Background

Mixing of fluids is required in several applications. For example, in order to clean glass panels of greenhouses, a mixture of calcium carbonate and water may be required. In this case, calcium carbonate may be provided in the form of a liquid with calcium carbonate either dissolved or suspended in the liquid. Accordingly, the liquid may be mixed with water in order to obtain a mixture having a desired consistency. In such cases, it may be important to maintain a desired ratio of the liquid to the water. Therefore, a flow meter for measuring the quantity of the liquid and the quantity of water supplied to obtain the mixture may be used. Further, based on one or more of the quantity of the liquid and the quantity of water, a flow of one or more of the liquid and the water may be controlled. However, in cases where the liquid has high viscosity, it becomes difficult to measure a flow of the liquid. Moreover, in cases where the liquid comprises microscopic particles, a flow meter used to measure a flow of the liquid may be subjected to wear due to the microscopic particles. Accordingly, there is a need for improved methods and apparatus for mixing two or more fluids where it may not be preferable to measure a flow of at least one fluid of the two or more fluids.

Summary Disclosed herein is a method of mixing fluids. The method includes mixing a plurality of fluids in a first mixing (104) unit to obtain an intermediate mixture. Further, the method includes mixing at least one fluid of the plurality of fluids with the intermediate mixture in a second mixing unit (112) to obtain a final mixture. Additionally, the method includes calculating a flow rate of at least one fluid of the plurality of fluids based on each of a flow rate of the final mixture and a flow rate of at least one other fluid of the plurality of fluids to obtain a calculated flow rate. Accordingly, in an embodiment, the flow rate of the final mixture may be measured by a mixture flow meter (116). Further, the flow rate of the at least one other fluid of the plurality of fluids may be measured by at least one flow meter (120). Moreover, in an embodiment, the calculating may be performed by a Programmable Logic Controller (PLC).

In an embodiment, a viscosity of the at least one fluid corresponding to the calculated flow rate may be at least 7800 Centipoises at a

temperature of 17.9 degrees Celsius.

In an embodiment, the at least one fluid corresponding to the flow rate may comprise calcium carbonate. Further, the at least one other fluid may be water.

In an embodiment, the first mixing unit (104) may be a venturi injector (306). Further, the second mixing unit (116) may be a static mixing unit (310)

In an embodiment, the calculating may include subtracting the flow rate of the at least one other fluid of the plurality of fluids from the flow rate of the final mixture. In an embodiment, the method may further include controlling a flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit (112) based on each of the calculated flow rate and a predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture. In an embodiment, the controlling may be performed

automatically by the PLC. Further disclosed herein is an apparatus (100) for mixing fluids. The apparatus (100) includes a first mixing unit (104) configured for mixing a plurality of fluids to obtain an intermediate mixture. The apparatus further includes a second mixing unit (112) configured for mixing at least one fluid of the plurality of fluids with the intermediate mixture to obtain a final mixture. Furthermore, the apparatus (100) includes a Programmable Logic Controller (PLC) for calculating a flow rate of at least one fluid of the plurality of fluids based on each of a flow rate of the final mixture and a flow rate of at least one other fluid of the plurality of fluids to obtain a calculated flow rate. Additionally, the apparatus (100) may include a mixture flow meter (116) configured for measuring the flow rate of the final mixture. Further, the apparatus (100) may include at least one flow meter (120) configured for measuring the flow rate of at least one other fluid of the plurality of fluids.

In an embodiment, a viscosity of the at least one fluid corresponding to the calculated flow rate may be at least 7800 Centipoises at a

temperature of 17.9 degrees Celsius. In an embodiment, the PLC may be configured for subtracting the flow rate of the at least one other fluid of the plurality of fluids from the flow rate of the final mixture.

In an embodiment, the at least one fluid corresponding to the flow rate may comprise calcium carbonate. Further, the at least one other fluid may be water.

In an embodiment, the first mixing unit (104) may be a venturi injector (306). Additionally, the second mixing unit (112) may be a static mixing unit (320). In an embodiment, the first mixing unit (104) may be located in a vicinity of a tank (102) of at least one fluid of the plurality of fluids.

In an embodiment, the apparatus may further include at least one valve (114) configured for controlling a flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit (112) based on each of the calculated flow rate and a predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture. In an embodiment, the PLC may be configured for automatically controlling the flow rate of at least one fluid of the plurality of fluids.

Brief description of drawings FIG. 1 illustrates an apparatus for mixing a plurality of fluids in accordance with an embodiment.

FIG. 2 illustrates a flow chart of a method of mixing a plurality of fluids in accordance with an embodiment.

