Method and arrangement for maintaining fluid flow pressure in a system at a preset, almost constant level
AssigneeSolar Water Solutions Oy
InventorHeikki Antero POHJOLA
Life of this patent
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Abstract
A method and arrangement for maintaining fluid flow pressure in a system at a preset, almost constant level. One application is an impulse turbine's nozzle valve, which automatically maintains the system pressure essentially constant so that it does not depend on occasional variation of the pumped inflow, resulting that also the jet from the nozzle remains constant and its kinetic energy optimal. The nozzles independently maintain system pressure when the inflow varies.
Claims10
A method for maintaining fluid flow pressure in a system at a preset, almost constant level, not depending on periodical variation of the mass flow pumped into it, which system comprises at least one pressure accumulator and a nozzle valve, which has a valve body and axially inside it a conical needle for opening and closing the mouth of its outflow channel, and the needle shaft is guided by a slide element mounted inside the valve body and inflow into the valve body can pass to the other side of the slide element through one or several channels and the needle is moved axially to directions for opening and closing the valve by means of the forces which are affecting on it and thus it adjusts the cross-sectional area of the outflow channel mouth, the method comprising:
- exerting a force on the needle shaft by the flow pressure (p1) and a spring together, the direction of this combined net force is upward in all situations and the combined net force holds the needle shaft end constantly pressed against the pressure accumulator's valve disc tending to open it, but is always smaller than the opposite force which in the accumulator pre-pressurized gas pressure (p0) exerts on the valve disc,
- wherein the mentioned combined net force in combination with the force, which the flow pressure (p1) is exerting on the valve disc form the first force which tends to open the outflow channel against the second and opposite force, which the accumulator's gas pressure is exerting on the valve disc,
- whereby, when the first force exceeds the second force, begin both the valve disk and the needle which is pressed against it, together, to rise, with the result that pressure (p2) in the accumulator increases accordingly, and choosing the diameter of the outflow channel mouth, cone angle of the needle and volume of the pressure accumulator so that the gas volume change in the accumulator caused by the needle rise and the resulting increase in the accumulator's pressure is small also with maximal flow, with the result that the relationship between the mentioned forces automatically adjusts the opening grade of the valve so that the fluid flow pressure (p1) remains close to the initial pressure (p0) pre-pressurized in the accumulator, while the fluid flow through the outflow channel remains all the time continuous.
An arrangement for maintaining fluid flow pressure in a system at a preset, almost constant level, not depending on periodical variation of the mass flow pumped into it, which system comprises:
- at least one pressure accumulator and a nozzle valve, which has a valve body and axially inside it a conical needle for opening and closing the mouth of its outflow channel, and the shaft of the needle is guided by a slide element mounted inside the valve body and the inflow into the valve body can pass to the other side of the slide element through one or several channels, and the needle is arranged to be moveable upwards to the opening direction of the valve and downwards by means of the forces affecting the needle, in order to adjust the cross-sectional area of the outflow channel mouth, wherein to the upper end of the valve body, opposite the outflow channel, is joined a diaphragm or bladder accumulator having a pre-pressurized initial gas pressure (p0), and between the valve body and the accumulator is formed a channel through which the needle shaft end is arranged to be essentially pressured against the valve disc of the accumulator and to move together with it, the initial pressure (p0) causing a downward force tending to close the valve, that when the valve disc is at its lowest position and supported by the accumulator body, the conical head of the needle essentially closes the mouth of the outflow channel, and into the system pumped mass flow is adapted to cause on the valve disc and needle forces, which tend to open the valve, and a pre-tensioned spring is arranged to cause on the needle a spring force (Fs) which tries to lift the needle and this spring force combined with the mass flow forces tends to rise the valve disc and the needle against the force, which the initial pressure (p0) in the accumulator causes on the valve disc, in order to open the outflow channel and at the same time increase pressure in the accumulator to the level (p2) which corresponds the rise of the needle, and that diameter of the outflow channel mouth, cone angle of the needle and gas volume in the accumulator are so chosen that the gas volume change in the accumulator caused by the needle rise and the resulting pressure increase in the accumulator is small also with maximal flow volume, resulting that the pressure accumulator adjusts the cross-sectional area of the outflow cannel mouth so that the flow pressure (p1) of the fluid which will flow out and by this means pressure in the whole system remains close to the pre-pressurized initial pressure (p0) in the accumulator.
Dependencies are inferred from the claim text.