Method for determining a setting time and / or an actual degree of hydration or for providing a target degree of hydration of a settable composition, and section of a production line for products comprising settable compositions

Abstract

The invention relates to a method for determining a setting time and / or an actual degree of hydration of an exothermically settable composition (4) (hereinafter referred to as settable composition (4)), in particular a gypsum composition, - wherein the settable composition (4) is being conveyed in a conveying direction (F) along a setting line (D) and - discrete surface temperatures (Tb,i) of the settable composition (4) are recorded at at least a plurality of points (i) along the setting line (D) and an ambient temperature (Tamb; Tamb,j), in particular above the settable composition (4), is recorded at at least one point (j), - wherein discrete corrected plate temperatures (Tcorr,i) are calculated using the discrete measured surface temperatures (Tb,i) and the at least one ambient temperature (Tamb, Tamb,j), and - a sigmoid function is adapted to the discrete corrected plate temperatures (Tcorr,i), which represents a time-related temperature curve Tcorr(t) or a distance-related temperature curve Tcorr(d), and - the setting time (tA) and / or the degree of hydration of the settable composition (4) is determined at at least one position (P) of the setting line (D) on the basis of characteristic parameters of the adapted sigmoid function. Furthermore, the invention relates to a method for providing a target degree of hydration of an exothermically settable composition at a predetermined position (P) of a setting line (D) of a production line using the determination method, and to a section of a production line for carrying out the methods.

Description

[0001] Description

[0002] METHOD FOR DETERMINING A SETTING TIME AND / OR AN ACTUAL DEGREE OF HYDRATION OR FOR PROVIDING A TARGET DEGREE OF HYDRATION OF A SETTABLE COMPOSITION, AND SECTION OF A PRODUCTION LINE FOR PRODUCTS COMPRISING SETTABLE COMPOSITIONS

[0003] The invention relates to a method for determining a setting time and / or an actual degree of hydration of an exothermically settable composition, as well as a method for providing a target degree of hydration of an exothermically settable composition and a section of a production line for products comprising settable compositions.

[0004] To determine a specific degree of hydration of an exothermically settable composition, it is known to determine the setting behavior of the exothermically settable composition by means of an AT-line measurement. In the course of such an AT-line measurement, a sample of the exothermically settable composition is observed in a thermally insulated container away from a production line with regard to its temperature curve during the setting. The temperature curve over time of the exothermic setting of the sample is recorded. The hydration curve thus determined is used to infer the corresponding degree of hydration of the settable composition on a production line. A turning point in the characteristic sigmoid curve of the temperature curve represents the so-called setting time tAof the exothermically settable composition. Using the temperature-time curve determined in this way and taking into account a known conveyor speed v of a conveyor on a production line, a certain degree of hydration is concluded at a certain position P along a setting line D.

[0005] This method of AT-line measurement is time-consuming and laborious to carry out. Furthermore, the hydration curves obtained in a laboratory environment cannot always be transferred with sufficient accuracy to the real environment of a production line for products made of an exothermically settable composition. Environmental influences along the production line are completely disregarded.

[0006] US 10, 677, 698 B2 describes an online measurement of the degree of hydration of a slurry of an exothermically settable composition. In this case, an indentation force for a predetermined indentation depth is measured at selected points along the production line, at least at one selected point on the production line, using an indenter, and the degree of hydration of the settable composition at the point of indentation is inferred from this, depending on the indentation depth. Although this solution provides an online measurement, it also causes unwanted indentations for the purpose of testing at the points to be tested, which may lead to an undesirable optical appearance in the end product.

[0007] US 2004 / 0052297 A1 discloses a thermal monitoring system including multiple infrared sensors. It performs real-time monitoring and alarming for any out of tolerance thermal conditions occurring during a manufacturing process. Although US 2004 / 0052297 A1 teaches the use of a compensation temperature derived from the ambient temperature there is no teaching of how to modify raw temperature data of the board to get information regarding a setting time and / or an actual degree of hydration. The object of the invention is therefore to provide a method for determining the setting time and / or the actual degree of hydration of an exothermically settable composition that is improved over the prior art, that works contactlessly, i.e. without mechanical contact with the settable composition, and that can also be realized as part of an in-line measurement. In addition, the method according to the invention is to take into account varying environmental influences, in particular varying ambient temperatures along the production line, so that the determined degree of hydration or the determined course of the setting can be determined independently of, in particular, external temperature conditions. As a result, the method according to the invention is to help reduce the personnel required to supervise a production line for products made from a settable composition.

[0008] A further task of the invention is to provide a target degree of hydration of the exothermically settable composition within a certain tolerance band, in particular with a higher accuracy than the state of the art, at a certain position P along a setting line D.

