EP3033575A1

EP3033575A1 - Disinfection in a centrifugal pump or in a pump system having at least one centrifugal pump

Info

Publication number: EP3033575A1
Application number: EP14747841.6A
Authority: EP
Inventors: Martin Schwarz; Daniel BÜNING
Original assignee: Wilo SE
Current assignee: Wilo SE
Priority date: 2013-08-13
Filing date: 2014-08-04
Publication date: 2016-06-22
Also published as: DE102013013543A1; DE102013013543B4; WO2015022060A1

Abstract

The invention relates to a method for thermal disinfection in a centrifugal pump, or in a pump system having at least one centrifugal pump, conveying drinking water, service water, waste water, or other liquid media. Said centrifugal pump or pump system has a suction port terminating at the suction side of the centrifugal pump or the pump system, and has a pressure port terminating at the pressure side. When the suction port and/or the pressure port is/are closed, the centrifugal pump or the pump system conveys the medium in a cycle via a connection that is located inside the centrifugal pump or the pump system and that hydraulically short-circuits the pressure side with the suction side intermittently such that the medium, and thus the parts of the centrifugal pump or the pump system touching the medium, are heated to a disinfecting temperature.

Description

Disinfection in a centrifugal pump or in at least one

Centrifugal pump system contained

The invention relates to a method for thermal disinfection in a drinking / drinking water, wastewater or other liquid media promotional

Centrifugal pump or pump system with at least one centrifugal pump, which / has an opening to the suction side of the centrifugal pump or the pump system suction port and opening to the pressure side pressure port. The media used in the pump or in the pump system may be, for example, drinking or service water,

Industrial waters, waste or sewage or other media act.

It is known to physically or chemically disinfect a centrifugal pump or a pump system with centrifugal pump to kill or inactivate microorganisms. For this purpose, for example, in the case of thermal disinfection, the heating of the medium is costly heated by an external heat source. In chemical disinfection is an external provision of

Disinfecting solution necessary. Further, in the chemical

Disinfection method disadvantageous that the materials / components can be chemically attacked in the pump or in the pump system. This can lead to material damage, leaks and shortened life. In addition, unwanted and harmful chemical

Reaction products arise.

CONFIRMATION COPY The object of the invention is to provide a method for disinfection in centrifugal pumps and pump systems with at least one centrifugal pump, which is technically less expensive and requires no chemicals.

This object is achieved in that the centrifugal pump or the pump system with a closed suction or

closed pressure port, the medium via a the pressure side with the suction side hydraulically temporarily short-circuiting within the centrifugal pump or the pump system befindliches connection such in circulation promotes that the medium and thereby the media-contacting parts of the centrifugal pump or the pump system to a predetermined, disinfecting temperature, e.g. 70 ° C is heated, and this unfolds over a certain exposure time in particular of at least 3 minutes, a disinfecting effect. In this case, the flow of the heated medium in the surrounding system through

Shutting off the pressure or suction port e.g. be prevented by valves in the system near the pump. As a rule, shut-off valves are located directly on the pump in order to ensure convenient removal during servicing.

Due to the prevalence of these conditions, all microorganisms in the circulating medium and the media-contacting pump parts such as on the inner walls of the pump, the impeller and possibly in the lines and channels of the pump system safely killed or inactivated.

This also includes the media-contacting parts of circulating elements. Typical elements are valves, especially shut-off valves for simplified service work, control valves or also pressure reducing valves, furthermore non-return valves, especially gravity brakes or

Check valves, furthermore expansion tanks, especially membrane,

Bellows or piston accumulator, further filters, especially sieve or

Membrane filter, furthermore sensor technology, especially pressure or flow sensors or water meter.

There are no additional technical expenses in the form of an additional heat source or chemicals required. A more obvious approach seems to be to operate the pump against a closed valve at the pressure port of the pump, but the method presented here has three advantages:

First, the warm-up time is significantly shortened because of the high

Flow velocity in the circuit more electric power from the

Centrifugal pump or the pump system is recorded, and this increased absorbed power is largely translated into the heating of the medium. Fig. 2 shows this comparison.

Second, the maximum temperature achievable by the process is increased because the shortened warm-up time does not heat the entire casing of the centrifugal pump or the pump system, but instead

mainly the media-contacting part of the centrifugal pump or the

Pump system. This reduces the heat losses over the

Housing, and allow only for small enclosures with small motors until reaching a disinfecting temperature such as 70 ° C.

