The present invention relates to an improved hydraulic system for actuating the electro-hydraulic actuators of various valves in high pressure turbine bypass system of a thermal power plant, or more specifically a method for detecting any fluid leakage or blockage visually by providing an additional component to the system.
BACKGROUND OF THE INVENTION:
In a thermal power plant steam is generated in the tubes of boiler by absorbing the heat generated by burning of coal. This steam when reached to superheated steam phase is allowed to impinge on the blades of high pressure turbine which in turn rotates and makes the rotor connected to it to rotate resulting in power generation.
The pipeline which allows steam to high pressure turbine is called Main steam line and the outlet of the high pressure turbine is called Cold reheat line. The steam from the main steam line is expanded in the high pressure turbine causing the reduction in pressure and temperature of the steam and is sent back to boiler through cold reheat line.
During start-up of the power plant only wet steam (i.e. Steam which contains water particles) will be available in the boiler which cannot be impinged on the turbine as wet steam may cause erosion of the turbine blades. Also, when the turbine trips of its operation due to any technical issues, the steam should not be allowed to turbine and boiler should be kept in running condition. In both the above cases, the steam should be diverted from impinging on the high pressure turbine.

In order to divert the steam from impinging on the high pressure turbine and safely route it to cold reheat line, a control valve called High pressure turbine bypass valve is used in the power plant. This valve is operated based on the steam pressure in the main steam line and temperature feedback of the cold reheat line.
Oil availability in the hydraulic lines with required pressure should be ensured to keep the high pressure turbine bypass system available for operation.
To keep the desired oil pressure at the pressure line of oil system, all the pressures and pump running status are continuously monitored from the control room.
If there is any oil leakage, the pump in the hydraulic power unit keeps on running continuously (which should not happen in normal condition) to maintain the required oil pressure in the hydraulic lines.
in all the conventional hydraulic systems of art, the pump in the hydraulic power unit keeps on running to maintain the required oil pressure, due to which power has been wasted.
Initially, for finding out accurately the root cause of leakage, all the hydraulic pipelines in the hydraulic system are checked thoroughly for oil flow which results in loss of time.
Further, as per the conventional hydraulic system, oil will be always available in the hydraulic lines, hence, there is lot of oil loss when the hydraulic oil lines are opened. However, man power is also required to open, inspect and close the hydraulic lines repeatedly.

Hence, there is always a long felt need to provide an innovative yet simple and quick method to identify the oil leakage or blockage of any in the hydraulic lines.
The present invention meets the long felt need by providing an improved hydraulic system which can check any oil leakage or blockage only by visual inspection and hence this saves loss of fluid, loss of energy and time substantially.
OBJECTS OF THE INVENTION:
It is the principle object of the present invention to provide an improved hydraulic system which comprises a transparent tube for detecting fluid leakage through components of hydraulic system and thereby reducing the time required for identification of the source of leakage of fluid in the hydraulic system.
Another object of the present invention to provide an improved hydraulic system which checks the fluid wastage as the tube need not be opened for detection of source of fluid leakage.
Yet another object of the present invention to provide an improved hydraulic system which reduces the human resources required for detection of source of fluid leakage.
Further object of the present invention to provide an improved hydraulic system which will reduce the power wastage by the pump to develop the required fluid pressure in the presence of leaking hydraulic components.

BRIEF DESCRIPTION of THE ACCOmPANying DRAWINGS:
It is to be noted, however, that the appended drawing illustrated only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments.
The detailed description is described with reference to the accompanying figure. In the figure, the left-most digit (s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figure to reference line features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figure.
Figure-1 illustrates the schematic diagram of the proposed hydraulic system of high pressure turbine bypass system, in accordance with an embodiment of the present subject matter;
The figure depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and method illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION OF THE PREFFERRED EMBODIMENTS:
The subject matter of the present invention relates to an improved hydraulic system for actuating the electro hydraulic actuators of various valves in a high pressure turbine bypass system which comprises minute spaces within their construction which will help to detect the leakage or

blockage of fluid by visual inspection and eventually enhance the overall performance of the hydraulic system.
According to figure-1, the main body of the thermal power plant has been illustrated, wherein two main steam lines (I) has provided in the upstream of the high pressure turbine to transfer steam from boiler to turbine. Two cold reheat lines have also provided (II) in the down stream of the high pressure turbine to transfer steam from turbine to boiler.
For these type of transfer of steam, some valves have been provided such as two high pressure turbine bypass valves (1) to bypass the high pressure turbine, two spray water control valves (3) to provide water to the bypass valves (1) and atleast one spray water isolation valve (2) between the boiler feed pump and spray water control valves (3).
All of these valves according to Figure-1 are operated by different hydraulic actuators (4, 5, 6).
The position of the above three types of valves are measured and the feedback is provided to control room by position feedback transmitter
(7,16) and limit switches (26).
The hydraulic actuators are double acting piston cylinders operated by the fluid flow on the two sides of the piston in the cylinder. The fluid for actuators is supplied by the hydraulic power unit (17)
In one embodiment of the present subject matter, the hydraulic power unit has been provided which comprises the hydraulic power unit (17) consists of tank which acts as an fluid reservoir, pumps & motors for pumping fluid, accumulators for storing fluid at high pressure, pressure

