US2607192A - Shut-off arrangement for mercury vapor systems - Google Patents

Description

Aug. 19, 1952 Q, WOOD TA SHUT-OFF ARRANGEMENT FOR MERCURY VAPOR SYSTEMS Filed May 31, 1951 AIR REMOVAL 16; AIR REMOVAL l XX): 20 Marco/er sum m H k l lla Inventor's: Orla L.Wood, Harold Nhackett,

' Their Attorney.

Patented Aug. 19, 1952 UNITED STATES; PATE SHUT-OFF ARRANGEMENT FOR VAPOR SYSTEMS Orla L. Wood, S che Hackett, Ballston, Electric Company,

NT. OFFICE.

MERCURY nectady, I and Harold N. Y.,' assignors to General a corporation of New York Application Mayer, 1951, serial No. 229,148

This invention relates to mercury vapor power-plants, particularly to an arrangement for disconnecting a component from a mercury vapor system without permitting ineleakage of air into the system and without the necessity-for shutting down the entire plant.

One of the few binary fluid cycleswhich has taken to preserve the purity of the-mercury.

Even though the system is'thoroughly cleaned before being put into operation, it is foundthat the mercury inevitably picks up a substantial amount of, dust and other dirt particles; and inspite of the exercise of greatest caution there will be a-certain amount of leakage of air into the system with. the resulting accumulation of dirt during normal operation of the power plant. This makes it'necessary to provide means for continuously removing whatever dust-and other dirt particles may accumulate in the system.

One way to eiTect this continuous, removal of dirt from the mercury system is to create a vacuum in the mercury sump sufilcient to'elfect evaporation of some of the mercury, the evaporating vapors serving to carry all the impurities to an air removal cooler" where the mercury vapor is condensed and the non-condensible picked up in the boiler, turbine, etc. is drained to V which is sealed air-tight gases are drawn oil by an air removal vacuumpump. This type of cleaning system is disclosed in United States Patent 2,196,003, issued in the name of O. L. Wood on April 2, 1940, and assigned to the same assignee as the present application.

In connection with such a cleaning system, a

further problemarises from the necessity for I periodically removing the accumulated impurities from the air removal cooler. 'Itis, of course, highlydesirable that this be accomplished without completely shutting down the mercury turbine power plant.

Accordingly, an object of the present invention is to provide an improved mercury cleaning system of the type described having special means.

for effecting isolation of the air removal cooler 5 Claims. (01. -36) 2 r so that it may be opened and cleaned without shutting down the entire plant.

A further object is to provide an isolating arrangement of the type described which does not depend on mechanical valves to seal the vacuum, yet-is capable of positively preventing the en-. trance of air into the system during the process of isolating and cleaning the air removal cooler.

Other objects and advantages will become apparent from the following description taken in 7 connection with the accompanying drawing in which the single figure represents diagrammatically a mercury turbine power plant having means for isolating the air removal cooler in accordance with the invention.

Generally, the invention is practiced by providing in each-vacuum conduit connected to the air removal cooler a U-shaped trap, with special means for filling and draining these liquid seals when it isdesired to isolatethe air removal cooler.

Referring now more particularly to the draw ing, the invention is illustrated as applied to a mercury turbine power plant comprising a mercury boiler I supplying motive fluid to a turbine 2, the exhaust from condenser-boiler pose of generating steam for driving a steam turbine or for other purposes. 7

Liquid mercury collecting in the bottom of the condenser boiler 3, together with dirt particles that maintained in the condenser-boiler 3. This 7 higher; vacuum in the sump is produced by a conduit 6 connected directly to cooler I, and causes some of the liquid mercury in the sump to flash into vapor and be drawn oil to the cooler, carrying with it the dust and other dirt' -which accumulates on the surface of the 1iquid,mercury-in the sump. Thus, the sump serves the double purpose of separating the dirt or dust from the mercury and as a reservoir supplying the boiler feed pump 5, which returns liquid to the boiler I through the feed conduit 5a.

