DE102019112355A1 - Method and device for the continuous measurement of at least one parameter of substances - Google Patents

Abstract

The present invention relates to a method and a device (50) with which a continuous measurement of at least one parameter of substances is made possible without the measuring sensor system entering its saturation range, the measurement being inexpensive and low-maintenance. In particular, a continuous measurement of particles in measurement gases is provided, in which the detection of dynamic concentrations is possible without the use of external diluent gas and in which at the same time the sensors are protected from excessive contamination by the measurement gas containing particles. If the measurable maximum of the measured substance parameter is exceeded, substance components are temporarily and proportionally deposited in a defined manner and fed back to the measurement at a later point in time. As a result, increased sensor measured values can be recorded in the measuring sensor system (58) over the period of (self) cleaning of the electrostatic filter (56) after it has been switched off. This reliably enables the provision of mean values of the substance parameters over a defined time range, such as half-hour, hourly or daily mean values.

Description

The present invention relates to a method for the continuous measurement of at least one parameter of substances according to the preamble of claim 1 and a device for the continuous measurement of at least one parameter of substances according to the preamble of claim 6.

Such devices and methods are used, for example, for the continuous measurement of dust concentrations in flue gases and, above all, in industry. However, they can also be used for other commercial and municipal purposes, such as monitoring compliance with fine dust limit values in the construction industry or in agriculture. Measurement gas is usually withdrawn from a gas flow by a probe, which is why we speak of an extractive measurement.

On the other hand, continuous measurement directly in the ambient air or exhaust air is also possible, which is referred to as in-situ measurement.

Since, for example, the dust concentration in industry during start-up processes, but above all in the construction industry or in agriculture, due to time-limited activities with high emissions, is highly dynamic, there is a possibility that previous sensor systems could become saturated. This leads to incorrectly detected measured values and incorrect storage of the measured values, which can be performed at longer time intervals, e.g. half an hour or an hour, falsified mean values to be recorded. The background to this is the saturation of the sensors, so that only the maximum measured value in the measured value range of the sensor is recorded and any dust concentration above this is lost for further recording and thus also for the time average.

To avoid this, a dilution system is currently being used 10 to protect the measuring sensors 12 used (cf. 1 ), which by introducing a defined volume flow 14th the dust concentration in the with the via a sample gas sampling probe 16 withdrawn sample gas 18th combined total volume flow 20th defined reduced. In order to achieve this dilution, the dilution gas must 22nd by means of an air treatment system 24 cleaned so that the diluent gas 22nd meets the requirements for instrument air (instrument air). This is cleaned, dry and dust-free ambient air.

Furthermore is for the introduction of the diluent gas 22nd a controlled fan 26th to be integrated to the volume flow to be introduced 14th to be able to vary in its amount. The regulation 28 is through in the sample gas volume flow 18th as in the diluent gas volume flow 14th characteristic values to be determined 30th , 32 The physical quantities pressure (p), velocity (v), temperature (T) and humidity (H) are supplied with information and then the dilution with the defined ratio is set in a mixing container 34 one. After measuring this generated total volume flow 20th in measurement sensors 12 becomes exhaust 36 issued.

The use of an expensive, precise control 28 that are not only determined by the characteristic values 30th , 32 , but also from the measurement sensors 12 Receives control signals and sends control signals to the fan 26th and air treatment 24 outputs, as well as the complex and also cost-intensive air treatment 24 maintaining I air leads to high system costs. Furthermore, because of the large number of additional mechanical components, the maintenance and repair costs are very high.

The aforementioned properties mean that these measuring systems cannot be operated economically in a large number of potential locations, which has hitherto stood in the way of their widespread use.

The object of the present invention is therefore to enable the continuous measurement of material parameters without the measuring sensor system entering its saturation range, the measurement being carried out inexpensively and with little maintenance. In particular, a continuous measurement of particles in measurement gases is to be provided, in which the detection of dynamic concentrations is possible without the use of diluent gas and in which, at the same time, the sensors are protected from excessive contamination by the measurement gas containing particles. In this way, the maintenance effort of the measuring systems is to be minimized as far as possible and a cost-effective alternative for use in particle measuring systems with a highly dynamic measurement value curve is to be created.

This object is achieved with the method according to the invention according to claim 1 and the device according to the invention according to claim 6. Advantageous further developments are given in the dependent claims and the description.

