Method for cleaning a pressure-resistant boiler with pressure pulses, and device therefor

Abstract

A method for cleaning a pressure-resistant boiler region (10) with pressure pulses (21), which are produced by a cleaning device (20) and are introduced into the boiler (10) via an outlet opening (22) assigned to the cleaning device (20), wherein, using a control unit (30), a pressure pulse is emitted by the cleaning device (20) into the boiler region (10) at predetermined cleaning intervals to produce pressure pulses, is characterized in that a measured value characterizing the degree of soiling of the boiler is picked up by a sensor (40) and is compared with a predetermined first threshold value, wherein, depending on the correlation of the measured value with the degree of soiling, the cleaning interval is set to a shorter cleaning interval and / or the cleaning energy is set to a higher cleaning energy if the measured value is above or below the first threshold value.

Description

[0001] TITLE

[0002] Method for cleaning a pressure-resistant boiler using pressure pulses and device therefor

[0003] TECHNICAL FIELD

[0004] The present invention relates to a method for cleaning a pressure-resistant boiler with pressure pulses generated by a cleaning device, which are guided into the boiler via a discharge opening associated with the cleaning device.

[0005] STATE OF THE ART

[0006] A variety of cleaning devices are known from the prior art for introducing pressure pulses into a boiler to be cleaned. These cleaning devices are sometimes also described as devices for generating explosions, as in WO 2010 / 025574 A2, or as devices for generating high-amplitude pressure waves, as in WO 2019 / 185736 A1 by the applicant. In other words, these devices can also be referred to as devices for generating pressure pulses generated by deflagration or isochoric combustion. Pressure pulses can also be referred to as sound pulses.

[0007] In general, this involves the removal of fly ash from heat exchanger surfaces exposed to flue gases, thus affecting all combustion plants that operate with fly ash-forming fuels. These include, in particular, waste incineration plants, biomass boilers, coal-fired power plants, etc.

[0008] The cleaning devices are designed to clean a specific area of ​​the boiler around the point where the pressure waves are introduced. The cleaning devices are automatically activated at predetermined intervals in agreement with the operators of the boiler systems, e.g., waste incineration plants, to clean the boilers. The intervals are determined based on the plant operators' experience and are designed to prevent excessive contamination of the boiler system during continuous operation. Such periodic cleaning operations are carried out, for example, with a time interval of between two cleanings, which is often between one and two hours.

[0009] It is also known to trigger a cleaning device only when certain limit values ​​are reached (flue gas temperatures, pressure losses).

[0010] This conventional cleaning method returns the system or the affected system component to a certain baseline state, from which the cleaning state is then reached again after a certain period of time, either because the time interval has been reached or a limit value has been reached. Thus, with the current technology, pressure wave cleaning is performed regularly every one to two hours, and then additional manual cleaning is performed using other cleaning methods if this interval cannot or should not be shortened further, depending on, for example, pressure loss or flue gas temperatures as measured values.

[0011] DE 10 2011 108327 A1 describes a method for increasing the efficiency of a waste incineration plant with a flue gas outlet for flue gas and a heat exchanger wall that transfers heat to a heat transfer medium. This wall's function is impaired by deposits during operation of the incineration plant and must therefore be cleaned at predefined intervals using a cleaning medium from a cleaning device. The time intervals are controlled based on heat flow measurements on the heat exchanger wall carried out with heat flow sensors and / or the resulting temporal change in the heat flow through the heat exchanger wall. Cleaning is only triggered whenif a first predeterminable threshold value of the heat flow is undershot and at the same time at least one of the following conditions is met: the temporal change in the heat flow falls below a second predeterminable threshold value; the difference to a heat flow measured as a reference on the heat exchanger wall exceeds a predeterminable difference value; the flue gas temperature exceeds a previously determined and stored empirical value, which was determined for similar operating conditions of the combustion plant after a previous cleaning of the heat exchanger wall, by a predeterminable amount; a predeterminable minimum time has elapsed since the last cleaning,and / or the incineration plant has been in a steady-state operating state for a predefined time interval. DE 10 2012 014271 A1 discloses a method for controlling the use of steam- and / or water-operated cleaning devices during the operation of a steam generator. This method includes monitoring the steam generator's state variables that allow direct or indirect conclusions to be drawn about the effectiveness and / or the contamination level of the steam generator's heating surfaces, creating an effectiveness forecast based on the measured and / or determined state variables, and determining an optimal cleaning time as a function of the steam generator's effectiveness forecast.Creating a load forecast as a function of the electricity demand and / or heat demand and postponing or suppressing the cleaning time and / or shortening or extending the cleaning cycle and / or intensifying or reducing the cleaning intensity, provided that a specified minimum effectiveness of the heating surfaces is not undercut and / or a specified maximum permissible contamination of the heating surfaces is not exceeded.

