Photometric process measurement device and photometric measurement method

Abstract

A photometric process measurement device (10) comprises a photometric immersion probe (20) comprising a photometer flash light source (61) for providing photometric light pulses; a photometric detector device (70) comprising at least two separate wavelength selective detection elements (71, 72, 73); and a photometer controller (80) controlling the photometer flash light source (61) and the detector device (70), the photometer controller (80) comprising: a pulse signal integrator (819, 829, 839) for one pulse integration cycle (204, 221, 264) integrating an electrical pulse having a pulse intensity (Ui) generated by the detection element (71, 72, 73), and a photometer controller (80) for controlling the photometer flash light source (61) and the detector device (70), the pulse signal integrator (819, 829, 839) for one pulse integration cycle (204, 221, 264); a measurement cycle controller (90) for adapting the total number of integrated cycle pulses of the pulse integration cycles (204, 221, 264) to the pulse intensity (Ui) of a single electrical pulse; an A / D converter (81, 82, 83) for converting a voltage of the pulse signal integrator (819, 829, 839) in an A / D conversion interval (100) after the pulse integration cycle (204, 221, 264); a flash driver module (120) for controlling a pulse ignition switch (36) that triggers the photometer flash source (61) at a pulse frequency (fi) during the pulse integration cycle (204, 221, 264); and a flash lamp thermal management module (130) for performing flash lamp thermal management in the pulse integration cycles (204; 204 '), for example by integrating the pulse integration cycles (204') in accordance with the number of cycle pulses being integrated. 221; 264), adding an adaptive pause interval (303; 311) for balancing the number of luminosity light pulses within a time frame (F) such that the total number of luminosity light pulses within said time frame (F) is substantially constant.

Description

Technical Field

[0001] The invention relates to a photometric process measuring device with a photometric immersion probe and a photometric measuring method provided by the photometric process measuring device. Background Art

[0002] A photometric process measuring device comprises a photometric immersion probe which is immersed in water of a water tank. The water tank may be part of a water treatment plant for continuously controlling drinking water or for controlling process steps of a wastewater treatment process. A typical photometric immersion probe is disclosed in DE 10 2005 007 142 A1. Prior art immersion probes comprise a photometric flash lamp source for providing photometric light pulses having a sufficiently continuous or quasi-continuous spectrum and a photometric detector arrangement having at least two separate wavelength selective detection elements.

[0003] In the prior art photometric controller, the wavelength selective detection element is provided with a pulse signal integrator for integrating the electrical pulses generated by the detection element. The pulse signal integrator is a capacitor with a saturation voltage which cannot be exceeded during the integration process within a measurement cycle, so that the number of flash light source flashes that can be integrated within one pulse integration cycle is limited.

[0004] The general application environment of the photometric process measuring device can be very clear drinking water and highly turbid waste water, so that the maximum acceptable number of flashes of the flash lamp source within one pulse integration cycle can range between very few flashes for very clear drinking water resulting in a relatively high pulse intensity for each single electrical pulse and more than one hundred flashes for very turbid waste water resulting in an extremely low pulse intensity for each single electrical pulse. However, the capacity of the pulse signal integrator should be utilized as much as possible to optimize the signal-to-noise ratio of the A / D conversion of the voltage for the pulse signal integrator. Therefore, the number of integrated electrical pulses of one pulse integration cycle is adapted to the turbidity of the sample water.

[0005] One pulse integration cycle of the measurement cycle may have only four pulses for very clear sample water, or may have, for example, more than one hundred pulses for very turbid sample water. The typical flash interval is 5 ms to 30 ms. After the pulse integration cycle, the A / D conversion of the voltage of the pulse signal integrator is provided. The A / D conversion interval usually takes 50 ms to 100 ms, and the photometer flash light source stops during the A / D conversion, and does not provide photometric light pulses. Therefore, within a limited time frame of, for example, 1 minute, the total number of photometric light pulses generated by the flash light source is substantially different from about 1300 flashes per minute for very clear sample water with only four 20 ms flashes per pulse integration cycle and many 100 ms A / D conversion intervals and 2800 flashes per minute for very turbid sample water with one hundred 20 ms flashes per pulse integration cycle and only a few 100 ms A / D conversion intervals.

