U.S. patent application number 10/056012 was filed with the patent office on 2003-07-31 for industrial flame sensor communication system.
Invention is credited to Eley, John D., Wild, Gary G..
Application Number | 20030143503 10/056012 |
Document ID | / |
Family ID | 27609257 |
Filed Date | 2003-07-31 |
United States Patent
Application |
20030143503 |
Kind Code |
A1 |
Wild, Gary G. ; et
al. |
July 31, 2003 |
Industrial flame sensor communication system
Abstract
A communication and data interpreting system for detecting and
converting and combining multiple analog signals from flame
detectors into a single analog signal and RS 485 for transmission.
This system also uses an analog clamping circuit to generate the
analog signal from flame rod sensors and a load resistor and a high
voltage generator for generating the signal in an UV sensing tube.
The input signals are then multiplexed and sent to a microcomputer.
The microcomputer uses a diode and a solid state relay circuit to
generate a compatible signal output to a burner control.
Inventors: |
Wild, Gary G.; (Rockford,
IL) ; Eley, John D.; (Beloit, WI) |
Correspondence
Address: |
JOHN ELEY
GN ELECTRONICS, INC
SUITE 104
9958 N. ALPINE RD.
MACHESNEY PARK
IL
61115
US
|
Family ID: |
27609257 |
Appl. No.: |
10/056012 |
Filed: |
January 28, 2002 |
Current U.S.
Class: |
431/69 |
Current CPC
Class: |
F23N 5/123 20130101;
F23N 2223/02 20200101 |
Class at
Publication: |
431/69 |
International
Class: |
F23N 005/00 |
Claims
What is claimed is:
1. A communication system for a plurality of flame sensors in a
single or multiple burner system with a connection required between
the sensors at a remote location and the burner control or
controls, comprising in combination a transmitting module each
having an input for connection to a flame sensing transducer
exposed to a flame to be sensed, each having an output for
producing an electronic level signal indicative of the sensed flame
or group of sensed flames; a receiving module for receiving the
information from the transmitting module upon detection of a flame
or loss of a flame from a burner or extinguished burner and
identifying the identity of the burner or extinguished burner and
the time at which the burner is established or extinguished; a
display module with memory means associated with the processor for
displaying the signal status of each flame transducer and recording
status information at the time of occurrence of loss of signal
condition, the status information including the identity of any
extinguished burner and the time at which said extinguished burner
extinguished.
2. The combination of claim 1 wherein the electronic programmable
processor includes manually settable means for specifying the
number of flame sensors in a particular system.
3. The combination as set forth in claim 1 wherein the memory means
includes non-volatile memory means for storing status information
on the system, the nonvolatile memory means having sufficient
capacity to store information on all burners and maintain said
storage in the event of power failure upon system shutdown.
4. The combination as set forth in claim 1 in which each flame
sensor input to the transmitting module includes an output signal
at the receiving module associated with a sensing transducer when
the sensing transducer detects a flame, the output signal
corresponding to the output signal from the sensing transducer and
capable of interfacing to the corresponding burner control for the
sensing transducer.
5. The combination as set forth in claim 1 wherein the memory means
includes a plurality of words of storage for storing information
regarding system faults as they are detected for later scanning of
the stored fault information to detect patterns therein.
6. The combination as set forth in claim 1 in which the control
system includes a flame watchdog timer triggered by the processor
and having an output serving as an enabling signal for fault relay
which enables the flame sensing output.
7. The combination as set forth in claim 6 in which a flame present
signal generated by the transmitting module when polling the flame
sensors is operatively associated with the flame watchdog timer to
enable the flame watchdog timer to respond to trigger pulses from
the processor only in the presence of the flame present signal.
8. The combination as set forth in claim 8 wherein the flame
watchdog timer has a reset input, and means coupling the reset
input to the processor for enabling the flame watchdog timer in a
normal mode to sense the flame present signal and provide an output
signal to the transmitting module
9. The combination as set forth in claim 8 including a further
watchdog timer having a trigger input connected to the
microcomputer for being serviced periodically within the time
constant of the further watchdog timer, an output from the further
watchdog timer being connected to a fault relay for control
thereof, the output of the watchdog timer serving to energize the
fault relay and terminate the flame present signal in the event the
further watchdog timer is not triggered by the processor.
10. The combination as set forth in claim 1 including an
analog-to-digital converter associated with the processor and with
the flame sensors, a multiplexer connected to an analog signal from
the flame sensors indicative of flame quality, and having an output
connected to the analog-to-digital converter for digitizing flame
quality signals and passing them to the processor for storage.
Description
REFERENCES CITED (RELATED APPLICATIONS) U.S. Pat. Nos. 3,266,026
August, 1966 Plambeck 340/228. 3,437,884 April, 1969 Mandock et al.
