GB2112291A

GB2112291A - Automatic cistern

Info

Publication number: GB2112291A
Application number: GB08138212A
Authority: GB
Inventors: Yoshiteru Sonoda
Original assignee: Fujikin Inc
Current assignee: Fujikin Inc
Priority date: 1978-08-02
Filing date: 1981-12-18
Publication date: 1983-07-20
Also published as: SE7903743L; GB2112291B

Abstract

An automatic cistern has two chambers connected by a channel. A valve is operated by a float in the first chamber and the cistern includes magnetic latching means for retaining the valve in an open position. The first chamber may be raised to a pressure greater than in the second, and when liquid enters the first chamber the float rises and becomes latched open. When the first chamber is then emptied into the second chamber pressure is equalised and the valve is unlatched and closed.

Description

SPECIFICATIONS Automatic cistern This invention relates to an automatic cistern.

The cistern may form part of an apparatus for removing an entrained vapour from a gas in which the cistern receives condensed vapour and automatically empties when a certain quantity of liquid is collected. The apparatus may for example be used for removing water vapour from a compressed air supply to a paint spray.

According to the present invention there is provided an automatic cistern which comprises first and second chambers interconnected by a channel, having a valve operated by a float in said first chamber, latching means adapted to retain said valve in the open position, unlatching means adapted to cause the valve to close, and means for maintaining said first chamber at an elevated pressure relative to said second chamber; whereby in use liquid entering the first chamber causes the float to rise until the valve becomes latched in the open position and whereby emptying of the liquid from the first chamber into the second chamber causes a temporary equalisation of pressure which causes the valve to be unlatched and hence closed.

A detailed description of one embodiment of this invention is given hereinafter referring to the accompanying drawings wherein:~ Figure 1 is a vertical sectional front view of a dehumidifier including a cistern according to this invention; Figure 2 is a vertical sectional side view of the dehumidifier; Figure 3 is a vertical sectional view of the automatic cistern with the float raised.

Figure 4 is a vertical sectional view of the cistern of Figure 3 wherein pistons included therein have pushed down a float.

A cylindrical container 1 is made of either a metal or a plastics material. Cold worked nylon is particularly suitable, because it is highly resistant to pressure and acids. Disposed within said container 1 is a heat exchanger tube which has on its outer abd inner surfaces spirally disposed fins. A flange portion on the upper part of the heat exchanger tube 2 has a radially disposed gas inlet 1 1 and a gas outlet 12 which are disposed substantially along a common axis.

The upper part of the container 1 terminates in a flange which in use abuts the flanges of the heat exchanger tube 2, a union nut 14 urges said flanges into sealed abutment, which is assisted by an O-ring 51 disposed therebetween. Hence between the inner surface of the container 1 and the outer spiral fin of the heat exchanger tube 2 a spiral cooling passage A is formed. The cooling passage A extends from said aforementioned gas inlet 1 1 toward the top of the device to a drain receptacle E at the bottom thereof.

An insulating tube 7 is disposed to contact the inner fins of the heat exchanger tube 2 thereby to form a spiral cool gas passage B between the inner fins of the heat exchanger tube 2 and the inner surface of the insulating tube 7. The cool gas passage B extends from a cool gas outlet 17 disposed at the top of the exchanger tube 2. The cool gas outlets 17 discharge gas along line perpendicular to a line connecting the gas inlet 1 1 and the gas outlet 12, and fitted with a silencer 16'. Toward the upper end of the insulating tube 7 a gas exhaust part 20 interconnects with the gas outlet 12. In order to ensure a gas-tight seal above and below the gas exhaust port 20 O-ring 52 and O-ring 53 are disposed respectively between the tube 7 and the exhaust port 20.

