SI9620118A - Method for hydrothermal hardening and drying of csh bonded moulded bodies and device for carrying out the method - Google Patents

Abstract

The invention relates to a method and a device for hardening and drying of calcium silicate hydrate-bonded moulded bodies in the form of an autoclave (1). At least one longitudinally extending live steam rail (10) and longitudinally-extending, laterally-spaced support members (3a, 3b, 3b) for the bearing elements receiving moulded body blocks (2a, 2b, 2c) to be hardened and to be dried are arranged inside the autoclave at the bottom. Heat sources (8a, 8d) are optionally provided in the region of the side autoclave walls, the size of the lateral distance of the bearing elements and the moulded body blocks (2a, 2b, 2c) is selected so that for steam circulation a flow duct (2d) is provided between the moulded body blocks (2a, 2b, 2c), and at least one upper steam rail (7a, 7b) is arranged for steam circulation above the flow duct (2d).

Description

YTONG AKTIENGESELLSCHAFT

Hornstrasse 3

D-80797 Munich

Germany

PROCEDURE FOR HYDER THERMAL TREATMENT AND DRYING OF SHAPED BODIES ASSOCIATED WITH CSH, ALSO A DEVICE FOR PERFORMING THE PROCEDURE

The invention concerns a process according to the parent term of claim 19 as well as a device according to the parent term of claim 1.

Calcium silicate hydrate (CSH) building materials, such as products made of porous concrete and lime sand, generally solidify in an autoclave at 10 to 16 bar overpressure, corresponding to 184 to 204 ° C in a vapor atmosphere. For the formation of desirable CSH phases, essentially tobermorite, environmental conditions must exist for a certain period of time (of the order of 5 hours): ca. 190 ° C in the presence of water.

As a rule, after filling the pressure vessel (autoclave) with the workpieces, it is raised "regulated by the supply of water vapor via a steam rail (in German: Dampfschiene), to a pressure of ca. 12 bar overpressure. Prior to this lifting phase, the flushing phase is also carried out. evacuations. Immediately after this lift phase, this pressure is now constantly maintained over a period of time (eg 5 hours) under saturated steam conditions. After this holding phase, the pressure is again regulated to the starting conditions.

The heating of the material to the desired temperature (eg 190 ° C) is carried out in the lifting phase by condensation of water vapor on the surface of the material. The retention phase serves to form phases (tobermorite) and thereby solidify the material.

After autoclaving, the CSH elements leave the autoclave s

-2 moisture content of the order of 30 to 40% (with respect to dry weight). This high moisture content is based e.g. primarily on high water content when casting raw materials of building materials. This adversely affects the transport and processing weight and the building-physical properties (eg thermal insulation) of the material during the first years (until natural desiccation) of the buildings thus constructed.

The method according to the type of claim 1 is known from US-PS 2 534 303. This process permits simultaneous or sequential curing and drying of CSH materials. By installing an additional source of heat (eg by steam or heating oil of the heated surface of the heat exchangers) in the autoclave, additional thermal energy is added to the CSH material, which causes evaporation, e.g. by casting water into the material and thereby drying the material. The known process can be performed in two variants.

In the first variant, it is dried after the holding phase and before the discharge phase. Upon completion of the holding phase and thus after curing, an additional heat source is included in the autoclave. This causes the temperature inside the autoclave to rise, thereby overheating the steam in the autoclave. Due to the overheating of the steam (and also due to the temperature radiation), the water evaporates from the CSH material and the material dries starting from the surface towards the inside of the material. Evaporation of the water of the material leads to an increase in the pressure in the autoclave, which can be prevented by the controlled discharge of water vapor from the autoclave. Since, for safety reasons, autoclaves may only be operated at a certain pressure up to certain upper limit temperatures, the pressure inside the autoclave (from, for example, 12 bar overpressure to, eg, 10 bar overpressure) can be optionally reduced.