[0006] This results in very different thermal conditions of the photometer flash source depending on the turbidity of the sample water. The thermal conditions of the photometer flash source substantially influence the emission spectrum of the flash source, and the different number of flashes per time frame significantly influences the lifetime of the flash source. Summary of the invention

[0007] It is an object of the present invention to provide a photometric process measurement device providing adaptive pulse integration cycle management and having improved thermal management of the photometer flash lamp source.

[0008] This object is achieved by means of a photometric process measuring device having the features of the independent device claim 1 and a photometric measuring method having the features of the independent method claim 8 .

[0009] The photometric process measuring device according to the invention is provided with a photometric immersion probe which is preferably continuously and completely immersed in the water of the pool. The immersion probe comprises a photometric flash light source for providing photometric light pulses with a suitable and sufficiently continuous spectrum, preferably with a spectrum focused on the ultraviolet range for determining, for example, the concentration of nitrates and nitrites. Preferably, the flash light source is a high-pressure gas discharge lamp, more preferably a xenon flash lamp.

[0010] The photometric detector arrangement comprises at least two separate wavelength selective detection elements, which may be a combination of a beam splitter, a wavelength selective filter and a photocell, or another suitable arrangement that allows wavelength selective detection of the intensity of at least two discrete wavelengths of the light pulses generated by the flash lamp source after transmission through the water sample. The photocell may be a silicon photocell, and the wavelength selective filter may be an interference bandpass filter.

[0011] The photometer controller controls the photometer flash source by triggering each flash source pulse. The photometer controller includes a pulse signal integrator for each detection element, which is used to integrate the electrical pulses generated by the corresponding detection element. The pulse signal integrator is preferably a capacitor. The photometer controller includes an A / D converter for converting the voltage of the pulse signal integrator. Each pulse signal integrator is provided with a corresponding A / D converter. Each A / D converter is provided with a high-precision conversion trigger port. If the high-precision conversion trigger port is electronically triggered, a high-precision A / D conversion is started. A / D conversion with high precision can take, for example, up to 100 milliseconds.

[0012] The photometer is provided with a flash lamp driver module for controlling a pulse ignition switch, which triggers the photometer flash lamp source during a pulse integration cycle. Typically, the pulse frequency may be adjustable. Preferably, the pulse frequency is completely constant for the life of the photometric process measuring device. Preferably, the constant pulse period is in the range of 10 ms to 30 ms.

[0013] The photometer controller is provided with a measuring cycle controller for adapting the total number of integrated cycle pulses of a pulse integration cycle to the pulse intensity of a single electrical pulse. In other words, the cycle length of the pulse integration cycle and the total number of pulses after which the A / D conversion is initiated are adapted to the turbidity of the sample water. If the sample water is relatively clear, the number of photometric light pulses generated to define an adaptive pulse integration cycle is relatively low. If the water sample is relatively turbid, the number of photometric light pulses used to define an adaptive pulse integration cycle is relatively high.

[0014] Adjustment of the length and the total number of integrated cyclic pulses of a pulse integration cycle can generally be achieved in many different ways.

[0015] This does not necessarily mean that such regulation is implemented for each single pulse integration cycle. Regulation can be provided flexibly or at fixed intervals, for example, every 20th pulse integration cycle or once per minute. Other measurement cycles, which are slave measurement cycles, are not regulated individually, but are identical to the adaptive measurement cycle, which is the master measurement cycle. This concept allows to spend more time accurately analyzing the master measurement cycle rather than the subsequent slave measurement cycles, without substantially degrading the overall measurement cycle frequency.

[0016] The flexible adjustment of the length of the measuring cycle allows the capacity of the pulse signal integrator and the A / D converter to be utilized to the greatest possible extent, so that the overall accuracy of the quantitative determination of the substances in the sample water is greatly increased.

[0017] The photometric controller is also provided with an A / D converter for converting the voltage of the pulse signal integrator in the A / D conversion interval after any pulse integration cycle. A typical A / D conversion interval takes 50 ms to 100 ms. Once the pulse integration cycle has ended, the photometer flash source is stopped and all A / D converters are triggered to read and digitize the voltage of the corresponding pulse signal integrator.

