Field of the invention

The invention relates to an apparatus for thermally treating organic material in order to separate carbon from organic material as defined in the preamble of the independent claim 1.

The invention also relates to a method for using an apparatus according to claims 1 to 8.

The background of the invention is in the method for producing biocarbon and the present invention provides an apparatus for the method for producing said biocarbon. The apparatus is called a carbonizer because the method aims for the maximization of charcoal. Although the process can be adapted to maximize vapors or heat developing during the process, the apparatus can still be called as carbonizer. The carbonizer is based on a pyrolysis reaction where organic material is fed into the carbonizer and treated by in dry distillation. During pyrolysis the organic material undergoes changes in a process where the material is heated to around 450 - 600 ⁰ C in the absence of air and the organic material is in the carbonizer approximately 10 - 20 minutes such that the process yields charcoal, pyrolysis gases and organic vapors. The time depends on the raw material that is used and its moisture content. The operation of the process is continuous and energy efficient. The gas that develops in the pyrolysis process is burned to create energy for the process itself. The organic vapors can be condensed to bio-oil. The bio-oil can be further refined into pitch.

Different types of pyrolysis reactors are known in the prior art. One type of pyrolysis reactor is a reactor that has no solid movement through the reactor during the pyrolysis process. Other types of reactors work with solids that move through the reactor. Those kind of reactors have solved the movement requirement in different ways, one having a moving bed, the other causing the movement by mechanical forces and the third causing the movement by fluid flow. Pyrolysis reactors can supply heat also different ways, for example by burning the raw material inside the reactor or by using direct heat transfer from hot gases produced by combustion of one or more of the pyrolysis products or any other fuel outside the reactor or by using indirect heat transfer through the reactor walls having an external heat source.

A heated screw fed converter, called Thompson Converter is known in the prior art. The Thompson Converter consists of at least one metal tube heated externally where the raw material is conveyed through said at least one heated metal tube by means of screws in a longitudinal direction of the process chamber such that the raw material gets carbonized during the process. When the raw material is carbonized during the movement through the process chamber the carbonized material will be removed in the end of the converter and passed to a collecting conveyor which moves the carbonized material out of the process chamber. The pyrolysis gases that are developed during the process are conveyed inside the screw from the end part of the screw toward the starting point where the raw material enters to the screw. The volatile gases are fed back into the burner such that the operation becomes self sustained. The combustion gas is removed from the process chamber through a discharge outlet, such as a stack.

JP 2006274201 A discloses a continuous reduced-pressure drying carbonization apparatus in which a liquid containing waste material is dried and carbonized. The apparatus comprises a carbonization chamber and a heating furnace where the carbonization chamber is formed of multiple screw kneading machines which are mutually connected. This means that they are connected in series such that the waste material goes through all the kneading machines before it is removed from the apparatus. The heating furnace is a combustion heating furnace equipped with the combustion apparatus where the combustion apparatus is a kerosene burner. The heating furnace is equipped with a heating zone formed on the upper part of the heating furnace and a heat source zone in the lower part of the heating furnace in which a burner tip of the combustion apparatus is arranged at a side wall protrusion part of the heat source zone.

Objective of the invention

The object of the invention is to provide an effective apparatus for producing biocarbon which is in addition self-sustaining. The object of the invention is also to provide advantageous methods for using said apparatus.

Short description of the invention

The apparatus of the invention is characterized by the definitions of the independent claim 1.

Preferred embodiments of the apparatus are defined in the dependent claims 2 to 8.

The method for using the apparatus is characterized by the definitions of the claims 9 to 11 and preferred embodiment of the method is defined in the dependent claim 12.

The invention provides an apparatus for producing biocarbon. The apparatus, i.e. the carbonizer, separates carbon from the incoming organic material by treating it thermally. The carbonizer comprises a combustion chamber for thermal treatment of organic material, said combustion chamber comprising a combustion apparatus for heating said combustion chamber, conveyor means for conveying organic material during thermal treatment of organic material, said conveyor means extending through the combustion chamber from the outside of the combustion chamber and to the outside of the combustion chamber and being closed from the combustion chamber, said conveyor means being configured for distributing heat from the combustion chamber to the organic material such that the organic material is thermally treated, said conveyor means being configured for conveying also pyrolysis gas developed during said thermal treatment. The carbonizer also comprises feeding means for receiving organic material and for feeding said organic material to the conveyor mean, said feeding means is arranged outside of the combustion chamber and removal means for removing the thermally treated organic material from the conveyor means to a next phase.

