US20010020647A1 - Batch dispensing system for fluids - Google Patents
Batch dispensing system for fluids Download PDFInfo
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- US20010020647A1 US20010020647A1 US09/780,753 US78075301A US2001020647A1 US 20010020647 A1 US20010020647 A1 US 20010020647A1 US 78075301 A US78075301 A US 78075301A US 2001020647 A1 US2001020647 A1 US 2001020647A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F15/001—Means for regulating or setting the meter for a predetermined quantity
- G01F15/003—Means for regulating or setting the meter for a predetermined quantity using electromagnetic, electric or electronic means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F13/00—Apparatus for measuring by volume and delivering fluids or fluent solid materials, not provided for in the preceding groups
- G01F13/006—Apparatus for measuring by volume and delivering fluids or fluent solid materials, not provided for in the preceding groups measuring volume in function of time
Definitions
- the present invention is concerned with systems for dispensing fluid in batches of a desired size, that is, a desired mass or volume.
- fluids in batches of a desired size is a very common operation in many branches of industry.
- the term fluids in this connection covers a broad variety of flowable media such as true liquids, for example mineral oil products, beverages and liquid foodstuffs, gases, flowable solids such as fine powders, slurries etc.
- An example is the filling of containers for sale. The containers must be filled quickly to an exact amount. Repeated overfilling is as unacceptable for reasons of economy as repeated underfilling which might be considered fraudulous by customers or regulatory bodies. Incidents of container overflow because of excess overfilling, which can lead to contamination of production facilities, production stoppage and even dangerous situations such as fire hazard, must also be avoided.
- a typical batch dispensing system comprises a fluid duct equipped with a flowmeter and an electrically controlled flow controller, such as a valve or a pump, for starting and stopping fluid flow to a dispensing nozzle or the like.
- the valve or pump is controlled by a control unit which receives the flowmeter's output signal (the flow signal).
- the control unit includes a facility for setting a desired batch size, a start signal generator, an integrator or accumulator for integrating the flow signal over time and a comparator for generating a stop signal when the integrated or accumulated flow signal equals the desired batch size.
- the accumulator is reset to zero after each batch.
- Flowmeter, valve or pump and control unit may be separate or integrated units.
- the fluid to be dispensed is typically led to the dispensing system from a storage tank, a pressurized container, a feed pressure generating pump or the like via a length of tubing.
- the present invention provides a system for dispensing batches of fluid which comprises flow controlling means for starting a flow of fluid in response to a start signal and for subsequently stopping the flow of fluid in response to a stop signal, a flowmeter for measuring a flow rate of the fluid and generating a flow signal corresponding thereto, and a batch controller for generating the start signal, the batch controller receiving the flow signal and generating the stop signal in response thereto.
- the batch controller comprises storage means for storing a target batch size representation, integrating means for integrating the flow signal over time to develop a measured batch size representation, comparator means for comparing the target batch size representation with measured batch size representation and generating the stop signal when they are equal, and modifying means for modifying at least one of the target batch size representation and the measured batch size representation in response to the flow signal.
- the system according to the invention alleviates the problem of variations in feed pressure by providing a correction in response to the actually observed flow, instead of a correction based on a forecast from past history.
- correction principles associated with the invention may also applied to batch controllers for controlling batch dispensing systems, and to flowmeters for use in such systems.
- FIG. 1 is a schematic drawing of a typical batch dispensing system.
- FIG. 2 show the actual flow and the measured flow in the system of FIG. 1.
- FIG. 3 is a diagram illustrating the mass or volume in the system of FIG. 1 as actually dispensed and as determined by an integrator receiving the flow signal.
- FIG. 4 is a diagram of the actual flow and the measured flow in a dispensing system which has been simplified for purposes of calculation.
- FIG. 5 is a diagram similar to FIG. 4 illustrating a different valve closing characteristic.
- FIG. 6 is a block diagram of a prior art batch controller.
- FIGS. 7 and 8 are block diagrams of a batch dispensing system with flow-dependent modification of the comparator triggering point.
- FIG. 9 is a block diagram of a batch dispensing system with lead compensation of the flow signal for use with an unmodified batch controller.
- FIG. 10 shows the actual flow and a compensated flowmeter signal generated in the dispensing system of FIG. 9.
- FIG. 11 is a diagram illustrating the mass or volume in the system of FIG. 9 as actually dispensed and as determined by the integrator receiving the compensated flowmeter signal.
- FIG. 12 is a block diagram of a modified flowmeter having batch metering functionality, which may be used with a conventional batch dispensing controller in a system similar to that of FIG. 1.