FIG. 3 illustrates an apparatus for mixing a plurality of fluids in accordance with an exemplary embodiment.

Detailed description

FIG. 1 illustrates an apparatus 100 for mixing a plurality of fluids in accordance with an embodiment disclosed herein. The plurality of fluids may be one or more of a liquid, a gas and a slurry. Each fluid of the plurality of fluids may be stored in at least one tank 102. For example, as illustrated, tanks 102a, 102b and 102c may store the plurality of fluids. The apparatus 100 includes a first mixing unit 104 configured for mixing the plurality of fluids to obtain an intermediate mixture. The first mixing unit 104 may be one or more of, but not limited to, a venturi injector, a mixing tee, a sparger, a swirl mixer, a static mixer, a dynamic mixer, an educator, a siphon, a rotary mixer and an agitator. In an embodiment, the first mixing unit 104 may be configured for creating a low pressure in at least one inlet port of the first mixing unit 104. Accordingly, the low pressure may cause the at least one fluid of the plurality of fluids to flow into the first mixing unit 104 through the at least one inlet port. In an embodiment, the first mixing unit 104 may be a venturi injector. In an embodiment, the first mixing unit 104 may be further configured for stirring the plurality of fluids. As a result, homogeneity of the intermediate mixture may be improved.

Further, in an embodiment, the first mixing unit 104 may be located in a vicinity of a tank of at least one fluid of the plurality of fluids.

Consequently, a path leading out from the at least one fluid of the plurality of fluids to the first mixing unit 104 may be of relatively short in length. Such an embodiment may be suitable in cases where the at least one fluid may be highly viscous. The flow rate performance caused by the venture injector depends on the viscosity of the fluid, the width of the path, and, surprisingly, by the length of the path. To keep the flow rate substantially constant in speed, the length of the path shall be limited up to a maximum length which is equal to 1 ,25 times the cross sectional area of the path, causing an excellent performance in supplying the fluid from the tank 102a through the first mixing unit 104 towards the tank 118. In this way, even a fluid to be conveyed comprising microscopic particles and having a high viscosity, may be pumped by a rather constant flow causing a reliable way to measure the flow rate of the fluid. In case of the fluid is calcium carbonate to be applied on glass panels of greenhouses to set the permeability of light, the flow rate of the fluid may be measured in an accurate way. Accordingly, in an embodiment, at least one hose 106 may be used to carry at least one fluid of the plurality of fluids to the first mixing unit 104. Additionally, in an embodiment, the apparatus 100 may further include a pump 108 configured for pumping at least one fluid of the plurality of fluids. The pumping may cause a forced flow of the at least one fluid. Although FIG. 1 illustrates the pump 108 configured for pumping fluid from the tank 102a, it should be understood that the pump 108 in other embodiments may be configured for pumping fluid from any tank of the at least tank 102. For example, the pump 108 be situated on a path leading out from any tank of the at least one tank 102, such as for example, tank 102b or tank 102c.

Further, the apparatus 100 may include at least one valve 110 along a path leading out of the at least one tank 102. For example, as illustrated, valves 110a, 110b and 110c may be situated at a path leading out of each of tanks 102a, 102b and 102c respectively. In an embodiment, the at least one valve 110 may ensure a unidirectional flow of fluid out of the at least one tank 102. For example, the valve 110b may be configured for allowing flow of fluid from the tank 102b into the first mixing unit 104. However, the valve 110b may prevent a flow of fluid from the first mixing unit 104 into the tank 102b. Further, in another embodiment, the at least one valve 110 may be adjustable to control a rate of flow of fluid within the at least one valve 110. Although FIG. 1 illustrates the at least one valve 110 situated along a path leading from each of tank the 102a, the tank 102b and the tank 102c, it should be understood that in other embodiments, the at least one valve 110 may not be present along a path leading from a tank of the at least one tank 102 to the first mixing unit 104. In an embodiment, at least one fluid of the plurality of fluids may comprise solid particles. In an embodiment, an average size of the solid particles may be in the range of 1 to 1000 m. Further, in an embodiment, the solid particles may be abrasive. In an embodiment, the solid particles may be composed of one or more of metal, silica and calcium carbonate. In an embodiment, the at least one fluid may comprise microscopic glass particles. In an embodiment, at least one fluid of the plurality of fluids may be a colloid. In an embodiment, at least one fluid of the plurality of fluids may be a high viscosity fluid. In an embodiment, a viscosity of the at least one fluid may be equal to or greater than 2000 Centipoises at a temperature range of -25°C to 75°C. In an embodiment, a viscosity of at least one fluid of the plurality of fluids may be equal to or greater than 7800 Centipoises at a temperature of 17.9°C. In an embodiment, at least one fluid of the plurality of fluids may be in a form of gel. In an embodiment, the at least one fluid of the plurality of fluids may be one or more of a liquid, a gas and a slurry.