The combustion chamber acts as a reactor where the thermal treatment happens, although inside the conveyor means. The carbonizer also comprises a gas burner arrangement for arranging a flame to the combustion chamber. The organic material is conveyed in the carbonizer by conveyor means which is arranged in a closed access system in a longitudinal direction inside the combustion chamber. The gas burner heats the combustion chamber and the organic material undergoes thermal treatment during the movement through the combustion chamber inside the conveyor means. The conveyor means is preferably a screw conveyor but other type of conveyor means are also possible, for example a mixing worm which mixes the material inside the conveyor can be used. During the thermal treatment pyrolysis gas is released and it is arranged to move inside the conveyor means preferably to the opposite direction than the organic material. Pyrolysis gas is lead inside the conveyor means as a return flow toward the feeding means, i.e. toward the incoming end of the conveyor means where the organic material is fed to the conveyor means and the gas is redirected outside the combustion chamber to a pipeline through which it flows to a combustion apparatus such as a gas burner. In other words a pipeline is arranged outside of the combustion chamber for conveying pyrolysis gas coming through the conveyor means and from the conveyor means through the pipeline to the combustion apparatus such that the pyrolysis gas cools down and is burned in the combustion apparatus for creating heat inside the combustion chamber. The pyrolysis gas is configured to be conveyed continuously during thermal treatment from the conveyor means to the combustion apparatus. The pyrolysis gas is burned in the combustion apparatus, i.e. in the gas burner continuously during the operation of the apparatus and the combustion apparatus is arranged to create a flame inside the combustion chamber such that it heats the walls of the combustion chamber and radiates heat to the conveyor means. In other words the flame radiates heat inside the combustion chamber and toward the conveyor means. The flame of the gas burner heats the side walls of the combustion chamber and both the heat from the walls as well as the radiation heat coming from the flame heats the conveyor means in which the organic material moves and becomes thermally treated. The combustion gas is lead to a discharge outlet and the thermally treated organic material is removed from the conveyor means through removal means in the end of the conveyor means. The removal means is preferably arranged outside of the combustion chamber. The pyrolysis gas moving inside the conveyor means heats the incoming organic material coming against pyrolysis gas and at the same time pyrolysis gas cools down. While pyrolysis gas heats the incoming organic material most of the particles of pyrolysis gas are absorbed to the organic material. Pyrolysis gas flows with its own pressure through the pipeline from the conveyor means to the combustion apparatus because it tries to get to a lower pressure.

When pyrolysis gas is formed in the process space, i.e. in the conveyor means, it contains tar and when pyrolysis gas flows out of the conveyor means and toward the combustion apparatus the tar is preferably separated from the pyrolysis gas. The pyrolysis gas is processed by a separation arrangement before it is burned in the combustion chamber. The tar separated from pyrolysis gas is used for example to produce carbon briquettes from the thermally treated organic material by grinding it and mixing therein tar separated from the pyrolysis gas and compressing these ingredients into briquettes. Pyrolysis gas formed by heat transfer from the process space into the organic matter to be processed contained in the conveyor means is conveyed into the combustion chamber provided in the process space for combustion of the gas, the combustion gas formed in the combustion chamber is discharged from the process space by means of a discharge outlet in the upper part of the combustion chamber and the thermally treated carbonized matter is discharged from the conveyor means for further processing. To separate the tar contained in the pyrolysis gas formed in the process space the gas is processed before combustion in the combustion chamber by a separation process. As a preferred embodiment of the separation of tar the pyrolysis gas is preferably cooled for example by a heat exchanger arrangement before being fed to a separation arrangement. In a further embodiment the tar contained in the pyrolysis gas is separated by an electrostatic precipitator (ESP). As a yet further embodiment the pyrolysis gas is cooled to about 30 ⁰ C before being fed to a separation arrangement.

