DE19681587C2 - Surface tension measurement in pressurised environment - Google Patents

Abstract

The surface tension of a liquid in a vessel (1) is measured using two tubes (2,3) having a small and a large orifice in a modular probe that allows the probe to be positioned at selected and variable distances below the surface of the fluid. A high pressure source (4) provides an inert gas through a pressure regulator (5) to the input of two or three mechanical or electrical mass flow controllers (6,7,8) which control the bubble rate at each orifice. Pressure transducers (10,11) measure the pressure of bubbles from the orifices. A transducer demodulator circuit (12) converts the fluctuating pressure signal to a fluctuating DC voltage signal. Software tracks the differential waveform to capture the maximum pressure which is proportional to the surface tension.

Description

The method of maximum differential bladder pressure using two public different diameters that are immersed in the surface of a fluid was disclosed over 15 years ago as described in U.S. Patent 4,416,148 deemed adaptable for measuring in an environment under pressure or Pressure environment at nominal pressures up to 10 psig at 25 ° C. The top scorers with electronic hardware for measuring the surface tension for a Fluid with the technique of modified, maximum, differential bladder pressure was developed for Non-viscous fluids are considered sufficient as well as for fluids operating under conditions without Pressure have been checked. The hardware peak detection is on converter output signals limited, which are unipolar (positive) in value, nominally between 0 to 5 or 0 to 10 volts DC. Circuitry of the hardware peak detection detector, however triggered or triggered incorrectly at a zero crossing.

Peak detection circuits with electronic hardware have a number of other limitations when certain pneumatic conditions change the differential pressure waveform (differential pressure waveform) by generating false peaks that trigger the hardware peak detector. Hardware tip detectors can trigger incorrectly (see FIG. 4) on pressure signal fluctuations caused by capillary action when openings with an inner diameter of 0.1 mm or larger are used at the position of the small opening. As soon as the viscosity of a liquid increases, there is an increased hydrodynamic resistance of the liquid to a moving bubble. Very viscous fluids and fluids with a high concentration of suspended solids cause electronic peak value detectors to trigger incorrectly. Larger pneumatic pressures, which are required to overcome the increased hydrodynamic resistance at an opening, can cause unstable or noisy waveforms.

Lowering the amplitude of the differential pressure waveform reduces the amplitude of the fal peak values proportional, so that the peak detector with electronic hardware is no longer triggered by the wrong peak values; however, this can affect the amplitude lower the waveform in fluids with lower surface tension to the point where they no longer trigger the electronic peak detector. In this situation it is no longer possible to place the instrument in a calibration fluid of a low-point standard, such as for example to calibrate alcohol.

The peak value detector with electronic hardware also incorrectly triggers on a waveform with noisy vibrations or oscillations that result when the measured test fluid is pressurized. Flow control devices required to operate in an increasing pressure environment produce a maximum bubble pressure waveform that becomes increasingly unstable between bubbles ( Fig. 6). Large oscillations occur after each bubble is released before the system stabilizes and the next bubble is blown through.

In a non-pressurized environment, the bubble rate remains constant when the flow rate is set with flow rate monitors. In an environment with increasing pressure, however, although the maximum bubble pressure remains constant and therefore the surface tension remains constant, the bubble rate decreases with increasing pressure (goes down slowly; see FIGS. 4 and 6).

Peak detection circuitry with electronic hardware is also limited in response to various amplitude and frequency changes in the maximum bubble pressure waveform, and waveform designs change as the bubble rate changes and as the fluid viscosity increases. At one bubble per second, the waveform runs along a sawtooth configuration ( Fig. 4) where a linear, positive gradient follows the pressure increase as the bubble builds up to the point of its maximum bubble pressure. When a bubble is released, there is a sharp drop (negative downward slope) followed by an instant back pressure and capillary action before the pressure inside the tube is equalized and the next bubble begins to form. The positive slope is usually referred to as the "surface age" of the bladder, while the rest is usually referred to as "dead time" ( Fig. 5).

An ideal hardware peak detector should only include the (positive) part of the sawtooth wave readjust or track for the surface age until it reaches a correct maximum has to capture this maximum value, trigger a reset signal by detecting the after following decline (negative downward slope) and then the next correct peak additional taxes.

The dead time of a sawtooth waveform is limited and depends on the rheology of the fluid, the diameter and structure of the opening and the pressure properties of the mass flow controllers. As soon as the bubble rate increases, the dead time becomes a larger part of the time bubble interval from peak value to peak value or peak to peak. At one bubble per second ( FIG. 4), the surface age typically exceeds 90% of the bubble interval, while at 35 or more bubbles per second the surface age may be less than 10% of the bubble interval ( FIG. 5).

Volume flow controllers are set for a particular flow when one Instrument is set up and calibrated; however, the bubble rate changes as the The surface tension of the fluid changes, although the flow rate remains fixed. A top value tector must be flexible enough to cover all possible bubble areas. For example creates a flow setting, which is one bubble per second in water with a top surface tension generated in the range of 70 + dynes / cm, more than three bubbles per second in Alcohol with a surface tension typically in the range of 20 + dynes / cm. The Waveform amplitude in alcohol is due to the lower surface tension of alcohol much smaller. Electronic circuits for peak value detection are not capable ability to ignore various noise oscillations and signal combinations as described ren.