[0012] US 2015 / 007782 A1 discloses systems and methods for detecting and monitoring soot and clinker formation in coal-fired power plants, disclosing the early detection of soot and hard sinter formation and the initiation of corrective actions for soot cleaning through automatic cleaning events based on the observed heat transfer efficiencies in the boiler area of ​​the power plant.

[0013] US 2004 / 244729 A1 describes a controller for determining and adjusting system parameters, including cleanliness levels or sootblower operating settings, that are useful for maintaining the cleanliness of a fossil fuel boiler at an efficient level. The controller uses inputs from the actual performance or condition of the boiler to adjust the parameters. The controller works in conjunction with a sootblower optimization system that controls the actual sootblower settings. The controller can coordinate cleanliness settings for multiple sootblowers and / or for multiple heating zones in the boiler.

[0014] PRESENTATION OF THE INVENTION

[0015] Based on this prior art, the object of the invention is to provide a cleaning method and a control system for a cleaning device with which the cleaning can be made more energetically and economically efficient.

[0016] Such a cleaning method is set out in claim 1.

[0017] With the cleaning method according to the invention, the plant or the affected plant section is not periodically returned to a basic state in the sense of the cleanest possible condition by means of maximum cleaning, but only a partial cleaning is carried out. The partial cleaning, which returns the corresponding boiler section to a basic level of contamination using the predetermined parameters of cleaning energy and cleaning interval, is controlled via threshold values ​​with which the cleaning energy and / or the cleaning interval are set. In addition to reducing corrosion, this results in more uniform operation of the boiler plant. In the industrial sector, more uniform operation has the major advantage that it is possible to operate closer to performance limits, which leads to higher throughput because, for example, maximum boiler temperatures are not reached as quickly.

[0018] In a cleaning method having the features of the preamble of claim 1, a sensor continuously or discontinuously records a measured value indicative of the degree of contamination of the boiler, which is compared with a predetermined first threshold value. Depending on the correlation of the measured value with the degree of contamination, if the first threshold value is exceeded or undershot, the cleaning interval is adjusted to a shorter cleaning interval or the cleaning energy is adjusted to a higher cleaning energy. The measured value can also be a value calculated from measured values. For example, a pressure loss is calculated from two pressure measurements. In such a case, the sensor is the combination of one or more measuring sensors and the calculation and output unit for the calculated value.

[0019] The sensor's measured values ​​are usually recorded continuously. The evaluation of the measured values, which produces the characteristic value, occurs, for example, towards the end of the previously defined cleaning interval to set a new threshold value, a shorter cleaning interval, or a higher cleaning energy.

[0020] The cleaning interval is the time interval between a previous cleaning process and the one immediately following it. During the cleaning interval, measured values ​​can be recorded. A measured value interval exists between two measured value recordings. An evaluation interval then ends before a cleaning process is triggered. This previously defined evaluation interval is used to set a new cleaning intensity, if necessary. For example, the last measured value recorded or an average value across several measured values ​​recorded over all or part of the evaluation interval can be used. Instead of using just one measured value, the measured value used for comparison with the threshold value, which indicates the degree of contamination of the boiler, can also be determined from several measured values ​​recorded by the sensor, in particular as the mean, highest or lowest value of these measured values.

[0021] If the cleaning interval is set to an even shorter cleaning interval and / or the cleaning energy is set to an even higher cleaning energy each time the first threshold value is exceeded or undershot, it is possible to react more quickly to increasing or decreasing contamination.

[0022] A second threshold value can also be provided which has a lower value than the first threshold value, whereby, depending on the correlation of the measured value with the degree of contamination, if the second threshold value is undershot or exceeded, the cleaning interval is set to a longer cleaning interval and / or the cleaning energy is set to a lower cleaning energy, i.e. the cleaning intensity is regulated to a lower level. The aim of using two threshold values ​​is essentially to set the cleaning intensity to a level that is slightly lower than the cleaning intensity in order to bring the contamination from the upper to the lower threshold value, so that an almost uniform cleaning intensity is set which, in reducing the degree of contamination in the boiler area, corresponds to the difference between the two degrees of contamination at the respective threshold values.