In accordance with the invention disclosed in the above-identified patent to Wood 2,196,003, the dirt or dust is removed from the mercury sump 4 by way of a vacuum conduit 6 communicating with the air removal cooler I as described above. Similarly, air and entrained gases separating in the condenser-boiler 3 may which is condensed in a" 3,-which also serves the purin the cooler i eiiects condensation of the mercury, which falls to the bottom of cooler I and is drained through the return conduit H having a U-seal I la. The remaining uncondensed gases are drawn off through conduit 42 having a valve {2a to the air removal vacuum pump l3, which discharges to atmosphere through a suitable vent H. To provide access for cleaning the cooler I, a removable clean-out door It is provided. This i carries an atmospheric vent having .a, manu-.

ally controlled bleed valve ll. A vacuumgaugeei I8 is located convenient to the valve I! so that the operator can bring the air removalco'oler: to atmospheric pressure at a desired rate, andc so that the access opening cover [5 will not be removed until the pressure inside the cooler .7 is atmospheric.

In accordance with thein'vention, each vacuum" line connected to the cooler l, specifically-the vapor draw-air Y conduits 6, 8, are provided with U-seals 19', 23 respectively; During normal" oper-- ation; these U-scals" are kept free of condensed liquid by a gravity drain conduit -2| having branches connecting the lowermost portion of each U-seal with the interior of the cooler -!,or

with some other portion of the system to which the sealing. liquid canldrain when the manual shut-offvalve 22 is opened. It willbe obvious that the arrangement of the U-sealsand the sump l 'must be such'that in normal'operation the liquid level in the sump never rises highenough to enter the U-s'eals' from the cooler 1;

The means for filling the liquid'U-seals comprises an elevated supply tank 23 containing liquid mercury maintained at atmospheric pressure by the vent 2t. A gage glass 25 or-equivalent liquid level indicating means shows the levelof mercury in the reservoir 23. The mercury used to seal the vacuum conduits 6,8 is returned to the-reservoir 23by a return conduit-26 communicating with the boiler feed conduit 5d, and

containing a valve 27. Sealing liquid is supplied from reservoir 23 by way of a. conduit 28 containing a valve 29'. This: conduit 28 may conveniently be connected to the branched drain conduit 2!- as clearly shown in the. drawing.- It

is to be noted that the supply conduit 28 is provided with a U-seal28a;

The manner in which this system is employed to positively isolate the air removal cooler 1 without using any mechanical valves in the vacuum conduits will-be seen from the following.

When it is desired'to clean out the air removal cooler I, the seal drain valve 22" is closed, and the seal liquid supply valve 291 opened'so that liquid mercury flows from the reservoir 23 through conduit 28 to fill the U-seals I9, 20, until the shorter legs 19b, 20a, are filled and liquid beginsto overflow into the cooler 'l.- The air removal pump valve I2 is then closedand the bleed valve I! opened to slowly admit air from the atmosphere to' cooler 1. As thepressure in cooler 1 builds up to atmospheric, the liquid mercury in the U-seals I9, 28 rises in the comparatively long right-hand legs- Ma, 2112)} until the heightof the mercuryfcolumn in'these legs is sufiicient to balance the vacuum existing in the mercury system during normal operation. This mercury column in the U-seallegs 19a; 206, thus preserves the normal vacuum .in the mercury sump 4 and the condenser-boiler 3, and the mercury vapor power plant can continue to operate while the clean-out door 15 is removed and the accumulated dirt removed from cooler l. Similarly, the U-seal Ha seals the drain conduit H.

To put the air removal system back into service, the clean-out door cover i5 is. replaced and the bleed valve ll closed. The vacuum pump valve l2a' is then opened and the pump I3 brings the air removal cooler 1 down to the normal vacuum on the system. The valve 29 is then closed and the scal'drain'valve ZZopened so that the liquid in' the. U -seals I9, 2%) flows into the cooler 1 through drain conduit 2 L This, of course, means that thetotalamount of mercury in the system has, been increased by the amount employed to seal the traps I9, 28. In order to return the amount of-working fluid to its normal value, valve 21 is opened and mercury from the boiler feed conduit 5c permitted to flow back into reservoir 23 until the level therein, as indicated by. gage 25, returns to its {previous normal value."

