WO2001071442A1

WO2001071442A1 - Apparatus and method for dispensing a predetermined amount of fluid

Info

Publication number: WO2001071442A1
Application number: PCT/US2001/007041
Authority: WO
Inventors: Ian Houston; Keith Bunce; Salvador Garcia
Original assignee: Fmc Corporation
Priority date: 2000-03-16
Filing date: 2001-03-06
Publication date: 2001-09-27
Also published as: AR027670A1; AU2001243430A1

Abstract

An apparatus and method for dispensing a predetermined amount of fluid, such as an enzyme solution, is disclosed. A supply line (26) and discharge line (38) are operatively connected to the lower discharge end of a fluid injection tube (20). An intake sensor (74) and discharge sensor (76) positioned below the intake sensor determine when fluid has reached a desired level within the injection tube (20). The fluid is supplied from a fluid supply line connected to a container of fluid (14). The discharge sensor (76) determines when a predetermined amount of fluid has been discharged from the fluid injection tube (20) into a discharge line operatively connected to the lower discharge end of the injection tube (20). A programmable logic controller (70) controls intake (32), discharge (36) and air valves (44) for controlling the filling and discharging of fluid to and from the fluid injection tube (20).

Description

APPARATUS AND METHOD FOR DISPENSING A PREDETERMINED AMOUNT OF FLUID

Field of the Invention

This invention relates to the field .of dispensing a metered amount of fluids, such as concentrated or diluted enzymes, and more- particularly, this invention relates to the field of dispensing fluids from a metered fluid injection tube that is supplied by a container of fluid.

Background of the Invention Minute amounts of concentrated or diluted enzyme solutions are used in citrus processing to speed the chemical reaction for pulp washing and other citrus processes. The citrus juice has pectins and other components. The enzymes are used to break down the pectins and to form a lower viscosity citrus product to enhance processing. The enzymes also aid in the processing of the citrus juice because evaporation rates can be controlled with the use of enzymes.

In one prior art citrus processing technique, a concentrated enzyme is diluted to about a 1:10 ratio. This diluted enzyme is then pumped via a metering pump into a citrus liquid in various stages of processing. However, a metering pump has not been found to be an adequate technique for precisely metering minute amounts of enzyme that could be discharged into the citrus product. Too much enzyme applied during citrus processing would lower the viscosity beyond what is acceptable. Also, the metering pumps often cannot be set at a low discharge level for metering a minute amount of enzyme flow from the pump discharge port . Most metering pumps should be continually pumped because the enzymes tend to form crystals that lock the metering pump. Additionally, the metering pumps cannot be readily programmed to meter enzymes on a continual basis, and cannot be operated to meter the minute enzyme amounts that are typically required for citrus production.

Summary of the Invention

It is therefore an object of the present invention to provide an apparatus and method for dispensing a predetermined amount of enzymes where the apparatus can be programmed for a sequence of metering events and/or a predetermined amount of enzyme dispensing.

It is still another object of the present invention to provide an apparatus and method for dispensing a predetermined amount of fluid in a precise, controlled manner in a simple fashion without metering pumps.

In accordance with the present invention, an apparatus for dispensing a predetermined amount of fluid includes a container of fluid and a fluid injection tube having a lower discharge end and upper end. A fluid supply line and fluid discharge line are operatively connected to the lower discharge end of the fluid injection tube. The fluid supply line is connected to the container of fluid and positioned for allowing fluid to flow preferably by gravity from the container of fluid into the fluid injection tube. An air valve in the form of a preferred three-way air valve is operatively connected to the upper end of the fluid injection tube. The three-way air valve has a pressure line and vent in the form of a vent line connected thereto. A fluid intake valve is positioned within the fluid supply line, and a fluid outlet valve is positioned within a fluid discharge line. Fluid flows into the fluid supply line and into the fluid injection tube when the fluid intake valve is open, the fluid outlet valve is closed, and the three-way air valve is switched into the vent line. Fluid is discharged from the fluid injection tube when the fluid intake valve is closed, the fluid outlet valve is open, and the three- way air valve is switched into the pressure line.

An intake sensor senses when the fluid has reached a desired level within the fluid injection tube. A discharge sensor is positioned below the intake sensor and senses when a predetermined amount of fluid has been discharged from the fluid injection tube . A controller is operatively connected to the intake and discharge sensors for receiving signals from the sensors, and connected to the intake, discharge and three-way valves for controlling the filling and discharging of fluid to and from the fluid injection tube.

