WO2021034244A1

WO2021034244A1 - Arrangement and method for dosing cleaning agent

Info

Publication number: WO2021034244A1
Application number: PCT/SE2020/050744
Authority: WO
Inventors: Epke Bosma
Original assignee: Delaval Holding Ab
Priority date: 2019-08-19
Filing date: 2020-07-22
Publication date: 2021-02-25

Abstract

An arrangement (1) for dairy applications, for dosing cleaning agent into a fluid. The arrangement (1) comprises a fluid circuit (31), a diaphragm pump (3) arranged to provide a flow of cleaning agent in the fluid circuit (31) from a cleaning agent source (4) and a dosing valve (5) arranged to the fluid circuit (31) downstream the diaphragm pump (3). The dosing valve (5) is configured to regulate a dosage of cleaning agent from the diaphragm pump (3) to a collection container (25). The arrangement (1) further comprises a control arrangement (20) configured to control the dosing valve (5) to regulate the dosage, such that a dosed volume of cleaning agent passed to the collection container (25) is correlated with a volume of fluid being passed to the collection container (25), in order to obtain a target concentration of cleaning agent in the fluid in the collection container (25). The disclosure also relates to a method for dosing cleaning agent into a fluid.

Description

Arrangement and method for dosing cleaning agent Technical Field

The present disclosure relates to dosing, and in particular dosing cleaning agents into a fluid for cleaning fluid circuits in dairy applications.

Background

In dairy industry, Cleaning In Place (CIP) systems are often used for cleaning the interior surfaces of pipelines and vessels used for transporting and storing the dairy, such as milk. A CIP system cleans the interior surfaces of the pipelines, vessels and associated things without dismantling. The CIP system should remove any remaining organic contamination, milk and water plaque. The CIP system may use both cleaning agents and heat to perform the cleaning. The cleaning involves circulating water and cleaning agent in the pipelines and vessels of the dairy system in a dairy plant or dairy farm.

A typical cleaning procedure for a dairy system comprises a plurality of steps. The procedure comprises mixing a cleaning agent into water to provide a cleaning solution. The cleaning agent may include detergent, sanitizer or disinfectant, or a mix thereof. The cleaning solution is circulated in the dairy fluid circuit of the dairy system for a period of time, while maintaining the temperature of the cleaning solution at a high temperature. Thereafter, the dairy fluid circuit is rinsed. The dairy fluid circuit may be cleaned several times a day. During cleaning, the dairy fluid circuit cannot be used, and typically the cleaning should be able to be performed in a certain time to reduce downtime. The dairy fluid circuit may be several hundred meters long, and the cleaning may consume a considerable amount of cleaning solution.

Summary

In order to clean the dairy fluid circuit of the dairy system accurately, it is important that the cleaning solution has an accurate concentration of cleaning agent. It is an object of the disclosure to provide an accurate dosing of cleaning agent. It is a further object to provide an accurate dosing to a low cost. It is a still further object of the disclosure to provide an accurate dosing that is easily configurable for different amounts of cleaning solutions.

These objects and others are at least partly achieved by the arrangement and the method according to the independent claims, and by the embodiments according to the dependent claims.

According to a first aspect, the disclosure relates to an arrangement for dairy applications, for dosing cleaning agent into a fluid. The arrangement comprises a fluid circuit, a diaphragm pump arranged to provide a flow of cleaning agent in the fluid circuit from a cleaning agent source, and a dosing valve arranged to the fluid circuit downstream the diaphragm pump. The dosing valve is configured to regulate a dosage of cleaning agent from the diaphragm pump to a collection container. The arrangement also comprises a control arrangement configured to control the dosing valve to regulate the dosage, such that a dosed volume of cleaning agent passed to the collection container is correlated with a volume of fluid being passed to the collection container, in order to obtain a target concentration of cleaning agent in the fluid in the collection container.

The arrangement provides a more accurate dosing compared to other known solutions using for example peristaltic pumps, as the arrangement is less prone to wear than such solutions. The diaphragm pump together with the dosing valve provides a reliable and robust solution, as standard and well-known components can be used. As standard components may be used, the cost for the arrangement may be kept low, compared to solutions that are custom made. By regulating the dosing valve, the arrangement may be easily changed to provide varying concentrations of cleaning agent according to needs.

According to some embodiments, the dosed volume of cleaning agent and the volume of fluid being passed to the collection container are passed to the collection container during the same period of time. Thus, the dosed volume of cleaning agent and the volume of fluid being passed to the collection container are correlated in time.

According to some embodiments, the arrangement comprises a pump stroke sensor configured to detect pump strokes of the diaphragm pump. The control arrangement is configured to obtain information of the detected pump strokes, and to control the dosing valve also based on information of the detected pump strokes. Thereby, the dosed volume of cleaning agent may be corrected such that the target concentration of cleaning agent is obtained.

According to some embodiments, the control arrangement is configured to estimate a current dosed volume of cleaning agent, dosed by the dosing valve, based on the information of the detected pump strokes and a predetermined pump stroke volume. Thus, the current dosed volume of cleaning agent may be determined. This current dosed volume is for example notified to the operator, and/or used for controlling the dosing valve.

According to some embodiments, the control arrangement is configured to determine information indicative of a total opening time of the dosing valve between the detected pump strokes. The control arrangement is also configured to control the dosing valve to regulate the dosage, based on the information indicative of a total opening time of the dosing valve between the detected pump strokes and the correspondingly estimated dosed volume of cleaning agent during a same period of time, such that the target concentration of cleaning agent in the fluid in the collection container is obtained. Thereby, properties such as opening time of the dosing valve may directly controlled to a correct value, based on the current opening time of the dosing valve.