[0023] A cleaning intensity can be specified based on the values ​​of cleaning intervals and cleaning energy quantities. If n sensors are provided, the next higher cleaning intensity is selected (where n>=2) if the measured value of at least one of the n sensors exceeds the upper threshold of the corresponding sensor or falls below the lower threshold of the corresponding sensor. The influences of various physical parameters can be incorporated into the process.

[0024] The measured value from one of the sensors can be input to a value that defines the degree of contamination. One application is the sewage sludge co-incineration rate, which is a parameter known to the operator for the current operating state and is replaced by an input instead of a sensor measurement.

[0025] K+1 cleaning intensities can also be provided, with an i-th cleaning intensity being selected if at least one of the n sensors exceeds the i-th threshold of the corresponding sensor, but no measured value from any of the n sensors exceeds the (i-1)th threshold, where i=2 to k. If no measured value from any of the n sensors exceeds the k-th threshold of the corresponding sensor, the (k+1)th cleaning intensity is selected. The settings are then selected based on the "best" or worst measured value for the degree of contamination, allowing for faster countermeasures depending on the sensor type.

[0026] When using a measured value characterising the degree of contamination of the boiler by a sensor where a higher degree of contamination corresponds to a lower measured value, for example the k-value as explained in the description, the measured value used in the method is an inverted or negative measured value of the said sensor.

[0027] The correlation between the measured value and the degree of contamination determines what happens when the first (or a subsequent) threshold is exceeded or undershot. If the correlation is such that exceeding or falling below the threshold corresponds to a greater degree of contamination, the cleaning interval is set to a shorter interval and, simultaneously or alternatively, the cleaning energy is set to a higher energy level.

[0028] Conversely, if exceeding or falling below the threshold corresponds to a lower degree of contamination, the cleaning interval is set to a longer cleaning interval and, simultaneously or alternatively, the cleaning energy is set to a lower cleaning energy. The latter case occurs when using the k-value as explained in the following description. According to the definition here, this is an inverted or negative measured value of the sensor in question. To avoid this problem, the measured value in question, which is a positive number, can also be multiplied by -1, so that, as with other measured values, a higher value (i.e., a less negative value below zero) corresponds to greater contamination.

[0029] Further embodiments are specified in the dependent claims.

[0030] BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Preferred embodiments of the invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. In the drawings:

[0032] Fig. 1 is a schematic sectional view of a boiler with a cleaning device for carrying out a cleaning method according to an embodiment of the invention;

[0033] Fig. 2A is a graph of a measured value versus time for a prior art cleaning device;

[0034] Fig. 2B is a graph of a measured value versus time for a prior art cleaning device;

[0035] Fig. 3 is a diagram of a measured value versus time for a cleaning device according to an embodiment of the invention over several measuring time intervals;

[0036] Fig. 4 is a diagram of a measured value versus time for a cleaning device according to a further embodiment of the invention over several measuring time intervals;

[0037] Fig. 5 shows a section from Fig. 3 or Fig. 4 when executing a cleaning pulse;

[0038] Fig. 6 is a schematic flow diagram for the method according to Fig. 3; and

[0039] Fig. 7 shows a schematic flow diagram when using multiple sensors.

[0040] DESCRIPTION OF PREFERRED EMBODIMENTS Fig. 1 shows a schematic sectional view of a pass of a boiler section 10 with a cleaning device 20 for carrying out a cleaning method according to an embodiment of the invention. The two horizontal lines represent a section of the walls of the boiler section 10, with the flue gas path of this boiler region of the system being represented by the reference numeral 11. This boiler region can also be referred to as an entire pass or a region of a pass, which begins at the beginning 12 of the boiler section and continues here at the end 13 of the boiler section into another section of the boiler or another pass. In each case, it is usually one boiler region in which the cleaning device 20 exerts its cleaning effect and in which the corresponding sensors 40 are also provided.For certain operating parameters, sensors located in adjacent boiler sections can also be used to obtain a higher-level measured value. These could be pressure sensors, for example, so that a pressure change between boiler sections can be detected using the pressure sensors. The draft here is arranged horizontally; it can also be arranged vertically rising, vertically falling, or diagonally rising or falling.

