CONTINUOUSLY OPERATING PYROLYSIS EQUIPMENT AND METHOD TO PERFORM PYROLYSIS PROCESS

Abstract

The continuously operating pyrolysis equipment that consists at least of the feeding apparatus to feed the raw material into the reactor, the reactor to produce the pyrolysis products, the heating system to generate the heat energy that is needed in the pyrolysis process and to transfer it into the raw material, the mixing apparatus and the conveyor to mix the raw material particles advancing in the reactor and to transport them from there, and the channels to exit the solid, the liquid, and the gas pyrolysis products from the reactor and where the feeding apparatus includes the liquid seal to maintain an essentially oxygen-free condition in the reactor. The mentioned feeding apparatus includes at least: the push button to push the lighter than the liquid seal liquid raw material particles from the feeding apparatus feeding channel under the fluid surface of the fluid seal, the second conveyor leading from the liquid above the surface of the fluid to transport and lift the lighter than the fluid raw material particles to the surface of the liquid in the transfer channel and the first conveyor to lift the heavier than the liquid raw material particles from the liquid into the feeding channel and to transport them and to the surface of the liquid gotten raw material particles to the reactor feeding opening.

Description

The object of this invention is continuously operating pyrolysis equipment that composes at least of a feeding apparatus to feed raw material into the reactor, a reactor to produce the pyrolysis products, a heating system to produce the necessary heat energy needed by the pyrolysis process and to transport into the material in the reactor, a mixing apparatus and conveyor to mix and transport the raw material particles that advance in the reactor in the pyrolysis process, and channels to remove solid, liquid, and gas pyrolysis products from the reactor and which mentioned feeding apparatus has a liquid seal to maintain essentially an oxygen free condition in the reactor. The object of the invention is also the method to perform the pyrolysis process.

The intention of the invention is to make possible the advantageous chemical recycling of the plastic waste so that also the mixed polyolefin rich plastic waste can be handled and recycled in the pyrolysis process either alone or together with for example rubber waste. One product that is produced in this process is oil that can be used after continuation processing as the raw material of the monomers in the plastic industry.

The applications of the invention are the pyrolysis processes where using the before mentioned plastic waste gas, liquid, and solid pyrolysis products are produced. In these processes that are typically performed in the temperature of approximately 400-500° C. the polymers of the raw materials are chopped in an oxygen-free condition into gas hydrocarbons and using them pyrolysis oil is made by condensing. Also uncondensed gas is created in the process, which is pyrolysis gas, that consists of short chain hydrocarbons and hydrogen gas and that is used in the energy production of the process. In the mentioned pyrolysis processes, also solid pyrolysis products are formed that contain mainly carbon and inorganic compounds. The quality of the formed solid products depends on the raw material and they can be used for instance in asphalt or pigment raw material or continue treated as (recycle) carbon black the English name of which is known “carbon black”.

The first advantageous application example of the invention can be seen to be the continuously operating pyrolysis process where there is a liquid seal in the raw material feeding apparatus that can knowingly maintain essentially an oxygen-free condition in the reactor.

The second advantageous application example can be seen to be the pyrolysis process that fulfills the before mentioned conditions where all the heat energy that is fed into the reactor is produced in one equipment like boiler, heat generator, or corresponding equipment.

The third advantageous application example can be seen to be a pyrolysis process that fulfills some of the previous conditions where the raw material particles are treated more efficiently than now so that their charred isolating surfaces do not prevent or slow the pyrolysis reaction of their inner parts.

In the first one of the before mentioned application examples it is dealt in accordance with the known technique among other things so that the density of the raw material particles lighter than liquid of the liquid seat is risen higher than the mentioned liquid by a certain preliminary treatment so that also they can be made to sink to the liquid seal bottom extended conveyor that transports them with initially heavier than the liquid raw material particles to the feeding opening of the reactor. By the lighter material than the liquid seal material is meant in this document of its density (e.g. kg/dm³ lower density material and by heavier material a material of higher density.

In the Finnish patent publications F1126675 B and E1128105 B there have been presented the feeding apparatuses equipped with the liquid seal that do not include the equipments to get the raw material particles that are lighter than the liquid of the liquid seal to the conveyor that leads from the liquid seal to the feeding opening of the reactor. The drawback of these known solutions is just that the lighter than the liquid particles remain to the surface of the liquid if they are not gotten heavier than the liquid by a preliminary treatment. The preliminary treatment is disadvantageous and increases the costs of the process.