According to some embodiments, the diaphragm pump is air driven, and the pump stroke sensor is a pressure sensor arranged to sense exhaust air from the diaphragm pump. Thus, a standard, well-known diaphragm pump can be used, that does not need any lubrication or have parts that easily wear out. According to some embodiments, the pump stroke sensor is external to the diaphragm pump. Thus, there is no need to re-construct the standard diaphragm pump.

According to some embodiments, the dosing valve is an on/off valve or a control valve. Hence, an ordinary valve may be used.

According to some embodiments, the diaphragm pump is halted when the dosing valve is closed. Thus, the speed of the diaphragm pump is dependent on the opening degree of the dosing valve.

According to some embodiments, the control arrangement is configured to control the dosing valve to an open state for a period of time correlated with a volume of fluid of a predetermined amount being passed to the collection container. Thus, the opening time of the dosing valve is regulated such that a target concentration of cleaning agent is achieved.

According to some embodiments, the control arrangement is configured to obtain a flow rate of fluid being passed to the collection container. Thus, the control arrangement may use the flow rate of the fluid to control the volume of cleaning agent being passed to the collection container.

According to some embodiments, the control arrangement is configured to calculate the volume of fluid being passed to the collection container, based on the flow rate of fluid being passed to the collection container. Thus, the control arrangement may use the volume of the fluid to control the volume of cleaning agent being passed to the collection container.

According to some embodiments, the control arrangement is not using a flow rate sensor for measuring a flow rate of dosed cleaning agent. Thus, there is no need to measure the flow rate of dosed cleaning agent to control the dosage of cleaning agent to the collection container.

According to some embodiments, the arrangement comprises one or several dosing branches comprising: an additional diaphragm pump arranged to provide a flow of cleaning agent in the fluid circuit from an additional cleaning agent source, and an additional dosing valve arranged to the flow circuit downstream the additional diaphragm pump. The additional dosing valve is configured to regulate a dosage of cleaning agent from the additional diaphragm pump to the collection container. Thus, a plurality of different cleaning agents may be dosed using the same dosing arrangement.

According to some embodiments, the dosed volume of cleaning agent passed to the collection container is between 5 and 50 ml, and the volume of fluid being passed to the collection container is between 1000 and 3000 ml.

According to a second aspect, the disclosure relates to a corresponding method for dosing cleaning agent into a fluid. The method comprises providing, using a diaphragm pump, a flow of cleaning agent in a fluid circuit from a cleaning agent source. The method further comprises controlling a dosing valve to regulate a dosage of cleaning agent from the diaphragm pump to a collection container, such that a dosed volume of cleaning agent passed to the collection container is correlated with a volume of fluid being passed to the collection container, in order to obtain a target concentration of cleaning agent in the fluid in the collection container.

According to some embodiments, the dosed volume of cleaning agent and the volume of fluid being passed to the collection container are passed to the collection container during the same period of time. According to some embodiments, the method comprises detecting pump strokes of the diaphragm pump and controlling the dosing valve also based on information of the detected pump strokes.

According to some embodiments, the method comprises estimating a current volume of dosed cleaning agent based on the information of the detected pump strokes and a predetermined pump stroke volume.

According to some embodiments, the method comprises determining information indicative of a total opening time of the dosing valve between the detected pump strokes. The method further comprises controlling the dosing valve to regulate the dosage, based on the information indicative of the total opening time of the dosing valve between the detected pump strokes and the correspondingly estimated current dosed volume of cleaning agent during a same period of time, such that the target concentration of cleaning agent in the fluid in the collection container is obtained.

According to some embodiments, the controlling comprises halting the diaphragm pump when the dosing valve is closed.

According to a third aspect, the disclosure relates to a computer program comprising instructions to cause the arrangement of the first aspect, to execute the steps of the method according to the second aspect.

According to a fourth aspect, the disclosure relates to a computer-readable medium having stored thereon the computer program of the third aspect.

According to a fifth aspect, the disclosure relates to use of a standard diaphragm pump and a dosing valve for dosing cleaning agent into another fluid to obtain a target concentration of cleaning agent in the other fluid, and using the other fluid with the target concentration of cleaning agent for cleaning dairy flow lines. Brief description of the drawings

Fig. 1 illustrates an arrangement to be applied in dairy applications, for dosing cleaning agent into a fluid, according to a first embodiment.

Fig. 2 illustrates diagrams of the amount of fluid, and the corresponding opening time of the dosing valve and detected pump strokes.

Fig. 3 illustrates an arrangement for dairy applications, for dosing cleaning agent into a fluid, according to a second embodiment.

Fig. 4 illustrates a flow chart of a method for dosing cleaning agent into a fluid, according to some embodiments.

Detailed description

In the following disclosure, arrangements and methods for dosing cleaning agent into a fluid in dairy applications will be explained. The disclosure presents an arrangement using a diaphragm pump and a dosing valve for accurately dosing cleaning agent into another fluid, such as water. The arrangement provides a more accurate dosing solution compared to prior solutions using peristaltic pumps, as peristaltic pumps typically become more worn than diaphragm pumps. Also, there is no need to have a separate flow rate sensor to sense the flow rate of the cleaning agent, as the diaphragm pump has a known pump stroke volume. Flence, the flow rate or dosed volume of cleaning agent may be calculated based on the accomplished number of pump strokes and the pump stroke volume. As a flow rate sensor is obviated, the cost for the solution can be kept low, as a flow rate sensor is a rather expensive component. Also, as standard components can be used, the overall cost for the solution may be kept low.

The dosing arrangement is used for dosing cleaning agents into fluid that is used for cleaning fluid lines in dairy applications. A dairy application is for example a dairy system at a dairy farm, comprising pipelines that transfers milk from the animals to a cooling and storing tank. The milk may come from cows, goats or sheep. Another dairy application is the dairy system at a dairy plant, where the milk is refined to various products. In these industries, CIP systems are often used for cleaning the interior surfaces of the pipelines and vessels used for transporting and storing the dairy. The herein disclosed arrangement for dosing is thus used in such CIP system, for dosing cleaning agent in the fluid used for cleaning the interior surfaces. As previously described, the CIP system cleans the interior surfaces of the pipelines, vessels and associated things without dismantling. The cleaning involves circulating water and cleaning agent in the pipelines and vessels of the dairy system. The cleaning may be performed several times a day, and the dosing is typically performed on-line into water while the water is passed to the dairy application for cleaning, to avoid storing the ready-made cleaning solution.