[0018] The photometer controller is provided with a flash lamp thermal management module for balancing the number of photometric light pulses within a time frame, which is a time reference much longer than the longest possible measurement cycle. The flash lamp from the management module balances the total number of photometric light pulses within the long time frame, so that the overall photometric light pulse frequency is constant independently of the pulse intensity and the resulting pulse integration cycle.

[0019] Typically, the balancing can be provided by adjusting the period between two photometric light pulses within a pulse integration cycle. Preferably, the flash lamp thermal management module balances the number of photometric light pulses within a time frame by adding an adaptive pause interval between the pulse integration cycles as needed. The length of the pause interval depends on the total number of integrated measurement cycle pulses of the pulse integration cycle, so that the total number of photometric light pulses within the considered time frame is substantially constant for an available range of different pulse integration cycles, the different pulse integration cycles having different total numbers of integrated cycle pulses resulting from different pulse intensities. If the pulse integration cycle is very short, no pause interval needs to be provided. The longer the measurement pulse integration cycle, the longer the pause interval provided between two subsequent pulse integration cycles.

[0020] The photometer controller preferably provides adaptive pause intervals between the pulse integration cycles to keep the overall photometric light pulse frequency substantially constant with reference to both relatively short time frames of several minutes and long time frames of at least several years of the measuring device life. This constancy has the physical effect that the electrodes of the photometer flash light source are driven at a very constant temperature so that the emission spectrum of the photometer flash light source is consistently maintained and photometric results are consistent over very long periods of time. In addition, the overall life of the photometer flash light source can be easily predicted by simply counting the photometric light pulses generated by the photometer flash light source. Other and more complex measures for supervising the condition of the photometer flash light source are unnecessary.

[0021] Preferably, the thermal management module adjusts the pause interval between the pulse integration cycles so that the constancy of the number of photometric light pulses within the time frame is within a tolerance of 10% for all available lengths of pulse integration cycles. More preferably, the constancy is within a tolerance of 5%.

[0022] Preferably, the adaptive pause interval is defined by one or more additional A / D conversion intervals. Thus, the pause interval is used to improve the accuracy of the A / D conversion process, since the total number of A / D conversions is substantially increased, particularly for relatively long pulse integration cycles.

[0023] According to a preferred embodiment of the invention, the measuring cycle controller comprises a cycle pattern table memory, which stores difference cycle patterns with defined pulse integration cycles and associated defined pause intervals. The measuring cycle controller selects a measuring cycle pattern with defined pulse integration cycles and defined pause intervals depending on the pulse intensity at the start of the pulse integration cycle. In other words, the length of the pulse integration cycle and the corresponding pause interval can be selected from only a very limited number of several measuring cycle patterns.

[0024] The available measurement cycle mode may, for example, have only pulse integration cycles with 4, 8, 16, 21, 32 or 64 integrated electrical pulses. Within a time frame of, for example, 3 seconds, a single pulse integration cycle with 64 integrated electrical pulses, two pulse integration cycles with 32 integrated electrical pulses, three pulse integration cycles with 21 integrated electrical pulses, four pulse integration cycles with 16 integrated electrical pulses, eight pulse integration cycles with 8 integrated electrical pulses, and sixteen pulse integration cycles with only 4 integrated electrical pulses may be available as part of the available measurement cycle mode. Therefore, the total number of integrated electrical pulses within the time frame is always 63 or 64. The length of the relevant pause interval is adjusted and defined accordingly.

[0025] At the beginning of the pulse integration cycle, for example, after two or three received and integrated electrical pulses, a decision is made regarding the length of the adaptive pulse integration cycle or the appropriate measurement cycle mode. The selected measurement cycle mode may be maintained for several time frames or time intervals before a new decision regarding the appropriate measurement cycle mode is provided.

[0026] Using a cyclic pattern table memory is relatively simple and does not require substantial computing power.

