EP4088077A1 - Verfahren und vorrichtung zur ermittlung von fouling bei einem wärmetauscher - Google Patents
Verfahren und vorrichtung zur ermittlung von fouling bei einem wärmetauscherInfo
- Publication number
- EP4088077A1 EP4088077A1 EP21711796.9A EP21711796A EP4088077A1 EP 4088077 A1 EP4088077 A1 EP 4088077A1 EP 21711796 A EP21711796 A EP 21711796A EP 4088077 A1 EP4088077 A1 EP 4088077A1
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- European Patent Office
- Prior art keywords
- variable
- medium
- heat exchanger
- value
- fouling
- Prior art date
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- Granted
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
- F28G15/00—Details
- F28G15/003—Control arrangements
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
- F22B37/56—Boiler cleaning control devices, e.g. for ascertaining proper duration of boiler blow-down
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F2200/00—Prediction; Simulation; Testing
Definitions
- the invention relates to a method and a device for determining fouling in a heat exchanger according to patent claims 1 and 2 and patent claims 14 and 15, respectively.
- Heat exchangers are technical devices that are used to heat or cool a medium. For this purpose, heat is transferred from a warmer first medium to a colder second medium. Depending on the design, heat exchangers differ in their functional principle. The most common designs are classified into one of the three functional groups of co-current, counter-current or cross-current heat exchangers.
- the medium to be heated or cooled is often referred to as the “product medium” and the heating or cooling medium is often referred to as the “service medium”.
- the service medium can be, for example, heating steam or cooling water.
- the service medium usually flows either through a line arrangement which is arranged within the product medium, or flows around a line arrangement through which the product medium flows.
- the first and the second medium are passed through the heat exchanger, the two media usually flowing past one another separated by a wall and the heat of the warmer medium being given off to the colder medium through the wall.
- a central problem with heat exchangers is so-called "fouling", in which deposits or deposits form on the inner walls of the heat exchanger.
- the reasons for the formation of such deposits can be physical, chemical or biological in nature In many cases, for example due to the given product-related framework conditions, cannot be prevented.
- the coverings inhibit the transfer of heat between the media and thereby reduce the efficiency of the heat exchanger. Once a certain degree of pollution has been reached, chemical or mechanical cleaning or, if necessary, even the exchange of the heat exchanger is necessary. This problem is particularly pronounced in large industrial heat exchangers that are used in process plants (i.e. plants in the chemical, petrochemical, glass, paper, metal production or cement industries) or in power plants and there usually require a heat transfer capacity of more than 100 kW are designed.
- a temperature control loop is able to compensate for the effects of the contamination up to a certain degree, so that the contamination is not immediately recognizable from the initial temperature of the product medium. Because of this ignorance, it is often not possible, please include to clean or replace the heat exchanger as required.
- a method for monitoring the effectiveness of a heat exchanger with regard to fouling in which a current heat flow z) R of the product medium or Qs of the service medium is detected and compared with at least one reference heat flow QRef, the corresponds to a predetermined degree of pollution, for example the degree of pollution zero and a maximum permissible degree of pollution, of the heat exchanger.
- the respective reference heat flow Q Ref is determined as a function of the current working point of the heat exchanger from a map previously created and stored with the help of a simulation program for different working points, the working point of the heat exchanger being determined by the flow rates F P , F s of both media and their Temperatures T P; On , T S On when entering the heat exchanger is determined.
- the operating point dependency of the amount of heat that can be transferred can be calculated in advance, for example at several hundred support points, without having to carry out correspondingly time-consuming measurements on the real system.
- a method for monitoring a heat exchanger is known from WO 2019/001683 A1, in which the flow rates, inlet temperatures and outlet temperatures of the service and product medium represent process variables of which the product side tig at least one process variable is variable and on the service side the inlet temperature is fixed and the other process variables are variable.
