DE102009042994A1 - Method for monitoring operation of e.g. plate-type heat exchanger in chemical plant to control safety precautions, involves providing circuit e.g. valves, to control volumetric flow of fluid streams into apparatus depending on comparison - Google Patents

Abstract

The method involves measuring temperature (T1-T3) in local areas (23-25) within an apparatus i.e. plate-type heat exchanger (1) or an external wall (5) of the apparatus. The measured temperature is compared with a temperature target value stored in a control device (30) of a plant, where the temperature target value is measured from rigidity calculation of the local area. A circuit e.g. alarm device (50) or valves (V1, V2), is provided for controlling volumetric flow of fluid streams (F1, F2) flowing into the apparatus depending on the comparison. An independent claim is also included for a safety device for a process technical or chemical plant.

Description

The present invention relates to a method for safety-related monitoring of the operation of a thermally loaded apparatus, for example a heat exchanger or a chemical reactor, in a process engineering or chemical plant and optionally for controlling safety measures. Furthermore, the invention relates to a safety device for carrying out the method.

Many apparatuses of process engineering or chemical plants, such as heat exchangers or chemical reactors, are exposed to high temperature stresses during their operation, resulting for example from large temperature differences of inflowing fluids. In exothermic chemical reactions large amounts of heat can be released, which has a high stress on the apparatus due to thermal stresses in components of the apparatus result.

To avoid thermal stress damage, temperature measurements are made in the prior art on piping or fluid streams leading to or away from the particular apparatus. By means of these temperatures measured in the supply and discharge lines, the apparatuses are monitored for safety and safety measures are controlled.

As an example of this is a heat exchanger, such as a plate heat exchanger, called, in which a cryogenic first fluid flow (of for example -180 ° C) and a warm, second fluid flow (for example, of 40 ° C) are conducted in indirect heat exchange in countercurrent to each other. If, for example, the warm, first fluid flow fails in an accident, a temperature drop is registered at the discharge of the second fluid flow from the heat exchanger. This temperature drop is usually used as a criterion for initiating safety measures. A safety measure may be, for example, to close the valve controlling the cold flow. The cold stream can thus no longer flow into the heat exchanger. This is to prevent damage caused by unauthorized thermal stress on the heat exchanger.

However, the problem with this approach is that the temperature limits to initiate the safety measures, for example, the aforementioned closing of the valve in the cold stream, are very conservative, i. H. must be chosen closely to prevent damage to the heat exchanger safely. A frequent introduction of safety measures to protect the heat exchanger against unauthorized thermal stresses can significantly affect the entire operation of a system equipped with the heat exchanger. However, with widely chosen temperature limits, the heat exchanger is exposed to an increased risk of leakage due to local voltage overshoots. However, these are not covered by the prior art.

In the EP 1 798 508 A1 A method for determining the strength of a plate heat exchanger is described, in which the thermal stresses occurring during operation inside a plate heat exchanger are calculated by means of a three-dimensional numerical simulation, and the strength of the plate heat exchanger is determined on the basis of the calculated thermal stresses. To determine the spatial temperature distribution in the profiles and dividing plates, a simplified layer model is used in which the profile is modeled by a metal block homogeneously filling the space between the dividing plates. In addition to the temperatures, the operating pressures of the fluids, which cause pressure distribution in the heat exchanger, act on the plate heat exchanger. The total stress distribution is determined by superposition of the thermal stress distribution and compressive stress distribution. By means of the method described, stress ratios occurring for the plate heat exchanger during normal operation can be determined.

In a sudden accident in a system comprising the plate heat exchanger, such as a reduction or a failure of a fluid flowing into the plate heat exchanger, however, the local voltage distributions may abruptly change as indicated by the above calculations. Local excess voltage exposes the device to an increased risk of leakage.

The object of the present invention is therefore a method for safety monitoring of the operation of an apparatus in a process engineering or chemical plant and a To provide safety device for performing the method, which reliably prevent damage to the apparatus due to thermal stresses.

The object is achieved by a method according to claim 1 and a safety device according to claim 8. The dependent claims relate to preferred embodiments.

