US1962262A - Tubular heater - Google Patents

Description

June 12, 1934.

N. W. THOMPSON TUBULAR HEATER Filed Nov. 10, 1951 Invenjo r: Nelson W. Thom By his Attqrngy Patented June 12, 1934 PATENT OFFICE TUBULAR HEATER Nelson Wamsley Thompson, Oakland, Calif., as-

signor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application November 10, 1931, Serial No. 574,234

9 Claims. (01. 122-356) My invention relates to the tubular heaters having a radiant heat zone vand a convection zone and although'not limited thereto is more particularly intended for tubular heaters used for heating or cracking of hydrocarbon oils.

One object of my invention is to provide efficient and economical means for applying intense heat under easy control to hydrocarbon oils for the purpose of altering their physical and/or chemical character, while preventing the combustion gases, on their path to the convection zone from dangerously approaching and overheating the bank of tubes in the radiant heat zone.

Another object of my invention is to provide 5 the heater with simple arched crosswalls in the radiant heat zone to support the tubes and to strengthen the long walls of the heater.

This invention accordingly consists in the features of construction and the arrangement and 29 design of the parts, which will be more fully indicated in the following description and claims.

In order to disclose more completely this in- .vention reference is had to the accompanying drawing showing in Fig. 1 a sectional view of my tubular heater. 1 In the drawing, 1 is the front wall of the heater; 2 is a crossarch; an air preheater 3, having a vertical partition 4, is built in in the furnace; air is admitted in front through an opening 5 and passed back and forth through the preheater and via the metal enclosure 6 to the burner 'l. The combustion gases are conducted horizontally through the radiant heat zone 8, towards the back wall 9 of the furnace, where the downdraft causes them to pass between the air-preheater 3 and the backwall 9 away from the radiant heat tubes. The combustion gases then pass through the arch 10 into the convection zone 11, where they come in direct contact with the bank of tubes 12, and from where they flow into the flue 13 and to the stack 14. The radiant heat tubes 15 are supported at their ends by the side walls of the heater of which the drawing shows the one sidewall 16 in the background. The radiant tubes 15 are further supported at one or more intermediate points by rollers 1'1 positioned upon the crossarches 2, which crossarches at the same time brace the front and rear wall of the heater.

Buckstays 18 connected at the top by cross beams 19 prevent the front and rear walls from bulging. The radiant heat tubes are covered at the top by a roof of tile 20 suspended from the cross beams 19.

One of the advantages of my invention resides in protecting the radiant tubes from being-impinged by flame, locally overheated and bumed out with disastrous consequences. The radiant tubes are at a safe distance from the combustion gases at 8, which are led horizontally across the furnace, and further in a downward direction to the convection zone away from ,the radiant tubes.

Another advantage resides in the method of supporting the radiant tubes at. intermediate points between the ends by crossarches. This eliminates the difficult, expensive, and unsatisfactory method of suspending these tubes from the roof or of supporting them by special expensive heat resistant beams across the furnace. It further allows the use of long tubes in the radiant zone, keeping the span between two supporting points well within the limits of safety. The use of extra long tubes decreases the number of return bends which in turn decreases the pressure loss through the coil, which results in a more economical operation. Furthermore, by supporting the bank of tubes on rollers positioned in troughs placed on top of the supporting crossarches the whole bank of radiant heat tubes is made of the full-floating type and is able to freely expand lengthwise. This will prevent the buildso ing up of stresses across the supporting walls in the axial direction of the tubes, which might be disastrous. Asecond function of the crossarches is the reinforcement obtained for the front and back walls, by balancing the action of the buck- 5 stays, which will prevent the walls from caving in and bulging with the unavoidable consequence of weakening and leakage due to formation of cracks.