[0041] The cleaning device 20 ends with a pipe area in or on the boiler wall through which the said pressure waves are introduced into the boiler area 10.

[0042] The cleaning device 20 has a known control system, as described, for example, in WO 2019 / 185736 A1. With the known control system, a cleaning process is carried out, from the supply of fuel gases to trigger the pressure waves as pressure pulses from corresponding supplies or supply lines of the cleaning device up to ignition. The time intervals for carrying out the cleaning process are predetermined by the cleaning device 20. In Fig. 1, this cleaning device 20 is connected to a control unit 30 via a connection 31. The connection 31 can be cable-based or radio-based in order to transmit control signals from the control unit 30 to the cleaning device 20 to trigger the cleaning process.

[0043] The control unit 30 comprises a microprocessor, a power supply, and a data memory for a control program for executing the cleaning method according to an embodiment of the invention. Input means such as a keyboard and output means such as screens are typically also included in the control unit 30. Furthermore, the control unit 30 can be connected to other control units of the boiler system as a whole. The control unit 30 is connected to a sensor 40 via a data line 41. Here, too, the data line 41 can be cable-based or radio-based. The sensor 40 is shown here downstream in the same train of the boiler 10. The sensor 40 can also be provided upstream in the same train or in another train upstream or downstream of the cleaning device 20.

[0044] The term "boiler area 10" can also be replaced by "system part," "boiler part," or "boiler" if the cleaning device 20 cleans only part of a boiler. In practice, a boiler can also be provided with several, such as 5 to 8, cleaning devices 20 at appropriate intervals, which includes longitudinal spacing in the longitudinal direction of the boiler 10 and / or arrangements along the circumference of the boiler 10.

[0045] Sensors 40 that can be considered in particular include: one or more flue gas temperature sensors in one or more boiler sections; in the case of multiple passes, the measured flue gas temperature can then be measured at the transition from the 1st pass to the 2nd pass or even at the last pass. one or more pressure sensors to determine pressure losses. This can be a load- and / or temperature-adjusted pressure loss, with the pressures generally being measured in different boiler sections—often in the first and last boiler section, sometimes also after each boiler section—and pressure differences or pressure losses between these measurements then being determined.several sensors to determine the heat transfer coefficient or k-value, which is measured indirectly, where the k-value = the amount of heat transferred divided by the product of the average temperature difference during heat transfer and the heat transfer area. The amount of heat transferred is usually determined from the amount of water or steam and the temperatures measured at the inlet and outlet, and the temperature difference between the water or steam side and flue gas side temperatures at the inlet and outlet. Here, a lower k-value corresponds to higher pollution, which is a reversal of the relationship to the other three measured values ​​mentioned. the sewage sludge co-incineration rate, which is calculated, for example, as the quotient of the amount of sewage sludge introduced and the amount of fuel introduced (waste, biomass, etc.).This sewage sludge co-incineration rate is not based on a sensor measurement as such, but corresponds to the input of this rate, whereby the reading of this rate is then considered as a "sensor measurement".

[0046] Fig. 2A shows a graph of a measured value 51 versus time for a cleaning device according to the prior art, in which a known maximum cleaning is performed. One possible measured value of the prior art is the flue gas temperature in the flue gas direction downstream of the affected boiler section. Fig. 2B shows a graph of a measured value 5T versus time for a cleaning device according to a different prior art. In the generally used prior art according to Fig. 2A, a measured value 51 for the flue gas temperature is determined, and a maximum value 52 is specified, which should not be exceeded during continuous operation if possible.

[0047] For all figures (Figs. 2A to 5), the sawtooth curve shown represents an idealized representation of the degree of contamination over time. In reality, this is not a monotonically increasing straight line, but rather a substantially increasing curve from a minimum value to a maximum value. It is assumed that initiating cleaning directly leads to a decrease in the degree of contamination (or the measured value representing it from a sensor). Higher levels of contamination may occur briefly in the area where contamination is being removed, which is why, among other things, the explanation in Fig. 5 indicates a suspension of the evaluation of measured values.

[0048] The process involves several types of time intervals. These include the cleaning interval 53 and the measuring interval 54. The cleaning interval 53, which in practice can be an average of one hour or eight hours, is significantly longer than the measuring interval 54, since most sensors can and do measure every second or even more frequently. The evaluation interval is then also every second, but can be longer (e.g. every minute or - if the evaluation is done manually - every few hours or once a day, etc.). The measuring interval 54 is shown schematically in Fig. 2A as being exaggeratedly long, since with a cleaning interval 53 of, for example, 8 hours, even a measuring interval 54 of 1 minute would be almost a factor of 500 shorter.

