DEVICE FOR TEMPERATURE CONTROL OF FLUIDS

Description

[0001] The invention relates to a device for controlling the temperature of fluids, in particular for controlling the temperature of fluids in a pipeline, a channel of any cross-section, or a container. Furthermore, the invention relates to a method for controlling the temperature of fluids using the device.

[0002] Currently, temperature control is typically achieved using temperature control lines through which a temperature control medium flows. These lines are, for example, integrated into the pipes or ducts carrying the medium. Electrical heaters are also used, particularly to prevent heat loss to the environment, which can lead to undesirable or impermissible cooling of the medium. These heaters are inexpensive and can be installed flexibly. Such temperature control devices are either applied directly to the outside wall of the pipe, duct, or container, or positioned inside the pipe, duct, or container. When using temperature control media, it is also common to provide a double jacket that forms the outer wall of the pipe, duct, or container.

[0003] DE102017207587A1 shows an underground pipe for receiving fluids or energy lines, wherein the pipe has a pipe wall through which at least one wall channel runs parallel to the longitudinal direction of the pipe, wherein a fluid medium is transmitted through the wall channel.

[0004] Very special requirements exist when it is necessary to avoid both excessively high and excessively low temperatures of the medium, especially when these are safety-relevant conditions.Particularly when temperature-sensitive fluids are to be tempered, there is a risk of local overheating occurring with electrical heating, which is essentially an intrinsic problem of these electrical heating devices, since each heating conductor always emits energy over the entire length or in sections with a uniform heat output per length, but the thermal contact of this heater to the medium-carrying pipe or duct always shows a certain inconsistency in the actual technical design and, moreover, temperature measuring points used for temperature control or limitation can only be set selectively, which means that there is a risk that local overheating can easily occur and this is not detected and not regulated.

[0005] The use of temperature control media, which can be continuously and safely limited against both excessively high and excessively low temperatures using known technical means, has the disadvantage that with increasing flow path - connecting pipes, for example in chemical production plants and in particular for connecting the production plants with their tank farms or port tank farms orConnecting pipelines in these tank farms themselves or in port tank farms where chemicals are temporarily stored in large quantities can easily be several hundred meters or even several kilometers long - when the fluid is heated, the temperature of the tempering medium decreases or when it is cooled, the temperature of the tempering medium increases, depending on the ambient conditions, which can vary considerably both over the seasons and even during the alternation of day and night, so that, particularly in long pipelines or channels, sufficient heat supply or heat removal over the entire length of the pipeline or channel can only be guaranteed with difficulty and only at very high technical and therefore (possibly uneconomical) expense or not sufficiently safely.

[0006] According to the state of the art, additional organizational effort is therefore regularly required, e.g. for regular and frequent inspections with their documentation, in order to achieve an appropriately well-functional and safe operation with such trace heating systems.

[0007] An important boundary condition to be observed is that not only the regular operating conditions with normal flow on the product side are taken into account - when the considerable heat content of the product medium means that the influence of external conditions on its temperature is very limited and therefore low - but also those that basically occur regularly and not infrequently, if not regularly, and which set the more demanding conditions in terms of heat supply and heat removal and during which the product medium lines remain full. This could, for example, be a strong reduction or interruption of the flow with the resulting stagnation of the flow of the product medium or its standstill, which can already occur with a normal stop, e.g.of feed pumps at the end of a transfer process, or automated closing or switching of pipeline valves, which can also occur due to mechanical or electrical faults in the system and the periphery of the pipeline.

[0008] The object of the present invention is therefore to provide a device and a method for tempering fluids which enable uniform tempering of a medium to be tempered without local overheating and at the same time, even in long pipelines or ducts, sufficient heat input or heat removal to maintain a desired and permissible temperature window or the avoidance and prevention of undesired or inadmissible heat input or heat removal from the environment, taking into account local environmental conditions and the operating conditions over the entire length of the pipeline or duct at reasonable costs, wherein the framework of different climatic zones is advantageously also taken into account.

[0009] The object is achieved by a device for tempering fluids, comprising a wall, a first insulating layer, a tempering means, and a second insulating layer, wherein the wall is in contact with the fluid to be tempered on one side, the first insulating layer is applied to the side of the wall facing away from the fluid, and the tempering means are arranged between the first and second insulating layers. Furthermore, the object is achieved by a method for tempering a fluid in a pipeline, a channel with any cross-section, or a container using such a device, wherein the tempering means are controlled such that heating power is only applied when the ambient temperature is lower than a permissible minimum temperature of the fluid and / or cooling power is only applied when the ambient temperature is higher than a permissible maximum temperature of the fluid.