Third, the temperature distribution through the promotion in the circulation is much more homogeneous, so that a more uniform heating of the medium and the media-contacting pump part takes place. Accordingly, the effect of the later disinfection is also more uniform, and the more secure the detection of the medium temperature is with e.g. only one measuring point.

The proposed method can be applied to all centrifugal pumps such as single-stage horizontal pumps and pump systems with at least one centrifugal pump, such as pressure booster systems with multistage vertical centrifugal pumps. It is advantageous if suction and pressure side are spatially close to each other, because then the connection between the two can be made relatively easy. Preferably, this connection between the pressure and the suction side is an externally operable shut-off device for opening and closing the connection. Here, for example, the obturator in be stored a pump outer wall of the pump housing of the centrifugal pump, as shown in FIG. 1.

The medium may be a specially introduced for the process medium such as demineralized water or disinfectant or cleaning solution, for. when heating, to increase the disinfecting effect or to achieve positive side effects. This is particularly advantageous when the

Heating the medium pumped during normal operation of the centrifugal pump or the pump system to negative side effects, e.g. Precipitation of lime leads. Alternatively, the medium delivered in normal operation of the centrifugal pump or the pump system can also be used, or a mixture of both. If necessary, therefore, the centrifugal pump or the pump system must be closed both at the suction connection and at the pressure connection, a part of the medium conveyed in normal operation be drained off, and optionally the desired medium be introduced simultaneously.

In this method, the temperature of the medium is detected, whether by direct measurement via a sensor in the medium or on the pump casing, be it an observed quantity such as the power consumption and a fluid temperature calculation model or an estimated value. In this case, it is possible to resort to permanently existing temperature detections, or the detection is set up only temporarily, e.g. for the period of the procedure with a contact sensor.

For the measurement with a sensor, a measuring point is preferably selected which has a high heat transfer from the medium to the measuring point. In the case of multistage centrifugal pumps, for example, For other centrifugal pumps or pump systems, it makes sense to design a measuring point, which receives a high heat transfer from the medium to this measuring point by special design and appropriate choice of materials. This results in a reliable measurement result.

This detected temperature value is included in a control of the pump operation, so that the predetermined temperature of, for example, 70 ° C complied becomes. This means that, for example, in speed control of the centrifugal pump by a frequency converter, the speed is selected depending on the difference between the detected temperature and the predetermined temperature; During warm-up, therefore, the maximum speed is selected in order to introduce as much heat as possible into the medium. If there is no speed control, eg a two-point control can be realized by switching the centrifugal pump on and off.

From a temporal sequence of predetermined temperatures, a temporal temperature profile is then created from predetermined temperatures or detected temperatures, such as e.g. a recorded media temperature of 70 ° C over a period of at least 3 minutes, see Fig. 2. By the

Prevalence of these conditions are all microorganisms in the

circulating medium and safely killed or inactivated on the media-contacting pump parts such as on the inner walls of the pump, on the impeller and possibly in the lines and channels of the pump system. There are no additional technical expenses in the form of an additional heat source or chemicals required.

Preferably, this method is a proof of the

disinfecting effect supplemented by detecting the prevalence of the disinfecting temperature over the necessary period of time. This proof can therefore be in the form of a protocol in which the recorded temperature profile is displayed. Preferably, however, a material is used that changes its state as a result of the influence of temperature over the necessary period of time. This can e.g. a coating or even a sticker that discolors. The position of this material is selected analogously to the measuring point so that a high heat transfer from the medium to the measuring point is ensured.

Subsequent cooling of the reaction space takes place e.g. by draining the heated medium and flowing cold medium, for. B. by opening a drain valve, which is preferably the shut-off valve simultaneously.

Preferably, this also takes place in the circulation within the centrifugal pump or the pump system, so that a uniform cooling is achieved by homogeneous temperature distribution, and thus the temperature detection works more reliable. The heat transfer to the medium is kept low, z. B. by an intermittent operation by turning on and off the centrifugal pump or by speed control of

Centrifugal pump at low speeds. For the protection of the operator and the pump material is preferably waited until the medium, e.g. cooled to 40 ° C, see Fig. 2.

Preferably, the opening of the short-circuiting connection and the start of the control operation along the temperature profile is not done manually, but is automated. This requires in particular an electric valve in place of the shut-off valve, as well as automated devices for

Close the pressure or suction connection and then drain the medium. This additional expense brings the benefit of this method of thermal disinfection in hygienically critical systems e.g. can be performed at fixed time intervals.

