Note: Descriptions are shown in the official language in which they were submitted.
~Z~3~
The present invention relates in general to ~low sensing
apparata and in particular to such apparata which are cooperatively
arranged with a coal processing plant cyclone in order to determine
the presence of a flow stream from the cyclone outlet.
One very important stage in the mining and sorting of coal is
the coal processing plant. As the coal is initially mined, pieces
of rock become mixed with the coal and the mixture must be sorted.
In certain instances, the coal is separated from the rock by means
of a device called a cyclone. Any one coal processing plant may
have a large number of such cyclones depending upon the volume of
raw coal received. The type of cyclone employed in these processing
plants operates as a separator between particles or pieces of one
density (weight) and particles or pieces of a different density. By
sorting the pieces according to size, density becomes the
controlling factor of weight differential. The lighter pieces
~coal) pass upwardly while the heavier pieces (rocks) pass
downwardly. Consequently, it is important that the incoming mixture
of coal and rock be crushed and sorted as to size before being
introduced into a corresponding cyclone.
After the raw coal from the coal mine is crushed and then
separated as to the size of rock and coal, several cyclones may be
required to accommodate the various size groupings. Each coal and
rock mixture is next mixed with water and directed into a
corresponding cycLone under substantial pressure. While this slurry
rotates around the body of the cyclone in a centrifugal manner, the
heavier rock moves downwardly to an exit location and ~he lighter
coal moves upwardly out oE the top of the cyclone. Tbe water and
rock mixture exits the cyclone in a somewhat continuous flow manner
3~
and although this flow may be irregular in nature, it is critical to
the operation of the cyclone that blockage of this cyclone outlet be
identified at once. If blockage does occur, the operator must be
able to tell so immediately in order to take the necessary
precautionary steps and preclude rock and water from mixing with the
pure coal that passes out the top of the cyclone.
At the present time, there is not believed to be any suitable
means to sense when blockage occurs and to advise the operator of
this fact. Consequently, in many present-day systems, rock will in
fact mix with and thus pollute the otherwise relatively pure coal
exiting from the top of the cyclone. If such polluting occurs for
any length of time, the output product of the processing plant is
substantially damflged. Although flow detection sensing systems are
known to exist in the art as patented systems, none are specifically
designed for sensing the outlet flow from a coal processing plant
cyclone. Inasmuch as this particular type of Elow stream sensing
has a number of specific and unique requirements, any suitable flow
sensing system must be specifically designed to accommodate these
various uniquenesses. Listed below are potentially relevant
references which offer some indication of the types of detection
systems which have been conceived.
Patent No. Patentee Issue Date
2,798,215 Domingo et al.7/02/57
3,445,834 Street et al.5/20/69
3,686,926 Miller et al.8/29/72
3,878,103 Miller et al.4/15/75
4,103,292 Haas 7/25/78
3~
3,849,723 Allen 11/19/74
3,557,616 Landon, Jr. et al. 1/26/71
Domingo et al. discloses a liquid detecting device which relies
upon the electrical conductivity of the liquid for its operation.
Two conducting rings~ separated by insulating rings, are disposed in
an outlet pipe and these two conducting rings are electrically
coupled to a plug-in jack which is cooperatively arranged with a
temperature~ e indicating mechanism.
Street et al. discloses a liquid monitoring apparatus for
detecting the existence of a flowing liquid in a pipe, the apparatus
having laterally spaced probes adapted for axial insertion ioto the
pipe. One probe is disposed at a low level in the pipe, the other
probe is central. Only when there is sufficient Elow through the
pipe is the distance of separation bridged by the flo~ing liquid and
an indicating circuit activated.
Miller et al. ('92~) discloses a chip detecting and monitoring
device for detecting conductive and nonconductive ~aterial present
in a fluid system line. A woven screen of parallel conductive wires
and perpendicu]ar nonconductive wires is electrically coupled to a
battery source and light. When a conductive particle bridges two
adjacent conducting w-ires, the light is illuminated.
Miller et al. (i103) discloses a metal chip detecting and
monitoring device similar to the above-mentioned Miller et al.
('926) device. This particular reference is a continuation of a
divisional of the earlier reference and thus provides no new subject
matter.
~Q~36i
Haas discloses a material sensing device for sensing the level
or the Elow of solids such as grain, gravel or crushed stone. The
device includes a flexible hose secured within a junction box with a
light-sensitive diode at one end oE the hose and a light emitting
diode at the opposite end. A positive flexure of the hose as
produced by material contact causes an attenuation that is able to
be sensed.