[0049] In practical operation, the cleaning interval would be adjusted at longer intervals, i.e. the operation of a device would be adjusted at longer intervals, ideally over several cleaning processes, but certainly not after one cleaning or even more frequently.

[0050] Fig. 2A shows the standard operation with a fixed cleaning interval 53 of the same length, which results in cleaning during operation regardless of whether the said maximum value of the measured value is reached or not.

[0051] Fig. 2B shows a different cleaning regime in which the maximum value 52' is set as the threshold that triggers cleaning. This results in cleaning intervals of varying lengths.

[0052] Fig. 3 shows a diagram of a measured value 61 against time for a cleaning device according to an embodiment of the invention. In this embodiment, the length of the cleaning interval is controlled. After the expiration of a first cleaning interval (here without reference symbol) at time t1, the then existing measured value is determined and compared with the first and second threshold values ​​62 and 62'. Since the measured value is less than the first threshold value 62 and greater than the second threshold value 62', the existing cleaning interval 63 is retained and set for the next cleaning interval. After the next and the next but one expiration of the cleaning interval 63, the measured value is also between the two threshold values ​​62 and 62', so that nothing changes for the next cleaning interval 63 either.Due to the "short" cleaning intervals 63, the contamination in the boiler decreases, so that for the next cleaning interval 63, at time t2, the measured value is below the second lower threshold 62'. Therefore, the cleaning interval is extended to cleaning interval 63'. The cleaning energy 64—indirectly represented by the change in the measured value—remains the same. Due to this extension of the cleaning interval 63', the measured values ​​increase at the decision time when compared with the threshold values, and at time t3, the measured value exceeds the first upper threshold 62, so that the shorter cleaning interval 63 is set again thereafter.

[0053] This control sequence is shown at an exaggerated speed to illustrate the mechanism. In variations, if the threshold value 62' is undershot twice, the cleaning interval 63 is extended a second time. Conversely, if the upper threshold value 62 is exceeded several times, the cleaning interval 63 is shortened several times.

[0054] Fig. 4 shows a graph of a measured value 61 versus time for a cleaning device according to another embodiment of the invention. In this embodiment, the cleaning energy is controlled. The process sequence and the effects on the measured values ​​in the boiler between times t1 and t2 are the same as in Fig. 3. If the measured value falls below the second threshold 62' at the time the cleaning interval 63 expires, the cleaning energy 64' is reduced.

[0055] It can be seen that after the next two cleaning intervals 63, the measured value at the decision time is still below the lower second threshold value 62'. In further embodiments, as in the embodiment according to Fig. 3, this can further reduce the cleaning energy each time the threshold value 62' is undershot. However, this leads to a greater vibration intensity of the process. Here, the cleaning energy 64' is maintained, whereby after a further four cleaning cycles at time t3' the measured value is above the first threshold value 62, and thus the cleaning energy is reset to the higher cleaning energy 64.

[0056] In other embodiments, the cleaning interval or cleaning energy is only reset after the threshold values ​​have been repeatedly exceeded or undershot. It is also possible to modify the cleaning interval and cleaning energy simultaneously or sequentially in one process, thus combining the embodiments of Figures 3 and 4.

[0057] It was mentioned above with regard to the sensor for determining the heat transfer coefficient or k-value that its measured value decreases with increasing contamination, meaning that with a decrease, the contamination of the boiler area increases. This measured value behaves in exactly the opposite way to the other measured values. This measurement can also be used in the process if, when using a measured value characterizing the degree of contamination of the boiler by a sensor 40, where a higher degree of contamination corresponds to a lower measured value, the measured value used in the process is an inverted or negative measured value of said sensor 40. The measured value can be replaced by its negative value with corresponding negative threshold values. In a simple programming implementation, the "higher" threshold values ​​of the process are replaced by "lower" threshold values ​​in order to adjust the cleaning energy accordingly.This applies to both the adjustment of the cleaning interval and the cleaning energy.

[0058] Fig. 5 shows an enlarged section of Fig. 3 or Fig. 4 when carrying out a cleaning.