- it is planned to measure the variable process variable (s) of the product medium and the flow of the service medium and, from the measured values obtained in a reference state of the heat exchanger, a map for the mutual dependency the variable process variable (s) of the product medium and the flow rate of the service medium to be determined and saved.
- a distance between the measured value tuple formed by them and the map is determined as a measure of a deviation of the current state of the heat exchanger from the reference state.
- a current K value is determined for each heating surface from a calculated heat output, a lo garithmic temperature difference and the size of the heating surface.
- the reference values Kref are stored in a memory as a function of the load and possibly as a function of the fuel.
- the reference values Kref can be corrected with correction factors in accordance with some current state variables. For example, a correction is made according to the steam speed. However, it remains open how the reference values are obtained.
- a so-called "heating surface value FV" is defined as a measure of heating surface contamination. This is defined as the ratio of an actual evaluation factor fist to a basic evaluation factor fBasis.
- the actual evaluation factor fist is the ratio of a "measured” heat transfer coefficient Kist to a theoretical heat transfer coefficient K theory.
- the "measured” heat transfer coefficient Kist is determined on the basis of the media temperature and the size of the heating surface.
- the theoretical heat transfer coefficient KTheory is determined, among other things, on the basis of the geometric data such as pipe dimensions, width and length division, etc. of the heating surface
- the calculation of the reference status includes a recalculation of the steam generator with the basic data stored in the system and some current process data, such as feed water, live steam and ZÜ parameters the process data used are not disclosed.
- DE 102016 225 528 A1 discloses a method for monitoring a state of contamination in a heat exchanger with the aid of an additional temperature sensor which is arranged in or on the heat exchanger wall.
- the temperature sensor detects an operating wall temperature of the heat exchanger.
- This operating wall temperature is calculated correctly and a deviation between the correctly calculated operating wall temperature and a reference wall temperature is determined.
- the Correction of the operating wall temperature takes into account changes in measured values that occur as a result of operating conditions deviating from reference conditions, such as deviations in the fluid temperatures or in the volume flows of the fluids.
- Operating wall temperature and reference wall temperature are values that are measured at the same point and / or specified for the same point on the heat exchanger.
- a current fouling resistance Rf can be calculated from the difference between a current heat transfer resistance l / ki St and a heat transfer resistance l / k so n, which was determined when the heat exchanger was clean:
- a value for a variable characterizing the fouling is determined from a value for a first variable influenced by the fouling and a value of a second variable, one being determined by a change in a property of the first variable and / or the second medium, in particular a flow of the first and / or the second medium through the heat exchanger, the change in the first variable caused is at least partially compensated for by the second variable.
- variable characterizing the fouling is preferably a thermal resistance or a thermal conductivity. However, it can also be a flow resistance, for example.
- the invention is based on the knowledge that level jumps in the variable characterizing the fouling can often be explained by changes in the flow rate of the first and / or the second medium. The reason is that when the flow changes, the flow rate and the type of flow can also change at the points of heat transfer from the first to the second medium. Depending on the type of flow then setting (eg laminar flow, weakly turbulent flow, strongly turbulent flow) and flow rate, changes in the value of the first variable influenced by the fouling can then occur. Even within a flow type, the mixing and thus the heat transfer can change depending on the flow rate. For example, a turbulent flow also forms laminar boundary layers at the edge areas, the size and thus influence of which depends, for example, on the flow rate or the flow speed.
- a change in the first variable caused by a change in a flow of the first and / or the second medium through the heat exchanger is at least partially compensated for by the second variable.
- a change in the flow of the first and / or second medium causes a corresponding change in the second variable, which is then used to compensate for the influence of the flow change on the first variable.
- the invention enables a reliable quantification of the fouling resistance even with a change in flow for different heat exchangers. No knowledge of material properties or structural properties of the heat exchanger is necessary.
- the invention works purely based on measurement data. Instead of just using the heat transfer resistance or the heat transfer conductivity (or the heat transfer coefficient (k-value)) or the flow resistance as an indicator for fouling, the invention uses this variable and at the same time integrates the influence of the flow dynamics of the two media on the end result .
