CA2225483A1 - Ozone generator with in-line sensor - Google Patents
Ozone generator with in-line sensor Download PDFInfo
- Publication number
- CA2225483A1 CA2225483A1 CA002225483A CA2225483A CA2225483A1 CA 2225483 A1 CA2225483 A1 CA 2225483A1 CA 002225483 A CA002225483 A CA 002225483A CA 2225483 A CA2225483 A CA 2225483A CA 2225483 A1 CA2225483 A1 CA 2225483A1
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- Prior art keywords
- ozone
- output
- oxygen
- coupled
- control signal
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/10—Preparation of ozone
- C01B13/11—Preparation of ozone by electric discharge
- C01B13/115—Preparation of ozone by electric discharge characterised by the electrical circuits producing the electrical discharge
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/10—Preparation of ozone
- C01B13/11—Preparation of ozone by electric discharge
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2201/00—Preparation of ozone by electrical discharge
- C01B2201/20—Electrodes used for obtaining electrical discharge
- C01B2201/22—Constructional details of the electrodes
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2201/00—Preparation of ozone by electrical discharge
- C01B2201/90—Control of the process
Abstract
An apparatus for generating ozone from an oxygen supply. The apparatus comprising grids mounted in an enclosure and a high voltage circuit coupled to the grids for generating an electric field. The high voltage circuit receives AC power and includes a control circuit for producing a linearly controlled high voltage output from the AC feed for energizing the grids. The apparatus also includes an in-line sensor for determining the level of ozone being produced without affecting the ozone concentration. The high voltage circuit is also suitable for other applications where a precisely controlled high voltage output signal is needed.
Description
CA 0222~483 1997-12-22 OZO~nE ~P~r~R~TOR WII~ IN-LINE SE3NSOR
This invention relates to apparatus for generating ozone gas, and more particularly to an apparatus with an in-line sensor which is suitable ~or applications in which the concentration o~ ozone gas needs to be carefully controlled.
In the art, ozone generators are well-known.
United States Patent 5 052.382, which issued to Wainwright on October 1, 1991, describes an apparatus for the controlled generation and ~mi ni stration of ozone gas. The apparatus disclosed by Wainwright comprises a generator for generating the ozone, a monitor ~or monitoriny the ozone, a dosage device for providing the amount of ozone and a computer for controlling operation o~ the apparatus.
While Wainwright discloses an ozone generating apparatus suitable ~or medical application, there are aspects which a~ect the per~ormance and accuracy of the device. The monitor or sensor taught by Wainwright comprises an ultra violet light source and a strobed detector. The detector is strobed by a zeon light source, but according to Wainwright, it may be strobed by another light source. As will be understood by those skilled in the art, this arrangement comprises an intrusive measurement technique. According to this techni~ue, the ozone and oxygen gas stream is exposed to ultra violet light. The W light interacts with the ozone and the amount of W light which is measured by the sensor will be dependent on the concentration o~ the ozone gas. Because there is an interaction between the W light and the ozone gas, the W light a~ects the concentration o~ the ozone gas which is produced by the generator. There~ore, the ozone generator taught by Wainwright is not well-suited ~or applications where the ozone concentration must be very accurately controlled, nor is the Wainwright device suited ~or an application where the ozone sensor is in-line with the treatment.
CA 0222~483 1997-12-22 It is object of the present invention to provide an apparatus for generating ozone gas having an electronic circuit capable of carefully controlling the amount of ozone being generated. It is another object o~
the present invention to provide an apparatus for generating ozone gas having a non-intrusive sensor for sensing the concentration of the ozone gas being produced.
It is another object of the present invention to provide an ozone sensor which can be located "in-line" with the treatment path.
According to one aspect of the present invention, there is provided an apparatus for generating ozone from an oxygen supply, said apparatus comprising: (a) an enclosure having an inlet for receiving said oxygen supply and an outlet for releasing said ozone and said oxygen; (b) a plurality of grids mounted inside said enclosure and said grids being separated by plates; (c) energizer means for energizing said grids, said energizer means having a control input for receiving a control signal and an input port for connecting to a power source; and (d) said energizer means including generator means for generating a high voltage output coupled to said grids for energizing said grids and producing an electric field, and said generator means being responsive to said control signal.
According to another aspect of the present invention, there is provided a bridge network and control circuit for linearly controlling an AC signal. The apparatus for linearly controlling an AC signal comprising (a) a bridge network having an input port for receiving an AC signal, and said bridge network including a switching control input and a bridge output port; (b) a control circuit having an input for receiving a control signal and an output coupled to the switching control input o~ said bridge network, and said control circuit having means for CA 0222~483 l997-l2-22 generating a switching control signal at said output for switching said bridge network and producing a controlled power signal at said bridge output port; and (c) a trans~ormer having an output port and an input port coupled to the output port of said bridge output port and means responsive to said controlled power signal for producing a high voltage output signal at said output port.