In the second mentioned application example the known technique procedure is among other things that in a boiler or other heat generator generated heat energy is lead to the wall of the reactor without dividing it in different intensities in different zones.

In the international patent publication WO202118622 A1 there has been presented a heating system of a pyrolysis reactor where in around the reactor adapted chamber burning substance is burned and the generated heat energy heats the reactor shell as a general area so that the heat energy is distributed evenly to the reactor. The drawback of this solution is different heat energy amounts being directed to different parts of the reactor. The different phases of the pyrolysis process require different amounts of energy but this solution does not obtain it.

One known way to heat the reactor is to form numerous heat energy areas and to set for each area its own heat element.

In the US patent publication US20190300794 A1 there has been presented in sections divided heating system where each section has its own heating element. The drawback of this solution is that numerous heating equipments are needed and thus the heat generation cannot be concentrated in one equipment. This is disadvantageous economically.

The third mentioned usage example situation the known technique procedure is among other things to set a screw conveyor to the reactor where the screw element while rotating pushes the raw material forwards or then a bull chain conveyor is adapted to the reactor to move the raw material forwards.

In the Finnish patent publications FI126675 B and Fil28105 B there have been presented solutions where the first mentioned has a screw conveyor and the second mentioned has a bull chain conveyor. The biggest drawback of these solutions can be seen to be that they move the raw material as bunches so that the pressure is not directed to the particles which would break their skin and get their inner parts more efficiently targeted by the heat energy. As mentioned earlier before the charring of the surfaces of the raw material particles in the pyrolisis process creates an efficient isolation layer to the surfaces of the particles that prevents the heat energy to get inside them.

The intention of this invention is to obtain such a continuously operating pyrolisis equipment and method to perform pyrolysis process that avoids drawbacks that exist in the known technique. It is characteristic for the solution according to the invention what has been stated in the characterizing parts of the claims 1 and 9.

The advantage of the pyrolysis equipment including the liquid seal according to the invention in relation to the known technique is:

• • i. the raw material does not need the preliminary treatment for the lighter than liquid seal liquid particles to get them under the liquid surface and further to the conveyor that transports them to the reactor,
  • ii. the heat energy that is needed in the reactor can be generated centrally in one place and led to the reactor so that different heat energy amounts can be directed to the raw material particles that advance in different sectors in different phases,
  • iii. the charred and insulating skins of the raw material particles can be broken so that the heat energy can efficiently get their inside and thus speed them becoming pyrolisis product.

In this document the term “raw material” means all the solid particles in the process, also those that have become partly or totally pyrolysis products.

The invention will be described more closely in the enclosed drawings, where

FIGS. 1 and 2 a-2c present a feeding apparatus according to the invention,

FIGS. 3 and 4 present a heating system according to the invention in 3D seen directly from side,

FIGS. 5 and 6 present cuts B-B and C-C drawn in FIG. 4 where there can be seen the operating principle of the heating system,

FIG. 7 presents in FIG. 4 marked cut D-D where there can be seen the positioned mixing apparatuses and conveyor,

FIG. 8a presents the before mentioned apparatus in 3D,

FIG. 8b presents the before mentioned apparatus directly from above.

Next the construction and operation of a favorable solution will be presented referring to the before mentioned figures.

The continuously operating pyrolysis equipment according to the invention consists at least of a feeding apparatus 100, a reactor 200, a heating system 300, a mixing apparatus and conveyor 400, and channels to remove solid, liquid, and gas pyrolysis products from the reactor.