- the fouling resistance contained therein is advantageous regardless of the operating point.
- the invention does not require any special additional measuring instruments (e.g. a temperature sensor on a heat exchanger wall), but makes do with the instrumentation usually found in heat exchangers.
- measurements of flow rates and inlet / outlet temperatures of the media can also be dispensed with, so that complete instrumentation is not even required. If individual process variables of the product medium or service medium, for example the inlet temperature, are fixed due to given framework conditions and can therefore be assumed to be unchangeable, they also do not need to be measured.
- the invention using an industrial heat exchanger as an example, a significantly better result in the determination of fouling could be achieved than with a conventional calculation.
- the results could thus help a plant operator to a significantly better assessment of the fouling resistance.
- the invention can advantageously be applied not only to the heat balances, but also to the consideration of the pressure differences and thus the flow resistances.
- a particularly good compensation for the changes in flow can be achieved if the second variable is a variable that is not influenced by the fouling.
- the first variable influenced by the fouling is a heat transfer resistance or a heat transfer coefficient (or a heat transfer coefficient, often also referred to as the "k value").
- the heat transfer resistance or the heat transfer conductivity (or the k- Value) can be obtained particularly easily from th of temperatures of the first medium and the second medium to be determined at an input and at an output of the heat exchanger.
- the k-value in theory is made up as follows: respectively.
- X w thermal conductivity of the wall (in W / mK) ai: heat transfer coefficient from the first medium to the wall (in W / m 2 K) a.2: heat transfer coefficient from the second medium to the wall (in W / m 2 K)
- Changes in the flow of the first and / or second medium through the heat exchanger can lead to changes in the flow velocity and type of flow and thus to changes in the heat transfer coefficients ai, 2.
- the fouling resistance Rf can then be calculated by
- Rf 1 / k - X.
- the second variable X is consequently a variable that is unaffected by the fouling.
- the second variable is thus preferably a measure of the heat transfer coefficient between the first medium and the wall, the thermal conductivity of the wall and the heat transfer coefficient between the second medium and the wall.
- variable influenced by the fouling is a flow resistance of the first or the second medium through the heat exchanger.
- a flow resistance can be determined particularly easily from measured values of pressures of the first medium and of the second medium at an inlet and at an outlet of the heat exchanger.
- method 1 at the time of a flow change, in particular a sudden change, the value of the second variable is changed such that the value that characterizes the fouling remains constant .
- an initial value of the first variable can be determined (or “learned”) and the second variable can be set to an initial value that corresponds to the initial value of the first variable If the value of the first variable then increases due to fouling and due to flow changes, the flow changes cause a corresponding change in the second variable, which leads to a corresponding compensation of the first variable.
- This method is particularly suitable for operation of the heat exchanger with operating phases in which the flow is constant piece by piece and then changes abruptly. For example, this corresponds to the relatively frequent case that the flow of the product medium is regulated, the setpoint values for this being given constant.
- a constant change in flow can only be processed piece by piece. However, a continuous adaptation could then take place via an interpolation between the piece-wise changes. It is advantageous that changes to the medium after cleaning have no influence on the result and no learning data is required.
- a function can be defined that assigns a value for a flow through the heat exchanger of the first and / or the second medium to a value for the second variable assigns.
- This function can be determined or "learned" in a time interval after initial start-up of the heat exchanger or after cleaning the heat exchanger from fouling.
- the function is preferably formed by a regression of measured values of the flow and associated values of the second variable in the time interval
- the regression can be, for example, a linear regression (if only the flow of one of the two media changes) or a 3D regression (if the flow of both media changes).
- This method can also take constant changes into account, is relatively resistant to deviations in normal operation and also requires several cleanings (and then several different flow changes) to "learn" the function. It also enables comparisons between the quality of cleanings.
- method 3 value ranges are defined for the flow rate, each of which has a Value is assigned for the second size.