It is desirable that the insulating tube 7 be thick enough to prevent thermal diffusion. As will be described in more detail later, the outer surface of the insulating tube 7 effectively forms a first heat exchanger and the inner surface thereof forms a second heat exchanger. So the diffusion of thermal energy between them must be suppressed as far as possible. A thin vortex tube 4 is also inserted into the insulating tube 7. Thus four tubes; the container 1 , the heat exchanger tube 2 the insulating tube 7 and the vortex tube 4~are all coaxially disposed, the former three tubes 1,2 and 7 are each in contact with an adjacent tube, but the vortex tube 4 is isolated except at either end.

The inner space of the vortex tube 4 forms a vortex passage C where a rapidly rotating vortex flows gradually upward. The space between the vortex tube 4 and the insulating tube 7 forms a heating passage D.

A junction body 5 is fixed to the bottom end of the heat exchanger tube 2 thereby to interconnect the drain receptacle E and the three passages B, C or D.

A filter 13 covers the bottom of the junction body 5. The filter 13 is fixed to the outer surface of the heat exchanger tube 2 with a filter band 22, and is secured to the junction body 5 with screws at its lowermost extremity. The junction body 5 forms a sealed abutment with the lower horizontal and inner cylindrical surface of the heat exchanger tube 2, by means of an O-ring 55 and an O-ring respectively. The junction body 5 incorporates two jets g, two ascending passages k, a descending passage f, and bifurcate passages h.

The jets g are tangentiaily disposed at the lowest part in the vortex tube 4 and discharge into the vortex passage C. Gas is thus tangentially supplied to the vortex passage C from the jets g and forms a rapid vortex flow which ascends the vortex tube 4 in vigorous rotation. The ascending passages k are connected with the lowest end of the heating passage D. Gas rising from the ascending passages k into the heating passage D receives heat for the vortex tube 4 and the temperature thereof rises during ascent of the said passage.

The descending passage fconnects the lowermost end of the vortex passage C to the bifurcate passages h. It will be appreciated that in general rapid vortex flow is formed in the vortex passage C. Thus the cooler gas in said passage C tends to move, by virtue of the vortex, to the axis of the passage C and hotter gas is separated toward the outer surface thereof. The hotter gas in the outer part will continue to rise, but the cooler gas near the centre begins to descend by reason of its higher specific gravity. The cooler gas therefore enters the descending passage f, rises through the bifurcate passage h and rises up to the cool gas passage B.

A cylindrical screw threaded body 16 connecting the lowest end of the vortex tube 4 and the upper face of the junction body 5. A cap 24 is disposed upon the upper end of the vortex tube 4, which cap has a narrow borejin the upper thickness thereof.

Above the cap 24 an outlet 25 for hot gases is provided. This comprises an exhaust valve 6 for the hot gases. The exhaust valve 6 is fitted about the male screw at the top of the insulating tube 7 and secured by locking nut 23. The valve body 19 acts to pen or shut the outlet 25 as desired.

Figure 1 shows the valve 6 in the open state and Figure 2 shows the exhaust valve 6 in the closed state.

The exhaust valve 6 terminates in a silencer 18 The reason that silencers 16' and 18 are fitted upon the cool gas outlet 17 and the hot gas exhaust valve 6 is both to maintain the high pressure state in the respective tubes and to suppress noise. The pressure loss caused by both silencers must be carefully adjusted to allow the rapid flow of gas in the vortex tube 4 and for optimum operation of the process.

The automatic drain trap 3 will now be explained, with particular reference to Figures 3 and 4 of the drawings. A drain hole 29 is formed at the bottom of the container 1 of the dehumidifier. Of course it is possible to fit it with a drain valve and to open the valve occasionally to empty liquid from receptacle E. However, in this example an automatic drain trap is furnished which stores liquid and can exhuast it automatically when it exceeds a predetermined level. The drain hole 29 is contiguous with an inlet bore 33 and an opening 39 which allows access to the first drain chamber M, which contains a light float 31. Between the exterior casing of the trap 3 and the interior casing 40 a second drain chamber N is formed.At the centre of the base portion of the interior casing 40 an outlet is disposed, into which a valve base section 41 which is an upper part of a sleeve 37, is inserted.

The valve base section 41 is cylindrical and a valve bore 42 is bored through a side surface.