As the material dries only after the curing or drying process is completed.

retention phase, there is no risk of material destruction due to premature evaporation of water from the surface of the material.

-3 However, curing the material requires additional time and energy.

This known process is also described identically in publications DE 33 26 492 Al and EP 0 133 239 Bi.

In the second embodiment, it dries during the lifting and holding phases. The heat source inside the autoclave is already activated before reaching the containment phase. As soon as sufficient solidification has occurred on the surface of the material, due to the evaporation of water on the surface, it can simultaneously cure and dry from the outside inwards. This process is possible because, as a rule, much more water is present in the CSH greens than is necessary for the formation of phases and thus for solidification. This process is also described in a comparable manner in DE 33 26 492 Al, EP 0 133 239 BI and in DE 40 35 061 Al. Thus, the supply of fresh steam to a certain pressure (eg 6 bar) and immediately afterwards heating to the desired final pressure (eg 12 bar), e.g. with heat radiation as well as steam production inside an autoclave with exclusive heat supply in the presence of air are described in these publications. The type of steam production inside the autoclave (heat exchanger, induction heating surfaces, microwaves) is irrelevant.

Following these known procedures can save energy. Pressure buildup inside the autoclave is done by evaporating water from the greens. We can largely relinquish external steam supply.

By already introducing the drying process during the lifting and holding phases, Cas is also saved.

Due to premature evaporation of water from the surface of the material, there is a risk of insufficient phase formation on the surface.

The material on the surface does not harden sufficiently and thus be destroyed.

The aim of drying CSH construction materials is to ensure a uniform drying rate for all building elements. In the present technical procedures, this is certainly difficult because of the fact that not only one block but more than one block is inserted into the autoclave, as a rule, three blocks simultaneously side by side or side by side. In order to achieve a high filling rate and thus high efficiency in autoclaving, the spacing of blocks is deliberately kept very small. Therefore, when the surfaces of the heat exchanger are mounted on the walls of the autoclave, the heat exchanger fails to transport the heat to the middle block. Only the outer walls of the two outer blocks are heated. Both outer blocks dry, the middle block remains moist.

Drying in the middle of the autoclave is therefore technically possible only if the additional heat input can be brought as evenly as possible to the surface of the blocks. This can be done, for example, by the forced flow (convection) of superheated steam inside the autoclave. This at the same time results in an improved heat transfer between the drying medium and the material surface.

In addition, the water evaporated on the surface of the material must be drained to prevent saturation of the drying medium (eg superheated steam) and thereby interrupt the drying process at that location. This problem can also be solved by the convection of superheated steam in the autoclave.

Publications EP 0 583 755 BI and EP 0 624 651 BI describe procedures designed to allow the forced flow of superheated steam in an autoclave.

According to EP 0 538 755 BI, the installation of convection fireplaces located around the side surfaces of heat exchangers is intended to achieve an increased proportion of natural convection inside the autoclave.

In accordance with EP 0 624 561 BI, the movement of steam within the autoclave is achieved by pressure pulse pressure with superheated steam. Pressure pulsation means that at regular intervals the steam is blown out via the discharge control valve, which means that the pressure in the autoclave is reduced and then fresh steam is blown (overheated) into the autoclave again via the fresh steam rail (pressure rise). The production of superheated steam can also take place inside the autoclave with heat exchangers!

It is inconvenient for both processes that the flow of steam does not move or move. with only a very small proportion it moves between blocks. By analogy with Hagen-Poisseulle's law, the volume flux proportions are proportional to the Fourth Potency of the diameter of the flow channels. This means that under the current flow-technical conditions, the largest proportion of steam flow between the autoclave wall and the two outer blocks moves by far within the autoclave.

It is an object of the invention to provide a process and apparatus for optimizing the cure and drying effect.

The device of the invention and the process of the invention are preferably suitable for the hardening of porous concrete. The apparatus and process are also suitable for solidifying and drying arbitrary molded bodies (Formkorper) bound with calcium silicate hydrate.

