gas comprises activating said actuator so as to move the piston to force hot gas from the reservoir vessel.

The vessel may be provided with an inlet and an outlet on either side of said piston, and the method may comprise opening one inlet on one side of the piston and opening one outlet on the opposite side of said piston; and in the first mode of operation moving said piston so that the instantaneous volumetric flow rate of the gas passing through the inlet is substantially equal to the instantaneous volumetric flow rate passing through the outlet. Preferably, in the second mode of operation the piston is moved at a speed greater than in the first mode of operation so as to force the air from the vessel through the outlet.

The piston may be moved in a series of steps so as to provide a pulsed flow of hot gas through the outlet.

Where the vessel has an inlet and an outlet on either side of said piston, the method may further comprise, in a further mode of operation: opening the inlet and the outlet on the same side of the piston so as to provide a through flow through the vessel on one side of the piston.

According to a second aspect of the invention there is provided an apparatus for gasifying and/or pyrolysing material containing organic matter, the apparatus comprising: a processing chamber for receiving material to be gassified; a processing chamber inlet for receiving hot gas; a processing chamber outlet for exhausting hot gas; and means for, in use, temporarily increasing the velocity of hot gas flowing into the inlet from a first velocity to a second higher velocity. The apparatus may be used for carrying out the method of the first aspect of the invention.

The means for temporarily increasing the velocity of hot gas may comprise: a reservoir chamber forming a cylinder and having a piston therein dividing the reservoir chamber into a first section and a second section; at least one reservoir inlet and at least one reservoir outlet; a drive means connected to said piston configured to drive said piston in said chamber; and a control means configured to control said drive means to selectively drive said piston in said reservoir so as to expel hot gas from said reservoir in an accelerated manner.

The apparatus can further comprise a first inlet and a first outlet in said reservoir chamber on one side of said piston and a second inlet and a second outlet in said reservoir chamber on the other side of said piston; and wherein the control means is configured to, in a first drive direction close the first outlet and the second inlet and operate the drive means so as to move the piston from the first inlet towards the second outlet so that hot gas flows into the first section and out of the second section. Further, the control means may be configured to, in a second drive direction open the first outlet and the second inlet, and close the first inlet and second outlet, and operate the drive means so as to move the piston from the second inlet towards the first outlet so that hot gas flows into the second section and out of the first section.

In one arrangement, in a first mode of operation the controller is configured to operate the drive means to move the piston at a speed such that the instantaneous flow rate of the gas expelled from the reservoir is substantially equal to the instantaneous flow rate of the gas entering the reservoir; and preferably, in a second mode of operation the controller is configured to operate the drive means to move the piston at a speed such that the instantaneous flow rate of the gas expelled from the reservoir is greater than the instantaneous flow rate of the gas entering the reservoir.

In the second mode of operation the controller may be configured to operate the drive means in a plurality of discreet steps such that the gas expelled from the reservoir is expelled in a plurality of accelerated bursts of gas.

Embodiments of the invention will now be described, by way of example, in relation to the drawings in which:

FIG. 1 is a side view of a gasification/pyrolysis apparatus for use with the invention;

FIG. 2 is a partially cut away isometric view of the apparatus of FIG. 1;

FIG. 3 is an isometric view of an apparatus in accordance with the invention; and

FIG. 4 is a plan view of an apparatus in accordance with the invention.

As stated above the proposed invention is for use with gasification/pyrolysis chambers which may be of a static type or of the rotating type as described in prior art documents. The example described in detail herein is in relation too rotating type chambers, although It will be apparent to the skilled person how this could be modified for use with static type ovens, the scope of the invention not being limited to either type.

FIGS. 1 and 2 show a gasification/pyrolysis machine which has an outside casing 2, and which mounts a processing chamber 1 within to contain and process material. The material may be waste material containing organic content, for example municipal or industrial waste, or may alternatively be any material containing organic matter, The waste is loaded into a detachable bin 4 which is then attached to the apparatus.

Hot inlet gas enters the processing chamber 1 via the inlet duct 5. The outlet gas which will contain process gasses released from the gasification/pyrolysis of the waste exits the processing chamber 1 via the outlet duct 6.

