US2290038A - Insulated tank car - Google Patents

Description

July 14, 1942. C. H. FOLMSBEE 2,290,038

INSULATED TANK CAR I Filed June 14, 1940 INVENTOR (7y; H fiimskq LN ATTORN EY Patented July 14, 1942.

' INSULATED TANK CAB Clyde H. Folmsbee,

Ber-wick, la., assignor to American Car and Foundry Company, New

York, N. 2., a com.

tion of New Jersey Application June 14,1940. Serial No. 340,453

8 Claims.

This invention relates to tank cars in general,

and in particular to insulated tank cars of the relatively low pressure type for the transmission of liquifled gases. V v

.In the past liquified or highly compressed gases have been transported in comparatively small containers of extremely heavy, construction capable of withstanding the extreme pressure of the gas regardless of the outside or atmospheric temperature. In certain rare instances large containers for transport of liquiiled gases or highly compressed gases under the same conditions have been built but such con-. tainers in order to comply with I. C. C. regulations must be forged from a single billet. These large containers are manufacture and of enormous weight, in most instances having steel walls two to three inches thick but in some cases the walls are live to six inches in-thickness. It has also been proposed tures whose cost may be but a fraction of the cost of the forged structures, but all of these insulated structures heretofore built have required an excessive wastage of lading in order to maintain the lading at the necessary low temperature to prevent bursting of the container shell. It is an object, therefore, of the present invention to provide a wholly insulated tank car in which liquified gases may be transported for comparatively long periods of time without any loss of lading and with a very slight increase in temperature, in other words, with a minimum loss of energy.

A further object of the invention is the provision of a wholly insulated tank car of the medium pressure type complying fully with I. C. C. regulations and in which all metallic paths for heat loss from the tank shell are reduced to a minimum with the paths of small cross section and great length.

Another object of the invention is the provision of a wholly insulated tank car with a iully insulated dome-like structure protecting all nozzle fittings against heat losses.

These and other objects of the invention will be apparent to persons skilled in the art from a study of the following description and accompanying drawing, in which Figure l is a longitudinal central sectional view taken through the nozzle and dome-like structure; 7

Fig. 2 is a'plan view of the domealike structure with parts thereof broken away to better disclose the interior construction, and

10 wardly from shown in Figure 1. This nozzle or opening terably fastened in place.

Fig. 3 is a diagrammatic view of the complete tank car having the improved construction.

Referring now to the drawing in detail, it will be seen that the tank A is supported upon trucks B of the customary type and that the tank has formed thereon a dome-like structure C. The tank itself is formed. as clearly shown in Figure 1, of a comparatively heavy shell 2 completely closed except for a nozzle 4, which projects upthe shell of the tank as clearly minates in laterally projecting flanges 6 drilled and tapped to receive stud bolts 8, by means of which a nozzle cover or lid in may be remov- This cover or lid is provided with a projecting rib l2 adapted to fit in a machined groove M formed in the nozzle flange, thus forming a tight joint and preventing any leakage of pressure from'the tank interior. The

lid or cover is drilled and tapped to receive into transport liquified gases in insulated strucduction and eduction pipes I6 and I8. respectively and above which are securely fastened inlet and outlet valves 20 and 22 respectively. The exterior connection to these valves is made through i 25 pipes 24 extending upwardly parallel to the valve stem in spaced relation thereto and terminating in a discharge connection normally capped by a plate or other means 26. In this manner a ready connection for charging or discharging the tank -0 may be made and any leakage past the valve seat becomes impossible when the cap is in place. The cover or lid also isprovided with any suitable number of openings 28 in which safety valves may be inserted. In the present instance there are three of these openings and three safety valves indicated at 30, 32 and 34 respectively. These valves are of substantially identical con-/ struction and are set to open at various pressures. For example, valve 30 may be set to open at 300 pounds per square inch, valve 32 at 340 pounds pressure and valve 34 at 3'i5 pounds pressure. In addition to these valves and as an added safety feature an approved safety vent 36 is provided and is of the type having a frangible disc designed to rupture at not more than 450 pounds pressure, thus positively protecting the tank shell against rupture. The form ofthe safety valves is immaterial but they are preferably of the type shown and which are fully disclosed in Willoughby Patent 1,774,690. In order to direct the escaping gases from the safety valves short vertically extending pipes 38 are provided secured to the valve structure and extending upwardly a sufficient distance as to direct mediate its length with an inner [with the other leg disposed inside with the lower edge supported by means of a top ring structure 62 of the escaping gases upwardly and away from the charging and discharging valves. In order to protect the various valve structures as comparatively heavy open ended cylinder 40 is provided, having its lower edge welded or otherwise secured to the nozzle lid or cover and removable therewith. This cylindrical protecting member is of sufficient height as to project slightly above the various valve structures. The entire tank shell 2 is covered by means of insulation 42 which, in the present case, com-" prises cork of inch thickness. This insulation is protected against entrance of moisture and destruction by means of a protecting steel housing 44 completely encasing the tank insulation except for a small area adjacent the nozzle. The opening in the outer shell adjacent the nozzle has attached thereto, as by spot welding or similar means, an angle shaped structure 46 having an upstanding flange 48 to which is in turn attached a second angular structure having one leg parallel to leg 48 and secured thereto, while the other leg 50 is directed outwardly substantially parallel to the protective casing of the tank, thus in efiect a ledge and upstanding flange is provided extending completely around the opening in the outer protective casing.