Allen discloses a method and apparatus for measuring t~e
electrolytic conductivity of the liquid wherein a dialectric
sorption medium is employed to conduct the liquid from an
accessible, exposed portion into operative contacting association
between a pair of spaced contact electrodes.
Landon, Jr. et al. discloses a pa-rticle flow sensing device
which includes piezoelectric means supported on and activated by an
elongated member placed in the flow path of a particle-entrained
flow. An electrical signal being produced in response to impact of
the particles on the elongated member.
While these various disclosures may be considered as relevant to
the present invention, the closest disclosure is believed to be that
of the Landon, Jr. et al. reference. However, the ~andon device
involves a means to sense particle flow by radial compression of one
side of a piezoelectric cylinder. The compressive force is caused
by solid particles striking an elongated member extending across the
majority of the diameter of the flow conduit. Although the Landon,
Jr. et al. reference is believed to be the most relevant of those
above-listed patent disclosures, the Landon, Jr. et al. device
relies upon particle con-tact for mechanical sensing in lieu of
electrical contact.
3~
A Eurther dif~erence between the present invention and al:L o~
the above-listed references is that none o~ these references involve
sensing oE the Elow exiting from a coal processing plant cyclone.
While it may be argued that flow sensing is in fact only flow
sensing and it makes little difference what the associated apparatus
is, it should be understood that there are various aspects to coal
process plant operation which establish certain requisites for any
flow sensing apparatus. First, due to the fact that the processing
plant operator is having to keep track of many operations at one
time, his review of the operator control panel presents a myriad of
lights, gauges and buttons and it would be an improvement to provide
a flashing or flickering light as an indication of a properly
flowing exit stream from each cyclone. Such a flickering or
flashing light is an improvement visually to the operator and
provides a type of dynamic indication of the nature of the exiting
Elow at any instant of time. A further benefit to be afforded the
operator is a warning alarm sound such that when flow ceases for a
predetermined interval of time, even though the light may be
constantly on, the operator is able to hear the warning and know
that flow has stopped and may then shut down the cyclone so as to
prevent rock from backing up and polluting the exiting pure coal.
In addition to the above-listed patent references, another item
of possibly relevant technology is known to exist, yet sufficient
details are not known to be able eo discuss all aspects. This
other, possibly relevant technology pertains to the design and
operation of a scanning system employed at one time by Krebs
Engineers of Menlo Park, California. This scanning system used a
switch assembly positioned to intersect the exiting flow stream from
~2~ 36
a cyclone, and the switch assembly used is a mercury switch ~paddle-type).
It is known that this system never performed satisfactorily, possibly because
of the disadvantages provided by use of a mechanical switch.
A flow sensing apparatus for providing an indication of the presence
of an irregularly flowing flow stream from an outlet according to one embodi-
ment of the present invention comprises an electrical contact probe member
disposed in the flow stream, a sensing circuit cooperatively arranged with the
probe member and adapted to rapidly provide a sequence of two different elec-
trical signals, a first signal being generated by the sensing circuit when
the stream makes contact with the probe member and a second signal being gen-
erated by the sensing circuit when the stream does not make contact with the
probe member and a display light cooperatively arranged with the sensing circuit:Eor indicating the presence of the irregularly flowing stream, the display
light switching on in response to one of the first or second signals and
switching off in response the other signal so as to produce a flickering light
indicating the dynamic conditions of the irregularly flowing stream.
One object of the present invention is to provide an improved :Elow
sensing apparatus.
Related objects and advantages of the present invention will be
apparent from the following description.
Figure 1 is a diagrammatic, front elevation view of a flow sensing
apparatus in combination with a coal processing plan~ cyclone according to a
typical embodiment of the present inventionO
Figure 2 is an electrical schematic of the Figure 1 flow sensing
apparatus.
~2~ 33'~
For the purposes of promoting an understanding of the principles
of the invention, reference will now be made to the e~bodiment
illustrated in the drawings and speciEic language will be used to
describe the same. It will nevertheless be understood that no
limitation of the scope of the invention is thereby intended, such
alterations and Eurther modlfications in the illustrated device, and
such further applications of the principles of the invention as
illustrated therein being contemplated as would normally occur to
one skilled in the art to which the invention relates.