Fig. 1 illustrates an arrangement 1 for dosing cleaning agent into a fluid, according to a first embodiment. The cleaning agent is for example detergent, sanitizer or disinfectant, or a mix thereof. The fluid is typically water but may be another liquid, for example a mixture of water and another agent. The arrangement 1 comprises a fluid circuit 31 , a diaphragm pump 3 and a dosing valve 5. The fluid circuit 31 typically comprises several fluid lines. More in detail, the fluid circuit 31 of Fig. 1 comprises a first fluid line 2 and a second fluid line 6. The first fluid line 2 fluidly connects a cleaning agent source 4 and the diaphragm pump 3. The first fluid line 2 is connected between an outlet of the cleaning agent source 4 and an inlet of the diaphragm pump 3. The second fluid line 6 connects the diaphragm pump 3 and a collection container 25. The second fluid line 6 is connected to an outlet of the diaphragm pump 3 and has an outlet directed to the collection container 25. The diaphragm pump 3 is arranged to provide a flow of cleaning agent in the fluid circuit 31 from the cleaning agent source 4. Thus, the diaphragm pump 3 withdraws cleaning agent from the cleaning agent source 4, via the first fluid line 2 into the diaphragm pump 3, via the inlet of the diaphragm pump 3. The diaphragm pump 3 also pumps the cleaning agent out from the diaphragm pump 3, via the outlet of the diaphragm pump 3, into the second fluid line 6. The dosing valve 5 is arranged to the fluid circuit 31 downstream the diaphragm pump 3. In more detail, the dosing valve 5 is arranged to the second fluid line 6. The dosing valve 5 is configured to regulate a dosage of cleaning agent from the diaphragm pump 3 to the collection container 25. Thus, the dosing valve 5 is openable such that a dosage of cleaning agent, pumped by the diaphragm pump 3, is passed to the collection container 25. The dosage of cleaning agent may be expressed as a flow rate or a volume. The dosing valve 5 is for example an on/off valve or a control valve.

An on/off valve is either fully open or fully closed. By regulating the opening time of the on/off valve, the dosage of cleaning agent may be controlled. The dosing valve 5 is typically opened for a period of time At for every X liter of water passed to the collection container 25.

A control valve controls the fluid flow rate by varying the size of the flow passage through the control valve. For example, the control valve may be regulated to provide a flow rate between 0-100% of a maximal flow rate through control valve. By regulating the opening degree of the control valve, the dosage of cleaning agent may be controlled. Thus, by using a dosing valve 5 being either an on/off valve or a control valve, the flow rate of cleaning agent may be regulated to provide a target concentration of cleaning agent in the water. Thus, the flow rate of the cleaning agent may be matched to the flow rate of the water. The dosing valve 5 is configured to be automatically controlled. The collection container 25 is for example a wash-trough.

In a preferred embodiment, the diaphragm pump 3 is a standard pump, that is designed for general industrial applications. The diaphragm pump 3 is for example an air driven diaphragm pump. In one embodiment, the diaphragm pump is the G- 57 series from Flojet^®. The diaphragm pump 3 comprises two pumping chambers that are alternatingly filled and discharged by the movement of flexible diaphragms. Compressed air is alternatingly fed to, and vented from, air chambers on the opposite sides of the diaphragms to create the pumping action.

A common drive shaft connects the two diaphragms. To get alternating pressure to the diaphragms, a changeover valve is built in and controlled by the position of the drive shaft. One pump stroke equal when the shaft goes from one side to the other. In the first embodiment in Fig. 1 , the diaphragm pump 3 is air driven. An air source 11, e.g. a source of compressed air, is illustrated as a circle. An inlet line 12 connects the air source 11 to an air inlet of the diaphragm pump 3. The inlet line 12 is thus connected between the air source 11 and the air inlet. A pressure regulated valve 13 makes sure the pressure in the inlet line 12 does not exceed a predetermined pressure. In other words, it functions as a pressure reducer, and sets the working pressure for the diaphragm pump 3. A control valve 14, e.g. a three-position valve, regulates the flow rate of air in the inlet line 12. An outlet line

15 connects the diaphragm pump 3 to an air outlet. The outlet may be directed out in the air or may be connected to an air collection source (not shown). A pump stroke sensor 16 is arranged to the outlet line 15. Thus, the pump stroke sensor

16 is external to the diaphragm pump 3. The pump stroke sensor 16 is configured to detect pump strokes of the diaphragm pump 3. In the first embodiment, the pump stroke sensor 16 is configured to detect when air is expelled from the diaphragm pump 3. The pump stroke sensor 16 is for example a pressure sensor. In other words, the pump stroke sensor 16 is a pressure sensor arranged to sense exhaust air from the diaphragm pump 3. A restrictor valve 17 may be arranged downstream the pump stroke sensor 16. Every time the diaphragm pump 3 makes a stroke, that is, when the drive shaft is reversed in its direction, it will relief air through its air outlet. The relieved air will be guided through the outlet line 15 and through the restrictor valve 17, whereby a pressure spike between the air outlet and the restrictor valve 17 will be sensed by the pump stroke sensor 16. The pump stroke sensor 16 will record the spike, whereby it is detected that the diaphragm pump 3 has given its stroke volume. The stroke volume is a known, constant volume. The stroke volume may be predetermined from the manufacturer. However, the stroke volume given from the manufacturer is not always reliable, as diaphragm pumps typically are not used for pumping a precise amount of fluid. Therefore, the stroke volume may be estimated by pumping a known volume with the diaphragm pump 3, while detecting the number of pump strokes needed to pump the whole volume. The stroke volume is estimated by dividing the pumped known volume with the number of detected pump strokes. The restrictor valve 17 may set by running the diaphragm pump 3 dry continuously. The restrictor valve 17 is manually adjusted during running. In alternative embodiments, the diaphragm pump 3 is driven with oil, gas or other kind of fluid. In still alternative embodiments, the diaphragm pump 3 is piston- driven. The pump stroke sensor 16 is then configured to detect the pump strokes in the alternative embodiment.

