Fluid handling – Systems – Flow path with serial valves and/or closures
Patent
1993-10-21
1995-08-08
Chambers, A. Michael
Fluid handling
Systems
Flow path with serial valves and/or closures
251121, 251282, F16K 4700
Patent
active
054390303
DESCRIPTION:
BRIEF SUMMARY
The objective of this application is a pressure reducing valve intended for high pressure drop services which offers outstanding innovations and important advantages over existing control valves used in similar services.
It is well known that when the pressure drop across a control valve is high, there will be noise, vibrations and fast wearing of the parts of the valve which throttle or control the flow, the plug, the seat ring and the cage or cylinder.
Also there is a friction between the moving parts, due to the difference in pressure in the left-right sides of the valve (which is asymmetric) and pushes in the horizontal direction the plug against the cylinder.
Also, if the plug is not balanced in the vertical direction, the force required by the plug to be moved will be larger, and the movement will not be smooth unless oversized actuators are used.
Referring to the state of the art, it has to be said that there are several types of control valves, which either do not solve the problem or they solve the problem in a complicated and costly way, as we are going to see.
A solution is to have 2 or more control valves one after the other, each of them taking a part of the total pressure drop, which is an expensive solution.
There are also control valves having inside complex throtting cages, made of several disc stacks or cylinders, one above or inside the other, which also divide the total pressure drop across the valve in two or more pressure drops, but increasing enormously the complexity of the design and the cost, and also reducing the flow capacity of the valve.
Also, the problem of the side forces, which give friction and wearing of plug and cylinder, has not been solved yet. In existing designs large parts of the plug are exposed to differential pressure around its cylindric surface, this giving side forces, proportional to the surface and the pressure differences. It gives vibration sometimes, friction and wearing in all cases. This is a particularly serious problem in large size valves.
The new control valve which is the object of this application, designed for high pressure drop, reduces the total pressure drop in several stages, gradually, and eliminates in a simple way noise, vibration and wearing problems.
The new design of the internal parts of the valve makes the fluid to change direction several times and creates also internal chambers which are intermediate steps or stages of the pressure.
This design solves for the first time the problem of the side forces, by means of the balancing ring chambers. This chambers are ring spaces around the plug which balance the side forces acting in a horizontal direction. In this way the plug is not pushed against the guiding cylinder and friction and wearing are reduced.
Also the plug has been designed with a middle chamber sized to allow the pass of flow and to compensate the forces in the vertical direction. So the plug is balanced at all positions along its stroke and the forces required to move it are very reduced.
To give a detailed description of the invention, reference will be made to the enclosed figure, which, as an example and without being limited to, has been represented as a preferred but not the only way of execution.
In the drawings:
FIG. 1 represents a sectional view of the valve object of the invention.
FIG. 2 represents a detail of FIG. 1
In FIG. 1 are shown the main parts of the valve: decreasing in size.
The design is based on the division of the total pressure drop on several minor pressure drops. To achieve this it creates inner chambers or intermediate stages, in the way of the flow, combining the different diameters of the plug with the correlated diameters of the seat ring 2, 3, 4 or more steps as required by the total pressure drop.
In FIG. 2 a 4 stages pressure drop design is represented, having three chambers or intermediate stages:
With this layout the flow comes from the high pressure side from under the seat ring through the holes of the seat ring cylinder (1-4) which is the first restriction, to the chamber (4) which is t
REFERENCES:
patent: 974337 (1910-11-01), Aslakson
patent: 2931615 (1960-04-01), Campbell
patent: 3799199 (1974-03-01), Rumpff
Badain S.L.
Brosemer Jeffery J.
Chambers A. Michael
Michaelson Peter L.
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