CA1085020A - Roller mill performance monitoring by density sensing - Google Patents
Roller mill performance monitoring by density sensingInfo
- Publication number
- CA1085020A CA1085020A CA261,129A CA261129A CA1085020A CA 1085020 A CA1085020 A CA 1085020A CA 261129 A CA261129 A CA 261129A CA 1085020 A CA1085020 A CA 1085020A
- Authority
- CA
- Canada
- Prior art keywords
- mill
- density
- gas
- signal
- gas flow
- 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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C25/00—Control arrangements specially adapted for crushing or disintegrating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
- B02C15/04—Mills with pressed pendularly-mounted rollers, e.g. spring pressed
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
- B02C2015/002—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs combined with a classifier
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- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Crushing And Grinding (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Roller mill operational performance monitored by sensing the density of material in a gas stream passing through the mill and producing a D.C. current proportional to the density of the sensed material and transmitting the proportional D.C. current to a read out.
Roller mill operational performance monitored by sensing the density of material in a gas stream passing through the mill and producing a D.C. current proportional to the density of the sensed material and transmitting the proportional D.C. current to a read out.
Description
~08SOZ0 BACKGROUND OF THE INVENTION
Feed control of roller mills is presently accomplished by controlling the feed of the material to be ground through the measurement of the differential pressure across the mill, that is, from the gas flow inlet ports of the mill to the dis-charge side of the mill. The pressure drop is taken as an indication of the amount of material in the mill. Thus, a high pressure drop is taken to indicate that there is more material in the mill than is desired. Conversely, a low pressure drop is taken to indicate that there is less material in the mill than desired. However, this pressure differential is influenced by three variables, the amount of material in the mill, the gas flow rate through the mill, and the temper-ature of the gas stream. This then is a means of controlling the roller mill as long as the temperature remains constant both at the gas inlet and the outlet side of the mill and providing also that the flow rate of the gas is constant.
However, there are several problems involved with this control method. One is that the pressure drop is dependent upon the
Feed control of roller mills is presently accomplished by controlling the feed of the material to be ground through the measurement of the differential pressure across the mill, that is, from the gas flow inlet ports of the mill to the dis-charge side of the mill. The pressure drop is taken as an indication of the amount of material in the mill. Thus, a high pressure drop is taken to indicate that there is more material in the mill than is desired. Conversely, a low pressure drop is taken to indicate that there is less material in the mill than desired. However, this pressure differential is influenced by three variables, the amount of material in the mill, the gas flow rate through the mill, and the temper-ature of the gas stream. This then is a means of controlling the roller mill as long as the temperature remains constant both at the gas inlet and the outlet side of the mill and providing also that the flow rate of the gas is constant.
However, there are several problems involved with this control method. One is that the pressure drop is dependent upon the
2~ mill differential pressure taps remaining unplugged which, as is well known, is not the case as the taps tend to plug quite frequently. Also the flow rate of the gas is dependent upon similar pressure taps for an indication of a given amount of gas flow. When the pressure taps controlling the gas flow rate become plugged, the gas flow rate can change, while the gas rate flow indicated from the plugged taps remains the same. Such false gas flow indication will not be sensed by the operator or by the control for the gas flow rate system.
Fluctuation in the gas flow rate due to false flow indication will cause a corresponding change in the mill differential pressure, upon which the mill material feed rate is dependent.
-- 1 -- ~
' ~0850Z0 . .
Similarly if the mill pressùre differential taps become plugged a false reading will be received by the feed contxol system.
Also any change in the temperature at the inlet ports to the mill or the mill discharge will cause a change in the mill differential pressure. While the mill discharge temperature is fairly stable, the inlet temperature is subject to variation due to the heat and air flow requirement of the roller mill and the amount of hot gases available from the heat source. As a result of one or more of these conditions, an incorrect a~ount of feed material will be supplied to the mill which could result in damage to the mill. Thus, the problem is not in the basic theory but in its dependenc~ upon other variables and data collection as present methods are not sufficiently dependable.
In U.S. patent 3,459,378 a control arrangement is disclosed wherein a first potentiometer establishes a minimum speed of a conveyor whereby material is fed at a lower rate which rate is acceptable for continuous operation of a crusher and a second potentiometer similarly establishes a maximum conveyor speed whereby material is fed at a higher rate which rate is unacceptable for continuous operation but acceptable for short operational periods. A sensor determines when the unacceptable state is reached and causes a relay to be energized which switches the control from the second potentiometer to the first potentiometer which causes the feed rate to be gradually decreased or lowered, this being in the direction of the acceptable or continuous state of operation. However, a timer periodically deenergizes the relay with the consequence that the control is returned to the second potentiometer irrespectiVe of whether the 3Q unacceptable condition has been eliminated. ~hen the un-acceptable condition or state returns or if it has not been -- ~085020 eliminated, the sensor causes the relay to be immediately energized again and it will remain energized until the timer again deenergizes it, such action resulting in an average material feed rate that is between the acceptable and un-acceptable operational states.
In U.S. patent 3,734,659 a differential pressure or constant flow signal transducer is connected across the lines which extend between a motor and a pump. The signal trans-ducer will, therefore, measure any changes in pressure in these hydraulic feed lines. The variations in pressure produce a signal which is directed to controller which, in turn, controls the operation of the motor whereby the stroke of the pump can be varied. The pressure of the fluid in the lines extending ~etween the motor and the pump change when the screw driven by the motor is subjected to changing conditions. For example, if the material being fed between the compacting rolls increases in density, then the pressure exerted by the rolls on the material will increase. The system will tend to automatically seek relief by a displacement of one or both 2Q of the compacting rolls.
The system disclosed avoids any significant dis-placement, however, by utilizing the signal developed in a transducer. The signal will result in a reduction in the drive pressure applied by the motor to the screw. This reduction in drive pressure will compensate for the tendency toward pressure increase between the compacting rolls whereby the spacing between the rolls can remain constant.
However, while each of the patents discloses the utilization of transducers for purpose of control neither of them teach transducer utilization for measuring density of material in an air stream.
Fluctuation in the gas flow rate due to false flow indication will cause a corresponding change in the mill differential pressure, upon which the mill material feed rate is dependent.
-- 1 -- ~
' ~0850Z0 . .
Similarly if the mill pressùre differential taps become plugged a false reading will be received by the feed contxol system.