A source of fluid 9, in this example a water tap, is schematically illustrated with a circle. A water line 10 connects the source of fluid 9 and the collection container 25. The water line 10 is thus connected to the source of fluid 9, and has an outlet directed to the collection container 25. A water valve 8 is arranged to control a flow rate of water being passed to the collection container 25. The water valve is arranged to the water line 10. The water valve 8 is typically a control valve. A flow rate sensor 7 is arranged to measure the flow rate of the fluid in the water line 10. The flow rate sensor 7 is typically arranged to the water line 10 downstream the water valve 8. Thereby, the flow rate provided by the water valve 8 may be monitored such that a target fluid flow rate of water can be obtained. The volume of fluid, e.g. water, being passed to the collection container 25 is thus controlled by the water valve 8. The flow rate is for example a continuous flow of 1000-3000 ml/min. In one embodiment, the flow rate is 2000 ml/min. The volume of fluid being passed to the collection container 25 may alternatively be measured using a water height scale or a weight scale arranged to the collection container 25, or by any other suitable means.

Thus, the dosed cleaning agent and the other fluid, typically water, are collected in the collection container 25, and are mixed to a cleaning solution. The mixing may be performed by the inherit speeds of the fluids themselves or may be promoted by a separate mixing apparatus (not shown). The cleaning solution is guided to a dairy fluid circuit 32 in a dairy system 30 that is to be cleaned, via a connecting fluid circuit 26. The dairy system 30 is for example a system for transporting milk from animals to a tank for cooling and storing, or a system for processing milk.

The connecting fluid circuit 26 is arranged with a pump 27 and a cleaning solution valve 29. The pump 27 provides a cleaning solution flow from the collection container 25 into the dairy system 30. The cleaning solution valve 29 controls the flow rate of cleaning solution from the pump 27 to the dairy system 30. After the dairy system 30 has been cleaned, the used cleaning solution may be collected for reuse, or may be passed to a drain 33.

The arrangement 1 further comprises a control arrangement 20. The control arrangement 20 comprises processor 21 and memory 22. The control arrangement 20 typically also comprises a communication interface (not shown). The control arrangement 20 is for example a microcomputer, or a computer. The control arrangement 20 is typically locally arranged at the dairy system 30. The control arrangement 20 is configured to control the pumps 3, 27 and the valves 8, 14, 29 of the arrangement 1 , for example by sending control signals or control data to the pumps and valves. The control arrangement 20 is also configured to obtain data from the pumps 3, 27, the valves 8, 14, 29, the sensors 7, 16 etc., of the arrangement 1 , for example by receiving, reading or collecting sensed or detected properties of the same. For example, the control arrangement 20 may be configured to obtain a flow rate of fluid being passed to the collection container 25, typically from the flow rate sensor 7 itself. The control arrangement 20 may also be configured to calculate the volume of fluid being passed to the collection container 25, based on the flow rate of fluid being passed to the collection container 25. The control arrangement 20 may also comprise an operator interface (not shown), for example a touch screen or other suitable means, such that an operator may give input to the control arrangement 20. The operator may also be notified of the operation of the arrangement 1 via the operator interface.

In more detail, the control arrangement 20 is configured to control the dosing valve 5. The control arrangement 20 is configured to control the dosing valve 5 to regulate the dosage, such that a dosed volume of cleaning agent passed to the collection container 25 is correlated with a volume of fluid being passed to the collection container 25, in order to obtain a target concentration of cleaning agent in the fluid in the collection container 25. The dosage of cleaning agent from the dosing valve 5 is controlled by regulating the opening of the dosing valve 5. In other words, by controlling the flow rate or volume of the cleaning agent being passed to the collection container 25. The dosed volume of cleaning agent and the volume of fluid are being passed to the collection container 25 are passed to the collection container 25 during the same period of time. Thus, when the dosed volume of cleaning agent and the volume of fluid being passed to the collection container 25 are mixed, the resulting cleaning solution has obtained the target concentration of cleaning agent. It should be explicitly mentioned that the control arrangement 20 is not using a flow rate sensor for measuring a flow rate of dosed cleaning agent. In order to control the dosage valve 5, the control arrangement 20 is configured to send control data or control signals to the dosage valve 5.

Thus, the disclosure presents use of a standard diaphragm pump 3 and a dosing valve 5 for dosing cleaning agent into another fluid to obtain a target concentration of cleaning agent in the other fluid, and using the other fluid with the target concentration of cleaning agent for cleaning dairy flow lines.