[0010] The term "temperature control" within the meaning of the present invention encompasses not only the heating or cooling of the fluid, but in particular also the maintenance of the temperature of the fluid by preventing heat from being released from the fluid to the environment, which can lead to the fluid freezing or, particularly at high outside temperatures and high solar radiation, the fluid being heated to an unacceptable temperature. The latter can lead to a loss of effectiveness of inhibitors due to their increased reactive consumption, while the former can mean a loss of effectiveness of the inhibitors, for example, through crystallization due to decreasing solubility of the inhibitors in at least a portion of the fluid. An uncontrolled reaction, in particular polymerization, can be promoted, or the fluid can decompose.

[0011] The arrangement of the temperature control means between the first insulation layer and the second insulation layer ensures, particularly when using electrical heating, that no local overheating can occur, since the first insulation layer prevents the heat from the electrical heating from being transferred directly to the fluid through the generally highly heat-conducting wall of the pipe, channel or container.

[0012] The arrangement of the temperature control means between the first insulation layer and the second insulation layer also results in a smaller portion of the heat released or absorbed by the temperature control means being used to control the temperature of the fluid than if the temperature control means were arranged between the wall and only one insulation layer. This also prevents possible local overheating or undercooling of the fluid. In particular, this makes it possible to prevent internal heating of the fluid at ambient temperatures below or well below the desired and permissible fluid temperature.

[0013] To simplify the installation of the temperature control means and to achieve a more even distribution of the supplied or dissipated heat over the circumference of the pipeline or duct, it is further preferred if an intermediate layer made of a metal with a thickness in the range of 0.2 to 1 mm, in particular with a thickness in the range of 0.3 to 0.6 mm, is accommodated between the first insulation layer and the second insulation layer. The metal from which the intermediate layer is made is particularly preferably aluminum or copper, in particular aluminum. To be able to install the intermediate layer easily, it is further advantageous if it has two half-shells that are mounted around the first insulation layer.

[0014] The fluid to be tempered can be any flowable fluid, for example a fluidized solid, in particular a fluidized powder or granulate, a liquid or a gas, or any mixture thereof. The fluid to be tempered is particularly preferably a liquid, and in particular liquid acrylic acid or methacrylic acid. The liquid acrylic acid or methacrylic acid generally contains an inhibitor to prevent polymerization. Inhibitors used include, for example, dissolved oxygen, dissolved oxygen together with hydroquinone monomethyl ether, or dissolved phenothiazine. If hydroquinone monomethyl ether is used as an inhibitor, it is preferably used at a concentration in the range of 10 to 300 ppm.If the acrylic acid or methacrylic acid is not stored for an extended period, but is fed directly from production to further processing via a suitable pipeline, for example, and is only temporarily buffered, it is sufficient to use the hydroquinone monomethyl ether at a concentration in the range of 30 to 80 ppm. This enables direct further processing without first removing the inhibitor from the acrylic acid or methacrylic acid by suitable methods known to those skilled in the art. However, if the acrylic acid or methacrylic acid is intended to be stored for an extended period, for example for sale or shipment, for example for transport by ship, rail, or truck, the proportion of hydroquinone monomethyl ether is preferably in the range of 150 to 250 ppm, for example 200 ppm.Phenothiazine as an inhibitor is usually used at a concentration in the range of 5 to 300 ppm, usually up to a maximum of 100 ppm.

[0015] The permissible minimum temperature of the fluid is, for example, the solidification temperature. Cooling the fluid below the permissible minimum temperature would then cause the fluid to solidify and thus, for example, block a pipeline or a channel. If the fluid is in a container, the solidification of even just a part of the fluid can block an outlet from the container, so that the fluid can no longer be removed or the solidified part remains in the container and is therefore no longer accessible. The permissible maximum temperature is, for example, the decomposition temperature of the fluid or if the fluid tends to polymerize at certain temperatures. This is particularly true for a variety of ethylenically unsaturated substances, which include (meth)acrylic monomers, but also, for example,For styrene and vinylformamide, temperature thresholds are known and defined which must not be exceeded in order to effectively prevent the reduction and / or loss of effectiveness of existing inhibitors (such as hydroquinone monomethyl ether and oxygen dissolved in the fluid) or even the direct onset of chemical reaction (usually radical polymerization).