US 4,527,421 describes the method of maximum differential pressure of the bubbles ben. Here, however, a pressure drop that occurs between the opening, i. H. the point of Bla generation, and the transducer, d. H. the point of the bladder pressure measurement, not corrected.  

Summary of the invention

In the present invention is a peak detection program with modern soft Would be provided to address the problems encountered when hardware peak detection is used to solve and allow an accurate measurement of the surface tension. The resulting software program used in the present invention can, with minor hardware modifications, on the exact measurement of the surfaces voltage of viscous fluids and fluids with high solids content both in normal reverse exercise as well as under pressure conditions.

There is currently no instrument with continuous processing for surface chip removal pressure measurements on the market. There is a need for such an instrument to to measure the surface tension of pressurized, liquefied gases (to Example natural gas, freon and freon substitutes), in latex polymerization reactors and in liquids and thermoplastic materials produced under high pressure or be reworked at this.

The object of the invention is therefore a device for determining the surface chip to create a liquid regardless of the pressure environment of the container, which the liquid holds, or regardless of the immersion depth of the probes under the surface surface of the liquid.

The invention also provides a software and hardware means to the control valve of the mass flow controller to its fully open position Open to maximize the flow through the mass flow controllers hen and to clean the test heads during the time during which a boiler, a re actuator or a pipe is pressurized to reflux liquid into the test head fe and in particular to prevent fluids with a high solid concentration, the one Could cause clogging of the probes. The cleanability can also be used are used as a means to make the probes consistent during normal production cycle if necessary.

Another object of this invention is to provide a multiple converter system, so that the two sampling openings are physically decoupled and the peak values maxi paint bladder pressure can be individually averaged from each of the two opening signals. The maximum average or the maximum average of the signal from the large opening is subtracted electronically from the maximum mean of the signal from the small opening hiert to an extremely accurate maximum value of the differential bladder pressure  hen, directly proportional to the surface tension. Highly viscous fluids can the ratio of the bubble rates can be adjusted so that the surface tension value becomes independent of the viscosity effects. This is in environments with as well applicable without pressure.

Another object of the invention is the creation of a flexible, modular or construction stone-like and mechanically interchangeable means for changing the immersion length, Alignment and position of test heads for measuring surface tension, tempera tur and other similar measurements in a boiler, reactor or pipe section, namely in both normal and printing environments. This mechanical means points a porous basket at the end of the test head, which has the effect of shearing or the turbulence that would otherwise damage the free information of the bubbles at the probe openings mitigates from the flow or mixture of the fluid in the boiler, reactor or tube, while at the same time the free, non-turbulent flow of the fluid at the voltage openings and assigned temperature or other measuring probes is enabled.

The above-mentioned object is achieved in that means for automatic subsequently adjusting flow control device settings and generating dynamic surface tension curves using a sequential through flow control setting / calibration sequence are provided.

Further objects and advantages of the invention result from the following description exercise in conjunction with the accompanying drawings and claims.

Brief description of the drawings

Figure 1 is a combined pneumatic and electrical block diagram illustrating the components with the preferred embodiment of the invention using a single differential pressure transducer and two flow control devices;

Fig. 2 is a combined pneumatic and electronic block diagram similar to Fig. 1, showing the components with an alternative arrangement using two differential pressure transducers and three mass flow controllers;

Fig. 3 is a cross-sectional view of a modular probe assembly for use in boilers, reactors, or process tube sections with and without pressure showing means for using standard probes and those with interchangeable small and large openings and other process monitor probes, such as for the Temperature and conductivity; FIG. 3A is a side view of the test head of FIG. 3, and FIG. 3B is a top view of the test head of FIG. 3;

Figure 4 is a waveform diagram of a normal maximum differential bubble pressure waveform showing three different trigger signals from a hardware peak detector: a correct peak at the maximum bubble pressure point (A); a false peak at a zero crossing (B); and an incorrect peak capillary action (C);

Fig. 5 is a waveform diagram of a normal differential bubble pressure waveform at 35 bubbles per second showing surface age and dead time;

Fig. 6 is a waveform diagram of a normal waveform of maximum differential bladder pressure in water under 175 psig pressure showing the signal vibration after each bladder is released;

Fig. 7 is an idealized pressure waveform showing the normal peak and falling edge that occurs when each bubble forms and is released at an opening;

Fig. 8 is an idealized pressure waveform showing a correct and false peak due to capillary action;

Fig. 9 is an idealized pressure waveform showing the peak average of the software algorithm for peak detection and the tolerance window;

Figure 10 is a dynamic surface tension curve for two different fluids;

Fig. 11 is a system block diagram showing the processing for measuring the surface tension using the components of Fig. 1;

Fig. 12 is a system block diagram showing the process for the surface tension measurement using the components shown in Fig. 2;

Fig. 13 is a simplified software flow chart showing the overall system for software peak detection;

FIG. 14A and 14B together comprise a more detailed flow chart of the software program of the software Improvement th peak detection of the present OF INVENTION dung on;

Figures 15A and 15B together comprise a software flow diagram of the software program and routine for detecting peak signals during bubble formation, respectively;

Figure 16 is a software flow diagram for the detection of the maximum and minimum values in a detection group;

Fig. 17 is a simplified block diagram illustrating the software routine for reading for sorting values or values; and

FIG. 18A and 18B together comprise a software program for calculation of the results of measurement of surface tension.

