CA1077738A - Monitoring particulate solid flow in a conduit using a temperature sensitive electrical resistance device - Google Patents
Monitoring particulate solid flow in a conduit using a temperature sensitive electrical resistance deviceInfo
- Publication number
- CA1077738A CA1077738A CA267,462A CA267462A CA1077738A CA 1077738 A CA1077738 A CA 1077738A CA 267462 A CA267462 A CA 267462A CA 1077738 A CA1077738 A CA 1077738A
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- flow rate
- direct current
- resistance device
- temperature sensitive
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/10—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables
- G01P5/12—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables using variation of resistance of a heated conductor
Landscapes
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
ABSTRACT
Apparatus for monitoring the flow of particulate solids in a conduit in which the 'noise' voltage in the electrical output from a thermistor in thermal contact with the stream of particulate solids, are utilised to operate signalling means. Longer term variations in the electrical output from the thermistor due to process variations are filtered out.
The apparatus may be adapted to detect a fall in the solids flow rate below a particular limiting value by the use of a comparator stage or may be adapted to give an instantaneous indication of flow rate by utilising a direct current output to drive for example a moving coil meter.
Apparatus for monitoring the flow of particulate solids in a conduit in which the 'noise' voltage in the electrical output from a thermistor in thermal contact with the stream of particulate solids, are utilised to operate signalling means. Longer term variations in the electrical output from the thermistor due to process variations are filtered out.
The apparatus may be adapted to detect a fall in the solids flow rate below a particular limiting value by the use of a comparator stage or may be adapted to give an instantaneous indication of flow rate by utilising a direct current output to drive for example a moving coil meter.
Description
` ~7~7738 This invention relates to a method and ap~aratus for monitoring the flow of a stream of particulate solids in a conduit.
Temperature sensitive electrical resistance devices, such as thermistors, may be used -to monitor the flow of a stream of a gas or liquid i.n a conduit by utilising the overall e~fect of cooling or heating of the resistance dovice by the stream of gas or liquid in thermal contact with it to produce a corresponding effect on the resis-tance of the device and thus on the level of a currentflowing in it. A variation in the rate of flow will produce a c~rresponding variation in the degree of cool:Lng I or heating and this may be detected by monitoring the level of current leaving the resistance device by means of a suitable signalling device.
. Such an arrangement may give a satis~actory indication of a large variation in flo~ rate. Where the ~low rate to be monitored is low the degree of cooling or heating of the resistance device may be so lo~ as to render the resulting variati.on in current difficult to distinguish from tha-t caused by natural variations of the temperature of the gas or liquid or by variations in other operating conditions.
To obtain an accurate indication of flow rate, or to obtain :. a fast response indication of cessation of flo~ in such circumstances, an elaborate system of sensing devices and other equipment is required to enable interfering variables such as variations in the current fed into the resistance device and in the temperature of ~he gas or liquid to be~
:''. .: , . : .
.,., ..
identified and compensated for, before the final signal is generated.
When a stxeam of particulate solids flows in a conduit, such as a pipe or a suitable trough within which an object is placed in the path of the stream, a limited number of discrete particles are in contact with the object at any time. We have found that their varying sizes and heat transfer characteristics cause changes in the ability of the stream to effect heat ex-change with the object at a high frequency having a relationship to the frequency of collision with the object by the particles and that if the object is a temperature sensitive electrical resistance device having a current flowing through it these changes in ability to conduct heat exchange manifest themselves as high frequency variations in the signal voltage from the resistance device, hereafter called "noise voltages". As in the case of a temperature sensitive electrical resistance device used to monitor the flow of a stream of gas or liquid, the signal from the resistance device will also reflect relatively l lower frequency alterations in operating conditions affecting the performance of the resistance device such as variations in the voltage supplied to the device and the mass temperature of the stream; which operating conditions have previously, in monitoring gas or liquid flow, been compensated for; and the mass flow rate of the-stream; which operating condition has previously, in monitoring gas or,liquid flow, been measured by refexence to the overall level of current.
The "noise voltage" frequencies may be in the subaudio frequency range i.e. below 30Hz.