Also any change in the temperature at the inlet ports to the mill or the mill discharge will cause a change in the mill differential pressure. While the mill discharge temperature is fairly stable, the inlet temperature is subject to variation due to the heat and air flow requirement of the roller mill and the amount of hot gases available from the heat source. As a result of one or more of these conditions, an incorrect a~ount of feed material will be supplied to the mill which could result in damage to the mill. Thus, the problem is not in the basic theory but in its dependenc~ upon other variables and data collection as present methods are not sufficiently dependable.
In U.S. patent 3,459,378 a control arrangement is disclosed wherein a first potentiometer establishes a minimum speed of a conveyor whereby material is fed at a lower rate which rate is acceptable for continuous operation of a crusher and a second potentiometer similarly establishes a maximum conveyor speed whereby material is fed at a higher rate which rate is unacceptable for continuous operation but acceptable for short operational periods. A sensor determines when the unacceptable state is reached and causes a relay to be energized which switches the control from the second potentiometer to the first potentiometer which causes the feed rate to be gradually decreased or lowered, this being in the direction of the acceptable or continuous state of operation. However, a timer periodically deenergizes the relay with the consequence that the control is returned to the second potentiometer irrespectiVe of whether the 3Q unacceptable condition has been eliminated. ~hen the un-acceptable condition or state returns or if it has not been -- ~085020 eliminated, the sensor causes the relay to be immediately energized again and it will remain energized until the timer again deenergizes it, such action resulting in an average material feed rate that is between the acceptable and un-acceptable operational states.
In U.S. patent 3,734,659 a differential pressure or constant flow signal transducer is connected across the lines which extend between a motor and a pump. The signal trans-ducer will, therefore, measure any changes in pressure in these hydraulic feed lines. The variations in pressure produce a signal which is directed to controller which, in turn, controls the operation of the motor whereby the stroke of the pump can be varied. The pressure of the fluid in the lines extending ~etween the motor and the pump change when the screw driven by the motor is subjected to changing conditions. For example, if the material being fed between the compacting rolls increases in density, then the pressure exerted by the rolls on the material will increase. The system will tend to automatically seek relief by a displacement of one or both 2Q of the compacting rolls.
The system disclosed avoids any significant dis-placement, however, by utilizing the signal developed in a transducer. The signal will result in a reduction in the drive pressure applied by the motor to the screw. This reduction in drive pressure will compensate for the tendency toward pressure increase between the compacting rolls whereby the spacing between the rolls can remain constant.
However, while each of the patents discloses the utilization of transducers for purpose of control neither of them teach transducer utilization for measuring density of material in an air stream.
3 --SUMMARY OF TIIE INVENTION
It is a general object of this invention to provide a means for providing prior reliable data for monitoring the operational performance of a roller mill.
In accordance with the present invention the potential voltage between a transducer or electrode probe inserted through the wall of the roller mill and the wall of the mill is measured. Thus, the density of material around the transducer or probe will increase the potential voltage which can be utilized to produce a D.C. current proportional to the density sensed and the signal can be fed to a read out to provide usable data information. The location of the transducer is within the mill in the path of the gas flow stream which has suspended in it processed material. Thus, as the density of the material suspended in the air flow increases the potential voltage also increases. Therefore, a variation from an established potential voltage norm, either above or below, will indicate that a correction in the rate of material fed into the mill must be accomplished. A potential voltage above the established norm will indicate that the rate of material fed is too great. Conversely, a potential voltage below the - established norm will indicate the rate of material being fed into the mill should be increased.
This method of control is not dependent nor is it affected by the temperature or the gas flow. Since there are no taps there is nothing to plug. In addition the transducer or probe sensing and indication is immediate without lag.
In accordance with a specific embodiment, the method of monitoring the operational performance of a roller mill having an air flow inlet and an outlet; comprises the steps of:
sensing the density of materials in the air flow stream, moving through the mill between the inlet and outlet,
It is a general object of this invention to provide a means for providing prior reliable data for monitoring the operational performance of a roller mill.
In accordance with the present invention the potential voltage between a transducer or electrode probe inserted through the wall of the roller mill and the wall of the mill is measured. Thus, the density of material around the transducer or probe will increase the potential voltage which can be utilized to produce a D.C. current proportional to the density sensed and the signal can be fed to a read out to provide usable data information. The location of the transducer is within the mill in the path of the gas flow stream which has suspended in it processed material. Thus, as the density of the material suspended in the air flow increases the potential voltage also increases. Therefore, a variation from an established potential voltage norm, either above or below, will indicate that a correction in the rate of material fed into the mill must be accomplished. A potential voltage above the established norm will indicate that the rate of material fed is too great. Conversely, a potential voltage below the - established norm will indicate the rate of material being fed into the mill should be increased.
This method of control is not dependent nor is it affected by the temperature or the gas flow. Since there are no taps there is nothing to plug. In addition the transducer or probe sensing and indication is immediate without lag.
In accordance with a specific embodiment, the method of monitoring the operational performance of a roller mill having an air flow inlet and an outlet; comprises the steps of:
sensing the density of materials in the air flow stream, moving through the mill between the inlet and outlet,
4 -producing an electrical analog signal indicative of said sensed density, and providing an indication of said electrical signal.
In a further embodiment, the method of monitoring the operational performance of a roller mill having an air flow inlet and an outlet, comprising the steps of:
! sensing the density of materials in the air flow stream moving through the mill between the inlet and outlet, measuring the potential voltage between the sensor and the wall of the mill, and, indicating the measured potential voltage on a meter.
In accordance with a still further embodiment, the method of monitoring the operational performance of a roller mill having material feeding means and an air flow inlet and outlet for directing air through the mill, comprising the steps of:
; establishin~ a desired potential voltage level for material to be processed in the mill, sensing the density of the material in the air flow stream passing through the mill;
measuring the potential voltage between the sensor and the wall of the mill, and, indicating the measured potential voltage in usable form.
In a still further embodiment, the method of controlling the operational performance of a roller mill having a material input feed, and provided with a gas flow inlet and outlet for passing a stream of gas through the mill, comprising the steps of:
establishing a potential voltage for material which is being processed in the mill when the mill is operating at ~ - 4a -~()8SOZO
a deslred level of efficiency, sensing the density of the material in the gas flow stream passing through the mill, measuring the potential voltage of the material the density of which has been sensed between the sensing point and the wall of the mill:
translating the measured potential voltage into usable data; and, controlling the material input feed to the mill in accordance with the data obtained.
In a still further embodiment, the method of monitoring the operational performance of a roller mill having material feeding means and a gas flow inlet and outlet for directing a flow of gas through the mill, comprising the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill;
B) sensing the density of materials in the gas flow stream passing through the mill and producing a signal;
and, C) supplying the signal to a signal conditioner to produce current which is proportional to the density of the material sensed.
