ES2754363T3 - Improvements in waste treatment - Google Patents

Abstract

An apparatus for pyrolysing or gasifying material, which contains an organic content; the apparatus comprising: a furnace (10), mounted for rotation on at least one support (16), said furnace (10) having an inlet to receive hot gas, having a low or no oxygen content, to heat the material from its interior in order to treat it to produce synthesis gas, and an outlet for said synthesis gas; an electromagnet (28), arranged in or adjacent to said furnace (10), to create a magnetic field inside it; a plurality of ferrous elements (30), freely arranged inside the furnace (10); and a control means (32) for controlling the electromagnet (28) and the rotation of the furnace (10) so that, when said electromagnet (28) is activated, it retains said ferrous elements (30) as the furnace (10 ) broken; characterized in that the apparatus further comprises at least one gas analyzer (26), configured to analyze the composition of the gas leaving said furnace (10); and wherein the control means (32) is configured to receive signals from said gas analyzer (26), and when said signals indicate that the treatment of the material in said furnace (10) has been substantially completed, controlling the electromagnet (28 ) to release the ferrous elements (30), when they are substantially at the top of the rotation of the furnace.

Description

DESCRIPTION

Improvements in waste treatment

This invention relates to the treatment of organic materials, in particular, this invention relates to improvements in the gasification and / or pyrolysis treatment of materials having an organic content.

Gasification and pyrolysis of organic matter are known techniques, in which the material is heated in the absence of oxygen (pyrolysis) or in a low oxygen environment (gasification) to produce synthesis gas. An example of this is found in waste from energy systems, in which waste material, for example municipal solid waste, is pyrolyzed / gasified to produce a synthesis gas, which is then used to generate electricity. However, when material having a large amount of low calorific organic material is pyrolyzed, for example wood (in contrast to materials such as plastics which have a high calorific value), a carbonic residue is left which is a residue. carbonaceous or a coke-like substance which is collectively referred to herein as carbonaceous residue.

Once the pyrolysis reaction is complete this carbonaceous residue still contains a large amount of unrecovered energy. This can be recovered by increasing the oxygen content to a level sufficient for gasification of the carbonaceous residue to occur without combustion (approximately 3% to 12% by volume of the oxygen content). However, gasification can take some time and is added to the total waste treatment time reducing the overall treatment efficiency.

EP0822374 describes a rotary drum pyrolysis reactor having iron balls arranged inside it with the gas inlet suitable for the introduction of hot gas with little or no oxygen content and a gas outlet suitable as outlet for the synthesis gas produced.

US4676439 describes a ball mill consisting of a rotating drum that rotates around an axis that has ferromagnetic balls inside, where the electromagnets are located around the outer wall of the rotary reactor, which are controlled so that they catch the balls Metal balls at a lower position of the rotating drum, lift the metal balls as the reactor rotates and release the metal balls near the upper position of the rotating drum, causing the metal balls to fall in a parabolic arc to the bottom of the reactor causing a high impact grinding action.

The present invention aims to reduce the overall time of waste treatment by pyrolysis / gasification.

In accordance with a first aspect of the present invention, there is provided an apparatus for pyrolyzing or gasifying material having an organic content; the apparatus comprising: a furnace mounted for its rotation on at least one support, said furnace having an inlet to receive hot gas that has little or no oxygen content to heat the material inside it in order to treat it to produce gas of synthesis and an outlet for said synthesis gas; an electromagnet arranged in or adjacent to said oven to create a magnetic field therein; a plurality of ferrous elements freely arranged within the furnace; and a control means for controlling the electromagnet and oven rotation; wherein when said electromagnet is activated, it retains said ferrous elements as the furnace rotates, wherein the apparatus further comprises at least one gas analyzer configured to analyze the composition of the gas leaving said furnace; and where the control means is configured to receive signals from said gas analyzer and when said signals indicate that the treatment of the material in said furnace has been substantially completed, controlling the electromagnet so that it releases the ferrous elements when they are substantially in the part top of oven rotation.

The oven may further comprise a first portion and a second portion, wherein said first portion is disposed above said second portion in a first rotary position and wherein said second portion is disposed above said first portion in a second rotary position; wherein said control means is configured to control the oven to rotate it between the first position and the second position.