A valve body 36 is fitted into the valve base section 41 and acts to open or shut the valve bore 42. The top of the valve body 36 is held loosely in an axial recess of the float 31. When the float 31 falls, the valve body 36 is pushed down. However when the float 31 goes up beyond a certain level, the valve body 36 is pulled up by a rim 43 of the float 31. Thus, the valve body 36 accompanies the float 31 with some hysteresis, by virtue, inter alia, of a magnet 34 which attracts a ferromagnetic material 35 fixed upon the top surface of the float 31. Pistons 32 are also provided, and these are free to move axially up or down. Ordinarily the first drain chamber M is at high pressure and the second drain chamber N is under atmospheric pressure.In this instance the pistons 32 are pushed up as shown in Figure 3, because the space above the piston 32 interconnects with the second drain chamber N through a narrow passage S.

At first, in use, the float 31 is at its lowest level and the valve body 36 shuts the valve hole 42.

The pistons 32 are set at their highest level by the pressure difference. Liquid drains from the dehumidifier through the drain hole 29 and opening 39 into the first drain chamber M and is stored there. As the stored quantity of the liquid increases, the float 31 rises slowly by virtue of its buoyancy.

When the ferromagnetic material 35 approaches the magnet 34 nearer than a predetermined distance, the magnetic force becomes stronger than gravity and the float 31 attracted by the magnet 34 suddenly rises momentarily. Figure 3 shows such state. Now the rim 43 of the float 31 pulls up the head of the valve body 36 and the valve hole 42 opens. The liquid flows from the first drain chamber M into the second drain chamber N and is exhausted from the exit 45 of the sleeve 37.

When the first liquid chamber M is evacuated, the first and the second drain chamber M and N become effectively continuations of each other and their pressures are therefore equalized. Thus the force holding up the pistons 32 vanishes, and the pistons 32 fall by their own gravity and pushes down the float 31, Figure 4 shows such a transient state. The float 31 falls and the valve 36 shuts the valve hole 42. When the liquid from the second chamber N is almost evacuated air from the second chamber N escapes into the atmosphere, thereby equalizing the pressure of the second chamber N with atmospheric pressure.

Then the pistons 32 begin to rise acted upon by a larger pressure from the first chamber M.

In use of the whole device compressed gas is introduced into the gas inlet 11. The compressed gas entering the inlet 11 under pressure enters the spiral cooling passage A and is gradually cooled going spirally down the passage A. In this instance the cooling medium is the cool air in the cool gas passage B. As the gas under a normal atmospheric pressure is compressed, the partial pressure of aqueous vapour increases in proportion to the compression rate and approximates to the saturated aqueous vapour pressure at this temperature. The gas in the semi-saturated condition is cooled, so the saturated aqueous vapour pressure decreases to a value lower than the partial aqueous vapour pressure of the gas.

The quantity of aqueous vapour which corresponds to the difference of the saturating pressure and the real partial vapour pressure at this temperature condenses and flows into the receptacle E from which it drops, and is stored in the chamber M. The gas then enters the filter 13 and a part thereof is forced at pressure through the jets g tangentially into the vortex passage C and begins a vigorous vortex motion.

As mentioned before, the hotter gas molecules tend to move to the outer surface of the vortex and cooler gas molecules tend to gather at the axis by the action of the vortex motion. The hot gas therefore rises, heating the gas in the heating passage D by raising the temperature of the outer walls of the vortex tube 4, the gas in the tube 4 then enters the silencer 1 8 of the hot gas exhaust valve 6 through the openingj.

The cool gas generated at the axis of the vortex passage C flows through the bifurcate passages h to reach the cool gas passage B. Here the cool gas passes through the spiral cool gas passage B, cooling the gas introduced into the cooling passage A by agency of the heat exchanger tube 2. Finally at the silencer 16' its pressure is reduced and the cool gas ejected from the cool gas outlet 17. Residual gas which does not pass into the jets g goes into the heating passage D through the ascending passage k. The gas rises there, is heated by the vortex tube 4 up to higher enough temperature than that of its dew-point and is exhausted from the gas outlet 12.

