US3432097A - Railroad boxcar heater system - Google Patents

Description

March 11, 1969 s. F. HORSEY ET AL 3,432,097

RAILROAD BOXCAR HEATER SYSTEM Filed Oct. 28. 1966 Sheet of 2 f g /4 i l lNf/ENTORS s. F. HDRSEY w. J. L. TYLER fwd/1 06 fif R u March 11, 1969 s. F. HORSEY ET AL 3,432,097

RAILROAD BOXCAR HEATER SYSTEM Filed 001;. 28, 1966 Sheet 2 of 2 J6 & 000000 L 00C 0] O0 ocobbboicfiooo I #0 ro 900 oo'oo g I i 2/ E j I I I f 29 l I v 23 /6 32 T J T: 36 l I 30 y I 3 l I 2 .4 L I 24 33 3229 I be! 20 I INVENTORS S. F. HURRSEY W. J. L. TYLER ATTORNEYS,

United States Patent 0 4 us. (:1. 237-5 Int. Cl. B6011 1/22; B61d 27/00; F24d 3/00 6 Claims ABSTRACT OF THE DISCLOSURE A boxcar heater underslung below the car, the heater being fired by oil fuel and the gases of combustion being passed to a series of heating radiators within the boxcar, control means for bypassing the gases of combustion from the car heating radiators through a radiator external of the boxcar when the temperature within the boxcar exceeds a predetermined level. Means are also included to feed air directly to the combustion chamber of the heater and a spring loaded seismically balanced damper permits the passage of air from within the heater directly to the exhaust flue of the heater.

This invention relates to railroad boxcar heater systems in which the heater is slung under the boxcar and delivers controlled heat to the interior of the boxcar by means of a liquid medium.

In existing pot-type burners there is a serious limitation on their use due to the fact that they all have a limited throttling range and cannot be fired at lower than a basic firing rate without adverse effect to their operation. When such a heater is thermostatically controlled, and when the thermostat is demanding no heat from the furnace, serious overheating of the car occurs above the thermostat setting due to the inability of the system to throttle back to zero input. A further drawback to presently used pot-type burners is that on rapid acceleration of the boxcar, fuel oil is shunted out of the oil delivery pipe either into the furnace or back to the fuel metering valve with loss of continuity of oil flow with resulting inferior operation of the heater.

The heater system which is the subject of the present invention includes a radiator located outside the boxcar in parallel with the radiators mounted inside the car, with bypass valve means operated by the degree of heat of the exhaust gases from the burner whereby excess heat can be diverted from the radiators within the car to the radiator outside the car. It has been found that flue gas temperature is a sensitive and accurate indicator of firing rate and, for practical reasons is used to control the bypass valve setting.

The invention consists essentially of a firepot heater to which the flow of oil is controlled by means of a metering valve and suitable thermostat device. The metering valve is so mounted in relation to the firepot of the heater and with its oil pipe connection to the firepot positioned transversely of the car so that a constant flow of oil to the firepot is maintained during the periods of rapid accelerations which normally tend to empty the oil from the pipe connection. The air to the firepot is mainly delivered to the top portion of the firepot through an annular passage where the air is preheated, while the bottom of the firepot is insulated against very low temperatures. The heat from the firepot is directed into a heat transfer chamber located above the firepot Where the heat is transferred to a coil through which liquid ethylene glycol or other suitable medium is passed. Under normal operating conditions the heated liquid medium is circulated through a series of radiators located within the boxcar and is returned to the heating coil for reheating. A thermostat controls the heat delivered to the boxcar. However, when the thermostat causes the oil supply to be throttled back, excess heat sensed by a thermal actuator within the heater flue causes a bypass valve in the radiator pipe line to shut off the supply of heating medium to the radiators within the car and bypass it through a radiator located outside the car where the heat is rapidly drawn off and the system can then return to normal. In order to overcome the extremely high vacuum encountered in the exhaust gas flue when the car is traveling at high speed, a damper is fitted within the heater, rather than outside. This damper is actuated by flue vacuum and is restrained by a preloaded spring such that a rated draft pressure may be maintained in the firepot. The damper is seismically balanced so as to be unaffected by accelerations.

The object of the invention is to provide a boxcar heater by means of which overheating of the boxcar is prevented by bypassing excess heat in the heating system through an external radiator.

A further object of the invention is to provide a boxcar heater in which means are provided whereby a wide throttling range of the heater is obtained, as high as a 15:1 range.

A further object of the invention is to provide a flue gas thermal actuator whereby a bypass valve is actuated to bypass the car heating medium through an external radiator.