In order to fully insulate thetank nozzle cover or lid together with its valve structures, an inner cylindrical casing 52 is provided having attached thereto at its lower edge an angle form member 54 adapted to rest lightly on the tank insulation. This cylindrical inner casing is provided inter- 2 form ring 56 the casing and of the protective cylinder 40, with the web of the Z shaped ring resting upon the upper edge of the protective housing and supporting the protective inner casing 52. The inner casing forms a base around which cork or similar insulation 60 may be fitted angle struc tank. This protected by substantially inverted channel form attached to an outer casing 64, having its lower edge terminating inan outwardly directed flange 66 adapted to rest upon and be bolted as at 68 to the flange 50 of the tank protective structure, thus it will be seen that by removal of the bolts or other securing means 68 the. entire protective dome like structure may be lifted off of the tank without disturbing the insulation.

In order to close the upper end of the dome like insulating housing, a lid 10 is provided formed on a top plate 12, bottom plate 14 and ring like connected channel form side structure 16, thus inclosing a space which may be filled with insulation 78. As clearly shown, the top plate of the lid overlaps the upper member 62 of the housing and metallic contact between the lid and housing is broken by means of an insulating gasket 80 which also will prevent any leakage oi. air or gas from the housing. The lid may be directly removable or, as in the present case, it may behinged as at 82 to the dome like housing and secured in place by locking and sealing means 84. Since the insulated dome like structure is substantially air tight, it is necessary to vent the same and this is accomplished by means of a high level vent V formed by a pipe 86 extending through the lid and capped by means of a screen 88 and a metallic cap 90, all of which will prevent entrance of moisture or foreign having one leg rigidly secured to ture 54 and by the insulation of the insulation is completely housed and matter into the interior of the insulated dome like structure while permitting escape of gases liberated by the safety valves. It will be seen that the only direct metallic path for conducting heat from the tank structure to the outside air is established by cylindrical casing 40, ring 56 and the upper part of inner casing 52. This path, oi course, can be broken if desired by means of a gasket inserted between ring 56 and the upper edge of cylindrical housing 40 but the use of such a gasket is not deemed necessary since the entire cavity in which the valves are located will be at an extremely low temperature. Additional metallic paths formed by the vent pipe and by the sides of the lid are also established between the cavity to the dome like structure and the atmosphere but these paths are of small cross section and comparatively great length and can only transmit heat from the atmosphere to the cavity and not to the tank shell and the rate of transfer will be extremely slow since in many instances, such as with CO2 gas, the cavity may be considered as filled with a fairly good insulator. It has been found that six inches of cork, or equivalent insulation, is suflicient to economically insulate the dome like structure.

It is believed from the preceding description that the advantages of the construction will be apparent, but these advantages may be betten realized from a study of the following: A tank car constructed with ten inches of cork insulation and with the steel nozzle cover and valve fittings exposed when loaded with 60,000 pounds of carbon dioxide at 0.F. and with an outside temperature of will transmit through the cork 2148 B. t. u.s per hour and through the tank anchors 1260 B. t. u.s per hour, making a total through the cork and anchors of 3408 B. t. u.s per hour. The losses through the steel nozzle cover and valve fittings with a 20 inch diameter cover amounts to 30,485 B. t. u.s per hour, giving a total loss for the entire tank of 33,893 B. t. u.s with a hundred degree temperafrom developing an excessive pressure, its tem- I perature should not exceed 2 F. and to maintain this low temperature would require the escape of 282 pounds of liquid CO2 per hour and, further, this loss would begin in 3 hours and 40 minutes after the lading was placed in the tank at 0 F.

When, however, the nozzle and valve fittings are insulated as shown and described the total lossesthrough the insulated dome assembly are only 287 B. t. u.s per hour. In other words, a saving of over 30,000 B. t. u.s per hour has been made and the losses through the insulated dome like structure are only approximately one-ninth of the total loss of the tank which is now 3695 B. t. u.s per hour. To offset this loss and prevent temperature raise beyond 2 F. would require only 30 and 1 5 pounds of liquid C02 per with 60,000 pounds of liquid at 0 F. previously pointed out, the safety set to operate at 301 pounds pressure, which is the pressure at which liquefied CO2 at 2 F. must be retained.