Description of the preferred embodiment

Referring to the drawings showing a preferred embodiment of the invention, and in particular Fig. 1, an apparatus for determining the surface tension of a liquid in an environment under pressure up to 1000 psig (7000 kPa) has, but is not limited to, this , A source of high-pressure nitrogen or process gas ( 4 ), which is connected to a pressure regulator means ( 5 ) via suitable high-pressure pipes, connectors or fittings or hoses.

The invention has means to accept a source of high input pressure and to reduce the pressure as may be necessary to provide appropriate, precise control of the process gas for output mass flow to the probe assembly, with one mass flow controller per opening ( 6 , 7 ) and if necessary, a third mass flow control device ( 8 ) can be used, as used in the diagram with the two transducers ( 10 , 11 ) as shown in FIGS . 2 and 12. The mass flow control devices used in the embodiment of Invention who used the, are each a MKS model 1261, dimensioned for a constant flow rate in the range of 0-100 ml (SCCM) per minute.

The output of each mass flow control device ( 6 , 7 ), which is illustrated in FIGS . 1 and 11, is connected to a differential pressure converter or differential pressure converter ( 10 ), model DP 15, which is manufactured by the company Validyn Engineering Sales Corporation , namely via a T-piece ( 19 ); its negative (-ve) terminal is connected to the small opening side and its positive (+ ve) terminal is connected to the large opening side.

In the case of FIGS. 2 and 12, the structure for viscosity compensation with two converters, each opening is connected to the -ve connection, both + ve converter connections being connected to one another and to the third mass flow control device (MFC) ( 8 ), whereby a cross piece ( 18 ) is used and then vented to the atmosphere of the pressure reactor via an open vent fitting ( 17 ) or a third pipe.

The outputs of the surface tension device are connected to pressure pipe sections ( 20 ) that run to the reactor probe assembly, using high pressure pipe fittings ( 21 ) welded to the top of the flange ( 22 ). The flange is designed for the special boiler, reactor or process pipeline and can be used with these. The test heads with small and large openings are connected in a similar manner on the underside of the flange with similar flange welded pipe fittings ( 21 ) and hang from them and are from sections of a commercially available pipeline ( 23 ) which are graded or fraction is in fractional size, supported, typically 0.25 "or 6 mm outside diameter. These tubes are accommodated in an elongated, perforated, rigid protective tube or a protective line ( 24 ), which in a half coupling on the underside The flange is welded on, which makes it possible to vary the total length and therefore the depth of penetration of the test heads in the fluid by changing the length of the outer pipe section and the inner connecting lines in order to adapt them to special applications from the bottom and also for side installation with smaller modifi cations suitable.

A protective "basket" arrangement ( 24 ) with a closed end and ventilated or perforated, which is screwed onto the end of the protective tube section via a standard tube coupling ( 25 ), reduces the effect of shearing or turbulence from the flow or the mixing of the Fluids in the boiler, reactor or the pipe, while at the same time the free, non-turbulent flow of the fluid past the voltage openings and the associated temperature probe ( 15 ) or other measuring head is made possible. Additional inner tube spacers ( 26 ) ensure the rigidity of the system in the outer tube structure and prevent the movement of the test heads in the protective cage.

Standard pipe fittings ( 27 ) allow the replacement and replacement of, and not limited to, probes and probe materials including glass, stainless steel, coated glass, and steel, as well as straight or inverted probes. The pipe is pressure-tight, especially for temperature or other process probes to prevent fluid from entering the probes and associated electrical leads. The entire structure is modular or modular, so that it can be easily assembled and disassembled for replacement and cleaning between process or production runs.

The temperature probe ( 15 ) is provided to sense the temperature of the liquid under test because the surface tension of a liquid depends on the temperature in an inverse relationship. As soon as the temperature of the liquid rises, the surface tension decreases. An algorithm for the ratio of surface tension to temperature for two standard calibration fluids is included in the software so that during the calibration sequence the computer program reads the temperature of the calibration fluid being used and automatically enters the correct surface tension value. Typical standard calibration fluids are deionized water and ethyl alcohol. This algorithm can therefore be used to carry out temperature compensation for the surface tension values during operation.

The software program includes a sequential, automatic flow control setting / calibration sequence that allows the automatic generation of dynamic surface tension curves for tested fluids containing active surfactants ( Fig. 10). The mass flow controllers are preprogrammed to set an order of flow controller settings (ie, 10, 20, 30, 40 and 50% of the total flow for example), resulting in five different and sequentially increasing bubble rates. First, the probes are immersed in a high-point standard calibration fluid (deionized water), and the program arranges the data on the different flow settings in a step-by-step process, stopping long enough to analyze the differential pressure waveforms and automatically input the correct surface tension value to allow for the high point standard calibration fluid. This is repeated for the low point standard calibration fluid (ethyl alcohol). Different test fluids are measured sequentially at these different flow rates, and the resulting surface tension and bubble frequency data are recorded to give accurate, dynamic surface tension curves ( Fig. 10).