The control means may be configured to activate the electromagnet to retain the ferrous elements as the furnace rotates between the second rotary position and the first rotary position. In one arrangement, the electromagnet may be located in the first portion and the control means is configured to deactivate the electromagnet in the first position so that the ferrous elements fall, under the influence of gravity, in the second portion and in another arrangement the electromagnet may be located in the second portion and the control means is configured to deactivate the electromagnet in the second position so that the ferrous elements fall, under the influence of gravity, in the first portion.

In this way, the ferrous elements can fall from above onto the carbonaceous residue, which will be at the lowest point of the rotary kiln due to gravity and will break the carbonaceous residue into smaller pieces. This increases the surface area of the carbonaceous residue which increases the speed at which it is treated.

The apparatus comprises at least one gas analyzer to analyze the composition of the gas leaving said oven. As described below, by analyzing the gas leaving the furnace, the point reached by the treatment of the material in the furnace can be determined, and in particular, it can be determined when most of the furnace material has been treated. The control means is configured to receive signals from the gas analyzers and when said signals indicate that the treatment of the material in said furnace has been substantially completed, the control means controls the electromagnet to release the ferrous elements when they are substantially in the top of the oven rotation. The control means can optionally also increase the oxygen content of the furnace at this stage to gasify the carbonaceous residue inside.

Ferrous elements can have a mass of at least 500 g. Optionally, the ferrous elements can have a mass of at least 1 kg. The ferrous elements comprise steel and / or can be substantially spherical. Optionally, the ferrous elements can have one or more grooves on their surface.

In accordance with a second aspect of the present invention, there is provided a method of pyrolysis and / or gasification of material having an organic content; the method comprising: providing an oven mounted for rotation on at least one support, said oven having an inlet and an outlet; supplying a flow of hot gas having little or no oxygen content to the furnace through the inlet to heat the material therein in order to treat it to produce synthesis gas; providing an electromagnet disposed in or adjacent to said furnace to create a magnetic field therein; providing a plurality of freely arranged ferrous elements within the furnace; and activating said electromagnet to retain said ferrous elements as the furnace rotates, wherein the method further comprises analyzing the composition of the gas leaving said furnace to determine when the material treatment in said furnace has been substantially completed and when said process is substantially complete, controlling the electromagnet to release the ferrous elements when they are substantially at the top of the furnace rotation.

The oven may comprise a first portion and a second portion, and the method may further comprise: controlling the oven to rotate between a first rotary position where the first portion is arranged above said second portion and a second rotary position on the that said second portion is arranged on top of said first portion. In one arrangement, the electromagnet may be located in the first portion and the method further comprises activating the electromagnet to retain the ferrous elements as the furnace rotates from the second rotary position to the first rotary position. The method further comprises deactivating the electromagnet in the first rotary position so that the ferrous elements fall, under the influence of gravity, in the second portion. In an alternative arrangement, the electromagnet is located in the second portion and the method may comprise activating the electromagnet to retain the ferrous elements as the furnace rotates from the first rotary position to the second rotary position. The method further comprises deactivating the electromagnet in the second position so that the ferrous elements fall, under the influence of gravity, in the first portion.

The method comprises analyzing the composition of the gas that comes out of said oven. By analyzing the composition of the gas leaving said furnace, it can be determined when the treatment of the material in said furnace has been substantially completed. The method further comprises, when said process has been substantially completed, controlling the electromagnet to release the ferrous elements when they are substantially at the top of the furnace rotation. The method may comprise, when the treatment of the material in said furnace has been substantially completed, increase the oxygen content of the furnace. Increasing the oxygen content of the furnace may comprise increasing the oxygen content of the furnace at a volumetric flow rate of between 3 and 12%

Specific embodiments of the invention are described below, without limitation, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic diagram of an apparatus of the invention;

Figure 2 shows a side view of an apparatus of the invention;

Figures 3-5 show the operation of the invention; and

Figure 6 shows an example of a ferrous element for use in the invention.

Referring to Figures 1 and 2, an oven 10 is shown comprising a first portion 12 and a second portion 14. The second portion 14 is removable from the first portion 12 for loading and unloading the material to be treated in the oven 10.