• (a) Messen zumindest einer Temperatur an zumindest einer lokalen, also örtlich begrenzten Stelle, innerhalb des Apparates oder an einer Außenwand des Apparates;
• (b) Vergleichen der gemessenen Temperatur oder eines aus einer oder mehreren der gemessenen Temperaturen berechneten Temperaturvergleichswertes, beispielsweise eines Temperaturdifferenzwertes oder Steigungswertes einer Temperaturkurve, mit einem in einer Steuereinrichtung der Anlage abgelegten Temperatursollwert oder Temperaturgrenzwert für die lokale/n Stelle/n, wobei der Temperatursollwert oder der Temperaturgrenzwert aus einer Festigkeitsberechnung für die lokale/n Stelle/n resultiert;
• (c) Ansteuern oder Nichtansteuern einer Schaltung, beispielsweise einer Alarmeinrichtung oder eines Ventils zur Steuerung des Volumenstroms zumindest eines der in den Apparat einströmenden Fluidströme, in Abhängigkeit des Vergleichs.

Accordingly, a method for safety monitoring of the operation of a thermally loaded apparatus, such as a heat exchanger or a chemical reactor, in a process engineering or chemical plant and optionally provided for the control of security measures. The method comprises the following steps:

• (A) measuring at least one temperature at at least one local, ie localized, location within the apparatus or on an outer wall of the apparatus;
• (b) comparing the measured temperature or a temperature comparison value calculated from one or more of the measured temperatures, for example a temperature difference value or slope value of a temperature curve, with a temperature setpoint or temperature limit for the local location (s) stored in a controller of the facility, the temperature setpoint or the temperature limit results from a strength calculation for the local site (s);
• (C) driving or Nichtansteuern a circuit, such as an alarm device or a valve for controlling the flow rate of at least one of the inflowing into the apparatus fluid flows, depending on the comparison.

Temperature measurements at local locations within the apparatus or on the outer wall of the apparatus can better monitor local thermal stresses. By comparing with temperature setpoints or limit values, which were determined from strength calculations for the local points, local thermal voltage excesses and thus damage to the device can be prevented by timely initiation of safety measures. The life of the apparatus is thereby increased. In addition, the apparatus can be operated in a wider temperature range.

In principle, it is possible to compare the absolute temperature measured values determined in step (a) with absolute temperature setpoints or temperature limit values in step (b). Such a procedure is suitable, for example, for monitoring the regular operation of an apparatus.

In addition, however, it is also possible to perform a comparison of relative temperature values. For safety-related monitoring of the startup of an apparatus, it is advantageous to monitor temperature difference values between local points of the apparatus. One approach could be to measure temperatures in step (a) at at least two local locations within the apparatus or on an outer wall of the apparatus, to form a differential value of both temperatures in step (b), which is compared to a temperature difference threshold consisting of a Strength calculation for the local bodies results. Upon reaching defined temperature limits, appropriate safety measures can be taken.

Another preferred procedure envisages calculating the slope of the temperature curve for at least one local location in step (b) and comparing it with a temperature slope limit value or temperature gradient setpoint for the local location. Depending on the result of this comparison, safety measures may be controlled if necessary. Such a procedure is also advantageous in the commissioning of apparatus. The slope values may be positive for actual increase, negative for decrease of the temperature curve.

A preferred safety measure is to trigger an alarm device in step (c) upon reaching a first temperature limit value, which emits an alarm signal, for example an optical and / or acoustic alarm signal. The operating staff is thus given the opportunity to return the temperature by suitable measures in the desired range. In a heat exchanger, such as a plate heat exchanger or a wound heat exchanger, are introduced into the at least two fluid streams for indirect heat exchange with each other, the operating personnel, for example, the volume flow of the fluids by operating the valves in the supply and / or discharge lines.

Upon reaching a second temperature limit, which is preferably above the first temperature limit or at minus temperatures below the first temperature limit, is Preferably, a valve for controlling the volume flow of at least one inflowing into the apparatus fluid flow is controlled. For example, the valve can be completely closed.

This results in a two-stage safety system, in which upon reaching a first temperature limit preferably first an alarm is issued. If control measures by the operating personnel do not take place or are not timely, when a second temperature limit value is reached, preferably a valve for controlling the volume flow of at least one fluid flow entering the apparatus is automatically actuated.

In general, however, it is also possible, for example, for safety-related monitoring of the regular operation of an apparatus by a control effect on local temperatures. Preferably, in step (c), by controlling at least one valve which serves to control the volume flow of at least one fluid stream flowing into the apparatus, the temperature at the local location (s) or the calculated temperature comparison value is at a predetermined set point Temperature range to be - or kept below or above a predetermined temperature limit for the local / n / n. This makes it possible to avoid local voltage excesses due to unauthorized local temperatures in the regular operation of the apparatus.

