US1679678A - Ventilating device for tank vessels - Google Patents

Description

Aug.A 7, 1928.

`.'l. MULDER ETAL VENTILATING DEVIQE FOR TANK VESSELS Filed Sept. 24, 1924 Patented Ang.` 7, 192s;

UNI-TED- ST1-Ares PATENT OFFICE.

JAKOB MULDER AND DIRK CHRISTIAAN ENDERT, JR., OF ROTTERDAM, lNE'1?HERLANDS.

Vv1nIYTILAfrIrI'etIJEvIcE Fon 'rank vEssELs.

Application mea `september 24, 1924, serialvzn. 739,747, andan the Netherlands september 2s, 192e.

Onltank vessels or'the transport of'volatiley oils such fas petroleum, petrol and the like, the tanksand pipes or ductscannot be so completely emptied by the pumpsthatno l gases and liquid residuals remain behind.' If such gases and residuals `are not removed they constitute a'continuous danger :from explosions. -Dierent directions have been given'therefore that in suchtanksno repairs l or other work maybe carried out, so longas they have not been made entirely free `oit' gases. From the aforesaid it follows that in emptying the tanks care should be taken `that the liquid residualsl shall be eva orated and l5 thatthe vgases are removed as quickly as p osvsible. Hitherto the tfreeingof the tanksv from gases `was accomplished by either of the following methods z.

l. The introduction of steam near thel bottomof the. tanks wherebyxthe'gases were driven out through the Open hatches or doors. 2.-'lp`he use of; cooling sails. long tubesof cloth which are brought with 251theirwlowcr'ends intoth'e tank throughthe vopen doors of the hatches, their uppery ends beingv provided with wind catching valves.

Theswind caught by these valvesis driven into the tank through. the vtubular("cooling7V y y duces the danger of fire or of explosions, be-

'sa1ils and drives-the gases 'out'th'rough the n z,hatch doors into theatmosphereg. The driving out yof they gasesby means Qcooling sails "makes itnecess'ary to entirely open the largedoors of thetanks which must bedone whilst the tankis possibly stillfilled with combustible gases.' The opening `of these large tank doors is cuifnbersome and requires vmuch time and labour.

5. usualgas ejectors the lowerv end of These n are l vv"small yport, holes provided'k in the said doors, fthe danger of lire is nevertheless not coml Y l Moreover it' lispossible thatjfor the opening"v of these doors- 40 toolsl areused suchas steelhammers and thev the tube should remain at a considerable distance'from the kbottom of the tank, since these y eject-ors do not-.produce a sufticient vacuum to suck ofi" liquids in4 addition to the gases. (In connection with a possible list of the tank vessel, the said distanceshould amount to about 20 cm.) f The consequence is that after the sucking off operation a great part of the n heavy gases will remain behind on the bottom of the tank. With the methody hereinafter -described and forming the 'subject of the present 'invention this difficulty does not present itself, because the lower end of the suckin tube is only at a very small distance from t e bottom of the tank (about 2 'cm.). Furthermore the capacity 'of the suckingapparatus is so large. that at the endet the process the air in the lower part of the tank isso stirred up that it mixes with the heavy gases in the lower part of the tank, the mixture being completely sucked olf-even from the remotest parts of the tank. In the case of the methods used up to now, it was'necessary afterthe gasesI had beensucked off by means of ejectors to apply the cooling sails Although the use of ejectors for the .suck-V ing ofi' of the gases already considerably re- 80 cause 1t 1s not necessary to completely openA f the largeV tank doors, but only to open the pletely excluded, for if it is desired to obtain' a completey removal of lthe gases, it is linevitable to put lthe cooling sails to work after theejectors have lbeen used,when it is necessary to completely removef the tank doors' with which theabove mentioned objec- 'tions are connected and further with the use of the cooling sails the objection always exists that combustible gases mustv be carried off into the atmosphere, with the'oonsequent' danger ofiire.A p

The above described methods hitherto employed -are moreover very inefficient, since the removal Aof the gases by these methods Itakes much timerand depends uponV atmospheric conditions. The usual gas-ejectors a.. al)

have a relatively small capacity and the cooling sails are especially inetiicient in the case of calms.

The cooling sails moreover have the objection that they only commence working after the heavy gases have been sufficiently mixed up with air, Which from the nature ot things consumes still. more time.