In a still further embodiment, the method of monitoring the operational performance of a roller mill having a gas flow stream passing through the mill, comprising the steps of:
A) inserting a transducer into the gas stream to : sense the density of material in the gas flow stream passing through the mill to produce a signal;
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B) applying the signal produ-ed to a signal conditioner to produce a D.C. current proportional to the density of the material that has been sensed, and, C) applying the D.C. current to a read out.
From a different aspect,the invention relates to, in a roller mill having a grinding plate and a plurality of grinding rollers operably arranged to grind material, the roller mill being provided with a power driven material supply means operable to feed material to be ground to the grinding plate, said roller mill also having a gas inlet and a gas outlet for providing a gas flow passage through the mill, means for supplying gas at a predetermined rate to the inlet of the mill for passage through the mill, a sensing means extending within the interior of the mill into the gas stream moving through the mill, said sensing means being responsive to the density of materials in said gas stream to produce a signal, and, means external of the mill and operably connected to said sensing means to receive a signal from said sensing means to produce an analog signal proportional to the density of the material sensed by said sensing means.
DESCRIPTION OF THE DR7~WING
Fig. 1 is a view in vertical section through a roller mill with a schematic showing of the material feed - 4c -10850Z() to the mill, the probe control ~eing shown in operatiVe position and connected to a meter on a control panel.
DESCRIPTION OF THE INVENTION
The roller mill 10 includes grinding rollers 11 which run on a grinding plate 12 which rotates about a vertical axis. A motor 14 is operably connected through appropriate gearing to drive the grinding plate 12 in a well known manner. Circumferentially and below the plate 12 is a gas flow distribution ring 16 which is connected to a gas flow inlet pipe 17. The inlet pipe may be connected if desired to an exhaust gas pipe of the system with which the roller grinder 10 is associated, or the inlet may be connected to a source of ambient air. The distribution gas flow ring 16 is provided with a plurality of spaced apart ports 18 which direct the gas flow as indicated by directional arrows 19 at a relatively high volume which is sufficient to elevate the material processed on the plate 12. The stream of gas moves upwardly carrying the ground material along with it. A hood or cap 21 serves to close the top of the mill and also serves as a support for a power driven classifier fan 22.
The dust or fine laden gas stream passes through the classifier fan Z2 which operates to return the coarse particles carried in the gas stream to the grinding plate for regrinding. The gas stream carrying the relatively finely ground material exits from the roller mill via a gas flow outlet 26. The outlet 26 is connected to a cyclone 27 which communicates with a fan 28 that directs the gases containing material not extracted by the cyclone to a separator such as a bag house or an electrostatic precipitator (not shown) in a well known manner. A portion of these gases are recycled through the mill to compensate the availa~le gas flow.
In a further embodiment, the method of monitoring the operational performance of a roller mill having an air flow inlet and an outlet, comprising the steps of:
! sensing the density of materials in the air flow stream moving through the mill between the inlet and outlet, measuring the potential voltage between the sensor and the wall of the mill, and, indicating the measured potential voltage on a meter.
In accordance with a still further embodiment, the method of monitoring the operational performance of a roller mill having material feeding means and an air flow inlet and outlet for directing air through the mill, comprising the steps of:
; establishin~ a desired potential voltage level for material to be processed in the mill, sensing the density of the material in the air flow stream passing through the mill;
measuring the potential voltage between the sensor and the wall of the mill, and, indicating the measured potential voltage in usable form.
In a still further embodiment, the method of controlling the operational performance of a roller mill having a material input feed, and provided with a gas flow inlet and outlet for passing a stream of gas through the mill, comprising the steps of:
establishing a potential voltage for material which is being processed in the mill when the mill is operating at ~ - 4a -~()8SOZO
a deslred level of efficiency, sensing the density of the material in the gas flow stream passing through the mill, measuring the potential voltage of the material the density of which has been sensed between the sensing point and the wall of the mill:
translating the measured potential voltage into usable data; and, controlling the material input feed to the mill in accordance with the data obtained.
In a still further embodiment, the method of monitoring the operational performance of a roller mill having material feeding means and a gas flow inlet and outlet for directing a flow of gas through the mill, comprising the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill;
B) sensing the density of materials in the gas flow stream passing through the mill and producing a signal;
and, C) supplying the signal to a signal conditioner to produce current which is proportional to the density of the material sensed.
In a still further embodiment, the method of monitoring the operational performance of a roller mill having a gas flow stream passing through the mill, comprising the steps of:
A) inserting a transducer into the gas stream to : sense the density of material in the gas flow stream passing through the mill to produce a signal;
- 4b -.
B) applying the signal produ-ed to a signal conditioner to produce a D.C. current proportional to the density of the material that has been sensed, and, C) applying the D.C. current to a read out.
From a different aspect,the invention relates to, in a roller mill having a grinding plate and a plurality of grinding rollers operably arranged to grind material, the roller mill being provided with a power driven material supply means operable to feed material to be ground to the grinding plate, said roller mill also having a gas inlet and a gas outlet for providing a gas flow passage through the mill, means for supplying gas at a predetermined rate to the inlet of the mill for passage through the mill, a sensing means extending within the interior of the mill into the gas stream moving through the mill, said sensing means being responsive to the density of materials in said gas stream to produce a signal, and, means external of the mill and operably connected to said sensing means to receive a signal from said sensing means to produce an analog signal proportional to the density of the material sensed by said sensing means.
DESCRIPTION OF THE DR7~WING
Fig. 1 is a view in vertical section through a roller mill with a schematic showing of the material feed - 4c -10850Z() to the mill, the probe control ~eing shown in operatiVe position and connected to a meter on a control panel.
DESCRIPTION OF THE INVENTION
The roller mill 10 includes grinding rollers 11 which run on a grinding plate 12 which rotates about a vertical axis. A motor 14 is operably connected through appropriate gearing to drive the grinding plate 12 in a well known manner. Circumferentially and below the plate 12 is a gas flow distribution ring 16 which is connected to a gas flow inlet pipe 17. The inlet pipe may be connected if desired to an exhaust gas pipe of the system with which the roller grinder 10 is associated, or the inlet may be connected to a source of ambient air. The distribution gas flow ring 16 is provided with a plurality of spaced apart ports 18 which direct the gas flow as indicated by directional arrows 19 at a relatively high volume which is sufficient to elevate the material processed on the plate 12. The stream of gas moves upwardly carrying the ground material along with it. A hood or cap 21 serves to close the top of the mill and also serves as a support for a power driven classifier fan 22.