[0027] There are usually different technical ways to monitor the development of said voltage of said pulsed signal integrator during a pulse integration cycle. Preferably, the monitoring is not realized by providing a high-precision A / D conversion after each single flash lamp pulse, since a high-precision A / D conversion is relatively time-consuming and takes more time than the interval between two consecutive photometric light pulses. Preferably, no more than five said high-precision A / D conversions are provided within a single measurement cycle. More preferably, said high-precision A / D conversion is not used at all for monitoring said development of said voltage of said pulsed signal integrator during a pulse integration cycle, but only for finalizing said voltage of all A / D converters at the end of a pulse integration cycle.

[0028] Preferably, the photometric controller is provided with an integrator reset switch for synchronously resetting all pulse signal integrators before a new measurement cycle starts. After all A / D converters have converted the final voltage of the pulse signal integrator under high-precision conversion, the integrator reset switch is triggered. The integrator reset switch synchronously pulls down the voltage of all pulse signal integrators to zero, so that a new pulse integration cycle can be started.

[0029] Preferably, the integration target voltage value is at least 20% lower than the saturation voltage of the pulse signal integrator, but at least 50% of the saturation voltage. For the case of very clear water samples that cause relatively high optical and electrical pulses received by the pulse signal integrator, the integration target voltage value must be substantially lower than the saturation voltage of the pulse signal integrator. The deviation between the saturation voltage and the integration target voltage value must be higher than the highest possible pulse signal voltage of a single light pulse received by any of the detection elements.

[0030] Preferably, the photometric controller is provided with a flash counter for counting the number of flashes during a pulse integration cycle, and is provided with a maximum flash number memory storing a general maximum flash number value of flashes within a single pulse integration cycle. When the number of flashes counted by the flash counter is equal to or exceeds the stored maximum flash number, the photometric controller triggers the high-precision conversion trigger ports of all A / D converters. The general maximum number of integrated flashes defined within a measurement cycle is a fallback measurement for situations where the sample water is unexpectedly turbid or if other factors unexpectedly greatly weaken the light ultimately received by the wavelength selective detection element. In this case, the pulse integration cycle is terminated before the voltage usage of any one of the pulse signal integrators has exceeded the stored integration target voltage value. In this case, a warning signal can be generated to cause control and maintenance actions.

[0031] Preferably, the A / D converters are respectively provided with low-precision conversion trigger ports. Preferably, if the voltages of all pulse signal integrators are lower than the stored integral target value, all low-precision conversion trigger ports of all A / D converters can be synchronously triggered by the corresponding low-precision request ports of the photometric controller. The low-precision conversion of the A / D converter usually takes only a few milliseconds, so that the low-precision conversion capability of the A / D converter can be used at the beginning and / or during a pulse integration cycle to provide a prediction of the total number of photometric light pulses within a pulse integration cycle until the voltage of the first of all pulse signal integrators will exceed the stored integral target voltage value. This prediction allows the moment of the relatively time-consuming high-precision A / D conversion to be perfectly scheduled and planned at the end of the pulse integration cycle.

[0032] The technical minimum time interval between two subsequent photometric light pulses generated by the photometer flash lamp source is typically in the range of 5 ms to 30 ms, so that the low-precision conversion interval of a typical A / D converter is shorter than the flash interval and thus does not substantially affect the photometer pulse frequency.

[0033] The method claim according to the invention relates to a photometric measurement method provided by a photometric process measurement device comprising the features of one of the apparatus claims and comprising the following method steps controlled by a photometer controller:

[0034] generating light pulses with the photometer flash lamp source,

[0035] a signal integrator that monitors all pulses of the wavelength selective detection element and adapts the total number of integrated cycle pulses of a pulse integration cycle to the pulse intensity, and

[0036] An adaptive pause interval is added between the pulse integration cycles depending on the number of cyclic pulses being integrated.

[0037] Preferably, the adaptive pause interval is defined by one or more additional A / D conversion intervals.