Reference will now be made to the drawings which illustrate, by way of example, a preferred embodiment of the present invention, FIGURE 1 is a diagrammatic illustration of an apparatus according to a speci~ic embodiment of the present invention; and FIGURE 2 is a schematic diagram of the control circuitry for the embodiment shown in Fig. 1.
Reference is first made to Figure 1 which shows an ozone generator 1 according to the present invention. The ozone generator 1 is suitable for the generation of carefully measured amounts of ozone gas and has particular though by no means exclusive application to medical applications. The apparatus and particularly the control circuit have wider applicability, such as applications where high voltage needs to be carefully controlled.
As shown in Figure 1, the ozone generator 1 comprises a housing or enclosure 10. The housing 10 is formed from PTFE material co~monly known as Te~on~, preferably medical grade. Te~on is preferred because it is an inert substance which is impervious to ozone and preferably the housing 10 is milled from a solid block of CA 0222~483 1997-12-22 Teflon~. The housing 10 can also be made from Kynar~
material available from the Pennwalt Corporation and other compositions such as CPCVC or silicon which are of medical grade. As shown, the housing 10 includes a lid 12 which is also made from medical grade Te~on~. The lid 12 is attached to the enclosure 10 by secure fasteners 14, for example, precision screws. The enclosure 10 includes an inlet port 16 and an outlet port 18. The inlet 16 provides the input for oxygen gas 24 and is coupled to an oxygen supply tank 20 through a gas flow control valve 22. The gas flow control valve 22 is coupled to control circuit 32 through a stepper motor 23 or other appropriate actuator.
A ~ow meter 25 is also included which provides the rate of flow of the oxygen gas 24 into the enclosure 10. The outlet port 18 provides an output for gas 26 comprising oxygen and ozone produced by the generator 1. As shown in Figure 1, a temperature sensor 19 can also be provided to sense the temperature inside the enclosure 10. The control circuit 32 uses the temperature readings to control the production of ozone.
The ozone generator 1 includes a series of grids or electrodes 28a,28b,28c which are mounted in a spaced relationship inside the chamber 11 formed by the enclosure 10 as shown in Figure 1. Preferably, the grids or electrodes 28a,28b,28c are made from high-grade stainless steel. A pair of mica sheets 30a,30b separate the grids 28. The ozone generator 1 has a control circuit and power supply module 32. The control circuit 32 is powered by conventional AC power 34, i.e. mains supply.
The control circuit 32 has a high voltage output 36 which connects to the grids 28a,28b,28c. The control circuit 32 biases the grids 28a,28b,28c to a high voltage level to produce an electric field which causes the formation of ozone gas 03 in the stream of oxygen 24 which enters the chamber 11 through the inlet port 16 and passes over the electrodes 28. The circuit 32 uses the gas flow control CA 0222~483 1997-12-22 valve 22 to regulate the amount of oxygen 24 entering the chamber 11. The ozone generator 1 can also include a relay 33 (Figure 2) as a safety feature which is activated by the control circuit 32 to enable the high voltage feed to the electrodes 28.
Re~erence is next made to Figure 2, which shows the control circuit 32 in more detail. The control circuit 32 preferably comprises a microprocessor-based circuit suitably programmed for operating the gas ~ow control valve 22 and the ozonizer 1.
As shown in Figure 2, the control circuit 32 comprises a microcontroller 38, a high voltage drive circuit 40, a high voltage trans~ormer 42, and a sensing circuit 44. The high voltage drive circuit 40 is connected to the transformer 42 which produces the high voltage output for biasing the grids 28. The sensing circuit 44 is coupled to the output of the transformer 42 and is used by the microcontroller 38 to determine the amount of ozone gas 03 being generated as will be described below.
The high voltage drive 40 has an input 46 connected to an output port of the microcontroller 38 for receiving a control signal 48. The control signal 48 comprises a pulse train which is generated by the microcontroller 38. The high voltage drive circuit 40 as shown in Figure 2 comprises a bridge network 50 and a bridge control circuit 52. The bridge network 50 comprises four diodes 50a,50b,50c,50d connected in a bridge configuration. As shown in Figure 2, the bridge network 50 couples the "live~ AC voltage 34 to the primary winding of the high voltage transformer 42. The current ~owing in the primary winding of the transformer 42 is controlled by the circuit 52 which is coupled to the other port 54 of the bridge 50. The current which ~ows in the bridge 50 and primary winding induces a voltage in the secondary winding CA 0222~483 1997-12-22 of the high voltage transformer 42 which biases the grids or electrodes 28 ( Figure 1).
The function of the bridge network 5 0 and the bridge control circuit 52 is to regulate the current flowing in the primary winding and thereby the high voltage induced in the secondary winding of the transformer 42 and applied to the grids 28. By regulating the high voltage applied to the grids 28, the amount of ozone gas Q~ which is generated can be carefully controlled. As will be described, the bridge control circuit 52 together with the control signal 48 regulate both the shape and level of the high voltage signal which biases the electrodes 28, thereby providing accurate control for the production of ozone.
