CLIAMS:We claim:
1. A kit for cleaning a rotating wind turbine comprising:
a carriage;
a plurality of guns for misting water on the rotating turbine blades such that the axis of each of the guns is normal to a plane of the wind turbine rotor, the guns positioned at predefined heights relative to height of a tower of the wind turbine, the guns receive compressed water from the a first tank;
a first imaging device, a second imaging device for monitoring a pattern of misting fluid on the rotating turbine blades;
a plurality of sensors for monitoring direction of the wind and to maintain position of the turbine rotor in a predefined direction; and
a removable carriage positioned over a predefined height relative to the ground including the plurality of guns, a compressor, a motor and the first tank.
2. The kit for cleaning a rotating wind turbine of claim 1, wherein the first tank is replaceable by a second tank that is approximately identical to the first tank.
3. The kit for cleaning a rotating wind turbine of claim 1, wherein the first imaging device positioning on the back of the turbine blade at a predefined position relative to the tower.
4. The kit for cleaning a rotating wind turbine of claim 1, wherein the second imaging device positioning in close proximity with the bottom end of the tower.
5. A process for cleaning a rotating wind turbine using a kit for cleaning the rotating wind turbine comprising steps of:
i) ensuring if the turbine is running in a standard operation mode;
ii) monitoring speed of the wind by a plurality sensors to check if the wind speed at wind turbine location is less than 10 m/s;
iii) predicting the wind speed for a predefined amount of time;
iv) positioning the crane on the ground at a predefined safe distance relative to the tower;
v) positioning and locking a carriage at a predefined altitude and for a predefined amount of time;
vi) spraying the mist from one or more guns on a rotating turbine blade for a predefined amount of time; and
vii) replacing the first water tank by an approximately identical second water tank which is already filled with water.
6. The process for cleaning a rotating wind turbine of claim 5, wherein the altitude of the carriage is fixed according to the relation between the height ‘H’ of the tower, and the rotor diameter ‘D’ of the present invention.
7. The process for cleaning a rotating wind turbine of claim 5, wherein the future speed is predicted on the basis of the historical data acquired by the sensors over time.
8. The process for cleaning a rotating wind turbine of claim 5, wherein monitoring wind turbine speed includes checking that the turbine is not stagnant.
9. The process for cleaning a rotating wind turbine of claim 5, wherein the safe distance is (D/2+10m) in the centre line from the nacelle for ensuring the safety of technicians on the crane and turbine blades, in case there is a sudden shift of wind direction.
10. The process for cleaning a rotating wind turbine of claim 5, wherein the altitude of the carriage is fixed according to the relation between the height ‘H’ of the tower, and the rotor diameter ‘D’ of the present invention.
Dated this 06th day of November, 2014

FOR SUZLON ENERGY LIMITED
By their Agent

(GIRISH VIJAYANAND SHETH) (IN/PA 1022)
KRISHNA & SAURASTRI ASSOCIATES
,TagSPECI:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See section 10, Rule 13]

A CLEANING KIT AND PROCESS FOR CLEANING ROTATING WIND TURBINE BLADES;

SUZLON ENERGY LIMITED, A REGISTERED COMPANY UNDER THE LAWS OF INDIA WHOSE ADDRESS IS ONE EARTH, OPPOSITE MAGARPATTA CITY, HADAPSAR PUNE – 411028, MAHARASHTRA, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF INVENTION
The present invention relates to a process for cleaning the rotating wind turbines and more particularly to a process for cleaning blades of the wind turbines by throwing misting liquid on the wind turbine blades at a predefined distance from the wind turbine and from a predefined height relative to the ground.
BACKGROUND OF PRIOR ART
Maintenance of wind turbine blades is one of the important activity post installation of the wind turbines. The blades are usually clean and dirt free when the wind turbine is installed. The performance is also optimal after the installation. Many of these wind turbines around the world are located in the environments which -overtime promote debris accumulation on the blades. It is observed that the debris is usually a mixture of insects splattering and the dust present in the adjoining area. The debris accumulated on the blade gradually sticks on the blades, until the rain washes it away or is cleaned manually by the maintenance technicians.