[0009] Furthermore, the invention is intended to provide a section of a production line for products made of exothermically settable compositions, with which the processes according to the invention can be carried out.

[0010] With regard to determining the setting time tAand / or the actual degree of hydration, the task according to the invention is solved by a method for determining a setting time tAand / or an actual degree of hydration of an exothermically settable composition (hereinafter referred to as settable composition), in particular a gypsum composition, wherein the settable composition is conveyed in a conveying direction F along a setting line D and discrete surface temperatures Tb,i of the settable composition and at least one ambient temperature Tamb,’ Tambj, in particular above the settable composition, are recorded at at least a plurality of points i along the setting line D, wherein discrete corrected plate temperatures TCOrr,i are calculated using the discrete, measured surface temperatures Tb and the at least one ambient temperature Tamb, Tambj, and a sigmoid function is adapted to the discrete corrected plate temperatures Tcorr,i, which represents a time- related temperature profile TCOrr(t) or a distance-related temperature curve TCOrr(d), and the setting time tAand / or the actual degree of hydration of the settable composition is determined at at least one position P of the setting distance D on the basis of characteristic parameters of the adapted sigmoid function.

[0011] The above-mentioned method makes it possible to provide a non-contact online determination method for an actual degree of hydration and / or a setting time, taking into account the current ambient conditions in a production line, in particular ambient temperatures. Due to the non-contact measurement, no traces resulting from a measurement can be recognized on the finished product. In particular, the consideration of ambient temperatures allows for the consideration of diurnal and / or seasonal ambient influences, so that the determination of the setting time as well as the determination of the degree of hydration at a certain position P can be carried out with higher accuracy.

[0012] In a particular embodiment of the method, a time coordinate twor a distance coordinate dwof a turning point W of the sigmoid function is defined as setting time tAor as setting distance dA. This measure makes the results obtained using the method according to the invention particularly comparable with previously measured values and empirical values from comparable AT-line methods or other measuring methods from the state of the art that use the same definition for the setting time tA.

[0013] These advantages can also be achieved if a time coordinate twor a distance coordinate dwof a point with maximum slope of the sigmoid function is defined as setting time tAor setting distance dA.

[0014] It is advantageous to define a ratio of a temperature increase AT(t) at a point in time t to a total temperature increase ATCOrr,ges or a ratio of a temperature increase ATcorr(d) at the position P to a total temperature increase ATCOrr,ges as the actual degree of hydration.

[0015] This measure also increases the comparability of the results obtained according to the invention with measurement results from already known measurement methods.

[0016] To reduce the complexity of the underlying calculations for determining the influences of the environmental influences, in particular the ambient temperatures, it is expedient that, for the calculation of the corrected plate temperature TCOrr,i, at least one, preferably all of the following assumptions are made for the sake of simplification:

[0017] - there is no heat transfer from the interior of the settable composition to an environment U on the underside or to an environment U on the sides of the settable composition,

[0018] - ideal heat transfer occurs within the settable composition;

[0019] - a temperature curve TCOrr(t) is constant between two points i;

[0020] - a heat transfer coefficient k between the settable composition and the environment U does not depend on the ambient air temperature or ambient air humidity.

[0021] In order to achieve a meaningful and significant approximation of a swan-neck curve, an S-curve or a so-called sigmoid function, it is useful to measure the surface temperature Twand, independently of this, the ambient temperature Tamb,j at at least 4 points, i.e. i, j is greater than or equal to 4, preferably at 9 points (i,j =9), the surface temperature Tb,i and, independently of this, the ambient temperature Tamb,j are measured, with the proviso that j < i.

[0022] The greater the number of i,j, the higher the measurement accuracy along the setting distance D. However, the higher the number of points i,j, i.e. the measuring points, the higher the costs for the measuring equipment and the computing costs for evaluating the measuring results. The skilled person will be able to determine an economically and technically reasonable number i,j depending on the intended use. It should also be taken into account that in the simplest case, the ambient temperature Tamb,j is measured at only one point (j=1 ) of the setting distance D. This can be particularly useful if, due to the existing production conditions in the corresponding production hall, it can be assumed that the ambient temperatures along the setting line D are almost the same.