In an embodiment, a viscosity of at least one fluid of the plurality of fluids may be substantially higher than a viscosity of at least one other fluid of the plurality of fluids. In an embodiment, a concentration of solid particles in at least one fluid of the plurality of fluids may be substantially higher than a concentration of solid particles in at least one other fluid of the plurality of fluids. In an embodiment, the at least one fluid may comprise calcium carbonate. In an embodiment, the at least one other fluid may be an aqueous solution. Further, in an embodiment, the at least one other fluid may be water.

In an embodiment, at least one fluid of the plurality of fluids may include fibres. In an embodiment, the fibres may be dissolved in the at least one fluid. In an embodiment, an average length of the fibres may be in the range of 200 to 2000 m. In an embodiment, an average width of the fibres may be in the range of 10 to 50 pm. In an embodiment, the fibres comprise wooden fibres to form the at least one fluid into papier-mache.

In an embodiment, the plurality of fluids may consist of a first fluid and a second fluid. Further, a value of a property of the first fluid may be different from a value of the property of the second fluid. In an

embodiment, the property may be one or more of viscosity, boiling point, freezing point, specific heat capacity, surface tension, density, specific gravity, and a concentration of one or more chemical substances therein. Accordingly, in an example, a viscosity of the first fluid may be

substantially lower in value than a viscosity of the second fluid. In an embodiment, the one or more chemical substances may be dissolved in at least one of the first fluid and the second fluid. In an embodiment, a concentration of solid particles in the first fluid may be substantially lower than a concentration of solid particles in the second fluid. In an embodiment, the apparatus 100 further includes a second mixing unit 112 configured for mixing at least one fluid of the plurality of fluids with the intermediate mixture to obtain a final mixture. The second mixing unit 112 may be one or more of, but not limited to, a mixing tee, a sparger, a swirl mixer, a static mixer, a dynamic mixer, a rotary mixer and an agitator. In an embodiment, the apparatus 100 may further include a third mixing unit (not shown in figure) configured for stirring the intermediate mixture flowing out of the first mixing unit 104. In an embodiment, the third mixing unit may be one or more of a static mixer and a dynamic mixer. Further,

in an embodiment, the apparatus 100 may further include a stirrer (not shown in figure) configured for stirring one or more fluids of the at least one fluid of the plurality of fluids and the intermediate mixture.

Accordingly, homogeneity of the intermediate mixture may be improved. Additionally, in an embodiment, the apparatus 100 may further include a fourth mixing unit (not shown in figure) configured for stirring the final mixture. In an embodiment, fourth mixing unit may be at least one of a static mixer and a dynamic mixer. Accordingly, homogeneity of the final mixture may be improved. In an instance, improving homogeneity of the final mixture may enable measurement of a flow rate of the final mixture to be performed more accurately. Further, the apparatus 100 may include at least one adjustable valve 114 configured for controlling flow of at least one fluid of the plurality of fluids into the second mixing unit 112. Further, at least one path may be included in the apparatus 100 for carrying the at least one fluid from the at least one tank 102 to the second mixing unit 112. In an embodiment, the at least one adjustable valve 114 may be configured for being adjusted manually. In another embodiment, the at least one adjustable valve 114 may be coupled to an electric actuator for being adjusted automatically. Although FIG. 1 illustrates the second mixing unit 112 configured for receiving each of the intermediate mixture and the fluid from tank 102a, it should be understood that in other embodiments, the second mixing unit 112 may be configured for receiving fluid from any tank of the at least one tank 102, such as for example, the tank 102b or the tank 102c.

The apparatus 100 may further include at least one mixture flow meter 116 for measuring a flow rate of the final mixture flowing out of the second mixing unit 112. In an embodiment, the final mixture may be collected in a tank 118.

Additionally, in an embodiment, the apparatus 100 may include a

Programmable Logic Controller (PLC) (not shown in the figure) configured for calculating a flow rate of at least one fluid of the plurality of fluids based on each of a flow rate of the final mixture and a flow rate of at least one other fluid of the plurality of fluids to obtain a calculated flow rate. Accordingly, the apparatus 100 may include at least one flow meter 120 for measuring a flow rate of the at least one other fluid of the plurality of fluids. In an embodiment, the PLC may be implemented in one or more of hardware and software. Examples of the PLC include, but are not limited to, a microprocessor, microcontroller, a Field Programmable Gate Array (FPGA) and an Application Specific Integrated Circuit (ASIC). In an embodiment, the at least one fluid corresponding to the calculated flow rate may comprise solid particles. In an embodiment, an average size of the solid particles may be in the range of 1 to 1000 Mm. Further, in an embodiment, the solid particles may be abrasive. In an embodiment, the solid particles may be composed of one or more of metal, silica and calcium carbonate. In an embodiment, the at least one fluid

corresponding to the calculated flow rate may comprise microscopic glass particles. Accordingly, it may not be suitable to measure the flow rate of the at least one fluid corresponding to the calculated flow rate due to wear on a flow meter.