In still another aspect of the present invention, the controller preferably comprises a programmable logic controller that is programmed to receive signals on fluid level from the sensors, and open and close the valves to dispense a predetermined amount of fluid. The distance between the discharge sensor and the intake sensor can be adjusted relative to each other for changing the quantity of fluid that is discharged from the injection tube. Different injection tubes having different predetermined bore sizes and can also be mounted for changing the quantity of fluid that is injected from the fluid discharge tube. In yet another aspect of the present invention, a T-connection can be positioned at the lower discharge end of the fluid injection tube. The fluid supply line and fluid discharge line are connected to the T-connection. The intake and discharge valves comprise solenoid valves and the three-way air valve comprises a three-way solenoid air valve in still another aspect of the present invention. The discharge sensor and intake sensor both comprise photoelectric sensors in yet another aspect of the present invention. A pressure source is connected to the pressure line for supplying air under pressure into the fluid injection tube when the three-way air valve is switched into the pressure line.

Brief Description of the Drawings

Other objects, features and advantages of the present invention will become apparent from the detailed description of the invention which follows, when considered in light of the accompanying drawings in which:

FIG. 1 is a block, diagrammatic representation of one embodiment of the apparatus of the present invention for dispensing fluids, such as an enzyme solution.

FIG. 2 is an enlarged, side elevation view of a portion of the fluid injection tube showing the intake and discharge photoelectric sensors and a mounting mechanism for changing the distance between the intake and discharge photoelectric sensors .

FIG. 3 is a flow chart illustrating a basic method of the present invention.

Detailed Description of the Preferred Embodiments

The present invention is advantageous because it now provides an apparatus and method for dispensing a minute, predetermined amount of fluid in a metered fashion, such as for a concentrated or diluted enzyme solution, without the necessity of having metering pumps or other complicated apparatus to supply fluid into a fluid injection tube. The apparatus also ca be programmed such that the metering and fluid dispensing functions can be performed automatically during the processing of citrus juice or other products which receive the metered dosages of fluid.

As shown in FIG. 1, the apparatus 10 includes an enclosure 12, which contains major components of the apparatus . The enclosure 12 is typically an environmentally protected and sealed housing that is protected against the harsh environment and conditions associated with citrus juice processing. The enclosure protects the various solenoid valves, switches, programmable logic controller, and other electronic components, as explained in greater detail below. A fluid vessel 14 is mounted by a bracket 14a on the outside of the enclosure, and in one aspect of the present invention, contains a concentrated enzyme solution. In another aspect of the present invention, the enzyme solution could be diluted, such as in a 1:10 ratio. The fluid vessel 14 is typically formed from

Teflon or other similar material that is non-reactive to enzymes and other similar materials and' also will not corrode. The vessel 14 can be about one liter in capacity, but its capacity can vary as known to those skilled in the art. The vessel 14 is positioned at a vertical height to create a pressure head downward, as will be explained below.

A fluid injection tube 20, such as formed from glass or other transparent or partially transparent material, is mounted vertically on a support plate 21 within the enclosure 12 by mounting devices, such as clamps or brackets 20a. The fluid injection tube 20 has a predetermined bore size, such that the amount or quantity of fluid contained in a respective length of fluid injection tube would be known, based upon the predetermined bore size and the height of the fluid contained within the fluid discharge tube. FIG. 2 illustrates that the fluid discharge tube has metering indicia 22 printed on the tube such that the amount of fluid contained within the fluid injection tube 20 could be gauged visually by an operator.

A fluid fitting 24 is positioned at the lower end of the fluid vessel 14 and connects to a fluid supply line 25, which in turn, connects into a fluid fitting 28 located on the lower portion of the enclosure. The fluid vessel 14 is vented at the top through a vented cap to allow air venting and create the pressure head to allow fluid to flow from the fluid vessel, through the fluid supply line 26 into a first intake solenoid valve 32, which is connected into a

T-fitting 34. The intake solenoid valve 32 is mounted on the support plate 21 within the enclosure by brackets 32a and forms a fluid connection between the intake solenoid valve 32, the lower end of the fluid injection tube 20 via the T-fitting 34 and an outlet solenoid valve 36 that is connected to the other end of the T-fitting via a respective fluid discharge line 38.