[0016] A chemical reaction, be it oligomer formation, polymerization, or even decomposition of the fluid, should or must generally be prevented. Since this can lead to uncontrolled heat input with possible gas formation, increased pressure, and possibly leakage or bursting of the pipe or duct, it is necessary to keep the temperature below defined thresholds. For controlling the heating or cooling capacity, it may be useful to provide a safety margin for both the permissible minimum and maximum temperatures. The permissible minimum temperature is preferably 0 to 5 K above the solidification temperature, and the permissible maximum temperature is 0.5 to 5 K below the decomposition temperature or the polymerization start temperature.The polymerization start temperature is the temperature at which at least one component of the fluid begins to polymerize. The polymerization start temperature may also depend on whether an inhibitor is present. If the first component of the fluid only begins to polymerize at a higher temperature when an inhibitor is used than without the use of the inhibitor, the polymerization start temperature is understood in the context of the present invention not to be the temperature at which the component generally begins to polymerize, but rather the temperature at which the component begins to polymerize despite the use of the inhibitor. This temperature is generally higher than without the use of the inhibitor.

[0017] The wall, which is in contact with the fluid to be tempered on one side and on which the insulating layer is applied on the side facing away from the fluid, is preferably a wall of a pipe through which the fluid flows or of a channel through which the fluid flows, with any cross-sectional shape, or a wall of a container containing the fluid. Particularly preferably, the device for tempering fluids is used on a pipe or channel with any cross-sectional shape, so that the wall is, in particular, a wall of a pipe or channel with any cross-sectional shape.

[0018] For the purposes of the present invention, a pipeline is understood to be a fluid-carrying line with a round cross-section, whereby the pipeline can be rigid or flexible. A channel with any cross-sectional shape can be any channel that is completely closed. The cross-sectional shape of the channel can have any shape, for example in the form of a polygon with at least three corners, for example in the form of a triangle, a rectangle or square, a pentagon, a hexagon or an octagon, or even in the form of an oval or with at least one curved wall and at least one flat wall or even with at least two curved walls, which can have different radii or also have the same radius and an angle at the junction of the walls. The wall is very particularly preferably the wall of a pipeline or a channel with an oval or square cross-section.

[0019] To prevent overheating or undercooling of the fluid, it is preferred if the temperature control means can be operated with a predetermined heating or cooling output. This allows such an amount of heat to be supplied or removed that the temperature of the fluid can be maintained within a predetermined range. To regulate the heating or cooling output, it is further advantageous if the temperature of the fluid is measured at least at the outlet from the device being heated or cooled. More precise control of the heat to be supplied or removed is possible if the temperature is measured at several points and heat is supplied or removed depending on the temperature of the fluid.

[0020] To supply or remove heat, the temperature control means can be designed so that only one section of the wall can be controlled at a time. This allows the required heat to be supplied or removed specifically to the relevant sections. In this case, controlling the heat supply and / or heat removal also requires measuring the temperature at the inlet and outlet of a section and, based on these temperatures, supplying or removing the required amount of heat for heating or cooling.

[0021] Depending on whether a permissible maximum temperature should not be exceeded or a permissible minimum temperature should not be undercut, the temperature control means comprise a cooling device with which the fluid can be cooled or a heating device with which the fluid can be heated. If both a minimum temperature and a maximum temperature should not be undercut and exceeded, the temperature control means preferably comprise both a heating and a cooling device.

[0022] Any heating method known to those skilled in the art can be used, for example heating using a heating line through which a heating medium flows, or electric heating. Correspondingly, any cooling device known to those skilled in the art can be used, such as cooling using a cooling line through which a cooling medium flows, or electric cooling, for example using Peltier elements. When temperature is controlled using a heating medium or a cooling medium, it is preferred if the heating medium or the cooling medium is supplied at a predetermined temperature. The heating power or cooling power can then be adjusted using the flow rate of the heating medium or cooling medium. Increasing the flow rate means that more heat can be supplied or, correspondingly, more heat can be dissipated during cooling.Accordingly, a reduction in the flow rate leads to a reduction in the heat supplied or removed. Changing the flow rate allows for a faster response to changes in the ambient conditions or the temperature of the fluid flowing through the pipe or duct than changing the inlet temperature of the heating or cooling medium.