The process of the invention is essentially based on drying processes as described in US Patent No. 2 524 303 and EP 0 624 561. However, the amounts of superheated steam required to pulse the pressure are no longer supplied by blowing and blowing, but by feeding them energy via heat exchangers in circular operation. The device according to the invention allows the flow paths in the autoclave to be improved so that convection can also be carried out in the intermediate spaces between the cakes of porous concrete.

On the basis of the drawing (fig.), The invention will be explained in the following as an example, with the sole image being a schematic front view of an open autoclave. Autoclave 1 contains three cakes or blocks 2a, 2b, 2c of porous concrete, placed side by side at a lateral space (2d spaces) and supported by three curing bases or trolleys 3a, 3b, 3c, which are supported coordinated mounting elements, such as rails (not shown), arranged at the bottom of the autoclave at a lateral distance and extending in a longitudinal direction. Substrates for curing or. carts are the supporting elements for molded bodies that need to harden. The fresh steam inlet (eg 12 bar overpressure, 191 ° C), as required for the hardening of porous concrete, proceeds as before with the bottom steam rail extending in the longitudinal direction 10. The steam rail is a pipe with steam outlets for steam . It may also contain autoclave registers of heat exchangers 8a, 8d for the production of superheated steam and therefore for the drying of porous concrete arranged laterally on the walls of the autoclave.

According to the invention, above the porous concrete castors 2a, 2b, 2c, therewith, in accordance with the purpose, are arranged in the vicinity of the intermediate spaces 2d between the porous concrete cakes, two further upper steam rails 7a, 7b and preferably one or more additional steam rails 9 below the middle trolley for curing 3b or also in the vicinity of intermediate spaces 2d between the castors of porous concrete.

Both upper steam rails 7a, 7b are connected to the output of the circulation device 4, located outside the autoclave, and the lower steam rail 9 is connected to the input of the circulation device 4 (in German: Umwa1zer). The circulation device 4 can be designed either with a fan or with a steam jet nozzle.

According to one embodiment of the invention, the fresh steam rail 10 is adapted for extraction from the steam injected above. Through a three-way valve located outside the autoclave (and not drawn in the drawing), this rail 10 can be used once as a fresh steam rail and once as a suction rail.

The upper steam rails 7a, 7b, optionally also the steam rails 9, are preferably additionally combined with the heat exchanger registers 8a, 8b mounted on or adjacent to the rails. The tubes of the heat exchanger registers 8a and 8b may also be located inside the steam lines. The steam rails 7a, 7b, 9 act as a device for overheating the steam inside the autoclave.

Injectors to steam rails 7a, 7b, 9, 10 may contain injection nozzles and inlets for supplying fresh water. This allows the steam temperature to be precisely controlled. Cooling steam with water, for example, is reasonable if the temperature on the surface of the cakes of porous concrete is expected to leave the atmosphere of saturated steam earlier.

The injection of fresh water to cool the steam can be technically realized if sufficient flow rates prevail in the steam lines. Injecting fresh water into a non-moving steam regime (eg directly into an autoclave) is not technically possible for the first time or with great effort, and secondly does not result in the desired cooling of steam. According to the invention, this is achieved through a new method of steam circulation and circular operation.

The arrangement of the steam rails 7a, 7b and the arrangement and diameter of the non-represented holes (for steam outlet) are selected in the steam rails by flushing the bulk with the circulating device 4 of the injected steam into the intermediate spaces 2d between the piles of porous concrete. Only a small portion of the amount of steam should flow in the space between the outer surfaces of the muffins and along the wall of the autoclave.

According to a further specific embodiment of the invention, the middle cake of porous concrete 2b is raised higher than the two outer cakes. The height of this increase is preferred

-8 Approximately the same width as the spaces between the cakes, e.g. ca. 10 to 20 cm. This creates very favorable flow channels of uniform diameter between the cakes.