- liquid 1 from a storage tank 2 is fed to a dispensing nozzle 3 via a feed line 4 equipped with an electronic flowmeter 5 and an electrically controlled shut-off valve 6 .
- Containers 7 to be filled with the liquid are conveyed to the nozzle 3 on a conveying system 8 .
- the dispensing operation is controlled by a batch controller 9 .
- the batch controller receives a flow signal 10 from the flowmeter 5 which indicates the instantaneous flow rate in the feed line 4 and thus the instantaneous flow rate of the liquid 1 dispensed at the nozzle 3 .
- the flowmeter may be a mass flowmeter or a volume flowmeter.
- the controller transmits start and stop signals 11 to the shutoff valve 6 to control the flow leaving the nozzle 3 .
- the valve opens on receiving a start signal and closes on receiving a stop signal.
- the controller 9 has a display 12 , a keyboard 13 , a start button 14 and a stop button 15 .
- the keyboard is used to enter a target batch size (a desired mass or volume of liquid to be filled into each container). Once the target batch size has been set and stored in the controller, the dispensing operation is started with the start button 14 .
- the controller operates the conveying system 8 via line 16 to convey a first container 7 into position below the nozzle 3 , where its presence is detected by a sensor 17 and signaled to the controller via line 18 .
- the controller then sends the start signal on line 11 to the valve 6 to start the flow and later sends the stop signal on line 11 to stop the flow when it has been determined from an integration of the flow signal 10 that the target batch size has been dispensed into the container 7 .
- the conveying and dispensing sequence is repeated until the stop button 15 on the controller is actuated.
- the thick curve 21 in FIG. 2 illustrates the variation in time of the flow leaving the nozzle 3 .
- the flow signal 22 (thin line in FIG. 2), that is, the response of the flowmeter 5 typically lags somewhat behind the actual flow 21 through the meter. This lagging behaviour is also illustrated in FIG. 2.
- the resulting mass or volume dispensed into the container 7 over time is illustrated in FIG. 3.
- the target batch size is indicated as M T .
- the actual batch size development is illustrated by the thick line 31 whereas the measured batch size development, which results from an integration of the flow signal 22 , is illustrated by the thin line 32 .
- a simple prior art batch controller is shown in FIG. 6.
- a logic unit 67 is connected with the start and stop buttons 14 and 15 .
- the logic unit 67 resets and enables an integrator 61 via lines 68 and 69 and sends the start signal to the valve 6 .
- the integrator 61 receives the flow signal 10 from flowmeter 5 .
- a target batch size memory 62 is set to hold the target batch size using the keyboard 13 .
- a comparator 63 compares the output signal 64 of the integrator 61 with the target batch size 65 and signals on line 66 when the target batch size is achieved.
- the logic unit 67 receives the trigger 66 and stops the flow.
- the logic unit also handles the conveying functions which need not be detailed.
- the target batch size 65 must be set to a value which is smaller than the actually desired batch size to compensate for flowmeter lag and slow valve closing, as has been explained above.
- ⁇ f is a characteristic time constant of the flowmeter.
- M b M T +M v 32 Q 0 T+Q 0 ⁇ v . (6)
- FIG. 5 serves to show that similar considerations apply if the valve closing characteristic is not exponential but linear as shown by line 51 ; it is immediately apparent that the mass or volume delivered during the closing of the valve is equal to
- T v ′ is defined as half the closing time of the valve. It can thus be said that the required comparator setting will generally be of the form of equation (7a) if ⁇ v is properly defined.
- the target batch size value, or comparator setpoint M S may be allowed to float with the flowmeter signal q f . Because of the inherent timing of the process the comparator trigger value M S will be in place and up-to-date with respect to the actual flow when the flow integration process gets near to it.
- FIGS. 7 and 8 take advantage of this observation.
- the flow signal is delivered in the form of digital samples on line 10 to a multiplier unit 71 and to a an integrator 61 .
- the sum of the system time constants ⁇ f + ⁇ v is input to the multiplier unit 71 via the keyboard 13 .
- the product q f ( ⁇ f + ⁇ v ) of the sum of the system time constants and the flowmeter signal generated by the unit is passed on to a subtracting unit 72 where it is subtracted from the target batch size held in the target batch size memory 62 .
- the modified target batch size, or comparator trigger value M S is then passed on to the comparator 63 where it is compared to the integrated flow signal from integrator 71 .
- This is a direct realization of equation (12).
- FIGS. 7 and 8 both require that modifications be made to the traditional batch controller shown in FIG. 6. It is possible, however, to achieve substantially the same flow-dependent correction of the target batch size by modification of the flowmeter. This will now be explained.
- ⁇ dot over (q) ⁇ f means the time derivative of the flowmeter signal q f .