While it is'tr'ue that, during normal-operation, some-air may leak into cooler 1 through the" mechanicalvalve [1, any such leakage-air will be"? directly expelled'by pump1l'3. During the process of isolating cooler I and cleaning the'dirt therefrom,'the cooler is entirely isolated from the vacuum: parts of 'the ,systemtby liquid-filled" U-seals, no-mechanical valves being present to: introduce the possibility that dirt may prevent'i the valves-from seating tightly and-thereby per=' mit air to enter the system:

Itwill be' seen that the'invention provides a mechanically simple arrangement for effectively I sealing the-vacuum 'lines of a mercury'vap'or powerplantin-orde'rthat one component thereof" may be removed from the system for cleaning or other maintenance purposes;

While only one embodiment of the invention? has been described specifically herein; it will be apparent to thoseskilled in the artthat many: substitutions of equivalents andmodifications":

It is, of course, desired to cover by theappendedclaims all such changes as fall,

may be made".

within the-true spirit and scope of the invention.

What-we claim-as new-and desire to secure by Letters Patent of the United States is:

1. Ina mercury vapor powerplant having in series a boiler feed pump, mercury boiler, turbine, condenser-boiler, and mercurysump maintained under-vacuum by "a second pump for removing non-condensible gases from the system and an' air removal cooler connected-in series between the vacuum pump and the condenser-boiler'and betweenthe vacuum pump and the sump respectively, the combination of means for isolating the air removal coolerfrom the vacuum portions of the ystem comprising a first conduit for draw-' ing off hon-condensible gases from the condenserboiler and including a first U-section, .a second conduit' fo'r drawing .off non condensible gases from the sump and including'a second U-section, the lowermost portion of said U-sections being above the bottom of the air removal cooler and connected, thereto by a gravity .drain conduit,

first shut-01f valve means in said drain conduit, an elevated mercuryreservoir vented to-atmos--- phere and connected by a seal supply conduit. to

said drain conduit between the shutofi valve and Y the U-sections, said seal supply conduit including a third U-section and a second shutoff valve between the third U-section. and the reservoir, a seal liquid return conduit for bleeding mercury-.- from the boiler feed pump back to said reservoir,

third valve means in said seal liquid return conduit, and valved vent means for bringing the air removal .cooler up .to atmospheric pressure,

whereby the air removal cooler may be isolated supply valve to fill all three U-sections, after which said valved vent may be opened to'break thevacuum in the air removal: cooler, the cooler being returned to serviceby closing the seal liquid supply valve and opening the drain valve to empty the first and second U-sections into the cooler after which the quantity of mercury in the system may be restored to normal by opening said third valve to admit mercury from the feed pump to the seal liquid reservoir.

2. In a mercury vapor powerplant having in series a boiler feed pump, mercury boiler, turbine, condenser-boiler, and a mercury sump maintained under vacuum by a second pump for removing non-condensible gases from the system and an air removal cooler connected in series between the vacuum pump and sump, the combination of means for isolating the air removal cooler from the sump comprising a conduit for drawing ofi non-condensible gases from the sump and including a U-section with one leg connected to the air removal cooler, a gravity drain conduit connecting the lowermost portion of said U-section with the air removal cooler, first shutoff valve means in said drain conduit, an elevated mercury reservoir vented to atmosphere and connected by a conduit for supplying sealing liquid to the U-section, the seal supply conduit having a second U-section and a second shutoil valve, and valved vent means for bringing the air removal cooler up to atmospheric pressure, whereby the cooler may be isolated from the sump by closing'the gravity drain valve and opening the seal liquid supply valve to fill said U-sections, after which the valved vent may be opened to break the vacuum in the air removal cooler, the cooler being returned to service by closing the seal liquid supply valve and opening the gravity drain valve to empty the first U-section into the cooler.

