CA2659677A1

CA2659677A1 - Tank heater

Info

Publication number: CA2659677A1
Application number: CA2659677A
Authority: CA
Inventors: Peter R. Toth
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-03-26
Filing date: 2009-03-26
Publication date: 2010-09-26

Abstract

A heater for a pressurized tank is disclosed comprising: an enclosure having an open face bounded by a periphery that is shaped to conform to a surface of the pressurized tank; and a catalytic heater supported within the enclosure, the catalytic heater having a heat emitting surface directed towards the open face and, in operation, directed towards the pressurized tank. A method of heating the contents of a pressurized tank is also disclosed, the method comprising: heating a surface of a pressurized tank with a catalytic heater, the catalytic heater being supported within an enclosure that has an open face bounded by a periphery that is shaped to conform to the surface of the pressurized tank, a heat emitting surface of the catalytic heater being directed towards the open face of the enclosure and towards the pressurized tank. A catalytic heater having a heat emitting surface is also disclosed, in which the heat emitting surface of the catalytic heater is coloured with a highly heat radiative colour.

Description

TANK HEATER
TECHNICAL FIELD
[0001] This document relates to heaters, for example used to raise the vapour pressure in cylinders and tanks, particularly those that are pressurised and which may contain combustible materials.

BACKGROUND

[0002] In industry and life in general there is frequently found the necessity for heating the contents of a cylinder or tank that is located in a place subject to the ravages of the outdoors and the associated. A practical method to warm the contents is by utilising an electric heater strapped to the tank. There are a number of such systems available however if there is no electricity available another practical method is to shroud the tank or cylinder and pump warm air under the shroud thus heating the tank or cylinder.

[0003] The electrical systems in general include a heating element, a means by which to attach it to the tank and a power supply cable. The non-electrical systems in general include a tarp, a pump to circulate air and a means of heating the air such as gas burners or catalytic heaters.

[0004] There follows a list of problems associated with these types of systems when utilised for heating tanks or cylinders with pressurized liquid and gas contents.

[0005] Electric heaters require a power source which in many locations is not available.

[0006] In the case of a non-electrical system the entire tank is covered by a shroud and hot air is pumped underneath. The heated air warms the tank and the contents thus raising the tank vapour pressure. This is an inefficient way of transferring heat to the tank because air is an insulator. In addition a tremendous amount of fuel is wasted heating the entire tank when only a small amount of heat applied to the liquid portion of the contents of the tank would provide the same effect.

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SUMMARY

[0007] To address these problems, there is therefore provided in an embodiment a heater that will efficiently raise the vapour pressure within a tank by transferring heat to the liquid contents while utilizing the contents of the tank as the fuel source.

[0008] A heater for a pressurized tank is disclosed comprising: an enclosure having an open face bounded by a periphery that is shaped to conform to a surface of the pressurized tank; and a catalytic heater supported within the enclosure, the catalytic heater having a heat emitting surface directed towards the open face and, in operation, directed towards the pressurized tank.

[0009] A method of heating the contents of a pressurized tank is also disclosed, the method comprising: heating a surface of a pressurized tank with a catalytic heater, the catalytic heater being supported within an enclosure that has an open face bounded by a periphery that is shaped to conform to the surface of the pressurized tank, a heat emitting surface of the catalytic heater being directed towards the open face of the enclosure and towards the pressurized tank.

[0010] A catalytic heater having a heat emitting surface is also disclosed, in which the heat emitting surface of the catalytic heater is coloured with a highly heat radiative colour.

[0011] Further features and advantages will appear from the description that follows.
These and other aspects of the device and method are set out in the claims, which are incorporated here by reference.

BRIEF DESCRIPTION OF THE FIGURES

[0012] Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:

[0013] Figure 1 shows a cross section of a heater strapped to a tank.

[0014] Figure 2 shows an isometric view of the heater.

[0015] Figure 3 shows an isometric view of a cross section of the catalytic heater.

[0016] Figure 4 shows a flow diagram illustrating a method of heating the contents of a pressurized tank.

DESCRIPTION OF THE PREFERRED EMBODIMENT
[0009] Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.

[0017] Liquefied petroleum gas (LPG) is used as a fuel over a broad range of temperatures in many areas of the world ranging from the arctic to the tropics. LPG is stored in pressurised tanks in the form of liquid and gas. The liquid portion, being heavier, fills the lower portion of the tank cavity and the gas, being lighter, fills the upper portion of the tank cavity. When the need arises, gas or liquid is withdrawn from the tank and obeys the laws of chemical thermodynamics. As LPG is withdrawn the tank temperature drops and the pressure within the tank drops thus making it difficult to obtain sufficient quantities of LPG from the tank. Raising the temperature of the contents of the tank effectively increases the pressure within the tank and greater quantities of LPG may be withdrawn from the tank.