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77~3 According to one aspect of the present invention, there is provided apparatus for monitoring the flow of a stream of particulate solids in a conduit comprising a temperature sensitive electrical resistance device and, in electrical connection with said device, a differentiator for providing a differentiated voltage output proportional to the rate of change of an input voltage from the temperature sensitive electrical resistance device thereby to respond to noise voltages therein and to attenuate lower frequency vari-ations in the input voltage, a rectifier for converting the differentiated voltage output into a direct current output voltage, a filter circuit for attenuating residual components in the direct current output voltage thereby to produce a filtered direct current voltage the magnitude of which is in-dicative of the flow rate of the stream, and a comparator connected to the filter circuit for comparing the direct current voltage with a reference voltage to derive an error signal indicative of the deviation of the actual flow rate from a predetermined flow rate.
According to another aspect of the present invention, there is provided a method for monitoring the flow of a stream of particulate solids in a conduit comprising causing the stream to be in thermal contact with a temperature sensitive electrical resistance device connected to a d.c. volt-age source thereby to generate a voltage signal, differentiating the voltagesignal to give a differentiated voltage output proportional to the rate of change of the voltage signal thereby to respond to noise components in the voltage signal and to attenuate lower frequency components, rectifying and filtering the differentiated voltage output thereby to produce a filtered direct current voltage the magnitude of which is indicative of the flow rate of the stream and comparing the direct current voltage with a reference voltage to derive an error signal indicative of the deviation of the actual . ~ . . .
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.
flo~ rate from a predetermined flow rate.
A suitable temperature sensitive electrical resistance device for use in the operation of this invention is a thermistor. The electrical out-put from the temperature sensitive electrical resistance device may be passed through one or more diferentiation amplification, rectification and filtra-tion stages. More particularly the current from the resistance device may be amplified by amplifying stages, working over the "noise voltage" frequency range and capable of rejecting relatively lower `' ., :` ~
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~37773~3 frequencies due to alterations in the operating conditions affecting the performance of the resistance device. The amplified "noise voltages" may be rectified and filtered to provide a direct current voltage which may be used to operate alarm, control or indicating circuits.
The present invention makes the use of equipment designed to identify, and compensate for, interfering variations in operating conditions, such as variations in the mass temperature of a particulate solid, unnecessary and provides a remarkably simple monitoring means.
The invention is particularly suitable for use as a warning of stoppages in the flow of particulate solids. When the flow stops the "noise vol~agesl~ cease and the current derived there-from drops to zero~ The signalling means may be arranged to respond, either instantaneously or after a specified delay period, so as to ignore brief interruptions, either when the current passes a specified minimum value or completely ceases.
It is a further advantage of the invention that an interruption of the electric supply to the resistance device also causes a response from the signalling means, the whole system thus being "fail safe".
According to a modification of the invention the frequency and amplitude of the "noise voltages" may be monitored to give a measure of the flow rate either additionally to, or instead of, flow interruptions.
:
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~777313 .
The particular equipment utilised in the practice of this invention including the type of therrnistor, if used, and its housing, and the frequency pass-band of the amplifying circuits, may be selected and adjusted to give the best results bearing in mind the identity of the particulate solid and range of its flow rate which it is desired to monitor.
: The method of apparatus of this invention may be used 1to monitor the flow of flowable particulate solids comprising a mixture of particulate materials. The presence of a liquid is not excluded provided that the solid/ particles are distributed throughout the liquid as in a slurry. Examples of suitable flowable particulate solids are powdered coal, sugar, sand, metal powders, inorganic oxides such as titanium dioxide and ground ores such as ground ilmenite ore. Suitably the particulate solid has a largest particle diameter of not more than ~ inch and will not pass a 200 mesh British Standard Sieve. Suitably the conduit has a diameter of,for ex~mple, from 2 to 6 inches.
`An example of a flow monitoring system according to the invention will now be described with reference to the accompanying drawing which is a circuit diagram of the system.