The bridge control circuit 52 comprises an input transistor 56, an isolation transformer 58 and an output transistor 60. The isolation transformer 58 is needed because the bridge network 50 iS "floating" at 110 VAC (or 220 VAC). The base of the transistor 56 forms the input 46 for receiving the control signal 48 from the microcontroller 38. The control signal 48 comprises a pulse train generated by the microcontroller 38. According to the invention, either the pulse width or the frequency of the control signal 48 can be varied to control the current flowing through the bridge 5 0 and the primary winding of the transformer 42. The pulse width (or frequency) of the control signal 48 iS selected to produce a target ozone level and the actual amount of ozone being produced is determined through the sensing circuit 44. The collector of the transistor 56 iS connected to the primary winding of the isolation transformer 58 so that the pulse train produced by the signal 48 is induced in the secondary winding of the transformer 58. The secondary winding of the transformer 58 is connected to a diode 62 and a capacitor 64. The diode 62 rectifies the output from the secondary winding of the isolation transformer 58 and CA 0222~483 1997-12-22 charges the capacitor 64 to yenerate a DC voltage. The base o~ the output transistor 60 is connected to the capacitor 64 through a resistive divider formed from resistors 66,68. Another resistor 70 is connected to the emitter of the transistor 60 to limit the current ~owing through the transistor 60. The values of the resistors are chosen to operate the output transistor 60 in the linear or active region. By operating the output transistor 60 in the active region, a sinusoidal output ~rom the bridge 50 is produced thereby allowing precision linear control of the voltage output from the secondary winding of the trans~ormer 42 which is applied to the grids or electrodes 28.
The sensing circuit 44 is coupled to the secondary winding o~ the high voltage transformer 42 and provides the microcontroller 38 with data for determining the amount o~ ozone gas 03 being produced. The microcontroller 38 uses this inform.ation to control the operation of the ozone generator 1. The microcontroller 38 can be programmed to respond to comm~n~ from another computer (not shown) or the microcontroller 38 can include an input panel (not shown) for m~nll~lly setting the desired ozone gas level.
Figure 2 also shows the sensing circuit 44 in more detail. The sensing circuit 44 produces an output signal 72 corresponding to the discharges occurring in the chamber 11 which are also related to the production o~
ozone gas 03 ~rom the oxygen 24. The microcontroller 38 uses the output 72 from the sensing circuit 44 to calculate the amount of ozone gas 03 being generated by the ozonizer 1. Each time there is a discharge between the electrodes 28 mounted in the cha-mber 11 (Figure 1), a pulse is produced in the winding o~ the high voltage transformer 42.
A pickup coil 74 is electromagnetically coupled to the winding of high voltage transformer 42 and pulses due to CA 0222~483 1997-12-22 discharges will induce a current in the pickup coil 74.
The sensing circuit 44 detects these pulses and produces the output 72 for the microcontroller 38.
Referring to Figure 2, the sensing circuit 44 comprises a diode 76, a capacitor 78, a resistor 80 and an operational amplifier 82. The operation amplifier 82 (op amp) is configured as a voltage follower or unity gain buffer and functions as an isolating circuit. The capacitor 78 is charged through the diode 76 by the induced voltage in the pickup coil 74 and provides an input voltage for the op amp 82. The op amp 82 produces a corresponding output pulse 72 which is inputted by the microcontroller 38. The microcontroller 38 includes program code which determines the amount of ozone 03 produced by the discharge by calculating the area of the pulse. The readings from the flow rate meter 25 are factored into the calculation.
Preferably the temperature inside the enclosure 11 is also taken into account, i.e. as the temperature inside the enclosure 11 rises the voltage to the grids 28 needs to be increased. If the stream of oxygen 24 comprises medical grade oxygen then there is a direct correspondence between the input energy and the amount of ozone 03 generated. If the oxygen 24 does not comprise medical grade oxygen, i.e.
pure oxygen, then a correction factor is introduced into the calculation.
A significant advantage of the sensing circuit 44 and microcontroller 38 arrangement according to the present invention is the capability to perform an ozone measurement ~lin-linel~. Because the measurement can be taken in-line, the problem of the ozone gas 03 being contaminated or altered by the measurement technique is eliminated.
CA 0222~483 1997-12-22 g The microcontroller 38 can be implemented using the commercially available PIC16C71 microcontroller available from Microchip Technologies Inc. which has been suitably programmed to perform the processing steps according to the present method. The PIC16C71 controller is a single chip device comprising a microprocessor and "on-chip" program memory, data memory, input/output ports, timers and other on-chip resources.
The control loop for controlling the operation of the ozone generator 1 is pre~erably implemented as a closed control loop which is realized using a PID (Proportional plus Integral plus Derivative) control mode. A proportional control system operates by first determining the actual value of the quantity to be controlled and the desired value, i.e. set-point, and then applying a correction proportional to this difference. The microcontroller 38 controls the amount of ozone gas 03 being generated by regulating and monitoring the amount of oxygen 24 entering the chamber 11 and/or the voltage applied to the grids 28. The addition of the integral and derivative terms in the transfer function improves the performance of the control loop. For the ozone control loop, the derivative term is selected to compensate for the sequential lag of the output from electrodes 28 and the generation of ozone gas 03 in the chamber 11. The implementation of the control loop in software will be within the understanding of those skilled in the art and further explanation is not needed.
