[0001] The present invention refers to a method for measuring various parameters, such as conductivity, temperature, pH value, flow-rate, pressure, etc., in fluids with the help of semipermeable membranes, which separate the solute from the solvent following the principle of reverse osmosis, and to the device for carrying out that method.

[0002] Document US 2014180610 describes a similar solution, which proposes the use of a battery-powered conductivity sensor, which limits the lifespan of the device and requires relatively frequent maintenance or battery replacements. Moreover, the use of batteries conditions the size of the electronic circuit and, consequently, the entire sensor.

[0003] Furthermore, document US 2011114561 describes a solution where a generator (rotor), which is located in the central pipe of the membrane and powered by the fluid flow, is used as a power source. To function, said solution requires a constant flow; hence, it can only function in a liquid fluid with a sufficient flow-rate.

[0004] Furthermore, document EP 1937386 describes a solution, which proposes the use of WLAN wireless communication for the transmission of measured data, demanding a large energy supply, such as a battery or other types of wired power supply.

[0005] Furthermore, document EP 2471591 describes a solution, which proposes the data to be transmitted with the help of an antenna inserted between the reverse osmosis membrane and the interior wall of the high-pressure pipe, which works according to the principle of electromagnetic waves.

[0006] It is the object of the present invention to create a device for real-time measurements of various parameters, such as conductivity, temperature, pH value, flow-rate, pressure, etc., in fluids with the help of semipermeable membranes, which separate the solute from the solvent.

[0007] Furthermore, the objective of the present invention is to develop a new method for real-time measurements of various parameters, such as conductivity, temperature, pH value, flow-rate, pressure, etc., in fluids with the help of semipermeable membranes, which separate the solute from the solvent.

[0008] The object as set above is solved, according to the present invention, by features according to the characterising part of the claim 1. Details of the invention are disclosed in the corresponding sub-claims.

[0009] The invention is further described in detail by way of non-limiting embodiment, and with a reference to the accompanying drawings, where

Fig. 1 shows a series of pipes for fluid desalination arranged in a battery;

Fig. 2 shows a longitudinal cross-section of one of the pipes in said battery of Fig. 1;

Fig. 3 a measuring device according to the invention;

Fig. 4 a schematic view of a measuring unit; and

Fig. 5 a schematic view of a communication and a processing unit.

[0010] A method for measuring various parameters, such as conductivity, temperature, pH value, flow-rate, pressure, and similar, in fluids is described in continuation using a non-limiting embodiment of the method for desalination of water with a help of semipermeable membranes 1, which follow the principle of reverse osmosis to separate water, i.e., the solvent, and salt, i.e., the solute. It is obvious that the method and the device according to the invention are not limited merely to the desalination of water, but can be used in other methods, such as separating water from milk, etc.. Said membranes 1 are typically cylindrical in shape, and a series of multiple identical membranes 1 is inserted in series into each high-pressure pipe 2, whereby a series of pipes 2 is arranged in a tubular battery 3 (shown in Fig. 1 with a dash-dotted line). Neighbouring membranes 1 from said series of membranes are separably connected to each other with a connecting tubular extension 4. Into an opening 5 of each high-pressure pipe 2, saltwater is supplied, which during the method flows in the direction of the arrow A through all the membranes 1. Desalinated (permeate) water, which passes through the membranes 1, flows into a main permeate pipe 6, while the remaining saltwater concentrate is eliminated at an outlet 7 of each high-pressure pipe 2. The conductivity of the permeate water is measured in the area of the output end of each membrane 1 or in the junction area with the neighbouring membrane 1.

[0011] Water leaving the first membrane 1 from the series of sequential membranes 1 in each pipe 2 is the most desalinated water and conductivity thereof is low; after the last membrane 1 from the series of sequential membranes 1 in each pipe 2, water is the least desalinated and conductivity increases slightly. When the conductivity of water, measured by at least one of sensors of various parameters, such as conductivity, temperature, pH value, flow-rate, pressure, and similar, does not correspond to the predetermined range, it means that at least one said membrane 1 is faulty and that the desalinated water in the main pipe 6 no longer meets the quality requirements. At least one said sensor, where the surplus value is measured, directly indicates which of the membranes 1 in the pipe 2 is faulty.

[0012] A device according to the invention for real-time measurements of various parameters, such as conductivity, temperature, pH value, flow-rate, pressure, etc., comprises an internal measuring unit 8 and an external communication and processing unit 9. Said internal unit 8 of the device according to the invention is located in the central pipe 6 in the end section, as observed in the direction A of the flow, of each membrane 1 and directly before said connecting tubular extension 4. Said external unit 9 of the device according to the invention is located directly on the high-pressure pipe 2 and in the area directly above said internal unit 8. The essence of the present invention is in the fact that said internal measuring unit 8 is both powered by and also communicates with said external communication and processing unit 9 on the basis of the wireless cooperation.

[0013] Based on the present invention, it can be provided that the last of all said units 8, as observed in the direction A of the flow, can also be installed inside the output pipe, but not in the area of the last membrane 1 or high-pressure pipe 2.

[0014] Said internal, cylinder-like measuring unit 8 of the device according to the invention can be tightly inserted inside the central pipe 6 and comprises at least one measuring electrode 10; 10’, which is in direct contact with the fluid, the parameters of which are being measured, and an internal induction element 11, such as a coil, arranged tightly about the external rim of said cylinder-like measuring unit 8 and is isolated from the fluid, the parameters of which are being measured. Said internal unit 8 further comprises a processor 12, which is connected by means of an excitation circuit 13 to the first measuring electrode 10 and which produces a sinusoidal signal on said first measuring electrode 10, an analogue-to-digital converter 14 for receiving the analogue signal captured at the second measuring electrode 10’, and converting said analogue signal into a digital signal, which is suitable for digital processing and transmission, and at least one sensor 15, such as a sensor for temperature, flow-rate, pressure, pH value, and similar, for measuring at least one parameter of the fluid, which contains at least one said electrode 10; 10’. Said internal induction element 11 is connected through a power supply module 16 and a communication module 17 to the processor 12, wherein said connection enables energy supply as well as the disruption of resonance conditions or frequency of said internal unit 8 with the help of an external communication and processing unit 9. Furthermore, said connection allows data to be transmitted to said external communication and processing unit 9 of the device according to the invention.