On the part of the invention, it was recognized that the problem posed can be achieved particularly easily in a surprising manner if the reaching of the saturation range of the sensor system is prevented by electrostatic filtering of the substances. It is thus the substance concentration in the Measurement sensors are preferably reduced in a targeted manner so that the measurement sensors remain in their optimal working point.

The method according to the invention for the continuous measurement of substances in a gas stream, with means for measuring at least one parameter of the substances and means for supplying the substances to the means for measurement, the means for measuring having a saturation range, is characterized in that the substance concentration is reduced in the means for supply by electrostatic filtering so that the saturation range is not reached.

"Continuous" means that the gas to be measured is continuously measured at least over a certain period of time. “Measuring” here means the determination of at least one physical and / or chemical parameter, the particle concentration preferably being determined. “Substances” can be all types of materials, in particular they can be solids, for example particles, but also gases or aerosols, including chemical substances such as SO3 or the like. “Parameters” can be any physical and / or chemical parameters of the substance, preferably a dust concentration in a measurement gas.

In an advantageous development it is provided that the electrostatic filtering is switched on when there is a risk that the saturation range will be reached. In this way, it is possible to react to a possible reaching of the saturation range at an early stage and thus to maintain the optimal working point of the measuring sensors. For this purpose, for example, a threshold value could be used which is below a saturation value of the measuring sensor system.

In an advantageous development, it is provided that the risk of reaching the saturation range is recognized by means of an edge analysis in relation to the continuous measured value curve. For example, the first derivative of this measured value curve can be analyzed in connection with the current measured value to determine whether the saturation range is reached. The measured value can then be reduced in a targeted and dynamic manner or subsequently increased again through electrostatic filtering.

In an advantageous development it is provided that the electrostatic filtering is carried out with at least one electrostatic precipitator, which is preferably an electric separator. This enables electrostatic filtering to be particularly effective.

Basically, it was recognized that, for example, for extractive, continuous determination of measured values at a flow rate of the measuring gas of up to 15 m / s, the use of a filtering process, e.g. according to the electrostatic principle using an E-filter is possible. The filter effect can be improved by specifically adapting the filter architecture, e.g. in the surface properties of the separation electrode or the effective filter length. The dilution can take place with a single feed line in which a filter system consisting of one or more filters connected in series is integrated. The filter intensity of this or these filters can be set in a targeted manner by a control unit in accordance with the substance concentration. In this way, a precise dilution of the suctioned measuring gas is realized.

It was recognized that with an electrostatic precipitator the cleaning of inflowing, non-explosive or non-flammable gases can be achieved with an efficiency of over 95% if the flow velocity is in a low range of less than 2m / s. In an advantageous further development, it is therefore provided that the flow against the electrostatic filter is at a flow velocity of the substances of at most 2 m / s, preferably at most 1 m / s, in particular at most 0.7 m / s. If the flow rate in the electrostatic filter is greater than the desired flow rate, then part of the volume flow can be branched off, wherein the branch line or the branch lines can also have a filter system. Furthermore, the filter space can be designed with a diameter that is larger than that of the supply line.

The filter effect can be improved even further if the flow rate within the electrostatic filter is reduced to at most 0.5 m / s, preferably at most 0.2 m / s, in particular at most 0.1 m / s. For this purpose, the filter space can be designed with a diameter that is larger than that of the supply line.

The flow velocity can also be reduced by connecting several flow lines in parallel.

“Diameter” does not limit the line or supply line to those with a circular cross-section. Other cross-sections, such as angular or oval, are also possible, in which case “enlarged diameter” means an enlarged area through which the air flows.

In an advantageous development it is provided that the filtered out substances of Measurement can be supplied again at a later point in time if there is no risk of the saturation range being reached, the supply preferably being carried out by cleaning the filter. This makes it very easy to determine the exact mean value for the measured values over a certain period of time, because no substances are lost for the measurement and thus a temporary extension of the measuring range is carried out.

Independent protection is claimed for the device according to the invention for the continuous measurement of substances in a gas stream, with means for measuring at least one parameter of the substances and means for supplying the substances to the means for measurement, the means for measuring having a saturation range that thereby is characterized in that there are means for electrostatic filtering of the substances and means for control which are adapted to control the means for electrostatic filtering in such a way that the substance concentration in the means for supply is reduced so that the saturation range is not reached.

