EP0471321B1

EP0471321B1 - Method and apparatus for creating an increased hydrodynamic head of fluid jets

Info

Publication number: EP0471321B1
Application number: EP91113497A
Authority: EP
Inventors: Efim Fuks; Vadim Fuks; Vladimir Lunev; Sergey Lunev
Original assignee: APRIL DYNAMICS INDUSTRIES 1990 Ltd
Current assignee: APRIL DYNAMICS INDUSTRIES 1990 LTD.
Priority date: 1990-08-12
Filing date: 1991-08-12
Publication date: 1995-11-22
Anticipated expiration: 2011-08-12
Also published as: IL95348A0; EP0471321A1; DE69114783T2; DE69114783D1

Description

This patent application relates to jet technique and is intended to heat up as well as supercharge liquid in various applications.
It has been known that methods of generation of hydrodynamic head of fluid jet comprise mixing a liquid with a gas (a steam) and subsequent condensation in full or in part of the gaseous phase.
These methods have extensive applications in various industries and are being realized in injector devices.
A shortcoming of these methods is that according to theory, a liquid pressure at the injector exit cannot exceed the half-sum of both liquid and gas pressures at the injector inlet.
There is a known method for generating a hydrodynamic head of fluid jet, a method which comprises setting up a two-phase steam-liquid mixture, providing flow regime of this mixture with a velocity which is in excess of the sonic speed for this mixture and the gas phase is condensed or dissolved in shock wave - abrupt pressure rise - condensation zone (see e.g. Deich, M.E. and Philippov, G.A., "Gasodynamics of 2-phase mediums", Moscow, 1968, pp. 267-274). This method makes it possible to increase the fluid head inside the post-shock zone by about one and a half times in relation to working medium pressure.
One example of such a system is shown in EP 0 150 171 which describes a supersonic injector utilizing gas absorption in a supersonic liquid-gas mixture, resulting in a shock-wave region.
The degree of this pressure increase is insufficient.
It is the aim of this patent application to provide a method for a substantial increase of hydrodynamic head of liquid jet inside the post-shock zone.
This aim can be obtained by side-draining at least a portion of the liquid from the shock-wave zone.
Let us consider an example of performing this method in the case where hydrous steam is used as a gaseous phase. There are two ways to create a flow of a water-steam mixture:

a) Mixing water and steam streams.
b) To cause liquid boiling by flowing the liquid at high speed.

This is a metastable structure and it leads to a transition from supersonic flow of the steam-liquid stream to subsonic flow of a liquid stream.
This transition is accomplished in the shock wave - abrupt pressure rise - condensation zone. In the shock wave zone occurs quick and complete condensation of the steam phase of the flow. As a whole, steam energy cannot be immediately converted to heat, so a part of this energy is converted to mechanical work.
It causes an increase of hydrodynamic head of fluid jet in the post shock zone.
Hydrodynamic effects taking place at side draining liquid in full or in part from the shock wave - abrupt pressure rise - condensation zone lead to an increase of hydrodynamic head of fluid jet at the post shock zone.
In case of full draining of the liquid, a high hydrostatic pressure is produced in the post shock zone.
Using the described method in a multi-stage device (doing the set of the above mentioned operations repeatedly), it is possible to achieve a very high absolute pressure of the fluid jet.
Mixing draining part of the flow in full or in part with the liquid incoming for generation of a two-phase steam-liquid stream results in saving both liquid and steam energy.
Below is a table of test results of an industrial specimen of a pump-heater device which realizes the described method.

P stream inlet (bar) 1 2 3

P water outlet (bar) with partial draining 6 9 16

P water outlet (bar) with full draining 9 14 20
Drawing 1 is a simplified description of a device which utilizes the method mentioned in this patent application. It is one of various options for implementing the process mentioned above.
The shown device comprises a nozzle 1 with an inlet 2 for introducing steam and coaxial to the nozzle a body 3 with an inlet 4 for introducing liquid, and a mixing chamber 5. The mixing chamber 5 comprises an outlet 6 for the liquid and an auxiliary exit (side draining) 7.

Claims

A method of increasing the hydrodynamic head of a fluid jet in an injector comprising the steps of:
a) forming a two-phase gas-liquid or steam-liquid mixture travelling at a velocity greater than the speed of sound for the mixture;

b) generating a shock-wave in said mixture by causing condensation or dissolving of said steam or gas in said liquid, whereby the velocity of said mixture is no longer supersonic, thereby causing a shock-wave at a shock-wave zone, whereat the pressure of said flow increases abruptly,
characterized in side draining at least a portion of the liquid from the shock-wave zone, whereby the pressure rise caused by said shock wave is increased.
A method according to claim 1 wherein the step a) comprises the step of supplying a liquid and a gas, whereby the two-phase mixture is a gas-liquid mixture.
A method according to claim 1 wherein the step a) comprises the step of supplying a liquid and a steam whereby the two-phase mixture is a steam-liquid mixture.
A method according to claim 1 wherein the step a) comprises the step of supplying a liquid and increasing the speed of the liquid such that the liquid boils.
A method according to claim 2 or claim 3 wherein the two-phase supersonic mixture is formed by mixing liquid with a supersonic stream of gas or steam.
A method according to any of claims 2 to 5 wherein the supplied liquid is comprised of fresh liquid and drained liquid.
A method according to claim 1 wherein the two-phase supersonic mixture is formed by mixing liquid with a supersonic stream of gas or steam.
A method of according to any of claims 2 to 6 characterized by repeating the method steps of any of the preceding claims wherein the high-pressure liquid is supplied as part of the step of supplying.
Injector apparatus for increasing the head of a fluid jet comprising:
a gas or steam inlet (2);
a liquid inlet (4);
means (1,3) for forming a two-phase gas-liquid or steam-liquid mixture travelling at a velocity greater than the speed of sound for the mixture;
a flow conduit (5), which receives the two-phase supersonic mixture from the means for forming, within which conduit a shock wave is generated in said mixture by causing condensation or dissolving of said steam or gas in said liquid, whereby the velocity of said mixture is no longer supersonic, thereby causing a shock-wave whereat the pressure of said flow increases abruptly,
characterized by a side drain (7) at the zone of the shock-wave which drains at least a portion of the liquid from the zone of said shock-wave, whereby the pressure rise caused by said shock wave is increased.
Apparatus according to claim 9 wherein the means for forming comprises means for forming a two phase gas-liquid mixture travelling at a velocity greater than the speed of sound for the mixture.
Apparatus according to claim 9 wherein the means for forming comprises means for forming a two phase steam-liquid mixture travelling at a velocity greater than the speed of sound for the mixture.
Apparatus according to any of claims 9 to 11 and comprising means (3, 4) for mixing liquid with a supersonic stream of gas or steam thereby forming said two phase supersonic mixture.