3. In a mercury vapor plant having in series a boiler feed pump, a mercury boiler for enerating mercury vapor under pressure, a mercury vapor energy consumer, a condenser-boiler and a mercury sump maintained under vacuum by a second pump for removing non-condensible gases from the system, and an air removal cooler connected in series between the vacuum pump and the sump, the combination of means for isolating the air removal cooler from the sump comprising a vacuum conduit for drawing off non-condensible gases from the sump and including a U-seal sec- :tion, the lowermost portion of said U-seal being above the bottom of the air removal cooler and connected thereto by a gravity drain conduit, first shut-off valve means in said drain conduit, a mercury reservoir located substantially above the level of the air removal cooler and vented to atmosphere, a seal liquid supply conduit for conducting liquid from said reservoir to the lowermost portion of said U-seal, said seal supply conduit including a second U-seal and a second shut-oil valve between the second U-seal and the reservoir, a seal liquid return conduit for bleeding mercury from the high pressure side of the system back to the seal liquid reservoir, third valve means in the seal liquid return conduit, and valved vent means for bleeding air into said .cooler for bringing the pressure therein up to atmospheric, whereby the air removal cooler may be isolated from the mercury sump by closing said first drain valve and opening the seal liquid supply valve to fill said U-seal sections, after which said valved'vent may be opened to break the vacuum in the air removal cooler, the cooler being returned to service by closing the seal liquid supply valve and opening the drain valve to empty the first U-seal into the cooler, after which the quantity of mercury in the system may be restored to normal by opening said third valve to admit mercury from the high pressure portion of the system to the seal-liquid reservoi'rj I 4. In a thermal energy transfer and conversion system having hydraulic circuits filled with a vaporizable liquid the purity of which must be carefully preserved by continuously removing dirt therefrom during normal operation, said hydraulic circuits including a liquid sump maintained under a substantial vacuum by an air removal pump and having an air removal cooler in series between the pump and sump, the combination of means for isolating the air removal cooler from the sump comprising a vacuum conduit, for drawing off non-condensible gases from the sump and including a U-seal section, the lowermost portion of U-seal being above the bottom of the air removal cooler and connected thereto by a gravity drain conduit, first shut-off valve means in the drain conduit, a liquid reservoir located substantially above the level of the air removal cooler and vented to atmosphere, a seal liquid supply conduit for conducting liquid from said reservoir to the lowermost portion of the U-seal, the seal supply conduit including a second U-seal and a second shut-off valve, and valved vent means for bleeding gas into the cooler for bringing the pressure therein up to atmospheric, whereby the air removal cooler may be isolated from the sump by closing the gravity drain valve and opening the seal liquid supply valve to fill said U-sections, after which the valved vent may be opened to break the vacuum in the air removal cooler, the cooler being returned to service by closing the seal liquid supply valve and opening the drain valve to empty the first U -seal into the cooler.

5. In a thermal energy transfer and conversion system having hydraulic circuits filled with a vaporizable liquid the purity of which must be carefully preserved by continuously removing dirt therefrom during normal operation, said hydraulic circuit including a liquid sump maintained under a substantial vacuum by an air removal pump and having an air removal cooler in series between the pump and sump, the combination of means for isolating the air removal cooler from the sump comprising a vacuum conduit for drawing off non-condensible gases from the sump and including a U-seal section, a drain conduit communicating with the lowermost portion of the U-seal, first shut-off valve means in said drain conduit, a source of liquid located substantially above the level of the U-seal, a sealing liquid supply conduit for conducting liquid from said reservoir to the U-seal, the seal supply conduit including a second U-seal and a second shut-off valve, and valved vent means for bleeding gas into the cooler to bring the pressure therein up to atmospheric, whereby the air removal cooler may be isolated from the sump by closing the drain valve and opening the seal liquid supply valve to fill said U-seals, after which the valved vent may be opened to break the vacuum in the air removal cooler, the cooler be- 7 ingtrebfirned try-service by. closing the'seal liquid' Number supply I valve andmpenin'g the drain valve. 1,436;174' ORL'A'L. WOOD; 2,121,599

HAROLD N HACKETT. 2,196,003

, k 5 v REFERENCES CITED Thgfollowing references-are of recordinth murlber 9, fil p th'i'syatent: 2 2 32 v UNITEDSTATES PATENTS 1D 70.53271 Nuniber Name-" Date 906,312 Shaw Dec. 8, 1908' Name. Date Johmsson Nov;21 ,1922" Kilgoreet; a1 June 21;1938} Wood Apr."2,'1910" FOREIGN PATENTS Country Date" -Grea-t Britain July '4; 1932' France Sept. 29;1925

Germany Apr. 22 1941-

Images