In the FIG. 1 there has been presented one feeding apparatus 100 according to the invention seen from behind and in the FIG. 2a from the level A-A cut in the FIG. 1. It consists of an essentially vertical feeding channel 1 to receive raw material 2 into the feeding apparatus 100 and diagonally positioned transfer channel 3 to transfer the raw material into the reactor. The down parts of the feeding and the transfer channels have been joined together and in this way obtained construction down part there has been adapted in a manner known per se liquid seal 10 to maintain oxygen-free condition in the gas tight transfer channel and the reactor when feeding the raw material 2 into the process. The liquid seal 10 has been adapted to be the lowest part of the feeding apparatus 100 and it has been filled with liquid 4 so that the liquid surface 5 reaches the feeding channel 1 and the transfer channel 3 and above the lower edge 6.1 of the partition wall 6 that separates the feeding channel and the transfer channel. The wall 10.1 of the liquid seal is naturally so called water tight. In this solution according to the invention a push button 7 has been adapted to the feeding channel 1 to press the lighter than the liquid 4 raw material particles under the surface 5 of the liquid and the first conveyor 8 has been adapted to the transfer channel 3 so that its down part 8.1 has an essentially parallel with the liquid seal bottom 10.2 and near it situated part and from where the mentioned conveyor has been adapted to lead near the diagonal down wall 3.1 to the upper part of the mentioned channel and its upper end 8.2 further above the feeding opening 201 of the reactor. Another conveyor 9 has been adapted to the feeding apparatus so that its down end 9.1 is below the partition wall 6 and its upper end 9.2 is above the liquid surface 5. The parts of the mentioned conveyors in the transfer channel are essentially parallel, the distance a between them is certain and the operation direction Z of both of them is diagonally upwards from the liquid seal. In this example, the first and the second conveyors 8, 9 are essentially of the same width as the feeding and the transfer channels, so called conveyor belts and they are driven by in the upper end adapted motors that rotate the first cylinders 8.3, 9.3 (not shown in the figures). The second cylinders 8.4, 9.4 have been adapted to the down ends of the conveyors and the first and the second belts 8.5, 9.5 are adapted to go round the first and the second cylinders to transport the raw material 2 upwards. In this example of the invention the motors that rotate the cylinders are hydraulic motors and the liquid 4 is oil.

The push button 7 consists of the frame 7.1 and the guides 7.2 attached to it, by the guides essentially vertically to move adapted tabular push organ 7.3 and power transfer organ 7.4 that has been fixed to the frame and the push organ to transfer the transfer power from the motor to the push organ. In this example of the invention the power transfer organ is a hydraulic cylinder.

The FIGS. 2b and 2c present in addition to the FIG. 2a the push button operation principle and the feeding apparatus 100 according to the invention operates so that the heavier than the liquid particles 2.1 of the raw material 2 that has been fed to the feeding channel 1 sink to the first conveyor 8 the belt 8.5 of which transports them to the feeding opening 201 of the reactor. The lighter than the liquid 4 particles 2.2 of the raw material remain on the surface of the liquid 4. The push organ 7.3 has been adapted to turn in relation to the joint 7.5 essentially from the vertical position to the horizontal position as it is pushed downwards by the power transfer organ 7.4 and it has been adapted to press essentially parallel to the liquid surface the raw material particles 2.2 under the liquid surface 5. By the conveyors 8, 9 caused slow flow of the surface of the liquid 4 into the direction of the transfer channel 3 move lighter than the liquid particles 2.2 from under the push organ 7.3 under the other conveyor 9 where they rise against its belt 9.5 and with the help of the belt and the projections 9.6 in it further to the surface of the liquid in the side of the transfer channel 3. In the transfer channel 3 the particles 2.2 at the surface of the liquid attach to the belt 8.5 of the first conveyor 8 and the raw material particles 2.1 on it and move to the feeding opening 201 of the reactor, from where they fall into the reactor 200. The push organ 7.3 has been adapted to move to and fro so that it turns around the joint 7.5 back to the vertical position in the beginning of the upwards return movement and again into the horizontal position in the beginning of the following downwards movement so that the raw material 2 that is fed to the feeding channel 1 has space to flow past it in the feeding channel. Because of the arrangement according to the invention the raw material 2 need not be preliminary treated to get it from the surface of the liquid 4 to the reactor and at the same time to maintain the oxygen-free condition in the reactor the whole duration of the continuous pyrolisis process.

Because there is a high temperature at the feeding opening 201 of the reactor certain parts of the first conveyor 8 require heat resistance capabilities. In this example the belt 8.5 is made of metal lamellas. The belt 9.5 of the second conveyor 9 has been made in the same way because this construction makes it possible for the extra liquid that has come from the liquid seal to the belt 8.5 and the raw material 2 to flow between the lamella gaps to the transfer channel 3 before falling the raw material 2 into the reactor 200.