FIG. 2 shows a view of the chamber with the end panels removed to show the processing chamber 1 within. The hot gas enters through the duct 5 and enters the chamber 1 where it fills the chamber cavity which acts as an inlet plenum and thereafter flows through the holes in the inlet panel 7, which forms one of the sides of the processing container 1, and into the process area containing the waste material.

The duct 6 is connected to a sealed compartment which forms an exit plenum which is connected to the processing chamber 1 via holes in an exit panel 8 which forms one of the sides of the processing container and allows process gas to flow from the processing area.

A rotating joint 9 allows the static hot gas inlet duct 24 and static outlet duct 10 to be connected to the moving hot gas inlet duct 5 and moving outlet duct 6 so as to allow the rotation of the chamber 2 in the direction of the arrow 28 approximately 200 degrees and back again in the direction of arrow 27, whilst supported by pivotal mounts on frames 3.

Referring to FIGS. 3 and 4, these show perspective and plan views of the invention when used with the apparatus shown in FIGS. 1 ad 2.

The apparatus has a reservoir comprising compression chamber 20 which houses a piston 21. The piston 21 is moved backwards and forwards in the direction of arrows 25 and 26 as depicted in FIG. 4 under the power of an actuator 23, which may be of a hydraulic, electric or pneumatic type or indeed any suitable drive means.

The purpose of the chamber 20 and piston 21 is to provide a means of increasing the hot gas flow 30 velocity through the holes in the inlet panel 7 of the processing chamber 1 to enhance the gasification process. By increasing the velocity of the gas it can penetrate further into material within the chamber and expose greater surface areas of the material to the hot gas flow. Furthermore the accelerated gas flow agitates the material in the processing chamber as it flows thereinto. This has particular effect when the oven is rotated fully in the direction of arrow 28 as, as will be appreciated the material will fall towards the inlets of the oven as the oven rotates. When in proximity to the inlets the increase in the velocity of the gas entering via the inlets is particularly beneficial in increasing agitation and gas penetration into the material to assist processing.

Beneficially, with the preset arrangement the total volume of hot gas flow 30 through the duct 5 remains constant over time but the velocity can be increased in regular pulses or short bursts as required. This enables the benefits of increase velocity pulses to be combined with overall process benefits of running the whole apparatus at a substantially constant gas flow.

Again with reference to FIGS. 3 and 4, the apparatus is mounted in an inlet duct 11 which splits into two ducts 16 and 17. Duct 16 enters at one end of the compression chamber 20 and duct 17 enters at the opposite end of the chamber 20. A first inlet damper valve 12 is positioned in the duct 16 and a second inlet damper valve 13 is positioned in the duct 17.

Chamber exit duct 18 leads from the compression chamber 20 on one side of the piston and allows the hot gas 30 to exit at one end thereof and chamber exit duct 19 is mounted at the opposite end of the compression chamber on the other side of the piston and allows the hot gas 30 to exit at the opposite end of the chamber 20.

A first outlet damper valve 14 is positioned in the duct 18 and a second outlet damper valve 15 is positioned in the duct 19. Ducts 18 and 19 join together to form inlet duct 24.

The flow rate of the hot inlet gas 30 can be adjusted by controlling the operation of the piston 21 in the chamber 20. A controller (not shown) controls the operation of the actuator 23 and the inlet and outlet valves.

In one mode of operation the piston 21, moves inside the compression chamber under automated control in direct proportion to the flow of hot inlet gas 30 through valves 12 and 13 on entry to the chamber 20.

A typical operational sequence would be: close valves 13 and 14 and open valves 12 and 15. As the hot gas 30 flows through duct 16 and fills the volume of space behind the piston 21, in the chamber 20, the actuator 23 moves the piston 21 in the direction of arrow 25 as shown in FIG. 4. The piston 21 moves at a minimum proportional rate, and higher in relation to the flow of gas 30 so that the volume increases behind the piston in direct relation to the volume of gas entering the chamber such that the system pressure of the gas is unaffected and no pressure build up is created on the inlet side of the chamber. In this way the use of the apparatus of the invention does not have any knock on effect on the upstream gas pressure or flow that is being provided to the chamber 20. This enables upstream gas processes to be carried out without needing to compensate or take into account any pressure or flow effects of the downstream equipment.