The evaluation of the measured temperatures taking place in step (b) can thus be based on: individual local temperatures, temperature profiles over time T (t) at a local measuring point or differential temperatures between two or more local temperatures at local points of the apparatus.

• (a) zumindest einen ersten Temperatursensor an zumindest einer lokalen Stelle innerhalb des Apparates oder an einer Außenwand des Apparates,
• (b) eine Steuereinrichtung, in der zumindest ein Temperaturgrenzwert oder zumindest ein Temperatursollwert abgelegt ist, der aus einer lokalen Festigkeitsberechnung für die lokale/n Stelle/n resultiert, und
• (c) eine Alarmeinrichtung zur Ausgabe eines Alarmsignals und/oder eine Schaltung zur Steuerung der Temperatur/en an der lokalen Stelle bzw. an den lokalen Stellen, insbesondere ein Ventil zur Steuerung des Volumenstroms zumindest eines in den Apparat einströmenden Fluidstroms.

To carry out the method according to the invention, a safety device for a process engineering or chemical plant is provided. This indicates:

• (a) at least one first temperature sensor at at least one local location within the apparatus or on an outer wall of the apparatus,
• (B) a control device in which at least one temperature limit value or at least one temperature setpoint is stored, which results from a local strength calculation for the local / n place / n, and
• (C) an alarm device for outputting an alarm signal and / or a circuit for controlling the temperature / s at the local location or at the local locations, in particular a valve for controlling the volume flow of at least one fluid stream flowing into the apparatus.

The method according to the invention or the safety device according to the invention can be used for safeguarding malfunctions, for example in the event of failure of an incoming fluid flow due to a pump failure, for monitoring the startup of an apparatus and for regulating local temperatures in the apparatus during normal operation.

The temperature data sets of temperature limit and / or temperature setpoints stored in the control device can originate from strength calculations which are carried out by the control device itself. In general, the data sets are determined by an independent, separate computer unit, stored in a memory and transmitted by the latter to a corresponding memory in the control device of the security device.

As temperature sensors, all known in the art sensors for detecting the temperature such as thermocouples can be used. For measuring temperatures on walls of the apparatus, contact thermometers or surface contact thermometers are preferably used. These may be thermometers with thermocouples (NiCr / Ni, Pt / PtRh, Fe / Constantan, etc.). Non-contact measuring thermometers such as radiation thermometers can also be used.

Preferably, the method according to the invention or the device according to the invention is used for apparatuses which have a high temperature response, ie. H. often large temperature changes, are exposed. Also in apparatuses with locally large temperature differences, the inventive method or the inventive device is advantageous.

Preferably, the inventive method or apparatus for plate heat exchanger or wound heat exchanger is used.

For plate heat exchangers, surface contact thermometers may be applied to the side bars. In wound heat exchangers, surface Contact thermometer on individual tubes or on the so-called. Shirt, which is arranged between the outer tube and the shell of the heat exchanger. Also in interspaces within the wound heat exchanger thermometers can be arranged. The measuring points can also be spaced from walls.

Preferably, the method or apparatus is used for heat exchangers which are used in plants for the liquefaction of natural gas, for cryogenic air separation or for the production of olefins. There, fluids usually enter the heat exchangers with large temperature differences. In liquefied natural gas plants, wound heat exchangers are often used to precool or subcool the main stream of material.

In a system for the cryogenic separation of air, the main heat exchanger can be secured by the method according to the invention or the device according to the invention. The fluids entering the main heat exchanger often have temperature differences of over 200K. The cold stream usually enters the heat exchanger at about -180 ° C, the warm stream at about + 40 ° C. In case of failure of one of the fluid streams, for example due to a pump failure, the local temperatures may change abruptly.

Local voltage overshoots can be the result. With the method according to the invention, these local temperatures are measured and compared with temperature data from local strength calculations. Local voltage overshoots can be prevented.

The inventive method or the safety device according to the invention can be used in a chemical reactor in which an exothermic chemical reaction takes place and the heat of reaction is removed by indirect heat exchange with a fluid flowing into the reactor. In such a reactor, for example, if the volume flow of the incoming cooling fluid is reduced due to a malfunction or if the cooling fluid flow is completely reduced, locally high temperature stresses can occur within the reactor, which jeopardize the strength of the apparatus. These can be revealed in good time by means of the method according to the invention or the safety device according to the invention.

The invention and further details of the invention are explained in more detail below with reference to the drawings described embodiments. Hereby shows:

1 a perspective, schematic representation of a plate heat exchanger with an embodiment of a safety device according to the present invention.