In one embodiment, for each batch of volume of fluid, e.g. water, being passed to the collection container 25, a matching volume of cleaning agent is dosed into the collection container 25. For example, for each 2 liters of water being passed to the collection container 25, 10 ml of cleaning agent is dosed to the collection container 25 to create a 0.5 % concentration of detergent solution. Thus, by controlling the dosing valve 5 to dose at a rate that is correlated to the flow rate of the water passed to the collection container 25, the correct concentration can be achieved. In other words, the control arrangement 20 is configured to control the dosing valve 5 to an open state for a period of time correlated with a volume of fluid of a predetermined amount being passed to the collection container 25. In some embodiments, the dosed volume of cleaning agent passed to the collection container 25 is between 5 and 50 ml, and the volume of fluid being passed to the collection container 25 is between 1000 and 3000 ml, during the same time period. Typically, the operator also sets the flow rate of water by means of the water valve 8, by making an input to the control arrangement 20, via the operator interface. Thus, the flow rate of the water passed to the collection container 25 is known by the operator. The operator then sets the flow rate of the cleaning agent to a correlated dosage, by making an input to the control arrangement 20, defining the dosage, via the operator interface. If the dosage valve 5 is an on/off valve, the initial flow rate through the on/off valve when it is fully open is typically known. Thereby, by setting the opening time of the on/off valve, and when the on/off valve should open, the volume of cleaning agent can be controlled. For example, if the flow rate of water is set to 2 liters/minute, and the maximum flow rate through the dosage valve 5 is 100 ml/minute, the dosage valve 5 should be open for 6 seconds each minute to provide a dosage of 10 ml, and thereby provide a 0.5 % concentration of detergent solution in the collection container 25. If the dosage valve 5 is a control valve, and the maximum flow rate is 100 ml/minute, the control valve should be opened 10% all the time, to provide a dosage of 10 ml for each 2 liters of water.

The opening time of the dosage valve 5 may be changed to be able to dose a larger or smaller volume of cleaning agent, to provide a higher or lower concentration of cleaning agent in the cleaning solution, for example if using an on/off valve. In case of using a control valve, the opening degree may be changed to be able to dose a larger or smaller volume of cleaning agent, to provide a higher or lower concentration of cleaning agent in the cleaning solution.

As the pump stroke volume of the diaphragm pump 3 is known, it is known how much cleaning agent that has been dosed each time a pump stroke is detected. For example, if the pump stroke volume is 30 ml, then when a pumps stroke has been detected, it is known that 30 ml has been dosed since the previous pump stroke was detected. In other words, the control arrangement 20 is configured to estimate a current dosed volume of cleaning agent, dosed by the dosing valve 5, based on the information of the detected pump strokes and a predetermined pump stroke volume. Also, by detecting the pump strokes, the number of pump strokes may be calculated by counting the detected pump strokes. The number of pump strokes corresponds to the total dosed volume of cleaning agent. According to one embodiment, the estimated current dosed volume of cleaning agent is notified to an operator.

It should be understood that the speed of the diaphragm pump 3 is automatically changed in accordance with the opening of the dosing valve 5. For example, if the dosing valve 5 is closed, the diaphragm pump 3 cannot pump more fluid into the second fluid path 6 and it will halt its motion. In other words, the diaphragm pump 3 is halted when the dosing valve 5 is closed.

Even if the diaphragm pump 3 typically does not deteriorate to any greater extent with time, other components of the arrangement 1 may do so and the arrangement 1 may need to be calibrated such that a correct volume of cleaning agent is dosed. Also, components of the arrangement 1 such as valves do not always fulfill the specification from the manufacturer, specifically if cheaper, standard off-the shelf components are used, which is desired as the cost then may be reduced. Also for this reason the arrangement 1 may need to be calibrated. Fig. 2 illustrates diagrams of the amount of fluid, and the corresponding opening time of the dosing valve and detected pump strokes. The X-axis is illustrating a timeline in minutes, and the timeline is common for all the diagrams. The uppermost diagram illustrates with a rigid line the amount of fluid, e.g. water, that is passed to the collection container 25. About 18 liters are passed to the collection container 25 during the time period of 9 minutes. The lowermost diagram illustrates the corresponding detected pump strokes. Thus, after 3 minutes a pump stroke is detected. The pump stroke volume is for example 30 ml. The corresponding volume of water passed to the collection container 25 is 6 liters. Thus, a concentration of 0.5 % of cleaning agent is achieved (30 ml divided by 6000 ml). Thus, by comparing the pump strokes against the water volume passed to the collection container 25, the accuracy of the dosed cleaning agent can be determined. Also, if the dosed amount of cleaning agent is not accurate, the arrangement 1 may be automatically calibrated. Thus, the control arrangement 20 is configured to obtain information of the detected pump strokes from the dosing valve 5. This information is for example pressure sensor data indicative of a pressure spike, and thus a detected pump stroke. The control arrangement 20 is further configured to control the dosing valve 5 also based on information of the detected pump strokes. Thus, for each detected pump stroke, the amount of dosed cleaning agent may be compared to the amount of water passed to the collection container 25, during the same time period. If the target concentration of cleaning agent is not obtained, the amount of dosed cleaning agent should be changed.