In an embodiment, the at least one fluid corresponding to the calculated flow rate may be a colloid. In an embodiment, the at least one fluid corresponding to the calculated flow rate may be a high viscosity fluid. In an embodiment, a viscosity of the at least one fluid may be equal to or greater than 2000 Centipoises at a temperature range of -25°C to 75°C. In an embodiment, a viscosity of the at least one fluid corresponding to the calculated flow rate may be equal to or greater than 7800 Centipoises at a temperature of 17.9°C. In an embodiment, the at least one fluid may be in a form of gel. Accordingly, it may not be suitable to measure the flow rate of the at least one fluid corresponding to the calculated flow rate due to technical difficulties. In an embodiment, the at least one fluid corresponding to the calculated flow rate may be one or more of a liquid, a gas and a slurry.

In an embodiment, a viscosity of the at least one fluid corresponding to the calculated flow rate may be substantially higher than a viscosity of at least one other fluid of the plurality of fluids. In an embodiment, a concentration of solid particles in the at least one fluid corresponding to the calculated flow rate may be substantially higher than a concentration of solid particles in at least one other fluid of the plurality of fluids. In an embodiment, at least one fluid corresponding to the calculated flow rate may include fibres. In an embodiment, the fibres may be dissolved in the at least one fluid. In an embodiment, an average length of the fibres may be in the range of 200 to 2000 pm. In an embodiment, an average width of the fibres may be in the range of 10 to 50 pm.

In an embodiment, the PLC may be configured for calculating a flow rate corresponding to each of at least two fluids of the plurality of fluids.

Accordingly, in an embodiment, a relationship between a flow rate corresponding to each fluid of the at least two fluids and at least one other fluid of the at least two fluids may be predetermined. For example, in an embodiment, each of the valve 110b and the valve 110c may be ganged together. Further, each of the valve 110b and valve 110c may be configured such that a ratio of flow rate of fluid flowing through valve 110b to flow rate of fluid passing through valve 110c may be

predetermined. In another embodiment, a flow rate corresponding to each fluid of the at least two fluids may be expressible as a function of a flow rate of at least one other fluid of the at least two fluids. For example, the flow rate of fluid passing through valve 110b may be a function of the flow rate of fluid passing through valve 110c. In an embodiment, the function may be a linear function. In yet another embodiment, a flow rate corresponding to each fluid of the at least two fluids may be a multiple of a flow rate of at least one other fluid of the at least two fluids. For example, the flow rate of fluid passing through valve 110b may be twice the flow rate of fluid passing through valve 110c.

In an embodiment, the PLC may be configured for subtracting the flow rate of the at least one other fluid of the plurality of fluids from the flow rate of the final mixture. In another embodiment, the PLC may be configured for calculating a flow rate corresponding to each of at least two fluids of the plurality of fluids by solving an underdetermined linear equation. For instance, the underdetermined equation may be the equation expressing the flow rate of the final mixture in terms of flow rate of each of the plurality of fluids. For example, it may not be suitable to measure flow rate of fluids leading out of each of the tank 102b and the tank 102c. Accordingly, the number of unknown variables may be two but the number of equations may be one, resulting in the underdetermined equation. Further, a flow rate of each fluid of the at least two fluids of the plurality of fluids may be constrained by each of an upper limit and a lower limit. Accordingly, a solution space of the underdetermined equation may be restricted by each of the upper limit and the lower limit. In an embodiment, the PLC may be configured for solving the

underdetermined linear equation based on linear programming.

In an embodiment, the at least one valve 110 may be configured for controlling a flow rate of the at least one other fluid of the plurality of fluids based on each of the calculated flow rate and a predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture. However, in an embodiment, the at least one valve 110 may be configured to be adjusted manually by an operator. The operator may adjust the at least one valve 110 based on each of the calculated flow rate and a predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture.

In another embodiment, the at least one valve 114 may be configured for controlling a flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit 112 based on each of the calculated flow rate and a predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture. In an embodiment, at least one of the at least one valve 110 and the at least one valve 114 may be coupled to at least one actuator. Further, the at least one actuator may be configured for being controlled by the PLC. However, in an embodiment, the at least one valve 114 may be configured to be adjusted manually by an operator. The operator may adjust the at least one valve 114 based on each of the calculated flow rate and a predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture.