[0015] As already mentioned, said internal measuring unit 8 of the device according to the invention is inserted into the central pipe 6, wherein it is surrounded by the fluid, the parameters of which are being measured, such as a gas, vapour, liquid. Only at least one said measuring electrode 10; 10’ is in direct galvanic contact with the fluid, the parameters of which are being measured, while the remaining electronic components of said measuring unit 8 are impermeably isolated from said fluid.

[0016] In the first step of the method according to the invention, the power supply of said external communication and processing unit 9 is switched on, which based on wireless cooperation, specifically based on inductive coupling of units 8; 9, activates said measuring unit 8, which in turn starts measuring the conductivity of the fluid that at least one of said electrodes 10; 10' is in direct contact with. The measured data obtained in this manner is transmitted by said measuring unit 8 based on wireless cooperation to said external communication and processing unit 9 of the device according to the invention, which processes the obtained measured data and transmits them further on.

[0017] Each internal measuring unit 8 of the device according to the invention has its own external communication and processing unit 9 of the device, together with which it forms an inductive couple, whereby said wireless cooperation is bidirectional.

[0018] Said external communication and processing unit 9 of the device according to the invention comprises a processor 18, which is connected through an excitation circuit 19 to an external induction element 20, such as a coil, for said wireless cooperation with said internal measuring unit 8 of the device according to the invention, whereby said external induction element 20 is reverse-connected though a first communication module 21 to said processor 18. Furthermore, said external induction element 20 is provided for wireless cooperation with said external communication and processing unit 9 of the device according to the invention. Furthermore, it is provided for that the external communication and processing unit 9 of the device according to the invention comprises a second communication module 22 for receiving measured data obtained from the internal measuring unit 8, which had been processed by the processor 18, for transmitting data processed with the processor 18 to a data hub 23, and for transmitting commands from the data hub 23 back to the processor 18.

[0019] Said external communication and processing unit 9 of the device according to the invention, which is powered by energy through a power supply port 24, is not in contact with the fluid, the parameters of which are being measured, and is typically located on the external rim of the high-pressure pipe 2 so that said unit 9 is arranged in a ring around the high-pressure pipe 2 and is, as seen in the transverse plane according to the extension of the pipe 2, located in an area directly above or around the internal measuring unit 8 of the device according to the invention. The main functions of the external communication and processing unit 9 are to follow the prompts of the data hub 23 and based on inductive coupling activate the internal measuring unit 8 of the device, to receive data obtained by the internal measuring unit 8, to process this data, and to transmit the processed data to the data hub 23. The external communication and processing unit 9 is powered by energy, such as wired or battery power supply, and connected for communication purposes, namely through protocols such as RS485 or CAN, with the data hub 23, which controls the entire battery 3 of high-pressure pipes 2. The data hub 23 functions as a control hub for the battery 3 of high-pressure pipes 2, and is connected to all the measuring devices according to the invention. Based on the pre-set time, the data hub 23 turns on selected measuring units inside the battery, for instance in a way that two measuring devices at the same location are not turned on simultaneously, which prevents interference with neighbouring devices.

[0020] Upon establishing a stable electrical voltage power on the internal measuring unit 8 of the device, the device automatically takes a measurement of at least one fluid parameter, such as conductivity, temperature, flow-rate, pH value, and similar. Based on the set time period or the current requirement, the communication and processing unit 9 of the device according to the invention activates the external induction element 20 at a set frequency, such as 133kHz, which triggers the wireless power supply of the internal measuring unit 8 of the device. The maximum power transfer between the communication and processing unit 9 and the internal measuring unit 8 of the device according to the invention is ensured by the excitation circuit 19 of the communication and processing unit 9 which, upon comparing the phase between the excitation signal of the external communication and processing unit 9 and the signal on the external induction element 20, sequentially tunes the oscillator circuit and thus ensures the resonance excitation of the internal induction element 11 of the internal measuring unit 8 of the device. The measurement starts with the excitation of the sinusoidal signal on the first electrode 10, which due to the conductivity of the fluid causes a response on the second electrode 10’ that reads the signal. The difference between the amplitude and phase of the generated signal on the first electrode 10 and the amplitude and phase of the measured signal on the second electrode 10’, which is the result of complex resistance, i.e. impedance, of the fluid, determines the conductivity of the fluid which the electrodes 10; 10’ are located in. In addition to the measurement of fluid conductivity, a measurement of fluid temperature is taken simultaneously. The final data on fluid conductivity is calculated to indicate the conductivity of the fluid at 25°C.

[0021] Furthermore, the measured data is compressed in a data package, which the internal measuring unit 8 transmits with the help of said inductive cooperation of units 8; 9 to the communication and processing unit 9. The communication between the internal measuring unit 8 and the communication and processing unit 9 of the device is facilitated by the disruption of the resonance conditions or by detuning the internal, measuring unit 8 of the device. Thereby, the external communication and processing unit 9 detects said disruption of resonance conditions either as a phase deviation or phase modulation or as an electrical current variation on the external measuring unit 9, which results in the proper decoding of said data. The wireless power supply of the internal measuring unit 8 with the help of said inductive cooperation of units 8; 9 is cut after the measured data has been successfully received or after a set amount of time has lapsed.