In the FIG. 3 there has been presented in addition to the before described feeding apparatus of the pyrolisis equipment according to the invention the heating system 300 according to the invention in 3D, in the FIG. 4 directly from side, in the FIG. 5 from the cut B-B of the FIG. 4, and in the FIG. 6 cut C-C, Around the cylindrical essentially horizontal casing 202 of the reactor 200 there has been adapted a gas space 303 limited by another essentially reactor long casing 301 and the end walls 302 that has the shape of a cylinder for hot gases and the invention idea of this solution is directed to that the mentioned gas space has been divided in the lengthwise direction of the casings 202, 301 with the partition walls 304 in numerous heating sections. In this example of the invention there are seven heating sections and their reference numbers are 305a-305g. Furthermore the invention idea is that there is a distribution channel 306 adapted beside the presented construction from where a connection channel 307a-307g has been made into each heating section 305a-305g and the areas Aa-Ag of the connection channels are different with each other so that the end of the side of the feeding opening 201, that is the first end 203 leading to the heating section 305a cross section area Aa of the connect channel 307a is biggest, beside it situated connect channel 307b leading to the neighboring heating section 305b is next biggest and so on so that the connect channel 307g leading to the heating section 305g of the other end 204 of the reactor is smallest, its neighboring second smallest and so on. The hot gas channel 309 has been connected to the distribution channel 306 coming from the boiler 308. In this solution example of the invention the combustible that is burned in the boiler is pyrolysis gas that is created in the pyrolysis process and/or light fuel oil and the hot gas 310 led to the heating sections is flue gas or heated air heated by it in the heat exchanger. The favorable temperature of the hot gases that are led into the heating sections is max 7502C. The gases that have heated the reactor casing 202 are led out from the heating sections 305a-305g through the exit channels 311a-311g that are situated in the opposite side of the reactor than the connect channel. In order to secure a free circulation for gases the mentioned gas channels can be dimensioned with the same principle as the connect channels 307a-307g.

The heating system 300 according to the invention operates so that the hot gas generated in the boiler 308, heat exchanger, or other heat generator is led along the hot gas channel 309 into the distribution channel 306 from where it is distributed in relation of the cross-sectional areas Aa-Ag of the connect channels 307a-307g into the heating sections 305a-305g so that the amount of the heat energy heating the casing 202 of the reactor is greatest in the heating section 305a located mentioned casing part and smallest in the heating section 305g located mentioned casing part. The heat energy is transferred in the known way in the before described situation in the reactor casing 202 by conducting through it and then radiating into the raw material particles. The raw material particles in the beginning of the pyrolysis process need to maintain the optimal efficiency most heat energy in the beginning of the process and the least at the end. With the help of the invention, an optimal pyrolysis temperature can be achieved in each phase of the process.

In FIG. 5 there has been outlined a close organ 312 adapted into each connect channel 307a-307g that make it possible to reduce the flow areas of the connect channels smaller than their actual areas Aa-Ag. In this way, the distribution of the heat energy between the heating sections 305a-305g can be optimized even during the process.

It is possible to add to the pyrolysis equipment according to the invention in addition to the feeding apparatus 100 or the feeding apparatus and the heating system 300 an additional mixing apparatus and a conveyor 400. In the FIG. 7 that is a cut D-D of the FIG. 4 there has been presented the placing of the mentioned apparatus in the reactor 200 and in the figure Sa the actual apparatus in 3D. The mixing apparatus and the conveyor include a centre arbor 401 that has been adapted to rotate in relation to its center line CL that has been adapted same centered with the round casing 202 of the reactor and to go through the first end 203 of the reactor and reaches the second end 204 where there is an indentation it is supported to. The mentioned lead-in has been made gas tight. There have been fixed bar like blades 402 to the centre arbor 401 longwise and radial and the ends 403 of each of them have been shaped troughed. In the figure Sb there has been shown that in this example of the invention there are mentioned blades in four rows with the distribution of 902 so that there is an equal transition T between two neighboring blade rows arbor lengthwise, A power transmission unit has been connected to the centre arbor 401 to bring about the rotation movement R. The lengths L of the blades have been adapted so that their ends 403 are at the rubbing distance or a short distance from the reactor casing 202.