This debris on the blades interferes with the aerodynamic efficiency of the wind turbine blades and is detrimental to the energy production of the wind turbines. It is observed that there is an average 5% of loss in energy every year. This translates into large revenue loss. This loss is multiplied incase of wind farm, where there are hundreds of such turbines installed. The available techniques for cleaning of blades of wind turbine require wind turbine to be stopped and then cleaning process is carried out by the manual method.
The cleaning process involves installing various mechanisms and also there is need of a technician to get an access to the blade. Later they are cleaned manually with the help of scrubber and water. The other known methods are accessing them through crane, sky-lift or ropes turning the blades into an appropriate position and then cleaning. All these activities are highly time consuming. One has to shut down the wind turbine for considerable time of period for cleaning maintenance, which results in the loss of generation of power too. Also, the cost of equipment used for accessing the blade and the number of man-hours used by technician makes this process very time consuming and expensive.
The main issues relating to the static blade cleaning are turbine downtime and usage of expensive equipment. The site wind conditions are also important while cleaning the turbine blades using traditional methods as the standard cleaning process is recommended only when the site wind speeds are lesser than 10 m/s. This is due to safety issues at height as the technician needs to climb up with the help of ropes next to the blades. The amount of water utilized for cleaning in accordance with traditional cleaning methods is also considerably high.
There is a need of a kit and a process for cleaning wind turbine blades with water mist that is projected from a predefined distance and predefined height relative to the turbine and the tower. A process for cleaning wind turbines is needed that can be executed while the wind turbine is in its standard mode of operation.
SUMMARY OF THE INVENTION
The present invention discloses a kit for cleaning a rotating wind turbine that comprises a carriage, a plurality of guns for misting water on the rotating turbine blades such that the axis of each of the guns is normal to a plane of the wind turbine rotor. The guns positioned at predefined heights relative to height of a tower of the wind turbine, the guns receive compressed water from the first tank. The first imaging device and a second imaging device monitor a pattern of misting fluid on the rotating turbine blades. A plurality of sensors monitors direction of the wind and maintain the position of the turbine rotor in a predefined direction. A removable carriage is positioned over a predefined height relative to the ground. The carriage includes the plurality of guns, a compressor, a motor and the first tank. The first tank is replaceable by a second tank that is approximately identical to the first tank. The first imaging device is positioned on the back of the turbine blade at a predefined position. The second imaging device is positioned on the ground in close proximity with the bottom end of the tower.
A process for cleaning a rotating wind turbine using a kit for cleaning the rotating wind turbine comprises steps of ensuring if the turbine is running in a standard operation mode, monitoring speed of the wind by a plurality sensors to check if the wind speed at wind turbine location is less than 10 m/s, predicting the wind speed for a predefined amount of time, positioning the crane on the ground at a predefined safe distance relative to the tower, positioning and locking the carriage at a predefined altitude and for a predefined amount of time, spraying the mist from one or more guns on the rotating turbine blade for a predefined amount of time, and replacing a first tank by an approximately identical second tank which is already full of water. The altitude of the carriage is fixed according to the relation between the height ‘H’ of the tower, and the rotor diameter ‘D’ of the present invention. The future speed is predicted on the basis of the historical data acquired by the sensors over time. Monitoring wind turbine speed includes checking that the turbine is not stagnant. The safe distance is (D/2+10m) in the centre line from the nacelle for ensuring the safety of technicians on the crane and turbine blades, in case there is a sudden shift of wind direction. The altitude of the carriage is fixed according to the relation between the height ‘H’ of the tower, and the rotor diameter ‘D’ of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
For a complete understanding of the present invention, reference should now be made to the following detailed description thereof taken in conjunction with the accompanying drawings wherein:
FIG. 1 is a kit for cleaning turbine blades in accordance with the present invention;
FIG. 2 shows positions of misting guns of the kit of FIG. 1 relative to the wind turbine in accordance with the present invention; and
FIG. 3a-c shows the rotating wind turbine blades being cleaned by using the misting kit of FIG. 1 in accordance with the present invention.
Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure.
BRIEF DESCRIPTION OF INVENTION
Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to particular structure of the invention selected for illustration in the drawings, and are not intended to define or limit the scope of the invention.
Referring to FIG 1, a kit 100 for cleaning a rotating wind turbine (Not shown) in accordance with a preferred embodiment of the present invention includes a plurality of misting guns 102, a first tank 104, a second tank 106, a first imaging device 108, a second imaging device 110, a plurality of sensors 112, a compressor 114, a motor 116 and a carriage or a basket 118. The carriage 118 includes the guns 102, compressor 114, motor 116 and the first tank 104. The carriage 118 is securely coupled with a boom (Not shown) of a crane.
The carriage 118 is removable and coupled to a hook of the crane that is in turn connected to boom of the crane. The first imaging device 108 is preferably positioned on the back of the turbine blade at a predefined position. The second imaging device 110 is preferably positioned in close proximity with the bottom end of a tower (Not shown) of the wind turbine.
The first and the second imaging devices 108, 110 advantageously monitor the misting pattern of the water mist falling on turbine blades and send respective signals to the control station. The misting guns 102 are positioned such that an axis of the gun is normal to the plane of the wind turbine rotor (Not shown). The sensors 112 in the wind turbine monitor the wind direction. For example, the sensor 112 in this preferred embodiment is an anemometer that senses the ambient wind speed. Signal from the sensor 112 continuously keep the turbine rotor facing the incoming wind. As a result the upwind carries the mist projected from the guns 102 by itself towards the rotor.
Now referring to FIG.2, the distance of the gun 102 from a wind turbine 200 is approximately equal to ‘D’ where ‘D’ is diameter of the rotor of the turbine. The guns 102 are positioned at various predefined heights relative to a bottom plane on which the tower 202 of the wind turbine 200 is normally positioned. In this embodiment, the guns 102 are positioned at various heights relative to the bottom plane, for example, H+D, H + (D/2), H, and H - (D/2) where H is height of the tower. Mist is created using the guns 102 using the compressor 114. The high pressure water come out from the house reel which is connected to the water pump run by an engine. Small water droplets are thrown from a predefined distance through the high pressure water spray, which mimics a rain like effect. In this embodiment, the high pressure water pumps throws the water spray at pressure of about 140 bars. The prime mover here consists of a petrol engine hence there is no requirement of electrical supply from the ground below.
The guns 102 preferably operate at, for example, 140 bar and flow rate of 52 liters per minute from a predefined distance ‘D/2+10m’ as illustrated. It is to be noted that the ambient wind speed to clean the blades 204 of the wind turbine 200 in accordance with the present invention is in a range of 4m/s to 25 m/s which are the production start and production stop wind speeds respectively for the wind turbine 200. It is to be noted that the arrows indicated by letter ‘A’ indicate the direction of the wind and the arrows indicated by letter ‘B’ indicate the direction of rotation of the blades.
Now referring to FIG. 3a-c, a preferred process of cleaning turbine blades 204 in accordance with the present invention is described. A first step of cleaning the blades 204 includes ensuring if the turbine 200 is running in a standard operation mode. This step advantageously includes checking that the turbine 200 is not stagnant. In a next step, the wind speed is monitored by the sensors 112. In this step, the sensors 112 check if the wind speed at wind turbine location is less than 10 m/s. In a next step, the wind speed for next few hours is predicted.