The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the presently discussed embodiments are considered to be illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, and all changes which come within the mP~ning and range of equivalency of the claims are therefore intended to be embraced therein.
This invention relates to apparatus for generating ozone gas, and more particularly to an apparatus with an in-line sensor which is suitable ~or applications in which the concentration o~ ozone gas needs to be carefully controlled.
In the art, ozone generators are well-known.
United States Patent 5 052.382, which issued to Wainwright on October 1, 1991, describes an apparatus for the controlled generation and ~mi ni stration of ozone gas. The apparatus disclosed by Wainwright comprises a generator for generating the ozone, a monitor ~or monitoriny the ozone, a dosage device for providing the amount of ozone and a computer for controlling operation o~ the apparatus.
While Wainwright discloses an ozone generating apparatus suitable ~or medical application, there are aspects which a~ect the per~ormance and accuracy of the device. The monitor or sensor taught by Wainwright comprises an ultra violet light source and a strobed detector. The detector is strobed by a zeon light source, but according to Wainwright, it may be strobed by another light source. As will be understood by those skilled in the art, this arrangement comprises an intrusive measurement technique. According to this techni~ue, the ozone and oxygen gas stream is exposed to ultra violet light. The W light interacts with the ozone and the amount of W light which is measured by the sensor will be dependent on the concentration o~ the ozone gas. Because there is an interaction between the W light and the ozone gas, the W light a~ects the concentration o~ the ozone gas which is produced by the generator. There~ore, the ozone generator taught by Wainwright is not well-suited ~or applications where the ozone concentration must be very accurately controlled, nor is the Wainwright device suited ~or an application where the ozone sensor is in-line with the treatment.
CA 0222~483 1997-12-22 It is object of the present invention to provide an apparatus for generating ozone gas having an electronic circuit capable of carefully controlling the amount of ozone being generated. It is another object o~
the present invention to provide an apparatus for generating ozone gas having a non-intrusive sensor for sensing the concentration of the ozone gas being produced.
It is another object of the present invention to provide an ozone sensor which can be located "in-line" with the treatment path.
According to one aspect of the present invention, there is provided an apparatus for generating ozone from an oxygen supply, said apparatus comprising: (a) an enclosure having an inlet for receiving said oxygen supply and an outlet for releasing said ozone and said oxygen; (b) a plurality of grids mounted inside said enclosure and said grids being separated by plates; (c) energizer means for energizing said grids, said energizer means having a control input for receiving a control signal and an input port for connecting to a power source; and (d) said energizer means including generator means for generating a high voltage output coupled to said grids for energizing said grids and producing an electric field, and said generator means being responsive to said control signal.
According to another aspect of the present invention, there is provided a bridge network and control circuit for linearly controlling an AC signal. The apparatus for linearly controlling an AC signal comprising (a) a bridge network having an input port for receiving an AC signal, and said bridge network including a switching control input and a bridge output port; (b) a control circuit having an input for receiving a control signal and an output coupled to the switching control input o~ said bridge network, and said control circuit having means for CA 0222~483 l997-l2-22 generating a switching control signal at said output for switching said bridge network and producing a controlled power signal at said bridge output port; and (c) a trans~ormer having an output port and an input port coupled to the output port of said bridge output port and means responsive to said controlled power signal for producing a high voltage output signal at said output port.
Reference will now be made to the drawings which illustrate, by way of example, a preferred embodiment of the present invention, FIGURE 1 is a diagrammatic illustration of an apparatus according to a speci~ic embodiment of the present invention; and FIGURE 2 is a schematic diagram of the control circuitry for the embodiment shown in Fig. 1.
Reference is first made to Figure 1 which shows an ozone generator 1 according to the present invention. The ozone generator 1 is suitable for the generation of carefully measured amounts of ozone gas and has particular though by no means exclusive application to medical applications. The apparatus and particularly the control circuit have wider applicability, such as applications where high voltage needs to be carefully controlled.
As shown in Figure 1, the ozone generator 1 comprises a housing or enclosure 10. The housing 10 is formed from PTFE material co~monly known as Te~on~, preferably medical grade. Te~on is preferred because it is an inert substance which is impervious to ozone and preferably the housing 10 is milled from a solid block of CA 0222~483 1997-12-22 Teflon~. The housing 10 can also be made from Kynar~
material available from the Pennwalt Corporation and other compositions such as CPCVC or silicon which are of medical grade. As shown, the housing 10 includes a lid 12 which is also made from medical grade Te~on~. The lid 12 is attached to the enclosure 10 by secure fasteners 14, for example, precision screws. The enclosure 10 includes an inlet port 16 and an outlet port 18. The inlet 16 provides the input for oxygen gas 24 and is coupled to an oxygen supply tank 20 through a gas flow control valve 22. The gas flow control valve 22 is coupled to control circuit 32 through a stepper motor 23 or other appropriate actuator.