[0023] Since, when temperature control is carried out using a heating or cooling medium, for example steam, oil, or any other liquid heating medium or a liquid refrigerant, temperatures higher than the temperature of the heating medium or lower than the temperature of the cooling medium cannot occur, even at local hotspots where heating lines or cooling lines through which the heating medium or cooling medium flows are connected to the wall, the device according to the invention is particularly suitable for temperature control of a fluid using temperature control means that include electrical heating. The advantage of such electrical heating is that a defined heating output can be supplied, whereby typically or as a rule, the heating output is the same per unit length over the entire length of the electrical heating.A further advantage of electrical heating is that the heating output is constant across the entire surface to be tempered, whereas with a liquid or gaseous tempering medium, the temperature decreases over the length of the flow of the tempering medium when heated with the tempering medium, or increases when cooled with the tempering medium. This means that the greatest amount of heat can be transferred at the position at which the tempering medium can first transfer heat to the fluid to be tempered or can absorb heat from the fluid to be tempered. Particularly in very long pipes or ducts, this can mean that the heat to be transferred from the tempering medium is not sufficient across the entire length of the pipe or duct to prevent a maximum temperature from being exceeded or a minimum temperature from being undercut, depending on the ambient temperature.This deficiency can be mitigated to some extent by guiding partial streams of the medium separately in the flow direction and feeding them at positions further downstream, although this only results in a limited improvement in the stepped characteristics.

[0024] Particularly for temperature-sensitive fluids, it is therefore particularly preferred if the temperature control means comprise electrical heating. If cooling of the fluid is required, it is furthermore advantageous to provide electrical cooling, for example with Peltier elements, instead of a liquid or gaseous cooling medium. When using electrical heating in the form of heating conductors, it is furthermore preferred if an even number of heating conductors is provided. This has the advantage that the electrical connections of the heating conductors can be made at one end, thus simplifying assembly and in particular the electrical connection of the heating conductors. To enable the electrical connection at one end, two heating conductors, which can be operated with direct current or alternating current, are electrically connected to one another at the end opposite the electrical connection.

[0025] In particular, if heating is generally required to regulate the temperature of the fluid and cooling is only required in exceptional cases, for example, on very hot summer days, it is also possible to provide, for example, an electric heating system and a cooling line through which a cooling medium can flow, and to only allow the cooling medium to flow through this line when cooling is required. Of course, it is also possible to provide both electric heating and electric cooling if the temperature control means are to include both cooling and heating.

[0026] If the temperature control device is used for a fluid that cannot be overheated, or if the permissible maximum temperature of the fluid is above the usual maximum ambient temperature, it is not necessary to provide additional cooling. In this case, the temperature control means comprise only heating means, in particular electric heating.

[0027] However, according to the invention, it is also possible to permanently achieve advantageous, safe and desired compliance with the permissible temperature window of the medium for a relevant number of applications involving fluids which must not be overheated - acrylic acid and methacrylic acid being mentioned here in particular - by means of an inventive design and dimensioning of insulation and electrical heating without any cooling device.

[0028] Particularly when the wall is a wall of a channel or a pipeline, it is preferred if the electrical heating comprises at least one heating conductor which runs parallel to the flow direction of the fluid in the channel or pipeline or which is wound around the channel or pipeline. The number of heating conductors also depends on the heat output to be supplied. In particular, if a high heat output must be supplied in order to maintain the desired temperature of the fluid, it is advantageous to use several parallel heating conductors, since in this case the total heat output is distributed among the individual heating conductors. This also means that, for the same heat output, with an increasing number of heating conductors, the individual heating conductors can have a lower temperature and can therefore be dimensioned for a lower specific heat output.

[0029] Particularly with heating conductors running parallel to the flow direction, the greatest amount of heat is transferred over the shortest distance between the heating conductor and the wall. This can result in the fluid in the pipe not being heated evenly. Therefore, to ensure uniform temperature control of the fluid in the pipe or duct, it is preferable, especially when using only a few heating conductors, for example, when using three or fewer heating conductors, and especially when using only one heating conductor, if the heating conductor(s) are wrapped around the pipe or duct. In this case, heat is supplied evenly from all sides of the pipe or duct. Alternatively, uniform temperature control can also be achieved by using an intermediate layer made of a material with good thermal conductivity, particularly aluminum or copper.