A power supply (PS) ( 9 ) provides operating energy to the mass flow control devices. The input and output control signals of the mass flow control device are fed with analog input and output control signals from the modulator circuits ( 12 ) of the converter, from the temperature probe ( 15 ) and from other sensors to analog input and output interface boards ( 14 ), which in the computer ( 13 ) is arranged for processing by the software program. Since there is a maximum practical distance by which the device can be removed from the test head assembly and yet the signal sensitivity and desired accuracy still remains, remote control of the device and the mass flow control devices is important in hazardous environments and those with explosive gas. A specific example is the use of the device for monitoring and controlling a polyvinyl chloride (PVC) polymerization reactor using combustible vinyl chloride gas in the reaction process. For these and similar applications, the device is mounted in an explosion-proof housing and / or in a nitrogen-cleaned closure, as may be required by local security codes and / or standards.

The device arrangement in Fig. 2 allows the correction of viscosity effects. An estimate of a fluid's hydrodynamic resistance to a moving bubble is made using Stokes' law for a viscous resistance of a liquid. The correction value to the calculated surface tension value, which is the difference between the measured value of the dynamic surface tension and the real value, is determined by the following relationship:

in which:
µ is the viscosity of the liquid,
γ is the surface tension of the liquid,
r is the radius of the opening,
τ is the surface age.

Because the change in surface tension occurs in both the large and small openings, the ratio can be reduced to a simple radius ratio of each opening and the surface age of each bubble formed. The bubble rate and therefore the surface age can be adjusted to emphasize the viscosity effect by adjusting the surface age of each opening in inverse proportion to the radii of the two openings as follows:

where r _{1 is} the radius of the small opening and r _{2 is} the radius of the large opening.

A modern peak detection software program has been developed to alleviate the problems encountered using hardware peak detection and to provide accurate surface tension measurements without false triggering of the peak detector in an environment with and without pressure, see Figs. 11 and 13. This modern and advanced program for peak detection has the means to measure the maximum bubble pressure from a demodulator output signal which can be either unipolar or bipolar (both positive, or positive and negative). It can measure fluids under pressure and can reject false peaks caused by capillary action or other oscillations. It can measure surface tension, ensure that false peaks in very viscous fluids are rejected, and correct viscosity effects, both under unpressurized and under pressure conditions.

The standard software techniques for peak detection cannot distinguish between proper peak values and those generated by noise ( Fig. 8). It was therefore necessary to develop this extension to standard software peak detection. The new, advanced software peak detection algorithm uses the average of all correct peak values to compare each new peak detected. Therefore, he has the ability to evaluate every newly recorded peak value for correct or incorrect. The user of the software is given the flexibility to influence this detection by selecting the degree to which the detected peak values are accepted as correct.

The system consists of two main parts, which are in turn divided into sub-systems (FIG. 13-FIG. 18). The two main parts are: (1) differential pressure signal analysis and (2) differential pressure signal peak value detection.

Immediately after starting the program or when the probes are inserted into a new sample no average is available with which the recorded peak values are compared could become. Therefore the signal must be analyzed, i. H. the standard software Peak detection is used to detect a certain number of peaks. With these peak values, the correct average can be determined and is determined by the used at this point in the modern peak detection algorithm.

The differential pressure signal is represented in the computer by individual integers, see FIGS. 14A and 14B. Eight consecutive numbers result in a detection or recognition group, see FIG. 16. Outside each recognition group, the maximum and minimum values are determined, and their indices are also stored in the memory. The maximum values are used to detect peak values in this algorithm in the method described below.

To detect a peak, the falling edge of the differential pressure signal must first be detected. A falling edge ( Fig. 7) is defined by:

• 1. The difference between the maximum and the minimum value must be greater than 366 mV (+150 integer) to avoid capturing noisy peaks the.
• 2. The guideline number or the index of the minimum value must be higher than the index of the Ma ximal values, d. H. the minimum value must be after the maximum value in the same entry group appear.

The maximum value outside the current detection group is compared with the maximum value outside the previous detection group. This is an important step and a unique feature of this algorithm during peak detection because the peak may appear in detection group I ( Fig. 7) but the falling edge is detected in detection group II. By using this condition, it is confirmed that a most accurate peak is provided by the peak detection algorithm.

During signal analysis, the software tries to detect a certain number of peaks, see Figures 15A and 15B. This number depends on the settings of the tolerance window. The relationship between the setting of the tolerance window and the number of analysis peak values is:
Tolerance window ENG (NARROW) - 10 peak values
MEDIUM tolerance window - 16 peak values
WIDE tolerance window - 20 peaks

After the necessary number of peak values has been recorded and stored, the peak values are sorted in terms of value, in this case using the bubble sorting algorithm ( FIG. 17). This algorithm is not limited to a sorting process. After sorting, the highest value in the analysis series is at the top in the buffer, the lowest at the bottom.

example

After the values have been sorted, the five highest values (index 5 to 9) become the rich peak average calculated. Regardless of the setting of the tolerance window the five highest values are always used for the average calculation. This guides derives from a differential pressure signal, which consists of correct peak values and spit capillary effects (incorrect peak values). This case can be considered the worst viewed because there is an even number of correct highs point peak values and incorrect, low point peak values. By considering only the The upper part of the analysis series only shows the correct peak values for the averages calculation used. This concludes the analysis.