Referring to FIG. 1, there is illustrated a flow sensing
apparatus 20 cooperatively arranged with a coal processing plant
cyclone 21 for indicating the presence of a flow stream ~spray) 22
exiting from cyclone outlet 23. Apparatus 20 includes an electrical
contact sensing probe 24 positioned in the outer edge of the Elow
stream, a sensing circuit 25 and a display light 26. Although the
probe and display light are illustrated as being remote from sensing
circuit 25, it should be clear from the schematic of FIG. 2 that
these three subassemblies of apparatus 20 are all part of the same
system but are physically separated (FIG. 1) due to their preferred
locations relative to the operation of the coal processing plant
cyclone 21.
The raw coal from a coal mine which is received at the
processing plan~ comes mixed with rock. Due to present mining
techniques, the presence of rock with the coal is virtually
unavoidable. While processing plant cyclones are used to separate
the rock from the coal, there are initial processing steps which
must take place. First, the rock and coal mixture must be crushed
and then sorted as to particle (piece) size. ~ach of the various
~3 ~
particle s;ze m;xtures a-re then combined with water and introduced
under pressure into a corresponding cyclone 21. It is to be
understood that cyclone 21 represents only one cyclone of what may
be many cyclones in any one coal processing plant. The illustrated
cyclone is disposed vertically and is intended Eor relatively small
pieces of coal and rock. Larger pieces of coal and rock are
introduced into cyclones which are tilted at an angle oE
approximately 45 degrees.
The coal, rock and water mixture is introduced into the body 30
of the cyclone through inlet pipe 31, and since the density of rock
is greater than that of coal, the somewhat similarly sized pieces oE
rock and coal are sorted by the cyclone's centrifugal action due to
their weight differences. The heavier pieces of rock move
downwardly through the cyclone ultimately exiting at outlet 23 with
the water and this rock and water mixture forms flow stream 22. The
lighter coal moves upwardly out of the top oE the cyclone by means
of passageway 32. Due to the potential problems caused if outlet 23
becomes blocked, and in view of the likelihood of such blockage, it
is important Eor the cyclone operator, who is normally at a remote
location, to be able to have some warning oE or means for signaling
Elow stoppage. Further, it is also important Eor the operator to be
able to tell when flow is occurring in a normal manner. The use oE
sensing apparatus 20 provides a constant indicator of proper flow as
well as a warning alarm if flow ceases for a predetermined interval
of time. The indication of proper flow as well as the warning means
are fully disclosed by the circuit schematic set Eorth in FIG. 2.
Due to the abrasive nature of the exiting flow stream, the
sens;ng probe must be very durable as well as strong. While there
3~;;
are any number of mechanical means to secuFely position the sensing
probe in the flow stream, material selection becomes ~uite
important. A very rigid and abrasive-resistant material is best,
such as, for example, carbide. In the exemplary embodiment, a
carbide drill bit is used as the sensing probe. Since the present
invention operates on the basis of electrical potential of the
probe, as controlled by the presence of the flow stream, the
mechanical aspects of the probe's connection to the remainder of the
apparatus are not critical. This is in contrast to tbose systems
such as that of U. S. Patent No. 3,557,616 (Landon, Jr. et al.)
where the mechanical relationship of the probe to the other portions
of the device is very important. Further, this single~piece,
electrically conductive probe eliminates all durability and
reliability problems which plague the use of mechanical switches
(such as mercury switches) which might be cooperatively arranged
with the flow stream, such as by a paddle to activate the switch.
Referring then to FIG. 2, probe 24 represents the sensing probe
of FIG. 1. However, since many cyclones (up to twelve) are
simultaneously operable with a single sensing circuit 25, phantom
boxes 40a-40k represent eleven additional circuit portions
equivalent in all regards to the portion illustrated in detail as
portion 41. Probe 24 is coupled to a three-position switch 42
(including on, test, and off) which in turn is coupled to amplifier
43 which may be, for example, a CMOS 4850. The output of amplifier
4~ is coupled to light-emitting diode 26 (the display light of FXG.
1) .
~ ith sensing probe 24, properly positioned relative to outlet
23, when a water ar~d rock mixture of a normal flow volume is
d;scharged from the outlet (Elow stream 22), light 26 flickers in a
rapid, irregular sequence. Such flickering is caused by the
irregular;ty of the flow stream and the nonhomogenous nature of the
rock and water mixture. As this mixture intermittently and
irregularly contacts probe 24, the probe is placed into either a
high or low potential. When the flow stream is not hitting the
probe, the probe is pulled up to a positive potential (high~ through
resistors 44 and 45 placing a high on the input (pin 3) of amplifier
43. This causes the output of amplifier 43 (pin 2) to go high which
turns on (illuminates) display light 26. When the Elow stream is
h;tting ~he probe, the probe is pulled low (negative potential)
creating a low at both pins 3 and 2 of amplifier 43 and light 26
remains dark (off).