The future speed is predicted on the basis of the historical data acquired by the sensors over time. In accordance with the present invention, the predicted wind speed should be less than 10 m/s for the duration during which the cleaning operation is done. The speed check and the speed prediction advantageously ensure the overall safety of the turbine 200 and technicians.
In a next step, the crane is positioned on the ground at a predefined safe distance relative to the tower 202. The safe distance is the distance of misting kit from the tower base. In this one embodiment, the safe distance is (D/2+10m) in the centre line from the nacelle. The distance ensures the safety of technicians on the crane and turbine blades 204, in case there is a sudden shift of wind direction. It is to be noted that the safe distance is a secondary safety measure, as the first safety measure, the controller (Not shown)of the wind turbine 200 disallows the rotor to change its direction so abruptly, for example, sudden yawing.
In the next step, carriage 118 is positioned at a predefined altitude and the positioned is locked for a predefined amount of time. The altitude of the carriage 118 is fixed according to the relation between the height ‘H’ of the tower 202, and the rotor diameter ‘D’ of the present invention. The position of the carriage 118 advantageously allows any gun 102 to position and spray the mist from the altitude of the carriage 118.
In this step, the carriage 118 and thereby the guns 102 are movable from the height (H-D) to H in a plane normal to the ground where H is the tower height of the wind turbine and D is the rotor dia. The positions of the guns 102 are movable by the moving the carriage 118. The guns 102 are preferably fixed on predefined platforms such that the guns are movable by a respective joy stick (Not shown). In another embodiment, the guns 102 are held by technicians with their hands.
In a next step the mist is sprayed from the gun 102 on the turbine blade 204. For example, if the flow rate of mist from the gun 102 is 52 liters/min then the first tank 104 having volume of approximately 1000 liters is usable for about 18 minutes. The carriage 118 is brought down on the ground in a next step. In the next step, the first water tank 104 is replaced by the second water tank 106 which is already full of water. The first operational cycle is completed.
In another operational cycle, the crane lifts the carriage 118 up to the height H. Once the carriage 118 reaches the desired height, the position of the carriage 118 is locked. The technician holds the mist gun 102 and focuses the gun 102 on the area below the center of the rotor as shown in Figure 1 and Figure 2. Mist spray is then carried out for another 18 minutes till the 1000 liter water in the first tank 104 gets fully utilized. Once the operation is completed, the carriage 118 is brought down to the ground level, wherein the first tank 104 is replaced with the fully filled second tank 106 .
The preferred process of cleaning the turbine blades 204 includes creating mist with the help of water and air. The mist is preferably projected in front end portion of a wind turbine rotor while the wind turbine is rotating between 10-30 rpm. The mist is spread in the direction of flow of the wind such that the mist by virtue of the wind direction tends to fall on the rotor. The mist gets carried with the upwind and reaches the rotor.
The mist includes water particles that hit the rotating blades having high local rotational speeds gives a brushing effect and hence cleaning the blade 204. The water particle falling on the blades with a predefined force preferably dislodge the debris on the blades 204. The continual falling of the droplets on the dislodged debris washes away with the water falling from the blades 204.
It is to be noted that the relative local speed of the wind turbine blades 204 is advantageously utilized that is preferably in the range of (100 to 250km/hr). The high speed of blades in combination with the mist defines the brushing effect that cleans grime and dirt from the blades. The cleaning operation of the turbine blades in accordance with the present invention is preferably done between cut in and cut out speeds for the wind turbine in a range of approximately 4 m/s to 25 m/s
In one embodiment of the present invention the water used for cleaning blades 204 may include cleaning additives like detergents which can further help in cleaning the blades. The water can also have the additives which discourages the insects sticking to the blade surface. The water can have the additives which can avoid the formation of the algae on the blade surface. The water can have additives which can help in avoiding dust accumulation on the blade surface. The water used for the mist-spray can be hot or cold as per the need. Since mist is used for cleaning, the usage of water is minimal hence the present is very advantageous at the wind farms where the water availability is scarce.