The dust or fine laden gas stream passes through the classifier fan Z2 which operates to return the coarse particles carried in the gas stream to the grinding plate for regrinding. The gas stream carrying the relatively finely ground material exits from the roller mill via a gas flow outlet 26. The outlet 26 is connected to a cyclone 27 which communicates with a fan 28 that directs the gases containing material not extracted by the cyclone to a separator such as a bag house or an electrostatic precipitator (not shown) in a well known manner. A portion of these gases are recycled through the mill to compensate the availa~le gas flow.
- 5 --" ~08SOZ0 Material 'to be ground is delivered to the roller mill 10 from a bin 31 via an associated chute 32. The bin 31 is supplied from a materials belt conveyor 33 power driven by a motor 34. Thus, by increasing or decreasing the speed of the conveyor motor 34 the speed of the belt conveyor can be regulated to increase or decrease the supply of the materials fed to the mill 10.
Grinding capacity of the mill can be increased by increasing the gas flow through the mill. To this purpose, 10 a damper 37 is opened and power to a motor 38 which drives the fan 28 is increased. Power to the fan motor 38 is ~ndicated on a connected meter 39 which indicates in kilowatts the power delivered to the motor. Power to the grinding plate motor 14 is also indicated on a meter 41 similar to the meter 39.
Known methods of controlling the mill 10 is by view-ing a manometer 46, a basic illustration of the instrument being made. It will be appreciated that a commercially avail-able manometer would be utilized. As shown, the manometer 46 20 has one end connected via pressure tap 47 into the gas flow distribution ring 16 and its opposite end connected via pressure tap 48 into the mill at the discharge side of the mill. Thus, the manometer 46 indicates in inches of water the differential pressure across the mill. This pressure drop has been taken as an indication of the amount of material in the mill.
Thus, with material supplied to the grinding plate 12 to maintain a material thickness on the plate at a desired thickness, for example, three inches, the pressure drop readings at that leveI of thickness is established as the 3~ desire~l norm. Thus, a pressure drop indicated on the manometer 46 which is higher than the established norm would indicate that the feeder belt 33 should be operated at a slower speed to decrease the amount of material supplied to the grinding plate 12. Conversely, a pressure drop on the manometer which is below the established norm would be an indication that the grinding plate is not sufficiently supplied with material. Too little material to the mill can result in severe vibrations being experienced which could cause damage both to the grinding wheels and/or the grinding plate. Too much material will result in choking of the mill.
The accuracy of the pressure drop indication on the manometer 46 is dependent upon the conditions of a constant flow rate of gas from the distribution ring 16 and steady temperatures at the pressure taps 47 and 48, as well as being dependent upon the pressure taps 47 and 48 remaining unclogged. However, a constant flow rate of gas is dependent upon the pressure taps of the cyclone manometer 57 remaining unclogged. Plugging of the pressure taps of the cyclone manometer 57 frequently occurs and more particularly when water sprays are utilized to moisturize the material. When the pressure taps of cyclone 2Q manometer 57 become plugged, the indication of gas flow rate would not indicate a correct gas flow. A higher gas flow may really exist and as a result of the higher gas flow a higher pressure drop would be indicated on the mill differential pressure manometer 46 due to the gas flow. The operator ; controlling the mill could not know of this condition and would lower the feed rate of the conveyor 33 to maintain the pressure drop at the established norm. This of course would result in the mill being starved and too little material would ~e deIivered resulting in damage to the internal portions 3Q of the mill.
To avoid dependency of mill control on the pressure drop readings the monitoring of the density of the material in the gas flow~,stream was conceived as a more reIiable means of controlling the mill. To this end a potential measuring means 51 such as a transducer 52 is provided. As shown, the tranducer 52 extends through the wall of the mill 10 into the gas flow stream from the ports 18. The transducer 52 measures potential voltage from the tranducer or probe 52 to the wall of the mill. As the gas flow stream moves through the mill from the inlet 17 and out through the outlet 26 it picks up the finely ground material. As the material in the gas flow stream moves past the transducer 52 the potential voltage from the probe to the wall of the mill will be increased and measured by the transducer 52. Thus, by noting the potential voltage as measured by the trans-ducer 52 when the mill is operating at a desired level a potential voltage norm can be established. Any deviation from the potential voltage norm either above or below the established norm will indicate a greater material density or lesser density. A greater density indication will indicate ; that the conveyor feed rate should be slowed to feed less material to the mill. Conversely, a density below the norm will indicate that the mill requires more material and therefore the conveyor feed rate should be increased. The potential voltage sensed by the tranducer 52 is transmitted to a signal conditioner 53 to produce a D.C. current which is proportional to the density of the sensed material.
The sensing of the density of the material passing the transducer 52 provides a more reliable control method because ~ .
it is not dependent upon the temperature or the air flow and cannot become plugged. The simplicity of the arrangement insures 3Q positive indication of the mill condition, thereby insuring maximum efficiency. The proportional D.C. current is trans-., .
mitted to a read out 56 which provides the operator with usefuldat:a for effecting necessar~ correction in the feed rate of the conveyor 33.
It will be understood that the proportional D.C.
current from the signal conditioner 53 could be amplified and transmitted to a motor controller (not shown) which would be connected to control the conveyor motor 34 if so desired, to provide for an automated system.
_ g _ 108~0;~0 SUPPLEMENTARY DISCLOSURE
The foregoing has spoken in general terms of a signal conditioner. Signal conditioners are well known in the art, and any of the well known signal conditioners can be used to practice the present invention. A specific implementation of such a signal conditioner is described in the following.
With the signal conditioner as described in the following, the invention is carried out by producing a current proportional to the density of the materials in the mills, rectifying the current, and providing the rectified current to an output meter.
Specifically, in accordance with the invention, and utilizing the described signal conditioner, the method of monitoring the operational performance of a roller mill having a rnaterial feeding means and a gas flow inlet and outlet for directing the flow of gas through the mill, comprises the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill, B) sensing the density of materials in the gas flow stream passing through the mill and producing a signal, C) supplying the signal to a signal conditioner to produce current which is proportional to the density of the material sensed, and D) applying the produced current which is proportional to the density of the material sensed to a read out.
In a further embodiment the method of monitoring the operational performance of a roller mill having a gas flow stream passing through the mill, comprising the steps of:
...
.
~0~5020 A) inserting a transducer into the gas stream to sense the density of material in the gas flow stream passing through the mill to produce a signal;
B) applying the signal produced to a signal conditioner to produce a D.C. current proportional to the density of the material that has been sensed; and, ! C) applying the D.C. current to read out.