The system comprises a glass encapsulated thermistor 1 arranged, in use, for thermal contact with a flow of particulate solids, connected to a direct current electrical supply, preferably of from 5 to 25 volts, through a resistor 2 preferably having a value of from 250 to 500 ohms. The signal output from the thermistor, comprising "noise voltages"
and relatively lower frequency voltage variations due to changes in operating conditions, is connected through circuitry com-prising a differentiator 5 including a resistor 3 and capacitor ~, an alternating current amplifier 6, a rectifier 7, a filter 8 and a comparator 9. The differentiator 5 comprises an operational amplifier 10 and its associated input and feed back circuit components and gives an output voltage which is proportional to the rate of change of the input voltage.
lQ Low frequency voltage variations in the signal are therefore automatically attenuated. The alternating current ampllfier 6 comprises an operational amplifier 11 with its associated input and feed back circuitry and provides a voltage gain, preferably of from 5 to 15, at the frequencies of interest, that is the "noise voltage" frequencies which are generally helow 30Hz and may very suitably ~e in the range of 1 to lOHz.
The differentiated and amplified "noise voltages" are then passed to a rectifier 7 which gives a direct current output which is passed through a filter circuit 8 comprising capacitors 12 and 13 and resistor 1~ and the residual components are thereby attenuated. The resulting relatively pure direct current voltage is passed to a comparator 9 which comprises an operational amplifier 15 and associated circuitry and which compares it with a reference direct current voltage prefer-ahly of from 0.1 to 0.5 volts. If the voltage applied to the comparator exceeds the reference voltage the comparator output is negative and if the voltage applied to the com-parator falls below the reference voltage the comparator :, . -, .
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output is positive. The comparator output is connected to signalling means 16 operated by a change from negative to positive in the input current.
A modification of the equipment described above may be used to give an indication of flow rate. A similar circuit arrangement as that shown in the attached drawing may be used up to the output of the amplifier 6, although some of the component values may be changed. The voltage at this point depends mainly upon the rate of change of the thermistor "noise voltage", and this in turn is related to the velocity of the moving particles. The voltage at this point may be fed into a full-wave bridge rectifier circuit, and the direct current output, after suitable filtering, may be used to drive a moving coil meter. The deflection of the meter is approximately proportional to the flow rate of the particulate solid.
Example ( The system illustrated in the accompanying drawing was used to monitor a flow of sand having an average particle size of 700 microns and a particle size of from 300 microns to 1500 microns falling through a vertical pipe of 4" dia.
under gravity. The thermistor was mounted on an end of a supporting tube which projected radially through the wall .. , of the pipe and supported the thermistor at the axis of the pipe. With reference to the description and drawing of the apparatus use~ the direct current input to the thermistor was 15 volts and the resistor 2 had a value of 390 ohms.
..
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.~ .
The amplifier was selected to give a voltage gain of about 9.5 in the frequency band of l Hz to 10 Hz, which was the "noise voltage" frequency band for flow rates of up to 300 lbs/hr of sand. The amplitude of these voltages was from about 20 to 200m~. The reference voltage used ! in the comparator stage was 0.3 volts.
The pipe was provided with a valve to enable the flow rate to be varied artificially from zero to 300 lbs/hr.
When the rate was allowed to fall to below 15 lbs/hr, and only then, the signalling means was activated.
' . . ' ', ' ,:
~ , .
.
Temperature sensitive electrical resistance devices, such as thermistors, may be used -to monitor the flow of a stream of a gas or liquid i.n a conduit by utilising the overall e~fect of cooling or heating of the resistance dovice by the stream of gas or liquid in thermal contact with it to produce a corresponding effect on the resis-tance of the device and thus on the level of a currentflowing in it. A variation in the rate of flow will produce a c~rresponding variation in the degree of cool:Lng I or heating and this may be detected by monitoring the level of current leaving the resistance device by means of a suitable signalling device.
. Such an arrangement may give a satis~actory indication of a large variation in flo~ rate. Where the ~low rate to be monitored is low the degree of cooling or heating of the resistance device may be so lo~ as to render the resulting variati.on in current difficult to distinguish from tha-t caused by natural variations of the temperature of the gas or liquid or by variations in other operating conditions.
To obtain an accurate indication of flow rate, or to obtain :. a fast response indication of cessation of flo~ in such circumstances, an elaborate system of sensing devices and other equipment is required to enable interfering variables such as variations in the current fed into the resistance device and in the temperature of ~he gas or liquid to be~
:''. .: , . : .