[0023] According to a useful calculation formula, the corrected plate temperature TCOrr,i is calculated as follows: wherein

[0024] - i is a location at which the surface temperature Tb is measured,

[0025] - j is a location at which the ambient temperature Tambj is measured,

[0026] - m is a running variable that represents an m-th location i,

[0027] - m(j) is a location j that is located closest to an m-th location i and that is assigned to the m-th location i,

[0028] - Tcorr is the corrected plate temperature at location i

[0029] - Tb is the measured surface temperature Tb at location i

[0030] - Tb,m is the measured surface temperature at location m

[0031] - Tamb.mQ) is the ambient temperature Tamb,j measured at a point j closest to the m-th point i, which is assigned to the m-th point i

[0032] - Atmis a time period which a certain volume of the settable composition requires from an (m- 1 )-th point i to a subsequent m-th point i along the conveying direction F

[0033] - K is an experimentally determined correction factor having the dimension [1 / s],

[0034] With the alternative embodiments listed below, it is possible to adapt the method according to the invention to different environmental constellations and accuracy requirements. For example, it can be provided that the number of points j>1, in particular the number of points j is equal to the number of points i, i.e. that the ambient temperature Tambj is measured at all points i, or alternatively that the number of points j is smaller than the number of points i, i.e. that the ambient temperature Tambj is measured at fewer points j than there are points i.

[0035] In the event that the ambient temperature Tambj is measured at fewer points j than the surface temperature Tb at points i, for the corrected surface temperature Tcorr the measured surface temperature Tb,mof the m-th point i is correlated with the measured value of the ambient temperature Tamb,mQ) whose location j is located closest to the m-th location i. That is, Tamb,m(j) corresponds to the measured value Tamb,j that is located closest to the m-th location i.

[0036] In particular, for improved repeatability of the method according to the invention and for improved reproducibility of the results obtained thereby, it may be useful for the correction factor K for a settable composition to be determined experimentally in the course of AT-line measurements.

[0037] A correction factor K determined for a specific example of use has, for example, the value K = 1 .5 - 2.5 10-31 / s depending on a plate thickness of 0,010 m to 0,018 m.

[0038] It is expedient to determine the correction factor K for a settable composition experimentally according to the formula

[0039] K=— - (—) °- p*c h Vo7 8

[0040] Wherein k is a heat transfer coefficient in [W / m2K] of the settable composition to the environment U, p is a density in [kg / m3] of the settable composition and c is a specific heat capacity [J / kgK] of the settable composition h in [m] is a thickness of the settable composition (4), / v\0,8

[0041] ( -) is an optional correction factor which, for further simplification, can also be assumed to have the value 1 , taking into account an instantaneous belt speed v and a reference belt speed v0.

[0042] It is also expedient for the temperature measurement of the surface temperatures Tb,i to be carried out in a non-contact manner, for example using infrared thermometers.

[0043] This ensures, in particular, that the temperature of the product is measured in a nondestructive and, in particular, non-damaging manner.

[0044] The method according to the invention can advantageously be applied to exothermically settable compositions, e.g. one or more of the following settable compositions:

[0045] - cement compositions, e.g. Portland cements, Sorel cements

[0046] - gypsum compositions.

[0047] With regard to the task of providing a target degree of hydration, the task according to the invention is solved by a method for providing a target degree of hydration of an exothermically settable composition at a predetermined position P of a setting section of a production line, wherein the actual degree of hydration at the position P is determined by means of the method according to any one of claims 1 to 12 and wherein, if the actual degree of hydration at position P differs from the desired degree of hydration at position P by more than a hydration tolerance at position P, the mass composition of the settable composition in an application device, in particular a mixer on the production line, is adjusted until the actual degree of hydration at position P is within the hydration tolerance at position P.

[0048] This method makes it possible, in particular, to provide an online process control for the production of products from an exothermically settable composition in a simple manner using the results of the method according to the invention for determining an actual degree of hydration. This is particularly important for determining the degree of hydration before a cutting device, since a settable composition must already have a certain minimum degree of setting before it can be cut without any quality problems.

[0049] It is useful to adjust the composition of the composition by increasing or reducing the proportion of a setting accelerator.

[0050] The device-specific tasks of the invention are solved with a section of a production line for products comprising settable compositions, in particular a setting line D of a production line for plate-shaped gypsum products, wherein the section extends between an applicator for a slurry of the settable composition and a cutting device for separating an at least partially settable composition, and the settable composition can be conveyed along the setting line D by means of a conveying device along the conveying direction F, wherein at least one temperature detection device is arranged at at least a plurality of locations i along the setting line D, which devices are set up and designed to measure at least the surface temperature Tb,i of the settable composition at the point i, and in particular along the setting line D there is at least at one or more points j a temperature detection device which is set up and designed to measure an ambient temperature Tamb,’ Tamb,j of an environment U of the settable composition.

[0051] With such a design of a section of a production line, the methods according to the invention can be carried out in a simple and practical manner. Such a section of a production line according to the invention is simple in design and robust in handling.

[0052] To meet certain requirements in terms of accuracy and / or cost-effectiveness, it may be expedient for the number of positions i to be at least 4, in particular 9, and for the number of positions j to be at least 1 , with the number of positions (i) in particular being equal to the number of positions (j).