A ~ow meter 25 is also included which provides the rate of flow of the oxygen gas 24 into the enclosure 10. The outlet port 18 provides an output for gas 26 comprising oxygen and ozone produced by the generator 1. As shown in Figure 1, a temperature sensor 19 can also be provided to sense the temperature inside the enclosure 10. The control circuit 32 uses the temperature readings to control the production of ozone.
The ozone generator 1 includes a series of grids or electrodes 28a,28b,28c which are mounted in a spaced relationship inside the chamber 11 formed by the enclosure 10 as shown in Figure 1. Preferably, the grids or electrodes 28a,28b,28c are made from high-grade stainless steel. A pair of mica sheets 30a,30b separate the grids 28. The ozone generator 1 has a control circuit and power supply module 32. The control circuit 32 is powered by conventional AC power 34, i.e. mains supply.
The control circuit 32 has a high voltage output 36 which connects to the grids 28a,28b,28c. The control circuit 32 biases the grids 28a,28b,28c to a high voltage level to produce an electric field which causes the formation of ozone gas 03 in the stream of oxygen 24 which enters the chamber 11 through the inlet port 16 and passes over the electrodes 28. The circuit 32 uses the gas flow control CA 0222~483 1997-12-22 valve 22 to regulate the amount of oxygen 24 entering the chamber 11. The ozone generator 1 can also include a relay 33 (Figure 2) as a safety feature which is activated by the control circuit 32 to enable the high voltage feed to the electrodes 28.
Re~erence is next made to Figure 2, which shows the control circuit 32 in more detail. The control circuit 32 preferably comprises a microprocessor-based circuit suitably programmed for operating the gas ~ow control valve 22 and the ozonizer 1.
As shown in Figure 2, the control circuit 32 comprises a microcontroller 38, a high voltage drive circuit 40, a high voltage trans~ormer 42, and a sensing circuit 44. The high voltage drive circuit 40 is connected to the transformer 42 which produces the high voltage output for biasing the grids 28. The sensing circuit 44 is coupled to the output of the transformer 42 and is used by the microcontroller 38 to determine the amount of ozone gas 03 being generated as will be described below.
The high voltage drive 40 has an input 46 connected to an output port of the microcontroller 38 for receiving a control signal 48. The control signal 48 comprises a pulse train which is generated by the microcontroller 38. The high voltage drive circuit 40 as shown in Figure 2 comprises a bridge network 50 and a bridge control circuit 52. The bridge network 50 comprises four diodes 50a,50b,50c,50d connected in a bridge configuration. As shown in Figure 2, the bridge network 50 couples the "live~ AC voltage 34 to the primary winding of the high voltage transformer 42. The current ~owing in the primary winding of the transformer 42 is controlled by the circuit 52 which is coupled to the other port 54 of the bridge 50. The current which ~ows in the bridge 50 and primary winding induces a voltage in the secondary winding CA 0222~483 1997-12-22 of the high voltage transformer 42 which biases the grids or electrodes 28 ( Figure 1).
The function of the bridge network 5 0 and the bridge control circuit 52 is to regulate the current flowing in the primary winding and thereby the high voltage induced in the secondary winding of the transformer 42 and applied to the grids 28. By regulating the high voltage applied to the grids 28, the amount of ozone gas Q~ which is generated can be carefully controlled. As will be described, the bridge control circuit 52 together with the control signal 48 regulate both the shape and level of the high voltage signal which biases the electrodes 28, thereby providing accurate control for the production of ozone.
The bridge control circuit 52 comprises an input transistor 56, an isolation transformer 58 and an output transistor 60. The isolation transformer 58 is needed because the bridge network 50 iS "floating" at 110 VAC (or 220 VAC). The base of the transistor 56 forms the input 46 for receiving the control signal 48 from the microcontroller 38. The control signal 48 comprises a pulse train generated by the microcontroller 38. According to the invention, either the pulse width or the frequency of the control signal 48 can be varied to control the current flowing through the bridge 5 0 and the primary winding of the transformer 42. The pulse width (or frequency) of the control signal 48 iS selected to produce a target ozone level and the actual amount of ozone being produced is determined through the sensing circuit 44. The collector of the transistor 56 iS connected to the primary winding of the isolation transformer 58 so that the pulse train produced by the signal 48 is induced in the secondary winding of the transformer 58. The secondary winding of the transformer 58 is connected to a diode 62 and a capacitor 64. The diode 62 rectifies the output from the secondary winding of the isolation transformer 58 and CA 0222~483 1997-12-22 charges the capacitor 64 to yenerate a DC voltage. The base o~ the output transistor 60 is connected to the capacitor 64 through a resistive divider formed from resistors 66,68. Another resistor 70 is connected to the emitter of the transistor 60 to limit the current ~owing through the transistor 60. The values of the resistors are chosen to operate the output transistor 60 in the linear or active region. By operating the output transistor 60 in the active region, a sinusoidal output ~rom the bridge 50 is produced thereby allowing precision linear control of the voltage output from the secondary winding of the trans~ormer 42 which is applied to the grids or electrodes 28.