- the assignment of the values of the second variable to the flow is advantageously determined or "learned" in a time interval after the heat exchanger has been started up for the first time or after fouling has been removed from the heat exchanger something can be filtered so that they do not change too much. It is also possible to interpolate between the different learned points instead of quantizing in order to produce a "smoother" transition.
- the time interval for defining the function or the range-wise value assignments depends on the speed of the fouling processes and can, for example, between a few hours (for fast fouling processes that e.g. lead to weekly cleaning of the heat exchanger) and a few days (in the case of slow fouling processes which, for example, lead to monthly cleaning of the heat exchanger).
- method 1 can be used and the jump height and compensation height taken into account as a new learning point in methods 2 and 3. This means that learning points are also possible in a dirty state.
- a characteristic curve for a relationship between the second variable and the flow rate of one of the two media is determined, with a characteristic curve of a mathematical derivation of the first variable according to the flow rate of the first step to determine the characteristic curve Medium is determined and, in a second step, the characteristic curve obtained in the first step is again integrated in relation to the flow of the medium.
- the basic idea for solving this problem is to estimate the derivative of the first variable according to the flow rate (e.g. (d l / k) / dF)), from which the fouling can be calculated.
- the integration of the derivative then provides the actual relationship again, whereby the absolute value is obviously lost.
- this is also not necessary in the application, since only relative changes in flow have to be compensated.
- a first characteristic curve for a relationship between the second variable and the flow of the first medium and a second characteristic curve for a relationship between the second variable and the flow of the second medium are determined at the same time of the characteristic curves in a first step for each of the two media a characteristic curve of a mathematical derivation of the first variable according to the flow of the respective medium is determined and in a second step the characteristic curves obtained in the first step again in relation to the flow of the respective medium to get integrated.
- the two last-mentioned embodiments of the method have the advantage that one does not have to rely on learning the characteristic curves after cleaning, since the fouling effect is largely compensated for by the formation of a derivative.
- a device according to the invention for performing the method according to the invention described above comprises
- an evaluation device which is set up to determine a value for a variable characterizing the fouling from a value for a first variable influenced by the fouling and a value of a second variable, one due to a change a flow of the first medium and / or the second medium through the heat exchanger caused change of the first variable is at least partially compensated for by the second variable.
- the first variable can be a heat transfer resistance or a heat transfer conductivity (or a heat transfer coefficient (k value)), the first variable and the second variable from several of the following measured variables
- Flow rates of the first medium and the second medium through the heat exchanger is determined and without using material properties of the first medium and the second medium and structural properties of the heat exchanger when determining the first and the second variable.
- the first variable can also be a flow resistance, the first variable and the second variable consisting of several of the following measurands
- Flow rates of the first medium and the second medium through the heat exchanger is determined and without using material properties of the first medium and the second medium and structural properties of the heat exchanger when determining the first and the second variable.
- the “derived variables” can be, for example, statistical variables such as mean values, minima, maxima of measured values.
- a computer program according to the invention comprises instructions which, when the program is executed on a computer, cause the computer to carry out a method according to the invention as described above.
- a corresponding computer program product comprises a storage medium on which a program is stored with instructions which, when the program is executed on a computer, cause the computer to carry out a method according to the invention as described above.
