Patent Application
20060105283
1. Field of the Invention
The present invention generally pertains to a pipeline heating apparatus and methods of heating gas and liquid streams using the same. The inventive pipeline heaters employ flameless, catalytic IR emitters positioned about a section of pipe which is in the form of a volume bottle for increasing the residence time of the fluid in the heater.
2. Description of the Prior Art
Pipeline heaters are used to heat gas and liquids flowing through a pipeline in order to prevent regulators and various sensing equipment from freezing up during pipeline operation. Traditionally, water bath indirect heaters have been used for this purpose. In water bath heaters, a vessel is filed with water or a mixture of water and ethylene glycol. A fire tube and process coil are submerged in the bath which transfers heat from the fire tube to the process stream in the coil. These types of heaters have the drawback in that the fire tubes produce significant amounts of noise and ethylene glycol presents health risks to people, pets, and property. In addition, water bath heaters tend to be less efficient because the heat transfer occurs through an intermediate medium, namely the water bath.
Because of the undesirable attributes of conventional water bath heaters, there is a true need for quiet and efficient apparatus and methods for heating pipeline fluids such as natural gas and other hydrocarbon streams. Furthermore, there is a particular need for an environmentally friendly pipeline heater system that generates virtually no nitrous oxide or volatile organic compounds.
The present invention generally pertains to a pipeline heater and a method of heating a fluid stream therewith. As used herein, the term “fluid” refers to compositions in either a liquid or gaseous state. The inventive pipeline heater generally comprises an inlet manifold presenting a diameter D1, a pipe section presenting a diameter D2, a plurality of flameless catalytic IR emitters positioned about the pipe section in a substantially diamond-shaped configuration, and an outlet manifold presenting a diameter D3. As used herein, the term “substantially diamond-shaped configuration” refers to the cross-sectional configuration of the catalytic emitter array taken along the plane that perpendicularly intersects the direction of fluid flow in the pipe. In preferred embodiments, the emitters are arranged at an approximately 90° incline relative to the emitters adjacent thereto and are in a surrounding relationship to the pipe carrying the fluid to be heated. It has been discovered that by positioning the catalytic emitters in such a manner that the quantity of heat transferred to the pipe (and ultimately to the fluid) can be significantly increased. Consequently, this arrangement is capable of heating the fluid stream to a temperature that is at least about 100° F. greater than a similarly sized, conventional heater.
In another aspect, the inventive pipeline heater comprises an inlet manifold presenting a diameter D1, a pipe section presenting a diameter D2, a plurality of flameless catalytic IR emitters positioned about the pipe section, and an outlet manifold presenting a diameter D3, with D2 being greater than each of D1 and D3. Unless otherwise specified, the term “diameter” as used herein in relation to the manifolds and pipe section refer to the inner diameter of the structures through which the fluid stream flows. Preferably, D2 is at least 50% greater, more preferably at least about 100% greater, even more preferably at least about 200% greater, and most preferably at least about 400% greater than each of D1 and D3. In this manner, the pipe section forms a “volume bottle” which serves to slow the fluid flow rate through the heater thereby increasing the residence time of the fluid in the heater and allowing for greater heat transfer to occur. For example, in the instance where D1 is about 2 inches, D2 can be up to about 8 inches, or when D, is about 4 inches, D2 can be about 10 inches.
The pipes section used to conduct the pipeline fluid through the heater can be a relatively straight section thereby making a single pass through the heater, or the pipe section can be serpentine thereby making multiple passes through the heater. In the case of multiple passes, each pass has a plurality of flameless catalytic IR emitters positioned thereabout, and preferably in a substantially diamond-shaped configuration. Because the catalytic emitters do not produce a flame, the heaters operate much more quietly than conventional water bath-type heaters and can be safely used in virtually any location. Also, the use of automation equipment allows for remote operation of the heater.
Pipeline heaters according to the present invention are generally environmentally safe and nuisance free. The pipeline heaters produce virtually no nitrous oxide or volatile organic compounds during operation thereof. Because there are no fluids, stacks, or containment rings, the pipeline heaters present few rust corrosion issues and present no chemical odor problems.
Methods of using the inventive heaters are also provided herewith and generally comprise providing a heater such as those described above and passing a fluid stream therethrough for heating of the stream.
The following examples set forth preferred pipeline heaters in accordance with the present invention. It is to be understood, however, that these examples are provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention.
Turning now to the drawings, and in particular
The diamond-shaped emitter arrangement allows more of the infrared energy to be concentrated over the entire circumference of the serpentine pipe 12. This arrangement provides substantially increased pipe temperatures and improves efficiency by directing more of the infrared energy toward pipe 12.
In operation, the fluid to be heated enters heater 10 through inlet 18. Heater 10 can be placed directly in-line with the pipeline system and is coupled thereto by flanges 20. The fluid flows through an inlet manifold 22 to which a sensing and regulating equipment 24 that monitor various properties of the inlet fluid may be attached. In the embodiment shown in
After the last pass of pipe 12, the heated fluid flows through exit manifold 26 and is returned to the pipeline system at outlet 28. The diameter of exit manifold 26 is also less than the diameter of pipe 12, and preferably is approximately the same as inlet manifold 22. Manifold 26 also is provided with a number of ports 30 to which sensing equipment capable of monitoring properties of the heated fluid stream can be attached.
A venting hood 31 is provided proximate the top portion of housing 14 thereby permitting the escape of exhaust gases from catalytic emitters 16. The top portion of housing 14 comprises a pair of upwardly converging sidewall sections 29 which direct the exhaust gases toward hood 31. Side panels (not shown) can be placed around the outer periphery of housing 14 to further insulate heater 10. Slats may be provided in the side panels to provide additional ventilation.
Heater 10 is capable of being made fully automated thereby allowing for remote start, stop, and temperature control. For example, the operation of heater 10 can be automatically adjusted to achieve a desired fluid exit temperature by sensing the input temperature of the fluid in manifold 22 and controlling the output of emitters 16. This automatic operation allows heater 10 to be placed in locations that are removed from populated areas without requiring an on-site human presence. Monitoring of the heater performance can occur at a more centralized and convenient location.
Heater 10 can be modified to operate without a conventional electrical energy source. This modification is particularly useful in remote locations or in locations that are prone to power interruptions. During start up of the heater, a portable generator is used to preheat the catalyst. Operation of the heater is spontaneous from that point forward. A thermostat is then used to control the operating temperature by adjusting the fuel-gas flow rate between a preset minimum and maximum.
Turning now to
Preferably, pipe 12 has a dark finish in order to facilitate the maximum absorption of infrared energy from emitters 16. Conversely, housing 14 and many of the other components comprising heater 10 comprise a lighter, reflective finish in order to retain as much infrared energy within heater 10 as possible. Insulation may also be added to heater 10 to assist in this goal and increase the overall efficiency of heater 10. Preferably, housing 14, in large part, is made from stainless steel.
The inventive heaters 10 can be used in many different applications where cold operating conditions exist. The heaters are particularly useful in heating natural gas streams, but may also be used to heat high pressure gas from wellheads and distribution stations, natural gas at gate stations, and high pressure gas from oil fields. The heaters can also be used to heat liquid streams such as light hydrocarbons, viscous oils, and water or various aqueous streams in order to reduce pump pressures and improve pumping efficiencies.