The sensing circuit 44 is coupled to the secondary winding o~ the high voltage transformer 42 and provides the microcontroller 38 with data for determining the amount o~ ozone gas 03 being produced. The microcontroller 38 uses this inform.ation to control the operation of the ozone generator 1. The microcontroller 38 can be programmed to respond to comm~n~ from another computer (not shown) or the microcontroller 38 can include an input panel (not shown) for m~nll~lly setting the desired ozone gas level.
Figure 2 also shows the sensing circuit 44 in more detail. The sensing circuit 44 produces an output signal 72 corresponding to the discharges occurring in the chamber 11 which are also related to the production o~
ozone gas 03 ~rom the oxygen 24. The microcontroller 38 uses the output 72 from the sensing circuit 44 to calculate the amount of ozone gas 03 being generated by the ozonizer 1. Each time there is a discharge between the electrodes 28 mounted in the cha-mber 11 (Figure 1), a pulse is produced in the winding o~ the high voltage transformer 42.
A pickup coil 74 is electromagnetically coupled to the winding of high voltage transformer 42 and pulses due to CA 0222~483 1997-12-22 discharges will induce a current in the pickup coil 74.
The sensing circuit 44 detects these pulses and produces the output 72 for the microcontroller 38.
Referring to Figure 2, the sensing circuit 44 comprises a diode 76, a capacitor 78, a resistor 80 and an operational amplifier 82. The operation amplifier 82 (op amp) is configured as a voltage follower or unity gain buffer and functions as an isolating circuit. The capacitor 78 is charged through the diode 76 by the induced voltage in the pickup coil 74 and provides an input voltage for the op amp 82. The op amp 82 produces a corresponding output pulse 72 which is inputted by the microcontroller 38. The microcontroller 38 includes program code which determines the amount of ozone 03 produced by the discharge by calculating the area of the pulse. The readings from the flow rate meter 25 are factored into the calculation.
Preferably the temperature inside the enclosure 11 is also taken into account, i.e. as the temperature inside the enclosure 11 rises the voltage to the grids 28 needs to be increased. If the stream of oxygen 24 comprises medical grade oxygen then there is a direct correspondence between the input energy and the amount of ozone 03 generated. If the oxygen 24 does not comprise medical grade oxygen, i.e.
pure oxygen, then a correction factor is introduced into the calculation.
A significant advantage of the sensing circuit 44 and microcontroller 38 arrangement according to the present invention is the capability to perform an ozone measurement ~lin-linel~. Because the measurement can be taken in-line, the problem of the ozone gas 03 being contaminated or altered by the measurement technique is eliminated.
CA 0222~483 1997-12-22 g The microcontroller 38 can be implemented using the commercially available PIC16C71 microcontroller available from Microchip Technologies Inc. which has been suitably programmed to perform the processing steps according to the present method. The PIC16C71 controller is a single chip device comprising a microprocessor and "on-chip" program memory, data memory, input/output ports, timers and other on-chip resources.
The control loop for controlling the operation of the ozone generator 1 is pre~erably implemented as a closed control loop which is realized using a PID (Proportional plus Integral plus Derivative) control mode. A proportional control system operates by first determining the actual value of the quantity to be controlled and the desired value, i.e. set-point, and then applying a correction proportional to this difference. The microcontroller 38 controls the amount of ozone gas 03 being generated by regulating and monitoring the amount of oxygen 24 entering the chamber 11 and/or the voltage applied to the grids 28. The addition of the integral and derivative terms in the transfer function improves the performance of the control loop. For the ozone control loop, the derivative term is selected to compensate for the sequential lag of the output from electrodes 28 and the generation of ozone gas 03 in the chamber 11. The implementation of the control loop in software will be within the understanding of those skilled in the art and further explanation is not needed.
The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the presently discussed embodiments are considered to be illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, and all changes which come within the mP~ning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (19)
1. An apparatus for generating ozone from oxygen provided from an oxygen supply at a known concentration and measurable flow rate, said apparatus comprising:
(a) an enclosure having an inlet for receiving oxygen from said oxygen supply and an outlet for releasing ozone and oxygen;
(b) a plurality of electrodes mounted inside said enclosure and said electrodes being separated by a dielectric;
(c) energizer means for energizing said electrodes, said energizer means having a control input for receiving a control signal and an input port for connecting to a power source;
(d) said energizer means including generator means responsive to said control signal for generating a high voltage at an output coupled to said electrodes for energizing said electrodes and producing an electric field for forming ozone from said oxygen; and (e) means for determining the amount of ozone being produced comprising sensor means coupled to the high voltage output of said generator means for sensing discharge current produced by interaction of said oxygen and said electric field in formation of said ozone, and means for calculating the amount of ozone from the energy in said discharge current and the concentration and flow rate of the oxygen from said oxygen supply.