317/148. 3,500,469 March, 1970 Plambeck et al. 3401228. 3,817,687
June, 1974 Cavalleroetal. 431/202. 3,905,126 September, 1975
Villalobos et al. 34/72. 4,000,961 January, 1977 Mandock 431/2.
4,815,965 March, 1989 Linkins, Jr. 431/75. 4,938,684 July, 1990
Karl et al. 431/75. 5,026,272 June, 1991 Takahashietal. 431/79.
5,077,550 December, 1991 Cormier 431/79. 5,161,963 October, 1992
Berlincourt 431/78. 5,203,687 April, 1993 Oguchi 431/76. 5,249,954
October, 1993 Allen et al. 431/75.
ADDITIONAL REFERENCES
[0001] "Flame Worxs", brochure of Fireye, Inc in Derry N.H.
[0002] "Sens-A-Flame II Single-& Multi-Burner Combustion
Safeguard", brochure of Pyronics, Inc. in Cleveland, Ohio.
[0003] "Electronic Flame Monitoring", brochure of Pyronics, Inc. in
Cleveland, Ohio.
BACKGROUND OF THE INVENTION
[0004] Numerous industrial processes utilize combustion units, such
as, for example, furnaces, ovens, incinerators, dryers, and
boilers. Typically these types of equipment have more than one
burner each operating with various fuels. Each of these burners is
equipped with some type of flame sensor. The flame sensors are
always mounted on the burner in such a way that the sensor is able
to detect a flame when one is present in the burner. The sensor
then generates a signal, which is detected by a burner control
system. The burner control in turn governs the start up and shut
down of the burner according to a prescribed sequence. The purpose
of this is to avoid the possibility of explosions and other
failure, which could result in damage or injury to equipment or
personnel. There are different types of sensors in use in
industrial burner applications. These include Flame rod and
Ultra-violet sensors.
[0005] Flame rod sensors work on the principle of flame
rectification. This principle is based on the fact that the flame
in a burner is electrically conductive when a voltage is applied
across two electrodes in the flame. Heat from the flame produces
increased activity in the molecules between the electrodes. This
increased molecular collisions, as a result of this activity,
causes ions to be freed from the molecules. This principle is
called flame ionization. The freed electrons are then capable of
moving to the electrodes, which are electrically charged. The
positive ions going to the negative electrode and the negative ions
going to the positive electrode. If the electrodes in the flame
have a different area the more ions will flow to one electrode that
the other. In a flame rectification system the area of the grounded
electrode is at least four times larger than that of the flame rod
electrode which is connected to an alternating voltage source.
Because of the differences in electrode areas more current flows in
one direction than the other direction. This difference in current
flow creates a pulsating direct current, which is detected as a
flame present signal by the burner control.
[0006] Ultra-violet sensors do not actually come in contact with
the flame in a burner as do flame rod electrodes. The Ultra violet
flame detection system that employs a specialized sensor which
detects the ultraviolet light radiated from a flame but is
insensitive to other ranges of emitted light such as visible or
infrared light. The typical Ultraviolet flame sensor is a sealed
quartz glass tube filled with a type of a gas and containing two
electrodes (anode and cathode). A high voltage is applied across
the electrodes by the burner control. When the sensing tube becomes
exposed to Ultraviolet light in the presents of the voltage
presence across the electrodes, electrons are emitted from the
cathode. These electrons ionize the gas in the tube and the gas
becomes conductive. Current then begins to flow across the
electrodes and the voltage potential drops. When the voltage
potential drops far enough the conduction stops. This causes the
voltage to rise again. If Ultraviolet light is still present from
the flame the conduction process will start again when the voltage
has risen far enough. This continual sequence results in a series
of pulses emitted from the sensor when a flame is present. This
series of pulses is then detected as a flame present signal by the
burner control.
[0007] Because of the nature of the flame signal produced by the
sensors described above the nature and method of connections
between the sensor and the burner control has always been critical
in the operation of the overall burner control system.
[0008] Each sensor is controlled and monitored by an individual
circuit contained in the burner control unit. The wires used to
carry the signal from the sensor to the control must be kept apart
from any sources of electrical energy, which could disrupt the
signal and cause an unwarranted shutdown of the burner system.
[0009] This type of shut is not only inconvenient but can be costly
in terms of lost production time and sometimes product.
[0010] In many installations of furnaces, oven and other equipment
using burners the burner controls are installed in an
environmentally controlled control room. This control room could be
as much as several hundred feet away from the physical location of
the burners being controlled. This results in very long runs of
expensive cabling and conduit to bring the signals from the sensors
back to the control room. Even when such cabling and installation
techniques are used to reduce the effects of electrical
interference, the sensor signals themselves may attenuate to the
point where the burners cannot run reliably. What is needed in
industrial burner systems is means for communicating the flame
sensor signal from the sensors to the burner controls, which
improves the effectiveness and flexibility of burner control
systems.