- batch dispensing operation can be compensated for the combined effect of the lag time of the flowmeter and the closing time of the valve or stopping time of the pump by adding to the flowmeter signal q f its own derivate multiplied by the sum of the system time constants, and performing the integration on the sum.
- a flowmeter signal modified this way can be fed directly into a conventional batch controller such as that shown in FIG. 6.
- a batch dispensing system controller incorporating this approach is shown in FIG. 9.
- the flowmeter signal on line 10 is fed to a differentiating unit 91 which generates the time derivative of the flowmeter signal.
- a multiplier unit 92 receives the time derivative signal and multiplies it with the sum of the system time constants ( ⁇ f + ⁇ v ) which has been entered using the keyboard 13 .
- the multiplied derivative is added to the flowmeter signal by an adder 93 , and the resulting sum is fed to the integrator 61 .
- the comparator 63 compares the integrated sum signal to the target batch size in memory 62 . In this instance, the target batch size can be entered directly; the operator does not need to make any manual compensation.
- the thick curve 101 shows the actual flow dispensed from the nozzle 3 and the thin curve 102 shows the compensated flow signal at the output of the adder 93 in FIG. 9. It can be seen that the compensation causes an overshoot whose magnitude is dependent on the multiplication factor ( ⁇ f + ⁇ v ) entered into the system of FIG. 9 via the keyboard 13 .
- the effect of the compensation on the comparator setpoint M S is illustrated in FIG. 11.
- the thick curve 111 shows the actual flow dispensed from the nozzle 3 (see FIG. 1) and the thin curve 112 shows the output signal of the integrator 61 in FIG. 9.
- the compensation will cause the integrated signal to reach M S early; thus the stop signal for the valve 6 (see FIG. 1) will be generated so early that the container is filled to the exact target batch mass or volume M b during the closing time of the valve 6 .
- FIG. 12 shows substantially the same system as FIG. 9 wherein the flowmeter and the functional units for compensating the flowmeter signal have been united and supplemented with a separate keyboard 121 and a keyboard-controlled selecting switch 122 to provide a versatile batch flowmeter 5 ′.
- the flowmeter 5 ′ functions as a conventional flowmeter.
- the output signal of the flowmeter 5 ′ results from an addition of the flow signal 10 with its own time derivative muliplied by a compensation factor ( ⁇ f + ⁇ v ) which can be entered via the keyboard 121 .
- the flowmeter 5 ′ can be switched to provide a normal flow signal or a flow signal compensated for batch metering, and the compensation is variable by entering the proper compensation factor via the keyboard. This allows an adaptation of the flowmeter 5 ′ to batch dispensing systems having different closing times or stopping times of the dispensing valve or pump.
- the lead filter Given a sequence of sampled flow signal values (x l ), the lead filter would be constructed to output a sequence of filtered signal values (y i ) formed as
- t samp is the sampling time interval
- the sequence (y l ) of samples generated by such a lead filter is equivalent to the modified flow signal 102 generated by the combination of the differentiator 91 , the multiplier 92 and the adder 93 in FIG. 9, and digital summation of the sequence (y i ) is equivalent to the integration performed by integrator 61 .
- the variable lead filter could be a single unit which would be substitued for the elements 91 , 92 and 93 in a digital realization of the principles of the invention.
- the lead filter would receive the time factor ( ⁇ f + ⁇ v ) from the keyboard 13 in FIG. 9.
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Abstract
Description
- The present invention is concerned with systems for dispensing fluid in batches of a desired size, that is, a desired mass or volume.
- The dispensing of fluids in batches of a desired size is a very common operation in many branches of industry. The term fluids in this connection covers a broad variety of flowable media such as true liquids, for example mineral oil products, beverages and liquid foodstuffs, gases, flowable solids such as fine powders, slurries etc. An example is the filling of containers for sale. The containers must be filled quickly to an exact amount. Repeated overfilling is as unacceptable for reasons of economy as repeated underfilling which might be considered fraudulous by customers or regulatory bodies. Incidents of container overflow because of excess overfilling, which can lead to contamination of production facilities, production stoppage and even dangerous situations such as fire hazard, must also be avoided.
- A typical batch dispensing system comprises a fluid duct equipped with a flowmeter and an electrically controlled flow controller, such as a valve or a pump, for starting and stopping fluid flow to a dispensing nozzle or the like. The valve or pump is controlled by a control unit which receives the flowmeter's output signal (the flow signal). The control unit includes a facility for setting a desired batch size, a start signal generator, an integrator or accumulator for integrating the flow signal over time and a comparator for generating a stop signal when the integrated or accumulated flow signal equals the desired batch size. The accumulator is reset to zero after each batch. Flowmeter, valve or pump and control unit may be separate or integrated units. The fluid to be dispensed is typically led to the dispensing system from a storage tank, a pressurized container, a feed pressure generating pump or the like via a length of tubing.