[0018] A heater that is in direct contact with a tank and in particular is located on the lower portion of the tank in the proximity of the liquid, transfers heat very efficiently to the contents of the tank. The liquid absorbs the heat and turns into vapour thus raising the tank pressure.

[0019] Ammonia is used as a fertilizer on farms and like LPG is also stored in pressurized tanks. The tanks are pulled behind tractors and ammonia is spread over fields by withdrawing liquid from the bottom of the tank. As ammonia is withdrawn the tank temperature drops and the pressure within the tank drops thus making it difficult to obtain sufficient quantities of ammonia from the tank. Because the tank is mobile there is no ready source of power and it is difficult to shroud.

[0020] Referring to Figure 1, a heater 10 for a pressurized tank, for example a cylindrical tank, is disclosed, heater 10 comprising an enclosure 16 having an open face 37 bounded by a periphery 39 that is shaped to conform to a surface 38 of the pressurized tank 12. Heater may be secured to the pressurized tank 12, for example by being strapped to propane tank 12 by suitable methods, for example with removable ratchet straps 14. Tank 12 may be a storage tank, for example located outdoors, for further example for commercial use.

[0021] A catalytic heater 18 is supported within the enclosure 16, the catalytic heater 18 having a heat emitting surface (for example output face 36 shown in Fig. 2) directed towards the open face 37 and, in operation, directed towards the pressurized tank 12.
Gas, for example gas 20 may be used as fuel for the catalytic heater 18 and is supplied from the propane tank 12 through piping 22. Pressure to the catalytic heater 18 may be regulated by a pressure regulator 24. The flow of gas 20 to the catalytic heater 18 may be regulated by a flow control valve 26. Pressure to the catalytic heater 18 may be displayed on pressure gauge 40.

[0022] Referring to Fig. 3, to start the heating process the catalytic membrane 28 must reach a preset temperature before catalytic combustion can occur. In some embodiments, gas 20 is configured to only flow once the combustion temperature is reached in order to prevent gas leakage. In some embodiments an electric heater 30 is used to preheat the catalytic membrane 28, although other suitable preheating techniques, such as the use of a gas burner (not shown), may be used. The source of electricity for this electric heater 30 may be from a suitable source such as a truck or car battery, and may be only briefly required to power the electric heater 30. Referring to Fig. 1, the internal electrical wiring 46 is connected to the external cable 48 inside junction box 50. Referring to Figs. 1 and 3, a thermocouple temperature sensor 32 may be used to detect the catalytic membrane 28 temperature and control when gas 20 may flow to the catalytic heater 18.

[0023] Referring to Fig. 3, gas 20 may flow into catalytic heater 18 through gas fitting 52 and be diffused internally through insulation 54. In some embodiments, when catalytic membrane 28 reaches a preset temperature level gas 20 flows to the catalytic heater 18 starting the catalytic combustion. If the temperature of the catalytic membrane 28 drops below a preset level gas flow may be shut off and the catalytic heater 18 restarted.
Referring to Fig. 2, a bulb temperature sensor 34 for example mounted within an interior of the enclosure, may be used to control the maximum temperature of the system by regulating gas flow to the catalytic heater 18.

[0024] Referring to Fig. 2, the catalytic heater 10 has a heat emitting surface, which when installed is directly heating the pressurized tank 12. The heat emitting surface, for example an output face 36, may be directed towards the propane tank 12.
Referring to Fig.
2, a catalytic heater 18 is illustrated, in which a heat-emitting surface, for example output face 36, is coloured with a highly heat radiative colour, for further example a dark color. In further embodiments, the heat emitting surface, for example output face 36 may be coloured black, for example if it is made of carbon fibre which is black rather than fibre-glass which is white. This increases the amount of radiant energy emitted from the catalytic heater 18.
In some embodiments, the surface of the pressurized tank, for example at least propane tank surface 38 adjacent enclosure 16 is at least one of painted and coated with a highly heat-absorbent colour such as a dark color, for example black, to increase the absorption of radiant energy from the catalytic heater 18.

[0025] The enclosure 16 may be shaped to fit with minimal clearance around a suitable portion of the surface area of the tank, for example surface 38, in order to minimize heat loss through the transition between the enclosure 16 and the tank 12. In some embodiments, the edges 44 of enclosure 16 that contact the tank 12 may be constructed of flexible material to provide a seal. By conforming to the surface 38, enclosure 16 is shaped to fit the contour of the surface 38, for example by being curved at the edges 44, for example to match at least one of specific tank curvature, size, and specific location on the tank itself. Referring to Fig.
1, the open end of enclosure 16 defines a conforming profile for the tank surface 38.
Insulation may be provided as part of the enclosure 16 for example around all sides of the heater 18 except the output face 36. In some embodiments the catalytic heater 18, for example output face 36, is shaped to conform to the surface 38 of the tank.