In a still further embodiment the method of monitoring the operational performance of a roller mill having an air flow inlet and an airflow outlet; comprising the steps of, exhibiting the capacitance between a sensor and its quiescent surrounding within the mill; and, indicating the exhibited capacitance on a meter wherein such indication is proportional to the density of material in the air flow stream.
In a still further embodiment, the method of monitoring the operational performance of a roller mill having material feeding means and a gas flow inlet and outlet for directing a flow of gas through the mill; comprising the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill;
B) sensing the density of the materials in the gas flow stream passing through the mill as the mill is operating;
C) producing a signal which reflects the density of the material in the air flow stream which is being sensed, D) supplying the signal to a signal conditioner to produce current which is proportional to the density of material sensed;
.
E) applying the produced current to a meter to activate the meter, and, F) utilizing the indicated data from the meter to control the operation of the mill.
From a different aspect, the invention relates to, in a roller mill having a grinding plate and a plurality of grindingrollers operably arranged to grind material, the roller mill being provided with a power driven material supply means operable to feed material to be ground to the grinding plate, said roller mill also having a gas inlet and a gas outlet for providing a gas flow passage through the mill;
means for supplying gas at a predetermined rate to the inlet of the mill for passage through the mill;
a sensing means extending within the interior of the mill into the gas stream moving through the mill, said sensing means being responsive to the density of materials in said gas stream to produce a signal; and, a means external of the mill and operably connected to said sensing means to receive a signal from said sensing means to produce an analog signal proportional to the density of the material sensed by said sensing means.
The signal conditioner will be described below together with the accompanying drawing in which:
FIGURE 2 is a schematic representation of a signal conditioner.
Referring to Figure 2, the signal conditioner 53 may be of any well-known arrangement and in genera1includes an oscillator such as the tube 61 which is made to go into oscillation at a predetermined frequencyO For this purpose, a class "C" amplifier comprising a tube 61 is connected to a feedback network comprising capacitor C3, the tapped inductor 62 and the capacitor C2 which is connected to the cathode of the tube 61.
This arrangement provides a voltage that is fed into and comes out of the amplifier in phase with it. The feedback network also provides a magnitude of voltage which is fed into the amplifier that is sufficient such that the gain of the amplifier times the loss through the network is equal to one or greater. This establishes the condition for oscillation. If the signal being fed back is in phase with the output signal and the overall loop gain due to the feedback network is at least that times the gain of the amplifier and is at least unity, the tube 61 then acts as oscillator. These conditions are met with the variable capacitors C2 and C3 and the phase shift is brought about by the inductor 62 acting in cooperation with the variable capacitor and commonly referred to as a tank or resonant circuit. By taking the output ; of the cathode of tube 61 at the top point of the tank circuit, a sample is obtained of the current from the feedback eircuit or loop. By connecting a meter, such as the microammeter 56, out through a diode detector 63, the sample may be indicated as usual data. This is true because the diode 63 clipps off the positive peaks of the sine wave form. Then the average value is ~0 finite. Now taking this somewhat negative average value and putting it through a filter, the voltage is applied across the microammeter 56 to cause a deflection of the indicator thereof which deflection indicates the density of the material in the air flow stream moving past the probe 52. The magnitude of the signal obtained is dependent upon how close or how high the Q is of the tank or resonant circuit and that can be altered by ; ~ adjusting the capacitors C2 and C3, or by setting them and introducing some additional capacitance, as in the present instance. This is accomplished by connecting the ~d of the tube 61 through a 1,000 pf capacitor and the probe 52 coupled thereto, the probe having its capacitance to ground and is small.
The total capacitance, environmental capacitance will equal the ~r`
.~ .
--` 108SOZO
product of C5 plus C probe. If C5 is small and C probe is large, a number is obtained which is less than C probe. The smaller of the two capacitances will dominate. So the capacitance of the probe 52 is variable, due to the environment in the mill in which the probe is located, and alters the feedback network which has been established by C2, C3, the inductor 62 and the operating condition of the amplifier. By introducing a small amount of capacitance the frequency of the oscillator can be controlled.
Because of the Q of the network, which is the feedback level, the amount of oscillation current can be increased by changing the resonant frequency which alters the Q of the circuit. C2, C3 and the inductor 62 form the feedback network required to make the tube amplifier 61 oscillate so that it becomes an oscillator. The introduction of C5 in series with the inherent probe capacitance brings about the inception of oscillation and subsequent change in oscillation if any. The capacitors C2 and C3 are adjusted so that with minimum influence around the probe 52, the oscillations are of a very minimum amplitude or nil, and with the introduction of a slight increase of material density around the probe, the oscillation amplitude is increased. The detector network takes a sample of the voltage, rectifies it and applies it to the meter 56. The value read on the meter is proportional to the peak amplitude. Thus, as the density of the material around the probe increases, the higher the meter reading will be. By noting a meter reading when the mill is operating at optimum, a variation from the noted reading is usable data for controlling the mill, that is, for either increasing or decreasing the feed into the mill.
It will be understood that the proportional D.C.
current from the signal conditioner 53 could be amplified and transmitted to a motor controller (not shown) which would be connected to control the conveyor motor 34 if so desired, to provide for an automated system.
,.~
Grinding capacity of the mill can be increased by increasing the gas flow through the mill. To this purpose, 10 a damper 37 is opened and power to a motor 38 which drives the fan 28 is increased. Power to the fan motor 38 is ~ndicated on a connected meter 39 which indicates in kilowatts the power delivered to the motor. Power to the grinding plate motor 14 is also indicated on a meter 41 similar to the meter 39.
Known methods of controlling the mill 10 is by view-ing a manometer 46, a basic illustration of the instrument being made. It will be appreciated that a commercially avail-able manometer would be utilized. As shown, the manometer 46 20 has one end connected via pressure tap 47 into the gas flow distribution ring 16 and its opposite end connected via pressure tap 48 into the mill at the discharge side of the mill. Thus, the manometer 46 indicates in inches of water the differential pressure across the mill. This pressure drop has been taken as an indication of the amount of material in the mill.
Thus, with material supplied to the grinding plate 12 to maintain a material thickness on the plate at a desired thickness, for example, three inches, the pressure drop readings at that leveI of thickness is established as the 3~ desire~l norm. Thus, a pressure drop indicated on the manometer 46 which is higher than the established norm would indicate that the feeder belt 33 should be operated at a slower speed to decrease the amount of material supplied to the grinding plate 12. Conversely, a pressure drop on the manometer which is below the established norm would be an indication that the grinding plate is not sufficiently supplied with material. Too little material to the mill can result in severe vibrations being experienced which could cause damage both to the grinding wheels and/or the grinding plate. Too much material will result in choking of the mill.