- The starting and stopping of the fluid flow in a dispensing system of the kind described makes it difficult to dispense exact batches. Most flowmeters follow changes in flow rate only with a certain time lag. Thus the measured flow will be smaller than the actual flow at least for some time after start, and the mass or volume measured by integration of the measured flow will be less than the actual mass or volume dispensed. Valves and pumps also take a certain time to close or stop which means that the integrator must develop a stop signal ahead of the time when flow must actually stop to result in an exact batch.
- These problems are addressed in U.S. Pat. No. 5,431,302. The document describes a batch dispensing system with a flow controlling valve wherein the actual overfill is averaged over a number of batches. The average overfill is then used to cause an earlier closure of the valve so that subsequent batches will be filled exactly.
- However the batch metering problem is compounded by the fact that typically the feed pressure of the fluid to be dispensed and thus the maximum flow rate occurring in each individual batch is not constant over time. In the general examples given above, the feed pressure decreases with the fluid head in the storage tank, or with the pressure in the pressurized container, as they are increasingly emptied. In more complicated process environments quite erratic feed pressure variations may occur. This is a problem which cannot be solved with the approach of U.S. Pat. No. 5,431,302.
- To address this problem, the present invention provides a system for dispensing batches of fluid which comprises flow controlling means for starting a flow of fluid in response to a start signal and for subsequently stopping the flow of fluid in response to a stop signal, a flowmeter for measuring a flow rate of the fluid and generating a flow signal corresponding thereto, and a batch controller for generating the start signal, the batch controller receiving the flow signal and generating the stop signal in response thereto. The batch controller comprises storage means for storing a target batch size representation, integrating means for integrating the flow signal over time to develop a measured batch size representation, comparator means for comparing the target batch size representation with measured batch size representation and generating the stop signal when they are equal, and modifying means for modifying at least one of the target batch size representation and the measured batch size representation in response to the flow signal.
- The system according to the invention alleviates the problem of variations in feed pressure by providing a correction in response to the actually observed flow, instead of a correction based on a forecast from past history.
- The correction principles associated with the invention may also applied to batch controllers for controlling batch dispensing systems, and to flowmeters for use in such systems.
- Preferred embodiments of the invention will now be described below with reference to the accompanying drawings.
- FIG. 1 is a schematic drawing of a typical batch dispensing system.
- FIG. 2 show the actual flow and the measured flow in the system of FIG. 1.
- FIG. 3 is a diagram illustrating the mass or volume in the system of FIG. 1 as actually dispensed and as determined by an integrator receiving the flow signal.
- FIG. 4 is a diagram of the actual flow and the measured flow in a dispensing system which has been simplified for purposes of calculation.
- FIG. 5 is a diagram similar to FIG. 4 illustrating a different valve closing characteristic.
- FIG. 6 is a block diagram of a prior art batch controller.
- FIGS. 7 and 8 are block diagrams of a batch dispensing system with flow-dependent modification of the comparator triggering point.
- FIG. 9 is a block diagram of a batch dispensing system with lead compensation of the flow signal for use with an unmodified batch controller.
- FIG. 10 shows the actual flow and a compensated flowmeter signal generated in the dispensing system of FIG. 9.
- FIG. 11 is a diagram illustrating the mass or volume in the system of FIG. 9 as actually dispensed and as determined by the integrator receiving the compensated flowmeter signal.
- FIG. 12 is a block diagram of a modified flowmeter having batch metering functionality, which may be used with a conventional batch dispensing controller in a system similar to that of FIG. 1.