[0026] It should be understood that a variety of tank 12 shapes and sizes may be used.
Larger tanks have larger diameters and require more heating. Enclosures designed for larger tanks may have higher capacity heaters in them and may not be effectively used on smaller tanks as the curves do not match. Referring to Fig. 2, the enclosure 16 may have a combustion air inlet 40 at one location, for example a bottom, and an exhaust gas outlet 42 at a second location, for example at the top. Referring to Fig. 1, natural convection currents may be used to drive air up to the catalytic membrane 32 and over tank surface 38 providing fresh air for combustion and transferring additional heat from the exhaust gases to the propane tank 12.

[0027] In some embodiments, the fuel source for the catalytic heater 18 is contained within the tank 12 that is being heated. In these embodiments, the heater 18 may be connected to receive fuel as a fuel source of the heater 18 from the tank 12 to power the heater 18. An advantage of this is that no extra power source, for example electricity, is required to maintain the heater function. The heater may utilize the fuel within the tank to heat the tank and is thus may be a closed loop system requiring no external fuel supply. A
small amount of fuel may be utilized as the heat generated is applied directly to the liquid portion of the tank contents. The heater can be operated in low temperatures as catalytic heaters have very low input pressure requirements. In some embodiments, for example where the contents of tank 12 may not be used as fuel for the catalytic heater 18, the fuel source for heater 12 may be for example a separate tank of fuel, such as a propane cylinder.

[0028] In some embodiments, the heater 10 may be used to heat a pressurized tank of ammonia for use as fertilizer.

[0029] Referring to Fig. 4, a method of heating the contents of a pressurized tank is illustrated. Referring to Fig. 1, in a stage 100 (shown in Fig. 4), a surface, for example surface 38, of a pressurized tank, for example tank 12 is heated with a catalytic heater, for example heater 18, the catalytic heater being supported within an enclosure that has an open face bounded by a periphery that is shaped to conform to the surface of the pressurized tank, a heat emitting surface of the catalytic heater being directed towards the open face of the enclosure and towards the pressurized tank.. The enclosure 16 may be located at a lower portion, for example a bottom portion, of the tank 12, in order to ensure that heat applied to the surface 38 is more efficiently transferred to the liquid contents of the tank. In some embodiments, the method comprises coating the surface 38 of the tank with a highly heat-absorbent coating, for example a black-coloured coating such as black paint.
This increases the amount of heat from heater 18 that is absorbed by the tank. The heating stage 100 may be carried out while moving the tank 12, for example if the tank comprises ammonia, for further example being dispensed in a field as fertilizer as a vehicle connected to the tank 12 moves the tank 12.
[ 00 30 ] A person skilled in the art could make immaterial modifications to the heaters and, methods described and claimed in this patent disclosure without departing from the essence of the disclosure of this document. In the claims, the word "comprising" is used in its inclusive sense and does not exclude other elements being present. The indefinite article "a" before a claim feature does not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heater for a pressurized tank comprising:
an enclosure having an open face bounded by a periphery that is shaped to conform to a surface of the pressurized tank; and a catalytic heater supported within the enclosure, the catalytic heater having a heat emitting surface directed towards the open face and, in operation, directed towards the pressurized tank.

2. The heater of claim 1 connected to receive fuel as a fuel source of the catalytic heater from the pressurized tank.

3. The heater of any one of claim 1 - 2 in which the heat emitting surface of the catalytic heater is coloured with a highly heat radiative colour.

4. The heater of claim 3 in which the highly heat radiative colour is black.

5. The heater of any one of claim 1 - 3 in which the pressurized tank is cylindrical.

6. The heater of any one of claims 1-5 in which the heater is secured to the pressurized tank.

7. A catalytic heater having a heat emitting surface, in which the heat emitting surface of the catalytic heater is coloured with a highly heat radiative colour.

8. The catalytic heater of claim 7 in which the highly heat radiative colour is black.

9. A method of heating the contents of a pressurized tank, the method comprising:
heating a surface of a pressurized tank with a catalytic heater, the catalytic heater being supported within an enclosure that has an open face bounded by a periphery that is shaped to conform to the surface of the pressurized tank, a heat emitting surface of the catalytic heater being directed towards the open face of the enclosure and towards the pressurized tank.

10. The method of claim 9, in which the enclosure is located at a lower portion of the pressurized tank.

11. The method of anyone of claim 9 - 10 in which the pressurized tank contains fuel, and further comprising powering the catalytic heater with fuel from the pressurized tank.

12. The method of any one of claim 9 - 11 further comprising coating the surface of the pressurized tank with a highly heat absorbent coating.

13. The method of claim 12 in which the highly heat absorbent coating comprises a black coloured coating.

14. The method of any one of claim 9 - 13 in which heating is carried out while moving the pressurized tank.

15. The method of claim 14 in which the pressurized tank comprises ammonia.