Patent Application
20120012036
This application does not claim the benefit of any pending patent application.
This application is not referenced in any microfiche appendix.
The present invention is generally directed toward an apparatus to create steam. More specifically, the present invention is directed toward a once through steam generator.
The prior art has many different types of steam generating systems and apparatus. These prior art systems and apparatus, however, are not the most efficient or effective. Additionally, these systems have a significant amount of solids deposition on the inner surfaced of the steam generator tubes. Additionally, the cost to erect these apparatus is typically very expensive. Accordingly, there is a need for an improved steam generator.
The present invention is generally directed toward a once-through steam generator (OTSG).
One aspect of the present invention discloses once-through steam generator having a steam generation apparatus in communication with a combustion apparatus and a combustion air input/output apparatus. Combustion air enters the OTSG through the air input/output apparatus and is then fed into a combustion apparatus to generate flue gas. The flue gas is then fed into the steam generation apparatus to generate steam. The flue gas is returned to the air input/output apparatus by way of a flue gas recirculation (FGR) stream where it can either be released from the system or mixed with new combustion air and recycled back through the combustion system. The steam that is created is then used with the recovery of oil from a reservoir.
One aspect of the combustion system portion of the present invention discloses a combustion air fan, a burner and a combustion chamber. The combustion air fan pulls combustion air through the air input/output apparatus through the burner and into the combustion chamber. When the combustion air passes through burner it is mixed with fuel to create a fuel/air mixture. This mixture combusts when it is inside the combustion chamber producing flue gas.
One aspect of the steam generator system portion of the present invention provides for the creation of steam through a once-through steam generation (OTSG) process. A series of tubes are arranged in a coiled configuration. Feedwater in introduced into the tubes through an inlet. Once the water has been converted into steam, the steam exits the tubes through an outlet. Flue gas is introduced into the steam generator system and passed over the tubes. Due to the temperature differential between the temperature of the feedwater and flue gas, the feedwater is converted into steam. The flue gas then exits the steam generator system portion through a flue gas recirculation stream where it is returned to the air input/output apparatus.
One aspect of the air input/output portion of the present invention provides for the in-flow of combustion air and an out-flow of flue gas. Combustion air enters the air input/output portion through an inlet/outlet opening and passes through an air control damper in to a combustion air duct. Once the combustion air passes into the combustion air duct, it is then introduced into the combustion portion of the present invention where it is converted into flue gas. Once the flue gas has heated the feedwater and has exited the steam generator system portion of the present invention, it passes through a flue gas recirculation damper and back into the input/output portion of the present invention allowing the flue gas to be recycled back into the combustion system.
Upon reading the included description, various alternative embodiments will become obvious to those skilled in the art. These embodiments are to be considered within the scope and spirit of the subject invention, which is only limited by the claims which follow and their equivalents.
The following detailed description shows the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made for the purpose of illustrating the general principles of the invention and the best mode for practicing the invention, since the scope of the invention is best defined by the appended claims. The invention is capable of other embodiments and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein are for the purpose of description and not of limitation.
Referring now to
Having broadly discussed the overall process, numerous advantages attributable to the process are evinced. These include i) improved combustion efficiency due to the preheating of combustion air with the heat of recirculated flue gas that would normally go out the stack; ii) improved oil recovery from a reservoir through increased reliability of the steam generator; iii) enhanced steam generation due to a reduction in dissolved solids deposition on the inner surfaces of the steam generator tubes; iv) lower stack emissions of NOx and v) improved erection cost and vi) improved shipping costs due to a more compact combustion system or vii) any combination of these features.
Referring now to
The fuel, contained in any of air or oxygen mixture, may be selected from any suitable hydrocarbon fuel, non limiting examples of which include natural gas, bitumen, fuel oil, heavy oil, residuum, emulsified fuel, asphaltenes, petcoke, coal, and combinations thereof.
Referring now to
In this embodiment, tubes 46 are placed in a combination counter-current 48/co-current 50 configuration. This configuration provides for the minimization of the creation of solid deposits in the tubes. The tubes 52 which are part of the counter-current section 48 are cooler in temperature and make better use of the temperature difference between the flue gas 28 and the feedwater 42. The evaporation of feedwater 42 into steam 44 occurs in tubes 54 which are part of the co-current section 50. By having all the evaporation in the tubes 54 that are part of the co-current section 50, the water-steam is in placed in an up-flow which encourages proper flow through the tubes 46 and helps relieve steam bubbles that have formed within feedwater 42.
Referring now to
The combustion air duct 18 is in communication with the combustion system 20. Due to the negative pressure within the combustion air duct 18 created by the combustion fan 22, combustion air 12 enters the air input/output apparatus 13 through the inlet/outlet 14 and passes through the air control damper 16 and the combustion air duct 18 into the combustion system 20.
Once the combustion air 12 passes through the combustion system 20 and is converted into flue gas 28, the flue gas 28 passed through steam generator system 40 and enters into air input/output apparatus 13 and passes through the FGR damper 56. Depending on the heat needs of the combustion system 20, flue gas 28 is either recycled back through the system or released from the system. The amount of combustion air 12 and flue gas 28 that is introduced into the combustion system 20 can be controlled by the opening and closing of air control damper 16 and FGR control damper 56.
When the heat needs require less heat to the combustion system 20, FGR control damper 56 closes allowing flue gas 28 to escape through the air inlet/outlet 14. When the heat needs require more heat, the FGR control damper 56 opens to allow flue gas 28 to be drawn into the combustion air duct 18 via the negative pressure created by the combustion fan 22. When the flue gas 28 enters the combustion air duct 18, it mixes with combustion air 12 being drawn into the system through air inlet/outlet 14. Due to the heat of the flue gas 28, combustion air 12 is preheated prior to its entry into the combustion system 20. This preheating allows for more combustion efficiency.
By controlling the amount of combustion air 12 and flue gas 28 that is introduced into the combustion system 20, the amount of heat within the steam generator system 40 can be controlled. This in turn allows for the control of the amount of heat that is used for the creation of steam 44, which allows for a control of the amount of solid deposits within the inside of tubes 46 that is created during the evaporation process.
While embodiments of the present invention have been illustrated and described, such disclosures should not be regarded as any limitation of the scope of our invention. The true scope of our invention is defined in the appended claims. Therefore, it is intended that the appended claims shall be construed to include both the preferred embodiment and all such variations and modifications as fall within the spirit and scope of the invention.