.,., ..
identified and compensated for, before the final signal is generated.
When a stxeam of particulate solids flows in a conduit, such as a pipe or a suitable trough within which an object is placed in the path of the stream, a limited number of discrete particles are in contact with the object at any time. We have found that their varying sizes and heat transfer characteristics cause changes in the ability of the stream to effect heat ex-change with the object at a high frequency having a relationship to the frequency of collision with the object by the particles and that if the object is a temperature sensitive electrical resistance device having a current flowing through it these changes in ability to conduct heat exchange manifest themselves as high frequency variations in the signal voltage from the resistance device, hereafter called "noise voltages". As in the case of a temperature sensitive electrical resistance device used to monitor the flow of a stream of gas or liquid, the signal from the resistance device will also reflect relatively l lower frequency alterations in operating conditions affecting the performance of the resistance device such as variations in the voltage supplied to the device and the mass temperature of the stream; which operating conditions have previously, in monitoring gas or liquid flow, been compensated for; and the mass flow rate of the-stream; which operating condition has previously, in monitoring gas or,liquid flow, been measured by refexence to the overall level of current.
The "noise voltage" frequencies may be in the subaudio frequency range i.e. below 30Hz.
~ .
. ~ .
: :
:
, ' .
. .
77~3 According to one aspect of the present invention, there is provided apparatus for monitoring the flow of a stream of particulate solids in a conduit comprising a temperature sensitive electrical resistance device and, in electrical connection with said device, a differentiator for providing a differentiated voltage output proportional to the rate of change of an input voltage from the temperature sensitive electrical resistance device thereby to respond to noise voltages therein and to attenuate lower frequency vari-ations in the input voltage, a rectifier for converting the differentiated voltage output into a direct current output voltage, a filter circuit for attenuating residual components in the direct current output voltage thereby to produce a filtered direct current voltage the magnitude of which is in-dicative of the flow rate of the stream, and a comparator connected to the filter circuit for comparing the direct current voltage with a reference voltage to derive an error signal indicative of the deviation of the actual flow rate from a predetermined flow rate.
According to another aspect of the present invention, there is provided a method for monitoring the flow of a stream of particulate solids in a conduit comprising causing the stream to be in thermal contact with a temperature sensitive electrical resistance device connected to a d.c. volt-age source thereby to generate a voltage signal, differentiating the voltagesignal to give a differentiated voltage output proportional to the rate of change of the voltage signal thereby to respond to noise components in the voltage signal and to attenuate lower frequency components, rectifying and filtering the differentiated voltage output thereby to produce a filtered direct current voltage the magnitude of which is indicative of the flow rate of the stream and comparing the direct current voltage with a reference voltage to derive an error signal indicative of the deviation of the actual . ~ . . .
, .' ': ' ' ., ' ' ' ',. .
.
~L~7773~
.
flo~ rate from a predetermined flow rate.
A suitable temperature sensitive electrical resistance device for use in the operation of this invention is a thermistor. The electrical out-put from the temperature sensitive electrical resistance device may be passed through one or more diferentiation amplification, rectification and filtra-tion stages. More particularly the current from the resistance device may be amplified by amplifying stages, working over the "noise voltage" frequency range and capable of rejecting relatively lower `' ., :` ~
-4a-. ' ' '' :.:, ' ' . . . . .
. ~ . ~ . . .
~; '' ' . OP71 ``' ' ' .
~37773~3 frequencies due to alterations in the operating conditions affecting the performance of the resistance device. The amplified "noise voltages" may be rectified and filtered to provide a direct current voltage which may be used to operate alarm, control or indicating circuits.
The present invention makes the use of equipment designed to identify, and compensate for, interfering variations in operating conditions, such as variations in the mass temperature of a particulate solid, unnecessary and provides a remarkably simple monitoring means.
The invention is particularly suitable for use as a warning of stoppages in the flow of particulate solids. When the flow stops the "noise vol~agesl~ cease and the current derived there-from drops to zero~ The signalling means may be arranged to respond, either instantaneously or after a specified delay period, so as to ignore brief interruptions, either when the current passes a specified minimum value or completely ceases.