The accuracy of the pressure drop indication on the manometer 46 is dependent upon the conditions of a constant flow rate of gas from the distribution ring 16 and steady temperatures at the pressure taps 47 and 48, as well as being dependent upon the pressure taps 47 and 48 remaining unclogged. However, a constant flow rate of gas is dependent upon the pressure taps of the cyclone manometer 57 remaining unclogged. Plugging of the pressure taps of the cyclone manometer 57 frequently occurs and more particularly when water sprays are utilized to moisturize the material. When the pressure taps of cyclone 2Q manometer 57 become plugged, the indication of gas flow rate would not indicate a correct gas flow. A higher gas flow may really exist and as a result of the higher gas flow a higher pressure drop would be indicated on the mill differential pressure manometer 46 due to the gas flow. The operator ; controlling the mill could not know of this condition and would lower the feed rate of the conveyor 33 to maintain the pressure drop at the established norm. This of course would result in the mill being starved and too little material would ~e deIivered resulting in damage to the internal portions 3Q of the mill.
To avoid dependency of mill control on the pressure drop readings the monitoring of the density of the material in the gas flow~,stream was conceived as a more reIiable means of controlling the mill. To this end a potential measuring means 51 such as a transducer 52 is provided. As shown, the tranducer 52 extends through the wall of the mill 10 into the gas flow stream from the ports 18. The transducer 52 measures potential voltage from the tranducer or probe 52 to the wall of the mill. As the gas flow stream moves through the mill from the inlet 17 and out through the outlet 26 it picks up the finely ground material. As the material in the gas flow stream moves past the transducer 52 the potential voltage from the probe to the wall of the mill will be increased and measured by the transducer 52. Thus, by noting the potential voltage as measured by the trans-ducer 52 when the mill is operating at a desired level a potential voltage norm can be established. Any deviation from the potential voltage norm either above or below the established norm will indicate a greater material density or lesser density. A greater density indication will indicate ; that the conveyor feed rate should be slowed to feed less material to the mill. Conversely, a density below the norm will indicate that the mill requires more material and therefore the conveyor feed rate should be increased. The potential voltage sensed by the tranducer 52 is transmitted to a signal conditioner 53 to produce a D.C. current which is proportional to the density of the sensed material.
The sensing of the density of the material passing the transducer 52 provides a more reliable control method because ~ .
it is not dependent upon the temperature or the air flow and cannot become plugged. The simplicity of the arrangement insures 3Q positive indication of the mill condition, thereby insuring maximum efficiency. The proportional D.C. current is trans-., .
mitted to a read out 56 which provides the operator with usefuldat:a for effecting necessar~ correction in the feed rate of the conveyor 33.
It will be understood that the proportional D.C.
current from the signal conditioner 53 could be amplified and transmitted to a motor controller (not shown) which would be connected to control the conveyor motor 34 if so desired, to provide for an automated system.
_ g _ 108~0;~0 SUPPLEMENTARY DISCLOSURE
The foregoing has spoken in general terms of a signal conditioner. Signal conditioners are well known in the art, and any of the well known signal conditioners can be used to practice the present invention. A specific implementation of such a signal conditioner is described in the following.
With the signal conditioner as described in the following, the invention is carried out by producing a current proportional to the density of the materials in the mills, rectifying the current, and providing the rectified current to an output meter.
Specifically, in accordance with the invention, and utilizing the described signal conditioner, the method of monitoring the operational performance of a roller mill having a rnaterial feeding means and a gas flow inlet and outlet for directing the flow of gas through the mill, comprises the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill, B) sensing the density of materials in the gas flow stream passing through the mill and producing a signal, C) supplying the signal to a signal conditioner to produce current which is proportional to the density of the material sensed, and D) applying the produced current which is proportional to the density of the material sensed to a read out.
In a further embodiment the method of monitoring the operational performance of a roller mill having a gas flow stream passing through the mill, comprising the steps of:
...
.
~0~5020 A) inserting a transducer into the gas stream to sense the density of material in the gas flow stream passing through the mill to produce a signal;
B) applying the signal produced to a signal conditioner to produce a D.C. current proportional to the density of the material that has been sensed; and, ! C) applying the D.C. current to read out.
In a still further embodiment the method of monitoring the operational performance of a roller mill having an air flow inlet and an airflow outlet; comprising the steps of, exhibiting the capacitance between a sensor and its quiescent surrounding within the mill; and, indicating the exhibited capacitance on a meter wherein such indication is proportional to the density of material in the air flow stream.
In a still further embodiment, the method of monitoring the operational performance of a roller mill having material feeding means and a gas flow inlet and outlet for directing a flow of gas through the mill; comprising the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill;
B) sensing the density of the materials in the gas flow stream passing through the mill as the mill is operating;
C) producing a signal which reflects the density of the material in the air flow stream which is being sensed, D) supplying the signal to a signal conditioner to produce current which is proportional to the density of material sensed;
.
E) applying the produced current to a meter to activate the meter, and, F) utilizing the indicated data from the meter to control the operation of the mill.
From a different aspect, the invention relates to, in a roller mill having a grinding plate and a plurality of grindingrollers operably arranged to grind material, the roller mill being provided with a power driven material supply means operable to feed material to be ground to the grinding plate, said roller mill also having a gas inlet and a gas outlet for providing a gas flow passage through the mill;
means for supplying gas at a predetermined rate to the inlet of the mill for passage through the mill;
a sensing means extending within the interior of the mill into the gas stream moving through the mill, said sensing means being responsive to the density of materials in said gas stream to produce a signal; and, a means external of the mill and operably connected to said sensing means to receive a signal from said sensing means to produce an analog signal proportional to the density of the material sensed by said sensing means.
The signal conditioner will be described below together with the accompanying drawing in which:
FIGURE 2 is a schematic representation of a signal conditioner.
Referring to Figure 2, the signal conditioner 53 may be of any well-known arrangement and in genera1includes an oscillator such as the tube 61 which is made to go into oscillation at a predetermined frequencyO For this purpose, a class "C" amplifier comprising a tube 61 is connected to a feedback network comprising capacitor C3, the tapped inductor 62 and the capacitor C2 which is connected to the cathode of the tube 61.