The exhausted compressed gas can be utilized for spray painting applications, for pneumatic tools and machines and may be incorporated in such machines. As the gas has most water eliminated therefore it has a low dew-point and contains little aqueous vapour.

By this invention substantially dry compressed gas can easily be made. Thus, no special cooling heating mediums are necessary, cool and hot gases separated from the compressed gas itself are utilized as such media. So its composition is simple, its heat efficiency is high and its operation is easy. Moreover the dehumidifier of this invention can be small and handy because the first and the second heat exchangers are disposed coaxially. Finally it is convenient for piping as the gas inlet 1 1 and the gas outlet 12 is set on a common axis.

Claims

1. An automatic cistern which comprises first and second chambers interconnected by a channel having a valve operated by a float in said first chamber, latching means adapted to retain said valve in the open position, unlatching means adapted to cause the valve to close, and means for maintaining said first chamber at an elevated pressure relative to said second chamber; whereby in use liquid entering the first chamber causes the float to rise until the valve becomes latched in the open position and whereby emptying of the liquid from the first chamber into the second chamber causes a temporary equalisation of pressure which causes the valve to be unlatched and hence closed.

2. A cistern according to claim 1 wherein said valve comprises a stem having an upper engagement portion for engagement in a corresponding recess in the float, whereby only when the float moves axially upwardly beyond a predetermined point will the engagement portion engage the float and hence cause the valve to open.

3. A cistern according to either of claims 1 or 2 wherein the latching means is magnetic.

4. A cistern according to either of claims 2 or 3 wherein the float has an upper magnetisable surface and the first chamber includes a magnet to latch the same.

5. Apparatus according to any one of the preceding claims 1 to 4 wherein said unlatching means includes a piston axially movable on equalisation of pressure to unlatch said valve.

5. A cistern according to any one of the preceding claims 1 to 4 wherein said unlatching means includes a piston axially movable on equalisation of pressure to unlatch said valve.

6. Apparatus for separating an entrained vapour from a gas including a cistern for condensed liquid as claimed in any one of claims 1 to 5.

7. An apparatus substantially as hereinbefore set forth with reference to and as illustrated in Figures 3 and 4 of the accompanying drawings.

New claims or amendments to claims filed on 22 Feb 1983.

Superseded claims. All.

New or amended claims:~

1. Apparatus for separating an entrained vapour from a compressed gas supply which comprises an inlet for the compressed gas, primary and secondary heat exchangers, means for separating part of the gas into relatively hot and cold portions means for applying the cold portion of gas as a heat exchange medium to the primary heat exchanger to cool the compressed gas;; means for applying the hotter portion of the gas as a heat exchange medium to the secondary heat exchanger to heat the compressed gas from which said vapour has been condensed, and supply outlet means for the compressed gas thus heated, and means for removing liquid condensed from said entrained vapour as a result of the cooling of the compressed gas including an automatic cistern which comprises first and second chamber interconnected by a channel having a valve operated by a float in said first chamber, latching means adapted to retain said valve in the open position, unlatching means adapted to cause the valve to close, and means for maintaining said first chamber at an elevated pressure relative to said second chamber;; whereby in use liquid entering the first chamber causes the float to rise until the valve becomes latched in the open position and whereby emptying of the liquid from the first chamber into the second chamber causes a temporary equalisation of pressure which causes the valve to be unlatched and hence closed.

2. Apparatus according to claim 1 wherein said valve comprises a stem having an upper engagement portion for engagement in a corresponding recess in the float, whereby only when the float moves axially upwardly beyond a predetermined point will the engagement portion engage the float and hence cause the valve to open.

3. Apparatus according to either of claims 1 or 2 wherein the latching means is magnetic.

4. Apparatus according to either of claims 2 or 3 wherein the float has an upper magnetisable surface and the first chamber includes a magnet to latch the same.