1 shows in perspective view a plate heat exchanger 1 , which is used in a plant for the cryogenic separation of air as a heat exchanger. The plate heat exchanger 1 includes a cuboid heat exchanger block 2 , On the front is the block 2 partially cut open. The heat exchanger block 2 includes a variety of dividers 3 and heat exchange profiles 4 , so-called fins 4 which are stacked alternately in a stack. The dividers 3 and the fins 4 are usually made of aluminum.

To their side are the fins 4 through end strips 6 , in English referred to as side bars, completed. By cover plates 7 are the front and the back of the cuboid 2 closed to the outside liquid-tight. The individual components of the cuboid 2 are connected by solder.

Between adjacent dividers 3 is in each case a liquid-tight passage with a fin plate 4 formed, through which a fluid can be performed for heat exchange. The block 2 has openings 9 and 10 for introducing the fluids into the respective passages of the block 2 on.

Often the passages show as in the EP 1 798 508 A1 in 3 shown, profiled distribution plates, which the fluid from an inlet opening over the entire width B of the fin 4 distribute, as well as profiled collecting sheets, the fluid over the width of the respective fin 4 merge to an outlet opening. In the present 1 the distributor and collector plates are not shown for reasons of clarity.

On the sides of the cuboid 2 there are essays 12 to 15 , which are called headers in English. The essays 12 to 15 are to the block 2 open channels, which is a circular segment Have cross section and are closed at their ends. At every essay 12 to 15 there is a nozzle 16 ,

The essays 12 and 13 distribute the inflowing fluids over the entire depth T of the heat exchange block 2 and thus over all entry openings shown in broken lines 9 and 10 , The essays 14 and 15 pick up the fluids leaving the passages, collect them and transfer them via the nozzles 16 in derivatives 20 and 21 one.

In the present example are in the plate heat exchanger 2 , which is located in a plant for cryogenic separation of air, two fluid streams F1 and F2 initiated for indirect heat exchange.

About the supply line 19 a cold fluid flow F1 is introduced at a temperature of about -179 ° C and over the supply line 18 a warm fluid flow F2 with a temperature of about 40 ° C. These swap in the passages of the heat exchanger block 2 by indirect heat exchange their heat energy.

About the tower 15 and the derivative 21 the heated fluid flow F1 leaves the block 2 , The fluid flow F1 has after the heat exchange in about a temperature of 35 ° C. The fluid flow F2, cooled to a temperature of about -170 ° C by heat exchange, leaves the heat exchange block 2 about the tower 14 and the derivative 20 ,

The volume flow of the fluid flow F1 is via a valve V1 in the supply line 19 and the volume flow of the fluid flow F2 via a valve V2 in the discharge 20 adjustable.

At the right side outer wall 5 the plate heat exchanger 1 are located at a passage for the fluid flow F1 more perpendicular to a terminal strip 6 superimposed local measuring points 23 . 24 and 25 , At these temperatures are detected by means of temperature sensors, not shown, for example, thermocouples, T1, T2 and T3. The temperature sensors are in contact with the surface of the end strip 6 , These are therefore contact thermometers or surface contact thermometers. The temperature sensors are each via data lines 33 . 34 and 35 with a control device 30 connected. The control device 30 may for example be part of a process control system of the plant for the cryogenic separation of air. Via a first control line 36 is the valve V1 from the controller 30 from the adjustment of the volume flow of the fluid flow F1 controllable and via a second control line 37 the valve V2 for adjusting the volume flow of the fluid flow F2.

The during operation through the heat exchanger 1 flowing fluid flows F1 and F2 generate in the baffles 3 and the heat exchange profiles 4 thermal stresses.

To prevent leakage of the plate heat exchanger 1 due to unauthorized thermal stresses are in the control device 30 for those of the temperature sensors at the measuring points 23 to 25 measured temperatures T1, T2 and T3 temperature setpoints and / or temperature limits are stored. This in the control device 30 stored temperature records are by a strength calculation of the heat exchanger 1 for the local measuring points 23 . 24 and 25 determined.

The usual procedure is, from strength parameters, for the heat exchanger 1 used materials to calculate maximum allowed voltages, and from this allowed temperature limits for the local measuring points 23 . 24 and 25 to determine and deposit in the controller. The calculation of the temperature limit values can be performed by the control device 30 yourself. However, it is also possible to calculate temperature limit values or setpoint values calculated in an external device to the control device 30 transferred to. The temperature limits may be during the total operating time of the plate heat exchanger 1 be renewed, for example, if the number of load changes in the strength calculation should be included again.