- In the batch dispensing system of FIG. 1,
liquid 1 from astorage tank 2 is fed to a dispensingnozzle 3 via afeed line 4 equipped with an electronic flowmeter 5 and an electrically controlled shut-off valve 6.Containers 7 to be filled with the liquid are conveyed to thenozzle 3 on aconveying system 8. The dispensing operation is controlled by a batch controller 9. - The batch controller receives a
flow signal 10 from the flowmeter 5 which indicates the instantaneous flow rate in thefeed line 4 and thus the instantaneous flow rate of theliquid 1 dispensed at thenozzle 3. Depending on the application the flowmeter may be a mass flowmeter or a volume flowmeter. The controller transmits start and stop signals 11 to the shutoff valve 6 to control the flow leaving thenozzle 3. The valve opens on receiving a start signal and closes on receiving a stop signal. - The controller9 has a
display 12, akeyboard 13, astart button 14 and astop button 15. The keyboard is used to enter a target batch size (a desired mass or volume of liquid to be filled into each container). Once the target batch size has been set and stored in the controller, the dispensing operation is started with thestart button 14. The controller operates theconveying system 8 vialine 16 to convey afirst container 7 into position below thenozzle 3, where its presence is detected by a sensor 17 and signaled to the controller vialine 18. The controller then sends the start signal on line 11 to the valve 6 to start the flow and later sends the stop signal on line 11 to stop the flow when it has been determined from an integration of theflow signal 10 that the target batch size has been dispensed into thecontainer 7. The conveying and dispensing sequence is repeated until thestop button 15 on the controller is actuated. - The
thick curve 21 in FIG. 2 illustrates the variation in time of the flow leaving thenozzle 3. The start signal is sent at t=0, and the stop signal is sent at t=T. When the valve 6 opens at t=0, theflow 21 gradually builds up to a maximum value Q0. When the valve 6 receives the stop signal at t=T, it starts to close and theflow rate 21 is gradually reduced to zero. The flow signal 22 (thin line in FIG. 2), that is, the response of the flowmeter 5 typically lags somewhat behind theactual flow 21 through the meter. This lagging behaviour is also illustrated in FIG. 2. - The resulting mass or volume dispensed into the
container 7 over time is illustrated in FIG. 3. The target batch size is indicated as MT. The actual batch size development is illustrated by thethick line 31 whereas the measured batch size development, which results from an integration of theflow signal 22, is illustrated by thethin line 32. - It is evident from FIG. 3 that the combined effect of the flowmeter's time lag and the slow closing of the valve causes a need to generate the stop signal at a time T when the measured batch size is still below the target batch size MT. The batch controller must therefore be set to trigger the stop signal when the dispensed mass or volume reaches the stop level MS.
- A simple prior art batch controller is shown in FIG. 6. A
logic unit 67 is connected with the start and stopbuttons logic unit 67 resets and enables an integrator 61 vialines flow signal 10 from flowmeter 5. A targetbatch size memory 62 is set to hold the target batch size using thekeyboard 13. Acomparator 63 compares the output signal 64 of the integrator 61 with thetarget batch size 65 and signals online 66 when the target batch size is achieved. Thelogic unit 67 receives thetrigger 66 and stops the flow. The logic unit also handles the conveying functions which need not be detailed. - In the prior art controller of FIG. 6, the
target batch size 65 must be set to a value which is smaller than the actually desired batch size to compensate for flowmeter lag and slow valve closing, as has been explained above. - In the diagram of FIG. 4 it is assumed for simplicity that the actual flow q,
line 41, rises stepwise to its steady-state value Q0 and that thestep response 42 of the flowmeter signal qf is - q f(t)=Q 0(1−exp(−t/τ f) (1)
- wherein τf is a characteristic time constant of the flowmeter.
- The true batch mass or volume delivered up to the time T is
- M T =Q 0 T (2)
-
- The valve is also assumed for simplicity to close exponentially according to the equation
- q v =Q 0 exp(−t/τ v) (4)
- wherein qv is the flow out of the
nozzle 3 during the closing of the valve, indicated as the part ofcurve 41 delimiting the hatchedarea 44 in FIG. 4, and τv is a characteristic time constant of the valve 6. The valve closing contributes an additional mass or volume which is dispensed after the time T, which may be found by integrating equation (4) as t,0081 - and which is shown as hatched
area 44. This results in a total actually delivered batch mass or volume of - M b =M T +M v 32 Q 0 T+Q 0τv. (6)
- By combining equations (3) and (6) we find that
- M f =M b −Q 0(τf+τv) (7)
- or, in words, the result of the integration of the flowmeter signal up to the time T when the stop signal needs to be given, is less than the mass or volume actually dispensed by the dispensing system, by the amount Q0 (τf+τv).
- In other words, with the assumptions of FIG. 4, the comparator must be set to trigger at the value
- M S =M b −Q 0(τf+τv) (7a)
- to cause an exact dispensing of a desired batch mass or volume Mb.
- FIG. 5 serves to show that similar considerations apply if the valve closing characteristic is not exponential but linear as shown by
line 51; it is immediately apparent that the mass or volume delivered during the closing of the valve is equal to - M v ′=Q 0τv′ (8)
- wherein Tv′ is defined as half the closing time of the valve. It can thus be said that the required comparator setting will generally be of the form of equation (7a) if τv is properly defined.