The flow and pressure of the hot gas 30 into the compression chamber 20 will be the same as the system pressure or the same as if the chamber were not present, because the hot gas 30 just fills the space behind the piston 21, which is controlled to increase the volume as the hot gas 30 flows into the chamber 20.

When required to accelerate the outflow of gas from the chamber 20 the piston 21 can be controlled to move more rapidly as required to give powerful bursts of gas velocity without the need to synchronise with the flow rate of inlet gas 30 into the chamber 20. If space is created behind the piston 21, quicker than the gas flow into the compression chamber 20 then it does not matter, gas will enter to fill this space to balance the gas being expelled from the cylinder.

The more rapid movement of the piston 21 in the direction of arrow 25 means that the velocity of the hot gas 30 is higher out of the chamber 20, through duct 19 and valve 15, into the duct 24, and finally through the duct 5 and into the processing chamber 1 via the holes in the panel 7 as shown in FIG. 2.

When the piston 21 reaches the end of the stroke in the travel direction of arrow 25 then valves 13 and 14 are opened and valves 12 and 15 are closed. As the hot gas 30 flows through the valve 13 and duct 17 and fills the volume of space behind the piston 21, in the chamber 20, the controller controls the actuator 23 to moves the piston 21 in the direction of arrow 26 as shown in FIG. 4 to force the flow of hot gas 30 out of the duct 18, through the valve 14, through the duct 24, and finally through the duct 5 and into the processing chamber 1 via the holes in the panel 7 as shown in FIG. 2.

The sequence is repeated and the speed of the piston 21 can be adjusted to give higher or lower velocity bursts of hot inlet gas into the process chamber 1. Any combination of pulses can be programmed into the process cycle in relation to the position of rotation of the chamber 2 in the direction of arrows 27 and 28 as shown in FIG. 1.

For example, at any angle of the chamber 2 rotation, any number of pulses or bursts can be given for any given length of time, say for instance at 180 degrees rotation, many high power bursts of inlet gas can be induced for 10 minutes, and this can be repeated several times in a cycle. The intensity of the gas velocity can be increased or decreased as required by adjusting the speed of the movement of the piston 21 in the chamber 20.

Normal operation can be established at any time in between or at any part of the cycle by stopping the movement of the piston 21 in any position and either closing valves 13 and 15 together whilst opening valves 12 and 14 together, or by opening valves 13 and 15 together whilst closing valves 12 and 14 together, and thus effecting an instantaneous bypass by passing the gas through one side of the reservoir chamber 20 without moving the piston and thereby returning to what is regarded as the conventional process function. The time averaged flow of the outlet gas 29 is unaffected out of the duct 6 and 10 via the rotating joint 9 as the time averaged flow rate of gas is constant regardless of the operation of the piston 21 in the chamber 20.

The volume capacity of the chamber 20 can be as large as is practical to allow longer more frequent bursts of high velocity inlet gas 30 into the processing chamber 1, or alternatively can be smaller to allow short infrequent pulses of high velocity inlet gas 30 into the processing chamber.

Having a larger size volume in relation to the volumetric gas flow through the system allows greater flexibility and longer sustained bursts of high velocity inlet gas 30 can be achieved into the processing chamber 1.

The invention described hereinabove enables the time averaged volumetric gas flow to be maintained constant while allowing for the instantaneous variation of the inlet velocity of the gas to enhance the gasification/pyrolysis process by injecting the inlet hot gas further into the material being treated and thereby agitating it and increasing the surface area of material that contacts the hot gas. As described, the present invention may also be used with static treatment chambers and where used in such treatment chambers it will be appreciated that, to have maximum effect, the inlets through which the gas enters the treatment chamber will ideally be located so that the hot gas impinges directly on the material being treated.