In an advantageous development it is provided that the means for supplying have at least two parallel conduction path areas, with electrostatic filtering being able to be carried out in at least one conduction path area. As a result, a purge gas generated by filtering measurement gas can be produced very easily and fed to the measurement gas. Due to this volume flow separation, lines with different or equally large diameters can be used in order to specifically influence the ratio of the purge gas to the measurement gas. In addition, the supply lines for measuring gas and for flushing gas can be provided with throttle valves in order to set the mixing ratio in a targeted manner. In addition, there can be several feed lines for the measurement gas as well as for the flushing gas, which are preferably designed to be selectively switched off, for example with throttle or switching valves.

In an advantageous development it is provided that the filtering means have at least one electrostatic precipitator, preferably at least one electrostatic precipitator. These filters are particularly easy to manufacture and operate. Two or more electrostatic precipitators can also be connected in parallel and / or in series, as a result of which the filtered amount of substance and thus the purity of the purge gas generated can be adjusted in a targeted manner. The structure and mode of operation of such an electrostatic filter can, for example, be the EP 3 396 352 A1 are taken, the relevant content of which is hereby included.

In the present invention, the dynamic setting of the temporary dilution ratio can therefore either be carried out by connecting or disconnecting electrostatic filters and / or purge gas feed lines on the one hand and / or on the other hand by means of defined control of the electrostatic filter or the electrostatic filter using determined filter characteristics.

In an advantageous development it is provided that the means for filtering have means for cleaning which are adapted to release the filtered substances, the means for cleaning preferably being designed as knocking and / or vibrating means. As a result, the filtered substances can also be fed back into the measurement later if they cannot be removed from the electrostatic precipitator and discharged by simply switching it off and flowing through the electrostatic precipitator with measuring gas.

In an advantageous development it is provided that the device is adapted to carry out the method according to the invention.

In an advantageous further development, it is provided that the means for filtering are arranged upstream of the means for conditioning, the means for conditioning preferably having at least one means from the group comprising drying means and temperature control means. This means that inexpensive control technology can be used in the supply system. Compliance with the boundary conditions of the sample gas is necessary for use. The measuring gas introduced must have a temperature of at least 5 ° C above its dew point and be neither explosive nor flammable. The background to this is the passage through the electrostatic field, in which sparks can form due to the use of high voltage between the spray electrode and the separation electrode as well as on particles in the measurement gas. To reduce the boundary conditions, an upstream conditioning unit is intended to be added to the system as an optional module, whereby the influence of moisture and possibly precipitation phenomena when the dew point of the respective gas or gas mixture is not reached can be avoided.

In the context of the present invention, a method and a device are specified with which a very effective sensor protection is made possible and also the measuring range of continuous material measuring systems can be expanded.

• 1 eine Vorrichtung und das entsprechende Verfahren nach dem Stand der Technik in einer Blockbilddarstellung,
• 2 die erfindungsgemäße Vorrichtung und das erfindungsgemäße Verfahren in einer ersten bevorzugten Ausführungsform in einer Blockbilddarstellung,
• 3 die erfindungsgemäße Vorrichtung und das erfindungsgemäße Verfahren in einer zweiten bevorzugten Ausführungsform in einer Blockbilddarstellung,
• 4 die erfindungsgemäße Vorrichtung und das erfindungsgemäße Verfahren in einer dritten bevorzugten Ausführungsform in einer Blockbilddarstellung,
• 5 die erfindungsgemäße Vorrichtung und das erfindungsgemäße Verfahren in einer vierten bevorzugten Ausführungsform in einer Blockbilddarstellung,
• 6 den Messungsablauf in einer beispielhaften Messwertdarstellung für die Ausführungsform nach 2,
• 7 einen erfindungsgemäß eingesetzten elektrostatischen Filter in einer ersten Schnittansicht und
• 8 den elektrostatischen Filter nach 7 in einer zweiten Schnittansicht.