[0053] For the purpose of forming a production line for the manufacture of plate-shaped gypsum products, it is expedient for the application device to be a mixer of a production line for gypsum products and for the cutting device to be a cutting device for plate-shaped gypsum products.

[0054] In order to reduce the space required and to reduce the complexity of the construction of a production line according to the invention, it is useful for the temperature detection devices to be designed and set up in such a way that they can measure both the surface temperature Tb of the at least partially set settable composition and the ambient temperature Tamb,j at any point i.

[0055] In order to increase or decrease the accuracy of observation and / or the accuracy of the course of certain sections of the binding section, the temperature detection devices are advantageously arranged uniformly distributed along the binding section D or they are arranged along a section of the binding section D in the conveying direction F at a closer distance to each other or further apart from each other compared to the remaining binding section D.

[0056] For carrying out the method according to the invention, it is particularly useful to have means for detecting a conveying speed v of the at least partially set settable composition.

[0057] The following drawing is used to explain the invention in more detail by way of example. It displays:

[0058] Figure 1 : an overview of a production line for plate-shaped gypsum products in accordance with the invention;

[0059] Figure 2: a schematic side view of a setting line D of a section of the production line in accordance with the invention;

[0060] Figure 3a: a diagram showing surface temperature gradients along a setting line D without taking into account ambient temperature influences;

[0061] Figure 3b: a diagram showing surface temperature curves along a setting line D, taking into account ambient temperature influences;

[0062] Figure 4: a flow chart illustrating the method according to the invention for determining a setting time and / or an actual degree of hydration;

[0063] Figure 5: a flow chart illustrating the method according to the invention for providing a target degree of hydration at a position P of the setting line D.

[0064] Figure 6: an example of the course of a sigmoid function obtained from 9 temperature measurement values T. Figure 1 shows an example of a production line 1 for manufacturing a product from an exothermically settable composition 4, using the example of a production line 1 for gypsum plasterboards 2, which are board-shaped gypsum products 2. An application device 3 provides a composition of the settable composition 4 and applies it to a first cardboard layer 5. Immediately after the application device 3, which is designed, for example, as a mixer, the settable composition 4 is present as a slurry with a very low degree of hydration, for example less than 4%. A section between the mixer / application device 3 and the cutting device 6, which is located downstream of the application device 3 in a conveying direction F, is defined in the example shown as a setting section D. A turning station 7 and a dryer 8 are provided downstream of the cutting device 6 in the conveying direction F. A packaging station, for example a pal letizer 9, is provided at the end of the production line 1 . A conveyor 11 (see Figure 2) is provided, by means of which at least the settable composition 4 is conveyed from the application device 3 along the setting line D in the conveying direction F.

[0065] A plurality of temperature detection devices 10, in particular i=4 or more than 4, and in particular i = 9, are provided along the setting line D. The temperature detection devices 10 are set up and designed in such a way that they can detect a surface temperature Tb of the settable composition 4 itself or of a product / intermediate product produced along the settable line D and comprising the settable composition 4, without contact. The surface temperature Tb is measured at at least 4 points i, in particular at more than 4 points i, and in particular at 9 points i. Infrared thermometers, for example, can be used as suitable temperature detection devices 10. At least one of the temperature detection devices 10 is set up and designed in such a way that it is also able to measure the ambient temperature Tamb, Tambj in an environment U around the settable composition 4, in particular in an environment U above the settable composition. Alternatively, a separate temperature detection device can of course be provided for measuring the ambient temperature Tamb, Tamb . The ambient temperature Tamb, Tambj is detected at at least one point j, in particular at all points j=i. The area vertically above the settable composition 4 is defined as the environment U.

[0066] The surface temperatures Twrecorded at the points i are used together with the associated ambient temperatures Tamb, Tamb,mO) to calculate a corrected plate temperature TCOrrj at the points i according to the following formula: wherein

[0067] - i is a location at which the surface temperature Tb is measured,

[0068] - j is a location at which the ambient temperature Tambj is measured,

[0069] - m is a running variable that represents an m-th location i,

[0070] - m(j) is a location j that is located closest to an m-th location i and that is assigned to the m-th location i,

[0071] - Tcorr is the corrected plate temperature at location i, - Tb is the measured surface temperature at location i,

[0072] - Tb,m is the measured surface temperature at the m-th location i

[0073] - Tamb.mQ) is the ambient temperature Tambj measured at a location j closest to the m-th location i, in particular measured above the settable composition 4 assigned to the m-th location i - Atmis a time period required for a certain volume of settable composition 4 to move from the (m-1)-th position i to the subsequent m-th position i along the conveying direction (F)

[0074] - K is an experimentally determined total correction factor having the dimension [1 / s]

[0075] A sigmoid function is approximated to the corrected discrete plate temperatures TCOrr,i calculated according to the above formula, which are based on the surface temperatures Twor times t measured along the settable composition 4 after a certain period of time after the slurry has been applied, using an approximation algorithm. This approximation is carried out using conventional methods, for example the method of least squares. This sigmoid function produces a continuous, no longer discrete, temperature curve TCOrr(t) over time from the application of the slurry of the settable composition 4 or a continuous, no longer discrete, temperature curve Tcorr(d) over distance from the beginning of the setting distance D.

