Patent Application
20090305179
The utility model relates to furnace systems in heavy-duty power-generating units, and can be used in the thermoelectric power industry.
Known in the art is a boiler furnace consisting of internal and external tubular screens that are designed as two concentrically mounted, equilateral prisms, wherein burners are set up on each face of the last of the screens tangentially to some conditional periphery (RU 909418, F23C 5/08, 1982).
In one known device for generating a vortical furnace flame for a specific type of fuel, the burners must be arranged in a specific manner relative to the screens. Since the burners are fixed in place in the known device, the latter is strictly “tied” to a specific type and even sort of fuel, which is one of its practical shortcomings.
Known in the art is a steam generator furnace (RU 953366, F23C 5/08, 1982) with a vertical annular combustion chamber consisting of external and internal tubular screens that are designed as concentrically mounted, equilateral prisms, wherein the lower portion of the screen face incorporates respective tangential burners and secondary air nozzles, with the latter being mounted in line with the burners.
Just as the analog described above, the known furnace is critical to the type of used fuel, which is one of its shortcomings.
A known technical solution involving nozzles arranged on the outer wall of the furnace involves the supply of all secondary air introduced into the furnace apart from the burners. This diminishes the heat absorption of the internal screen and, as a result, reduces furnace efficiency, which is a second of its shortcomings.
Feeding all secondary air into the lower portion of the furnace increases emissions of nitrogen oxides, which is also a shortcoming with respect to the known technical solution.
In addition, given the relatively high temperature of the exiting gases caused by the reduction in heat absorption of the screens, the furnace has large dimensions, and requires elevated capital expenditures for outfitting purposes.
The proposed utility model resolves the task of eliminating the aforementioned shortcomings using a specific furnace design.
According to the technical results obtained, various types of fuel can be optimally combusted, furnace efficiency can be increased, nitrogen oxide emissions can be cut, and furnace dimensions can be cut.
The technical results are achieved by virtue of the fact that burners are movably incorporated in the steam generator furnace with a vertical annular combustion chamber consisting of internal and external tubular screens that are designed as concentrically mounted, equilateral prisms, wherein the lower portion of their faces accommodates burners tangential to the conditional periphery, and secondary air nozzles, making it possible to regulate the diameter of the conditional periphery within a range of 0.4-0.7 D, where D is the diameter of a periphery entered in the cross section of the prism of the external screen, and the secondary air nozzles are mounted on two tiers over the height of the furnace.
The first tier of secondary air nozzles is located at the burner level on the faces of the external screen, while the second tier is situated in the upper portion of the furnace on the faces of the external and internal screens; the nozzles in the first tier are directed in line with the burners, while those in the second run counter to the burners.
The furnace contains a combustion chamber 1, external screen 2 and internal screen 3, secondary air nozzles 5 (first tier) and 6 (second tier).
The furnace operates as follows.
The fuel-air mixture passes through the burners 4 into chamber 1, where they undergo combustion. To provide optimal aerodynamics for the vortical furnace flame that ensure efficient fuel combustion while precluding any active influence of the flame on the screen, the burners are mounted tangentially to some conditional periphery, the diameter of which depends on the physicochemical properties of the fuel.
Movably mounting the burners makes it possible to regulate the diameter of the conditional periphery, and thereby optimize the combustion conditions for a specific sort of used fuel. In the proposed device, the range of regulation measures 0.4-0.7 D, where D is the diameter of a periphery entered in the cross section of the prism of the external screen, which ensures an efficient, optimal combustion of coal from practically all known coal deposits.
The secondary air nozzles 5 set up on the furnace faces at the burner level create a system of incremental horizontal secondary air supply, which provides the furnace with a symmetrical aerodynamic while eliminating individual grinders and lowering NOx emissions. To minimize the danger of slag formation on the external screens of the furnace and improve conditions for aeromixture combustion, the burners are set up in such a way that the aeromixture jet exits on the side of the flame, while the secondary air jet exits form the external screen.
The secondary air nozzles 6 set up in the upper portion of the furnace on the second tier ensure that the residual twists of exiting gases are extinguished, and consequently, that the heating surfaces in the gas duct are uniformly cleaned.
In addition, the counter-motion of the recycled air from nozzles 6 effectively lower the temperature of the exiting gases, which further lowers NOx emissions, and also enables a reduction in the number of gas ducts, and ultimately, furnace dimensions.
The table below presents comparative technical and economic indices for furnace assemblies based on the proposed furnace and a known furnace.
An analysis of data on the table shows that using the proposed furnace makes it possible to significantly reduce the weight and dimensional characteristics of the furnace, decrease its metal intensiveness and construction costs, which in the final analysis lowers the specific cost of energy produced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005119144 | Jun 2005 | RU | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/RU2005/000689 | 12/20/2005 | WO | 00 | 6/24/2009 |