[0030] Particularly preferably, the heating power supplied by the electrical heating is set such that the temperature control means have the same temperature as the fluid to be temperature-controlled. As a result, the temperature of the fluid to be temperature-controlled is kept constant and no cooling or heating occurs, so that local overheating or undercooling can also be prevented. In order to be able to operate the temperature control means such that the temperature of the temperature control means is the same as that of the fluid to be temperature-controlled, it is furthermore particularly advantageous if the temperature of the temperature control means is measured. In particular, if the temperature control means cover a large area or a long pipe or channel is to be temperature-controlled, it is furthermore advantageous if the temperature of the temperature control means is recorded at several points.

[0031] Furthermore, ambient temperature conditions relevant for temperature control are preferably considered, such as a representative local temperature, which also takes into account the influence of heat dissipation by radiation, especially in clear weather and the visibility of the medium line toward space, especially at night, as well as direct sunlight during the day. This is particularly important when there is high solar radiation during the day and a high ambient temperature, followed by a significant drop in temperature at night.

[0032] Any temperature sensing means known to those skilled in the art can be used to measure the temperature of the fluid and the temperature of the temperature control means. Suitable temperature sensing means include thermometers or temperature sensors, for example, resistance temperature sensors such as thermocouples or nickel- or platinum-based temperature sensors, such as PT100 temperature sensors, or infrared temperature sensors.

[0033] Any suitable insulation material can be used for the first and second insulation layers. Foam glass or fiber materials such as mineral fibers, glass fibers, or ceramic fibers, for example in the form of mineral wool, are particularly preferred for the first and second insulation layers. Preferably, insulation materials are used that are suitable and approved in terms of chemical compatibility and porosity in order to minimize risks in the event of fluid leaks, and that do not pose a fire hazard and also prevent moisture from penetrating from the outside. Therefore, foam glass is particularly preferred for the first insulation layer. It is possible to use different materials for the first and second insulation layers, or the same material.It is preferred to use the same material, in particular foam glass, for the first insulation layer and the second insulation layer, thereby avoiding a reduction in the overall insulation quality in the event of undesired insufficient tightness of the outer casing due to water ingress, for example due to rain or condensation of atmospheric moisture. It is also preferred to construct the first insulation layer from foam glass and the second insulation layer from mineral wool, which offers cost advantages while still providing the assured effect of preventing undue heating of the product fluid by the electric heater and simultaneously preventing undue cooling due to low outside temperatures. A possible disadvantage could be reduced heating protection with a wet second insulation layer in the case of high ambient temperatures and without a cooling device, but this could be compensated for by occasional inspections.

[0034] According to the invention, the choice of the layer thicknesses of the first and second insulation layers should not be primarily based on the usual criteria of an 'economical' insulation thickness according to the state of the art, but should mainly meet the product-specific requirements. The layer thickness of the first insulation layer and the second insulation layer can be different or the same. In a preferred variant, the first insulation layer and the second insulation layer have the same layer thickness because, purely due to the geometry, the outer surface of the second insulation layer, related to its length, is considerably larger than that of the first insulation layer and thus the heat output given off by the electrical heating is preferentially dissipated to the outside, i.e. to where the cooling environment is, so that the possibility of overheating of the product fluid is practically excluded, even at low flow speeds.Furthermore, the overall thickness of the insulation is kept small, which is advantageous for pipe laying and space requirements.

[0035] Exemplary model calculations for the technically relevant pipe diameters in such applications with nominal diameters of 50 mm = 2 inches, 80 mm = 3 inches, 100 mm = 4 inches, and 150 mm = 6 inches have shown that it is particularly preferable to design the first insulation layer with a thickness of 20 to 40 mm, more preferably 25 to 35 mm, for example, 30 mm, since this ensures that, regardless of the thickness of the outer insulation, practically no significant heating of the product fluid can occur during relevant periods (typically 24 hours, since prolonged flow cessation either indicates a fault that needs to be monitored and rectified, or the pipe string needs to be emptied during a scheduled operation). In the case of state-of-the-art electrical heating applied directly to the pipe with insulation directed only to the outside, an inadmissible heating of the product medium will regularly occur within the considered 24 hours.