SUMMARY OF THE INVENTION
[0011] In view of the aforementioned discussion, the present
invention provides a communication system and method which provide
a reliable means through which the information contained in a flame
sensor signal or many flame sensor signals can be reliably
transmitted over long distance using a single pair of wires. This
invention will also provide a system and method for combining
several flame sensor signals into one signal, which can be
interfaced to a burner control as a single sensor system.
[0012] This is done through a unique method of multiplexing the
inputted sensor signals into the invention and capturing the
relevant information required for the burner control. This
information is then converted to a single or multiple sensor
signals, which can be interfaced to a burner control for operation
of the burner system. This information is also converted into a
RS485 signal and transmitted over an effective distance of 3000
feet where in is converted by another module of the invention into
multiple or single flame sensor signals which the burner control
will recognize.
[0013] In addition to this, other objectives and advantages of the
invention will become more apparent from the following detailed
description when taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The accompanying drawings illustrate the aspects and
concepts of the invention. In the drawings:
[0015] FIG. 1 is a block diagram of the invention concepts
incorporating several new concepts in the process. The invention is
made of several unique modules, which will be described in detail
below
[0016] While the invention will be described in connection with
certain preferred embodiments, there is no intent to limit it to
those embodiments. On the contrary, the intent is to cover all
alternatives, modifications and equivalents as included within the
spirit and scope of the invention as defined by the appended
claims.
DETAILED DESCRIPTION OF THE PERFERRED EMBODIMENTS
[0017] In the drawing labeled FIG. 1 the power supply 100 supplies
the 5 volts and the 12 volts required to operate the electronics.
The UV powers supply 102 provides power in the form of high voltage
to energize the ultraviolet sensors connected to the system.
[0018] Flame Rod Sensing
[0019] The line voltage, which is supplied to the power supplies,
is also supplying the capacitor C1 and the Analog Clamping Circuit
115.
[0020] The analog clamping circuit works with a unique principle.
Rather then supply high voltage using a transformer, as current
technology requires, this circuit uses 120 VAC (Line Voltage). The
key principle is combining the diode effect of the flame upon the
flame rod with C1 capacitor. This creates a clamping phenomenon and
a partial direct current, which is detected by the comparator
circuit contained in 115. The input multiplexer connects each of
the sensor inputs to the signal generating circuitry. The output of
the Analog clamping circuit 115 is connected to the Flame Rod
analog to frequency module 105. This module changes the analog
flame signal in to a frequency signal and sends it to the
opto-isolator 106. This frequency signal is then sent to the
microcomputer module 107 where it is interpreted as flame signal.
Since the microcomputer controls which sensor is being looked at by
the multiplexer, each sensor signal is individually identified.
[0021] Ultra-Violet Sensing
[0022] The Ultraviolet power supply 102 supplies the excitation
voltage to each of the 16 UV sensors which in turn are connected
one at a time by the multiplexer to the load RL. When a flame
signal is present a frequency pulse occurs at RL due to the UV
sensing phenomenon explained above. This frequency pulse is then
sent to the UV opto-isolator 104. This frequency signal is then
sent to the microcomputer module 107 where it is interpreted as
flame signal. Since the microcomputer controls which sensor is
being looked at by the multiplexer, each sensor signal is
individually identified.
[0023] The microcomputer 107 has several functions.
[0024] Firstly, the microcomputer module receives the frequency
signals from the UV ipto-isolator 104 and the Flame Rod
opto-isolator 106. When a flame signal is present at all the
connected sensors the microcomputer, the microcomputer creates a
combination flame output signal using the circuit 110. The circuit
in 110 is also a unique concept, which consisted of a solid state
switch and a rectifier circuit. By modulating the solid state
switch the microcomputer creates a frequency output signal with a
direct current component. This output signal is compatible with
both for UV and Flame rod type burner controls.
[0025] Second the microcomputer monitors all the components in the
overall system. The circuit test line verifies the flame signal
processing modules are functioning properly. In the event they are
not then the entire system will shut down.
[0026] The microcomputer also converts the information in each of
the sensor frequency signals into the RS485 communication format.
This allows the transmission of this data over great distances (up
to 3000 feet).
[0027] The DIP switch 109 is the operator interface, which
indicates to the microcomputer the total number of sensors,
connected (Flame rod, or Ultraviolet).