[0059] Cleaning involves triggering the cleaning device with a pressure pulse or triggering a sequence of pressure pulses in quick succession. "A" pressure pulse refers to a pulse burst, which, as shown in Fig. 16 of WO 2019 / 185736 A2, may well also include oscillations of pressure changes. This requires a certain time, which is shown here as being between t11 and t12.

[0060] The above-mentioned measured values ​​collected during the measurement intervals are presented as continuous measured values. The respective "measurement curve" 61 is hypothetical and does not correspond to recorded measured values. These measured values ​​are not collected or used during a dead time 65 from immediately before t10 of a cleaning cycle until a predetermined period t13 after a cleaning cycle, as they fluctuate to a greater or lesser extent due to the operation of the cleaning cycle.

[0061] The time intervals for cleaning can be determined based on the long-term development of the measured values. These can follow the development of average values, in particular moving averages over multiple cleaning cycles. This means that a comparison is made between the threshold value for each measured value, from which the intensity level for each measured value is derived, from this the overall resulting intensity level, and finally from this the time interval via the previously defined linking of the intensity level to a time interval. If the measured values ​​are classified in the highest intensity level, a small temporal adjustment of the time interval for cleaning can be made for each further exceedance of the threshold value in subsequent measuring intervals.

[0062] Cleaning can be a single pulse, a sequence of such pressure pulses in quick succession, or a combination of single and consecutive pressure pulses. These combinations are referred to as "mixed mode." This allows the cleaning energy to be easily adjusted.

[0063] The cleaning energy applied can also be adjusted by increasing or decreasing the amount of fuel required to generate the pressure pulses or the pressures used immediately before ignition.

[0064] Figure 6 shows a schematic flow diagram for the simplest method shown in Figure 3. The method steps are each executed at the end of a cleaning interval, with the input of a measured value from one of the sensors 40. If this measured value is above the threshold value S1 of the upper first threshold value 62, the cleaning interval is shortened. Otherwise, the measured value is compared with the lower threshold value S2. If the measured value is below the threshold value S2 of the lower threshold value 62', the cleaning interval is extended.

[0065] As mentioned above, the flow chart of Fig. 6 can also be modified so that instead of or together with the change of the length of the

[0066] The cleaning energy is increased or decreased during the cleaning interval.

[0067] It should be noted that in the above examples a shortening of the

[0068] The cleaning interval or an increase in cleaning energy was always performed when the (upper) threshold was exceeded at the time of measurement. However, there are measured values ​​for which more intensive cleaning is required by shortening the cleaning interval or increasing the cleaning energy when a measured value is undershot. This is, of course, also covered by the above examples.

[0069] As mentioned above, a large number of sensors are typically deployed along the boiler wall in various areas. These can be similar sensors, such as flue gas temperature sensors, which then individually control cleaning devices along the length of the boiler system. It can also be several different sensors that are then used together to control the cleaning process. Figure 7 shows a schematic flow diagram for the use of multiple sensors 1 to n.

[0070] The embodiment of Fig. 7 shows method steps that are each carried out at the end of a cleaning interval, with the input of the measured values ​​of sensors 1 to n. For each of the sensors 1 to n, k threshold values ​​S11 to Skn are specified. If the measured value of the first sensor is above the threshold value S11, then the cleaning intensity 1 is specified. Otherwise, the measured value of the second sensor is compared with the threshold value of the second sensor in the same way and adjusted until finally a query is made as to whether the threshold value S1 n has been exceeded by the measured value of the nth sensor. In other words, if a measured value of one of the n sensors is above the respectively assigned upper threshold value, the cleaning intensity 1 is specified.

[0071] If, however, all measured values ​​are below the specified thresholds, the second stage of the measured value comparison with the second thresholds S21 to S2n of sensors 1 to n comes into play. Cleaning intensity 2 is then specified in the same way if one of the sensors exceeds the threshold assigned to it for this cleaning intensity. This is then performed for all specified cleaning intensities k.

[0072] It is essential that these comparisons are performed. The setting of the cleaning intensities 1 to k can then be solved differently using a cost function, for example, if a minimum number of sensors are required to exceed or fall below a threshold group.

[0073] Here, the (k+1)th cleaning intensity is the smallest cleaning intensity, the flow chart can also be constructed the other way around so that this (k+1)th cleaning intensity means the highest cleaning intensity, so that if all measured values ​​are below (or above) a threshold, this is set and depending on the number of measured values ​​lying between two thresholds, one of the neighboring cleaning intensities is then selected.