By comparison it will be seen that a very great saving is accomplished through the proper insulation of the nozzle and valve fittings and that with the structure shown and described it will ing secured to and a dome-like lid, control. valves and in many cases be possible to transmit liquefied CO2 in the neighborhood of a without any loss of liquid gas whatsoever occurring, in other words, of the lading has risen 2 F. It will likewise be seen that there is approximately 30 hours difierence in time between a wholly insulated and a partially insulated tank beiore losses occur and these thirty hours would represent the loss of nearly two tons of liquid or, in other words, onefifteenth of the lading from the partially insulated tank.

While the invention or less in detail and has been described more with particular emphasis on the transportation of liquid CO2, it'will be obvious to persons skilled in the art that various modifications and rearrangements may be made and that the construction is equally applicable to transportation of liquids or gasesother than CO: and all. modifications and rearrangements of parts and as will fall within the scope of the appended claims which define my invention; a

What is claimed is: 1. In a railway c'ar tank for the low temperature transportation of liquid lading under pressure, a pressure retaining body, body insulation covering. the body, nozzle means carried by said body and projecting through said body insulation, a cover plate for said nozzle, control valves for the liquid lading carried by said cover plate, and an insulated dome-like structure completely covering said control valves and nozzleand substantially preventing heat losses therefrom, said dome-like structure being supported at least in part upon said cover plate by relatively thin metal means. t a

2. In a railway car tank for the low temperature transportation or liquid lading under pressure, a pressure retaining body, body insulation body, nozzle means carried by said body and projecting through said body insulation, protective means covering said insulation and terminating in spaced relation to said nozzle insulated dome-like structure secured to said protective means and completely housing said nozzle means to thereby substantially prevent heat losses therefrom, said dome like structure. being supported, at least upon the nozzle structure but free of connection thereto whereby movements of the protective housing will not be transmitted tothc nozzle structure.

3. In a railway car tank for the low temperature transportation of liquid lading under pres sure, a pressure retaining body having a nozzle projecting outwardly therefrom, body insulation coverin the entire body to a depth substantially equal to the nozzle projection, a lid secured to said nozzle; control valves for the liquid ladthe lid, protective means secured to said lid and extending upwardly therefrom, structure supported on said and completely housing-sald protective means, said fully insulated to :prevent loss of heat from the control valves and lid.

protective meansthousand miles before the temperature said nozzle, control valves uses of the structure are contemplated a vent heat loss 4. In a railway car tank for the low temperature transportation or liquid lading under pres sure, a pressure retaining body having a nozzle projecting outwardly covering the entire body to a depth substantially equal to the nozzle projection, a lid secured to for the liquid lading secured to the lid, protective casing secured to said lid and extending upwardly therefrom, and a dome-like structure supported on said protective casing and completely housing said lid, control valves and protective casing, said dome-like structure being fully insulated to prevent loss of heat from the control valves and lid, and said dome-like structure being formed with a hinged cover permitting access to the control valves.

5. In a railway car tank for the low temperature transportation of liquid lading under pressure, a pressure retaining body, body insulation covering the body, nozzle means carried by said body and projecting through said body insulation, and. a dome-like structure completely covering said nozzle means to substantially pre-' therefrom, said structure comprisin'gan inner casing supported on said nozzle structure in spaced relation thereto, insulation covering said inner casing, an outer casing connected to said inner casing and protecting said insulation, and a movable insulated lid carried by said casings. a

6. In a railway tank car including a body, I insulation covering said body, a nozzle carried by said body and extending through said insulation, a cover plate for sealing said nozzle, control valves carried by said cover plate, a protective casing enclosing said control valves and carried by said cover plate, an insulated covering enclosing said casing and spaced therefrom, said insulated covering being supported in direct contact with the insulation of said car body, and a closure forsaid insulated covering adapted in its closed position to overlie said protective casing in substantially axial alignment.

7. In a railway tank car including a tank body having an insulated covering, a nozzle extending from said body through said covering, a cover plate for said nozzle, control valves carried by said cover plate, a protective casing fixed to the marginal edge or said cover said .control valves, an insulated cover including a closure member enclosing said protective casing, said insulated cover forming a unit remov ably connected to the car body structure, and said closure member being adapted to immediately overlie said protective casing.

8. In a railway tank car ing an insulated for sealing said nozzle, control valves carried by said plate, a wall member fixed to the plate and extending about said control valves, and a domelike structure formed of relatively thick insulating material and including a removable tion arranged about said wall member and being detachably connected to the car therefrom, body insulation plate and enclosing including a body havcovering and a nozzle. a plate wall por-v 1 CLYDE H. FOL-MSBEE.

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