- FIG. 1 shows a block diagram of a heat exchanger and a
- FIG. 2 shows a time profile of a standardized k value for an industrial heat exchanger according to the prior art
- 3 shows a basic time course of the fouling resistance without a change in flow rate when calculating according to method 1 of the invention
- FIG. 5 shows a time profile of the 1 / k value for the industrial heat exchanger according to FIG. 1 with a calculation according to method 1 of the invention
- FIG. 6 shows an application of a linear regression using the example of the industrial heat exchanger from FIG. 2,
- FIG. 7 shows a time profile of the fouling resistance Rf for the industrial heat exchanger from FIG. 2 with a calculation according to method 2 of the invention
- FIG. 8 shows a time profile of the fouling resistance Rf for the industrial heat exchanger from FIG. 2 with a calculation according to method 3 of the invention
- FIG. 10 shows a time profile of the flow rates of a service medium and a product medium for an industrial heat exchanger for fouling determination according to a further embodiment of the invention
- FIG. 11 shows a time profile of temperatures of the service medium and the product medium in relation to the flow rates according to FIG. 10,
- FIG. 12 shows a time course of a variable that characterizes the fouling determined according to method 5 of the invention from the flow rates and temperatures according to FIG. 10 and FIG. 11,
- FIG. 13 shows a time profile of the flow rates of a service medium and a product medium for an industrial heat exchanger for fouling determination according to a further embodiment of the invention
- FIG. 14 shows a time profile of temperatures of the service medium and the product medium in relation to the flow rates according to FIG. 13, 15 shows a time course of a variable that characterizes the fouling determined according to method 6 of the invention from the flow rates and temperatures according to FIG. 13 and FIG. 14,
- FIG. 16 shows a block diagram of a heat exchanger and a cloud-based device for determining fouling in a heat exchanger.
- the heat exchanger 1 shows an example and a simplified representation of a heat exchanger 1 for the transfer of heat or cold from a service medium S to a product medium P.
- the heat exchanger 1 is exemplified as a counterflow heat exchanger, but other types of heat exchangers are also possible.
- the product medium P flows through a line 2.
- the flow rate F P (or the flow rate or the volume flow) of the product medium and its temperature T P in before it enters the are measured by means of a flow sensor 4 and a temperature sensor 5 Heat exchanger 1 measured.
- a further temperature sensor 6 arranged downstream of the heat exchanger 1 in the flow direction measures the temperature T PAus of the product medium P emerging from the heat exchanger 1.
- the product medium P is heated or cooled by means of a service medium S, which is supplied to the heat exchanger 1 from a heating or coolant supply.
- a service medium S which is supplied to the heat exchanger 1 from a heating or coolant supply.
- the flow rate F s (or the flow rate or the volume flow) of the service medium and its temperature T S A are measured by means of a flow sensor 7 and a temperature sensor 8 before it enters the heat exchanger 1.
- a further temperature sensor 9 arranged downstream of the heat exchanger 1 in the flow direction measures the temperature T s , Aus of the service medium S emerging from the heat exchanger 1.
- the heat flow can also be calculated using the following formula, which results from the mechanical structure of the heat exchanger:
- AT m mean logarithmic temperature difference ⁇ : heat flow.
- the logarithmic mean temperature difference ATm is defi ned as ⁇ where DTA stands for the temperature difference on the inlet side (from the point of view of the product medium) and DTB for that on the outlet side.
- the current fouling resistance can be calculated from the difference between the current thermal resistance 1 / kist and the thermal resistance 1 / ksoii, which was determined in the clean state.
- the k-value can be calculated with the formula
- FIG. 2 shows, by way of example, a typical profile of the 1 / k value over time t for an industrial heat exchanger.
- FIG. 2 shows a value 1 / k ′ related to the initial value ko.
- Vertical lines show the cleaning times. In some areas, a decrease of 1 / k 'caused by fouling can be seen here. However, there are level jumps at the points marked with an arrow, which make an accurate evaluation of the Fou ling resistance difficult.
- the determination of the fouling resistance can be carried out more precisely in that flow changes in the product and / or service medium are also taken into account in the evaluation.
- the k-value is composed as follows: respectively.
- the fouling resistance R f can then be calculated by
- R f 1 / k - X.
- X a second quantity that is not affected by the fouling.
- the second variable X is thus a measure of the heat transfer coefficient between the first medium and the wall, the thermal conductivity of the wall and the heat transfer coefficients between the second medium and the wall.
- changes in the first variable here the calculated k value, caused by changes in the flow rate, are at least partially compensated for with the aid of a second variable, here a value of the variable X.
