Pipe arrangement for the pretreatment of drinking water and method for operating the pipe arrangement

Description

[0001] The invention relates to a line arrangement for the pretreatment of drinking water, comprising an inlet line and an outlet line, a line section arranged between the inlet line and the outlet line, at least one filter unit arranged in the line section, and a pump arranged in the line section. The invention also relates to a method for operating such a line arrangement.

[0002] When operating a drinking water system, it is particularly important to prevent or at least minimize the emergence and proliferation of potentially pathogenic germs and microorganisms.

[0003] One effective measure is to install a filter unit in the piping system, which acts as a barrier to keep germs and microorganisms out of the piping. In addition to the inlet and outlet, the filter units typically feature fine-pored filters such as microfilters, ultrafilters, nanofilters, or reverse osmosis filters.

[0004] These filter units generate a resistance that increases virtually linearly with the water flow rate, resulting in a pressure drop across the filter unit. At a small decrease, only a small pressure drop occurs across the filter.

[0005] Water demand fluctuates considerably in all drinking water systems, especially in larger ones. For example, the showers in a hotel are often used simultaneously by many guests, especially early in the morning.

[0006] Therefore, the filters in the filter units are designed in terms of their filter area so that the water pressure downstream of the filter unit remains sufficiently high even when there is a high water draw-off, so that a minimum pressure is maintained in the pipe arrangement, which is required, for example, when showering.

[0007] Therefore, filter systems must always be designed specifically for the property and very large to handle peak flow without excessive pressure drop. However, most of the day, there is little or no water withdrawal. Therefore, a filter system designed for peak flow rarely actually flows as designed.

[0008] However, if filters in filter units, which represent a large contact surface with the water, are not, rarely, and / or only insufficiently flowed through, they provide a suitable surface for microorganisms to colonize. A solution to the problem of stagnation is described in EP 2 474 506 B1. This involves a pump in a bypass or return line that ensures flow even when no water is being drawn off.

[0009] DE 11 2017 001324 T5 (D1) discloses a water purifier with a filter device. A booster pump for operating the water purifier is switched on when the measured pressure is above a first predetermined pressure and switched off when the measured pressure is below a second predetermined pressure.

[0010] Therefore, the present invention is based on the technical problem of constructing a compact and easily standardizable pipe arrangement for the pretreatment of drinking water.

[0011] The technical problem outlined above is solved according to the invention in a line arrangement of the type mentioned at the outset in that a measuring device is provided for measuring the pressure difference between the inlet and the outlet of the filter unit, that a control unit connected to the measuring device is provided, that the control unit is set up to control the pump to at least partially compensate for the pressure difference above a predetermined limit value of the pressure difference and that the control unit is set up to switch the pump off below a predetermined second limit value.

[0012] The described line arrangement thus features a filter unit whose filter area no longer needs to be designed for the peak flow rate, i.e., the assumed maximum flow rate at a given pressure difference. The use of the additional pumping capacity increases the inlet pressure upstream of the filter unit and thus leads to an increased flow rate through the filter unit, thereby reducing the pressure drop in the flow direction downstream of the filter unit.

[0013] The surface area of ​​the filter, for example, the filter membrane, within the filter unit is therefore no longer designed for a maximum pressure difference at an assumed peak flow rate, but rather for a significantly lower flow rate. To prevent an undesirable pressure drop at high flow rates, the pump is designed to compensate for the necessary pressure difference.

[0014] This allows compact and cost-effective filter units to be built into pipe arrangements that consistently deliver hygienically clean water to the installation. The filter systems therefore no longer need to be adapted to each individual pipe arrangement; in fact, they can be easily standardized. This results in economies of scale and cost-effective improvements.

[0015] The advantages of the described piping arrangement are a compact design, filters with little space requirement and avoidance of pressure drop in the piping arrangement.

[0016] The phrase "configured" for specific control functions means that the control unit has a programmable electronic circuit, is connected to the pressure sensors via a cable and / or radio link, and records measured values. It is also connected to the pump to be controlled via a cable and / or radio link and transmits control signals. The control unit evaluates the recorded measured values ​​using an algorithm running in the electronic circuit, generates control signals according to the control instructions and conditions, and transmits the control signals to the pump.

[0017] Preferably, the filter of the at least one filter unit is made of ceramic, in particular a ceramic membrane, stainless steel, in particular a stainless steel membrane, or a hard plastic. These filters are resistant to particularly high pressure differences of, for example, 2 to 10 bar. The filter unit is thus designed to be robust enough to withstand very high pressure differences.

[0018] Furthermore, a bypass line is provided, which serves to recirculate the filtered water and can thus also be referred to as a return line. The control unit is configured to generate a volume flow through the filter unit and the bypass line using the pump. The bypass line can also be equipped with a pump. The circulation of the water through the bypass line and the filter unit prevents stagnation on the clean water side of the filter or a low flow through the filter. This permanently and reliably prevents the risk of retrograde contamination of the clean water side.

