WO2009153030A1

WO2009153030A1 - Method for operating a mercury low-pressure lamp, a quick-start mercury low-pressure lamp and use thereof

Info

Publication number: WO2009153030A1
Application number: PCT/EP2009/004362
Authority: WO
Inventors: Alex Voronov; Karsten Ernesti
Original assignee: Heraeus Noblelight Gmbh
Priority date: 2008-06-19
Filing date: 2009-06-17
Publication date: 2009-12-23
Also published as: DE102008037250A1; EP2289290A1

Abstract

In conventional methods for operating a mercury low-pressure lamp having a lamp envelope in which two electrodes are disposed, a gas discharge is created by means of applying a constant lamp current, said discharge achieving a target value only after a certain time period. In order to provide a mercury low-pressure lamp operating mode that allows the lamp to reach full UV power after only a short period of time, the invention provides that the lamp current is significantly increased in a start phase as opposed to that of a subsequent operating phase.

Description

Patent application Heraeus Noblelight GmbH

A method of operating a low pressure mercury lamp, quick start mercury low pressure lamp and use thereof

description

The present invention relates to a method for operating a mercury low-pressure lamp with a lamp bulb, in which two electrodes are arranged and in which a gas discharge is generated by applying a lamp current.

Furthermore, the invention relates to a quick-start mercury low-pressure lamp comprising a lamp bulb, in which two electrodes are arranged and in which a gas discharge can be generated by applying a lamp current.

In addition, the invention involves the use of the quick-start mercury low-pressure lamp for sterilizing a medium, such as air, water or surfaces.

State of the art

Mercury low pressure lamps offer excellent efficiency. About 40% of the electrical power is converted to UV-C radiation at 254 nm. These lamps are used for the sterilization of air, water and surfaces. Typical fields of application are drinking water sterilization and process water treatment in industry, water disinfection in fish farming, but also desi- air in air-conditioning and cooling systems, removal of organic substances from exhaust gases, such as fume hoods, and surface disinfection.

However, conventional low-pressure mercury lamps have the disadvantage that they take a few minutes to reach full UV power. The reason for this is that mercury contained in the discharge space is still in liquid form when the lamp is switched off and for some time after ignition. In the gas phase is initially only a part of the necessary for optimal lamp operation mercury. The remainder of the gas phase consists of noble gas. Only the heating of the filling gas by the noble gas discharge brings sufficient mercury in the gaseous phase, so that the lamp reaches its expected UV power level.

The above-described operation of conventional mercury low-pressure lamps and the resulting time course of the UV-C emission are shown schematically in Figure 2. In this case, the time t [s] on the X-axis, the intensity of the UV-C emission (relative to the desired value of the UV-C intensity relative value) on the Y axis and the Z axis on the Y axis Lamp current I [A] shown. It can be seen that the lamp current is constant over time. The known mercury low-pressure lamps are operated depending on the size of the lamp at a nominal lamp current in the range of 0.2 A to 1, 0 A. The intensity of the UV-C emission gradually increases with time in a flattening curve and reaches the setpoint value after about 200 seconds, which is constant on further operation with the nominal lamp current.

Technical task

The object of the invention is therefore to provide a mode of operation for a low-pressure mercury lamp, with which the lamp reaches the full UV performance after a short time.

In addition, the invention has for its object to provide a low-pressure mercury lamp, which allows an operation in which already after a short time Switch-on time the full UV power is available. Such a "quick-start mercury low pressure lamp" is also referred to below as "quick start lamp".

The invention is further based on the object of specifying a suitable use for such a quick start lamp.

With regard to the method for operating the low-pressure mercury lamp, this object is achieved on the basis of a method of the type mentioned in the present invention, that in a starting phase of the lamp current compared to that in a subsequent operating phase is substantially increased.

The method according to the invention for operating a mercury lamp provides for a start phase preceding the actual operating phase, in which the lamp current is markedly increased in comparison to the subsequent operating phase. It has been found that such an increase results in, for example, a standard UV lamp having a starting current of approximately 2 A for 3-5 seconds at a lamp current of 425 mA. The increased lamp current ensures that despite the non-optimal vapor pressure of mercury in the radiator enough and virtually immediate UV light is produced. After 3-5 seconds, the radiator is already heated so high that the optimum vapor pressure is reached and the lamp current is reduced to normal level in the operating phase, which is at 0.2 A to 1, 0 A.

This means that the start-up time shortens from approx. 3 minutes to 0.5 seconds and thus the lamp can develop its full UV output after just half a second.

The higher the lamp current selected in the starting phase, the shorter the time until the rated power of the UV radiation is available. In the following, this duration is also referred to as the "start-up period." A substantial increase in the lamp current in the starting phase is understood as meaning an increase in the lamp current which permits a sufficient shortening of the starting time with regard to the intended use of the low-pressure mercury lamp high requirements for the shortening of the start-up period, the current in the start-up phase can be many times higher than the nominal current in the operating phase, for example at 2 to 10 times.

For most applications, however, it has proven to be advantageous if the lamp current in the starting phase has a current of 0.5 to 5 A, preferably from 1 to 3 A, more preferably at least 2 A.

The increase of the current in the mode of operation according to the invention to values within the ranges mentioned leads to comparatively moderate additional requirements for the electrical, thermal and mechanical design of the low-pressure mercury lamp.

Furthermore, it has proven to be advantageous if the starting phase has a duration of 0.5 to 60 seconds, preferably from 0.5 to 8 seconds, preferably 2 seconds or more, more preferably from 3 to 6 seconds.

The shorter the starting phase, the higher the relative current increase in the starting phase and the higher are the additional requirements for the electrical, thermal and mechanical design of the low-pressure mercury lamp. To realize a start-up phase with a duration of less than 0.5 seconds, a complex design of the lamp and the electrical control is required to prevent thermal damage. In a starting phase with a duration of more than 60 seconds, the additional effort for the shortening of the starting phase is hardly worthwhile.

The mode of operation according to the invention proves to be particularly advantageous in those low-pressure mercury lamps in which the lamp current in the operating phase has a current of 425 mA.

With regard to a rapid adjustment of the target value of the UV-C emission with at the same time as little as possible increased requirements for the thermal stability of the electrodes of the lamp, it has proved to be advantageous if the current of the Lamp current in the starting phase in the range of 2 to 10 times, preferably in the range of 3 to 5 times, the current level in the operating phase.

In a preferred procedure, it is provided that the starting phase comprises a preheating phase for heating at least one of the electrodes by applying heating current.

In the case of hot cathode lamps, the electrodes can be heated by means of an additional heating current. The electrodes are often designed as heating coils. In the start phase, the electrodes are first flowed through by the heating current in order to heat them. The heating current for heating the electrodes is not part of the lamp current in the sense of the invention.

The usual duration of the preheating phase is in the range of seconds and may thus be longer than is desirable for operation of the quick-start lamp in the sense of the invention.

The excessive lamp current is in any case withdrawn in the operating phase in order to limit or prevent overheating of the low-pressure mercury lamp and a concomitant drop in power.

With regard to the quick-start mercury low-pressure lamp, the above-mentioned technical problem starting from a quick-start lamp of the type mentioned is inventively achieved in that the electrodes with a current of 1, 0 to 5.0 A, preferably from 1, 5 to 4.0 A. are operable.

The mercury low-pressure lamp according to the invention is equipped with electrodes which withstand an increased lamp current during a starting phase. The quick start lamp is suitable for carrying out the method according to the invention explained above. This means that a control device is provided, by means of which the lamp current is increased in a starting phase compared to that in a subsequent operating phase, and that the electrodes are operable in the starting phase with a higher lamp current than in the subsequent operating phase. Advantageously, by means of the control device, the lamp current in the starting phase with a current of 0.5 to 5 A, preferably from 1 to 3 A, more preferably 2 A or more, adjustable.

The electrodes of the quick-start lamp according to the invention are preferably designed such that they withstand a lamp current in the starting phase of 1, 0 A to 5.0 A preferably 1.5 to 4.0 A. This amperage is necessary to achieve as fast as possible the full UV performance of the mercury low pressure lamps. After reaching the optimum vapor pressure of mercury, the mercury low-pressure lamp according to the invention is operated in the operating phase, which are usually 0.2 A to 1, 0 A.

The quick start lamp according to the invention is thus able to withstand higher currents for brief moments and thus to reach the normal operating state much faster.

Advantageous embodiments of the quick-start lamp will become apparent from the Unterans- prüchen. Insofar as specified in the dependent claims embodiments of the quick start lamp are recited in the subclaims for the method according to the invention mentioned procedures, reference is made for additional explanation to the above statements on the corresponding method claims.

UV-C radiation is particularly suitable for killing microorganisms. Therefore, mercury low pressure lamps are known to be extensively used for the sterilization of liquids such as drinking or waste water, gases, such as in air conditioners or in fume hoods or for the sterilization of man-made waters and drinking water and for sterilizing the air, such as in air conditioners or the exhaust air of fume hoods and of surfaces such as in germ-sensitive medical fields or filters and the like. In the quick-start lamp according to the invention, the nominal UV power is available in a particularly short time after switching on. Therefore, the above-mentioned object with regard to the use of the quick-start lamp according to the invention is achieved in that the quick start lamp is used as part of a switchable system, wherein the quick start lamp is started by switching on the system and simultaneously a relative movement between the medium and the quick start lamp for the purpose of sterilization is generated.

The relative movement between the medium to be sterilized and the quick-start lamp is generally carried out by movement of the medium, for example by a flow of a gaseous or liquid medium, along the lamp.

The system can be, for example, a drinking water supply system or an air purification system. In the former case, the quick start lamp is part of the drinking water supply system and is used in the context of this system so that at the same time the mercury low-pressure lamp according to the invention is turned on by switching on the drinking water supply and the flow of drinking water. The fact that the lamp provides the required for sterilization UV-C power after a short time, the passage of not or insufficiently sterilized drinking water is minimized.

The same applies to the use of mercury low-pressure lamp according to the invention in a fume hood of an air purification system.

Working Example

The invention will be explained in more detail with reference to an embodiment and a drawing. This shows in a schematic representation

1 shows a diagram with the time profile of the power supply and the resulting time course of the UV-C emission in a low-pressure mercury lamp according to the invention, Figure 2 is a diagram showing the time course of the power supply and the resulting time course of the UV-C emission in a conventional mercury low-pressure lamp, and

Figure 3 shows an embodiment of the quick start lamp according to the invention in the form of a low-pressure mercury lamp with optional preheating the

Wendel.

In the diagram of Figure 1 are on the X-axis time t [s], on the Y-axis, the intensity of the UV-C emission (relative to the target value of the UV-CI intensity relative value) and on the Z-axis the lamp current I [A] is shown.

It can be seen that the lamp current rises to 2 A immediately after switching on the lamp. As a result, there is also a very rapid increase in the intensity of UV-C emission within about 0.5 seconds to the set point. In the case of the quick-start lamp according to the invention, the start-up phase is thus significantly shortened, so that the lamp can already develop its full UV-C power after about half a second. After about 2 s, the lamp current is reduced to the nominal value of 0.425 A. As a result, the intensity of the UV-C emission no longer changes and remains constant over time.

The quick start lamp is used to disinfect the water in a drinking water supply system. It is used in such a way that it is switched on immediately when the drinking water supply is started up. Since the lamp provides the required for sterilization UV-C power after a short time, the passage of not or insufficiently sterilized drinking water is minimized.

An embodiment of the quick start lamp according to the invention is explained in more detail below with reference to FIG. FIG. 3 schematically shows the ends of the discharge space 7 of a low-pressure mercury lamp 1 (represented by a broken line), which has a nominal power of 10 W (with a nominal lamp current of 425 mA), a radiator length of 20 cm and thus a power density of approximately 0 , 5 W / cm. It consists of a quartz glass tube 4 attached to its Ends with bruises 2 is closed, are embedded in the molybdenum foils 3 and the ends of metallic terminals to a helical electrode 5a, 5b. For this purpose, the electrodes 5a, 5b have "legs" 6, which are connected to the molybdenum foil 3. Between the electrodes 5a, 5b, an arc is generated during operation.

To facilitate the work function, the electrodes 5a, 5b are provided with an emitter paste, which is fixed by means of a basket wire. In order that the helical electrodes 5a, 5b located opposite the discharge space 7 withstand the increased lamp current during the starting phase, the diameters of wicker wire and electrode wire are reinforced, so that these components withstand a current of 2 A.

The power supply of the low-pressure mercury lamp 1 comprises a first circuit "A" which serves to heat the electrodes 5a, 5b and which is referred to herein as a "heating current circuit". In addition, the power supply of the low-pressure mercury lamp 1 comprises a second circuit "B", which serves to apply the lamp current and which is referred to below as the "lamp circuit". The circuits "A" and "B" are part of a control device 8.

Immediately after switching on the lamp 1, a lamp current of 2 A is set, as shown in the diagram of Figure 1.

The lamp current, which is increased from the usual value of 0.425 A, is maintained during a 2 second start-up phase. This results in a rapid increase of the UV-C emission to a setpoint value corresponding to the lamp type (as shown in FIG. 1). Subsequently, the control device 8 reduces the increased lamp current to the nominal lamp current in the operating phase (425 mA) in order to prevent excessive heating of the lamp 1 and damage to the electrodes 5a, 5b.

Additionally or alternatively, the quick start lamp according to the invention can also be operated as a hot cathode lamp by during a preheat on the electrodes 5a, 5b via the circuit "A" an additional heating current is passed, which leads to an increase in temperature of the electrodes 5a, 5b.

Claims

claims

1. A method for operating a low-pressure mercury lamp with a lamp bulb (4), in which two electrodes (5a, 5b) are arranged and in which by applying a lamp current (B), a gas discharge is generated, characterized in that in a start phase of Lamp current (B) compared to that in a subsequent operating phase is substantially increased.

2. The method according to claim 1, characterized in that the lamp current (B) in the starting phase has a current of 0.5 to 5 A, preferably from 1 to 3 A, more preferably at least 2 A.

3. The method according to claim 1 or 2, characterized in that the starting phase has a duration of 0.5 to 60 seconds, preferably from 0.5 to 8 seconds, preferably 2 seconds or more, more preferably from 3 to 6 seconds.

4. The method according to any one of the preceding claims, characterized in that the lamp current (B) in the operating phase has a current of 425 mA.

5. The method according to any one of the preceding claims, characterized in that the current intensity of the lamp current (B) in the starting phase in the region of

2- to 10-fold, preferably in the range of 3 to 5 times, the current in the operating phase is.

6. The method according to any one of the preceding claims, characterized in that the start phase comprises a preheating phase for heating at least one of the electrodes (5a, 5b) by applying heating current (A).

7. The method according to claim 6, characterized in that the lamp current (B) in the preheating phase relative to the lamp current (B) is increased in the subsequent operating phase.

8. rapid-start mercury low-pressure lamp, comprising a lamp bulb (4) in which two electrodes (5a, 5b) are arranged and in which a gas discharge can be generated by applying a lamp current (B), characterized in that the electrodes (5a, 5b) with a current strength of 1, 0 to 5.0 A, preferably from 1.5 to 4.0 A are operable.

9. low-pressure mercury lamp according to claim 8, characterized in that a control device (8) is provided, by means of which the lamp current (B) is increased in a starting phase compared to that in a subsequent operating phase, and that the electrodes (5a, 5b) in the starting phase can be operated with a higher lamp current (B) than in the subsequent operating phase.

10. low-pressure mercury lamp according to claim 9, characterized in that by means of the control device (8) of the lamp current (B) in the starting phase with a current of 0.5 to 5 A, preferably from 1 to 3 A, more preferably at least 2 A, adjustable is.

11. low-pressure mercury lamp according to one of claims 9 or 10, characterized in that by means of the control device (8) has a duration of the starting phase of 0.5 to 60 seconds, preferably from 0.5 to 8 seconds, preferably 2 seconds or more, more preferably from 3 to 6 seconds, is adjustable.

12. low-pressure mercury lamp according to one of claims 9 to 11, character- ized in that by means of the control device (8) of the lamp current (B) in the operating phase to a current of 425 mA is adjustable.

13. low-pressure mercury lamp according to one of claims 9 to 12, characterized in that by means of the control device (8) the current intensity of the lamp current (B) in the starting phase in the range of 2 to 10 times, preferably in the range of 3- to 5 times, the current is in the operating phase.

14. Mercury low-pressure lamp according to one of claims 9 to 13, characterized in that by means of the control device (8) a start phase is adjustable, which comprises a preheating phase for heating at least one of the electrodes (5a, 5b by applying heating current (A).

15. Mercury low-pressure lamp according to claim 14, characterized in that the control device (8) is adjustable such that the lamp current (B) is increased in the preheating phase with respect to the lamp current (B) in the subsequent operating phase.

16. Use of the quick-start mercury low-pressure lamp according to one of claims 8 to 15 for disinfecting a medium, such as air, water or surfaces, characterized in that the quick-start lamp is used as part of a switchable system, wherein by switching on the system, the quick start lamp is started and at the same time a relative movement between the medium and the quick start lamp for the purpose of sterilization is generated.