[0076] Figure 2 shows a section 20 of a production line 1 according to the invention, with the section 20 extending between the application device 3, for example the mixer, and the cutting device 6. The settable composition 4 can be conveyed in the conveying direction F at a belt speed v by means of the front device 11. The belt speed v causes a relative movement of the surface of the settable composition 4 with respect to the ambient air of the same magnitude, which, depending on the magnitude of the belt speed v, ensures a changed heat transfer between the settable composition and the environment. This results in a cooling effect.

[0077] According to the invention, the cooling effect of the heat transfer between the surface of the settable composition 4 and the environment U is taken into account. The measured temperatures Tbare corrected according to the invention in such a way that the heat transfer at the top of the settable composition 4 to the environment U is included in the calculation of the corrected temperature values. Such a heat transfer between the upper side of the settable composition 4 and the environment U is conveniently determined for a belt reference speed v0. If, in a specific application, the belt speed v is increased or reduced relative to the belt reference speed Vo, the correspondingly increased or reduced heat transfer can be adequately taken into account with an operational factor (v / v0)0 8representing the operation characteristics of the conveyor 11. For only minor deviations of the belt speed v from the reference belt speed v0, this factor can also be assumed to be approximately equal to 1 .

[0078] Further, material specific properties of the settable composition 4 are taken into account by a material factor wherein k is a heat transfer coefficient in [W / m2K] of the settable composition (4) to the environment (U), in particular to the environment (U) above the settable composition (4), p is a density in [kg / m3] of the settable composition (4), c is a specific heat capacity [J / kgK] of the settable composition (4),

[0079] Finally, a geometric factor 1 / h representing geometric properties of the settable composition is considered wherein h is a thickness of the settable composition 4. All in all, the operational factor, the material factor and the geometric factor are represented by the total correction factor K=— p*c - h (— )°'8which is used to determine the corrected plate temperature TCOrr,i at location i.

[0080] In the schematic representation of an embodiment of the invention according to section 20, the nine temperature detection devices 10 are evenly spaced along the setting line D. Of course, it is also possible to increase or, for example, to reduce the number of temperature detection devices 10 along the setting line D in order to increase the detection accuracy. Alternatively, the distance between two successive temperature detection devices 10 along the setting line D can be uneven, as shown in the example. For example, a higher number of temperature detection devices 10 can be used per section of the setting line D in a certain area where a higher level of recording accuracy is required.

[0081] Figure 3a shows a diagram in which the temperature curves of the measured surface temperatures Twof a certain settable composition 4 in different runs at different times (December 15, 2022, afternoon and December 16, 2022, morning) without taking into account an ambient temperature Tamb, Tamb,i and without the resulting corrected plate temperature TCOrr,i. A mostly linear increase or even partly a decrease of the measured temperature data (surface temperatures Tb,o is significant. This quality of raw data is not sufficient to derive meaningful conditions regarding a setting time and / or an actual degree of hydration.

[0082] One temperature curve (December 16, 2022, 9:30 a.m.) deviates significantly from the other three temperature curves and would therefore provide a distorted statement about the actual degree of hydration. In the legend for Figure 3A, the description of the measuring point symbols at the end includes the respective meter information in brackets, with these meter information being 244 m, 259 m, 208 m and 246 m in the examples. These distances are the distances from the application device in meters, which are determined from the parallel / simultaneous measurements using the AT-line-TRS measurement of the distance of the turning point W from the mixer 3, i.e. the determined distance of the turning point W from the application device.

[0083] Figure 3b shows the measured temperature curve Tb,i and the invention-related corrected temperature curve Tcorr(d) in relation to the corrected plate temperatures TCOrr,i for two different settable compositions (FHB and Habito). The corrected temperature curves TCOrr(d) are consistently above the corresponding, uncorrected temperature curves Tb. A time span tAis determined on the basis of the position of a turning point W, at which the maximum gradient of the approximated sigmoid function, which is approximated to the discrete points of the corrected plate temperatures TCOrr,i, with the distance from the application device and a known conveying speed in the conveying direction F. The time t required to cover the distance from an application point of the settable composition 4 to the turning point W is defined as the setting time tA.