[0036] The heat flow transferred through the first insulation layer towards the fluid and the heat flow transferred through the second insulation layer towards the environment depends on the material and thickness of the respective insulation layer and also on the temperature difference between the temperature control means and the fluid or between the temperature control means and the environment. The thickness or material of the first insulation layer and the second insulation layer can be selected depending on the heat flow to be transferred to the fluid or the environment. If the aim is to transfer the greatest possible heat flow to the fluid, it is advantageous to design the first insulation layer with a thinner layer than the second insulation layer and / or to select a material for the first insulation layer that has better thermal conductivity than the material of the second insulation layer.Accordingly, if only a small heat flow is to be transferred to the fluid, it is advantageous to design the first insulation layer with a greater layer thickness than the second insulation layer and / or to select a material for the second insulation layer that has better thermal conductivity than the material of the first insulation layer.

[0037] However, it is particularly preferred if the first insulation layer and the second insulation layer have the same thermal resistance. This means that the thermal conductivity and layer thickness of the first and second insulation layers are the same. This is achieved in particular by the material of the first insulation layer and the second insulation layer being the same. In particular, in pipelines, due to the outwardly increasing surface area of ​​the rotationally symmetric, cylindrical geometry for heat transfer, outward heat flow is always noticeably preferential to inward heat flow, especially for the most relevant pipeline (nominal) diameters of 50 mm = 2 inches to 100 mm = 4 inches.

[0038] To protect the second insulation layer and prevent it from being damaged, particularly by weather influences or penetrated by (rain)water, it is possible and recommended to apply a cover to the second insulation layer. Such a cover can be, for example, a metal casing, particularly galvanized or painted sheet metal, aluminum, or even stainless steel. The material selection typically follows the known recommendations and specifications for the respective product medium, but especially the given system safety requirements for the installation.

[0039] Embodiments of the invention are illustrated in the figures and are explained in more detail in the following description.

[0040] They show: Figure 1 shows a cross-section through a pipeline with the device according to the invention for tempering fluids; Figure 2 shows a temperature profile through the device for tempering fluids with an ambient temperature below the temperature of the fluid; Figure 3 shows a temperature profile through the device for tempering fluids with an ambient temperature above the temperature of the fluid; Figure 4 shows a temperature profile through the device for tempering fluids with an ambient temperature below the temperature of the fluid, wherein the heating power is regulated such that the tempering means have the same temperature as the fluid.

[0041] Figure 1 shows a cross-section through a pipeline with a device according to the invention for tempering fluids.

[0042] A pipeline 1 comprises a wall 3 enclosing an interior space 5 through which a fluid can flow. The wall 3 simultaneously serves as the wall of the device for controlling the temperature of fluids 7, which is in contact with the fluid on one side and has a first insulating layer 9 applied to the side facing away from the fluid. The first insulating layer 9 is enclosed by a second insulating layer 11.

[0043] According to the invention, temperature control means 13 are arranged between the first insulation layer 9 and the second insulation layer 11. Preferably, an intermediate layer 14 is also arranged between the first insulation layer 9 and the second insulation layer 11 to improve heat flow distribution and even out the temperature around the circumference. The intermediate layer 14 is preferably a thin metallic layer to which the temperature control means are attached. The intermediate layer 14 is made, for example, of aluminum with a thickness of 0.2 to 1 mm, preferably 0.3 to 0.5 mm, and is designed in two shells / halves for advantageous assembly. The temperature control means 13 can be electrical heating conductors, as shown here. In this case, the temperature control means 13 serve for heating, and it is only possible to supply heat to a fluid flowing through the pipeline 1.Due to the positioning of the temperature control means 13, in this case heat is also released to the outside, preferably or even almost exclusively, to the environment, thereby preventing local overheating from occurring on the wall 3 of the pipeline and also preventing the product medium from being significantly heated or even overheated.

[0044] In addition to the electrical heating conductors shown here, the temperature control means 13 can also be pipes or channels of any cross-section through which a heating or cooling medium flows, or heating or cooling elements of any other shape, for example, as flat elements applied to the first insulation layer 9. If the heating or cooling elements have any shape, electrical heating or cooling elements are used in particular.