In an embodiment, the apparatus 100 may further include a display device (not shown in figure) configured for displaying at least one of the flow rate of the final mixture, the calculated flow rate of at least one fluid of the plurality of fluids and the flow rate of the at least one other fluid of the plurality of fluids. In an embodiment, the PLC may be further configured for computing a proportionality relationship among the plurality of fluids based on each of the flow rate of the final mixture, the calculated flow rate of at least one fluid of the plurality of fluids and flow rate of the at least one other fluid of the plurality of fluids. Further, in an embodiment, the display device may be configured for displaying the proportionality relationship.

Additionally, in an embodiment, the apparatus 100 may include a transmitting unit (not shown in figure) configured for transmitting at least one of the flow rate of the final mixture, the calculated flow rate of at least one fluid of the plurality of fluids, the flow rate of the at least one other fluid of the plurality of fluids and the proportionality relationship to a remote device. Accordingly, an input unit of the remote device may be configured for receiving a command. The command may be received, for example, from an operator. The remote device may further include a transmitting unit configured for transmitting the command from the remote device to the PLC. Further, the PLC may be further configured for executing the command. Moreover, executing the command may control at least one of a flow rate of the at least one other fluid of the plurality of fluids and a flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit 112. In an instance, executing the command may cause at least one of a flow rate of the at least one other fluid of the plurality of fluids and a flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit 112 to increase by at least one of a predetermined magnitude and an operator specified magnitude. In another instance, executing the command may cause at least one of a flow rate of the at least one other fluid of the plurality of fluids and a flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit 112 to decrease by at least one of a predetermined

magnitude and an operator specified magnitude.

Additionally, in an embodiment, the PLC may be further configured for generating an alarm based on each of the calculated flow rate and a predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture.

In another embodiment, the PLC may be further configured for determining a volume of at least one fluid of the plurality of fluids consumed from the at least one tank 102 during a time period during which the mixing of the plurality of fluids may be performed. The PLC may further be configured for determining a volume of the final mixture generated during the time period. Further, the apparatus 100 may include a printer configured for printing at least one of the volume of the at least one fluid and the volume of the final mixture.

FIG. 2 illustrates a method of mixing the plurality of fluids in accordance with an embodiment. The plurality of fluids may be one or more of a liquid, a gas and a slurry. At step 202, the plurality of fluids may be mixed in the first mixing unit 104 to obtain the intermediate mixture. Each fluid of the plurality of fluids may be stored in the at least one tank 102. For example, as illustrated, tanks 102a, 102b and 102c may store the plurality of fluids. The first mixing unit 104 may be one or more of, but not limited to, a venturi injector, a mixing tee, a sparger, a swirl mixer, a static mixer, a dynamic mixer, an educator, a siphon, a rotary mixer and an agitator. In an embodiment, the first mixing unit 104 may be configured for creating a low pressure in at least one inlet port of the first mixing unit 104. Accordingly, the low pressure may cause the at least one fluid of the plurality of fluids to flow into the first mixing unit 104 through the at least one inlet port. In an embodiment, the first mixing unit 104 may be a venturi injector. In another embodiment, the method may further include stirring the plurality of fluids in the first mixing unit 104.

Further, in an embodiment, the method may include placing the first mixing unit 104 at a location in a vicinity of a tank of the at least one fluid of the plurality of fluids. Accordingly, in an embodiment, the at least one hose 106 may be used to carry the at least one fluid of the plurality of fluids to the first mixing unit 104. Additionally, in an embodiment, the method may further include pumping the at least one fluid of the plurality of fluids by means of the pump 108. The pumping may cause a forced flow of the at least one fluid.

Further, in an embodiment, the method may include controlling a flow of fluid along a path leading out of the at least one tank 102 by means of the at least one valve 110. For example, as illustrated in FIG. 1 , valves 110a, 110b and 110c may be situated at a path leading out of each of tanks 102a, 102b and 102c respectively. In an embodiment, the at least one valve 110 may ensure a unidirectional flow of fluid out of the at least one tank 102. Further, in another embodiment, the method may further include controlling a rate of flow of fluid passing through the at least one valve 110. Accordingly, the at least one valve 110 may be adjustable to control the rate of flow.

Details regarding the at least one fluid of the plurality of fluids are provided in conjunction with FIG. 1.

