WO1980000382A1

WO1980000382A1 - Method and device for controlling a liquid level

Info

Publication number: WO1980000382A1
Application number: PCT/FR1979/000070
Authority: WO
Inventors: Carrou J Le
Original assignee: Carrou J Le
Priority date: 1978-07-27
Filing date: 1979-07-27
Publication date: 1980-03-06
Also published as: GB2043253B; GB2043253A; FR2432165B1; FR2432165A1

Abstract

Process and device for controlling the level of a liquid contained in a housing (1). A housing contains a condensor (8) in which a gaseous fluid is introduced. When the condensor dips into the liquid, the fluid is condensed and it is the pressure of the contained fluid which actuate the control member for controlling the liquid level.

Description

Method and devices for controlling the level of a liquid.

The present invention relates to a method and devices for monitoring the level of a liquid contained in an enclosure.

It is common in industry to have to control the level of a liquid contained in an enclosure so as to avoid the presence of an excess of liquid in the enclosure, an excess liable in particular to cause an overflow, or so to be maintained at a certain height, the interface being between two liquids of different densities.

This is particularly the case for sumps intended to collect rainwater in petroleum product storage yards, for example, or for ship's holds.

This is also the case for enclosures supplied permanently or not, with a liquid whose flow is ensured by a valve.

Another conceivable case is that of regulating the level of an interface between two liquids of different densities and substantially immiscible (for example aqueous phase - organic phase, such as product

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»IPO more or less viscous)) •

The control of the level of a liquid in such cases is the subject of more or less complicated devices. We can cite for example that comprising a float mounted on a joint and actuating a discharge system when the liquid, and therefore the float, reaches a determined level in the enclosure. This system is not very reliable, because the float is a fragile element, susceptible to puncture and the joint happens to block.

The Applicant has developed a particularly simple and reliable device for controlling the level of a liquid contained in an enclosure.

The object of the present invention is therefore to control the level of a liquid contained in an enclosure.

The present invention therefore relates to a method for controlling the level of a liquid contained in an enclosure, said method consisting in continuously supplying a condenser placed in said enclosure, with a fluid brought to the gaseous state under pressure p and being at a temperature tl, higher than the temperature t2 of said liquid, said fluid being capable of condensing at said pressure p and at said temperature t2, said method comprising the following steps:

a) the condensation of said fluid in said condenser when the level of the liquid in the enclosure is such that said condenser plunges into the liquid and that said fluid is therefore at temperature t2,

b) the evacuation of said condensed fluid, out of the condenser, said evacuation causing under the effect of the pressure of the condensed fluid, the withdrawal of the liquid contained in the enclosure outside said enclosure, and / or stopping the supply of liquid to the enclosure,

c) stopping the evacuation of said fluid from said condenser, causing the withdrawal of said liquid to be withdrawn from the enclosure, and / or resumption of supply to the enclosure, when the level of the liquid contained in the enclosure is such that the condenser is located outside the liquid and therefore at a temperature above t2 such that said gaseous fluid no longer condenses therein,

d) repeating steps a) and b) as soon as the condenser plunges back into the liquid.

The invention also relates to devices for implementing the method according to the invention.

The method according to the invention therefore consists in condensing in a condenser, when the latter is immersed in the liquid whose level is to be controlled, a fluid brought to the gaseous state, and being at a temperature tl, said fluid supplying continuously said condenser. It is of course necessary for this condensation to be possible, that is to say that at the temperature t2 of the liquid, and therefore of the condenser, the gaseous fluid being at a supply pressure p, is capable of condensing. The shape of the condenser can be very variable; it may for example be a simple tube or a coil.

When the fluid is condensed in the condenser, said condensed fluid is evacuated automatically, out of said condenser. This evacuation is carried out using an organ, for example a thermostatic trap, which lets the body pass only when it is in the condensed state. A thermostatic trap contains an element which, depending on whether it is in contact with the gaseous fluid. at temperature tl, or the condensed fluid at temperature t2, closes or opens the trap. This element can be, in particular, a bimetallic strip or a bellows element containing alcohol.

In the method according to the invention, it is the pressure of the condensed fluid which causes the liquid contained in the enclosure to be drawn off, and / or the supply of the enclosure with the liquid to be stopped.