Besides the said methods do not provide means lfor removing the liquid residuals from the pipes or chiots for which purpose up to non7 steam has been introduced into the chiots, which method takes a great deal of time and besides is not always eiiicient. Experience has shown that the majority of accidents occur When repairs are carried out in ducts or valves, even. for Weeksatter the certiti` cates for freedom oi gas have been. passed. Moreover, the small gas-ejectors in the tanks could only ereatea very small vacuum and tests have proved! that an increased vacuum greatly improves the evaporation ot benzine or spirit oils. `With the neu7 method a much higher vacuum can be obtained.

The invention has not only i'or its purpose to do avvay with the above said objections and to make the tanks ifree of gas in a: very short time, but also to `provide means 'for making the Whole system of pipes, ducts, valves and pumps completely tree ot gas in a simple manner. 1

To this end and according to this invention the gases are sucked oil from the oil tanks through the same chiots which are used tor lilling or emptying the said tanks.

lin the accompanying drawings whichl illustrate apparatus adapted for use in carrying out the invention,

F ig. l is a side view of a portion of a tank vessel., 1

Fig. 2 is asimilar vievv, but on a smaller scale, of a typical tank vessel.

Fig. 3 is a plan view of a hatch cover and Fig. 4i is a vertical section through the same.

ln the drawings the several compartments which are indicated by the numerall are provided with oiltilling and discharge ducts 2 and an oilI pump 3, which parts may be of any usual or desired construction. l The air or gas ejector l is coupledy to a. duct system in series with and at the exterior side of the oil pump 8, and to a. steam line 5 in theY vot a large capacity air or gas ejector t'o the oil duct system.

By opening and closing the several val'ves 4 the contents of each tank may be sucked oli through its inlet and outlet duct, atmospheric air entering through the openings of the tank doors.

In some cases use can be successfully made of air directing surfaces or the like for guiding the air entering the tank and ensuring the most eilicient distribution thereof.

Where the oil gases are specifically heavier than air, the method employedr according to the invention also has the advantage that the gases aresucked off from the lowest point of the tank, .Where also thegreater part of the liquid residuals have remained behind. These .residuals are fromA the -beginning of the operation exposed t'o a strong. current of air, so that they will qiuickl'yevaporate.

The generatedA vapors do not. first disperse in the room of the tank, aswast'he case With the methods usual up to now but ared'irectly sucked off through the ducts..

AnotherV advantage of the invention is that the lillingsand-emptying pipes or ducts are at the same time made4 completely vfree ot gas. By opening and closing. the several val-ves the current of air, can be made to pass through all thev ducts and alsothe pumps, so that the safety ot the vesselv and et the persons in the case ot forth-coming rcpairsis much better guaranteed thanVWl-ien using any of the oldermethods. A

When the invention is carried-out by the use of ejectors, the further advantagev is obtained that the gases sucked 'oilv are intimately mixed with theV steam of theejeetor and are rendered incombustible.

From the toregoing 1t Wall be 4clear that the invention, makes itr possible tosuck' oit the gases in a veryl Vshort time and thatfthe removal of the undesirable gases, 'vvilljbe complete. v. j i l Besides this removal is done in an absolutely safe Way and' requires loutffevv men.

What We claim is :v

' .-1 f l. In the process of removing-residualy pump system volE the tank,=the' step which j comprises establishing thesuction in series With and at the exhaust` side ofthe! pump, whereby the pump and the-,ductsexternal thereof. may be freed from gases.

2. The method of removing., gases from -1 tanks having a. permanent pump and: duet system for supplying` liquid tlieretofland Withd awing the same: therefrom,l ywhich comprises establishing asuctjion at the' out-v let sideof said pump, Wherebygases are'rew movedv from said tank V'andair may ibvv into the same, and directing the `iI1`com'ing'1-a`ir laterally of said tank to sweep tliegasesto- Wards the duct inlets.'F

3. In a tank vesselg, the1coiriloiiiationfV of'a.-

tank,a liquid pump and' ducts for supplying and withdrawing liquid thereto, of an air or laterally of said tank, and ducts for supl1 gas ejector connected inseris with and eX- plying liquid to and withdrawing the same ternally of said pump for freeingthe tanksv from said tank,"of al large capacity ejector n pump and ducts of gases after the liquid has connected to said ducts for exhaustlng gases 5 been withdrawn. from said tank. y

4. In a tank vessel, the combination with In testimony whereof we have hereunto 15 a tank for holding liquid, a cover for said set our hands. v tank having ports therethrough, baiiles be;- J AKOB MULDER. low said ports for directing air currents DIRK CHRISTIAAN ENDERT, JR.

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