Subsequently, at step 204, the at least one fluid of the plurality of fluids may be mixed with the intermediate mixture in the second mixing unit 112 to obtain the final mixture. The second mixing unit 112 may be one or more of, but not limited to, a mixing tee, a sparger, a swirl mixer, a static mixer, a dynamic mixer, a rotary mixer and an agitator. In an

embodiment, the method may further include stirring the intermediate mixture flowing out of the first mixing unit 104 by means of the third mixing unit. In an embodiment, the third mixing unit may be one or more of a static mixer and a dynamic mixer. Furthermore, in an embodiment, the method may further include stirring one or more fluids of the at least one fluid of the plurality of fluids and the intermediate mixture by means of the stirrer. Additionally, in an embodiment, the method may further include stirring the final mixture by means of the fourth mixing unit. In an embodiment, fourth mixing unit may be one or more of a static mixer and a dynamic mixer. Further, the method may include controlling flow of at least one fluid of the plurality of fluids into the second mixing unit 112 by means of the at least one adjustable valve 114. In an embodiment, the method may further include manually adjusting the at least one adjustable valve 114. In another embodiment, the method may include automatically adjusting the at least one adjustable valve 114 by means of the electric actuator coupled to the at least one adjustable valve 114.

Furthermore, in an embodiment, the method may include measuring the flow rate of the final mixture flowing out of the second mixing unit 112 by means of the at least one mixture flow meter 116.

Thereafter, at step 206, the flow rate of at least one fluid of the plurality of fluids may be calculated based on each of the flow rate of the final mixture and the flow rate of the at least one other fluid of the plurality of fluids to obtain the calculated flow rate. In an embodiment, the calculating may be performed by the PLC. Accordingly, the method may include measuring the flow rate of the at least one other fluid of the plurality of fluids by means of the at least one flow meter 120. Although FIG. 1 illustrates the at least one flow meter 120 configured for measuring flow rate of fluid flowing out of the tank 102a, it should be understood that the at least one flow meter 120 may be configured to measure flow rate of fluid flowing out of any tank of the at least one tank 102. For example, the at least one flow meter 120 may be situated on a path leading out of the tank 102c and configured to measure flow rate of fluid passing through the valve 110c. In an instance, the at least one fluid of the plurality of fluids may be such that it may not be preferable to measure the flow rate of the at least one fluid due to any reason. For example, the at least one fluid, such as for example, fluid flowing out of the tank 102b or the tank 102c, may be highly viscous making measurement of the flow rate technically difficult. As another example, the at least one fluid may be highly corrosive or abrasive on a flow meter used to measure the flow rate of the at least one fluid. Further, in an instance, the at least one other fluid may be such that it may be suitable to measure a flow rate of the at least one other fluid, such as for example, fluid flowing out of the tank 102a.

Further, details regarding the at least one fluid corresponding to the calculated flow rate are provided in conjunction with FIG. 1.

In an embodiment, the method may further include calculating a flow rate corresponding to each of at least two fluids of the plurality of fluids. The calculating may be performed, for example, by the PLC. Accordingly, in an embodiment, the relationship between the flow rate corresponding to each fluid of the at least two fluids and at least one other fluid of the at least two fluids may be predetermined. In another embodiment, the flow rate corresponding to each fluid of the at least two fluids may be expressible as the function of the flow rate of at least one other fluid of the at least two fluids. In an embodiment, the function may be the linear function. In yet another embodiment, the flow rate corresponding to each fluid of the at least two fluids may be a multiple of the flow rate of at least one other fluid of the at least two fluids. In an embodiment, the calculating may include subtracting the flow rate of the at least one other fluid of the plurality of fluids from the flow rate of the final mixture. In another embodiment, the calculating may include solving an underdetermined linear equation. Further, the flow rate of each fluid of the at least two fluids of the plurality of fluids may be constrained by each of an upper limit and a lower limit. In an embodiment, the PLC may be configured for solving the underdetermined linear equation based on linear programming.

In an embodiment, the method may further include controlling the flow rate of the at least one other fluid of the plurality of fluids based on each of the calculated flow rate and the predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture. The controlling may be performed by means of the at least one valve 110. In an embodiment, at least one valve 110 may be manually adjusted by an operator based on each of the calculated flow rate and the predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture. In another embodiment, at least one valve 110 may be automatically adjusted by the PLC by means of actuating at least one actuator coupled to the at least valve 110.

In another embodiment, the method may further include controlling the flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit 112 based on each of the calculated flow rate and the predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture. The controlling may be performed by means of the at least one valve 114. In an embodiment, at least one of the at least one valve 110 and the at least one valve 114 may be coupled to at least one actuator. Further, the PLC may control the at least one actuator. In another embodiment, the at least one valve 114 may be adjusted manually by an operator based on each of the calculated flow rate and a predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture.