As illustrated, the upper end of the fluid discharge tube 20 includes an air fitting 40 and an air line 42 that connects into an air valve, such as a three-way solenoid air valve 44, having a first port 46 connected to the air line, a second port 48 connected to a vent such as the illustrated vent line 50 that extends out through the enclosure via a vent fitting 52, and a third port 54 that connects into an air pressure line 56 and through the enclosure 12 via a pressure fitting 58, which connects into a pressure source 60, such as a source of pressurized air. The three-way solenoid air valve 44 is mounted on the support plate 21 via brackets or other means 44a.

A precision air regulator 62 is mounted on the support plate and connected into the pressure line 56 to regulate the amount of air pressure supplied by the pressure source 60 through the air pressure line 5β via the three-way solenoid air valve 44 and into the fluid injection tube 20. In one aspect of the invention, the precision air regulator 62 can be manually adjusted through a control knob 64 extending beyond the enclosure 12 and visually monitored via a pressure gauge 66 . In another aspect of the present invention, the air regulator could be controlled via a programmable logic controller 70 mounted in the enclosure, as will be explained below.

.The programmable logic controller 70 is also connected to the three-way solenoid air valve 44 and the intake and outlet solenoid fluid valves 32,36 to control the opening and closing of the respective intake and outlet solenoid fluid valves 32, 36 and control the switching of the three-way solenoid air valve 44 between the vent line 50 and air pressure line

56. As known to those skilled in the art, the programmable logic controller 70 includes the standard logic relays, such as could be formed in a ladder configuration, or any other logical circuit configuration known to those skilled in the art. The type of input and output modules used in the programmable logic controller can be selected by those skilled in the art, as well as t.he type of processor used in the programmable logic controller. A programming computer 72, such as a personal computer, can be used for programming the programmable logic controller 70 to operate the system.

In accordance with the present invention, an intake sensor 74, in the form of a photoelectric sensor, is positioned for sensing when fluid has reached a desired level within the fluid injection tube. A discharge sensor 76, in the form of another photoelectric sensor, is positioned below the intake sensor 74 and senses when a predetermined amount or quantity of fluid has been discharged from the fluid injection tube 20. The sensors are positioned, such as shown in detail of FIG. 2, within respective sensor mounting blocks 80,82. The sensor mounting blocks 80,82 receive the fluid intake tube and the mounting blocks are movable relative to the fluid intake tube.

In one aspect of the present invention as shown in FIG. 2, it is possible to have a powered and threaded control shaft 84 that extends through the mounting blocks 80,82. The shaft end is mounted on the lower positioned mounting block 82. A motor 86 is connected to the programmable logic controller 70 and is operative to rotate the control shaft 84 such that upon rotation, the upper mounting block 80 is moved linearly relative to the lower mounting block 82 holding the discharge sensor 76. Thus, the relative distance between the intake and discharge sensors 74,76 can be adjusted for changing the amount of fluid that is metered and discharged from the fluid intake tube, as will be explained below.

The intake and discharge photoelectric sensors 74,76 are both connected via respective amplifier circuit 88 to the programmable logic controller 70, such that signals produced from the photoelectric sensors are passed into the programmable logic controller %0 input module and then converted into logic signals that are processed by the processor of programmable logic controller to produce outputs for controlling the respective valves. The fluid discharge line 38 extends from the discharge solenoid fluid valve through the fitting 40 on the enclosure 12 and into a metering fluid nozzle 90, through which the enzyme solution or other fluid is ejected into a citrus juice or other fluid.

Referring now to FIG. 3, there is illustrated a flow chart showing an example of a basic method for practicing the invention. The flow chart is only one example of numerous embodiments. In operation_., at the start (block 100) , the fluid injection tube would be empty. The intake solenoid fluid valve is initially opened while the outlet solenoid fluid valve is closed. The three-way solenoid air valve has the second port connected into the vent line, such that enzyme or other fluid is discharged from the fluid vessel 14 through the fluid supply line 26, through the intake solenoid fluid valve 32 into the lower portion of the fluid injection tube 20 via the T-fitting 34 (block 102) . When the fluid level meniscus reaches the intake photoelectric sensor 74, a signal is generated to the programmable logic controller (block 104) , which then processes the signal and sends another signal to the intake solenoid fluid valve to shut off fluid flow from the fluid vessel 14 (block 106) . The programmable logic controller 70 then signals the three-way solenoid air valve to switch into the third port 54 to allow air pressure from the pressure source 60 to be applied through the precision air regulator 62 into the fluid injection tube 20 (block 108) . The programmable logic controller 70 then signals the outlet solenoid fluid valve to open (block 110) and the fluid is forced by pressure through the T-fitting 34, and through the outlet solenoid valve through the nozzle. When the fluid meniscus reaches the lower positioned discharge photoelectric sensor 76, a signal is generated back to the programmable logic controller 70 ' (block 112) which then generates a signal to close the discharge solenoid fluid valve 76 and stop the fluid flow from the nozzle