[0045] If electrical heating conductors or pipes or ducts are used as the temperature control means 13, they can run parallel to the central axis of the pipe 1 or encircle the pipe 1, for example, in the form of a spiral. It is also possible for the temperature control means 13 to be applied in a meandering manner on the first insulation layer 9. This is particularly possible when using electrical heating conductors, since these provide a constant heat output over their entire length.Typically and preferably, for reasons of accessibility for assembly, a linear arrangement parallel to the central axis of the pipeline is used, wherein the heating conductor is preferably arranged slightly off the center on the underside (5 to 6 or 6 to 7 o'clock position) when only one heating conductor is used, the heating conductors are preferably arranged at the 7 to 8 o'clock and 4 to 5 o'clock positions when two heating conductors are used, preferably at the 8 o'clock, 12 o'clock and 4 o'clock positions when three heating conductors are used, and preferably at the 7 to 8 o'clock, 10 to 11 o'clock, 1 to 2 o'clock and 4 to 5 o'clock positions when four heating conductors are used. For an advantageous embodiment of the electrical connection, an even number of heating conductors is particularly preferred, since in this case both ends of the electrical connection of a linear, single-core heating conductor can be positioned locally at a common connection point.

[0046] To protect the material of the second insulation layer 11 and, in particular, to prevent aging or damage to the material of the second insulation layer 11 due to weather conditions or other environmental influences, it is particularly preferred if the second insulation layer is enclosed by a casing 15. The casing 15 is preferably made of a metal, for example, stainless steel, aluminum, zinc, or galvanized or painted steel or aluminum. As an alternative to using a metal for the casing 15, it is also possible to manufacture the casing 15 from a polymer material. However, the use of a metal is preferred.

[0047] The device for tempering fluids, for example, by the Figure 1 The temperature curve of the pipeline shown in cross-section is shown for three different variants in the Figures 2 to 4 shown.

[0048] In the Figures 2 to 4In each case, the abscissa represents the course through the device r from the interior of the device to the environment and the ordinate represents the temperature T. In all three figures, a vertical line 101 represents the position of the inside of the first insulation layer 9, a second vertical line 103 indicates the position at which the second insulation layer 11 rests on the first insulation layer 9 and a third vertical line 105 indicates the outside of the second insulation layer 11. The wall 3 of the pipeline or a container and the jacket 15 is shown in the Figures 2 to 4not included, since due to the small thickness of the wall 3 and the casing 15, as well as the commonly used material with good thermal conductivity, the temperature difference between the inside and outside of the wall 3 or the casing 15 is generally negligible compared to the temperature differences created by the insulating layers 9, 11. Furthermore, the influence of thermal radiation was not taken into account due to its small effects compared to thermal conduction and convection. The temperature gradients derived from the temperature representations can be assigned equivalently corresponding heat flows or resistances to heat transfer.

[0049] Figure 2 shows a temperature curve through the device for tempering fluids with an ambient temperature below the temperature of the fluid.

[0050] In particular, in the case of a well-mixed fluid or a pipeline with turbulent flow, the fluid inside the device for tempering a fluid has a substantially constant fluid temperature 107.

[0051] Due to heat conduction and convection, the temperature at the wall 3 of the pipe or container increases when, as in Figure 2 shown, the temperature 109 of the temperature control means 13 is higher than the fluid temperature 107. Due to the heat conduction through the first insulation layer 9, the temperature decreases from the outside to the inside, that is, from the temperature control means in the direction of the wall 3 of the pipe or container, so that in the first insulation layer 9 of the Figure 2shown linearly increasing temperature profile 111 from the fluid towards the temperature control means 13. Since heat is also transported through the second insulation layer 11, the temperature decreases here from the temperature control means 13 outwards according to the temperature profile 113 shown. On the outside of the second insulation layer 11 or the casing 15 (not shown here), the temperature decreases further due to heat conduction effects and convection until the ambient temperature 115 is reached at some distance from the second insulation layer 11 or the casing 15.

[0052] In contrast to the Figure 2 The temperature curve shown is in Figure 3a temperature profile is shown which results when the fluid temperature 107 is below the ambient temperature 115 and a cooling device is provided as the temperature control means 13. In order for the temperature control means 13 to be able to cool, it is necessary that the temperature 109 of the temperature control means 13 is below the fluid temperature 107. Due to the low temperature 109 of the temperature control means 13, the temperature of the fluid near the wall decreases due to heat conduction effects and convection, and in the first insulation layer 9, a linear temperature profile 111 results, with the temperature decreasing from the interior of the temperature control device towards the temperature control means 13. Due to the higher ambient temperature 115 outside the temperature control device, the temperature in the second insulation layer increases from the inside outwards towards the environment with a linear temperature profile 113.On the outer wall, there is again a non-linear temperature increase from the temperature of the outer wall to the ambient temperature 115 due to heat conduction and convection in the ambient air.