A further object of the invention is to provide means whereby the effect of high acceleration of the car on the supply of fuel to the heater is eliminated thereby maintaining a constant supply of fuel to the heater.

A further object of the invention is to provide a heater for boxcars which can be operated in any extreme of wind or temperature without inducing carbonization of any part of the heater or flue.

These and other objects of the invention will be apparent from the following detailed specification and the accompanying drawings, in which:

FIG. 1 is an outline diagram of the boxcar heating system according to the present invention.

FIG. 2 is a side elevation of the boxcar heater with the hinged door partially cut away and showing the combustion chamber partially in section.

FIG. 3 is a plan view of the heater with the top wall partially cut away to show the location of the carburetor and oil pipe line to the firepot.

FIG. 4 is a vertical sectional detail of the firepot.

FIG. 5 is a diagram showing the oil pipe connection to the firepot.

Referring to the drawings and particularly to FIG. 1, which is a diagram of the heater installation applied to a railroad boxcar, the 'boxcar 5 is indicated in chain dot lines and the car heater 6 is shown located externally of the car.

The heater 6 includes a heat transfer coil 7 from which a circulation of a heating medium such as liquid ethylene glycol or other suitable medium is passed through the pipe 8 to the series of radiators 9 located within the car The return flow of heating medium passes through the bypass valve 10 and thence to the coil 7 for recycling. The bypass valve 10 is controlled by a thermal actuator 11 located in the flue 12 from the heater 6. When the car temperature reaches the temperature setting of the car thermostat, the heater is caused to throttle back to low fire under the action of the thermostat. In consequence, the temperature of the gases in the flue 12 drops with the result that the actuator 11 causes the bypass valve to close off the flow of the heating medium through the car radiators 9 and to open by the bypass circuit through the pipe bypass radiator 13 located externally of the car 5. In this manner all excess heat generated in the heater 6 is dissipated externally of the car.

Referring now particularly to FIGS. 2 to 5 inclusive, the car heater includes an outer casing 14, with openings at the bottom, which is slung under the car 5 in well known manner. Mounted within the casing 14 is the heater proper consisting of a combustion chamber 15 Within which the heat transfer coil 7 is located, and a firepot 16 mounted below the combustion chamber by means of the fire ring 17.

The firepot 16 has a circular side wall 18 and a double bottom wall 1919a separated by a layer of insulation 20. The inner bottom wall 19 has a circular flange 21 engaging with the side wall 18 of the firepot while the outer bottom wall 19a has a circular flange 22 engaging with the circular flange 21, in the manner shown in FIG. 4. A central air tube 23 extends upwards from the bottom wall 19 and an annular ring 24 in the bottom wall 19a, concentric with the tube 23 permits air to pass upwards through the tube 23. The top end of the tube 23 is closed at 25. An annular chamber 26 located about the upper end of the tube 23 receives air from the tube 23 through the apertures 27 and the air is discharged from the chamber 26 into the combustion chamber 15 by means of the flared annular outlet 28.

A sleeve 29 is mounted in spaced relation about the air tube 23 and is provided with lower and upper dished baffles 30 and .31 respectively on which unburned fuel collects and is burned off.

The bottom wall 19a is held in engagement with the circular flange 22 of the bottom wall 19 by means of the pin 32, retaining bar 33 and pin 34.

The firepot 16 is surrounded in spaced relation by a circular sleeve 35 secured at its upper end to the fire ring 17. The lower end of the sleeve 35 extends slightly below the bottom wall 19a of the firepot. The sleeve 35 and the side wall 18 of the firepot form an annular air passage 36 by means of which atmospheric air passes up and enters the firepot 16 through the circular series of apertures 37.

Fuel oil is deliveed from a source supply through the pipe 38 to the metering valve 39 which is provided with a thermostat control 40 having the usual setting dial 41. The thermostat is connected with the interior of the car 5 by means of the leads or capillary tube 42.

A waste gas exhaust chamber 43, mounted on the side of the combustion chamber 15 is provided with a damper 44 pivoted on a vertical axis 45. The damper 44 is seismically balanced and preloaded by a spring 44a so as to be unaffected by accelerations and opercomes the extremity high flue vacuums when the car 5 is driven at high speed by permitting a bypass flow of air te enter the chamber 43 from the area within the casing 14. In the arrangement shown in FIGS. 4 and 5 the bypass valve actuator 11 is located in the chamber 43 where it is in contact with flue gases and senses the flue gas temperature and actuates the bypass valve 10 accordingly.