The characteristics and further advantages of the present invention will become clear in the following on the basis of the description of preferred exemplary embodiments in connection with the figures. It shows purely schematically:

• 1 a device and the corresponding method according to the state of the art in a block diagram,
• 2 the device according to the invention and the method according to the invention in a first preferred embodiment in a block diagram,
• 3 the device according to the invention and the method according to the invention in a second preferred embodiment in a block diagram,
• 4th the device according to the invention and the method according to the invention in a third preferred embodiment in a block diagram,
• 5 the device according to the invention and the method according to the invention in a fourth preferred embodiment in a block diagram,
• 6th the measurement sequence in an exemplary measurement value display for the embodiment according to 2 ,
• 7th an electrostatic filter used according to the invention in a first sectional view and
• 8th the electrostatic filter 7th in a second sectional view.

In 2 is a first preferred embodiment of the device according to the invention 50 shown.

It can be seen that this device 50 a sampling probe 52 for gas to be examined 54 has an electrostatic filter 56 and measuring sensors 58 .

The gas 54 , which is either in a room or in an area (for example a chimney) is guided by the sampling probe 52 Sample gas 60 removed and an electrostatic filter 56 fed. Then the mixed gas leaving the filter becomes 62 the measuring sensors 58 fed and measured. (In the following, “mixed gas” is always used instead of “measurement gas” when the measurement gas has been subjected to a treatment, eg filtering or rinsing.) This is where the electrostatic filter 56 so by means of a control unit 64 regulated that the measuring sensors 58 does not get into their saturation range. That from the measurement sensors 58 Exiting mixed gas is called exhaust gas 66 issued.

With this configuration 50 it is expected that the electrostatic filter will have a sufficiently high filter effect 56 provided. The flow velocities through the electrostatic filter should be used 56 for example not be greater than 0.5 m / s.

In 3 is a second preferred embodiment of the device according to the invention 100 shown.

It can be seen that this device 100 a sampling probe 102 for gas to be examined 104 has a volume flow divider 106 , an electrostatic filter 108 , a volume flow mixer 110 , Measuring sensors 112 and a control unit 114 .

The gas 104 , which in turn is either in a room or in an area (for example a chimney) is guided by the sampling probe 102 Sample gas 116 removed and the volume flow divider 106 fed.

The volume flow divider 106 divides the sample gas 116 into a sample gas portion 118 and a purge gas portion 120 . The purge gas portion 120 is through the electrostatic filter 108 and then with the sample gas portion 118 in the volume flow mixer 110 merged again, so mixed. The mixed gas generated 122 becomes the measuring sensors 58 fed and measured there. Thereby the electrostatic filter 108 so by means of the control unit 114 regulated that the measuring sensors 112 does not get into their saturation range. That from the measurement sensors 112 Exiting mixed gas is called exhaust gas 124 issued.

For the device 100 form the volume flow divider 106 , the electrostatic filter 108 and the volume flow combiner 110 together the filter unit 126 .

In the present case, the volume flow divider is 106 a purely static component in which an input line is invariably coupled to two different output lines.

It can be at the flow divider 106 however, it can also be a variable component (not shown) in which, for example, the passage of one outlet is designed to be variable or, when the passage of one outlet is enlarged, the passage of the other outlet is reduced. Then this volume flow divider can also be controlled by the control unit 114 can be regulated as a function of the measurement signal.

Instead of an unfiltered sample gas portion 118 could also be an electrostatic filter in this branch 108 used so that two electrostatic filters connected in parallel 108 exist and not an unfiltered sample gas branch.

In 4th is a third preferred embodiment of the device according to the invention 150 shown.

It can be seen that this device 150 a sampling probe 152 for gas to be examined 154 has a volume flow divider 156 , two electrostatic filters 158 , 160 , a volume flow combiner 162 , Measuring sensors 164 and a control unit 166 .

The gas 154 , which is either in a room or in an area (for example a chimney) is guided by the sampling probe 152 Sample gas 168 removed and the volume flow divider 156 fed.

The volume flow divider 156 divides the sample gas 168 into a sample gas portion 170 and two purge gas portions 172 , 174 . Each purge gas portion 172 can through its own electrostatic filter 158 , 160 and then with the sample gas portion 170 in the volume flow mixer 162 merged again, i.e. mixed. The mixed gas generated 176 becomes the measuring sensors 164 fed and measured there. Thereby the electrostatic filter 158 , 160 so by means of the control unit 166 regulated that the measuring sensors 164 does not get into their saturation range. That from the measurement sensors 164 Exiting mixed gas is called exhaust gas 178 issued.