It is technically possible to realize the increase of the middle wheel in such a way that the commonly used middle pins of the hardening trolley (not shown), which hold the middle solidifying base 3b, are formed in a prolonged manner. It is also conceivable that the middle solidification base 3b is raised via a suitable lifting device mounted on the solidification trolley (not outlined) immediately before autoclaving.

To improve the transport of steam or drying medium and the passage of heat into the interior of the building element, transitional holes may be formed in the cake of porous concrete. Depending on the manufacturing process, these holes in the cake may be formed, for example, by making needles into the cake after the lifting phase (before Garphase) (before sawing).

This action results in a more even drying of the building element between the outer surfaces and the core of the porous concrete roll. At the same time, the surface of the material increases with the dry medium.

The insertion of these holes is especially advantageous if there is sufficient convection inside the autoclave and thus a sufficient pressure difference between the holes of the holes. Otherwise, the drying medium in the holes is saturated and the desired drying effect inside the building elements is not established.

By allowing the steam supplied by the circulation device 4 to the autoclave by steam rails, the steam is allowed to be transported specifically to the places where it is supposed to be effective, e.g. to the sides of the cake.

Flow direction and amount of steam exiting the steam

-9 rails 7a, 7b can be easily set up with suitable arrangements and different bore diameters. This eliminates the complicated installation of guide sheets and fireplaces. However, steam rails may be additionally fitted with guide plates (not inscribed).

Emerging convection causes a more even distribution of steam in the autoclave even without drying. The formation of temperature gradients between the upper and lower sides of the autoclave and the risk of uneven curing of porous concrete are thus reduced.

The arrangement of heat exchangers, for example, which can be heated by heating oil directly at or near the steam rails 7a, 7b, causes the steam in the autoclave to overheat. As a result, no losses occur in the lines outside the autoclave. The heat energy of the heat exchangers, which is not transferred to the steam rails 7a, 7b, causes the steam to overheat in the remaining autoclave space and thus not be lost.

Unfavorable geometric flow conditions, which have hitherto made the drying of porous concrete in the autoclave substantially more difficult, because the intermediate space between the curing bases 3a, 3b, 3c was too small, were prevented by raising the middle stake.

The holes in the cake result in an increased surface area of the kolaCa and thus improved heat transitions and improved material transport inside the mold. This results in a more even drying of the porous concrete cake.

According to the process of the invention, curing and drying can be carried out in analogy with the process known from US-PS 2 524 303

CSH construction materials in two different ways: For the first time after completion of the holding phase (after solidification of the material) and

10 alternatives between the lifting phase and the holding phase (simultaneous drying and curing).

After the material has been introduced into the autoclave - according to the state of the art - after a possible preliminary rinse and evacuation phase - the pressure in the autoclave is continuously increased to the value of ca. 12 bar overpressure.

In the next holding phase, this pressure and temperature in the autoclave is maintained until the solidification of the material is largely or completely complete (ca. 2 to 5 hours.)

We can now start the drying process by turning on the heat source in the autoclave and starting the bypass device.

During the heating process, the water evaporates from the CSH material and the pressure in the autoclave increases. In accordance with US-PS 2 524 303, this pressure can now be maintained at a constant level (12 bar overpressure) (temperature rise) (reduced temperature) or reduced (autoclave temperature constant) by means of controlled exhaust through the steam control valve. Upon completion of the drying phase with controlled steam blowing, the pressure inside the autoclave is reduced to ambient conditions via the steam control valve.

Alternatively, drying may also be carried out in accordance with the pulse operation described in EP 0 624 562 81. The pressure-lowering phase is effected by blowing the steam through a control valve for releasing steam and raising the pressure by evaporating water from the mass of porous concrete. The blown off steam can either be poured into another autoclave or driven into a steam collector and available for further autoclaving. With increasing drying rate of porous concrete cake, Cas is also extended to evaporate sufficient water from the cake to increase pressure. As a result, pulse widths become longer with increasing drying time.