This can be obtained in particular by triggering by the pressure of this fluid, using a servomotor, the starting of a pump capable of drawing the liquid out of the enclosure, and / or the control of a valve located on the enclosure supply line.

The pressure of the condensed fluid can also be exerted on an automatic diaphragm valve. This is placed in bypass of the supply of gaseous fluid. It opens when the pressure of the condensed fluid is exerted on it. The gaseous fluid is then led to an ejector, and by placing between the valve and the ejector a line immersed in the liquid, the latter is drawn off by entrainment by the gaseous fluid.

The liquid and the fluid used in the process according to the invention can be different or similar. In both cases, it can be water. The method and the devices according to the invention can have many applications: control and regulation of the level of liquids in tanks, sumps, ship holds, decanters, etc.

The four figures appended to this description illustrate, without limitation, the present invention. Referring to Figure 1, the enclosure in which we want to control the liquid level is constituted by a sump 1 containing water.

The device according to the invention consists of a line 2 for supplying water vapor optionally equipped with a valve 3. The vapor is at a temperature of approximately 230 ° C., and at a pressure of 6 , 5 bars absolute.

The valve 3 is connected by lines 4 and 5 to an automatic valve 6, and by lines 4 and 7 to a condenser 8. The condenser 8 is shown in the figure in the form of a coil, but it can have any other form, and in particular be constituted only by a part of the line 7. The condenser 8 is connected to a thermostatic trap 9. The latter is connected by line 10 to an automatic valve 6. Line 10 is equipped with a safety valve 11, a calibrated discharge orifice 12 and, optionally, a pressure gauge 13. The valve 6 is connected by line 14 to an ejector 16 whose outlet is constituted by line 17 A line 15 plunging into the water contained in the sump is connected to line 14.

The device works as follows:

1. The water level in the sump is low (line AA ⁸ ?

The automatic valve 6 is closed. The water vapor arrives through lines 2, 4, 7 (the valve 3 being open) in the condenser 8. This being above the level of the water contained in the sump, the water vapor heats up the condenser and does not condense there, or very little. The small amount of water capable of condensing therein is discharged by the trap 9 in line 10. This small amount of water is however not sufficient to establish a pressure on the membrane 18 of the valve 6, and is

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2. The water level in the sump is high (line BB

The automatic valve 6 being always closed, the water vapor arrives through lines 2, 4 and 7 (valve 3 open) in the condenser 8. The latter being below the level of the water contained in the sump, and therefore maintained at room temperature, the water vapor condenses there. The condensed water is discharged through the trap 9 in line 10.

The amount of condensed water is such that the calib orifice is insufficient to evacuate it, and the pressure exerted on the membrane 18 of the valve 6 causes the cell to open. The vapor then passes through line 14 to the ejector 16, and entrains the water contained in the sump. The water is discharged through line 17.

The water level drops in the sump when the condenser 8 returns above the level AA ', the water vapor no longer condenses there, and the valve 6 closes.

The cycle starts again when the water level rises in the sump.

The device according to the invention therefore makes it possible to control the level of water in the sump.

With reference to FIG. 2, which illustrates another device, in accordance with the present invention, the elements identical to those of FIG. 1 have been identified by the same numbers assigned to the index. different parts of FIG. 1. In this device, the trap 9 * is connected directly by line 20 to an automatic valve 21. In this automatic valve, in the part 22 of the valve located before the membrane 23, an orifice is formed. discharge calibrated 24.

O WI Through this orifice is likely to be evacuated the small amount of water capable of condensing in the condenser 8 * when the latter does not immerse in the sump water. This leak is interesting, because it makes it possible to maintain the presence of hot liquid in line 20, which was not the case with line 10 in FIG. 1. A phenomenon of frost in winter can thus be avoided.

In addition, the device shown in FIG. 2 is particularly compact, and the automatic valve 21 and the trap 9 ′ can be part of the same assembly represented by the lines 25.

The operation of this device is also similar in all respects to that of device 1.