(block 114) . The three-way solenoid air valve is then switched from the pressure line into the vent line and the cycle repeats, with the intake solenoid fluid valve 32 being opened by the programmable logic controller 70 to allow fluid to flow from the fluid vessel 14 back into the fluid injection tube 20 until the intake photoelectric sensor 74 senses the meniscus. The cycle can repeat as many times as desired.

It is possible to operate the apparatus 10 intermittently or continuously depending on the requirements of the citrus processing or other fluid processing. For example, with 200 gallons of citrus processing, it may be possible to inject fluid three times from the fluid injection tube. As an example only of an amount of fluid that can be used for citrus processing, only ten parts per million of enzyme are required for a liter, and thus, as an example, about ten liters would be required for about a million liters of citrus product. Naturally, the amount of enzyme used depends on the citrus application, and can vary from about six to ten parts per million, as known to those skilled in the art. Typically, once the enzyme is diluted to the 1:10 ratio or another ratio, the enzyme can be kept for about ten hours. The concentrated enzyme is more stable. This is a benefit of using the dosing apparatus with concentrated (undiluted) enzyme.

The programmable logic controller 70 can also be programmed to compensate for temperature. If the temperature changes, then varying amounts of enzyme can be injected into the citrus fluid. The amount of enzyme injected can, of course, also be changed through changing the timing when fluid is injected. The quantity of fluid that is injected from the fluid injection tube can also be changed by varying the distance between the two sensors 74,76 as described before. It is also possible to change the fluid injection tube such that a different fluid injection tube having a different internal bore diameter can be used. FIG. 2 illustrates how the sensor mounting blocks 80,82 could receive different sizes of fluid injection tubes. The mounting blocks include spacers 80a, 82b, which could be removed to receive larger diameter fluid injection tubes. Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed, and that the modifications and embodiments are intended to be included within the scope of the dependent claims .

Claims

THAT WHICH IS CLAIMED ISs

1. An apparatus for dispensing a predetermined amount of fluid comprising: a container of fluid; a fluid injection tube having a lower discharge end and upper end; a fluid supply line and fluid, discharge line operatively connected to the lower discharge end of the fluid injection tube, said fluid supply line being connected to the container of fluid; an air valve operatively connected to the upper end of the fluid injection tube, said air valve having a pressure line and vent connected thereto; a fluid intake valve positioned within the fluid supply line and a fluid outlet valve positioned within the fluid discharge line such that fluid flows into the fluid supply line and into the fluid injection tube when the fluid intake valve is open, the fluid outlet valve is closed, and the air valve is switched into the vent, and fluid is discharged from the fluid injection tube when the fluid intake valve is closed, the fluid outlet valve is open, and the air valve is switched into the pressure line; an intake sensor for sensing when the fluid has reached a predetermined level within the fluid injection tube; a discharge sensor positioned below the intake sensor for sensing when a predetermined amount of fluid has been discharged from the injection tube; and a controller operatively connected to the intake and discharge sensors and the intake, discharge and air valves for controlling the filling and discharging of fluid to and from the fluid injection tube.

2. An apparatus according to Claim 1, wherein said controller comprises a programmable logic controller.

3. An apparatus according to Claim 1, wherein the distance between the discharge sensor and the intake sensor is adjustable in distance relative to each other for changing the quantity of fluid that is discharged from the fluid injection tube.

4. An apparatus according to Claim 1, and further comprising an injection tube mounting assembly for mounting the fluid injection tube, wherein the fluid injection tube mounting assembly allows different fluid injection tubes having different predetermined bore sizes to be mounted for changing the quantity of fluid that is injected from the fluid discharge tube.

5. An apparatus according to Claim 1, and further comprising a T-connection positioned at the lower discharge end of the fluid injection tube, wherein said fluid supply line and fluid discharge line are connected to said T-connection.

6. An apparatus according to Claim 1, wherein said fluid intake and discharge valves comprise solenoid valves.

7. An apparatus according to Claim 1, wherein said air valve comprises a three-way solenoid air valve .

8. An apparatus according to Claim 1, wherein said discharge sensor and intake sensor both comprises photoelectric sensors .