The mixing apparatus and the conveyor 400 according to the invention operate so that while the axle 401 is rotating the ends 403 of the blades advance near the reactor casing concave sides first and lift the raw material particles from the bottom of the reactor upwards supported by the casing 202. When the blade 402 passes the horizontal level H the support of the casing starts to reduce and when the blade has risen to a certain angle α over the horizontal level the ends 403 of the blades lose their grip to the raw material particles when they glide off them and hit against the casing at the bottom of the reactor. The mentioned particles break because of repetitive hits and thus the heat energy gets without hindrance inside the particles as their charred skins get broken. The invention operation of the blades 402 thus lifts the raw material particles up from the bottom of the reactor bottom and drops them back there. As the reactor 200 has been positioned horizontal the raw material 2 advances in the reactor 200 as follows: the failing raw material lot is distributed in relation to the blade 402 that lifts it on average so that half of it comes in the front side and half in the back side (in the direction of the advance of the raw material) so that the raw material advances in a favorable speed into the direction of the process advance.

Other Realization Alternatives of the Invention:

The feeding apparatus 100 liquid 4 can be pyrolysis oil that has been produced in the pyrolysis equipment according to the invention or other synthetic oil or some other for the situation suitable liquid.

The power transfer organ 7.4 of the push button operation principle can also be based on something else than hydraulics. All the ways to move the push organ 7.3 in the invention way realize the invention. As examples, chains and belts and motors to drive them can be mentioned.

The operation of the push button joint 7.5 and the turning of the push organ 7.3 regulating mechanism can be made in any favorable way. It is central in their operation that the push organ does not prevent or hinder feeding the raw material 2 into the liquid 4 during the operation.

The rotation power of the first cylinders 8.3 and 9.3 moving the belts 8.5 and 9.5 can also be created with some other than the before mentioned hydraulic motor. As an example an electric motor can be mentioned and a gear between it and the cylinder. It is also according the invention to set alternatively other cylinders 8.4 and 9.4 as drive cylinders.

The movement path of the first belt 8.5 can be supported in any known way in the down corner where its direction changes. As an example it can be mentioned glide guides adapted to the edges of the belt.

It is possible to adapt any favorable amount of heating sections 305a-305x to the equipment according to the invention and their widths Da-Dx can be made equal or different. In the before explained invention example they are equal.

The cross-sectional area sizes of the exhaust channels 311a-311x of the heating system 300 according to the invention have not as such been bound to the sizes of the cross-sectional areas Aa-Ax of the connect channels 307a-307x, they can also be larger than the last mentioned.

The heating system 300 according to the invention can also be realized so that there is not a separate distribution channel 306 but a part of the hot gas channel 309 operates as the mentioned distribution channel.

The close organ 312 can be realized in many different known ways. It is central that they can be used to reduce the flow areas of the gases going through the connect channels by regulating them either before starting the process or during it. The heating system according to the invention can also be realized in such a way that the connect channels have same size cross-sectional areas and the different flow amounts through them are achieved regulating the close organs.

The tightness of the lead-in of the axle 401 of the mixing apparatus and the conveyor 400 can be realized in the equipment according to the invention in many different ways. One functional solution is to tighten the lead-in by feeding pressurized nitrogen gas to it.

The most favorable installation manner of the axle 401 is to perform it with one lead-in but also the lead-ins at both ends of the reactor realize the invention.

The rotation power of the axle 401 can be generated and transferred to the axle in any known way. As an example an electric motor and between it and the axle adapted gear can be mentioned.

It can be seen the most favorable application from the point of view of the invention that the transition T of the blades 402 in the direction of the centre arbor is equal but also from this differing transitions are included in the scope of the invention. The width of the blades can vary within the limits that realize the invention idea of this pyrolysis equipment.

The tightening of the outlet opening of the solid pyrolysis product can be realized for instance using the product carbon statue. In this case, the solid product exiting from the reactor 200 through the opening forms at the moment of exiting a gas tight stopper in the opening.

It should be noticed that even though this explanation sticks to one for the invention favorable solution example this does not in any way want to limit the use of the invention only in this type of example usage but many variations are possible in the scope of the invention idea defined in the claims.