[0019] In a further preferred manner, no backflow preventer or valve is arranged in the described line section and in the bypass line, so that in the event of particularly high water demand, a partial flow can flow via the bypass line directly to the outlet line without having previously flowed through the filter unit.

[0020] Alternatively, it may be advantageous to install a backflow preventer, particularly a check valve, in the outlet line and / or in the bypass line. If the backflow preventer is located in the bypass line, this reliably prevents unfiltered tap water from reaching the outlet line. If, on the other hand, the backflow preventer is located in the outlet line, it prevents the clean water side of the filter unit from being exposed to unfiltered water.

[0021] The technical problem outlined above is also solved according to the invention by a method for operating a line arrangement for the pretreatment of drinking water, in which a volume flow is generated through a filter unit by withdrawing drinking water, in which the pressure drop across the filter unit is measured, in which a pump is switched on to generate pressure equalization when the pressure drop exceeds a first limit value, and in which the pump is switched off when the pressure drop falls below a second limit value.

[0022] The described method has the same properties and advantages as those described in connection with the line arrangement.

[0023] Preferably, after a predetermined period of time following the last activation, the pump is activated to generate a volume flow through the filter unit and through a bypass line. This achieves the circulation described above to prevent stagnation.

[0024] In the following, the invention is explained using exemplary embodiments with reference to the drawing. Fig. 1 shows a first embodiment of a line arrangement according to the invention, Fig. 2 shows a second embodiment of a line arrangement according to the invention and Fig. 3 shows a third embodiment of a line arrangement according to the invention.

[0025] In the following description of the various embodiments according to the invention, components and elements with the same function and the same mode of operation are provided with the same reference numerals, even if the components and elements in the various embodiments may have differences in their dimensions or shape.

[0026] Fig. 1 shows a first embodiment of a pipe arrangement 2 for the pretreatment of drinking water. The pipe arrangement 2 has an inlet line 4 and an outlet line 6, which are provided with shut-off valves 4a and 6a. The inlet line 4 is connected to the municipal water main, and the outlet line is connected to the drinking water installation installed in the associated building or buildings. The drinking water installation supplies individual consumption points within the building, such as sinks, toilet flushes, and showers.

[0027] Between the two lines 4 and 6, a line section 8 is arranged in which a filter unit 10 is arranged, which is provided with a fine-pored filter for filtering out germs and / or microorganisms.

[0028] Furthermore, a pump 12 is arranged in the line section 8, which can generate an additional pressure build-up in the line section 8.

[0029] Furthermore, a measuring device 14 with pressure sensors 14a and 14b is provided for measuring the pressure difference between the inlet 16 and the outlet 18 of the filter unit 10.

[0030] A control unit 20 (dashed lines) is connected to the pressure sensors 14a and 14b to evaluate the measured values ​​of the pressure sensors 14a and 14b. This allows the control unit to determine the pressure difference ΔP between the two measuring points.

[0031] The control unit 16 is connected to the pump 12 via a line (shown in dashed lines) and is further configured to control the pump 12 above a predetermined first pressure difference limit value ΔP 1 to at least partially compensate for the pressure difference. The operation of the pump 12 causes an increased amount of water to flow through the filter unit 10 and build up an increased pressure on the outlet 18 side, which reduces the pressure difference ΔP.

[0032] The control unit 20 is further configured to shut off the pump below a predetermined second limit value ΔP 2. This prevents excessive pressure from building up on the outlet 18 side of the filter unit 10.

[0033] The two limit values ​​ΔP 1 and ΔP 2 can be chosen to be equal. However, ΔP 1 is preferably greater than ΔP 2 in order to implement a hysteresis and prevent excessive switching on and off of the pump 12.

[0034] Furthermore, the filter of the filter unit 10 is made of ceramic, in particular a ceramic membrane, of stainless steel, in particular a stainless steel membrane, or of a hard plastic. These materials are resistant to particularly high pressure differences of, for example, greater than 2 to 10 bar, preferably 2 to 5 bar. The filter module is therefore designed so robustly that it can withstand a very high pressure difference.

[0035] Fig. 2 shows a further embodiment of a line arrangement 2 according to the invention, in which the same reference numerals identify the same components as in connection with Fig. 1 have been described.

[0036] In addition to the line section 8, a bypass line 22 is provided, and the control unit 20 is configured to generate a volume flow through the filter unit 10 and through the bypass line 22 by means of the pump 12. The bypass line 22 functions to recirculate the filtered water and can thus also be referred to as a recirculation line. Thus, when there is no or only very little water drawn through the outlet line 6, operating the pump 12 results in a volume flow through the filter unit to protect it from stagnation.