When pin 3 of amplifler 43 is at a high level, the line through
switching diode 48 is a]so at a high level turning on transistor 49
and turning off transistor 50 via diode 51. Capactitor 52 begins to
charge slowly by way of resistors 53, 54 with the time adjustment
being afEorded by resis~or 54. As the voltage at capacitor 52
increases, the level at the base oE transistor 57 increases and the
output of transistor 57 goes from low to high at the same rate as
t~e charging of capacitor 52. As the output oE transistor 57 goes
from low to high, transistors 58, 59 and 60 are activated.
Transistor 54 turns on light-emitting diode 61 while transistor 58
turns on transistor 60. Transistor 60 energizes relay 62 which
completes the alarm circuit through oscillator 65 ~an LM556GM)
causing spea~er 66 to sound.
When the flow stream is hitting probe 24, its potential is
brought to a low level which causes the input of amplifier 43 to go
~ 6
Low as well as the output (pin 2) which turns off LED 26 and
switches diode 48. The switching of diode 48 causes transistor 49
to turn oEf and transistor 50 to turn on through resistor 67 which
short-circuits both capacitor 52 and the base of transistor 57 to
~round, instantly. Correspondingly, transistors 57, 58 and 59;
relay 62; speaker 66, and LED's 61 and 68 are turned off. Thus, as
probe 24 is alternately, although irregularly, contacted by the flow
stream, indicator light 26 flickers on and off. Further, iE there
is a sufficient interval of time when the flow st-ream is not hitting
the probe, the "alarm" portion of the circuit (that portion from
transistor 49 to speaker 663 is activated as a warning to the
operator that blockage to the flow stream has occurred. This alarm
portion of the circuit is important because oE the possibility that
the operator may not be able to keep track of how long the indicator
light 26 is in a constantly on condition, created by flow blockage~
The flickering of this light provides a dynamic indication of the
flow and is easily visible by the operator, the light may stay on
for a few seconds and not represent a flow blockage condition.
However, if the operator does not ascertain when the light flrst
went on and how long it has been on, a more major flow blockage
condition could be resulting and the operator would not be aware of
the problem. This ;s the reason for the alarm portion of the
circuit.
Circuit section 71 is an instant off, time-delay (adjustable) on
circuit section including switch 72, resistors 73 and 74, capacitor
75 and transistor 76. When switch 72 is depressed, capacitor 75 is
energiæed and the base of transistor 76 goes high, closing the
transistor and placing the collector o~ transistor 76 at a low
~ 3 ~
potential, The connection of the collector o~ transistor 76 to the
base of transistor 58 means that when transistor 76 is on,
transistor 58 is ofE. Thus, c;rcuit section 71 is able to be used
as a main switch for turning off the speaker (silencing the alar~)
as an alternative to individually placing all of the probe switches,
such as 42, into an "off" position.
Circuit section 80 represents the power supply means for the
present invention. An external 120-volt AC source is coupled by way
of fuse 81 to transformer ~2 and from there to diode bridge 83. The
arrangement of capacitors in combination with 12-volt, voltage
regalator 84 provides a positive 12-volt DC regulated potential on
line 85.
Due to the possible variations in electronics as caused by
individual part tolerances, and in view of the variable nature of
the exiting flow stream, adjustable resistor 44 permits varying of
the pick-up sensitivity of the probe. Further, each probe in the
group of probes 1-12 is able to be individually adjusted to a
precise pick-up sensitivity by the corresponding adjustable
resistor. While the present flow sensing apparatus and in
particular, the sensing circuit has been disclosed in the
environment of a coal processing plant and has been cooperatively
arranged with a separating cyclone, it is to be understood that the
electronics and the sensing concept disclosed herein are in fact
applicable to other situations and uses.
While the invention has been illustrated and described in detail
in the drawings and Eoregoing description, the same is to be
considered as illustrative and not restrictive in character, i-t
being understood that only the preferred embodiment has been shown
3~;
and described and that all changes and modiEica~ions that come
within the spirit of the invention are desired to be protected.