Claims

1. Continuously operating pyrolysis equipment that consists at least of: a. the feeding apparatus to feed the raw material into the reactor,b. the reactor to produce the pyrolysis products,c. the heating system to generate the heat energy that the pyrolysis process needs and to transfer it to the raw material,d. the mixing apparatus and the conveyor to mix and to transport the raw material particles there, ande. the channels to exit the solid, liquid, and gas pyrolysis products from the reactor, and which feeding apparatus includes the liquid seal essentially to maintain an oxygen-free condition in the reactor wherein the mentioned feeding apparatus includes at least:f. push button to press the lighter than the liquid of the liquid seal raw material particles from the feeding channel of the feeding apparatus under the liquid surface of the liquid seal,g. another conveyor leading from the liquid above the liquid surface to transport and to lift the lighter than the liquid raw material particles to the surface of the liquid in the transport channel,h. the first conveyor leading from the liquid to the feeding opening of the reactor to lift the heavier than the liquid raw material particles from the liquid into the feeding channel and to transport them and to the surface of the liquid gotten raw material particles to the feeding opening of the reactor.

2. The pyrolysis equipment according to the claim 1 wherein the gas space limited by the reactor casing, other casing, and the end walls for the hot gases has been divided into heating sections in the lengthwise direction of the reactor using partition walls that are a certain favorable amount and the connect channels leading into them from the distribution channel or from the hot gas channel have been adapted by their cross sectional areas different size so that largest of them is located in the reactor feeding opening/first end side connect channel and that their sizes are smaller than the previous when moving towards the other end of the reactor so that it is possible to lead different amounts of hat gas and heat energy at the same time into mentioned heating sections.

3. The pyrolysis equipment according to the claim 1 wherein the mixing apparatus and the conveyor consist of the centre arbor that has been adapted with at least one lead-in into the cylindrical reactor same centered with the reactor casing adapted to rotate in its centre line and the blades fixed to the mentioned axle both lengthwise and radial with a certain transition that have been adapted to lift raw material from the down part of the reactor supported by its casing and to drop it back to the down part of the reactor.

4. The pyrolysis equipment according to claim 1 wherein the raw material that is treated in it is rubber and/or plastic including polyolefin rich plastic waste.

5. The pyrolysis equipment according to claim 1 wherein that the push button consists of the frame, guides fixed to it, a plate push organ that has been adapted to move essentially vertically and the power transfer organ fixed to the frame and the push organ to transfer the transfer power from the apparatus that generates power to the mentioned push organ.

6. The pyrolysis equipment according to the claim 5 wherein the push organ has been adapted to turn in relation to the joint essentially from a vertical position essentially to a horizontal position when it is moved with the power transfer organ downwards and back to mentioned vertical position when it is moved upwards something that makes it possible for the raw material fed into the income channel to flow into the liquid.

7. The pyrolysis equipment according to claim 1 wherein the first and the second conveyors are conveyor belts.

8. The pyrolysis equipment according to claim 1 wherein the widths of all the heating sections are equal sized.

9. The method to perform continuous pyrolysis process wherein the pyrolysis equipment defined in claim 1 is used in it in the following way: a. the heavier and the lighter than the liquid particles of the raw material are transported through the liquid seal of the feeding apparatus with the help of the push button and the first and the second conveyors from the feeding channel to the transfer channel and further into the reactor through the feeding opening,b. the raw material particles that advance in the reactor in the pyrolysis process are heated by with each other different size hot gas amounts led into the heat system heating sections in order to direct different size heat energy amounts to the raw material particles in the locations of each mentioned section,c. the raw material is moved in the reactor in the direction of the process advance with the help of the blades rotating the circle and that have been fixed to the centre arbor of the mixing apparatus and the conveyor and at the same time the raw material is lifted with the ends of the mentioned blades using the support of the reactor casing above the line the horizontal level that goes through the centre arbor centre line from where they fall by gravity to the bottom of the reactor and thus caused hits are used to break the raw material particles to direct the heat energy inside them.

10. The method according to the claim 9 wherein the hot gas amounts that are led into the heating sections are made different from each other by different cross sectional connect channels and/or by close organs adapted in the mentioned channels.

11. The method according to the claim 9 wherein a product carbon statue is formed in the exit channel of the solid pyrolysis product to tighten the mentioned opening gas tight.

12. The method according to claim 9 wherein a part of the hot gas channel is adapted to function as the distribution channel.

13. The method according to claim 9 wherein the hot gas is flue gas produced in the boiler or heated air heated in a heat exchanger.

14. The method according to claim 9 wherein the temperature of the hot gases led into the heating sections is adapted to max value of 750° C.