reducing valve for pumping fluid in a predefined outlet pressure, pressure relief valves which acts as safety devices for the components of the hydraulic power unit, cooling fan for cooling the fluid based on requirement, pressure transmitters for measuring pressure at various points in hydraulic power unit and provide feedback to controller, level transmitters for measuring fluid level in the tank and to provide the feedback to controller and temperature transmitters for measuring the temperature of the fluid and provide feedback to the controller.
In another embodiment of the subject matter the hydraulic fluid from the hydraulic power unit (17) is pumped to the actuators through the pressure lines (IV) of the hydraulic system which consists of non-return valves (23), isolating ball valves (22), high pressure filters (13 &14), high pressure hoses (21) and direction control valves (10, 11 8s 12). The fluid from the hydraulic actuators is drained to tank of hydraulic power unit through tank lines (VI 8B VII) of the hydraulic systems starting from the direction control valves which consists of throttle devices (24), isolating ball valves (22), transparent tube (29) and non-return valves (23).
During turbine trip condition, the high pressure turbine bypass valves needs to be opened very fast i.e. within 2-3 seconds. For enabling the fast opening of the high pressure turbine bypass valve, a fast opening device (18) is mounted on the actuators (04) of high pressure turbine bypass valve. Fluid from hydraulic power unit (17) is pumped through pressure line (V) which consists of high pressure filters (20) and accumulators with their manifolds (19). These accumulator manifolds contain safety valves and drain valves for ensuring the safety and maintenance requirements of the accumulator. When a fast open command is given to the fast opening device (18), fluid from the accumulators (19) enters into the actuators (04) and the fluid from the actuators will be flowing to the

tank of the hydraulic power unit (17) through return line (VIII & IX) which consists of isolation ball valve (27), transparent tube (29) and non¬return valve (28).
In one implementation of the present subject matter the high pressure turbine bypass valves, spray water isolation valves and the spray water control valves (01, 02 8B 03) are operated only when they are required and in all other conditions they will be kept in fully closed condition. However to ensure availability of the above mentioned valves, the motors of the hydraulic power unit (17) are operated such that required fluid pressure is always available in all the pressure lines of the hydraulic system for the actuators (04, 05 8s 06) to operate at all the times.
All the pressure lines and return lines of the hydraulic system are stainless steel tubes. All the above mentioned direction control valves (10, 11 , 12 and 19) and manifolds contains minute spaces within their construction. If there is any obstruction caused due to fluid contamination or due to any other foreign particles, this will lead to leakage/blockage of fluid in these components and will result in malfunctioning of the system like, continuous running of pump as there will not be pressure rise because of continuous leakage of fluid. Hence by arranging a considerable length of transparent tube (29) at various locations of the hydraulic system as indicated
in the Figure-1, any flow/no-flow in the return lines (VI,VII,VIII and IX) due to leakage/blockage of the hydraulic components can be found out just by visual inspection and hence avoiding loss of energy, loss of fluid, loss of time, loss of resources and loss of money due to unavailability of the system. Hence if a doubt of fluid leak or fluid block in the hydraulic system is reported (or) non-development of required fluid pressure in

pump running condition is reported (or) rupture of elastomers in the hydraulic components is reported, the source of this mal performance can be easily identified by visual inspection and the component which is not performing as per requirement should be corrected to reduce/remove the leakage/ blockage.
Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system or device of the present invention will be apparent to those skilled in art and thus it is intended by the appended claims to cover all such modification and adaptations which fall within the scope of the present invention.

WE CLAIM:
1. An improved hydraulic system in a thermal power plant comprises
main steam lines for transferring steam from boiler to turbine and vice
versa alongwith different type of valves such as herein described,
hydraulic actuators, pressure lines, pumps, motors for pumping fluid,
accumulators for storing fluid at high pressure, direction control valves
(10, 11 and 12) manifold (19) which further comprises minute spaces,
transparent tubes of on optimum length at various locations (29) for detecting the leakage or blockage of the hydraulic system through visual inspection.
2. The improved hydraulic system as claimed in claim 1, wherein said
valves are two high pressure turbine bypass valves (1) to bypass the high
pressure turbine, two spray water control valves (3) to provide water to
the bypass valves and atleast one spray water isolation valves (2) for
isolation of water from boiler feed pump.
3. The improved hydraulic system as claimed in claim 1, wherein said valves are operated by hydraulic actuators (4, 5 and 6) and the position of said valves are measured and the data has been transferred to control room by position feedback transmitters.
4. The improved hydraulic system as claimed in claim 1, wherein said hydraulic actuators are double acting piston cylinders which are operated by the flow of fluid on both sides of the piston.

5. The improved hydraulic system as claimed in claim 1, wherein said pressure lines further comprises a non-return valves (23), isolating ball valves (22) and high pressure filters (13 and 14), high pressure hoses (27) and direction control valves (10, 11 and 12) .
6. The improved hydraulic system as claimed in claim 1, wherein the said tubes are transparent which helps to check the oil flow visually.
7. The method to check the leakage or blockage with the hydraulic system as claimed in claim 1, wherein said transparent tube (29) of optimum length has been placed at various location, so that any type disturbance in flow line can be detected by visual inspection.
Dated this 31st day of March> 2£g^u^J-€-e
(I. BANERJEE)
L.S.DAVAR & CO. APPLICANT'S AGENT