[0038] Preferably, the measurement cycle controller selects a cycle pattern from a cycle pattern table memory according to the pulse intensity of a current pulse integration cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] An embodiment of the present invention is described with reference to the accompanying drawings, in which:

[0040] Figure 1 Schematically shows a photometric process measurement device having a photometric immersion probe head including a photometric detector device and a photometer controller,

[0041] Figure 2The schematic diagram in more detail shows Figure 1 a photometric detector device and a photometric controller, and

[0042] Figure 3a to Figure 3d The water absorption and turbidity of different samples are shown Figure 1 and Figure 2 A graph of the voltage versus time of the pulse signal integrator of the photometer controller having the highest received light pulse intensity. DETAILED DESCRIPTION

[0043] Figure 1 Schematically shows a photometric process measuring device 10 which basically consists of a land-based control unit 12 and a photometric immersion probe 20 arranged remote from the land-based control unit 12. The immersion probe 20 is arranged below the water surface 18 and is completely immersed in the water 17 of a water tank 16. The water tank 16 may be part of a wastewater treatment plant. Alternatively, the immersion probe 20 may be used in laboratory applications to continuously control water parameters.

[0044] The measuring device 10 is generally suitable for quasi-continuously photometrically determining the concentration of at least one water parameter. In the present exemplary embodiment, the photometric process measuring device 10 determines the concentration of nitrites and nitrates in the sample water 17 with a measuring frequency of a few seconds.

[0045] The photometric immersion probe 20 comprises, within a fluid-tight probe housing 22, an electronic flyback converter 30 for exciting a pulse energy capacitor 33, comprising a pulse ignition switch 36 and a photometer flash lamp source 61, which is a xenon flash lamp for providing photometric light pulses with a sufficient quasi-continuous spectrum in the ultraviolet range. The flyback converter 30 is supplied with electrical energy by the land-based control unit 12 via a power supply line 52 and comprises a converter switch 31, a transformer 32 and a blocking diode 35. The charging duration for charging a completely empty pulse energy capacitor 33 is about 5 ms to 10 ms until the voltage of the pulse energy capacitor reaches a defined ignition voltage value.

[0046] The photometric immersion probe 20 comprises a photometric detector arrangement 70 having an optical beam splitter 78 and three individual wavelength-selective detection elements 71 , 72 , 73 . Each wavelength selective detection element 71, 72, 73 includes an interference bandpass filter 71', 72', 73' and a corresponding photocell 71", 72", 73". The detection elements 71, 72, 73 detect light pulses at wavelengths of 218 nm, 225 nm and 245 nm generated by the flash lamp source 61. The 218 nm and 225 nm detection elements 71, 72 are used for direct detection of extinction / absorption caused by the nitrite and nitrate concentrations in the detected water. The 245 nm detection element 73 is a reference detector for monitoring the general composition and performance of the flash lamp source 61 and the optical path between the flash lamp source 61 and the detection elements 71, 72, 73. The photometer flash lamp source 61 and the photometric detector device 70 define a photometer device for detecting light absorption of sample water in a photometric measurement section 64, and the photometric measurement section 64 is defined between a measurement section light entrance window 65 and a measurement section light exit window 66.

[0047] The photometric immersion probe 20 includes a photometer controller 80 having: three pulse signal integrators 81', 82', 83'; three corresponding A / D converters 81, 82, 83; an integrator reset switch 86; and a measurement cycle controller 90. The pulse signal integrators 81', 82', 83' are technically capacitor elements and accumulate voltage pulses generated by the photometric detection unit 70 until the integrator reset switch 86 is closed and all pulse signal integrators 81', 82', 83' are discharged. The pulse signal integrators 81', 82', 83' have a saturation voltage Us of, for example, 2600 mV.

[0048] The three A / D converters 81, 82, 83 each have a high-precision conversion trigger port H and a low-precision conversion trigger port L. When the low-precision conversion trigger ports L of the three A / D converters 81, 82, 83 are synchronously triggered, a low-precision A / D conversion of the actual voltage of the three corresponding pulse signal integrators 81', 82', 83' is provided, which only takes about 2 ms. The low-precision conversion takes less time than the charging of the pulse energy capacitor 33.

[0049] When the high-precision conversion trigger ports H of the three A / D converters 81, 82, 83 are synchronously triggered, very accurate and high-precision A / D conversion of the actual voltage of the three corresponding pulse signal integrators 81', 82', 83' is provided by the corresponding A / D converters 81, 82, 83, which takes about 65 ms. The high-precision conversion takes more time than the charging of the pulse energy capacitor 33.