The conveyor means is preferably arranged substantially air tight in respect of the environment and it continuously conveys the organic material coming from the feeding means to the conveyor means and through the conveyor means. The organic material moving through the conveyor means undergoes thermal treatment such that all the material is thermally treated by heat radiating from the combustion chamber through the walls of the conveyor means. The organic material is preferably mixed inside the conveyor means for ensuring that the heat reaches all the material. The feeding means regulates the material flow to the conveyor means such that the organic material level inside the conveyor means is not too high or on the other hand the level is not too low. If there is too much material in the conveyor means there is a risk that all the material will not be treated thermally. If the material level is too low there is a risk that the material becomes over-carbonized. The regulation can also be accomplished in the conveyor means such that the blades of the conveyor are in different distances or the diameter of the conveyor means changes. One main feature of the conveyor means is that it rotates so that the organic material is completely mixed inside the conveyor means and the organic material is totally carbonized during the movement through the conveyor means so that there won't be any over- carbonized material on the down side of the conveyor means and some raw material inside the material bedding. One possible conveyor means is a double screw conveyor where the screws work imbricated. The conveyor means has a shaft which is mounted on a bearing on both ends. The conveyor means is preferably supported by one or more supports, such as beams, so that the supports preferably are arranged to go through the combustion chamber in a cross direction of the combustion chamber, i.e. in a lateral direction of the combustion chamber.

The combustion chamber comprises one or more conveyor means, preferably arranged parallel such that they all extend in a longitudinal direction through the combustion chamber. The combustion chamber also comprises at least one combustion apparatus that produces heat to the combustion chamber. The conveyor means is preferably arranged to the upper part of the combustion chamber so that the flame coming from the combustion apparatus that is arranged preferably to the lower part of the combustion chamber is not touching the conveyor means. The flame is preferably directed to the longitudinal direction of the combustion chamber toward the opposite wall to which the combustion apparatus is pointed. The conveyor means is arranged air-tight so that the organic material is heated in an oxygen-free space.

The combustion chamber is preferably a big box-like structure having conveyor means going through the combustion chamber in the upper part of the combustion chamber such that the conveyor means extend from the outside of the combustion chamber through the combustion chamber and to the outside of the combustion chamber. The conveyor means is preferably arranged to the combustion chamber in a longitudinal direction such that the conveyor means comes out from the combustion chamber in the opposite side of the combustion chamber than where it goes in, i.e. the conveyor means ends in the opposite site of the combustion chamber than where it starts.

The combustion apparatus gets pyrolysis gas through the pipeline from the conveyor means and an additional air from the combustion air blower. The pyrolysis gas and the additional air are mixed and burned inside the combustion apparatus in order to create a flame to the combustion chamber. The additional air creates overpressure to the combustion chamber so that the combustion gases run out of the combustion chamber through a discharge outlet which is preferably in the upper part of the combustion chamber.

The combustion chamber is preferably isolated with a 200 - 250 mm thick isolation layer. The apparatus, i.e. the carbonizer, is arranged to work in overpressure.

An electric filter is arranged between the combustion chamber and the discharge outlet so that the ash and smut particles can be removed from the combustion gas so that tar and hydrocarbon aerosols can be recovered.

The apparatus of the invention can be used in many ways in order to get different end products. One method for using the apparatus is to control the amount of organic material fed to the conveyor means by the feeding means for maximizing the separation of carbon from organic material configured to go through thermal treatment. The feeding means is arranged to feed an optimum amount of organic material depending on the process parameters, for example the time organic material is spending in the conveyor means or the temperature in which the thermal treatment is arranged to happen. The aim is to get all the organic material carbonized during the movement inside the conveyor means. Another method for using the apparatus is that the conveyor means is arranged to convey organic material in such a speed that organic material is configured to be gasified for maximizing the amount of pyrolysis gas coming through the conveyor means. This means that the process time is long and the organic material moves preferably quite slowly in the conveyor means or the amount of organic material inside the conveyor means is small so that all the organic material is carbonized and even further at least partly gasified. The excess gas can be used in other purposes such as for burning in other apparatuses. Yet another method for using the apparatus is to create thermal energy in the combustion chamber by burning pyrolysis gas developed during thermal treatment and part of the thermal energy is transferred from the apparatus for example to heat spaces etc. Even more thermal energy than is needed can be created to develop pyrolysis gas. List of figures

In the following the invention will be described in more detail by referring to the figure, in which

Fig 1 shows an apparatus for thermally treating organic material in order to separate carbon as of one preferred embodiment of the invention.