-11When drying between the lifting and holding phases, after flushing and evacuation, the pressure in the autoclave is raised to a certain value (eg 5 bar overpressure) after the flushing and evacuation phase, which is still significantly below the required pressure level for normal autoclaving (eg 12 overpressure bar). Further pressure rise to the desired solidification pressure (12 bar overpressure) occurs after the heat source and the circulation system have been turned on by evaporating water from the surface of the material. Typically, during this step of the process, the temperature at the surface of the material is constantly monitored by means of a suitable temperature sensor during this pressure boosting phase. As soon as the surface temperature of the material exceeds the prescribed upper limit (saturated vapor temperature corresponding to the prevailing pressure in each case), by switching off the heat source and injecting water through the nozzles in the steam rails 7a, 7b, cooling the heated steam in the autoclave and thereby cooling the material surface .

This monitoring of the temperature and cooling of the material is reasonable in order to prevent the evaporation of too much water from the surface of the material before the required curing time (ca. 2 to 5 hours), thereby preventing the formation of CSH phases required for curing. happening and the material on the surface would be destroyed. Upon completion of this combined lifting and curing phase, the discharge phase may commence, or, depending on the desirable drying step, further drying, e.g. using the pulse method described above. The magnitude of the lower booster pressure depends primarily on the water content of the surface of the porous concrete cake and therefore on the introduced material of the greens and also on the degree of filling in the autoclave, the more water available on the surface of the material for evaporation, the smaller the value can be selected. This value can be determined either experimentally or by calculation (with knowledge of the drying curve of the material).

-12Because of the level and duration of heat supply inside the autoclave, the desired residual humidity of the material can then be set during solidification and drying. Setting the egg The residual humidity (depending on the duration of drying) depends on the material and can be determined either experimentally or by calculation (knowing the curve of the drying process). By varying the duration of energy delivery, we can now dry extremely economically (i.e., dry material at the same energy consumption as the previous saturated steam autoclaves), or we can regulate any desired drying rate.

the smaller the desired residual humidity of the material, the more water must evaporate from the material and the more steam is produced inside the autoclave. From a certain degree of drying, the amount of steam produced is greater than is necessary to raise the next autoclave to the initial pressure (eg 6 bar). This excess superheated and highly prestressed steam (12 bar overpressure) can be used, for example, to heat heat chambers and heat tunnels or to produce electricity (eg for an external circulation device) by means of a steam turbine.

According to the invention, therefore, at the same energy consumption as before, more dry material can be produced by the combined solidification and drying process. The desired residual humidity is adjustable with the duration of the drying process. The process of the invention is a process that contributes to a material for controlling surface temperature. It is possible to regulate the quality of the steam by overheating and cooling, thereby reducing the failure due to solidification.

According to the invention, a further variant of the drying process is possible. In this variant, it is only dried during the lifting phase. The process is as follows: After the flushing and vacuum phases are completed, the autoclave is raised to the prescribed pressure (eg 2 to 5 bar) with either fresh steam or steam from the reservoir or other autoclave. The water is then evaporated to reach the desired holding pressure (eg 12 to 16 bar) due to the activation of an additional heat source and the circulation of steam from the formed blocks. In order to save on the parts of the device, the side registers of the heat exchangers 8c, 8d may be canceled if necessary. The evaporation rate and temperature in the autoclave can then be set by regulating the heat source and the circulation device or by injecting fresh water. After reaching the holding pressure (12 to 16 bar), we disconnect the heat source and the circulation device or suppress them so that only the pressure and thermal losses of the autoclave are compensated. Further drying should not occur during the holding phase.

The advantages of this process are that existing autoclave devices can be retained. The temperature in the autoclave during the lifting phase does not exceed the saturated vapor pressure of the holding pressure. The construction of an autoclave for higher temperatures is thus unnecessary. Multiple autoclaves can be driven with only one heating oil device and one steam circulating device, since these devices are only required during a relatively short time interval (in the lifting phase) during the autoclaving process a. During drying during the holding phase (variant 1 or 2), additional steam is generated by evaporation of water from the molded bodies. This steam must be blown out during the holding phase. The necessary technical devices (exhaust control valves, steam rails for discharge) are also required when combining more than one autoclave only once.