An embodiment of the invention is illustrated in the drawing and will be described in more detail below. Show it

1 shows an axial section through a four-stage pump,

Fig. 2 is a temperature / time diagram.

A one, two or more stages engine centrifugal pump 1 has in

Embodiment four wheels 2, which are mounted on a vertical pump shaft 3. The pump shaft is from one above the pump 1

powered electric motor, whose motor shaft coaxial with the

Pump shaft is connected or merges coaxially into the pump shaft, possibly via a coupling.

In the four stage housings of the four pump stages is in each case an impeller 2, wherein the cylindrical outer walls 7 of the stage housing are coaxial one above the other and form a total wall, of a Pump outer wall 8 is coaxially surrounded such that between the

Total wall and the pump outer wall 8 an annular space 9 consists. In this case, the suction side 1 has a suction chamber, which is connected to the suction nozzle 13. Further, located above the uppermost stage housing 6, a pressure chamber 0 with a pressure port, wherein the drinking or service water is conveyed from the pressure chamber via the annular space 9 down to the pressure port.

The annular space 9 also surrounds the lower suction chamber 11, wherein the

Suction chamber is separated from the annular space by a cylindrical wall in which there is a connection opening which forms a connection 15 between the annular space 9 and the suction chamber 11. If the connection 15 or the connection opening is opened, then the pumped medium flows in the circuit through the pump according to the three arrows 17. Here, one of the surrounding check valves, at the pressure port or at the suction port of the pump, closed, so that the pump no longer can promote outside. In general, these check valves are located directly on the pump to be in

Service case to ensure a comfortable expansion.

To close the connection 15 and the connection opening is a shut-off (check valve) 18 with a locking member, which in the

Pump outer wall 8 is mounted and actuated by the outside

Rotary adjustment is brought into the connection opening to close the connection 15 for normal operation.

The medium circulation enabling connection 15 may instead of a

Connection opening also be formed by a connecting channel. This depends on the design of the pump. Here, a check valve is then arranged in the connecting channel, which can be actuated from the outside. Preferably, the shut-off valve 18 and the locking member is electrically actuated.

For disinfection in a drinking water or service water pump, the pressure-side service valve is closed to prevent water loss. In addition, a circuit in the pump is made possible by opening the connection 15, eg by unscrewing the locking member. Compared to heating without circulation, the following values are increased:

- the flow rate (from 0 to about the maximum flow rate of the pump),

- the power consumption of the pump

- and accordingly the power to the water

Due to the occurring turbulences, the mixing in the pump is better, so that set more homogeneous temperatures. The circulating in the pump water is preferably heated to 70 ° C.

Subsequently, the achieved water temperature of> 70 ° C for e.g. held for three minutes by the heat supply is controlled by the pump speed and thereby the pump is disinfected, as shown in FIG. 2. For compliance with normative specifications, this process is monitored, in particular via temperature sensors. The compliance with these specifications is preferably documented directly on the basis of a proof. This document may include a graph of the temperature history over time.

The heated water is drained directly via the drain plug and the pump is flushed with cold fresh water. Here, too, the internal circulation is preferably used, and with low speeds to increase the heat transfer from steel to water. This is called

Individual action as needed or as a precautionary measure in certain

Intervals performed.

In the case of pump systems, in particular in pressure boosting systems, the entire system and not the individual pumps are exhausted on the pressure side. In addition, a connection between suction and pressure side is made, so that a water exchange takes place from the pressure to the suction side. Thus, the water in the bar is heated sufficiently for the disinfecting effect.

The short-circuiting connection is preferably equipped with sensors such as temperature and flow meter. The detection of the fluid temperature is carried out by direct measurement via a sensor in the fluid, or indirect measurement via a sensor on the pump jacket or bleed screw or an observed quantity such as the power consumption and a fluid temperature calculation model.

Optionally, an external heat source is arranged such. B. a

Immersion heater, which accelerates the heating process. For connection of this connection, drainage nozzles are recommended on the beams or

Blind flanges / screw caps of the beams. These drainage devices also offer the hygienic advantage of being able to drain stagnant water during normal operation. Heating up, keeping the temperature, monitoring, success control,

Detection and drainage of the water are analogous to the single pump.

For a temperature control to a predetermined setpoint, a targeted operation of the centrifugal pump (s) for adjusting the detected fluid temperature can be done by two-step control by switching on and off the centrifugal pump or by speed control of the centrifugal pump by a frequency converter.

A subsequent cooling of the reaction space is carried out by draining the heated fluid and subsequent flow of cooler fluid, eg. B. by completely opening the screw. Here is also a pump-internal or

Plant internal circulation through pump internal or plant internal

Connection in the way that a heat transfer to the fluid is kept low, for. B. by an intermittent operation by turning on and off the centrifugal pump or by speed control of the centrifugal pump to low

Speeds. This has the advantage of a homogeneous temperature distribution, a uniform cooling of the entire reaction space and a simplified detection of the fluid temperature.

A storage of the detected measured values is preferably provided for the detection of the performed thermal disinfection, z. B. as a protocol with a diagram of the temperature or as a sticker with the function to prove the thermal disinfection over discoloration with sufficiently long heating.

Claims

claims

1. A method for thermal disinfection in a drinking / service water, sewage or other liquid media promotional centrifugal pump or pump system with at least one centrifugal pump, the / a opening to the suction side (11) of the centrifugal pump or the pump system suction port (13) and a to the pressure side (9) opening pressure port, characterized in that the centrifugal pump or the pump system with a closed suction port and / or closed pressure port, the medium via a pressure side (9) with the suction side (11) hydraulically temporarily short-circuiting, within the centrifugal pump or the

Pump system located compound (15) promotes circulation in such a way that the medium and thus the media-contacting parts of the centrifugal pump or the pump system are heated to a disinfecting temperature.

2. The method according to claim 1, characterized in that the medium is a specially introduced for the process medium, in particular a demineralized water or a disinfecting or cleaning solution or funded in normal operation of the centrifugal pump or the pump system medium or a mixture of both.

3. The method according to claim 1 or 2, characterized in that the temperature of the medium is detected temporarily or permanently, wherein the detection via a sensor, a calculation or a

Estimation is done.

4. The method according to any one of the preceding claims, characterized

characterized in that the operation of the centrifugal pump or the

Pump system is controlled or controlled to match the detected temperature with a predetermined target temperature.

5. The method according to any one of the preceding claims, characterized

characterized in that during the pumping in circulation, the pump with a relation to the current speed higher speed in particular at the maximum speed or up to 20 percent higher speed than the maximum speed runs.

6. The method according to any one of the preceding claims, characterized

characterized in that the operation of the centrifugal pump or the

Pump system is controlled on an at least temporarily temporally defined profile of target temperatures or temperatures recorded.

7. The method according to any one of the preceding claims, characterized

characterized in that a proof of compliance with the disinfecting effect is provided by detecting the prevalence of the disinfecting temperature over the necessary period of time.

8. The method according to any one of the preceding claims, characterized

characterized in that the detection of the influence of temperature on a material happens that changes its state due to the effect of temperature over the necessary period.

9. The method according to any one of the preceding claims, characterized

characterized in that the opening of the short-circuiting connection and the start of the control operation along the temperature profile

automated.

10. The method according to any one of the preceding claims, characterized

characterized in that the medium after heating to a disinfecting temperature for disinfecting at least one element located outside the circuit in one of the centrifugal pump or the

Pump system is forwarded downstream section, which houses the element.

11. centrifugal pump or pump system with at least one centrifugal pump with a suction side (11) of the centrifugal pump or the pump system opening suction port (13) and one to a pressure side (9)

opening pressure connection in particular according to the method according to one of the preceding claims, characterized in that within the centrifugal pump or the pump system, a pressure-side (9) with the suction side (11) hydraulically short-circuiting connection (15), in particular a connection opening or a connecting channel for opening so that by pumping the medium in the circulation, the medium is heated to a disinfecting temperature.

12. Centrifugal pump or pump system with at least one centrifugal pump according to claim 11, characterized in that in the connection (15) between the pressure and the suction side (9, 11) from the outside

actuatable shut-off device (18) is provided for opening and closing the connection.

13. Centrifugal pump or pump system with a centrifugal pump according to claim 11 or 12, characterized in that the centrifugal pump or the pump system has a measuring point for a temperature sensor having a high heat transfer from the medium to the measuring point by special design and appropriate choice of material to a

to achieve reliable measurement results.

14. Centrifugal pump according to one of claims 1 to 13, d a d u r c h

characterized in that the circulation is within the

Pump housing is located.