Furthermore, the system comprises a display unit 40 for example a screen 40 in which the measured local temperature values T1, T2 and T3 are displayed, for example in the form of temperature profiles plotted over time, T1 (t), T2 (t) and T3 (t). This screen 40 is advantageously located in a process control room 100 the plant. The temperature values T1 to T3 are transmitted via a data line 41 from the controller 30 to the screen 40 transfer. You can, however, also directly from the measuring points 23 to 25 to the screen 40 be transmitted.

The operation of the safety device described above will now be explained in more detail with reference to three scenarios:

Scenario 1: Safety monitoring of the regular operation of the plate heat exchanger

The control device 30 compares at regular time intervals at the temperature measuring point 24 measured temperature T2 (t) with a stored in the controller temperature setpoint T2soll for the local measuring point 24 , The temperature setpoint T2soll is from a strength calculation for the local measuring point 24 determined. In the event of deviations from the temperature setpoint T2setpoint, the control device controls 30 the valve V1 for controlling the volume flow of the fluid flow F1. The temperature T2 at the measuring point is determined by the volume flow of the fluid flow F1 24 changed. An increase in the volume flow of F1 causes a decrease in the temperature T2, a reduction in the volume flow an increase in the temperature T2.

This regulation makes it possible to leak at the plate heat exchanger 1 by avoiding frequent, high temperature changes.

Notwithstanding the present example, alternatively or additionally, temperature setpoints for the measuring points 23 and 25 in the control device 30 deposited and used for regulation.

Scenario 2: Safety-related monitoring and introduction of safety measures in the event of a malfunction

In the following scenario it is assumed that valve V2 closes due to a fault in the event of a malfunction. As a result, the temperature T2 decreases.

In the control device 30 are graded two temperature limits, which consist of a strength calculation for the local measuring point 24 were determined. A first temperature limit TSLa of -25 ° C in this example. And a second temperature limit TSLL of -30 ° C in this example.

The control device compares at regular time intervals the temperature T2 determined at the temperature measuring point with the abovementioned temperature limit values TSLa and TSLL.

If the first temperature limit value TSLa is reached, then the control device controls 30 via a control line 38 an alarm device 50 on, which emits an alarm signal. This may be, for example, an optical or audible alarm signal. Preferably, the alarm device is located 50 as shown in the process control room 100 the plant. As an optical signal, for example, a flashing character on the screen 40 conceivable. Thus, the operator is given the opportunity to investigate the cause of the faulty closing of the valve V2 and to take measures that allow opening of the valve V2.

When the second temperature limit value TSLL is reached, the control device controls 30 over the control line 36 the valve V1 to close this. This results in a further supply of cold fluid F1 in the heat exchanger block 2 prevented.

For the strength of the heat exchanger 1 Critical local temperature stresses can thus be prevented in a malfunction in which the valve V2 closes suddenly due to an error.

Notwithstanding the present example, alternatively or additionally, temperature limits for the measuring points 23 and 25 in the control device 30 deposited and used for monitoring.

Scenario 3: Safety monitoring during commissioning of the plate heat exchanger 1

The control device 30 periodically calculates temperature difference values ΔT12 = T1 - T2 and ΔT23 = T2 - T3 and compares them with temperature difference thresholds ΔT12max and ΔT23max stored in the controller 30 are deposited. These temperature difference limits are also from a local strength calculation for the heat exchanger block 2 receive. For example, ΔT12max and ΔT23max may be 20 K (Kelvin). If these are exceeded, the control device controls 30 the valves V1 and / or V2 to cause by appropriate valve positions that the above temperature differences are kept smaller than 20 K.

This control allows critical local temperature stresses in the heat exchanger block 2 during commissioning of the plate heat exchanger 1 be prevented.