[0037] If, however, a large amount of water is withdrawn from the line arrangement 2 via the outlet line 6, the pressure in the section located downstream of the filter unit 10 can be increased by the pump 12, as described. If the volume flow through the outlet line 6 continues to increase, a partial flow of water can also increasingly flow through the bypass line 22 into the drinking water system connected to the line arrangement 2 without being filtered in the filter unit 10.

[0038] When designing the Fig. 2 In the illustrated embodiment, a reservoir 24 is also arranged in the bypass line 22 for the temporary storage of drinking water, in which unfiltered or filtered drinking water is stored. When a peak volume flow of drinking water is then requested, filtered water stored there can flow directly into the installation for an initial period of time during which the peak volume flow occurs. During extremely high peak consumption, unfiltered water can also flow into the installation for a short time.

[0039] Fig. 2 shows, as a further option, the arrangement of a check valve 26 in line section 6. The check valve 26 ensures that no unfiltered drinking water can reach the downstream outlet 18 of the filter unit 10 or into the bypass line 22. In particular, the clean side of the filter remains unaffected. Nevertheless, the check valve 26 does not prevent circulation through line section 8 and the bypass line 22 during operation of the pump 12.

[0040] Fig. 3 shows a similar arrangement as in Fig. 2 , where the same reference numerals refer to the same components as in the Fig. 1 and 2 mark.

[0041] In this embodiment, a further check valve 28 in the form of a diaphragm expansion vessel is arranged on the upstream side of the reservoir 24. The check valve 28 prevents the inflow of unfiltered drinking water from the municipal supply via the inlet line 4 into the line arrangement 2 and thus into the connected drinking water system. However, the check valve 28 does not prevent circulation through the line section 8 and the bypass line 22 during operation of the pump 12.

[0042] Filtered drinking water is temporarily stored in the bypass line 22 in the reservoir 24. If a short-term peak volume flow of drinking water is then requested, this reservoir can be used to maintain the pressure in the outlet line 6 for an initial period of time during which the peak volume flow occurs, without an excessive pressure drop occurring.

[0043] The following example is given. The water pressure at the house entrance from the municipal supply, and thus in inlet line 4, is 4 bar. The minimum desired pressure in the drinking water installation connected to line 2 is 3 bar. The maximum flow rate is assumed to be 20 l / min. The fine-pored filter in filter unit 10 is dimensioned such that, at the assumed maximum flow rate of max. 50% of the peak flow rate, the pressure drop ΔP 1 is a maximum of 1 bar.

[0044] Pump 12 is then designed to apply additional pressure when needed, i.e., when the pressure difference ΔP 1 exceeds 1 bar, to compensate for the additional pressure drop at the peak flow rate. The pump is then switched off again when the pressure drop ΔP 2 is less than 0.8 bar. This prevents the pump from being switched on and off too frequently.

[0045] However, if no water is drawn off over a period of, for example, 6 hours, the pump 12 is switched on for a predetermined period of approximately 30 minutes, regardless of the occurrence of a peak volume flow, in order to prevent prolonged stagnation on the filter surface in the filter unit 10.

Claims

1. Piping arrangement for the pre-treatment of drinking water - with an inlet pipe (4) and an outlet pipe (6), - with a pipe section (8) arranged between the inlet pipe (4) and the outlet pipe (6), - with at least one filter unit (10) arranged in the pipe section (8) and - with a pump (12) arranged in the pipe section (8) and characterised - in that a measuring device (14; 14a, 14b) is provided for measuring the pressure difference between the inlet (16) and the outlet (18) of the filter unit (10), - in that a control unit (20) connected to the measuring device (14; 14a, 14b) is provided, - in that the control unit (20) is configured to, above a predetermined first limit value of the pressure difference, actuate the pump (12) in order to at least partially equalise the pressure difference, and - in that the control unit (20) is configured to, below a predetermined second limit value, switch off the pump (12).

2. Piping arrangement according to claim 1, characterised in that the filter of the at least one filter unit (10) is made of ceramic, in particular of a ceramic membrane, or of stainless steel, in particular of a stainless steel membrane.

3. Piping arrangement according to claim 1or 2, characterised - in that a bypass line (22) is provided and - in that the control unit (20) is configured to generate a volume flow through the filter unit (10) and through the bypass line (22) by means of the pump (12).

4. Piping arrangement according to one of claims 1 to 3, characterised in that a backflow preventer (28, 28) is arranged in the pipe section (8) and / or the bypass (22).

5. Method for operating a piping arrangement for the pretreatment of drinking water, - in which a volume flow through a filter unit is generated by extracting drinking water, - in which the pressure drop across the filter unit is measured, - in which, when reaching the pressure drop above a first limit value, a pump is switched on to generate a pressure equalisation, and - in which, when the pressure drop falls below a second limit value, the pump is switched off.

6. Method according to claim 5, in which, after a preset period of time following a last switch-on, the pump is switched on to generate a volume flow through the filter unit and through a bypass line.