For the device 150 form the volume flow divider 156 who have favourited Electrostatic Filters 158 , 160 and the volume flow mixer 162 together the filter unit 180 .

In contrast to the device 100 after 3 there are thus two different purge gas line components 172 , 174 through the separate electrostatic filter 158 , 160 can be specifically influenced with regard to the substances contained. So the substance concentration in the generated mixed gas 176 can be adjusted even better.

Any number of purging gas lines and measuring gas lines can exist in parallel, and measuring gas lines can be dispensed with entirely, in which case all lines are provided with an electrostatic filter that can be switched on.

In 5 is a fourth preferred embodiment of the device according to the invention 200 shown.

It can be seen that this device 200 a sampling probe 202 for gas to be examined 204 has a first electrostatic filter 206 , a second electrostatic filter 208 , Measuring sensors 210 and a control unit 212 .

The gas 204 , this one in the chimney 214 an incinerator not shown 216 is performed (it is therefore an "emission measurement"), is performed by the sampling probe 202 Sample gas 218 removed and the first electrostatic filter 206 fed. Before there is the prepared mixed gas 220 the second electrostatic filter 210 fed, which in turn the measuring sensors 210 feeds 222 .

Thereby the electrostatic filter 208 , 210 so by means of the control unit 212 regulated that the measuring sensors 210 does not get into their saturation range. That from the measurement sensors 210 Exiting mixed gas is called exhaust gas 224 issued.

The drive for this feed comes from an ejector 226 , which by means of a fan 228 , the ambient air 230 sucks, is operated, the ejector 226 the exhaust 224 sucks in and the mixture of exhaust gas 224 and ambient air 230 as exhaust air 232 issues.

In contrast to the device 100 after 2 there are thus two electrostatic filters connected in series 206 , 208 , through which the substance concentration in the generated mixed gas 222 can be adjusted even better.

It can be seen that one or more electrostatic filters are used in the present invention 56 , 108 , 158 , 169 , 206 , 208 can use. These filters 56 , 206 , 208 can be in the sample gas line itself, as in 2 and 5 shown. Or the filters 108 , 158 , 160 can be in their own purge gas lines, as in 3 and 4th shown. A plurality of electrostatic filters (not shown) can also be present in such flushing lines.

For the device 200 form the electrostatic filters 206 , 208 together the filter unit 234 .

Based on 6th the measurement sequence should be based on an exemplary measurement value display for the embodiment according to 2 explained.

In this case, the dust concentration in the measurement gas becomes 54 determined, the measuring sensors 58 works according to the principle of optical scattered light measurement based on infrared in the usual way, which is readily known to the person skilled in the art.

The electrostatic filter used 56 is in the 7th and 8th shown in more detail in sectional views.

It can be seen that the electrostatic precipitator 56 an electrically insulating housing 70 having. The The housing is designed as a cylinder with two offset gas lines arranged opposite one another 72 , 74 , namely a gas supply line 72 for the supplied sample gas 60 and a gas discharge 74 for the electrostatic precipitator 56 leaving mixed gas 62 .

Inside the case 70 is a chamber 76 formed by a hollow cylindrical metal sleeve 78 is limited. This metal sleeve 78 forms the separation electrode 78 connected to the electrical connection 80 a potential can be applied. This is preferably earth potential.

In the middle of the chamber 76 is a spray electrode 82 arranged so that the deposition electrode 78 this is arranged concentrically. This spray electrode 82 has a maximum thickness of 1 mm. It is preferred as a smooth industrial needle 82 Made of stainless steel because, in contrast to wires and the like, this has a very long service life in operation and also does not require any separate clamping means. Also has the spray electrode 82 an electrical connection 84 for applying a potential, in the present case preferably a high DC voltage, for example of a maximum of 15 kV, the voltage supply preferably being pulsed. The reference voltage on the spray electrode can be either positive or negative.

Because the cross-sectional area of the gas supply line 72 is much smaller than the significantly larger cross-sectional area of the chamber 76 , for example a ratio of 1 to 10, the flow rate in the chamber 76 slowed down significantly, so that the electrodeposition takes place very effectively by reducing the speed of the gas flow.