The amount of dosed cleaning agent is changed by changing settings such as frequency of opening, length of time period At of the dosing valve 5, or opening degree of the dosing valve 5 in case of a control valve. A calibrated setting, that is, a frequency of opening, length of time period At or opening degree of the dosing valve 5, may be determined, such that the target concentration of cleaning agent is achieved. An error between the actual concentration and the target concentration of cleaning agent may be calculated. This error corresponds to an error between the actual dosage and the target dosage. In order to change one or several settings of the dosing valve 5 to remove the error, the result of the current settings of the dosing valve 5 may be determined. Thus, in some embodiments, the control arrangement 20 is configured to determine information indicative of a total opening time of the dosing valve 5 between the detected pump strokes. The information is for example the number of times the dosing valve 5 was open between the detected pump strokes, or the degree of opening of the dosing valve 5, in case the dosing valve 5 is a control valve. The control arrangement 20 may thus monitor how many times the dosage valve 5 is open during the detected pump strokes. The dosage valve 5 is typically open for a same time period At each time it opens. The total opening time is thus the number of times the dosage valve 5 is open, multiplied with the time period At. If there is an error between the actual concentration and the target concentration, the amount of cleaning agent passed to the collection container 25 should be changed. One or several of the settings of the dosage valve 5 are then changed, such that the dosed volume of cleaning agent corresponds to a target dosed volume needed to accomplish the target concentration of cleaning agent. In other words, the control arrangement 20 is configured to control the dosing valve 5 to regulate the dosage, based on the information indicative of a total opening time of the dosing valve 5 between the detected pump strokes and the correspondingly estimated dosed volume of cleaning agent during a same period of time, such that the target concentration of cleaning agent in the fluid in the collection container is obtained. An example is given in the middle diagram in Fig. 2. This diagram illustrates when the dosing valve 5, being an on/off valve, is open, during the same time period as in the other diagrams. When the first pump stroke is detected at 3 minutes, the dosing valve 5 has been opened three times during the same period of time. The dosing valve 5 is opened the same time period At each time the dosing valve 5 is opened. The dosing valve 5 is opened with a predetermined frequency. The frequency is for example correlated with the flow rate of the water passed to the collection container 25. The total opening time is thus three times At. Three times At is here equal to 30 ml of dosed cleaning agent. The dosed amount of cleaning agent is thus 30 ml per 6 liters of water. The dosed amount of cleaning agent is compared to a target amount of cleaning agent. If there is a difference between the dosed amount and the target amount, one or several settings of the dosing valve 5 is changed in order to provide an amount of dosed cleaning agent that it is equal to the target amount of cleaning agent needed to accomplish the target concentration in the cleaning solution. Thus, the control arrangement 20 may be configured to calculate one or several calibrated settings of the dosage valve 5, in order to provide an accurate concentration of cleaning agent, and to control the dosing valve 5 according to the calibrated one or several settings. The one or several settings of the dosing valve 5 are then configured according to the calibrated settings. For example, if the target concentration was 1% instead of 0.5%, the dosage should be 60 ml instead of 30 ml, per 6 liters of water. There is thus an error of 30 ml cleaning agent per 6 liters of water. This error may be corrected by, for example, changing the opening time At. To remove the error, the new calibrated opening time At_cai should be twice as large as the previous opening time. Previously, each opening time At dosed 10 ml of cleaning agent. Thus, with the new calibrated opening time, each opening time At_cai will dose 20 ml of cleaning agent. The control arrangement 20 then configures the settings of the dosing valve 5 according to the new calibrated opening time At_cai. Hence, if the amount of dosed cleaning agent is too small, the dosage is increased by increasing the frequency of opening, length of time period At or opening degree of the dosing valve 5. If the amount of dosed cleaning agent is too large, the dosage is decreased by decreased the frequency of opening, length of time period At or opening degree of the dosing valve 5. The control arrangement 20 may be configured to recalculate the one or several settings and to control the dosing valve 5 according to the new recalculated one or several settings at each new detected pump stroke, or at an interval of selected number of new detected pump strokes, such as every second, third, fourth or fifth etc. detected pump stroke. In some embodiments, the control arrangement 20 is configured to estimate a volume of cleaning agent that is missing in the cleaning solution because the dosing has been inaccurate, and to control the dosage valve 5 such that the estimated volume of cleaning agent is added to the fluid in the collection container 25.

Fig. 3 illustrates the arrangement 1 according to a second embodiment. In addition to what is illustrated in Fig. 1 , the arrangement 1 according to the second embodiment includes a plurality of dosing branches 35a, 35b for separately dosing several more cleaning agents into the cleaning container 25. It should be understood that the arrangement 1 according to the second embodiment is also used for dairy applications, but the application has in Fig. 3 been omitted for brevity. The cleaning agents are dosed one at a time. The dosing branches 35a, 35b have separate fluid lines but share the same air lines for operating the pumps and detecting pump strokes. The same references and parts as present in Fig. 1 will not be repeated here. Each of the first dosing branch 35a and the second dosing branch 35b comprises an additional diaphragm pump 3a, 3b arranged to provide a flow of cleaning agent in the fluid circuit 31 from an additional cleaning agent source 4a, 4b, and an additional dosing valve 5a, 5b arranged to the fluid circuit 31 downstream the additional diaphragm pump 3a, 3b. The additional dosing valve 5a, 5b is configured to regulate a dosage of cleaning agent from the additional diaphragm pump 3a, 3b to the collection container 25. The control arrangement 20 configured to control the additional dosing valve 5a, 5b to regulate the dosage, such that a dosed volume of cleaning agent passed to the collection container 25 is correlated with a volume of fluid being passed to the collection container 25, in order to obtain a target concentration of cleaning agent in the fluid in the collection container 25. In the first dosing branch, a fluid line 18 connects the inlet line 12 with an air inlet of the additional diaphragm pump 3a. An additional outlet line 19a connects the air outlet of the additional diaphragm pump 3a with the outlet path 15. An additional control valve 14a, e.g. a three-position valve, regulates the flow rate of air into the air inlet of the additional diaphragm pump 3a. The fluid circuit 31 comprises an additional first fluid line 2a and an additional second fluid line 6a. The additional first fluid line 2a connects the additional cleaning agent source 4a and the additional diaphragm pump 3a. The additional second fluid line 6a connects the additional diaphragm pump 3a and the collection container 25. The additional dosing valve 5a is arranged to the additional second fluid line 6a.

In the second dosing branch, the fluid line 18 connects the inlet line 12 with an air inlet of a further additional diaphragm pump 3b. A further additional outlet path 19b connects the air outlet of a further additional diaphragm pump 3b with the outlet line 15. A further additional control valve 14b, e.g. a three-position valve, regulates the flow rate of air into the air inlet of the further additional diaphragm pump 3b. The fluid circuit 31 comprises a further additional first fluid line 2b and a further additional second fluid line 6b. The further additional first fluid line 2b connects the further additional cleaning agent source 4b and the further additional diaphragm pump 3b. The further additional second fluid line 6b connects the further additional diaphragm pump 3b and the collection container 25. The further additional dosing valve 5b is arranged to the further additional second fluid line 6b.