FIG. 3 illustrates another possible use of the method according to the invention. In this figure, the same elements have been identified with the index ", the elements identical to those of FIG. 1. The enclosure 26 is here filled with two substantially immiscible liquid phases 27 and 28, hence the existence of the interface 29. These phases can for example consist of water on the one hand, and at least one organic liquid on the other hand. Petroleum products can for example constitute this organic phase. of heat at the level of the condensing member 8 "varies depending on whether it is bathed either by the aqueous phase, or by the organic phase. Thus, if the condenser 8 "is in the organic phase (as shown in the figure), a certain quantity of vapor is condensed, passes through the trap 9" and is evacuated by a calibrated orifice 12 "; there there is no pressure on the diaphragm of the servo motor 33 and the automatic purge valve 30 is closed. If, however, the level of the interface 29 rises, and the condenser 8 "is immersed in the aqueous phase, the the quantity of condensed vapor is greater, the pressure rises on the diaphragm of the actuator, and causes the purge valve to open, causing the level of the interface to drop until returning to the previous situation.

FIG. 4 illustrates the use of the method according to the invention for limiting the level in an enclosure by action on the liquid supply valve of said enclosure. In this figure, the elements identical to those of Figure 1 are identified with the same number assigned to the index "'. When the level in the enclosure 1" ^• is in AA', the condenser 8 * "is out of liquid, there is little or no condensation of the fluid passing through the condenser, the pressure on the diaphragm of the servomotor 32 is low, and the valve 31 allowing the supply of the enclosure is open. against, the level rises in BB ', the condenser is in the liquid; the fluid condenses, the trap 9 "'opens; the condensate flow increases the pressure on the diaphragm of the actuator, and causes the valve to close, thereby stopping the supply of enclosure 1 "'.

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Claims

Patent claims

1. A method for controlling the level of a liquid contained in an enclosure, said method consisting in continuously supplying a condenser placed in said enclosure, by a fluid brought to the gaseous state under pressure p, and being at a temperature tl, greater than the temperature t2 of said liquid, said fluid being capable of condensing at said pressure p and at said temperature t2, said method comprising the following steps t

A) the condensation of said fluid in said condenser when the level of the liquid in the enclosure is such that said condenser plunges into the liquid and said fluid is therefore at temperature t2,

- b) the evacuation of said condensed fluid, out of the condenser, said evacuation causing, under the effect of the pressure of the condensed fluid, the withdrawal of the liquid contained in the enclosure from said enclosure, and / or the stopping the supply of liquid in the enclosure,

- c) stopping the evacuation of said fluid from said condenser, causing the withdrawal of said liquid to be drawn out of the enclosure, and / or the resumption of supply to the enclosure, when the level of the liquid contained in the enclosure is such that the condenser is located outside the liquid, and therefore at a temperature above t2, such that said gaseous fluid no longer condenses therein,

- d) repeating steps a) and b) as soon as the condenser plunges back into the liquid.

2. Method according to claim 1, characterized in that the liquid and the fluid are identi¬ c, and are constituted by water.

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3. Device for implementing the method according to one of claims 1 or 2, for controlling the level of a liquid contained in an enclosure, said device comprising:

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a condenser placed in said enclosure, said condensate being equipped with a supply of a fluid brought to the gaseous state,

1.0 - an evacuation device connected to said condenser capable of evacuating from said condenser the fluid condensed in the condenser,

- a system for controlling the flow of liquid to and / or

15 outside said enclosure, said system, connected to said discharge member, being controlled by the condensed fluid discharged from the discharge member.

4. Device according to claim 3,

20 characterized in that the discharge member consists of a thermostatic trap.

5. Device according to one of claims 3 or 4, characterized in that the flow control system is a system consisting of:

- by an automatic valve installed on the liquid withdrawal line from the enclosure, and connected: a) to the supply of fluid brought to the gaseous state, 0 b) to the evacuation member, c) to an ejector,

- And by a line to draw the liquid out of the enclosure, said line being itself connected to the line 5 connecting the automatic valve to the ejector.

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6. Device according to claim 5, characterized in that, in the automatic valve, is provided a calibrated orifice for discharging the liquid condensed in the condenser.

7. Device according to one of claims 5 and 6, characterized in that the discharge member and the automatic valve form a compact assembly.

8. Device according to one of claims 3 or 4, characterized in that the flow control system comprises an automatic valve installed on the liquid supply line of the enclosure, controlled by a servomotor sensitive to the condensation of the fluid.