The oven is pivotally mounted on two mounts 16 and a drive 18 is provided to rotate the oven between a first rotary position where the first portion 12 is on top of the second portion 14 and a second rotary position where the second portion 14 is on top of first portion 12.

A supply of hot gas to the furnace is provided through conduit 20 from a supply of hot gas 22, and exits the furnace through an additional conduit 24. A gas analyzer 26 is provided to analyze the composition of the gas leaving the oven. The gas analyzer can measure one or more of: hydrogen content, carbon monoxide content and carbon dioxide content of the gas.

An electromagnet 28 is provided in the oven. The electromagnet can be provided in either the first or second portion of the oven and is shown in Figure 1 in the first portion for illustrative purposes. A plurality of ferrous elements 30 are provided in the furnace. The ferrous elements are described in more detail below in connection with Figure 6.

With reference to Figures 3 to 5, the operation of the oven is shown.

A batch of the material to be treated is loaded into the furnace and hot gas, which is substantially oxygen-free, passes through the furnace as it rotates to pyrolyze the material within. As the material is pyrolyzed, hydrogen and carbon monoxide are released from the furnace through the outlet duct 24. The gas analyzer 26 monitors the composition of the gas as it leaves the furnace and sends signals to the controller 32. Once the controller determines that the signals from the gas analyzer indicate that the pyrolysis of the material is about to complete, it increases the amount of oxygen in the gas so that the reaction in the chamber changes from pyrolysis to gasification. The controller may respond to, for example, a drop below a specific threshold value of the level of hydrogen or carbon monoxide in the gas leaving the furnace.

At this stage of treatment, when most of the furnace material has been pyrolyzed, a residue 34 containing inert material and a carbonic residue formed from the pyrolysis of low calorific value organic material will remain in the furnace. As the furnace rotates, the electromagnet is activated so that the ferrous elements 30 are attracted and retained as the furnace rotates to the first position (Figure 3). When the furnace reaches this position, the electromagnet 28 is deactivated and, therefore, the ferrous elements are released and fall from the top of the furnace to the bottom of the furnace, where they will collide with the carbonaceous residue and due to their mass and The fragile nature of the carbonaceous residue will break or crush into smaller pieces (Figure 4).

Then, the furnace rotates from the second first position to the second position (Figure 5) and then, the electromagnet 28 is activated again to attract and retain the ferrous elements. The oven then continues to rotate back to the first position (Figure 3) and the process is repeated. Once the gas analyzers show that the gasification reaction is substantially complete the process is over, the furnace returns to the first position and the second portion 14 is removed, emptied, and refilled with a fresh batch of material.

Breaking the carbonaceous residue into smaller pieces increases its available surface area to react with oxygen from the hot gas passing through the furnace, thereby reducing the time it takes to gasify the carbonaceous residue.

Decreasing the total treatment time increases the efficiency of waste treatment by reducing the amount of time it is necessary to provide the hot gas. The gas released as synthesis gas can be used for energy production and consequently, by reducing the amount of energy that needs to be used to produce the hot gas (by reducing the amount of time the hot gas is needed) it increases the overall percentage of recovered energy that is available for export.

Referring to Figure 6, an example of a ferrous element for use in the apparatus is shown. Element 30 has a substantially spherical shape and is made of ferrous steel. Each element preferably weighs more than 500 g and elements that have a mass of 1 kg or more can be beneficial in crushing the carbonaceous residue. As can be seen, the element has a series of grooves 36 around its edge that divide the surface into a plurality of raised shapes 38. These raised shapes improve friction as the items impact the carbonaceous residue and help prevent they deflect when bouncing off large chunks, most likely if the elements have a smooth spherical outer surface. It will be appreciated that any surface that produces this effect can be used and the ferrous elements are not limited to the shapes shown.