[0084] Figure 6 below shows an example of how an actual degree of hydration can be determined at a specific point P. Knowing the approximate sigmoid curve TCOrr(t), a total temperature increase ATCOrr,ges is determined. It is assumed that a degree of hydration of 100% of composition 4 is reached after the total temperature increase ATCOrr,ges has been reached. In order to determine the actual degree of hydration at any given position P, the corrected temperature ATCOrr(P) corresponding to position P is determined using the sigmoid curve. A temperature increase ATCOrr(t) over time is calculated from the difference between the corrected temperature ATcorr(P) corresponding to position P and a corrected initial temperature TCOrr, start, which is determined, for example, at the point i=1 or is taken from the sigmoid curve at a point before the point i=1 , for example.

[0085] A ratio of the temperature increase ATCOrr(t) up to position P to the total temperature increase ATCOrr,ges is defined as the actual degree of hydration at position P. If the actual degree of hydration at position P is too far removed from the target degree of hydration, the actual degree of hydration at position P can be brought closer to the target degree of hydration by influencing the composition of the composition 4, for example by adding or reducing a hydration accelerator.

[0086] One possible application of this is, for example, to set an actual hydration level at a point PC where the cutting device 6 is located that is sufficient for the cutting process there.

[0087] Thus, the invention makes it possible to continuously provide online information on the hydration level at a given point P. An AT-line measurement to be carried out in parallel is no longer necessary.

[0088] The following describes the method according to the invention for determining an actual degree of hydration at a position P and / or the setting time tAaccording to the invention, using the steps S 101 to S 105 as an example.

[0089] In step S 101 , a settable composition 4 is first conveyed in a conveying direction F of a setting line D. This is done, for example, at a belt speed v that may be greater than, equal to or less than a reference belt speed v0.

[0090] In step S 102, a plurality of discrete surface temperatures Tb of the settable composition 4 along the setting line D and at least one ambient temperature Tamb,’ Tambj are measured. This is preferably done in a non-contact manner, for example using infrared thermometers.

[0091] From the discrete measured surface temperatures Tb and the at least one ambient temperature Tamb,’ Tambj, discrete corrected plate temperatures TCOrrj are calculated, these corrected plate temperatures Tcorrj in particular take into account a heat transfer between an upper side of the settable composition 4 and an upper-side environment U above the settable composition 4 (step S 103).

[0092] A sigmoid function can be fitted to the discrete, calculated, corrected plate temperatures Tcorr, i, which represents a temperature curve TCOrr(t) over time or a temperature curve TCOrr(d) over distance (step S 104). In a step S 105, the setting time tAand / or the actual degree of hydration at at least one position P is determined on the basis of characteristic parameters of the adapted sigmoid function. For example, a characteristic parameter of the sigmoid function in the form of a turning point W is suitable for determining the setting time. The time from the application of the settable composition 4 to the point at which the inflection point W is reached is conveniently defined as the setting time tA. An actual degree of hydration can, for example, be defined by relating a temperature change ATCOrr(d) up to a certain position P at a distance from the application area of the settable composition 4 to the sigmoid function, or a temperature change ATCOrr(t) up to a certain time t since the application of the settable composition 4 to the adjusted sigmoid function, to a total temperature change ATCOrr,ges of the settable composition 4 over the entire setting distance D. The resulting percentage value is defined as the actual degree of hydration in percent.

[0093] The following Figure 5 illustrates the method according to the invention for providing a target degree of hydration of an exothermically settable composition 4 at a predetermined position P of a setting distance D.

[0094] First, in a step S 201, the actual degree of hydration at a position P is determined using the above-described method for determining an actual degree of hydration.

[0095] Subsequently, in a step S 202, a check is made to see whether the actual degree of hydration of the settable composition 4 at the position P deviates from the desired degree of hydration at the position P by more than a predetermined degree of hydration tolerance at the position P. If this is the case, an adjustment of a composition of the settable composition 4 is made in a step S 203. This is done by increasing or reducing the addition of a setting accelerator to the slurry of the settable composition 4.

[0096] If the actual degree of hydration of the settable composition 4 at position P is within the degree of hydration tolerance at this position P, no adjustment of the composition of the composition by changing the addition of setting accelerator is required.

[0097] The procedure described above can then be repeated after a predetermined time window, which can be in the range of minutes or hours, or continuously, in order to ensure continuous monitoring of the actual degree of hydration at position P. In particular, position P is a position at or just before the cutting device 6, since at this point a particular compliance with a minimum actual hydration level is necessary. For example, cutting plasterboard at the cutting device 6 usually requires a minimum actual hydration level of greater than or equal to 50%. List of reference signs