9. An apparatus according to Claim 1, and further comprising a pressure source connected to said pressure line for supplying air under pressure into said fluid injection tube when the air valve is switched into the pressure line.

10. An apparatus for dispensing a predetermined amount of enzyme into a citrus solution comprising: a container of enzyme solution; an enzyme injection tube having a predetermined bore size, a lower discharge end and upper end; a supply line and discharge line operatively connected to the lower discharge end of the enzyme injection tube, said supply line being connected to the container of enzyme solution and positioned for allowing enzyme to flow by gravity into the enzyme injection tube; a three-way solenoid air valve operatively connected to the' upper end of the enzyme injection tube, said three-way solenoid air valve having a pressure line and vent connected thereto; a source of pressure connected to said pressure 1ine; an intake solenoid valve positioned within the supply line and an outlet solenoid valve positioned within the discharge line such that enzyme solution flows into the supply line from the container of enzyme solution and into the enzyme injection tube when the intake solenoid valve is open, the outlet solenoid valve is closed, and the three-way solenoid air valve is switched into the vent, and enzyme solution is discharged from the enzyme injection tube when the intake solenoid valve is closed, the outlet solenoid valve is open, and the three-way solenoid air valve is switched into the pressure line and into the source of pressure connected thereto; an intake photoelectric sensor for sensing when the enzyme solution has reached a predetermined intake level within the enzyme injection tube; a discharge photoelectric sensor positioned below the intake photoelectric sensor for sensing when a predetermined amount of enzyme solution has been discharged from the fluid injection tube; and a programmable logic controller operatively connected to the photoelectric sensors and the intake, discharge and three-way solenoid valves for controlling the filling and discharging of enzyme solution to and from the enzyme injection tube.

11. An apparatus according to Claim 10, wherein said intake and discharge photoelectric sensors are adjustable in distance relative to each other for metering the amount of enzyme solution that is discharged form the enzyme injection tube.

12. A method for dispensing a predetermined volume of fluid comprising the steps of:

' feeding a fluid through a fluid supply line into the lower discharge end of a fluid injection tube that is connected at its upper end to an air valve having a vent and pressure line connected thereto so as to allow fluid to fill the fluid injection tube as the air valve is switched to allow air venting through the vent ; sensing when the fluid has reached a predetermined level within the fluid injection tube; cutting off the flow of fluid within the fluid injection tube by switching a fluid intake valve that is positioned within the supply line into an off position; switching the air valve into the fluid pressure line and applying air pressure within the fluid injection tube via the pressure line; discharging the fluid through the fluid injection tube by opening a fluid outlet valve positioned within a discharge line connected to the lower end of the fluid injection tube; sensing when the fluid has reached a predetermined discharge level within the fluid injection tube; and closing the outlet valve to stop the flow of fluid from the fluid injection tube.

13. The method according to Claim 12, and further comprising the step of sensing when the fluid has reached a predetermined level within the fluid injection tube by photoelectrically sensing the level of fluid with an intake photoelectric sensor and photoelectrically sensing when the fluid has reached a predetermined discharge level by a photoelectric discharge sensor positioned below the intake photoelectric sensor.

1 . The method according to Claim 13 , and further comprising the step of metering the amount of fluid injected through the fluid injection tube by changing the distance between the intake and outlet photoelectric sensors a predetermined distance.

15. The method according to Claim 12, and further comprising the step of connecting the lower end of the fluid injection tube into a T-connection that connects into the supply line and the discharge line.

16. The method according to Claim 12, and further comprising the step of metering the amount of fluid injected through the fluid injection tube by changing the fluid injection tube with a fluid injection tube having a different, predetermined bore size.

17. The method according to Claim 12, and further comprising the step of controlling the intake valve, outlet valve, and air valve by a programmable logic controller that receives sensed signals of fluid level within the fluid injection tube.

18. The method according to Claim 12, and further comprising the step of adjusting the amount of air pressure within the fluid injection tube via a precision air regulator that is connected into the pressure line of the air valve.

19. The method according to Claim 12, and further comprising the step of repeating the fluid cycle by opening the intake valve and allowing fluid to fill the fluid injection tube until sensed by the intake photoelectric sensor and then closing the intake valve .

20. The method according to Claim 12, wherein said fluid comprises an enzyme solution.