In an embodiment, the method may further include displaying at least one of the flow rate of the final mixture, the calculated flow rate of at least one fluid of the plurality of fluids and the flow rate of the at least one other fluid of the plurality of fluids. The displaying may be performed on the display device.

In an embodiment, the method may further include computing the proportionality relationship among the plurality of fluids based on each of the flow rate of the final mixture, the calculated flow rate of at least one fluid of the plurality of fluids and flow rate of the at least one other fluid of the plurality of fluids. The computing may be performed by the PLC, in an embodiment. Further, the method may include displaying the

proportionality relationship on the display device.

Additionally, in an embodiment, the method may include transmitting at least one of the flow rate of the final mixture, the calculated flow rate of at least one fluid of the plurality of fluids, the flow rate of the at least one other fluid of the plurality of fluids and the proportionality relationship to the remote device. The transmitting may be performed by the transmitting unit coupled to the PLC. Further, the method may include receiving the command by means of the input unit of the remote device. The command may be received, for example, from an operator. Additionally, the method may include transmitting the command from the remote device to the PLC by means of the transmitting unit included in the remote device. Further, the method may include executing the command by means of the PLC. Moreover, executing the command may control at least one of the flow rate of the at least one other fluid of the plurality of fluids and the flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit 112. In an instance, executing the command may cause at least one of the flow rate of the at least one other fluid of the plurality of fluids and the flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit 112 to increase by at least one of a predetermined magnitude and an operator specified magnitude. In another instance, executing the command may cause at least one of the flow rate of the at least one other fluid of the plurality of fluids and the flow rate of at least one fluid of the plurality of fluids flowing into the second mixing unit 112 to decrease by at least one of a predetermined magnitude and an operator specified magnitude.

Additionally, in an embodiment, the method may include generating an alarm based on each of the calculated flow rate and the predetermined proportion of at least one fluid of the plurality of fluids required in the final mixture. In an instance, the alarm may be generated by the PLC.

In another embodiment, additionally the method may include determining the volume of at least one fluid of the plurality of fluids consumed from the at least one tank 102 during the time period during which the mixing of the plurality of fluids is performed. Furthermore, the method may include determining the volume of the final mixture generated during the time period. Further, the method may include printing at least one of the volume of the at least one fluid and the volume of the final mixture by means of the printer.

Turning now to FIG. 3, an apparatus 300 for mixing a plurality of fluids in accordance with an exemplary embodiment is disclosed. The plurality of fluids includes each of water and a viscous fluid. The viscous fluid, in an example, may comprise calcium carbonate. In an instance, a viscosity of the viscous fluid may be 7800 centipoises at a temperature of 17.9°C. Further, the viscous fluid may comprise microscopic glass particles.

In order to mix the viscous fluid with the water, the apparatus includes a pump 302 coupled to an outlet port of a first tank 304 containing the water. The pump 302 may be configured for pumping the water into a venturi injector 306. In an instance, the venturi injector 306 may be placed in physical proximity to a second tank 308 containing the viscous liquid. To keep the flow rate substantially constant in speed, the length of the path shall be limited up to a maximum length which is equal to 1 ,25 times the cross sectional area of the path, causing an excellent performance in supplying the fluid from the second tank 308 via a throat 312 of the venture injector 306 towards a third tank 336. The physical proximity being defined by a path length being equal to a threshold value n which shall not exceed a factor 1 ,25 multiplied by the cross sectional area of the path. In case the path is formed by a conduct having a circular cross section, the cross section having a internal cross sectional diameter of 20 mm, the path length shall, roughly, not exceed 400 mm. Preferably, the path length is in the range of 200 to 350 mm, more preferably, the path length is in the range of 260 to 340 mm. Most preferably, the path length is in the range of 280 to 320 mm. The path length defined according to this embodiment allows a one-way valve 318 to be placed between the second tank 308 and the throat 312 of the venture injector 306, the one-way valve 318 forming a portion of the path.

Accordingly, a hose 310 may be used to carry the water from the pump 302 to the venturi injector 306. Further, the venturi injector 306 may be configured such that a throat 312 of the venturi injector 306 is coupled to an outlet port 314 of the second tank 308. As a result, when the water flows through the venturi injector 306, the viscous fluid flows into the venturi injector 306 and mixes with the water. Thus, a mixture containing each of the water and the viscous fluid may be available at an outlet port 316 of the venturi injector 306. In an instance, a one-way valve 318 may be present along a path between the outlet port 314 of the second tank and the throat 312 of the venturi injector 306. The one-way valve 318 may be configured for allowing the viscous fluid flow from the second tank 308 to the venturi injector 306, while preventing a flow of the water from the venturi injector 306 to the second tank 308.