[0053] An ideal temperature profile is in Figure 4 As in Figure 2 Here the ambient temperature 115 is lower than the fluid temperature 107. However, in contrast to the Figure 2In the curve shown here, the amount of heat supplied by the temperature control means 13 is adjusted so that the temperature 109 of the temperature control means 13 corresponds to the fluid temperature 107. Due to the identical temperature of the temperature control means 13 and the fluid, a constant temperature results from the fluid through the wall 3 and the first insulation layer 9 up to the temperature control means 13, which are also arranged here between the first insulation layer 9 and the second insulation layer 11 at the position designated by line 103.

[0054] Due to the identical temperature 109 of the temperature control means 13 and the fluid, only a small amount is released into the interior of the device for temperature control of the fluid, for example, the pipeline or the container. A further portion is released to the outside, so that the temperature at the outer wall is higher than the ambient temperature 115. The heat is then released to the environment by conduction and convection, resulting in a nonlinear temperature drop from the temperature of the outside of the second insulation layer 11 or the casing 15 to the ambient temperature 115.

[0055] According to the temperature profile which is below the fluid temperature 107 here for an ambient temperature 115, it is also particularly advantageous if the ambient temperature is above the fluid temperature and the temperature control means also comprises a cooling device if the temperature control means can absorb so much heat that the temperature of the temperature control means is the same as the fluid temperature.

Claims

1. An apparatus for controlling the temperature of fluids, comprising a wall (3), a first insulation layer (9), means of temperature control (13), and a second insulation layer (11), where the wall (3) is in contact on one side with the fluid of which the temperature is to be controlled and the first insulation layer (9) has been applied to the side of the wall (3) facing away from the fluid, and the means of temperature control (13) are disposed between the first insulation layer (9) and the second insulation layer (11).

2. The apparatus according to claim 1, wherein the wall (3) is a wall of a pipeline (1) through which the fluid flows or a duct of any cross-sectional shape through which the fluid flows or a wall of a vessel comprising the fluid.

3. The apparatus according to claim 1 or 2, wherein the means of temperature control (13) can be operated with a defined heating output or cooling output.

4. The apparatus according to any of claims 1 to 3, wherein the means of temperature control (13) comprise an electrical heater.

5. The apparatus according to any of claims 1 to 4, wherein an interlayer of a metal having a thickness in the range from 0.2 to 1 mm is accommodated between the first insulation layer (9) and the second insulation layer (11).

6. The apparatus according to any of claims 1 to 5, wherein the wall (3) is a wall of a duct or of a pipeline (1) and the electrical heater comprises at least one heat conductor which runs parallel to the flow direction of the fluid in the duct or in the pipeline or which is wound around the duct or the pipeline (1), preferably with inclusion of an even number of heat conductors.

7. The apparatus according to any of claims 1 to 6, wherein the means of temperature control (13) comprise a cooling device, where the cooling device preferably comprises at least one cooling conduit through which a cooling medium flows.

8. The apparatus according to any of claims 1 to 7, wherein the first insulation layer (9) and the second insulation layer (11) have the same layer thickness.

9. The apparatus according to any of claims 1 to 8, wherein the first insulation layer (9) has a layer thickness in the range from 20 to 40 mm.

10. The apparatus according to any of claims 1 to 9, wherein the first insulation layer (9) and the second insulation layer (11) have the same heat resistance.

11. A method of controlling the temperature of a fluid in a pipeline (1), a duct of any cross section or a vessel with an apparatus (7) according to any of claims 1 to 10, wherein the means of temperature control (13) are actuated such that a heating output is applied only when the ambient temperature (115) is lower than a minimum permissible temperature of the fluid and / or a cooling output is applied only when the ambient temperature (115) is higher than the maximum permissible temperature of the fluid.

12. The method according to claim 11, wherein the heating output is adjusted such that the means of temperature control (13) are at the same temperature as the fluid of which the temperature is to be controlled.

13. The method according to claim 11 or 12, wherein the maximum permissible temperature is 0.5 to 5 K below the breakdown temperature of a component of the fluid or the polymerization initiation temperature and / or the minimum permissible temperature is 0 to 5 K above the solidification temperature of the fluid.

14. The method according to any of claims 11 to 13, wherein the fluid is methacrylic acid or acrylic acid stabilized by hydroquinone monomethyl ether together with dissolved oxygen or with phenothiazine.

15. The method according to any of claims 11 to 14, wherein the fluid is a fluidized solid, a liquid, a gas or any mixture thereof.