It is a further advantage of the invention that an interruption of the electric supply to the resistance device also causes a response from the signalling means, the whole system thus being "fail safe".
According to a modification of the invention the frequency and amplitude of the "noise voltages" may be monitored to give a measure of the flow rate either additionally to, or instead of, flow interruptions.
:
:
~777313 .
The particular equipment utilised in the practice of this invention including the type of therrnistor, if used, and its housing, and the frequency pass-band of the amplifying circuits, may be selected and adjusted to give the best results bearing in mind the identity of the particulate solid and range of its flow rate which it is desired to monitor.
: The method of apparatus of this invention may be used 1to monitor the flow of flowable particulate solids comprising a mixture of particulate materials. The presence of a liquid is not excluded provided that the solid/ particles are distributed throughout the liquid as in a slurry. Examples of suitable flowable particulate solids are powdered coal, sugar, sand, metal powders, inorganic oxides such as titanium dioxide and ground ores such as ground ilmenite ore. Suitably the particulate solid has a largest particle diameter of not more than ~ inch and will not pass a 200 mesh British Standard Sieve. Suitably the conduit has a diameter of,for ex~mple, from 2 to 6 inches.
`An example of a flow monitoring system according to the invention will now be described with reference to the accompanying drawing which is a circuit diagram of the system.
The system comprises a glass encapsulated thermistor 1 arranged, in use, for thermal contact with a flow of particulate solids, connected to a direct current electrical supply, preferably of from 5 to 25 volts, through a resistor 2 preferably having a value of from 250 to 500 ohms. The signal output from the thermistor, comprising "noise voltages"
and relatively lower frequency voltage variations due to changes in operating conditions, is connected through circuitry com-prising a differentiator 5 including a resistor 3 and capacitor ~, an alternating current amplifier 6, a rectifier 7, a filter 8 and a comparator 9. The differentiator 5 comprises an operational amplifier 10 and its associated input and feed back circuit components and gives an output voltage which is proportional to the rate of change of the input voltage.
lQ Low frequency voltage variations in the signal are therefore automatically attenuated. The alternating current ampllfier 6 comprises an operational amplifier 11 with its associated input and feed back circuitry and provides a voltage gain, preferably of from 5 to 15, at the frequencies of interest, that is the "noise voltage" frequencies which are generally helow 30Hz and may very suitably ~e in the range of 1 to lOHz.
The differentiated and amplified "noise voltages" are then passed to a rectifier 7 which gives a direct current output which is passed through a filter circuit 8 comprising capacitors 12 and 13 and resistor 1~ and the residual components are thereby attenuated. The resulting relatively pure direct current voltage is passed to a comparator 9 which comprises an operational amplifier 15 and associated circuitry and which compares it with a reference direct current voltage prefer-ahly of from 0.1 to 0.5 volts. If the voltage applied to the comparator exceeds the reference voltage the comparator output is negative and if the voltage applied to the com-parator falls below the reference voltage the comparator :, . -, .
`
~ ~ OP71 ~i7773~
` .
output is positive. The comparator output is connected to signalling means 16 operated by a change from negative to positive in the input current.
A modification of the equipment described above may be used to give an indication of flow rate. A similar circuit arrangement as that shown in the attached drawing may be used up to the output of the amplifier 6, although some of the component values may be changed. The voltage at this point depends mainly upon the rate of change of the thermistor "noise voltage", and this in turn is related to the velocity of the moving particles. The voltage at this point may be fed into a full-wave bridge rectifier circuit, and the direct current output, after suitable filtering, may be used to drive a moving coil meter. The deflection of the meter is approximately proportional to the flow rate of the particulate solid.
Example ( The system illustrated in the accompanying drawing was used to monitor a flow of sand having an average particle size of 700 microns and a particle size of from 300 microns to 1500 microns falling through a vertical pipe of 4" dia.
under gravity. The thermistor was mounted on an end of a supporting tube which projected radially through the wall .. , of the pipe and supported the thermistor at the axis of the pipe. With reference to the description and drawing of the apparatus use~ the direct current input to the thermistor was 15 volts and the resistor 2 had a value of 390 ohms.