Deviating from this, it is also possible for the above temperature difference values in the control device 30 Alarm values are stored. Before the automatic intervention of the controller 30 in the valve positions, the operator is given the opportunity to return by manually adjusting the valves V1 and V2, the temperature difference values in the predetermined limits. In general, only the output of alarm signals by the alarm device 50 when the temperature difference limits are exceeded. The valves V1 and V2 must then be manually adjusted during commissioning in order to return the temperature values to uncritical ranges. LIST OF REFERENCE NUMBERS 1 Plate heat exchangers 2 heat exchanger coil 3 Divider 4 Heat exchange profile (Fin) 5 lateral outer wall of the block 2 6 End bar (side bar) 7 cover B Width of the heat exchange profiles T Depth of block 2 9 Entry opening for F1 10 Entry opening for F2 12 . 13 . 14 . 15 Essay header 16 Support 18 . 19 supply 20 . 21 derivation F1 first fluid flow F2 second fluid stream V1 Valve V2 Valve 23 . 24 . 25 Temperature measuring point T1 . T2 . T3 temperatures 30 control device 33 . 34 . 35 data line 36 . 37 . 38 control line 40 display unit 41 data line 50 alarm device 100 process control station

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1798508 A1 [0006, 0036]

Claims (11)

Method for safety-related monitoring of the operation of a thermally loaded apparatus ( 1 ), in particular a heat exchanger ( 1 ) or a chemical reactor, in a process engineering or chemical plant, in particular for controlling safety measures, comprising the following steps: (a) measuring at least one temperature (T1, T2, T3) at at least one local location ( 23 . 24 . 25 ) within the apparatus or on an external wall ( 5 ) of the apparatus ( 1 ); (b) comparing the measured temperature (T1, T2, T3) or a temperature comparison value calculated from one or more of the measured temperatures (T1, T2, T3) with one in a control device ( 30 ) temperature setpoint or temperature limit for the local location (s), the temperature setpoint or temperature limit resulting from a strength calculation for the local location (s); (c) driving or not driving a circuit (V1; V2; 50 ), in particular an alarm device ( 50 ) or a valve (V1, V2) for controlling the volume flow of at least one of the fluid streams (F1, F2) flowing into the apparatus, as a function of the comparison. Method according to claim 1, characterized in that in step (a) at least two local locations ( 23 . 24 . 25 ) within the apparatus or on an external wall ( 5 ) of the apparatus ( 1 ) Temperatures (T1, T2, T3) are measured, in step (b) a difference value of both temperatures is formed, which is compared with a temperature difference limit value, from a strength calculation for the local points ( 23 . 24 . 25 ) results. A method according to claim 1 or 2, characterized in that in step (b) for at least one local location, the slope of the temperature curve is calculated and compared with a temperature slope limit or temperature gradient setpoint for the local location. Method according to one of the preceding claims, characterized in that upon reaching a first temperature limit value, an alarm device ( 50 ) is triggered in step (c), which outputs an alarm signal, in particular an optical and / or acoustic alarm signal. Method according to one of the preceding claims, characterized in that in the apparatus ( 1 ) at least two fluid streams (F1, F2) for indirect heat exchange with each other. Method according to one of the preceding claims, characterized in that when a second temperature limit value is reached, a valve (V1, V2) for controlling the volume flow of at least one fluid flow (F1, F2) flowing into the apparatus is activated, in particular closed. Method according to one of the preceding claims, characterized in that in step (c) by controlling at least one valve (V1, V2), which serves to control the volume flow of at least one fluid stream (F1, F2) flowing into the apparatus, the temperature (T1 , T2, T3) at the local location (s) or the calculated temperature comparison value is maintained at a predetermined setpoint or below or above a predetermined temperature limit for the local location (s). Safety device for a process-engineering or chemical plant, in particular for carrying out a method according to one of the preceding claims, comprising: a) at least one first temperature sensor at at least one local location ( 23 . 24 . 25 ) within the apparatus or on an external wall ( 5 ) of the apparatus ( 1 ), b) a control device ( 30 ), in which at least one temperature limit value or at least one temperature setpoint is stored, which is determined from a local strength calculation for the local location (s) ( 23 . 24 . 25 ) and c) an alarm device ( 50 ) for outputting an alarm and / or a circuit (V1, V2) for controlling the temperature (V1, V2) at the local location (s) (n) 23 . 24 . 25 ), in particular a valve (V1, V2) for controlling the volume flow (F1, F2) of at least one fluid stream flowing into the apparatus. Use of a safety device according to claim 8 for a heat exchanger ( 1 ), in particular a plate heat exchanger ( 1 ) or a wound heat exchanger as an apparatus ( 1 ). Use of a safety device according to claim 8 for a chemical reactor as an apparatus ( 1 ) in which an exothermic chemical reaction takes place and the heat of reaction is removed by indirect heat exchange with a fluid flowing into the reactor. Use of a safety device according to claim 8 in a plant for the liquefaction of natural gas, for cryogenic air separation or for the production of olefins, in which the apparatus ( 1 ) a heat exchanger ( 1 ).

Images