During modern peak value recording, after a peak value has been recorded, there must be a further check of this value in order to evaluate whether it is correct under the current circumstances. This rating makes this peak detection algorithm modern, see Figures 14A and 14B.

The recorded peak value is compared with the running average of all previously correct peak values. A tolerance window is used for this comparison. In order to compare the recorded peak value with the current average peak value, the absolute value of the difference between the peak value and the peak average value must be smaller than the tolerance value:
ABS (peak_value - peak_average) (peak value - peak value average) <= tolerance value

If the result of this equation is true, the peak value can be accepted as correct become. In this case the new result can be calculated for the surface tension become.

The user-adjustable tolerance window is a very unique feature of this software, see Fig. 8 and 9. With this window two things are now possible:

• 1. Peak values caused by capillary action can be rejected so that they have no effect on the results of the surface tension.
• 2. It is possible to measure high viscosity fluids, which are typically incompatible diffe have profitable pressure signals.

Peak values caused by capillary action typically have a peak value which is approximately 20% of the peak value which appears when a bubble is released ( FIG. 8).

With a standard peak detection algorithm, these two peaks cannot be distinguished, which leads to incorrect results of the surface tension and also the bubble frequency. With the modern peak value detection using the tolerance window, peak values can be distinguished or differentiated ( FIG. 9). The tolerance window is a value range of ± the tolerance around the peak average. The correct peak value, which is within the tolerance window, can be accepted while the capillary action is rejected or rejected.

In order to measure fluids with high viscosity even using the basic device ( Fig. 1), the user can set this tolerance window to:

narrow (± 300 mV)

medium (medium) (± 650 mV)

wide (± 1000 mV)

Because the averages of the fluids are typically more than those of a non-viscous fluid fluctuate, the user can determine which with the adjustable tolerance window  Peak values are accepted, resulting in a very accurate result for viscous fluids leads. In addition, the average factor for the resulting calculation is wide ren tolerance windows increased so that even with fluctuating peak values a high Stability of results can be expected.

A new averaging algorithm used in this software achieves two goals: (1) greater stability of results compared to moving averages; and (2) faster new average calculation, see Figures 18A and 18B.

The averaging factor is introduced for this averaging algorithm. The averaging or the average of a certain result (either surface tension, temperature or bubble frequency) is calculated by:

The relationship between the tolerance window setting and the number of analysis peaks is:
Tolerance window ENG (NARROW) - averaging factor = 10
Tolerance window MEDIUM - averaging factor = 21
WIDE tolerance window - averaging factor = 33

While the shape of the device described here is a preferred embodiment represents this invention, it is understood that the invention to this precise form of the pre direction is not limited and changes can be made, without departing from the scope of the invention as set forth in the appended claims is defined.  

Explanation of FIGS. 11 to 18B Fig. 11

11-1

Cleaning the MFC's (the mass flow controllers = mass flow controllers) (if necessary)

11-2

Setting the MFC's

11-3

Set bubble rate

11-4

demodulator output

11-5

Analysis of the differential pressure signal

11-6

Setting tolerance window; ENG (NARROW) = 10 peaks, MEDIUM (MEDIUM) = 16 peaks, WIDE (WIDE) = 20 peaks

11-7

Read the temperature

11-8

Program recognizes 10, 16 or 20 peak values; Sort peak values; Hold highest values

11-9

Reject the lowest values (wrong peaks)

11-10

Display demodulator output waveform

11-11

Modern peak value detection; Comparison with average

11-12

Reject incorrect peak values

11-13

Keeping the right peak

11-14

Calculate the bubble interval

11-15

Calculate reversal of the bubble interval

11-16

Reverse ratio of surface tension to temperature

11-17

Calculate temperature-compensated surface tension

11-18

Display surface tension

11-19

Bubble interval display

11-20

Display temperature

11-21

Bubble frequency display

Fig. 12

12-1

Clean MFC's (if necessary)

12-2

Setting the MFC's

12-3

Set bubble rate

12-4

Set bubble rate

12-5

Demodulator output signal # 1

12-6

Analysis of the differential pressure signal

12-7

Setting tolerance window; NARROW = 10 peaks, MEDIUM = 16 peaks, WIDE = 20 peaks

12-8

Demodulator output signal # 2

12-9

Analysis of the differential pressure signal

12-10

Setting the tolerance window; NARROW = 10 peaks, MEDIUM = 16 peaks, WIDE = 20 peaks

12-11

Read the temperature

12-12

Detect 10, 16 or 20 peaks; Sorting the peak values; Keep the highest values

12-13

Reject the lowest values (wrong peaks)

12-14

Capture of

10

.