..
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.~ .
The amplifier was selected to give a voltage gain of about 9.5 in the frequency band of l Hz to 10 Hz, which was the "noise voltage" frequency band for flow rates of up to 300 lbs/hr of sand. The amplitude of these voltages was from about 20 to 200m~. The reference voltage used ! in the comparator stage was 0.3 volts.
The pipe was provided with a valve to enable the flow rate to be varied artificially from zero to 300 lbs/hr.
When the rate was allowed to fall to below 15 lbs/hr, and only then, the signalling means was activated.
' . . ' ', ' ,:
~ , .
.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for monitoring the flow of a stream of particulate solids in a conduit comprising a temperature sensitive electrical resistance device and, in electrical connection with said device, a differentiator for provid-ing a differentiated voltage output proportional to the rate of change of an input voltage from the temperature sensitive electrical resistance device thereby to respond to noise voltages therein and to attenuate lower frequency variations in the input voltage, a rectifier for converting the differentiated voltage output into a direct current output voltage, a filter circuit for attenuating residual components in the direct current output voltage thereby to produce a filtered direct current voltage the magnitude of which is in-dicative of the flow rate of the stream, and a comparator connected to the filter circuit for comparing the direct current voltage with a reference voltage to derive an error signal indicative of the deviation of the actual flow rate from a predetermined flow rate.
2. Apparatus as claimed in claim 1, including alarm signalling means connected to the comparator and responsive to an error signal of a predeter-mined minimum value.
3. Apparatus as claimed in claim 1 or claim 2 including a moving coil voltmeter connected to the filter circuit and responsive to the filtered direct current voltage to provide an approximate reading of the flow rate.
4. Apparatus as claimed in claim 1 or 2, including control circuitry connected to the comparator and responsive to the error signal to control the flow rate in a sense to reduce the error signal.
5. Apparatus as claimed in claim 1 or 2 wherein the temperature sensitive electrical resistance device is a thermistor.
6. Apparatus as claimed in claim 1 or 2, including an amplification stage capable of providing a voltage gain in the frequency range of 1 to 10 Hz.
7. Apparatus as claimed in claim 1 or 2 wherein the reference voltage is from 0.1 to 0.5 volts.
8. A method for monitoring the flow of a stream of particulate solids in a conduit comprising causing the stream to be in thermal contact with a temperature sensitive electrical resistance device connected to a d.c. voltage source thereby to generate a voltage signal, differentiating the voltage signal to give a differentiated voltage output proportional to the rate of change of the voltage signal thereby to respond to noise components in the voltage signal and to attenuate lower frequency components, rectifying and filtering the differentiated voltage output thereby to produce a filtered direct current voltage the magnitude of which is indicative of the flow rate of the stream and comparing the direct current voltage with a reference voltage to derive an error signal indicative of the deviation of the actual flow rate from a predetermined flow rate.
9. A method as claimed in claim 8 wherein the voltage source is in the range 5 to 25 volts.
10. A method as claimed in claim 9 wherein the temperature sensitive electrical resistance device is connected in series with a resistor across the voltage source, the resistor having a value in the range 250 to 500 ohms.
11. A method as claimed in any one of claims 8 to 10 wherein the conduit is a pipe having an internal diameter of from 2 to 6 inches.
12. A method as claimed in any one of claims 8 to 10 wherein the particulate solid consists of material having a largest particle diameter of not more than 1/4 inch and which will not pass a 200 mesh British Standard Sieve.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB5251175A GB1564100A (en) | 1975-12-23 | 1975-12-23 | Flow monitoring method and apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1077738A true CA1077738A (en) | 1980-05-20 |
Family
ID=10464198
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA267,462A Expired CA1077738A (en) | 1975-12-23 | 1976-12-08 | Monitoring particulate solid flow in a conduit using a temperature sensitive electrical resistance device |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1077738A (en) |
| GB (1) | GB1564100A (en) |
-
1975
- 1975-12-23 GB GB5251175A patent/GB1564100A/en not_active Expired
-
1976
- 1976-12-08 CA CA267,462A patent/CA1077738A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1564100A (en) | 1980-04-02 |
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| MKEX | Expiry |