[0098] 1 Production line

[0099] 2 Plasterboard products, plasterboard

[0100] 3 Application device, mixer

[0101] 4 Settable composition

[0102] 5 First cardboard layer

[0103] 6 Cutting device

[0104] 7 Turning station

[0105] 8 Dryer

[0106] 9 Palletizer

[0107] 10 Temperature detection device

[0108] 11 Conveyor

[0109] 20 Section

[0110] F Conveying direction

[0111] D Setting line

[0112] TCOrr(t) Temporal temperature curve

[0113] Tcorr(d) Line-related temperature curve tASetting time dASetting distance

[0114] Tb,i Measured surface temperature at point i

[0115] P Position

[0116] Tamb,’ Tamb,j Ambient temperature twTime coordinate of the turning point dwcoordinate of the turning point

[0117] W turning point

[0118] ATcorr(d) temperature increase over the length of the line

[0119] ATCOrr(t) temperature increase over time

[0120] ATcorr.ges total temperature increase i position at which the surface temperature Tb,i is measured j position at which the ambient temperature Tamb,j is measured m Running variable representing an m-th position i m(j) Position j, which is closest to an m-th position i and which is assigned to the m-th position i k Heat transfer coefficient of the settable composition to the environment U

[0121] Tcorr.i Corrected plate temperature at position i h Thickness

[0122] K Correction factor v Conveyor belt speed

[0123] Vo Reference conveyor belt speed p Density of the settable composition c Heat capacity of the settable compositions

[0124] AtmTime interval required for a specific volume of settable composition to move from an (m-1)-th position i to a subsequent m-th position i along the conveying direction F

[0125] U Environment t Time

[0126] PC Position of the cutting device 6

[0127] 5101 Step

[0128] 5102 Step

[0129] 5103 Step

[0130] S 104 Step

[0131] S105 Step

[0132] S 201 Step

[0133] S 202 Step

[0134] S 203 Step

Claims

Claims1 . Method for determining a setting time and / or an actual degree of hydration of an exothermically settable composition (4) (hereinafter referred to as settable composition (4)), in particular a gypsum composition,- wherein the settable composition (4) is being conveyed in a conveying direction (F) along a setting line (D) and- discrete surface temperatures (Tbj) of the settable composition (4) are detected at at least a plurality of points (i) along the setting line (D) and an ambient temperature (Tamb,' Tambj), in particular above the settable composition (4), is detected at at least one point (j),- wherein discrete corrected plate temperatures (TCOrr,i) are calculated using the discrete measured surface temperatures (Tbj) and the at least one ambient temperature (Tamb, Tambj), and- a sigmoid function is adapted to the discrete corrected plate temperatures (TCOrr,i), which represents a time-related temperature curve TCOrr(t) or a distance-related temperature curve Tcorr(d), and- the setting time (tA) and / or the degree of hydration of the settable composition (4) is determined at at least one position (P) of the setting line (D) on the basis of characteristic parameters of the adapted sigmoid function.

2. Method according to claim 1, characterized in that a time coordinate (tw) or a distance coordinate (dw) of a turning point (W) of the sigmoid function is defined as setting time (tA) or as setting distance (dA).

3. Method according to claim 1, characterized in that a time coordinate (tw) or a distance coordinate (dw) of a point of maximum slope of the sigmoid function is defined as setting time (tA) or as setting distance (dA).

4. Method according to claim 1, characterized in that a ratio of a temporal temperature increase (ATCOrr(t)) at a point in time (t) to a total temperature increase (ATges) or a ratio of a distance-related temperature increase (ATcorr(d)) at the position (P) to a total temperature increase (ATCOrr,ges) is defined as the actual degree of hydration.

5. Method according to any one of claims 1 to 4, characterized in that, for the purpose of calculating the corrected plate temperature (TCOrr,i), at least one, preferably all of the following assumptions are made for the sake of simplification:- no heat is transported from the interior of the settable composition (4) to an environment (U) on the underside or to an environment (U) on the edge sides of the settable composition (4),- ideal heat transport occurs within the settable composition (4);- a temperature curve TCOrr(t) is constant between two points i;- a heat transfer coefficient k between the settable composition (4) and the environment (U) does not depend on an ambient air temperature or an ambient air humidity.

6. Method according to any one of the preceding claims, characterized in that the surface temperature (Tb ) is measured at at least 4 points (i), preferably the surface temperature (Tb ) and the ambient temperature (Tambj) are measured at 9 points (i,j).