Further, the apparatus may include a static mixer 320 configured for receiving the mixture from the outlet port of the venturi injector 306. In an instance, a hose 322 may be used to carry the mixture from the outlet port 316 of the venturi injector 306 to an inlet port 324 of the static mixer 320. Additionally, the static mixer 320 may be configured for receiving the water from the first tank 304 through an adjustable valve 326.

Accordingly, the static mixer 320 may include a second inlet port 328 for receiving the water. Based on the state of the adjustable valve 326, the mixture flowing into the static mixer 320 may be diluted with the water. Further, the static mixer 320 may be configured for causing homogeneity in the mixture available at an outlet port 330 of the static mixer.

In an instance, it may be required to maintain a predetermined ratio of the viscous fluid to the water in the mixture. Accordingly, the apparatus 300 may further include a water flow meter 332 for measuring a flow rate of the water flowing out of the first tank 304. In an instance, the water flow meter 332 may be situated along a path of the water such that the water flow meter 332 measures total flow rate of water flowing out of the first tank 304. Additionally, the apparatus 300 may further include a mixture flow meter 334 for measuring a flow rate of the mixture flowing out of the outlet port 330 of the static mixer 320. The mixture may be collected in a third tank 336. Further, based on each of the flow rate of the mixture and the flow rate of the water, the adjustable valve 326 may be controlled in order to maintain the predetermined ratio. For example, the adjustable valve 326 may be controlled in such a manner that a difference between the flow rate of the mixture and the flow rate of the water may be substantially constant in time, for a given flow rate of the water. In an instance, an operator may monitor each of the flow rate of the mixture and the flow rate of the water at regular intervals of time. Further, if the operator notices that the difference between the flow rate of the mixture and the flow rate of the water is substantially different from a

predetermined constant, the operator may control the adjustable valve 326 in order to bring the difference substantially close in value to the predetermined constant. In another embodiment, each of the flow rate of the mixture and the flow rate of the water may be converted into digital information by means of a digital encoder (not shown in figure) included in the apparatus 300. Further, the apparatus 300 may include a

Programmable Logic Controller (PLC) (not shown in figure) configured for receiving digital information corresponding to each of the flow rate of the mixture and the flow rate of the water. In an instance, the PLC may be configured for subtracting digital information corresponding to the flow rate of the water from the digital information corresponding to the flow rate of the mixture in order to obtain a differential signal. In an

embodiment, the differential signal may be displayed to an operator by means of a display device coupled to the PLC. Accordingly, the operator may view the differential signal and control the adjustable valve 326 in order to maintain the predetermined ratio of the viscous fluid to the water. In another embodiment, the differential signal may be transmitted through one or more of a wired communication channel and a wireless

communication channel to a remote device. The remote device may be, for example, a mobile phone carried by an operator. Further, the differential signal may be displayed on a display of the mobile phone. As a result, the operator may be enabled to remotely monitor a ratio of the viscous fluid to the water in the mixture. In yet another embodiment, based on the differential signal, the PLC may be further configured for automatically controlling an actuator (not shown in the figure) coupled to the adjustable valve 326. In an instance, the PLC may be configured for automatically controlling the actuator in such a manner that the differential signal is maintained substantially close in value to the predetermined constant. In another embodiment, the PLC may be further configured for generating an alarm based on the differential signal. For instance, if the PLC determines that the differential signal has deviated in value from the predetermined constant by greater than a threshold amount, the alarm may be generated. Further, the alarm may be presented through one or more output devices such as, but not limited, a strobe light, a light emitting diode, an audio speaker and a buzzer. In an embodiment, a message, such as a Short Messaging

Service (SMS) message, corresponding to the alarm may be transmitted to the mobile phone of an operator.

In a further embodiment, subsequent to transmitting the differential signal to the remote device, the operator may input a command through an input unit of the remote device, such as the mobile phone. The input unit may be one or more of, but not limited to, a keypad, a touch-screen, a microphone, camera and a sensor. In an embodiment, the command may correspond to the actuator coupled to the adjustable valve 326. Further, the command may be for causing one or more of an increase in flow, a decrease in flow, closure of valve and opening of valve. Additionally, the command may include a magnitude corresponding to increase in flow and a magnitude corresponding to the decrease in flow. For example, the operator may input a command for causing an increase in flow of the water through the adjustable valve 326 by a specific magnitude.

Subsequently, the command may be transmitted through one or more of a wired communication channel and a wireless communication channel to the PLC. Further, the PLC may be configured to control the actuator coupled to the adjustable valve 326 based on the command received. As a result, the operator may be enabled to control the adjustable valve 326 from a remote location in order to maintain the predetermined ratio of the viscous fluid to the water.