- the fouling resistance does not fall or rise significantly without a particular reason (e.g. cleaning) in normal operation.
- X remains constant. Any change in the 1 / k value is therefore attributable to fouling.
- the value X is constant and leads to a constant difference between 1 / k and R f .
- a mean value for an interval from to to to + x can now be used for 1 / k.
- the fouling resistance is then calculated again using Rf 1 / knew Xnew.
- FIG 6 shows an example of an application of the linear regres sion the example of the industrial heat exchanger of FIG 2.
- the function f to define the heat exchanger for a number average flow values F P were after cleaning side of the product the associated X values are determined (marked with in FIG. 6). Flow changes within this interval are taken into account.
- X f (F p) , where the function f results from the linear regression of F p and X.
- the function f can, for example, by a linear regression (if only the flow rate of one of the two media changes, see FIG 6) or a 3D regression (if the flow rates of both media change) of measured values of flow rates and associated values of the second Size can be formed in the time interval after initial start-up or cleaning.
- This method can also take constant changes into account, is relatively resistant to deviations in normal operation, but also requires several cleanings (and then several different flows) to "learn" the function f. It also enables comparisons between the quality of cleanings.
- the X values learned after initial commissioning or cleaning can be used to create value ranges for the flow rate.
- a learned X value is assigned to each flow value within such a range. This X value can be filtered a little over time so that the transitions between two X values do not become too abrupt.
- the assignment of the values of the second variable to the flow rates is advantageous here in a time interval after a ner initial start-up of the heat exchanger or after cleaning the heat exchanger from fouling.
- the transitions between values of the second variable can be filtered a little at the range limits so that they do not change too much.
- quantizing it is also possible to interpolate between the various learned points in order to create a "smoother" transition.
- a so-called "support point method” represents an optimization possibility. This method also represents a possibility of how the analysis of a relationship between flow rate and reference value could be implemented Depending on the flow rate, boundary conditions for the later characteristic curve or function could already be found, such as the monotony of the curve.
- the first values for the analysis are obtained and drawn in in a clean state after cleaning.
- New values are added during the term. These are weighted with the previous values and summarized in a certain range and the characteristic curve is updated.
- the weighting factor can be the number of previous points in an area or the current fouling resistance.
- the fouling resistance or the X value for the heat exchanger could first be determined using method 1 and then in the medium term the X value can be calculated using a ratio of both methods (depending, for example, on the deviation between methods 1 and 2 , the variance of method 2 or the number of data points for method 2). In the long term, only method 2 should suffice.
- a characteristic curve for a relationship between the second variable and the flow rate of one of the two media is determined, with a characteristic curve of a mathematical derivation of the first variable according to the flow rate to determine the characteristic curve in a first step of the medium is determined and, in a second step, the characteristic curve obtained in the first step is again integrated in relation to the flow of the medium.
- the basic idea for solving this problem is to estimate the derivative of the first variable according to the flow rate (e.g. (d l / k) / dF)), from which the fouling can be calculated.
- the integration of the derivative then provides the actual relationship again, whereby the absolute value is obviously lost.
- this is also not necessary in the application, since only relative changes in flow have to be compensated.
- the absolute value is advantageously irrelevant, so that no initial value has to be taken into account in the integration.
- a special feature of this method is that the actual task of determining fouling takes a back seat and the effect of fouling is being compensated in order to estimate the X-F characteristic. Only then is the fouling determined using the characteristic curve from 1 / k.
- a characteristic curve can advantageously be easily implemented so that nothing stands in the way of an online evaluation.
- FIGS. 10 to 12 show a simulation of an industrial heat exchanger with a variation of a flow rate. 10 shows a time profile of (simulated) measured values of the flow rate F P of the product medium and the flow rate F s of the service medium through the heat exchanger.
- FIG. 11 shows the associated (simulated) measured values for the temperature T P Ein of the product medium at the inlet and the temperature T PAus of the product medium at the outlet of the heat exchanger.