16

or

20

Peak values; Sorting peak values; Keep the highest values

12-15

Reject the lowest values (wrong peaks)

12-16

Modern peak value acquisition; Comparison with average

12-17

Rejecting incorrect peak values

12-18

Modern peak value acquisition; Comparison with average

12-19

Rejecting incorrect peak values

12-20

Display demodulator # 1 output waveform

12-21

Keeping the right peak

12-22

Display demodulator # 2 output waveform

12-23

Keeping the right peak

Figure 12A

12-24

Calculate the differential of correct peak values

12-25

Calculate the bubble interval

12-26

Calculate the bubble interval

12-27

Inverse ratio of surface tension to temperature

12-28

Calculate the temperature compensated surface tension

12-29

Calculate the inversion of the bubble interval

12-29

a Calculate the inversion of the bubble interval

12-30

Display surface tension

12-31

Bubble interval display # 1

12-32

Bubble frequency display

12-33

Bubble frequency display

12-34

Bubble interval display # 2

12-35

Display temperature

Fig. 13

13-1

overall view

13-2

Complete system for software peak value acquisition

13-3

Acquisition of peak values with any standard software peak value acquisition

13-4

Not enough peaks found for analysis

13-5

Analysis of peak values and calculation of peak value average

13-6

Acquisition of peak values with the improved software peak value acquisition and display results

13-7

Sampling is a

Figure 14A

14-1

Software peak value acquisition task modern peak value acquisition

14-2

Set the current peak counter on the screen to zero

14-3

First review capture group

14-4

Yes

14-5

No

14-6

Initialization of auxiliary variables for min / max procedures

14-7

Switch on channel # X display

14-8

Yes

14-9

No

14-10

Convert integer value from channel #X to volts

14-11

Store voltage value in data series for scanning graphical display

14-12

Save - 10 V in data series for scanning graphical display

14-13

Refreshing the display Scanning graphically with current data

14-14

Min / max detection

14-15

Procedure for finding minimum / maximum values in a detection group

14-16

Difference between running maximum and minimum greater than

150

and index of the minimum greater than index of the maximum (finding gradient I)

14-17

Yes

14-18

No

Figure 14B

14-19

Yes

14-20

Peak value appeared in the previous data acquisition group (previous maximum value larger than current)

14-21

Yes

14-22

No

14-23

Set lost maximum value equal to the running maximum value

14-24

Set lost maximum value index equal to running maximum value index

14-25

Reset of variables used in the min / max procedure

14-26

Convert integer value of the current maximum value into volts

14-27

Running maximum value within tolerance window

14-28

Yes

14-29

No

14-30

Increase in sample number to the correct peak value

14-31

Increase in peak value counter in the current sampling interval

14-32

Calculate result

14-33

Calculate the result depending on the parameter. Here: surface tension

14-34

Calculate result

14-35

Calculate the result depending on the parameter. Here: temperature

14-36

Refresh "Real Time Results" window

14-37

Data logging or print selection

14-38

Yes

14-39

No

14-40

Execution of selected data recording task (s)

14-41

Calculate result

14-42

Calculate the result depending on the parameter. Here: bubble frequency

14-43

Refresh "bubble data" window

Figure 15A

15-1

Software Analysis Sawtooth Peak Acquisition for Analysis

15-2

Set running peak counter on screen to zero

15-3

First check in the data entry group

15-4

Yes

15-5

No

15-6

Initialization of auxiliary variables for min / max procedures

15-7

Convert integer value of all channels to volts

15-8

Store voltage values in data series for scanning graphical display

15-9

Refresh scanning graphical display with current data

15-10

Min / max detection

15-11

Procedure for finding minimum / maximum values in a detection group

15-12

Difference between running maximum and minimum greater than 150 and index of the minimum greater than index of the maximum (find gradient!)

15-13

Yes

15-14

No

Figure 15B

15-15

Yes

15-16

No

15-17

Peak value, appeared in the previous data entry group (previous maximum value greater than current)

15-18

Yes

15-19

No

15-20

Setting the last maximum value equal to the running maximum value

15-21

Set the last maximum value index equal to the maximum value index running

15-22

Reset auxiliary variables that are used in the min / max method

15-23

Convert integer value of the current maximum value into volts

15-24

Store the volts value of the current maximum value in the analysis series

15-25

Store the volts value of the current temperature value in the analysis series

15-26

Increase peak value counter to recorded peak value

15-27

Refresh "Real time result" window with current value of the peak value counter

15-28

Necessary number of recorded peak values

15-29

Yes

15-30

No

15-31

Sort peak amplitudes

15-32

Sort values by size in the special analysis series. Here: amplitude peak

Figure 15C

15-33

Sort peak amplitudes

15-34

This method is also used for sorting temperature values. Here: temperature values

15-35

Compute average

15-36

Average the top five values in the special analysis series. Here: peak amplitudes

15-37

Compute average

15-38

Average the top five values in the special analysis series. Here: temperature values

15-39

Initialize bubble frequency with value =

1

to avoid errors divided by zero runtime

Fig. 16

16-1

Min / max detection method for finding minimum / maximum values in a detection group