[0074] In the example shown in Fig. 7, if a threshold level is exceeded by one measured value, it is sufficient to set a higher or lower cleaning intensity. It can also be specified that this requires, for example, a threshold level being exceeded by two measured values ​​from four sensors.

[0075] LIST OF REFERENCE SYMBOLS

[0076] 10 boiler section

[0077] 11 Flue gas path

[0078] 12 Start of boiler section

[0079] 13 End of boiler section

[0080] 20 Cleaning device

[0081] 30 Control unit

[0082] 31 Signal connection

[0083] 40 sensors

[0084] 41 Data line

[0085] 51 Development of measured values ​​in the state of the art

[0086] 51' Development of measured values ​​in the state of the art

[0087] 52 Maximum value

[0088] 52 Maximum value as threshold

[0089] 53 Cleaning interval

[0090] 53' cleaning interval

[0091] 54 Measurement interval (schematically exaggerated)

[0092] 61 Development of measured values ​​in an example

[0093] 62 first threshold

[0094] 62' second threshold

[0095] 63 Cleaning interval

[0096] 63' cleaning interval

[0097] 64 Cleaning energy

[0098] 64' Cleaning energy t1, t2, t3, t3' Measurement time t10, t11, t12, t13 Times before, during and after cleaning

[0099] 65 dead time

Claims

PATENT CLAIMS 1. A method for cleaning a pressure-resistant boiler area (10) with pressure pulses (21) generated by a cleaning device (20), which are guided into the boiler (10) via a discharge opening (22) assigned to the cleaning device (20), wherein a control unit (30) emits a pressure pulse into the boiler area (10) at predetermined cleaning intervals (63) by the cleaning device (20) to generate pressure pulses, characterized in that a sensor (40) records a measured value characterizing the degree of contamination of the boiler, which is compared with a predetermined first threshold value (62), wherein, depending on the correlation of the measured value with the degree of contamination, the cleaning interval (63) is set to a shorter cleaning interval (63') and / or the cleaning energy (64) is set to a higher cleaning energy (64') if the first threshold value (62) is exceeded or not reached.

2. Method according to claim 1, characterized in that the measured value used for the comparison with the threshold value, which characterizes the degree of contamination of the boiler, is determined from several measured values ​​determined by the sensor (40), in particular as an average value, maximum value or minimum value.

3. Method according to claim 1 or 2, characterized in that each time the first threshold value (62) is exceeded or undershot, the cleaning interval is set to an even shorter cleaning interval and / or the cleaning energy (64) is set to an even higher cleaning energy.

4. Method according to one of claims 1 to 3, characterized in that a second threshold value (62') is provided which has a smaller value than the first threshold value (62), wherein, depending on the correlation of the measured value with the degree of contamination, if the second threshold value (62') is undershot or exceeded, the cleaning interval (63') is set to a longer cleaning interval (63) and / or the cleaning energy (64') is set to a lower cleaning energy (64).

5. Method according to claim 4, characterized in that each time the second threshold value (62') is exceeded or undershot, the Cleaning interval is set to an even longer cleaning interval and / or the cleaning energy is set to an even lower cleaning energy.

6. Method according to one of claims 1 to 5, characterized in that a cleaning intensity is predetermined from the values ​​of cleaning intervals and cleaning energy quantities, and in that n sensors are provided, where n>=2, the next higher cleaning intensity being selected when the measured value of at least one of the n sensors exceeds the upper threshold value of the corresponding sensor or falls below the lower threshold value of the corresponding sensor.

7. Method according to claim 6, characterized in that an input of a value defining the degree of contamination is provided as the measured value of one of the sensors.

8. Method according to claim 6 or 7, characterized in that k+1 cleaning intensities are provided, where k>=1 and the (k+1)th cleaning intensity is the lowest cleaning intensity, that an i-th cleaning intensity is selected if at least the measured value of at least one of the n sensors exceeds the i-th threshold value of the corresponding sensor, but no measured value of one of the n sensors exceeds the (i-1)th threshold value, where i=2 to k, and that in the event that no measured value of the n sensors exceeds the k-th threshold value of the corresponding sensor, the (k+1)th cleaning intensity is selected.

9. Method according to one of claims 1 to 8, characterized in that when using a measured value characterizing the degree of contamination of the boiler by a sensor (40), in which a higher degree of contamination corresponds to a lower measured value, the measured value used in the method is an inverted or negative measured value of said sensor (40).

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