The electrodeposition takes place by applying, for example, 15 kV negatively pulsed DC voltage to the spray electrode 82 with which electrons are released. These electrons are in the very strong electric field that forms between the spray electrode 82 and the separation electrode 78 strongly accelerated and hit the dust particles (not shown). These dust particles are then electrically charged. Due to the strong electric field, the charged dust particles become the separation electrode 78 transported. There they are unloaded and deposited due to adhesive forces.

In this way, the dust particles can be completely filtered out of the measuring gas 60 respectively. The proportion of through the electrostatic precipitator 56 Filtered out dust particles can be applied to the spray cathode by changing the applied potential 82 can be set. Depending on the operation of the electrostatic precipitator 56 can thus reduce the dust particle concentration in the electrostatic precipitator 56 leaving mixed gas 62 can be changed in a targeted manner.

In 6th it can be seen that the measuring sensors 58 has a certain upper measuring range limit. If this measuring range limit is exceeded, the measuring sensors are saturated 58 so that no measured values greater than this measuring range limit can be determined.

It is now in the control unit 64 defines a threshold value that is sufficiently below the measuring range limit so that the dust concentration by means of the electrostatic precipitator is used in common applications 56 can be lowered sufficiently without exceeding the measuring range limit value.

In 6th On the one hand, an actual course of a dust concentration is shown and that actually from the measuring sensors 58 output measured values if the measuring range limit would not exist (in 6th referred to as "dust concentration").

It becomes clear that the measured values to be expected in the time segment 1 (in 6th by the circled " 1 “Clarified) between the times T1 and T2 would exceed the measuring range limit. Since during this period the measuring sensors 58 would go into saturation, only measured values in the amount of the measuring range limit value could be output and recorded, so that the respective current measured values would be falsified. In addition, the average values based on them would also be faulty, since the dust concentrations above the measuring range limit would be ignored.

According to the invention it is now provided that the control unit 64 if the current measured value exceeds the threshold, the electrostatic precipitator 56 switches on and regulates so that the measured value remains below the measuring range limit. This switching on the electrostatic precipitator 56 takes place in 6th at the time T1 indicated by the first vertical auxiliary line (viewed from the left).

To be able to assess how strong the electrostatic precipitator is 56 The control unit determines how many dust particles are to be filtered out for this purpose 64 the edge rise, i.e. the first derivative of the measured value curve when the threshold value is exceeded and represents the potential at the spray cathode 82 depending on the previously determined characteristic curve of the electrostatic precipitator 56 so that the measuring range limit is definitely not exceeded.

The second vertical guide at the point in time T2 refers to the point in time when the actual measured values would fall below the measuring range limit again. However, it occurs through the flow through the electrostatic precipitator 56 dust particles that have already been filtered are always taken along, i.e. those from the separation electrode 78 blown away and to the measuring sensors 58 are issued.

This extends the time period up to the point in time T3 , which is indicated by the third vertical auxiliary line, until the measured values fall below the threshold value again. At this point the electrostatic precipitator will 56 through the control unit 64 switched off. The filtering of the dust particles is thus in the period between T1 and T3 performed. To ensure that the undershoot is stable, an edge analysis can also be carried out here with regard to the negative edge rise.

Due to the previously described widening of the separation electrode 78 adhering dust particles is the actual measured value up to the point in time T4 , which is made clear by the fourth vertical auxiliary line, is still above the expected measured value for the actually in the measuring gas 60 contained dust concentration. The period 2 (in 6th by a circled " 2 “Denotes) between times T3 and T4 thus describes the period in which the filter is cleaned.

This filter cleaning takes place passively by blowing out the dust particles. However, active filter cleaning, for example by means of knocking agents and / or vibrating means (both not shown in FIGS 7th and 8th ) are used, thereby reducing the period 2 would be shortened.

When the measurable maximum of the dust particle concentration is exceeded, dust particles are temporarily and proportionally deposited in a defined manner and fed back to the measurement at a later point in time. This means that in the measurement sensors 58 increased sensor readings over the period of self-cleaning of the electrostatic precipitator 56 after it has been switched off.

More precisely, the complete registration of the dust particle concentration in the mixed gas takes place 62 hereinafter in the device 50 (the integrals under the curves for the dust concentration and the measured values are in 6th are identical). Before switching off the electrostatic precipitator 56 the sensor measured values are checked for their increase and, given a defined stability, the time span since the electrostatic precipitator was switched on 56 determined. By means of the integral of the recorded by the electrostatic precipitator 56 influenced sensor readings, over the determined time span T1-T4 , is the calculation of the total by the device 50 flow of dust particles possible. This is added to the previously and subsequently determined measured values in the device-specific measuring range and thus enables the provision of legally required mean values for the dust particle concentration in the gas 54 over a defined time range. Half-hourly, hourly or daily mean values are common calculation values.