The components of the first branch 35a and the second branch 35b have the same functions as the corresponding components of the arrangement according to Fig. 1. However, only one cleaning agent is dosed at a time. For example, when the cleaning agent from the additional cleaning agent source 4a is dosed, the control valves 14 and 14b are closed and the diaphragm pumps 3 and 3b are not operated. When the cleaning agent from the further additional cleaning agent source 4b is dosed, the control valves 14 and 14a are closed and the diaphragm pumps 3 and 3a are not operated. Thus, only one diaphragm pump at a time will be operated. Thereby it is avoided that different cleaning agents are mixed, and no (false) pulses are picked up by the pump stroke sensor 16 from other diaphragm pumps.

Fig. 4 illustrates a flow chart of a method for dosing cleaning agent into a fluid, according to some embodiments. The method may be implemented by the control arrangement 20 and saved into the memory 22 as computer instructions. When the computer instructions are executed by the processor 21 , the method will be performed by means of the arrangement 1 according to the first or the second embodiment. Thus, the memory 22 may store a computer program comprising instructions to cause the arrangement according to any one of the embodiments herein, to execute the steps of the method according to any one of the method steps herein. The disclosure also relates to a computer-readable medium having stored thereon the mentioned computer program. The computer-readable medium is for example a memory such as a flash-memory or an USB-memory (Universal Series Bus).

The method will now be explained with reference to the flow chart in Fig. 4, and with reference to the arrangement 1 according to the first or the second embodiment. The comprises providing S1, using a diaphragm pump 3, a flow of cleaning agent in a fluid circuit 31 from a cleaning agent source 4. The diaphragm pump 3 is thus pumping cleaning agent from the cleaning agent source 4. The method further comprises controlling S2 a dosing valve 5 to regulate a dosage of cleaning agent from the diaphragm pump 3 to a collection container 25, such that a dosed volume of cleaning agent passed to the collection container 25 is correlated with a volume of fluid being passed to the collection container 25, in order to obtain a target concentration of cleaning agent in the fluid in the collection container 25. For example, the flow rate of the fluid, e.g. water, is known in beforehand, and the method comprises controlling the dosing valve 5 to a flow rate that matches the flow rate of the water, such that the target concentration is obtained. Typically, the dosing valve 5 is opened for a set time for each X litre of water. As should be understood, the dosed volume of cleaning agent and the volume of fluid being passed to the collection container 25 are passed to the collection container 25 during the same period of time. It should also be understood that the controlling S2 comprises halting the diaphragm pump 3 when the dosing valve 5 is closed. In other words, the diaphragm pump 3 is automatically halted as it cannot push more cleaning agent to the dosing valve 5, as it is closed.

In some embodiments, the method comprises detecting S3 pump strokes of the diaphragm pump 3. For example, the detection S3 comprises detecting the pump strokes by means of the pump stroke sensor 16. In case the diaphragm pump 3 is air driven, the pump strokes may give rise to a pressure spike that can be detected by a pressure sensor or similar. Each pump stroke will indicate that a predetermined pump stroke volume of cleaning agent has been dosed to the collection container 25 (except the first pump stroke after starting the diaphragm pump 3). In these embodiments, the controlling S2 comprises controlling the dosing valve 5 also based on information of the detected pump strokes. Thus, by comparing the volume of dosed cleaning agent to the volume of water passed to the collection container 25, the correctness of the concentration of cleaning agent may be established, and the volume of dosed cleaning agent corrected, if needed. The volume of dosed cleaning agent may be estimated. For example, the method comprises estimating S4 a current volume of dosed cleaning agent based on the information of the detected pump strokes and a predetermined pump stroke volume.

Because of pump drive pressure and/or increased resistance in the fluid circuit, in some embodiments, the dosed volume of cleaning agent may no longer correspond to the target dose of cleaning agent necessary for obtaining a target concentration of cleaning agent in the fluid in the collection container 25. The volume to be dosed may then advantageously be automatically adjusted and changed such that it corresponds to the target dose of cleaning agent. By obtaining information of when the dosing valve 5 is open between two pump strokes, and the time period it is open At each time, the total opening time of the dosing valve 5 between two pump strokes may be determined. The total opening time between two pump strokes thus corresponds to a predetermined stroke volume. It can then be calculated how much the opening time or frequency of opening of the dosing valve 5 should be changed, in order to provide the target dosage during the same time period, such that the target concentration of cleaning agent can be achieved. In other words, the method comprises determining S5 information indicative of a total opening time of the dosing valve 5 between the detected pump strokes. The method further comprises controlling S2 the dosing valve 5 to regulate the dosage, based on the information indicative of the total opening time of the dosing valve 5 between the detected pump strokes and the correspondingly estimated current dosed volume of cleaning agent during a same period of time, such that the target concentration of cleaning agent in the fluid in the collection container is obtained. In some embodiments, the valve opening is automatically corrected for the water flow, by an X litre batch synchronisation. The valve opening time At is used to correct the dosed volume per opening so it meets the target volume needed in every X litre of water. Thus, it can be assured that a good concentration is dosed. The method may thus comprise recalculating the opening time for the dosing valve 5, so the dosing valve 5 lets in the volume of cleaning agent matching the added volume of water, and control the dosing valve based on the recalculated opening time.

The present disclosure is not limited to the above-described preferred embodiments. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiments should not be taken as limiting the scope of the disclosure, which is defined by the appending claims.

Claims

1. An arrangement (1 ) for dairy applications, for dosing cleaning agent into a fluid, the arrangement (1) comprises:

- a fluid circuit (31);

- a diaphragm pump (3) arranged to provide a flow of cleaning agent in the fluid circuit (31) from a cleaning agent source (4);

- a dosing valve (5) arranged to the fluid circuit (31 ) downstream the diaphragm pump (3), wherein the dosing valve (5) is configured to regulate a dosage of cleaning agent from the diaphragm pump (3) to a collection container (25);

- a control arrangement (20) configured to control the dosing valve (5) to regulate the dosage, such that a dosed volume of cleaning agent passed to the collection container (25) is correlated with a volume of fluid being passed to the collection container (25), in order to obtain a target concentration of cleaning agent in the fluid in the collection container (25).