I claim as my invention:

1. Fluid heating apparatus comprising: in combination, a horizontal radiation combustion zone, means for effecting combustion within said zone, a downward gas passage from the radiation zone to a convection zone for deflecting combustion gases from the top of the radiation zone, an air conduit interposed between said zones and delivering air directly to the burners, said radiation zone being positioned directly above the convection zone, a multiplicity of tubular elements within said zones providing flow paths for the fluid to be heated, a number of said elements being positioned within the radiation zone off the general direction of flow of the burning gases, the other portion of said elements being placed in the convection zone and in the path of the combustion gases.

2. Fluid heating apparatus comprising: incombination, a radiation combustion zone, means for effecting combustion within said zone, a downward gas passage from the radiation zone to a convection zone for deflecting combustion gases from the top of the radiation zone, an air conduit interposed between said zones and delivering air to the burners, said radiation zone being positioned directly above the convection zone, a multiplicity of tubular elements within said zones providing flow paths for the fluid to be heated, a number of said elements being positioned within the radiation zone off the general direction of flow of the burning gases, and freely supported by arched cross-walls substantially not obstructing said flow and which reinforces two walls of the apparatus, the other portion of said elements being placed in the convection zone and in the path of the combustion gases.

3. Fluid heating apparatus comprising: in combination, a radiation combustion zone, means for effecting combustion within said zone, a downward gas passage from the radiation zone to a convection zone for deflecting combustion gases from the top of the radiation zone, an air conduit interposed between said zones and delivering air to the burners, a multiplicity of tubular elements within said zones providing flow paths for the fluid to be heated, a number of said elements being positioned within the radiation zone off the general direction of flow of the burning gases and resting upon roller-like members, supported by arched cross-walls substantially not obstructing said flow, the other portion of said elements being placed in the convection zone and in the path of the combustion gases.

4. Fluid heating apparatus comprising: in combination, a horizontal radiation combustion zone and separated therefrom a convection heating zone positioned directly below said radiation zone, an air conduit interposed between said zones, a downward gas passage from the radiation zone to the convection zone for deflecting combustion gases from the top of the radiation zone, a means for eifecting combustion within the radiation zone, a series of heating tubes within the radiation zone disposed substantially without the path of the combustion gases and another series of heating tubes within the convection zone.

5. Fluid heating apparatus comprising: in combination, a horizontal radiation combustion zone and a horizontal convection heating zone positioned directly below said radiation zone, an air conduit interposed between said zones, a downward gas passage from the radiation zone to the convection zone for deflecting combustion gases from the top of the radiation zone, a means for effecting combustion within the radiation zone, a series of heating tubes within the radiation zone disposed substantially without the path of the combustion gases and another series of heating tubes within the convection zone.

6. Fluid heating apparatus comprising: in combination, a radiation combustion zone, a convection zone and a gas passage from the radiation zone to said convection zone, said radiation zone being positioned directly above said convection zone, an air conduit interposed between said zones, a series of heating tubes in said zones and one or more arched cross-walls in the radiation zone for freely supporting the tubes while reinforcing two walls of the apparatus.

7. Fluid heating apparatus comprising: in combination, a radiation combustion zone having a series of heating tubes arranged along one side thereof, a burner, acombustion gas exit passage at the side of the zone opposite to the tubes and away from the burner, allowing to divert the combustion gases away from the tubes and to direct them to a convection zone positioned directly below said radiation zone and an air conduit interposed between said zones.

8. In a furnace provided with heating tubes and a cross-wall, a tube-supporting means which comprise rollers supported by the cross-wall in direct supporting contact with the tubes, said cross-wall reinforcing two walls of the furnace.

9. Fluid heating apparatus comprising in combination, a radiation combustion zone, aconvection zone and a gas passage from the radiation zone to said convection zone, said radiation zone being positioned directly above the convection zone, an air conduit interposed between said zones, a series of heating tubes in said zones and one or more arched cross-walls in the radiation zone for supporting side walls of the apparatus and provided with rollers for slidably supporting tubes within the radiation zone.

NELSON WAMSLEY THOMPSON.

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