Claims (12)

1. An apparatus for pyrolyzing or gasifying material, containing an organic content; comprising the apparatus: an oven (10), mounted for its rotation on at least one support (16), said oven (10) having an inlet to receive hot gas, which has little or no oxygen content, to heat the material inside with in order to treat it to produce synthesis gas, and an outlet for said synthesis gas; an electromagnet (28), arranged in or adjacent to said oven (10), to create a magnetic field therein; a plurality of ferrous elements (30), freely arranged within the furnace (10); and a control means (32) for controlling the electromagnet (28) and the rotation of the furnace (10) so that, when said electromagnet (28) is activated, it retains said ferrous elements (30) as the furnace (10) ) broken; characterized in that the apparatus further comprises at least one gas analyzer (26), configured to analyze the composition of the gas leaving said oven (10); and wherein the control means (32) is configured to receive signals from said gas analyzer (26), and when said signals indicate that the treatment of the material in said oven (10) has been substantially completed, control the electromagnet (28) to release the ferrous elements (30), when they are substantially at the top of the furnace rotation. 2. The apparatus according to claim 1, wherein the oven (10) further comprises a first portion (12) and a second portion (14), wherein said first portion (12) is disposed above said second portion (14) in a first rotary position, and wherein said second portion (14) is disposed on top of said first portion (12) in a second rotary position; wherein said control means (32) is configured to control the oven (10) to rotate it between the first position (12) and the second position (14). 3. The apparatus according to claim 2, wherein the electromagnet (28) is located in the first portion (12) and the control means (32) is configured to deactivate the electromagnet (28) in the first position of so that the ferrous elements (30) fall, under the influence of gravity, in the second portion (14). The apparatus according to claim 3, wherein the control means (32) is configured to activate the electromagnet (28) in order to retain the ferrous elements (30) as the furnace (10) rotates from the second rotary position to the first rotary position. 5. The apparatus according to claim 2, wherein the electromagnet (28) is located in the second portion (14) and the control means (32) is configured to deactivate the electromagnet (28) in the second rotary position , so that the ferrous elements (30) fall, under the influence of gravity, in the first portion (12). The apparatus according to claim 5, wherein the control means (32) is configured to activate the electromagnet (28), to retain the ferrous elements (30), as the furnace (10) rotates out of the first rotary position to the second rotary position. The apparatus according to any of the preceding claims, wherein the ferrous elements (30) have one or more grooves (36) on their surface. 8. A method of pyrolysis and / or gasification of material, containing an organic content; understanding the method: providing an oven (10), mounted for rotation on at least one support (16), said oven (10) having an inlet and an outlet; providing a flow of hot gas, having little or no oxygen content, to the furnace (10) through the inlet to heat the material therein in order to treat it to produce synthesis gas; providing an electromagnet (28), arranged in or adjacent to said furnace (10), to create a magnetic field therein; providing a plurality of ferrous elements (30), freely arranged within the furnace (10); and activating said electromagnet (28) to retain said ferrous elements (30) as the furnace (10) rotates; and characterized by that The method further comprises analyzing the composition of the gas leaving said furnace (10) to determine when the treatment of the material in said furnace (10) has been substantially completed; and when said process is substantially completed, control the electromagnet (28) to release the ferrous elements (30), when they are substantially at the top of the furnace rotation. The method according to claim 8, wherein the oven (10) comprises a first portion (12) and a second portion (14), the method further comprising: controlling the oven (10) to rotate between a first rotary position, where the first portion (12) is arranged above said second portion (14) and a second rotary position, where said second portion (14) is arranged above said first portion (12). The method according to claim 9, wherein the electromagnet (28) is located in the first portion (12), and the method further comprising activating the electromagnet (28) to retain the ferrous elements (30), as the furnace (10) rotates from the second rotary position to the first rotary position and, optionally, deactivating the electromagnet (28) in the first rotary position, so that the ferrous elements (30) fall, under the influence of gravity, in the second portion (14). The method according to claim 10, wherein the electromagnet (28) is located in the second portion (14), and the method comprising activating the electromagnet (28) to retain the ferrous elements (30) as the furnace (10) rotates from the first rotary position and the second rotary position and, optionally, deactivates the electromagnet (28) in the second position, so that the ferrous elements (30) fall, due to the influence of gravity, on the first portion (12). 12. The method according to any one of claims 8 to 11, wherein the method further comprises: analyzing the composition of the gas leaving said furnace (10) to determine, when the treatment of the material in said material has been substantially completed oven (10) by pyrolysis; and when said pyrolysis process is substantially completed, increase the oxygen content of the furnace (10).