Referring more particularly to FIGS. '3 and 5 of the drawings, the longitudinal direction of the boxcar 5 is indicated by the double-ended arrow A. In order to eliminate the possibility of oil from the metering valve 39 to the firepot being ejected from the connecting pipe line either into the burner or into the metering valve 39,

the metering valve 39 is so positioned in relation to the firepot 16 that the oil pipe line 46 is as short as possible and is positioned at right angles to the arrow A so as to be free of longitudinal accelerations. The oil pipe line 46 is also so designed that the carburetor end of the oil column is vertical and the firepot end rises at an angle of at least 45 degrees to the horizontal. This results in a minimum emission of oil from lateral shock. Oil emission from the pipe 46 due to vertical car movements is prevented by the atmospheric pressure acting on the vertical oil column at each end of the pipe (see FIG. 5).

The casing 14 housing the heater installation is provided with an inspection door 47 giving access to the bypass valve 10 and metering valve 39.

From the above description it will be obvious that the invention departs from the conventional design of boxcar heaters, (a) instead of combustion air being introduced to the heater past a series of baffles below the firepot so that the air brushes the pot bottom and is preheated by it, the air is directed through the annular passage 36 and is preheated by the side wall 18 of the firepot, (b) instead of the firepot bottom being excessively cooled by the surrounding air, particularly in zero degree operation down to 50 F. where the pot bottom will only reach an operating temperature of 400-600 F. achieved in conventional operation, the pot bottom is insulated with the result that an operating temperature of 750800 F. can be reached resulting in a more efficient vapourization of fuel and reduction of carbon residue formation, the supply of fuel to the firepot is maintained regardless of longitudinal accelerations, whenever flue temperature rises a predetermined level the delivery of heat to the boxcar is cut off and bypassed through an external radiator thus maintaining a predetermined heat level in the boxcar and normal operation of the heater even at lowest throttling level.

What we claim is:

1. A railroad boxcar combustion heater system including a heater located under the boxcar, means to maintain a supply of fuel to the said heater, the said means including a metering valve and a thermostat for control of the metering valve responsive to the temperature Within the boxcar, and a fuel supply pipe between the said metering valve and the heater, the said fuel supply line being of short length and disposed transversely of the boxcar, a series of radiators located within the boxcar, means to circulate a heating medium from the heater through said boxcar radiators and back to said heater, a bypass radiator located externally of the boxcar, valve means including a thermal sensitive operator operable in response to variations in the temperature of the exhaust gases from the said heater, said valve means shutting off the circulation of the heating medium to the boxcar radiators and bypassing the heating medium through said external radiator when the temperature in the boxcar exceeds a predetermined value and restoring the heating medium to the boxcar radiators when the temperature of the boxcar drops to the predetermined level.

2. A heating system as set forth in claim 1 in which the said fuel supply pipe is disposed vertically at the ends thereof adjacent said metering valve and heater and the intermediate length of the pipe is disposed at an angle to the horizontal from its metering valve end towards the firepot.

3. A heating system as set forth in claim 1 in which the said heater includes a firepot and a combustion chamber located above the firepot, the said firepot having a circular side wall and an insulated bottom closure wall, and a circular wall concentric with and spaced outwardly of the circular wall of the firepot forms with the circular wall of the firepot an annular combustion air preheating passage, the said circular wall of the firepot having a series of apertures in the upper portion thereof permitting a flow of preheated combustion air from the said annular passage into the said firepot and combustion chamber.

4. A heating system as set forth in claim 3 in which the said firepot is provided 'With an axial air passage directing air from without the firepot directly into said combustion chamber.

5. A heating system as set forth in claim 1 in which the said heater is enclosed Within an outer casing with openings at the bottom and the said combustion chamber includes a gas exhaust chamber connected to a flue pipe, and a spring loaded seismically balanced damper pivoted about a vertical or horizontal axis on a wall of said gas exhaust chamber permits a flow of air from within said outer easing into the gas exhaust chamber.

6. A heating system as set forth in claim 1 in which the said heater includes an exhaust gas flue and the said valve means includes a thermal actuator located within the said exhaust gas flue and the valve means is operable on variation of the temperature of the exhaust gas in the said flue.

References Cited UNITED STATES PATENTS 2,181,742 11/1939 Rumpf 237-5 X 814,296 3/1906 Klausman 126-56 1,967,494 7/ 1934 Brede 236-45 2,215,510 9/1940 Jones et al 126-56 2,259,845 10/ 1941 Valjean 236-45 2,302,678 11/1942 Crew 236-45 2,393,868 1/19'46 Niven 237-5 2,973,186 2/1961 Hazard 2 37-5 X EDWARD J. MICHAEL, Primary Examiner.

US. Cl. X.R. 237-36

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