The steam rails 7a, 7b, 9 may also be designed so that the steam outlet openings have the same and / or different diameters. They may also be equipped with e.g. interchangeable nozzles or nozzles which are e.g. they may be of varying lengths or so oriented or curved to achieve predetermined directions of flow.

According to a further embodiment of the invention, the side heat exchanger registers in 8c, 8d are formed and arranged such that the intermediate space between the surface of the heat exchanger registers and the outer surface of the two outer molded bodies 2a, 2c corresponds to approximately the distance between the molded bodies 2d. In this case, two further steam rails of types 7a, 7b may be installed above the intermediate spaces between the heat exchanger registers 8c, 8d and the outer molded bodies 2a, 2c.

Claims (34)

A device for solidifying and drying molded bodies bound with calcium silicate hydrate in the form of an autoclave (1), in which at least one steam rail (10) is arranged on the bottom side for fresh steam extending longitudinally and into longitudinal directions extending, at a lateral distance from each other, the supporting elements (3a, 3b, 3c) arranged for the mounting members holding the blocks of shaped bodies (2a, 2b, 2c), which must harden and dry and, if necessary, in the region of the side walls of the autoclave, the predicted heat sources (8a, 8d) characterized in that a) the lateral distance of the mounting elements and the shaped body blocks (2a, 2b, 2c) is chosen so large that a flow channel (2d) is defined between the shaped body blocks (2a, 2b, 2c), b) there is a steam circulation device by which the steam is flushed out substantially through the circulation duct (2d), c) At least one upper steam rail (7a, 7b) arranged above the flow channel (2d) for circulating steam. Apparatus according to claim 1, characterized in that at least one further steam rail (9) is arranged below the solidification bases (3a, 3b, 3c) in the flow channel area (2d). Apparatus according to claim 1 or 2, characterized in that the upper steam rail (7a, 7b) is connected to the outlet of the circulating device (7a, 7b) for the formation of the circulating steam operating device. 4) located outside the autoclave (1) and the lower steam rail (9) with the inlet of the circulation device (4). -164. Apparatus according to claim 3, characterized by tea, that the circulation device (4) is made by means of a fan. Device according to claim 3, characterized by tea, that the circulation device (4) is made with a steam jet nozzle. Device according to one or more of Claims 1 to 5, characterized in that the fresh steam rail (10) is adapted for extracting steam injected through the upper steam rail (7a, 7b). Apparatus according to claim 6, characterized by the fact that the fresh steam rail (10) is connected via a three-way valve outside the autoclave (1) to both the fresh steam supply and the suction device. Apparatus according to one or more of Claims 1 to 7, characterized in that the upper steam rail (7a, 7b) has a steam superheater and for this purpose is preferably combined with a register of heat exchangers (8a, 8b) which for example, it is mounted inside or near the steam rail (7a, 7b). Apparatus according to claim 8, characterized by tea, that the steam rail (9) also has a steam overheating device, for example at, inside or near the steam rail (9). Device according to one or more of Claims 1 to 9, characterized by the fact that inlets for steam intake rails (7a and / or 7b and / or 9 and / or 10) are arranged inlets and injection openings fresh water into the steam stream. Apparatus according to one or more of Claims 1 to 10, characterized in that the arrangement of the steam rail (7a, 7b) is itself and the arrangement and diameter of the steam outlet openings in the steam rail and preferably also their spatial position -17 in the form of, e.g. nozzles or fittings chosen so that most of the injected steam is flushed into the flow channel (2d), with only a small portion of the amount of steam flowing along the space between the outer surfaces of the molded body blocks (3a, 3c) and the autoclave wall. Apparatus according to one or more of Claims 1 to 11, characterized in that the curing base (3a or 3b or 3c) is arranged relative to the other curing base (3a or 3b or 3c). Apparatus according to claim 12, characterized by the fact that the elevation height approximately corresponds to the width of the flow channel (2d). Apparatus according to one or more of Claims 1 to 13, characterized in that the steam rails (7a, 7b, 9, 10) are provided with guide plates. Apparatus according to one or more of Claims 8 to 14, characterized in that the heat exchanger registers (8a, 8b) are designed in such a way that they can be heated with heating oil. Apparatus according to one or more of Claims 1 to 15, characterized in that the width of the flow channels is 5 to 20, in particular 10 to 20 cm. Device according to one or more of Claims 1 to 16, characterized in that the lateral heat exchanger registers (8c, 8d) are formed and arranged so that the space between the surface of the heat exchanger registers and the outer surface of the two external molded bodies ( 2a, 2c) corresponds to approximately the distance between the molded bodies (2d). 18. The device according to one or more of claims 1 to 17, -18 marked by the fact that two further steam rails of type (7a, 7b) are positioned above the intermediate spaces between the registers of the heat exchangers (8c, 8d) and the outer molded bodies (2a, 2c). 19. A process for solidifying and drying molded bodies bound with calcium silicate hydrate in an autoclave in an atmosphere of water vapor having a lifting phase, a holding phase and a discharge phase, whereby the molded bodies are dried, especially using a device according to one or more claims 1 to 16, characterized in that the molded bodies to be cured are arranged at a lateral distance from each other, thus forming an intermediate space (2d) and that a solidification vapor is flushed through the intermediate spaces and drying but only for drying. 20. The method according to claim 19, characterized in that a greater amount of steam is flushed into the intermediate spaces (2d) and a smaller amount of steam through the space between the blocks of molded bodies and the autoclave wall. 21. A method according to claim 19 and / or 20, characterized by a complexion, to use intermediate spaces between 5 and 20, especially between 10 and 20 cm. 22. A method according to one or more of claims 19 to 21, characterized in that one block of molded bodies is raised in height. A method according to one or more of Claims 19 to 22, characterized in that a steam rail is used to emit steam under the blocks of molded bodies. 24. A method according to one or more of claims 19 to 23, characterized by the complexion that circulating steam is used. A method according to one or more of claims 19 to 24, characterized in that it® is optionally used during steam circulation, e.g. alternately superheated steam and cooled steam. 26. The process according to claim 25, characterized by the te® that the cooled steam is produced by injecting water into the steam inlet. 27. A process according to one or more of claims 19 to 26, characterized by the use of the heat exchanger registers adapted for steam circulation used for steam circulation for the production of superheated steam. 28. The process according to claim 27, characterized by the te® that the registers of the heat exchangers are controlled by heating oil. 29. A method according to one or more of claims 19 to 28, characterized in that te® is carried out in pulse operation, whereby for the purpose of reducing the vapor pressure, the vapor is blown out and the vapor pressure is produced by evaporating water from the mass of molded bodies. 30. The method according to one or more of claims 19 to 29, characterized in that the temperature on the surface of the material is measured by a suitable temperature sensor and that overheating and / or overheating are carried out. steam cooling regulates the measured value accordingly. 31. The method according to one or more of claims 1 to 16, characterized in that te® is that the drying is carried out exclusively during the two phase and that only the solidification is carried out during the holding phase. A method according to claim 31, characterized by the te® that the steam circulating device (4) with heat exchanger registers (8a, 8b) is used only during the lifting phase. -2033. The process according to claim 31 or 32, characterized in that steam generated during the drying phase is used to generate pressure in the autoclave. A process according to one or more of claims 31 to 33, characterized by a tea, in order to carry out the drying until the holding phase is reached. A method according to one or more of claims 31 to 34, which has the characteristic features of one or more of claims 19 to 30.