[0050] The measurement cycle controller 90 includes a reset port 91 for activating the integrator reset switch 86, a low-precision request port 92 for synchronously requesting a relatively fast low-precision A / D conversion with a short conversion time via a low-precision conversion trigger port L of the A / D converters 81, 82, and 83, and a high-precision request port 93 for synchronously requesting a high-precision A / D conversion with high precision and a relatively long conversion time via a high-precision conversion trigger port H of the three A / D converters 81, 82, and 83.

[0051] The measuring cycle controller 90 includes a flash lamp driver module 120, which controls a pulse ignition switch 36, which triggers the photometer flash lamp source 61 at a constant pulse frequency during the pulse integration cycle 204; 221; 264. The measuring cycle controller 90 also includes a flash counter 99 for counting and controlling the number FL of cyclic flashes generated by the flash lamp source 61 within one pulse integration cycle 204; 221; 264, and includes a maximum flash number memory 99' which stores a maximum flash number FLmax of 64 flashes in this embodiment.

[0052] The measuring loop controller 90 further comprises an integrated target memory 94 storing the integrated target voltage value Ut, and comprises an evaluation module 95 for continuously evaluating the digital A / D converter result related to the integrated target voltage value Ut. In the present embodiment, the integrated target voltage value Ut is 2000 mV.

[0053] The measurement cycle controller 90 further comprises a flash lamp thermal management module 130 comprising a cycle mode selection unit 98 and a dedicated cycle mode table memory 96. The cycle mode selection unit 98 including the cycle mode table memory 96 can be used as an alternative to the use of the evaluation module 95 and the integration target memory 94.

[0054] The flash lamp thermal management module 130 substantially balances the total number of photometric light pulses within the time frame F so that the total number of photometric light pulses within the time frame F is substantially constant within a tolerance of less than 3%. The flash lamp thermal management module 130 balances the number of photometric light pulses within the time frame F by adding adaptive pause intervals 303; 311 between the pulse integration cycles 204; 221; 264, which will refer to Figure 3a to Figure 3d Provide explanation.

[0055] The immersion probe 20 comprises an electronic probe controller 50 for controlling the communication between a photometer controller 80 of the immersion probe 20 and the control electronics 14 of the land-based control unit 12 via a signal line 51 .

[0056] When the photometer controller 80 starts a new frame cycle with a length of the time frame F, the pulse ignition switch 36 is electronically caused by the flash lamp driver module 120 to provide a photometric light pulse with a constant flash interval of, for example, about 20 ms generated by the photometer flash lamp source 61. After the second photometric light pulse of the new measurement cycle, the photometer controller 80 requests a low-precision conversion via the low-precision request port 91 and the connected low-precision conversion trigger ports L of all A / D converters 81, 82, 83, and determines a very rough value of the pulse intensity Ui of the single electrical pulse of the new pulse integration cycle 204; 221; 264.

[0057] The determined rough pulse intensity Ui is evaluated by the cycle pattern selection unit 98 to select a suitable cycle pattern stored in the cycle pattern table memory 96. A cycle pattern is a defined combination of a pulse integration cycle 204; 221; 264, an A / D conversion interval 100 and an adaptive pause interval 303; 311 after the A / D conversion interval 100. In the present embodiment, the cycle pattern table memory 96 stores cycle patterns with pulse integration cycles with 4, 8, 16, 21, 32 and 64 integrated pulses and an adaptive pause interval. The pause interval 303; 311 is defined by one or more additional A / D conversion intervals 101-111. The combination of the pulse integration cycle 204; 221; 264 together with the first A / D conversion interval 100 defines a measurement cycle MC.

[0058] Selection of a suitable cycle mode is always provided for the highest pulse intensity Ui of all detection elements 71, 72, 73, and it is ensured that after the last pulse of the pulse integration cycle 204; 221; 264, the integrated intensity U of at least one of the detection elements 71, 72, 73 is higher than the integrated target voltage value Ut.