Even if this measurement example is based on the device 50 in relation to dust particle concentrations, it is clear that this procedure can also be used for others, such as in the 3 to 5 devices shown 100 , 150 , 200 Is valid. In the event that several electrostatic precipitators are used 158 , 160 , and / or one or more purging gases 120 , 172 , 174 the device is not on the filter function of an electrostatic filter, but on the filter function of the entire filter unit 126 , 180 , 234 turn off. In addition, other physical and / or chemical parameters of gases can be determined with this procedure than dust particle concentrations.

In addition, it could be in front of the respective electrostatic precipitators 56 , 108 , 158 , 160 , 206 , 208 a conditioning means (not shown) can be arranged around the measuring gas supplied to the electrostatic precipitators 60 , 120 , 172 , 174 , 218 to be conditioned so that neither the dew point of the sample gas 60 , 120 , 172 , 174 , 218 The sample gas is still reached or undercut 60 , 120 , 172 , 174 , 218 is explosive or flammable. So should the introduced sample gas 60 , 120 , 172 , 174 , 218 have a temperature of at least 5 ° C above its dew point. The background is the passage through the electrostatic field in the electrostatic precipitators 56 , 108 , 158 , 160 , 206 , 208 in which it is achieved through the use of high voltage between the spray electrode 82 and the separation electrode 78 as well as particles in the sample gas 60 , 120 , 172 , 174 , 218 sparking can occur. Suitable conditioning prevents the influence of moisture and possibly precipitation phenomena if the respective gas or gas mixture falls below the dew point.

It has become clear from the above illustration that the present invention enables a continuous measurement of at least one parameter of substances without the measurement sensors entering their saturation range, whereby the measurement can be carried out inexpensively and with little maintenance. In particular, a continuous measurement of particles in measurement gases is provided, in which the detection of dynamic concentrations is possible without the use of external diluent gas and in which the sensors are present at the same time is protected from excessive contamination by the sample gas containing particles. In this way, the maintenance effort of the measuring systems is minimized as far as possible and an inexpensive alternative for use in material measuring systems with a highly dynamic measurement value curve is created. If the measurable maximum of the measured substance parameter is exceeded, substance fractions are temporarily and proportionally deposited in a defined manner and returned to the measurement at a later point in time. This allows in the measurement sensors 58 increased sensor readings over the period of (self) cleaning of the electrostatic filter 56 after it has been switched off. This enables the provision of mean values of the substance parameters over a defined time range, such as half-hour, hourly or daily mean values. Overall, very effective sensor protection is made possible and the measuring range of continuous material measuring systems can also be expanded.

Unless otherwise stated, all features of the present invention can be freely combined with one another. Unless otherwise stated, the features described in the description of the figures can also be freely combined with the other features as features of the invention. A limitation of individual features of the exemplary embodiment to the combination with other features of the exemplary embodiment is expressly not provided; these individual features can be used independently for combination with other features, in particular features specified in the set of claims. In addition, objective features, reformulated, can also be used as process features and process features, reformulated, as objective features. Such a reformulation is therefore automatically disclosed.

List of reference symbols

10

Dilution system 10 According to the state of the art

12

Measuring sensors

14th

defined volume flow

16

Sample gas sampling probe

18th

Sample gas

20th

Total volume flow

22nd

Diluent gas

24

Air treatment system

26th

controlled fan

28

regulation

30, 32

Determination of characteristic values

34

Mixing tank

36

Exhaust gas

50

first preferred embodiment of the device according to the invention

52

Sampling probe

54

gas to be examined

56

electrostatic filter

58

Measuring sensors

60

Sample gas

62

that the filter 56 leaving mixed gas

64

Control unit

66

Exhaust gas

70

electrically insulating housing 70 of the electrostatic precipitator 56

72

Gas supply line

74

Gas discharge

76

chamber

78

hollow cylindrical metal sleeve, deposition electrode

80

electrical connection

82

Spray electrode, smooth industrial needle made of stainless steel

84

electrical connection

100

second preferred embodiment of the device according to the invention

102

Sampling probe

104

gas to be examined

106

Flow divider

108

electrostatic filter

110

Volume flow mixer

112

Measuring sensors

114

Control unit

116

Sample gas

118

Sample gas portion

120

Purge gas proportion

122

Mixed gas

124

Exhaust gas

126

Filter unit from volume flow divider 106 , electrostatic filter 108 and volume flow combiner 110