- (simulated) measured values of the temperature T S in of the service medium at the inlet and the temperature T s , out of the service medium at the outlet of the heat exchanger are shown.
- FIG. 12 shows the associated calculated relative values for 1 / k and the fouling resistance R f .
- the 1 / k value shows a significant dependency on changes in flow, regardless of the side of the heat exchanger. An overlaid trend can still be seen in the idealized data. Depending on the severity of the fouling, however, no reliable statement can be derived from the 1 / k value alone.
- a first characteristic curve for a relationship between the second variable and the flow of the first medium and a second characteristic curve for a relationship between the second variable and the flow of the second medium are determined at the same time Determination of the characteristic
- a characteristic curve of a mathematical derivation of the first variable according to the flow of the respective medium is determined for each of the two media and in a second step the characteristic curves obtained in the first step are again related to the flow of the be integrated in the respective medium.
- the fouling i can be estimated by first determining - and using the characteristics the fouling is calculated.
- the absolute values of the characteristics are unknown due to the integration. Because of the simpler parameterization, the modeling is only done qualitatively anyway, i.e. 1 / k is determined without exact material data or properties of the heat exchanger. Only relative changes in the k-value can thus be calculated. However, the specific characteristics can be used precisely for relative changes in the flow rates.
- FIGS. 13-15 show a simulation of an industrial heat exchanger with variation of the flow rates.
- FIG. 13 shows a time profile of (simulated) measured values of the flow rate F P of the product medium and the flow rate F s of the service medium through the heat exchanger.
- FIG. 14 shows the associated (simulated) measured values for the temperature T P Ein of the product medium at the inlet and the temperature T PAus of the product medium at the outlet of the heat exchanger.
- (simulated) measured values of the temperature T S In of the service medium at the inlet and the temperature T s , Out of the service medium at the outlet of the heat exchanger are shown.
- FIG. 15 shows the relative values calculated therefrom for 1 / k and the fouling resistance Rf.
- the 1 / k value shows a significant dependency on changes in flow, regardless of which side of the heat exchanger. An overlaid trend can still be seen in the idealized data. Depending on the severity of the fouling, however, no reliable statement can be derived from the 1 / k value alone. Using the characteristic curves and compensating for the associated flow dependencies results in the estimated Fouling curve Rf. Except for the measurement noise, a linear trend can be identified. The fouling can thus be determined very reliably, even if both flow rates change at the same time.
- the methods enable a reliable quantification of the fouling resistance even if the flow rate changes for different heat exchangers. No knowledge of material properties or structural properties of the heat exchanger is necessary. The methods all work purely based on data. So far, only the pure k-value has been used as an indicator for fouling. These methods use this variable and at the same time incorporate the influence of the flow dynamics of the two media on the end result.
- the method according to the invention can be provided as a stand-alone application in a process plant or can be integrated into a process control system of a process plant. It can also be provided in a local or remote computer system ("cloud"), e.g. by a service provider as "software as a service”.
- cloud e.g. by a service provider as "software as a service”.
- a Vorrich device 10 according to the invention shown by way of example in FIG. 1 for determining fouling comprises
- An evaluation device 30 which is set up to determine and output a value for the fouling resistance Rf from these measured values by means of a method described above. Additionally or alternatively, the evaluation device can also function as a monitoring device: it can monitor the determined fouling resistance for exceeding a threshold value and output a signal if it is exceeded, which signals, for example, a need for cleaning.
- the evaluation device 30 comprises a processor unit 31, a memory 32 for storing the received measurement data, and a memory 33 in which a program 34 with instructions is stored when they are executed by means of the Processor unit 31 one of the methods described above is carried out.
- the processor unit 31 stores the measured values M received from the device 20 in the memory 32.
- the device 10 shown in FIG. 1 can, for example, be provided as a stand-alone application in a process plant or can be integrated into a process control system of a process plant.