[0059] Instead of selecting a suitable cycle pattern from the cycle pattern table memory 96, the length of the pulse integration cycle can be determined more accurately: the evaluation module 95 continuously compares the digital low-precision voltage value U provided by the A / D converters 81, 82, 83 with the stored integration target voltage value Ut stored in the integration target memory 94. As long as the highest digital voltage value U of all A / D converters 81, 82, 83 is lower than the stored integration target voltage value Ut, the pulse integration cycle is continued by continuing the flash action.

[0060] Once the voltage U of the first of all pulse signal integrators 81', 82', 83' has exceeded the stored integrated target voltage value Ut, the flash action is stopped and the A / D conversion interval 100 is started. After the A / D conversion interval 100, the flash lamp thermal management module 130 causes a suitable pause interval before starting the subsequent pulse integration cycle.

[0061] To provide the A / D conversion interval 100 , the photometer controller 80 requests synchronized high-precision A / D conversion via the high-precision request port 93 and the corresponding high-precision conversion trigger port H of all A / D converters 81 , 82 , 83 to determine the final digital voltage values ​​of all pulse signal integrators 81 ′, 82 ′, 83 ′.

[0062] These final digital voltage values ​​are converted into corresponding concentration values ​​of nitrite and nitrate in the sample water 17, and into corresponding device condition values. After high-precision conversion, the reset port 91 of the measurement cycle controller 90 causes the integrator reset switch 86 to reset the pulse signal integrators 81', 82', 83' to be reset to zero voltage values, so that the photometer is ready for the next measurement cycle.

[0063] Figure 3a to Figure 3d Frame cycles for different sample water absorption are shown for the detector element receiving the highest light intensity of all three detector elements 71, 72, 73. The pulse time interval ti is always constant and is about 20 ms. The high precision conversion time interval tc of a single high precision conversion interval 100 is always constant and is about 65 ms.

[0064] Figure 3a 16 identical measurement cycles MC for very clear drinking water resulting in very low overall light absorption are shown for one detector element receiving the highest light intensity. Therefore, each photometric light pulse results in a relatively high pulse voltage Ui at the corresponding pulse signal integrator 81', 82', 83'. After the third flash light source pulse, the measurement cycle controller 90 receives the integrated low-precision digital voltage value U from the corresponding A / D converter 81, 82, 83, and the cycle mode selection unit 98 selects Figure 3a A suitable cycle pattern is shown in .

[0065] The measurement cycle controller 90 stops the flashing action after the fourth pulse and causes all A / D converters 81, 82, 83 to provide high-precision conversion with a maximum converter resolution of 16 bits. After the high-precision conversion has been completed, the integrator reset switch 86 is closed to synchronously reset and fully discharge all pulse signal integrators 81', 82', 83' so that a new measurement cycle MC can be started continuously.

[0066] Figure 3b and Figure 3c A measuring cycle MC of a more turbid sample water is shown which results in a less intense single pulse voltage Ui and in a correspondingly longer measuring cycle MC. Figure 3b , Figure 3c and Figure 3d As can be seen in FIG. 1 , the cyclic pattern includes an adaptive pause interval 303 ; 311 , wherein the three or eleven A / D conversion intervals 101 - 111 define the adaptive pause interval 303 ; 311 .

[0067] Figure 3d A measurement cycle MC and the corresponding cycle pattern of a very turbid water sample with very low individual pulse voltages Ui are shown.

[0068] Typically, the measurement cycle controller 90 including the flash lamp thermal management module 130 determines and defines a complete frame cycle after the first pulse of a frame cycle. No new adjustment of the pulse integration cycle is provided before the following frame cycle.

Claims

1. A photometric process measurement device (10), comprising a photometric immersion probe (20), The photometric immersion probe (20) comprises: A photometer flash lamp source (61) for providing photometric light pulses, A photometric detector arrangement (70) comprising at least two separate wavelength selective detection elements (71, 72, 73), and a photometer controller (80) which controls the photometer flash light source (61) and the detector device (70), The photometer controller (80) comprises: A pulse signal integrator (81', 82', 83') for integrating an electric pulse with a pulse intensity (Ui) generated by the detection element (71, 72, 73) in a pulse integration cycle (204; 221; 264), a measuring cycle controller (90) for adapting the total number of integrated cycle pulses of a pulse integration cycle (204; 221; 264) to the pulse intensity (Ui) of the individual electrical pulses, A / D converters (81, 82, 83) for converting the voltage of the pulse signal integrator (81', 82', 83') in an A / D conversion interval (100) after the pulse integration cycle (204; 221; 264), a flashlight driving module (120) for controlling a pulse ignition switch (36) for triggering the photometer flashlight source (61) during the pulse integration cycle (204; 221; 264); and A flash lamp thermal management module (130) is provided for balancing the number of photometric light pulses within a time frame (F) according to the number of integrated cycle pulses, such that the total number of photometric light pulses within the time frame (F) is substantially constant.