(a) an enclosure having an inlet for receiving oxygen from said oxygen supply and an outlet for releasing ozone and oxygen;
(b) a plurality of electrodes mounted inside said enclosure and said electrodes being separated by a dielectric;
(c) energizer means for energizing said electrodes, said energizer means having a control input for receiving a control signal and an input port for connecting to a power source;
(d) said energizer means including generator means responsive to said control signal for generating a high voltage at an output coupled to said electrodes for energizing said electrodes and producing an electric field for forming ozone from said oxygen; and (e) means for determining the amount of ozone being produced comprising sensor means coupled to the high voltage output of said generator means for sensing discharge current produced by interaction of said oxygen and said electric field in formation of said ozone, and means for calculating the amount of ozone from the energy in said discharge current and the concentration and flow rate of the oxygen from said oxygen supply.
2. The apparatus as claimed in claim 1, further including a temperature sensor for producing a temperature reading signal indicative of the temperature in said enclosure and said means for calculating being responsive to said temperature reading.
3. The apparatus as claimed in claim 1, wherein said generator means for generating a high voltage output comprises means for producing a controlled AC output responsive to said control signal.
4. The apparatus as claimed in claim 1, wherein said enclosure is formed from medical grade teflon material.
5. The apparatus as claimed in claim 1 or 3, wherein said control signal comprises a pulse width modulated signal.
6. An apparatus for linearly controlling an AC signal for an apparatus for generating ozone, said apparatus comprising:
(a) a bridge network having an input port for receiving an AC signal, and said bridge network including a switching control input and a bridge output port;
(b) a control circuit having an input for receiving a control signal and an output coupled to the switching control input of said bridge network, and said control circuit having means responsive to said control signal for generating a switching control signal at said output for switching said bridge network and producing a controlled power signal at said bridge output port; and (c) a transformer having an output port and an input port coupled to said bridge output port and means responsive to said controlled power signal for producing a high voltage output signal at said output port.
(a) a bridge network having an input port for receiving an AC signal, and said bridge network including a switching control input and a bridge output port;
(b) a control circuit having an input for receiving a control signal and an output coupled to the switching control input of said bridge network, and said control circuit having means responsive to said control signal for generating a switching control signal at said output for switching said bridge network and producing a controlled power signal at said bridge output port; and (c) a transformer having an output port and an input port coupled to said bridge output port and means responsive to said controlled power signal for producing a high voltage output signal at said output port.
7. The apparatus as claimed in claim 6, wherein said means for generating a switching control signal comprises a transistor.
8. The apparatus as claimed in claim 6 or 7, wherein said control signal comprises a pulse width modulated signal.
9. The apparatus as claimed in claim 6 or 7, wherein said control signal comprises a square wave having a variable frequency.
10. The apparatus as claimed in claim 3, wherein said means for producing a controlled AC output signal responsive to said control signal comprises a transformer having an input port and an output port and a bridge network having an input for connecting to said power source and an output coupled to the input port of said transformer and a bridge control input, and said means for producing a controlled AC output including a switching circuit coupled to the bridge control input for switching said bridge network in response to said control signal to produce said high voltage output at the output port of said transformer.
11. A sensor for determining the amount of ozone being produced by an ozone generator comprising an enclosure with an inlet for receiving oxygen from an oxygen supply at a known concentration and measurable flow rate and an outlet for releasing ozone and oxygen, and the generator including a plurality of electrodes mounted inside the enclosure and being separated by a dielectric and a high voltage generator having a control input for receiving a control signal, an input port for connecting to a power source and an output coupled to the electrodes for energizing the electrodes in response to the control signal and producing an electric field for forming ozone from the oxygen, said sensor comprising:
(a) sensing means coupled to the output of the high voltage generator for sensing a discharge current produced by the interaction of the oxygen with the electric field in the formation of ozone;
(b) means for determining the amount of ozone being produced by the ozone generator from said discharge current;
(c) said means for determining the amount of ozone being responsive to the concentration and flow rate of the oxygen being supplied by the oxygen supply.
(a) sensing means coupled to the output of the high voltage generator for sensing a discharge current produced by the interaction of the oxygen with the electric field in the formation of ozone;
(b) means for determining the amount of ozone being produced by the ozone generator from said discharge current;
(c) said means for determining the amount of ozone being responsive to the concentration and flow rate of the oxygen being supplied by the oxygen supply.
12. The sensor as claimed in claim 11, wherein said sensing means comprises a coil electromagnetically coupled to the output of the high voltage generator.
13. The sensor as claimed in claim 12, wherein said means for determining the amount of ozone being produced comprises a programmed microcontroller coupled to receive a signal corresponding to said discharge current and data corresponding to the concentration and flow rate of the oxygen.
14. The sensor as claimed in claim 13, wherein said sensing means includes an amplifier coupled to the output of said coil, and having means for generating said signal for said microcontroller.
15. The sensor as claimed in claim 14, wherein said ozone generator further includes a temperature sensor for producing a temperature reading signal indicative of the temperature in said enclosure and said microcontroller having an input for receiving said temperature reading signal.