- a device 100 shown in FIG. 16 for determining fouling can be provided by a local or remote computer system ("cloud"), e.g. in order to offer the determination of fouling by a service provider as "software as a service”.
- the receiving device 20 is located on site in the process plant of the heat exchanger 1 and the evaluation device 30 is located on a local or remote computer system ("cloud").
- the receiving device 20 stores the received measured values in a memory 21 and sends the measured values M (or variables derived therefrom) to the evaluation device 30 (e.g. at regular time intervals, event-controlled or upon request by the evaluation device 30) by means of a transmission device 22, e.g. via the Internet or an intranet.
- the evaluation device 30 comprises a processor unit 31, a memory 32 for storing the received measurement data, and a memory 33 in which a program 34 with instructions Solutions is stored, when executed by means of the processor unit 31, one of the methods described above is carried out.
- the processor unit 31 stores the measured values M received from the device 20 via an interface 36 in the memory 32, as well as, if necessary, for further input variables that are received via a separate interface 37.
- the values determined with the program 34 for the fouling resistance R f and / or a signal which signals the need for cleaning are output via an interface 38.
- the interfaces 36, 37 and 38 can also be provided by a single common interface, for example to the intranet or an intranet.
Abstract
Description
Claims
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EP20161837 | 2020-03-09 | ||
PCT/EP2021/055563 WO2021180581A1 (de) | 2020-03-09 | 2021-03-05 | Verfahren und vorrichtung zur ermittlung von fouling bei einem wärmetauscher |
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EP4088077A1 true EP4088077A1 (de) | 2022-11-16 |
EP4088077C0 EP4088077C0 (de) | 2023-12-27 |
EP4088077B1 EP4088077B1 (de) | 2023-12-27 |
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EP21711796.9A Active EP4088077B1 (de) | 2020-03-09 | 2021-03-05 | Verfahren und vorrichtung zur ermittlung von fouling bei einem wärmetauscher |
Country Status (4)
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US (1) | US20230122608A1 (de) |
EP (1) | EP4088077B1 (de) |
CN (1) | CN115280094A (de) |
WO (1) | WO2021180581A1 (de) |
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JPS5919273B2 (ja) | 1979-12-05 | 1984-05-04 | 株式会社日立製作所 | 復水器性能監視方法 |
EP0470676A3 (en) | 1990-08-09 | 1992-09-16 | Riccius + Stroschen Gmbh | Procedure to determine the state of clogging of heat conducting tubes |
DE19502096A1 (de) | 1995-01-24 | 1996-07-25 | Bergemann Gmbh | Verfahren und Vorrichtung zur Steuerung von Rußbläsern in einer Kesselanlage |
DE102005055333B4 (de) * | 2005-11-21 | 2009-01-02 | Würsig, Gerd-Michael, Dr. | Verfahren zur Leistungsbewertung von Wärmetauschern |
EP2128551A1 (de) | 2008-05-29 | 2009-12-02 | Siemens Aktiengesellschaft | Überwachung von Wärmetauschern in Prozessleitsystemen |
DE102016225528A1 (de) | 2016-12-20 | 2018-06-21 | Robert Bosch Gmbh | Verfahren und Vorrichtung zur Überwachung eines Verschmutzungszustands bei einem Wärmetauscher |
WO2019001683A1 (de) | 2017-06-26 | 2019-01-03 | Siemens Aktiengesellschaft | Verfahren und einrichtung zur überwachung eines wärmetauschers |
-
2021
- 2021-03-05 EP EP21711796.9A patent/EP4088077B1/de active Active
- 2021-03-05 CN CN202180020015.2A patent/CN115280094A/zh active Pending
- 2021-03-05 US US17/910,259 patent/US20230122608A1/en active Pending
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CN115280094A (zh) | 2022-11-01 |
WO2021180581A1 (de) | 2021-09-16 |
EP4088077C0 (de) | 2023-12-27 |
EP4088077B1 (de) | 2023-12-27 |
US20230122608A1 (en) | 2023-04-20 |
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