150

third preferred embodiment of the device according to the invention

152

Sampling probe

154

gas to be examined

156

Flow divider

158, 160

electrostatic filters

162

Volume flow combiner

164

Measuring sensors

166

Control unit

168

Sample gas

170

Sample gas portion

172, 174

Purge gas proportions

158, 160

electrostatic filters

176

Mixed gas

178

Exhaust gas

180

Filter unit from volume flow divider 156 , electrostatic filters 158 , 160 and volume flow combiner 162

200

fourth preferred embodiment of the device according to the invention

202

Sampling probe

204

gas to be examined

206

first electrostatic filter

208

second electrostatic filter

210

Measuring sensors

212

Control unit

214

chimney

216

Incinerator

218

Sample gas

220

pre-prepared mixed gas

222

final mixed gas

224

Exhaust gas

226

Ejector

228

fan

230

Ambient air

232

Exhaust air

234

Filter unit made up of electrostatic filters 206 , 208

QUOTES INCLUDED IN THE DESCRIPTION

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Patent literature cited

• EP 3396352 A1 [0025]

Claims (10)

A method for the continuous measurement of substances in a gas stream (60; 116; 168; 218), wherein there are means (58; 112; 210) for measuring at least one parameter of the substances and means for supplying the substances to the means for measuring, the Means (58; 112; 210) for measurement have a saturation range, characterized in that the substance concentration in the means for supply is reduced by electrostatic filtering (56; 108; 158, 160; 206, 208) so that the saturation range is not reached . Procedure according to Claim 1 , characterized in that the electrostatic filtering (56; 108; 158, 160; 206, 208) is switched on when there is a risk that the saturation range will be reached. Procedure according to Claim 2 , characterized in that the risk of reaching the saturation range is recognized by slope analysis in relation to the continuous measured value curve. Method according to one of the preceding claims, characterized in that the electrostatic filtering is carried out with at least one electrostatic precipitator, which is preferably an electrostatic precipitator (56; 108; 158, 160; 206, 208). Method according to one of the preceding claims, characterized in that the substances filtered out are fed back into the measurement at a later point in time when there is no risk of the saturation range being reached, the feed preferably being done by cleaning the filter (56; 108; 158 , 160; 206, 208). Device (50; 100; 150; 200) for the continuous measurement of substances in a gas stream (60; 116; 168; 218), means (58; 112; 210) for measuring at least one parameter of the substances and means for supplying the substances to the means (58; 112; 210) for measurement, the means (58; 112; 210) for measurement having a saturation range, characterized in that means (56; 108; 158, 160; 206, 208) for electrostatic Filtering of the substances and means (64; 116; 166; 212) for control which are adapted to control the means (56; 108; 158, 160; 206, 208) for electrostatic filtering in such a way that the substance concentration in the means for feeding is reduced so that the saturation range is not reached. Device (100; 150; 200) according to Claim 6 , characterized in that the means for supplying have at least two parallel conduction path areas (118, 120; 170, 172, 174), with electrostatic filtering (56; 108; 158, 160; in at least one conduction path area (120; 172, 174)). 206, 208) can be carried out. Device (50; 100; 150; 200) according to Claim 6 or 7th , characterized in that the means for filtering have at least one electrostatic filter, preferably at least one electrostatic precipitator (56; 108; 158, 160; 206, 208). Device (50; 100; 150; 200) according to one of the Claims 6 to 8th , characterized in that the means (56; 108; 158, 160; 206, 208) for filtering have means for cleaning which are adapted to release the filtered substances, the means for cleaning preferably being designed as knocking and / or vibrating means are. Device (50; 100; 150; 200) according to one of the Claims 6 to 9 , characterized in that the device is adapted to the method according to one of Claims 1 to 5 and / or that the means for filtering are preceded by means for conditioning, the means for conditioning preferably having at least one means from the group comprising drying means and temperature control means.

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