Detailed description of the invention

The figure 1 shows an example of the apparatus 1 for thermally treating organic material in order to separate carbon from organic material. The apparatus 1 comprises a combustion chamber 5 for thermal treatment of organic material and the combustion chamber 5 comprises a combustion apparatus 7 for heating said combustion chamber 5. The apparatus also comprises conveyor means 3 for conveying organic material during thermal treatment of organic material, said conveyor means 3 extending through the combustion chamber 5 from the outside of the combustion chamber 5 and to the outside of the combustion chamber 5 and the conveyor means 3 is closed from the combustion chamber 5. The conveyor means 3 is configured for distributing heat from the combustion chamber 5 to the organic material such that the organic material is thermally treated. The conveyor means 3 is configured for conveying also pyrolysis gas developed during said thermal treatment. The pyrolysis gas is preferably arranged to move inside the conveyor means 3 as a return flow toward feeding means 2. The apparatus comprises also feeding means 2 for receiving organic material and feeding said organic material to the conveyor means 3, said feeding means is arranged outside of the combustion chamber 5 and removal means 4 for removing the thermally treated organic material from the conveyor means 3. A pipeline 8 is arranged outside of the combustion chamber 5 for conveying pyrolysis gas coming through the conveyor means 3 outside of the combustion chamber 5 and from the conveyor means 3 through said pipeline 8 to the combustion apparatus 7 such that the pyrolysis gas cools down and is burned in the combustion apparatus 7 for creating heat inside the combustion chamber 5. Pyrolysis gas is configured to be conveyed by the pipeline 8 from the conveyor means 3 to the combustion apparatus 7 via a separation arrangement 11 for separating tar from pyrolysis gas. In other words, pyrolysis gas is processed by a separation arrangement 11 for separating tar contained in the pyrolysis gas before pyrolysis gas is burned in the combustion chamber 5. The conveyor means 3 begins from the outside of the combustion chamber 5 such that when the organic material arrives to the conveyor means 3 through feeding means 2 it does not immediately be exposed to thermal treatment. The conveyor means 3 is arranged to go through the combustion chamber 5 such that during the travel in the area of the combustion chamber 5 the organic material is thermally treated inside the conveyor means 3. On the other end of the conveyor means 3 the thermally treated organic material is removed from the conveyor means 3 through removal means 4. While the organic material is thermally treated the pyrolysis gas is developed inside the conveyor means 3 and it moves as a return flow inside the conveyor means 3 toward the beginning of the conveyor means 3. A pipeline 8 is arranged in flow communication between the conveyor means 3 and the combustion apparatus 7 such that the pyrolysis gas coming from the conveyor means 3 is moved along the pipeline 8 to the combustion apparatus 7 where it is burned in order to create a flame inside the combustion chamber 5 to heat the combustion chamber 5 and radiate heat to the conveyor means 3 for thermally treating organic material conveyed inside the conveyor means 3. The combustion gas is lead to a discharge outlet 6. The combustion apparatus 7 is arranged to create a flame inside the combustion chamber 5 such that it heats the walls of the combustion chamber 5 and radiates heat to the conveyor means 3. The pyrolysis gas is continuously during thermal treatment conveyed from the conveyor means 3 to the combustion apparatus 7 through the pipeline 8. The apparatus 1 according to the invention works in overpressure. The conveyor means 3 is preferably supported by one or more supports 9 going through the combustion chamber 5 in a lateral direction of the combustion chamber 5. The conveyor means 3 comprises preferably a shaft and pyrolysis gas is arranged to move inside the conveyor means 3 near the shaft and/or near the upper part of the conveyor means 3. The combustion chamber 5 is preferably arranged in a box-like structure 10.

It is apparent to a person skilled in the art that as technology advanced, the basic idea of the invention can be implemented in various ways. The invention and its embodiments are therefore not restricted to the above examples, but they may vary within the scope of the claims.