16-2

Pressure value at a pressure index higher or equal to the maximum running

16-3

Yes

16-4

No

16-5

Setting the running maximum value is equal to the pressure value at the pressure index

16-6

Set running maximum value index equal to pressure index

16-7

Pressure value with pressure index higher or equal to the minimum running

16-8

Yes

16-9

No

16-10

Set running minimum value equal to pressure value at pressure index

16-11

Set running minimum value index equal to pressure index

16-12

Convert temperature index integer value to volts before index increases

16-13

Increased indices due to the number of scanned channels

16-14

Increase in the number of points analyzed in the detection group

16-15

Increase index of data buffer

16-16

Increase in the number of samples on each sample point to calculate the time interval

16-17

While not eight points are analyzed

Fig. 17

17-1

Sort peak amplitudes

17-2

Sort amplitudes by size in a special analysis series using the bubble sorting method

Figure 18A

18-1

Calculate result Calculate result depending on the parameter

18-2

Software surface tension

18-3

Multiply the current peak average by the averaging factor

18-4

Add voltage value according to the current voltage value to the result

18-5

Set new peak average equal to the peak average divided by the averaging factor plus 1

18-6

Convert new average from voltage value to integral value

18-7

Calculate new surface tension with calibration values

18-8

Hardware surface tension

18-9

Multiply current surface tension average by averaging factor

18-10

Add the tension value corresponding to the current surface tension value to the result

18-11

Set a new surface tension average equal to the surface tension average divided by the averaging factor plus 1

18-12

Convert new average from volts to integral

18-13

Calculate new surface tension with calibration values

Figure 18B

18-14

calculation type

18-15

temperature

18-16

Multiply current temperature average by averaging factor

18-17

Add voltage value according to the current temperature values to the result

18-18

Set a new temperature average equal to the temperature average, divided by the averaging factor plus 1.

18-19

Convert new average from voltage value to integral value

18-20

Calculate new temperature with calibration values

18-21

bubble frequency

18-22

Peak counter equals zero

18-23

Yes

18-24

No

18-25

No peak values found, set counter to bubble frequency to avoid runtime errors divided by zero

18-26

First acquisition process after analysis

18-27

Yes

18-28

No

18-29

Set bubble frequency equal to peak counter divided by scan length

18-30

Multiply current peak average by averaging factor

18-31

Add the result of the peak counter divided by the sample length

18-32

Set the new bubble frequency equal to the bubble frequency average, divided by the averaging factor plus 3.

Claims (11)