- Referring now again to FIG. 1 it can be seen that the pressure in the
feed line 4 will vary with the level h of the liquid in thestorage tank 2. This pressure variation causes a variation in the steady state flow rate Q0 which influences on the batch metering process. - With equation (7a) above rearranged as
- M b =M S +Q 0(τf+τv) (9)
- we will now consider the effect of a change ΔQ0 in the steady state flow rate Q0 brought about by a change ΔP in the feed pressure in
line 4. The change ΔQ0 will leave the trigger point setting MS of the comparator unchanged. This means that the amount Mf metered out by the flowmeter before the comparator triggers the closing of the valve will remain unchanged, because the triggering will just occur correspondingly earlier or later in time. However, the change will bring about a change in the mass or volume which is actually dispensed but not measured by the flowmeter because of its lag time, and in the mass or volume Mv which is dispensed during the closing of the valve. Thus the change ΔQ0 causes a change ΔMb which can be expressed as - ΔM b=(τf+τv)ΔQ 0. (10)
- Requiring that the resulting batch mass or volume be unchanged (ΔMb=0) we find that the target batch size or comparator setting must be changed correspondingly:
- ΔM S=−(τf+τv)ΔQ 0. (11)
- From an inspection of FIGS. 2 and 3 it becomes apparent that the flowmeter signal qf generally rises to the steady state flow value Q0 well before the integrator reaches its setpoint Mf. This allows the generalization that equations (7) and (11) can be cast in the general form
- M S =M b −q f(τf+τv) (12)
- which means that the target batch size value, or comparator setpoint MS, may be allowed to float with the flowmeter signal qf. Because of the inherent timing of the process the comparator trigger value MS will be in place and up-to-date with respect to the actual flow when the flow integration process gets near to it.
- The batch dispensing systems shown in FIGS. 7 and 8 take advantage of this observation. In the system of FIG. 7, which shows a digital realization, the flow signal is delivered in the form of digital samples on
line 10 to amultiplier unit 71 and to a an integrator 61. The sum of the system time constants τf+τv is input to themultiplier unit 71 via thekeyboard 13. The product qf (τf+τv) of the sum of the system time constants and the flowmeter signal generated by the unit is passed on to a subtractingunit 72 where it is subtracted from the target batch size held in the targetbatch size memory 62. The modified target batch size, or comparator trigger value MS is then passed on to thecomparator 63 where it is compared to the integrated flow signal fromintegrator 71. This is a direct realization of equation (12). - In the dispensing system of FIG. 8 the product qf (τf+τv) generated by
multiplier unit 71 is added to the output signal of integrator 61 by means ofadder 81. The sum is then passed to the comparator for comparison with the target batch size value entered into thebatch size memory 62 via thekeyboard 13. This corresponds to a rearrangement of equation (12) to give the Mb in terms of MS and qf (τf+τv). As in FIG. 7 the sum of the system time constants τf+τv is input to themultiplier unit 71 via thekeyboard 13. All other elements in FIGS. 7 and 8 perform the same functions as their counterparts in FIG. 6 having the same reference numbers, andelements - The systems of FIGS. 7 and 8 both require that modifications be made to the traditional batch controller shown in FIG. 6. It is possible, however, to achieve substantially the same flow-dependent correction of the target batch size by modification of the flowmeter. This will now be explained.
- Starting from the slightly simplified situation of FIG. 4 and equation (1) again, we have
- q f(t)=Q 0(1−exp(−t/τ f) (1)
-
- wherein {dot over (q)}f means the time derivative of the flowmeter signal qf.
- This means that batch dispensing operation can be compensated for the combined effect of the lag time of the flowmeter and the closing time of the valve or stopping time of the pump by adding to the flowmeter signal qf its own derivate multiplied by the sum of the system time constants, and performing the integration on the sum. A flowmeter signal modified this way can be fed directly into a conventional batch controller such as that shown in FIG. 6.