This arrangement provides a voltage that is fed into and comes out of the amplifier in phase with it. The feedback network also provides a magnitude of voltage which is fed into the amplifier that is sufficient such that the gain of the amplifier times the loss through the network is equal to one or greater. This establishes the condition for oscillation. If the signal being fed back is in phase with the output signal and the overall loop gain due to the feedback network is at least that times the gain of the amplifier and is at least unity, the tube 61 then acts as oscillator. These conditions are met with the variable capacitors C2 and C3 and the phase shift is brought about by the inductor 62 acting in cooperation with the variable capacitor and commonly referred to as a tank or resonant circuit. By taking the output ; of the cathode of tube 61 at the top point of the tank circuit, a sample is obtained of the current from the feedback eircuit or loop. By connecting a meter, such as the microammeter 56, out through a diode detector 63, the sample may be indicated as usual data. This is true because the diode 63 clipps off the positive peaks of the sine wave form. Then the average value is ~0 finite. Now taking this somewhat negative average value and putting it through a filter, the voltage is applied across the microammeter 56 to cause a deflection of the indicator thereof which deflection indicates the density of the material in the air flow stream moving past the probe 52. The magnitude of the signal obtained is dependent upon how close or how high the Q is of the tank or resonant circuit and that can be altered by ; ~ adjusting the capacitors C2 and C3, or by setting them and introducing some additional capacitance, as in the present instance. This is accomplished by connecting the ~d of the tube 61 through a 1,000 pf capacitor and the probe 52 coupled thereto, the probe having its capacitance to ground and is small.
The total capacitance, environmental capacitance will equal the ~r`
.~ .
--` 108SOZO
product of C5 plus C probe. If C5 is small and C probe is large, a number is obtained which is less than C probe. The smaller of the two capacitances will dominate. So the capacitance of the probe 52 is variable, due to the environment in the mill in which the probe is located, and alters the feedback network which has been established by C2, C3, the inductor 62 and the operating condition of the amplifier. By introducing a small amount of capacitance the frequency of the oscillator can be controlled.
Because of the Q of the network, which is the feedback level, the amount of oscillation current can be increased by changing the resonant frequency which alters the Q of the circuit. C2, C3 and the inductor 62 form the feedback network required to make the tube amplifier 61 oscillate so that it becomes an oscillator. The introduction of C5 in series with the inherent probe capacitance brings about the inception of oscillation and subsequent change in oscillation if any. The capacitors C2 and C3 are adjusted so that with minimum influence around the probe 52, the oscillations are of a very minimum amplitude or nil, and with the introduction of a slight increase of material density around the probe, the oscillation amplitude is increased. The detector network takes a sample of the voltage, rectifies it and applies it to the meter 56. The value read on the meter is proportional to the peak amplitude. Thus, as the density of the material around the probe increases, the higher the meter reading will be. By noting a meter reading when the mill is operating at optimum, a variation from the noted reading is usable data for controlling the mill, that is, for either increasing or decreasing the feed into the mill.
It will be understood that the proportional D.C.
current from the signal conditioner 53 could be amplified and transmitted to a motor controller (not shown) which would be connected to control the conveyor motor 34 if so desired, to provide for an automated system.
,.~
Claims (13)
1. The method of monitoring the operational performance of a roller mill having an air flow inlet and an outlet; comprising the steps of:
sensing the density of materials in the air flow stream moving through the mill between the inlet and outlet;
measuring the potential voltage between the sensor and the wall of the mill; and, indicating the measured potential voltage on a meter.
sensing the density of materials in the air flow stream moving through the mill between the inlet and outlet;
measuring the potential voltage between the sensor and the wall of the mill; and, indicating the measured potential voltage on a meter.
2. The method of monitoring the operational performance of a roller mill having material feeding means and an air flow inlet and outlet for directing air through the mill; comprising the steps of:
establishing a desired potential voltage level for material to be processed in the mill;
sensing the density of the material in the air flow stream passing through the mill;
measuring the potential voltage between the sensor and the wall of the mill; and, indicating the measured potential voltage in usable form.
establishing a desired potential voltage level for material to be processed in the mill;
sensing the density of the material in the air flow stream passing through the mill;
measuring the potential voltage between the sensor and the wall of the mill; and, indicating the measured potential voltage in usable form.
3. The method of controlling the operational performance of a roller mill having a material input feed, and provided with a gas flow inlet and outlet for passing a stream of gas through the mill; comprising the steps of:
establishing a potential voltage for material which is being processed in the mill when the mill is operating at a desired level of efficiency;
sensing the density of the material in the gas flow stream passing through the mill;
measuring the potential voltage of the material the density of which has been sensed between the sensing point and the wall of the mill;
translating the measured potential voltage into usable data; and, controlling the material input feed to the mill in accordance with the data obtained.
establishing a potential voltage for material which is being processed in the mill when the mill is operating at a desired level of efficiency;
sensing the density of the material in the gas flow stream passing through the mill;
measuring the potential voltage of the material the density of which has been sensed between the sensing point and the wall of the mill;
translating the measured potential voltage into usable data; and, controlling the material input feed to the mill in accordance with the data obtained.
4. The method of monitoring the operational performance of a roller mill having material feeding means and a gas flow inlet and outlet for directing a flow of gas through the mill; comprising the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill;
B) sensing the density of materials in the gas flow stream passing through the mill and producing a signal;
and, C) supplying the signal to a signal conditioner to produce current which is proportional to the density of the material sensed.
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill;
B) sensing the density of materials in the gas flow stream passing through the mill and producing a signal;
and, C) supplying the signal to a signal conditioner to produce current which is proportional to the density of the material sensed.
5. The method of monitoring the operational performance of a roller mill according to claim 4, comprising the additional step of:
applying the produced current which is proportional to the density of the material sensed to a read out.
applying the produced current which is proportional to the density of the material sensed to a read out.
6. The method of monitoring the operational per-formance of a roller mill having a gas flow stream passing through the mill; comprising the steps of:
A) inserting a transducer into the gas stream to sense the density of material in the gas flow stream passing through the mill to produce a signal;
B) applying the signal produced to a signal conditioner to produce a D.C. current proportional to the density of the material that has been sensed; and, C) applying the D.C. current to a read out.
A) inserting a transducer into the gas stream to sense the density of material in the gas flow stream passing through the mill to produce a signal;
B) applying the signal produced to a signal conditioner to produce a D.C. current proportional to the density of the material that has been sensed; and, C) applying the D.C. current to a read out.