7. Method according to any one of the preceding claims, characterized in that the corrected plate temperature (Tcorrj) is calculated as indicated below:wherein- i is a location at which the surface temperature Tbis measured,- j is a location at which the ambient temperature Tambj is measured,- m is a running variable representing an m-th location i,- m(j) is a location j that is located closest to an m-th location i and that is assigned to the m-th location i,- Tcorr is the corrected plate temperature at the location i,- Tbis the measured surface temperature at the location i,- Tb,m is the measured surface temperature at the m-th location i,- Tamb.mQ) is the ambient temperature Tambj measured at a location j closest to the m-th location i, in particular measured above the settable composition (4) which is assigned to the m-th location i,- Atmis a time period which a certain volume of the settable composition (4) requires from the (m-1)-th position i to the subsequent m-th position i along the conveying direction (F),- K is an experimentally determined correction factor having the dimension [1 / s],8. Method according to claim 7, characterized in that the number of locations is j>1, wherein in particular the number of locations j is equal to the number of locations (i), i.e. the ambient temperature (Tambj) is measured at all locations (i), or alternatively the number of locations (j) is smaller than the number of locations (i), i.e. the ambient temperature (Tambj) is measured at fewer locations (j) than there are locations (i), the ambient temperature (Tambj) is measured, and the corrected surface temperature (TCOrrj) correlates the measured surface temperature (Tb,m) of the m-th location (i) with that measured value of the ambient temperature (Tamb,mO)) whose location (j) is located closest to the m-th location (i).

9. Method according to any one of the preceding claims, characterized in that the correction factor (K) for a settable composition (4) is determined experimentally in the course of AT-line measurements.

10. Method according to any one of the preceding claims, characterized in that the correction factor K for a settable composition (4) is determined experimentally according to the formula| / _k 1zJL'jO.s p*c hVV()Whereink is a heat transfer coefficient in [W / m2K] of the settable composition (4) to the environment (U), in particular to the environment (U) above the settable composition (4),p is a density in [kg / m3] of the settable composition (4), c is a specific heat capacity [J / kgK] of the settable composition (4), h in [m] is a thickness of the settable composition (4), is an optional correction factor which, for further simplification, can also be assumed to have the value 1 , taking into account an instantaneous belt speed v and a reference belt speed v0.11 . Method according to any one of the preceding claims, characterized in that the surface temperatures (Tb ) are measured contactlessly.

12. Method according to any one of the preceding claims, characterized in that the method is applied to exothermically settable compositions (4), e.g. one or more of the following settable compositions (4):- cement compositions, e.g. Portland cements, Sorel cements- gypsum compositions.

13. Method for providing a target degree of hydration of an exothermically settable composition (4) at a predetermined position (P) of a setting line (D) in a production line (1 ), wherein by means of the method according to any one of claims 1 to 12 the actual degree of hydration at the position (P) is determined and wherein, if the actual degree of hydration of the settable composition (4) at the position (P) deviates from the target degree of hydration at the position (P) by more than a degree of hydration tolerance at the position (P), a mass composition of the settable composition (4) in an application device (3), in particular a mixer (3) of the production line (1 ), is adjusted until the actual degree of hydration at the position (P) is within the degree of hydration tolerance at the position (P).

14. Method according to claim 13, characterized in that the mass composition is adjusted by increasing or reducing a proportion of a setting accelerator.

15. Section of a production line for products comprising settable compositions (4), in particular a setting section (D) of a production line (1 ) for plate-shaped gypsum products, for carrying out the method according to any one of claims 1 to 12 and for carrying out the method according to one of claims 13 and 14, the section extending between an applicator (3) for a slurry of the settable composition (4) and a cutting device (6) for separating an at least partially set settable composition (4), and the settable composition (4) being conveyable along the setting line (D) by means of a conveyor along the conveying direction (F), characterized in that at least one temperature detection device (10) each is arranged at at least a plurality of points (i) along the setting line (D), which devices are set up and designed to measure at least the surface temperature (Tb ) of the settable composition at point i and, in particular, along the setting line D, at least at one or more points j, a temperature detection device (10) is provided which is set up and designed to measure an ambient temperature (Tamb; Tamb,j) of an environment (U), in particular above the settable composition (4).

16. Section of a production line according to claim 15, characterized in that the number of positions (i) is at least 4, in particular 9, and the number of positions (j) is at least 1, wherein in particular the number of positions (i) is equal to the number of positions (j).

17. Section of a production line according to claim 15 or 16, characterized in that the application device (3) is a mixer (3) of a production line (1 ) for gypsum products and the cutting device (6) is a cutting device (6) for plate-shaped gypsum products (2).

18. Section of a production line according to any one of claims 15 to 17, characterized in that the temperature detection devices (10) are designed and set up to measure both the surface temperature (Tb ) of the at least partially set settable composition (4) and the ambient temperature (Tambj) at each point (i).

19. Section of a production line according to any one of claims 15 to 18, characterized in that the temperature detection devices (10) are arranged uniformly distributed along the setting line (D) or are arranged along a section of the setting line (D) in the conveying direction (F) at a closer distance to each other or at a greater distance from each other compared to the remaining setting line (D).

20. Section of a production line according to any one of claims 15 to 19, characterized in that means are provided for detecting a conveying speed (v) of the at least set settable composition (4).

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