- A batch dispensing system controller incorporating this approach is shown in FIG. 9. The flowmeter signal on
line 10 is fed to a differentiating unit 91 which generates the time derivative of the flowmeter signal. Amultiplier unit 92 receives the time derivative signal and multiplies it with the sum of the system time constants (τf+τv) which has been entered using thekeyboard 13. The multiplied derivative is added to the flowmeter signal by anadder 93, and the resulting sum is fed to the integrator 61. Thecomparator 63 compares the integrated sum signal to the target batch size inmemory 62. In this instance, the target batch size can be entered directly; the operator does not need to make any manual compensation. - In FIG. 10, the thick curve101 shows the actual flow dispensed from the
nozzle 3 and thethin curve 102 shows the compensated flow signal at the output of theadder 93 in FIG. 9. It can be seen that the compensation causes an overshoot whose magnitude is dependent on the multiplication factor (τf+τv) entered into the system of FIG. 9 via thekeyboard 13. - The effect of the compensation on the comparator setpoint MS is illustrated in FIG. 11. The thick curve 111 shows the actual flow dispensed from the nozzle 3 (see FIG. 1) and the
thin curve 112 shows the output signal of the integrator 61 in FIG. 9. The effect of the overshoot caused by the compensation of the flow signal is that the comparator can be set at MS=Mb. The compensation will cause the integrated signal to reach MS early; thus the stop signal for the valve 6 (see FIG. 1) will be generated so early that the container is filled to the exact target batch mass or volume Mb during the closing time of the valve 6. - FIG. 12 shows substantially the same system as FIG. 9 wherein the flowmeter and the functional units for compensating the flowmeter signal have been united and supplemented with a separate keyboard121 and a keyboard-controlled selecting
switch 122 to provide a versatile batch flowmeter 5′. With theswitch 122 in the position as shown, the flowmeter 5′ functions as a conventional flowmeter. With theswitch 122 in the other position, the output signal of the flowmeter 5′ results from an addition of theflow signal 10 with its own time derivative muliplied by a compensation factor (τf+τv) which can be entered via the keyboard 121. Thus the flowmeter 5′ can be switched to provide a normal flow signal or a flow signal compensated for batch metering, and the compensation is variable by entering the proper compensation factor via the keyboard. This allows an adaptation of the flowmeter 5′ to batch dispensing systems having different closing times or stopping times of the dispensing valve or pump. - It should be mentioned in closing that the combined effect of generating a time derivative of the flow signal, multiplying the time derivative with a time constant to provide a multiplied derivative signal and adding the multiplied derivative signal to the flow signal can be performed by filtering the flow signal with a digital signal processing filter known as a variable lead filter.
- Given a sequence of sampled flow signal values (xl), the lead filter would be constructed to output a sequence of filtered signal values (yi) formed as
- y i =x l+((x i −x i−1)(τf+τv)/t samp) (14)
- wherein tsamp is the sampling time interval.
- The sequence (yl) of samples generated by such a lead filter is equivalent to the modified
flow signal 102 generated by the combination of the differentiator 91, themultiplier 92 and theadder 93 in FIG. 9, and digital summation of the sequence (yi) is equivalent to the integration performed by integrator 61. In other words, the variable lead filter could be a single unit which would be substitued for theelements keyboard 13 in FIG. 9.
Claims (18)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/125,315 US6499517B2 (en) | 2000-02-11 | 2002-04-18 | Batch dispensing system for fluids |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DKPA200000216 | 2000-02-11 | ||
DK200000216A DK174559B1 (en) | 2000-02-11 | 2000-02-11 | System for measuring portions of fluid |
DK200000216 | 2000-02-11 |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/125,315 Division US6499517B2 (en) | 2000-02-11 | 2002-04-18 | Batch dispensing system for fluids |
Publications (2)
Publication Number | Publication Date |
---|---|
US20010020647A1 true US20010020647A1 (en) | 2001-09-13 |
US6397906B2 US6397906B2 (en) | 2002-06-04 |
Family
ID=8159115
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/780,753 Expired - Fee Related US6397906B2 (en) | 2000-02-11 | 2001-02-09 | Batch dispensing system for fluids |
US10/125,315 Expired - Fee Related US6499517B2 (en) | 2000-02-11 | 2002-04-18 | Batch dispensing system for fluids |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/125,315 Expired - Fee Related US6499517B2 (en) | 2000-02-11 | 2002-04-18 | Batch dispensing system for fluids |