2. The photometric process measuring device (10) according to claim 1, wherein: The flash lamp thermal management module (130) balances the number of photometric light pulses within a time frame (F) by adding adaptive pause intervals (303; 311) between the pulse integration cycles (204; 221; 264).

3. The photometric process measuring device (10) according to claim 2, wherein: The flash lamp thermal management module (130) adjusts the adaptive pause interval (303; 311) between the pulse integration cycles (204; 221; 264) so ​​that the constancy of the number of photometric light pulses within the time frame (F) is within a tolerance of 10% for all possible variations of the pulse integration cycles (204; 221; 264).

4. The photometric process measuring device (10) according to claim 2 or 3, wherein: The adaptive pause interval (303; 311) is defined by one or more additional A / D conversion intervals (101-111).

5. The photometric process measuring device (10) according to one of the preceding claims, wherein: The measuring cycle controller (90) comprises a cycle mode table memory (96), which stores different cycle modes with defined pulse integration cycles (204; 221; 264) and associated defined pause intervals (303; 311), wherein the measuring cycle controller (90) selects the cycle mode with defined pulse integration cycles (204; 221; 264) and defined pause intervals (303; 311) depending on the pulse intensity (Ui).

6. The photometric process measuring device (10) according to one of the preceding claims, wherein: The measuring cycle controller (90) comprises an integral target voltage memory (94) storing an integral target voltage value (Ut), wherein the photometer controller (80) ends the pulse integration cycle (204; 221; 264) and starts the A / D conversion interval (100) after the voltage of the first pulse signal integrator among all the pulse signal integrators (81', 82', 83') has exceeded the stored integral target voltage value (Ut).

7. The photometric process measuring device (10) according to one of the preceding claims, wherein: The photometer controller (80) is provided with a flash counter (99) and a maximum flash number memory (99'), the flash counter counts the number of flashes (FL) during the pulse integration cycle (204; 221; 264), and the maximum flash number memory stores the maximum flash number (FLmax) of the measurement cycle, and when the number of flashes (FL) counted by the flash counter (99) is equal to the maximum flash number (FLmax), the photometer controller (80) ends the pulse integration cycle (204; 221; 264).

8. The photometric process measuring device (10) according to one of the preceding claims, wherein: The integrated target voltage value (Ut) is at least 20% lower than the saturation voltage (Us) of the pulse signal integrator (81', 82', 83').

9. A photometric measurement method provided by a photometric process measuring device (10) having the features of one of the preceding claims, comprising the following method steps controlled by a photometer controller (80): A light pulse is generated by a photometer flash light source (61), all pulse signal integrators (81', 82', 83') monitoring the wavelength selective detection elements (71, 72, 73), adapting the total number of integrated cycle pulses of a pulse integration cycle (202; 221; 264) to said pulse intensity (Ui), and The number of photometric light pulses within said time frame (F) is balanced such that the total number of photometric light pulses within said time frame (F) is substantially constant.

10. The photometric method according to claim 9, wherein: The balancing is provided by adding adaptive pause intervals (303; 311) between the pulse integration cycles (204; 221; 264) depending on the number of cyclic pulses being integrated.

11. The photometric method according to claim 10, wherein: The adaptive pause interval (303; 311) is defined by one or more additional A / D conversion intervals (101-111).

12. The photometric method according to claim 9, wherein: The measurement cycle controller (90) selects a cycle mode from a cycle mode table memory (96) according to the pulse intensity (Ui) of a current pulse integration cycle (204; 221; 264).

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