7. In a roller mill having a grinding plate and a plurality of grinding rollers operably arranged to grind material, the roller mill being provided with a power driven material supply means operable to feed material to be ground to the grinding plate, said roller mill also having a gas inlet and a gas outlet for providing a gas flow passage through the mill;
means for supplying gas at a predetermined rate to the inlet of the mill for passage through the mill;
a sensing means extending within the interior of the mill into the gas stream moving through the mill, said sensing means being responsive to the density of materials in said gas stream to produce a signal; and, means external of the mill and operably connected to said sensing means to receive a signal from said sensing means to produce an analog signal proportional to the density of the material sensed by said sensing means.
means for supplying gas at a predetermined rate to the inlet of the mill for passage through the mill;
a sensing means extending within the interior of the mill into the gas stream moving through the mill, said sensing means being responsive to the density of materials in said gas stream to produce a signal; and, means external of the mill and operably connected to said sensing means to receive a signal from said sensing means to produce an analog signal proportional to the density of the material sensed by said sensing means.
8. A roller mill according to claim 7 wherein said analog signal proportional to the density of the material that has been sensed is applied to an indicating means operable to provide a usable indication of the proportional analog signal.
9. The method of monitoring the operational performance of a roller mill having an air flow inlet and outlet;
comprising the steps of:
sensing the density of materials in the air flow stream, moving through the roller mill between the inlet and outlet;
producing an electrical analog signal indicative of said sensed density; and providing an indication of said electrical signal.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
comprising the steps of:
sensing the density of materials in the air flow stream, moving through the roller mill between the inlet and outlet;
producing an electrical analog signal indicative of said sensed density; and providing an indication of said electrical signal.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
10. The method of monitoring the operational performance of a roller mill having material feeding means and a gas flow inlet and outlet for directing a flow of gas through the mill, comprising the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill;
B) sensing the density of materials in the gas flow stream passing through the mill and producing a signal, C) supplying the signal to a signal conditioner to produce current which is proportional to the density of the material sensed; and D) applying the produced current which is proportional to the density of the material sensed to a read out.
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill;
B) sensing the density of materials in the gas flow stream passing through the mill and producing a signal, C) supplying the signal to a signal conditioner to produce current which is proportional to the density of the material sensed; and D) applying the produced current which is proportional to the density of the material sensed to a read out.
11. The method of monitoring the operational performance of a roller mill having a gas flow stream passing through the mill; comprising the steps of:
A) inserting a transducer into the gas stream to sense the density of material in the gas flow stream passing through the mill to produce a signal;
B) applying the signal produced to a signal conditioner to produce a D.C. current proportional to the density of the material that has been sensed; and, C) applying the D.C. current to read out.
A) inserting a transducer into the gas stream to sense the density of material in the gas flow stream passing through the mill to produce a signal;
B) applying the signal produced to a signal conditioner to produce a D.C. current proportional to the density of the material that has been sensed; and, C) applying the D.C. current to read out.
12. The method of monitoring the operational performance of a roller mill having an air flow inlet and an air flow outlet; comprising the steps of:
exhibiting the capacitance between a sensor and its quiescent surrounding within the mill; and, indicating the exhibited capacitance on a meter wherein such indication is proportional to the density of material in the air flow stream.
exhibiting the capacitance between a sensor and its quiescent surrounding within the mill; and, indicating the exhibited capacitance on a meter wherein such indication is proportional to the density of material in the air flow stream.
13. The method of monitoring the operational performance of a roller mill having material feeding means and a gas flow inlet and outlet for directing a flow of gas through the mill; comprising the steps of:
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill:
B) sensing the density of the materials in the gas flow stream passing through the mill as the mill is operating;
C) producing a signal which reflects the density of the material in the air flow stream which is being sensed;
D) supplying the signal to a signal conditioner to produce current which is proportional to the density of material sensed;
E) applying the produced current to a meter to activate the meter; and, F) utilizing the indicated data from the meter to control the operation of the mill.
A) supplying a flow of gas at a predetermined rate to the gas flow inlet of the mill:
B) sensing the density of the materials in the gas flow stream passing through the mill as the mill is operating;
C) producing a signal which reflects the density of the material in the air flow stream which is being sensed;
D) supplying the signal to a signal conditioner to produce current which is proportional to the density of material sensed;
E) applying the produced current to a meter to activate the meter; and, F) utilizing the indicated data from the meter to control the operation of the mill.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US63617075A | 1975-11-28 | 1975-11-28 | |
| US636,170 | 1975-11-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1085020A true CA1085020A (en) | 1980-09-02 |
Family
ID=24550734
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA261,129A Expired CA1085020A (en) | 1975-11-28 | 1976-09-14 | Roller mill performance monitoring by density sensing |
Country Status (5)
| Country | Link |
|---|---|
| AU (1) | AU507218B2 (en) |
| BR (1) | BR7607944A (en) |
| CA (1) | CA1085020A (en) |
| DE (1) | DE2653636A1 (en) |
| MX (1) | MX144277A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10052635B2 (en) | 2012-07-19 | 2018-08-21 | Thyssenkrupp Industrial Solutions Ag | Comminution of grinding stock in a vertical roller mill |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU620620B2 (en) * | 1988-05-27 | 1992-02-20 | Ical Limited | Device for the removal of non-combustibles from mills |
| JP6060499B2 (en) * | 2012-03-01 | 2017-01-18 | 株式会社Ihi | Biomass mill |
| JP7175601B2 (en) * | 2017-11-02 | 2022-11-21 | 三菱重工業株式会社 | Pulverizer and operation method of the pulverizer |
| CN108160225A (en) * | 2017-11-24 | 2018-06-15 | 杭州富阳富申颜料有限公司 | A kind of superfine iron oxide is red and preparation method thereof |
| CN112452448A (en) * | 2018-08-08 | 2021-03-09 | 李娜 | Energy-conserving vertical mill that building engineering used |
-
1976
- 1976-09-14 CA CA261,129A patent/CA1085020A/en not_active Expired
- 1976-11-23 AU AU19895/76A patent/AU507218B2/en not_active Expired
- 1976-11-25 DE DE19762653636 patent/DE2653636A1/en not_active Withdrawn
- 1976-11-26 BR BR7607944A patent/BR7607944A/en unknown
- 1976-11-26 MX MX16717676A patent/MX144277A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10052635B2 (en) | 2012-07-19 | 2018-08-21 | Thyssenkrupp Industrial Solutions Ag | Comminution of grinding stock in a vertical roller mill |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2653636A1 (en) | 1977-06-08 |
| MX144277A (en) | 1981-09-23 |
| AU1989576A (en) | 1978-06-01 |
| BR7607944A (en) | 1977-11-08 |
| AU507218B2 (en) | 1980-02-07 |
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