Country Status (3)
Country | Link |
---|---|
US (2) | US6397906B2 (en) |
EP (1) | EP1132722A3 (en) |
DK (1) | DK174559B1 (en) |
Cited By (6)
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US20040124253A1 (en) * | 2002-10-17 | 2004-07-01 | Bergwin Gregory A. | Injection apparatus for irrigation system |
US6811301B2 (en) | 2002-03-29 | 2004-11-02 | Hydreclaim, Inc. | Feeder control system for an automated blender system |
US20060060602A1 (en) * | 2004-09-21 | 2006-03-23 | Kwang-Chae Jeong | Flow control feedback system and method of automatically controlling fluid flow |
DE102005035264A1 (en) * | 2005-07-25 | 2007-02-01 | Endress + Hauser Flowtec Ag | Flow meter e.g. ultrasound flow meter, for use in filling system, has memory unit for storing control data for controlling and/or regulating filling of medium in filling container, and sensor determining process conditions of medium |
CN111896064A (en) * | 2020-06-30 | 2020-11-06 | 中国北方发动机研究所(天津) | High-precision fuel oil consumption measuring device |
US10926894B2 (en) | 2016-04-06 | 2021-02-23 | Syntegon Technology Gmbh | Apparatus for bagging a product |
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JP3976302B2 (en) * | 2000-08-29 | 2007-09-19 | 富士フイルム株式会社 | Weighing device |
FR2838824B1 (en) * | 2002-04-19 | 2005-02-04 | Sogem Fl | METHOD AND DEVICE FOR AUTOMATICALLY CONTROLLING A QUANTITY OF PRODUCT REPETITIVELY DEPOSITED BY A REMOVAL ACTUATOR, AND THE REMOVAL INSTALLATION EQUIPPED WITH SUCH A DEVICE |
DK174757B1 (en) * | 2002-05-24 | 2003-10-20 | Siemens Flow Instr As | Mass flow meter with integration of acceleration forces on pipes and system using mass flow meter |
US20040026334A1 (en) * | 2002-08-07 | 2004-02-12 | The University Of Iowa Research Foundation | Method for removing hydrogen sulfide and increasing the rate of biodegradation in animal waste pits and lagoons |
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ITVR20020101A1 (en) * | 2002-10-16 | 2004-04-17 | Moretto Plastics Automation S R L | METHOD AND DOSING AND / OR ADDITIVE DEVICE AD |
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US20050274200A1 (en) * | 2004-05-25 | 2005-12-15 | Henry Manus P | Flowmeter batching techniques |
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US2755999A (en) * | 1952-05-17 | 1956-07-24 | Gen Motors Corp | Temperature measuring and control apparatus |
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GB8502580D0 (en) | 1985-02-01 | 1985-03-06 | Kodak Ltd | Metered liquid delivery systems |
FR2616222A1 (en) * | 1987-06-02 | 1988-12-09 | Schlumberger Cie Dowell | MEANS FOR DOSING LIQUID WITH HIGH DYNAMICS OF VOLUMES AND VISCOSITIES AND APPLICATIONS IN PARTICULAR TO OILS IN THE OIL SECTOR |
JP2580054B2 (en) * | 1990-01-25 | 1997-02-12 | 日産自動車株式会社 | Air flow measurement device |
IT1272579B (en) * | 1993-09-07 | 1997-06-23 | Tetra Dev Co | EQUIPMENT FOR FILLING PACKAGING CONTAINERS |
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US5996650A (en) * | 1996-11-15 | 1999-12-07 | Oden Corporation | Net mass liquid filler |
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-
2000
- 2000-02-11 DK DK200000216A patent/DK174559B1/en not_active IP Right Cessation
-
2001
- 2001-01-24 EP EP01200231A patent/EP1132722A3/en not_active Withdrawn
- 2001-02-09 US US09/780,753 patent/US6397906B2/en not_active Expired - Fee Related
-
2002
- 2002-04-18 US US10/125,315 patent/US6499517B2/en not_active Expired - Fee Related
Cited By (7)
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US6811301B2 (en) | 2002-03-29 | 2004-11-02 | Hydreclaim, Inc. | Feeder control system for an automated blender system |
US20040124253A1 (en) * | 2002-10-17 | 2004-07-01 | Bergwin Gregory A. | Injection apparatus for irrigation system |
US20060060602A1 (en) * | 2004-09-21 | 2006-03-23 | Kwang-Chae Jeong | Flow control feedback system and method of automatically controlling fluid flow |
DE102005035264A1 (en) * | 2005-07-25 | 2007-02-01 | Endress + Hauser Flowtec Ag | Flow meter e.g. ultrasound flow meter, for use in filling system, has memory unit for storing control data for controlling and/or regulating filling of medium in filling container, and sensor determining process conditions of medium |
DE102005035264B4 (en) * | 2005-07-25 | 2018-04-12 | Endress + Hauser Flowtec Ag | Control of a filling of a medium |
US10926894B2 (en) | 2016-04-06 | 2021-02-23 | Syntegon Technology Gmbh | Apparatus for bagging a product |
CN111896064A (en) * | 2020-06-30 | 2020-11-06 | 中国北方发动机研究所(天津) | High-precision fuel oil consumption measuring device |
Also Published As
Publication number | Publication date |
---|---|
US6499517B2 (en) | 2002-12-31 |
EP1132722A2 (en) | 2001-09-12 |
US6397906B2 (en) | 2002-06-04 |
DK200000216A (en) | 2001-08-12 |
DK174559B1 (en) | 2003-06-02 |
EP1132722A3 (en) | 2007-01-03 |
US20020139437A1 (en) | 2002-10-03 |
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