2. The arrangement (1 ) according to claim 1 , wherein the dosed volume of cleaning agent and the volume of fluid being passed to the collection container

(25) are passed to the collection container (25) during the same period of time.

3. The arrangement (1 ) according to claim 1 or 2, comprising:

- a pump stroke sensor (16) configured to detect pump strokes of the diaphragm pump (3), and wherein the control arrangement (20) is configured to:

- obtain information of the detected pump strokes; and to

- control the dosing valve (5) also based on information of the detected pump strokes.

4. The arrangement (1 ) according to claim 3, wherein the control arrangement

(20) is configured to: - estimate a current dosed volume of cleaning agent, dosed by the dosing valve (5), based on the information of the detected pump strokes and a predetermined pump stroke volume.

5. The arrangement (1 ) according to claim 4, wherein the control arrangement (20) is configured to:

- determine information indicative of a total opening time of the dosing valve (5) between the detected pump strokes; and

- control the dosing valve (5) to regulate the dosage, based on the information indicative of a total opening time of the dosing valve (5) between the detected pump strokes and the correspondingly estimated dosed volume of cleaning agent during a same period of time, such that the target concentration of cleaning agent in the fluid in the collection container is obtained.

6. The arrangement (1 ) according to any one of the claims 3 to 5, wherein the diaphragm pump (3) is air driven, and the pump stroke sensor is a pressure sensor arranged to sense exhaust air from the diaphragm pump (3).

7. The arrangement (1 ) according to any one of the claims 3 to 6, wherein the pump stroke sensor is external to the diaphragm pump (3).

8. The arrangement (1 ) according to any one of the preceding claims, wherein the dosing valve (5) is an on/off valve or a control valve.

9. The arrangement (1 ) according to any one of the preceding claims, wherein the diaphragm pump (3) is halted when the dosing valve (5) is closed.

10. The arrangement (1) according to any one of the preceding claims, wherein the control arrangement (20) is configured to control the dosing valve (5) to an open state for a period of time correlated with a volume of fluid of a predetermined amount being passed to the collection container (25).

11 . The arrangement (1 ) according to any one of the preceding claims, wherein the control arrangement (20) is configured to obtain a flow rate of fluid being passed to the collection container (25).

12. The arrangement (1 ) according to claim 11 , wherein the control arrangement (20) is configured to calculate the volume of fluid being passed to the collection container (25), based on the flow rate of fluid being passed to the collection container (25).

13. The arrangement (1 ) according to any one of the preceding claims, wherein the control arrangement (20) is not using a flow rate sensor for measuring a flow rate of dosed cleaning agent.

14. The arrangement (1 ) according to any one of the preceding claims, comprising one or several dosing branches comprising: an additional diaphragm pump (3a, 3b) arranged to provide a flow of cleaning agent in the fluid circuit (31 ) from an additional cleaning agent source (4a, 4b); an additional dosing valve (5a, 5b) arranged to the flow circuit (31 ) downstream the additional diaphragm pump (3a, 3b), wherein the additional dosing valve (5a, 5b) is configured to regulate a dosage of cleaning agent from the additional diaphragm pump (3a, 4b) to the collection container (25).

15. The arrangement according to any one of the preceding claims, wherein the dosed volume of cleaning agent passed to the collection container (25) is between 5 and 50 ml, and the volume of fluid being passed to the collection container (25) is between 1000 and 3000 ml.

16. A method for dosing cleaning agent into a fluid, the method comprises

- providing (S1 ), using a diaphragm pump (3), a flow of cleaning agent in a fluid circuit (31 ) from a cleaning agent source (4);

- controlling (S2) a dosing valve (5) to regulate a dosage of cleaning agent from the diaphragm pump (3) to a collection container (25), such that a dosed volume of cleaning agent passed to the collection container (25) is correlated with a volume of fluid being passed to the collection container (25), in order to obtain a target concentration of cleaning agent in the fluid in the collection container (25).

17. The method according to claim 16, wherein the dosed volume of cleaning agent and the volume of fluid being passed to the collection container (25) are passed to the collection container (25) during the same period of time.

18. The method according to claim 16 or 17, comprising:

- detecting (S3) pump strokes of the diaphragm pump (3); and

- controlling (S2) the dosing valve (5) also based on information of the detected pump strokes.

19. The method according to claim 18, comprising:

- estimating (S4) a current volume of dosed cleaning agent based on the information of the detected pump strokes and a predetermined pump stroke volume.

20. The method according to claim 19, comprising:

- determining (S5) information indicative of a total opening time of the dosing valve (5) between the detected pump strokes; and

- controlling (S2) the dosing valve (5) to regulate the dosage, based on the information indicative of the total opening time of the dosing valve (5) between the detected pump strokes and the correspondingly estimated current dosed volume of cleaning agent during a same period of time, such that the target concentration of cleaning agent in the fluid in the collection container is obtained.

21. The method according to any one of the claims 12 to 16, wherein the controlling (S2) comprises halting the diaphragm pump (3) when the dosing valve (5) is closed.

22. A computer program comprising instructions to cause the arrangement of any one of the claims 1 to 15, to execute the steps of the method according to any one of the claims 16 to 21.

23. A computer-readable medium having stored thereon the computer program of claim 22.

24. Use of a standard diaphragm pump and a dosing valve for dosing cleaning agent into another fluid to obtain a target concentration of cleaning agent in the another fluid, and using the another fluid with the target concentration of cleaning agent for cleaning dairy flow lines.