16. The sensor as claimed in claim 15, wherein said ozone generator further includes a flow rate meter coupled to the oxygen supply and having means for generating a flow rate reading for said microcontroller.
17. The sensor as claimed in claim 16, wherein said control signal comprises a pulse width modulated signal.
18. A sensor for determining the amount of ozone being produced by an ozone generator comprising an enclosure with an inlet for receiving oxygen from an oxygen supply at a known concentration and measurable flow rate and an outlet for releasing ozone and oxygen, and the generator including a plurality of electrodes mounted inside the enclosure and being separated by a dielectric and a high voltage generator having a control input for receiving a control signal, an input port for connecting to a power source and an output coupled to the electrodes for energizing the electrodes in response to the control signal and producing an electric field for forming ozone from the oxygen, said sensor comprising:
(a) sensing means coupled to the output of the high voltage generator for sensing a discharge current produced by the interaction of the oxygen with the electric field in the formation of ozone, said sensing means comprising a coil electromagnetically coupled to the output of the high voltage generator and an amplifier coupled to the output of said coil for generating a signal corresponding to said discharge current; and (b) a microcontroller coupled to receive said signal and having means for reading the concentration and flow rate levels of the oxygen being supplied by the oxygen supply and means for determining the amount of ozone being produced by the ozone generator.
(a) sensing means coupled to the output of the high voltage generator for sensing a discharge current produced by the interaction of the oxygen with the electric field in the formation of ozone, said sensing means comprising a coil electromagnetically coupled to the output of the high voltage generator and an amplifier coupled to the output of said coil for generating a signal corresponding to said discharge current; and (b) a microcontroller coupled to receive said signal and having means for reading the concentration and flow rate levels of the oxygen being supplied by the oxygen supply and means for determining the amount of ozone being produced by the ozone generator.
19. An apparatus for generating ozone from an oxygen supply, said apparatus comprising:
(a) an enclosure having an inlet for receiving said oxygen supply and an outlet for releasing ozone and oxygen;
(b) a plurality of electrodes mounted inside said enclosure and said electrodes being separated by a dielectric;
(c) energizer means for energizing said electrodes, said energizer means having a control input for receiving a control signal and an input port for connecting to a power source;
(d) said energizer means including generator means for generating a controllable AC voltage at an output in response to said control signal, and said output being coupled to said electrodes for energizing said electrodes and producing an electric field for forming ozone from said oxygen; and (e) said generator means for generating a controllable AC voltage including a transformer having an input port and an output port and a bridge network having in input for connecting to said power source and an output coupled to the input port of said transformer and a bridge control input, and said generator means including a switching circuit coupled to the bridge control input for switching said bridge network in response to said control signal to produce said high voltage output at the output port of said transformer.
The claims in the subject application have been amended to clarify the language and better distinguish the invention over the prior art.
(a) an enclosure having an inlet for receiving said oxygen supply and an outlet for releasing ozone and oxygen;
(b) a plurality of electrodes mounted inside said enclosure and said electrodes being separated by a dielectric;
(c) energizer means for energizing said electrodes, said energizer means having a control input for receiving a control signal and an input port for connecting to a power source;
(d) said energizer means including generator means for generating a controllable AC voltage at an output in response to said control signal, and said output being coupled to said electrodes for energizing said electrodes and producing an electric field for forming ozone from said oxygen; and (e) said generator means for generating a controllable AC voltage including a transformer having an input port and an output port and a bridge network having in input for connecting to said power source and an output coupled to the input port of said transformer and a bridge control input, and said generator means including a switching circuit coupled to the bridge control input for switching said bridge network in response to said control signal to produce said high voltage output at the output port of said transformer.
The claims in the subject application have been amended to clarify the language and better distinguish the invention over the prior art.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002225483A CA2225483A1 (en) | 1995-05-26 | 1995-05-26 | Ozone generator with in-line sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002225483A CA2225483A1 (en) | 1995-05-26 | 1995-05-26 | Ozone generator with in-line sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2225483A1 true CA2225483A1 (en) | 1996-11-28 |
Family
ID=4161933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002225483A Abandoned CA2225483A1 (en) | 1995-05-26 | 1995-05-26 | Ozone generator with in-line sensor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2225483A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6280633B1 (en) | 1999-12-01 | 2001-08-28 | Fantom Technologies Inc. | Ozone sensor and method for use of same in water purification system |
| EP3683188A1 (en) * | 2019-01-16 | 2020-07-22 | OP-Hygiene IP GmbH | Ozone generator with sensor |
-
1995
- 1995-05-26 CA CA002225483A patent/CA2225483A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6280633B1 (en) | 1999-12-01 | 2001-08-28 | Fantom Technologies Inc. | Ozone sensor and method for use of same in water purification system |
| EP3683188A1 (en) * | 2019-01-16 | 2020-07-22 | OP-Hygiene IP GmbH | Ozone generator with sensor |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |