EP2663740A1

EP2663740A1 - Turbine cleaning

Info

Publication number: EP2663740A1
Application number: EP12700228.5A
Authority: EP
Inventors: Gerd Mundinger; Joel Schlienger; William Gizzi; Martin Eckert
Original assignee: ABB Turbo Systems AG
Current assignee: Accelleron Industries AG
Priority date: 2011-01-14
Filing date: 2012-01-11
Publication date: 2013-11-20
Also published as: WO2012095434A1; KR20130117851A; DE102011008649A1; JP2014503046A; CN103314186A; JP5840701B2; CN103314186B; US20130298944A1

Abstract

A cleaning method is disclosed for wet cleaning of an exhaust-gas turbine. An amount of cleaning fluid injected via a nozzle into the flow duct of the turbine can be variable over a course of time about a defined mean amount of cleaning fluid.

Description

Turbine cleaning

DESCRIPTION

Technical area

The invention relates to the field of turbomachines subjected to exhaust gases of internal combustion engines. It relates to a cleaning method for cleaning an exhaust gas turbine and a cleaning device for cleaning a turbines acted upon by exhaust gases of an internal combustion engine by means of such a cleaning method.

Exhaust gas turbines are used in exhaust gas turbochargers for charging internal combustion engines or in power turbines for converting the energy contained in the exhaust gases of internal combustion engines into mechanical or electrical energy.

Depending on the actual operating situation and the composition of the fuels used to drive the internal combustion engine, sooner or later fouling of the turbine blades of the impeller, the guide vanes of the nozzle ring and the various turbine housing parts will occur in the exhaust gas turbine. Such dirt deposits lead in the region of the nozzle ring to a poorer turbine efficiency and consequently to reduce the performance of the following machines, for example the compressor driven by the exhaust gas turbine and the supercharged internal combustion engine itself. As a result, there is an increase in exhaust gas temperatures in the combustion chamber, whereby both the internal combustion engine as well as the turbocharger can be thermally overstressed. In particular, damage or even destruction of the exhaust valves can occur in the internal combustion engine.

If a dirt layer is deposited on the nozzle ring and on the turbine blades of a turbocharger connected to a four-stroke internal combustion engine, an increase in the turbocharger speed and consequently in the boost pressure and the cylinder pressure must also be expected. As a result, both components of the internal combustion engine and the turbocharger in addition to the increased thermal stress and mechanically higher claimed, which can also lead to the destruction of the affected components. With irregular distribution of the dirt layer on the circumference of the blades of the turbine wheel, there is an increase in the imbalance of the rotor, whereby the storage can be damaged.

If there are dirt deposits on the turbine housing at the outer contour of the flow channel extending radially outside the turbine blades, contact may occur during operation due to the reduced radial play between turbine blades and turbine housing which can damage the turbine blades and make them useless in extreme cases.

Therefore, the nozzle ring, turbine blades and affected areas of the turbine housing must be regularly cleaned during operation of any adhering dirt. This is typically done through the use of dry or wet cleaning systems.

Wet cleaning systems are characterized in that during a cleaning cycle by means of one or more nozzles, which are positioned on the turbine inlet side, a liquid detergent, such as cold water, is injected. By introducing cold cleaning liquid onto hot soiling deposits, they are removed and the surfaces are restored to almost their original state upon delivery. The injection of cold cleaning liquid onto the hot turbine components, however, represents a comparatively high thermomechanical load on the turbine components. In order to avoid resulting damage to the components of the turbine, the turbine wet cleaning is usually only at low engine loads - with correspondingly low gas inlet temperatures at the turbocharger - allowed. The cleaning cycle is therefore typically designed to reduce the load on the engine to a level suitable for the cleaning cycle (e.g., 25% of normal engine load) and to inject cleaning fluid after a hold time for a defined period of time (eg, 10 minutes). Subsequently, during a further period of time (for example 10 minutes) any cleaning fluid present in the turbocharger is evaporated before the engine is then brought back to its normal load level.

The injection of cleaning fluid during the cleaning cycle through one or more nozzles before turbine entry usually takes place under constant pressure and constant flow instead. The injection nozzles are designed such that they produce a distribution of cleaning liquid which can wet a specific surface area of the nozzle ring or of the turbine housing with cleaning liquid per nozzle. The impinging distribution of cleaning fluid on the surfaces is dependent on several factors such as the flow state in front of the turbine, the jet shape generated by the nozzle orifice of the nozzles, the injection pressure and the amount of cleaning fluid, the turbine inlet temperature, etc.

The design of the nozzles is carried out at a defined load point, known flow variables and constant cleaning system sizes. In actual engine operation, the above-mentioned influencing variables can deviate greatly from the variables used in the original design, which in turn alters and even reduces the surface areas wetted in real operation, which can lead to unsatisfactory cleaning results.

The point in time at which a cleaning cycle is to be initiated can either be made permanently dependent on the operating time, for example fixed cleaning intervals after a certain number of operating hours, or contamination indicators can be detected, which then automatically trigger a cleaning cycle.

State of the art

DE 35 15 825 A1 discloses a method and a device for cleaning the rotor blades and the nozzle ring of the axial turbine of an exhaust gas turbocharger. The cleaning device consists of several arranged on the gas inlet housing of the axial turbine nozzles that extend into the flow channel and a supply line for cleaning fluid. At a certain degree of contamination of the axial turbine, a cleaning requirement is determined via a measuring and evaluation unit. Accordingly, cleaning liquid is injected into the flow channel via the nozzles arranged upstream of the guide vanes. The resulting droplets are transported from the exhaust stream to the guide and the blades of the axial turbine and clean them of the adhering dirt. During a relatively short cleaning interval, a large amount of cleaning fluid (about 3-5 l / min cleaning fluid per m ³ / s of exhaust gas) is fed into the flow, in order to achieve the most thorough possible cleaning. In this cleaning process must be due to the large amount of cleaning fluid, the engine load can be reduced early and throughout the cleaning process. This is necessary to avoid an unacceptably high increase in exhaust gas temperatures during the cleaning process. An excessive increase in the exhaust gas temperatures during the cleaning process leads to thermal overload of the exhaust gas turbine and the internal combustion engine.

It is also known from the prior art that in the initial phase of the injection of a cold cleaning liquid in a high amount (see above) onto the hot guide vanes of the nozzle ring and blades of the turbine wheel, an additional thermal shock cleaning effect can be achieved. Not only the guide vanes of the nozzle ring and the blades of the turbine wheel, but also the turbine housing parts are thermally stressed during thermal shock cleaning. The avoidance of the formation of impermissibly high thermal stresses or even cracks in the corresponding components is structurally very complicated, requires a sophisticated control of cleaning and thereby causes high costs.

From WO2007 / 036059A1 a cleaning method for wet cleaning an exhaust gas turbine is known in which continuously or clocked a small amount of cleaning liquid is fed into the exhaust gas flow of an exhaust gas turbine and fed to the components of the exhaust gas turbine to be cleaned. The small amount of cleaning liquid can be fed with unchanged engine operation, so that the cleaning or keeping clean the exhaust gas turbine can be carried out throughout the engine operating range. Fluctuations in the power output of the internal combustion engine due to become necessary exhaust gas turbine cleaning should thus be avoided. Furthermore, the formation of thermal stress cracks in the turbine housing parts which are particularly at risk in this respect should be able to be largely avoided.

Fl 1 17 804 discloses a cleaning device for wet cleaning an exhaust gas turbine, wherein the pressure of the cleaning liquid statically fixed, about 2 bar above the pressure of the exhaust gases in the flow channel is. In order for wet cleaning to be carried out at full load, part of the cooler fresh air is supplied to the exhaust gas flow from the compressor outlet. As a result, the temperature of the exhaust gas stream lowers to an optimal, for the cleaning of the turbine parts, predetermined value. From EP1972758A1 a cleaning method for wet cleaning of an exhaust gas turbine is known, in which operating point independent cleaning liquid is fed into the exhaust gas stream of the exhaust gas turbine and fed to the components of the exhaust gas turbine to be cleaned. In this case, the injection pressure of the cleaning liquid is adapted to the conditions upstream of the exhaust gas turbine. For this purpose, in a first step, at least one measured value characterizing the conditions prevailing in front of the turbine is measured, in a second step, a value for the injection pressure of the cleaning liquid is determined from the measured quantity measured, and in a third step

Cleaning liquid injected with the specific injection pressure in the flow channel

Brief description of the invention

The object of the present invention is to provide a cleaning method for wet cleaning of an exhaust gas turbine, with which a possible full-surface wetting of the dirty turbine parts can be realized.

According to the invention this is achieved by a transient injection of cleaning liquid by the amount of cleaning liquid injected via a nozzle into the flow channel of the turbine varies over time by a certain, average amount of cleaning liquid.

The generation of the temporally variable amount of cleaning fluid (periodic, aperiodic, random course) can be effected for example by influencing the injection pressure or the amount of cleaning fluid, such as a pump with adjustable flow, a controllable valve in the supply line or oscillating flow elements in front of the nozzle , or by influencing the size of the nozzle opening, such as regulated iris diaphragms or controlled or free-oscillating nozzle opening flaps. The variation of the amount of cleaning fluid is carried out by a certain mean, wherein the time-variable course can optionally be periodic, aperiodic or random.

When varying the injection pressure, for example, the determined, average injection pressure due to the geometrical dimensions of the exhaust gas turbine, or dynamically determined as a function of the respective operating point of the exhaust gas turbine and / or the respective operating point of the internal combustion engine. The variation of the amount of cleaning liquid is advantageously realized by an automatic injection pressure control, or by a control for the nozzle opening.

If the injection pressure is varied transiently, the generated distribution of cleaning fluid and thus the wetting of the turbine surfaces change, even with otherwise constant cleaning system sizes. The advantage thus gained is that, by varying the amount of cleaning liquid, the distribution of cleaning liquid and the surface wetting can be varied transiently over an adjustable surface area and a better cleaning effect is achieved independently of the respective individual flow state in the turbocharger.

Optionally, the variation of the quantity of cleaning liquid in the case of two or more nozzles distributed along the circumference can be realized differently from one another, such that over time different, or staggered courses of the quantities of cleaning liquid result. Optionally, the injected total amount of cleaning liquid can be kept constant

Brief description of the drawings

Subsequently, the cleaning method according to the invention is described in more detail with reference to figures. This shows

Fig. 1 is a sectional view of an exhaust gas turbocharger with a turbine side

Cleaning device

Fig. 2 is a diagram showing the course of the amount of cleaning liquid over the

Time, as well as the schematically illustrated effect of the variance of the amount of cleaning fluid on the wetting of the turbine housing parts,

Fig. 3 shows two diagrams with the course of injection pressure and amount of

Cleaning fluid over time,

Fig. 4 is a diagram of a first embodiment of a cleaning device for

Carrying out the cleaning method according to the invention with a variable pump with adjustable flow, a diagram of a second embodiment of a cleaning device for carrying out the inventive cleaning method with an adjustable valve in the supply line,

a diagram of a third embodiment of a cleaning device for carrying out the inventive cleaning method with an adjustable flow divider,

a diagram of a fourth embodiment of a cleaning device for performing the inventive cleaning method with individually adjustable nozzle openings, and

another diagram with the course of amount of cleaning fluid over time.

Way to carry out the invention

Fig. 1 shows a sectional view of an exhaust gas turbocharger with an exhaust gas turbine (right) and a compressor. The exhaust gas turbine comprises a turbine wheel 2 with rotor blades 21, which turbine wheel is arranged in a turbine housing 20. Via a shaft 3, which is rotatably mounted in a bearing housing 30, the turbine wheel is connected to the compressor wheel 1. The compressor wheel is arranged in the compressor housing 10.

In the region of the turbine inlet, in which hot exhaust gas from the annular cavity-shaped collecting channel flows through the narrow flow channel onto the rotor blades 21 of the turbine wheel 2, the turbine has a nozzle (nozzle ring with vanes) 22, which aligns the exhaust gas flow to the rotor blades of the turbine wheel. The flow channel in this area limiting wall parts of the turbine housing and the guide vanes of the diffuser are, as described above, exposed to pollution by deposition.

Immediately upstream of the turbine inlet, the exhaust gas turbine on a cleaning device, which has an annular channel 41 for supplying the cleaning liquid and one or more nozzles 42 for injecting the cleaning liquid into the collecting and flow channel of the turbine.

Depending on the type of turbine (axial, mixed flow or radial turbine) and / or the design of the turbine, the exact arrangement of the cleaning device may vary. Typically, however, the nozzles are always mounted upstream of the guide, so that the flow of the hot exhaust gas carries the cleaning liquid and distributed to the surfaces to be cleaned. The nozzles 42 are advantageously distributed along the circumference of the turbine housing, wherein the number of nozzles can be matched to the number of vanes of the nozzle. For example, one nozzle may be provided for each vane or one nozzle for each two vanes. Optionally, additional nozzles can be provided independently of the distributor, which are directed approximately directly onto the walls of the flow channel.

If a cleaning cycle is to be initiated due to the fact that a certain number of operating hours have been reached or, as a contamination indicator indicates the need for cleaning, a hot cleaning fluid is fed to the hot exhaust gas flow upstream of the guide device and the rotor blades of the turbine wheel. The cleaning liquid, usually water or water added with a cleaning-promoting substance, is injected into the flow channel in controlled quantities and at a certain pressure. According to the invention, the amount and / or the injection pressure is varied transiently, so that according to FIG. 2, depending on the amount and / or injection pressure, different areas of the surfaces to be cleaned are wetted with the cleaning liquid.

In FIG. 2, the effect of the respective injection pressure on the spray pattern of the cleaning liquid is shown schematically for three points on the indicated course of the periodically varied injection pressure p _w over the time t. In the left part of the figure, a mean injection pressure is shown, in which the jet emitted from the nozzle into the flow is deflected by the flow onto the middle region of the guide device. At higher pressure, shown in the middle part of the figure, the jet from the nozzle extends to the far edge of the flow channel, while at lower pressure, in the right part of the figure, only the right inner edge portions of the vanes are wetted.

The unsteady variation of the amount of cleaning fluid and / or the injection pressure according to the invention is effected by an average value, ie by a specific, average amount of fluid or an average injection pressure, and within a one- or two-sided limited range between a minimum value and / or a maximum value. These mean, minimum and maximum values can either be fixed due to the Turbine geometry and the intended flow conditions may be predetermined, or they can be dynamically adjusted to the flow conditions upstream of the turbine - in particular the exhaust gas pulse stream - and / or the engine load. In the second case, for example, at the beginning of a cleaning interval, the specific mean values to be applied could be calculated on the basis of defined characteristic curves or read from a table as a function of one or more turbine or engine-specific measured variables. The turbine- or engine-specific measured quantities can be determined in various ways. Engine-specific measurement data, such as load lever position or injection parameters, can be evaluated and the engine load derived therefrom. If the engine further units, such as a power generator, followed, the engine load can be measured directly at this downstream unit. Also, specific measurement data of the turbocharger can be evaluated, for example, the turbocharger speed. Since the design of the turbocharger is usually known, the gas mass flow or the gas volume flow, and thus the state upstream of the turbine, can be approximately determined with the aid of the TL speed from the corresponding characteristic diagrams. Furthermore, it would be possible to measure the gas flow directly in the flow channel, for example by means of a hot-wire, ultrasonic or laser Doppler anemometer. Detailed information on determining the turbine- or engine-specific parameters can be found in EP1972758A1.

The variation of the amount of the cleaning liquid m ^* _w and / or the injection pressure p _w , as indicated schematically in the diagrams of FIG. 3, periodically (curve b, dotted), aperiodic or quite randomly (curve c, solid) around the middle Injection pressure (curve a, dashed) or the average injection quantity done. With changing injection pressure (upper diagram) and otherwise constant conditions, the amount of the injected cleaning liquid m ^* _w (lower diagram) follows the course of the injection pressure p _w . FIG. 8 shows a further example of a periodic progression of the amount of the cleaning liquid m ^* _w injected, in which the instantaneous quantity of the cleaning liquid per nozzle temporarily assumes the value zero within a period of time. A cleaning cycle usually comprises several periods of 3-120 s duration, wherein the total duration of each cleaning cycle may be fixed, or may depend on the current contamination of the components of the turbine and / or the number of operating hours since the last cleaning cycle , If the cleaning device comprises two or more nozzles distributed along the circumference, the inventive cleaning method can optionally be carried out such that the total liquid quantity of all nozzles remains constant over time within the cleaning cycle and corresponds to the determined average quantity of liquid multiplied by the number of nozzles. On the other hand, the amount of cleaning fluid injected per nozzle into the flow channel of the turbine varies over time by the specific average quantity of fluid during the cleaning cycle.

How the time-variable amount of cleaning liquid per nozzle is controlled is shown by way of example and schematically in FIGS. 4 to 7 with reference to various embodiments of cleaning devices:

4 shows a first embodiment of a cleaning device for cleaning a turbine acted upon by exhaust gases of an internal combustion engine by means of the inventive cleaning method with a pump 431 with adjustable flow. The pump can be controlled via an electronic control unit 5, with or without feedback of the currently set flow rate.

Fig. 5 shows a second embodiment of such a cleaning device with a pump 43, which conveys a constant amount of cleaning liquid, and with a valve 44 with adjustable flow in the supply line between the pump 43 and the nozzles 42. With these first two, simple embodiments several nozzles 42 can not be controlled individually, unless pump and / or valve would be two or more times side by side.

Fig. 6 shows a third embodiment with a pump 43, which conveys a constant amount of cleaning liquid, and an adjustable flow distributor 45, which electronically or mechanically controlled, the amount of cleaning liquid, which is passed to the various nozzles 42 varies. In this embodiment, it is possible to individually vary the amount of cleaning liquid from nozzle to nozzle while keeping the total amount of cleaning liquid constant. This is likewise possible with the fourth embodiment according to FIG. 7, in which the individual nozzles 421 have adjustable nozzle openings, for example adjustable iris diaphragms or adjustable or freely oscillating nozzle opening flaps. These four embodiments presented can be combined with each other and / or combined with other elements for adjusting injection pressure and / or flow rate.

Instead of the described, electronically controlled control unit and mechanical controls, for example, oscillating flow elements or rotating flaps, be provided to vary the flow through a supply line or the distribution between the individual leads to the nozzles.

LIST OF REFERENCE NUMBERS

1 compressor wheel

10 compressor housing

2 turbine wheel

20 turbine housing

21 blades of the turbine wheel

22 diffuser (nozzle ring with vanes)

3 shaft of the turbocharger

30 bearing housing

41 channel for supplying the cleaning fluid

42 nozzles for injecting the cleaning fluid

421 nozzles with adjustable nozzle openings

43 Pump for the cleaning fluid to be injected

431 Variable pump with adjustable flow

44 Adjustable valve in the supply line of the cleaning fluid

45 Adjustable flow divider in the supply line of the cleaning fluid 5 Control unit

p _w injection pressure of the cleaning fluid

m ^* w Amount of cleaning fluid injected

a Injection curve with constant injection pressure b Injection curve with periodically changing injection pressure c Injection curve with randomly changing injection pressure t Time

Claims

P AT EN TA NSPR O CHE

A cleaning method for cleaning an exhaust gas of an internal combustion engine

acted upon turbine, the exhaust gases in a flow channel on the

Blades of a turbine wheel are guided

in which cleaning method in a cleaning cycle, a cleaning liquid is injected into the flow channel via at least one nozzle,

characterized,

that the amount of cleaning fluid injected into the flow channel of the turbine per nozzle increases by one within the cleaning cycle over time

certain, average amount of liquid is varied.

2. A cleaning method according to claim 1, wherein the specific, middle

Liquid quantity is determined due to the geometric dimensions of the turbine.

A cleaning method according to claim 1, wherein said specific, middle

Liquid quantity depending on the flow channel in front of the turbine

in a first step, at least one measured variable characterizing the conditions prevailing in front of the turbine is measured in a second step from the measured one

Measured a value for the specific, average amount of liquid is determined, and in a third step, the cleaning fluid over time within the

Cleaning cycle varying by the specific, average amount of liquid

is injected.

4. Cleaning method according to claim 3, wherein for determining the im

Flow channel before the turbine prevailing conditions, measured variables of the internal combustion engine are measured.

5. Cleaning method according to claim 3, wherein for determining the im

Flow channel before the turbine prevailing conditions, measured variables of the exhaust gas turbocharger.

A cleaning method according to claim 1, wherein, over two or more nozzles distributed along the circumference, a cleaning liquid is introduced into the

Flow channel is injected, wherein the amount of injected per individual nozzle in the flow channel of the turbine cleaning fluid over time within the cleaning cycle is varied by a certain average amount of liquid, the total liquid volume of all nozzles over time within the

Cleaning cycle, however, remains constant and that with the number of nozzles

multiplied by a specific, average amount of liquid.

7. A cleaning method according to any one of claims 1 to 6, wherein the amount of pro

Nozzle in the flow channel injected cleaning liquid over the

Injection pressure of the cleaning liquid is controlled.

8. A cleaning method according to any one of claims 1 to 6, wherein the amount of pro

Nozzle in the flow channel injected cleaning fluid over the

Nozzle geometry is controlled.

A cleaning method according to any one of claims 1 to 8, wherein the amount of pro

Nozzle is injected into the flow channel injected cleaning fluid periodically.

10. A cleaning method according to claim 9, wherein the period is between 3 and 120 s.

1 1. Cleaning method according to one of claims 9 or 10, wherein the instantaneous

Quantity of cleaning fluid per nozzle within a period temporarily takes the value zero.

A cleaning apparatus for cleaning a turbine loaded with exhaust gases of an internal combustion engine by a cleaning method according to any one of claims 1 to 11, comprising a pump (43, 431) for conveying a cleaning liquid, at least one nozzle (42, 421) for injecting the cleaning liquid the flow channel of the turbine, as well as at least one adjustable element (421, 431, 44, 45) for dynamically varying the flow of the cleaning liquid.

13. Cleaning device according to claim 12, wherein as adjustable element, a pump (431) is provided for conveying the cleaning liquid with adjustable flow rate.

14. Cleaning device according to claim 12, wherein as an adjustable element

adjustable valve (44) is provided in the supply line of the cleaning liquid to the nozzles (42).

15. Cleaning device according to claim 12, comprising two or more nozzles (42), wherein an adjustable flow divider (45) is provided in the feed line of the cleaning liquid to the nozzles (42) as an adjustable element.

16. Cleaning device according to claim 12, wherein as the adjustable element

at least one nozzle (421) is provided with an adjustable nozzle openings or a regulated iris diaphragm or an oscillating nozzle opening flap.

17. Cleaning device according to claim 12, wherein as an adjustable element

Is provided oscillating flow element in the supply line to the at least one nozzle (42).