Claims

1. A method of gasifying and/or pyrolysing material containing organic matter, the method comprising: introducing said material into a treatment chamber;heating said material by passing a flow of hot gas containing less than 8% oxygen by volume through said chamber so as to cause the material therein to pyrolyse or gasify;in a first mode of operation the gas is passed through the chamber at a first velocity;providing a means for temporarily increasing the velocity of the hot gas; andin a second mode of operation, temporarily increasing the velocity of the gas.

2. The method according to claim 1 wherein providing a means for temporarily increasing the velocity of the gas comprises: providing a reservoir vessel for the hot gas upstream of the treatment chamber;filling the reservoir vessel with hot gas at a first rate; and ejecting the hot gas from the reservoir at a second rate greater than the first rate.

3. The method according to claim 2 wherein the method comprises providing a reservoir vessel having a piston therein and an actuator for driving said piston and whereinejecting the hot gas comprises activating said actuator so as to move the piston to force hot gas from the reservoir vessel.

4. The method according to claim 3 wherein the vessel has an inlet and an outlet on either side of said piston, the method comprising opening one inlet on one side of the piston and opening one outlet on the opposite side of said piston; and in the first mode of operation moving said piston so that the instantaneous volumetric flow rate of the gas passing through the inlet is substantially equal to the instantaneous volumetric flow rate passing through the outlet.

5. The method according to claim 4 wherein in the second mode of operation the piston is moved at a speed greater than in the first mode of operation so as to force the air from the vessel through the outlet.

6. The method according to claim 5 wherein said piston is moved in a series of steps so as to provide a pulsed flow of hot gas through the outlet.

7. The method according to claim 3 wherein the vessel has an inlet and an outlet on either side of said piston, the method comprising, in a further mode of operation: opening the inlet and the outlet on the same side of the piston so as to provide a through flow through the vessel on one side of the piston.

8. The method according to claim 1 wherein the gas entering the processing chamber comprises less than 1% oxygen by volume and the material is pyrolysed.

9. An apparatus for gasifying and/or pyrolysing material containing organic matter, the apparatus comprising: a processing chamber for receiving material to be gassified;a processing chamber inlet for receiving hot gas;a processing chamber outlet for exhausting hot gas; andmeans for, in use, temporarily increasing the velocity of hot gas flowing into the inlet from a first velocity to a second higher velocity.

10. The apparatus according to claim 9 wherein said means for temporarily increasing the velocity of hot gas comprises: a reservoir chamber forming a cylinder and having a piston therein dividing the reservoir chamber into a first section and a second section;at least one reservoir inlet and at least one reservoir outlet;a drive means connected to said piston configured to drive said piston in said chamber; anda control means configured to control said drive means to selectively drive said piston in said reservoir so as to expel hot gas from said reservoir in an accelerated manner.

11. The apparatus according to claim 10 further comprising a first inlet and a first outlet in said reservoir chamber on one side of said piston and a second inlet and a second outlet in said reservoir chamber on the other side of said piston; and wherein the control means is configured to, in a first drive direction close the first outlet and the second inlet and operate the drive means so as to move the piston from the first inlet towards the second outlet so that hot gas flows into the first section and out of the second section.

12. The apparatus according to claim 11 wherein the control means is configured to, in a second drive direction open the first outlet and the second inlet, and close the first inlet and second outlet, and operate the drive means so as to move the piston from the second inlet towards the first outlet so that hot gas flows into the second section and out of the first section.

13. The apparatus according to claim 11 wherein, in a first mode of operation the controller is configured to operate the drive means to move the piston at a speed such that the instantaneous flow rate of the gas expelled from the reservoir is substantially equal to the instantaneous flow rate of the gas entering the reservoir.

14. The apparatus according to claim 13 wherein, in a second mode of operation the controller is configured to operate the drive means to move the piston at a speed such that the instantaneous flow rate of the gas expelled from the reservoir is greater than the instantaneous flow rate of the gas entering the reservoir.

15. The apparatus according to claim 14 wherein, in the second mode of operation the controller is configured to operate the drive means in a plurality of discreet steps such that the gas expelled from the reservoir is expelled in a plurality of accelerated bursts of gas.