[0028] Turning now to the schematic drawing labeled Quanta-Max
Logic board. The watchdog is comprised of U9:A, U9:B, U9:D, and
four diodes. The Microcomputer sends pulses to the watchdog circuit
through C22 while it is running. If the microcomputer should freeze
or shut down and not send the pulses the output from U9:A would go
high and send a reset signal to the microcomputer on the reset
input. The DIP switches S3 and S2 set the configurable operational
parameters. They are connected to the microcomputer through the
parallel shift registers U17 and U16 and the SPI bus. U12 is the
EEROM which stores the non-volatile information needed by the
microcomputer U11. The circuit comprising U5 and U6 is the RS485
communication output device controlled by output PC7 of the
microcomputer.
[0029] Turning now to the schematic drawing labeled Quanta-Max
5003-01 M.S01. The step down transformer T1 receives 115 volts on
the primary. The secondary has two winding. One 5&6 is for
supplying power (+5V) to the microcomputer. The voltage is
rectified through U4 and filtered by C13. The second winding is
used for the analog power to the flame rod circuit generating +12V
and -12V through U20 and U19.
[0030] Turning now to the schematic drawing labeled Quanta-Max
5003-01 M.S02.
[0031] The circuit comprising D1, D3, D4, D5, D8, D9 and capacitors
C2, C3, C7, and C8 comprise the voltage multiplier creating the
voltage at UV (535VDC) ON THE SENSOR SELECT that supplies the
voltage to the UV sensing tube. If there is a jumper between the
center pin and the UV pin on SENSOR SELECT. The SENSOR line will
connect to one of 16 inputted UV sensors. The frequency of negative
pulses across C4 corresponds to the flame intensity. Through C4 the
sensor is connected to an opto-isolator. The output UVSIG connects
to the microcomputer input Tcap. When the jumper is between the
center pin and FR on SENSOR SELECT. The circuit comprising C29, D7,
D2, R1, R3, R7, R9 R4, R8 and U1:A is a voltage clamping circuit
used in conjunction with the "flame diode" effect from the flame
rod. The AC voltage is clamped through C29 and the "flame diode"
with a negative bias. The amount of this bias is proportional to
the amount of flame detected. The negative side of the bias is
measured relative to the positive side through D2 and the divider
R3 & R1. The positive side is measured through D2 and R7 &
R9. The negative side is filtered by C6 and the positive side is
filtered by C9. Negative and positive is combined and amplified by
the op amp U1. The output of U1 goes to a voltage to frequency
converter, which uses the formula shown at the bottom to determine
the frequency. The output of the frequency converter goes to the
microcomputer pin 2.
[0032] Turning now to the schematic drawing labeled Quanta-Max
5003-01M.S03. The switch SW1 determines the number of sensors
connected through a parallel to serial converter U8 and connects to
the microcomputer through the SDI bus. L1 and L2 are indicating
LEDs. L1 indicates that the output circuit is active and L1
indicates the Flame signal is present. The circuit comprising D21,
R68 and U15 is controlled from the microcomputer output Tcmp
through U9. When pulsed by the microcomputer this circuit creates a
pulsed DC output, which is equivalent to the DC current required by
a flame rod type burner control. The DC pulses are also equivalent
to the frequency pulse requirement of the Ultraviolet type burner
controls. This allows a unique interface to various burner controls
in the industry. The Fault Relay is a supervisory relay and will
open the output circuit in the event of a failure. The Flame Relay
is energized through Q2 in the event that a flame is detected. The
relay contacts are supervised through the opto-coupler U3 and the
rectifier U14.
[0033] Turning now to the schematic drawings labeled Quanta-Max
5003-01M.S04 and Quanta-Max 5003-01M.S05. OP3 through OP 16 are
solid state switches each activated by an opto-coupler controlled
by PA0-7 from the microcomputer. These are used to selectively
connect one of 16 sensors, one at a time into the sensor signal
processing circuit.
[0034] The entire system as described provided a level of
flexibility and reliability over a long distance, which the
industry does not have at present. This invention will receive the
input of multiple flame sensors, process that information and
produce a single or multiple output signals completely
indistinguishable to the burner control. In addition it provides a
communication means for transmitting the flame signal information
into a format readily acceptable to computers and distributed
control systems. The foregoing description of various preferred
embodiments of the invention has been presented for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed. Obvious
modifications or variations are possible in the light of the above
teachings. The embodiments discussed were chosen and described to
provide the best illustration of the principles of the invention
and its practical application to thereby enable one of ordinary
skill in the art to utilize the invention in various embodiments
and with various modifications as are suited to the particular use
contemplated. All such modifications and variations are within the
scope of the invention as determined by the appended claims when
interpreted in accordance with the breadth to which they are
fairly, legally, and equitably entitled.
* * * * *