1. Device for determining the surface tension of a liquid with one or more test specimens with openings of different diameters, which are arranged under the surface of a liquid in a boiler, reactor or section of a process line;
Means for adjusting the depth of immersion of the openings in the liquid;
Means for creating a gas pressure source for the pipes using a separate mass flow controller for each test specimen;
Means connected between the gas source and the test pieces for creating a regulated, constant volume flow rate of the gas to the test pieces;
Means for controlling the gas flow to the test specimens and therefore the bubble rate at the openings;
Means for measuring the difference in the maximum pressures of the bubbles which form on the test heads as a function of the surface tension of the liquid using a differential pressure transducer;
Means for automatically measuring the temperature of a standard calibration fluid and calculating the corrected temperature compensated surface tension value;
Means for automatically adjusting flow control device settings sequentially and generating dynamic surface tension curves using a sequential flow control setting / calibration sequence. 2. Device for determining the surface tension of a liquid with
a boiler, reactor or process piping system for receiving a liquid under pressure according to claim 1, characterized in that a pair of test specimens with openings of different diameters, which are arranged under the surface of the liquid in the boiler, reactor or piping system;
Means connected between the gas source and the test pieces for creating a regulated, constant volume flow rate of the gas to the pipes regardless of the pressure within the boiler, the reactor or the piping system; and
Means for automatically controlling the gas flow to the test specimens and therefore the bubble rate of the gas at the openings are provided, regardless of the pressure inside the boiler, reactor or piping system. 3. Device for determining the surface tension of a liquid according to claim 2, characterized in that
Means for creating a gas source under pressure to the pipes using a separate mass flow controller for each pipe and a third Steuerge device, which is vented to the boiler atmosphere or a third pipe to offset the pressure within the boiler, reactor or piping system, and
Means for measuring the maximum differential pressure of the bubbles formed on the probes as a function of the surface tension of the liquid using two or more differential pressure transducers, one common side of which is connected to the pressurized system within the boiler, reactor or piping system is provided. 4. Modular probe assembly for immersion in a boiler, reactor or from a process pipeline
Means for mounting standard surface tension probes made from, but not limited to, various materials including glass, stainless steel, coated materials;
Means for mounting standard surface tension probes made in different configurations including straight, curved or vice versa;
Means for changing the vertical and horizontal penetration and therefore a depth of immersion of the probe assembly by changing or eliminating the lengths of the center connecting portions of the inner tubing and outer tubing sections;
Means for mounting a temperature probe in the vicinity of sensing probes for surface tension within an outer protective tube assembly;
Means for mounting probes for other chemicals in the vicinity of the surface tension openings within an outer protective tube assembly, including, but not limited to, conductivity probes;
Means for allowing fluid to flow from the bulk volume of the boiler, reactor or process line section through the walls of an inner probe assembly with external protection while mitigating shear and turbulence from the bulk fluid;
Means for pressure sealing the test heads and related electrical test head lines against the ingress of liquid or gas into the pipes from within the boiler, reactor or the process pipeline. 5. Device for determining the surface tension of a liquid with
Means for automatically controlling the bubble rate through a tube immersed in a vessel, reactor or section of a process line regardless of the pressure within the vessel, reactor or tube or the immersion depth;
Means for cleaning the pipe during start-up and operation;
Means for measuring the maximum bladder pressure signal from a demodulator output circuit which can be either unipolar or bipolar;
Means for measuring the maximum bladder pressure and therefore the surface tension of a liquid with possibilities for rejecting incorrect peak values which are caused by capillary action, regardless of the pressure environment of the liquid;
Means for measuring the maximum bladder pressure and therefore the surface tension of a liquid with means for rejecting false peaks caused by oscillations in the waveform of maximum bladder pressure independent of the pressure environment of the liquid;
Means for measuring the surface tension in a viscous fluid with means for rejecting incorrect peaks due to fluctuations in the differential pressure waveform caused by the hydrodynamic resistance of the viscous fluid to bubbles formed at the orifice;
Means for automatically measuring the temperature of a standard calibration fluid and selecting the correct temperature-compensated surface tension value;
Means for automatically adjusting settings of the flow controllers and generating dynamic surface tension curves using a sequential flow control setting / calibration frequency. 6. Device for determining the surface tension of a liquid with
Means for automatically controlling the bubble rate through two tubes submerged in a boiler, reactor or section of a process tube, regardless of the pressure within the vessel, reactor or tube or the immersion depth of the tube;
Means for cleaning the pipes during start-up or operation;
Circuitry for measuring maximum bubble pressure signals from demodulator output circuits, which can be either unipolar or bipolar;
Means for measuring the maximum bladder pressure and therefore the surface tension of a liquid with measures for rejecting incorrect peak values which are caused by capillary action, regardless of the pressure environment of the liquid;
Means for measuring the maximum bladder pressure at an opening and mean peak values, which are caused by oscillations in the waveform maxima len bladder pressure in a pressure environment and therefore determining the surface tension of the liquid;
Means for measuring surface tension in a viscous fluid, including measures to reject false peaks due to fluctuations in the differential pressure waveform caused by the hydrodynamic resistance of the viscous fluid to a bubble formed at the opening;
Means for automatically measuring the temperature of a standard calibration fluid and calculating the correct temperature compensated surface tension value;
Means for automatically adjusting flow controller settings sequentially and generating dynamic surface tension curves using sequential flow control setting / calibration sequences. 7. Device for determining the surface tension of a liquid with
Means for automatically controlling the bubble rate through two or more pipes with different opening sizes immersed in a vessel, reactor or section of a process line, regardless of the pressure in the vessel, reactor or tube or the depth of immersion in the liquid;
Means for cleaning the pipes at all times during start-up and operation;
Circuitry for measuring the maximum bladder pressure signals from demodulator output, which can be either unipolar or bipolar;
Means for measuring the maximum bladder pressure and therefore the surface tension of a liquid with measures for rejecting incorrect peak values which are caused by capillary action, regardless of the pressure environment of the liquid;
Means for measuring the maximum bubble pressures independently at two openings and for rejecting incorrect peak values, which are caused by oscillations in the waveforms of maximum bubble pressure in a pressure environment, with means for subtracting the resulting maximum bubble pressure values in order to determine the difference or the differential and thereby to determine the surface tension of the liquid;
Means for measuring the maximum bubble pressure independently at each of two openings in a viscous liquid and means for adjusting the flow rates at each opening in a ratio which abolishes the effect of the hydrodynamic resistance of the viscous fluid to bubbles formed at the openings ;
Means for automatically measuring the temperature of a standard calibration fluid and selecting the correct temperature-compensated surface tension value;
Means for automatically adjusting flow controller settings sequentially and generating dynamic surface tension curves using a sequential flow control setting / calibration sequence. 8. Probe assembly for sensing the surface tension of a liquid with
an elongate rigid tube provided with a collar at one end for attachment to a mechanism for supporting the probe assembly in a boiler;
at least two pressure pipes extending the length of the rigid pipe, one extending through the collar and fitted with a fitting;
a test head attached to the other end of each pressure tube, each test head having a calibrated opening at its end;
a basket attached to the other end of the rigid tube and having a solid bottom and a plurality of openings on its side to allow the free, non-turbulent flow of the fluid past the calibrated openings of the probes during the Effect of shear or turbulence from the flow or the mixing or mixture of the eluent in the boiler is alleviated. 9. probe assembly according to claim 8, further comprising a temperature probe, which in is arranged within the rigid housing and to the height of the calibrated opening extends. 10. The probe assembly of claim 8, further comprising spacers between the Pressure pipes and the rigid pipe are arranged. 11. The probe assembly of claim 8, wherein the rigid tube is perforated.