Patent Application
20160298041
The subject matter disclosed herein relates to gasification systems and, more particularly, to a supply system for such gasification systems.
A gasification process involves the partial combustion of substance (e.g., carbonaceous fuel, such as biomass or coal) inside of a gasification reactor to generate “producer gas.” This gas may then be used in a variety of applications. The carbonaceous fuel used for generation of the producer gas is routed to the gasification reactor from a supply. The fuel is typically in a solid state and therefore requires a medium to facilitate the flow of the fuel along a supply line to the gasification reactor. The gas used to facilitate the flow may be referred to as a conveyance gas (e.g., N2 and/or CO2).
Although beneficial for routing the solid fuel to the gasification system, it is not advantageous to route the conveyance gas to the gasification reactor. Doing so increases the required volume of the gasification reactor to accommodate the additional volume of gas being routed therein. Alternatively, if the same size reactor is employed, the conveyance gas reduces the overall residence time of the reacting gas and fuel particles. Inclusion of the conveyance gas also increases the required size of equipment located downstream of the gasification reactor. Additionally for certain downstream chemical applications, the inert conveyance gas, such as N2, acts as an impurity and is desirably separated from the producer gas, but is not cost effective and will affect overall plant thermal efficiency.
According to one aspect of the invention, a fuel supply system for a gasification system is provided. The fuel supply system includes a gasifier. The fuel supply system also includes and a feed line for routing a substance and a conveyance fluid toward the gasifier. The supply system further includes a separation device located upstream of the gasifier and configured to receive the substance and the conveyance fluid from the feed line, the separation device separating the substance and the conveyance fluid, wherein only the substance is routed to the gasifier.
According to another aspect of the invention, a fuel supply system for a gasification system is provided. The fuel supply system includes a gasifier. The fuel supply system also includes a storage structure containing carbonaceous fuel in a solid state. The fuel supply system further includes a pump operatively coupled to the storage structure and configured to pump the carbonaceous fuel. The fuel supply system yet further includes a pump manifold containing a conveyance gas for mixing with the carbonaceous fuel. The fuel supply system also includes a feed line for routing a mixture of the carbonaceous fuel and the conveyance gas toward the gasifier. The fuel supply system further includes a cyclone separator located immediately upstream of the gasifier and coupled to the gasifier with a feed injector, the cyclone separator configured to receive the carbonaceous fuel and the conveyance gas from the feed line, the cyclone separator separating the carbonaceous fuel and the conveyance gas, wherein only the carbonaceous fuel is routed to the gasifier.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
The FIGURE is a schematic illustration of a fuel supply system for a gasification system.
The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
Referring to the Figure, a gasification system 10 is partially illustrated. A gasification system is configured to thermally convert a carbonaceous fuel into a more useful gaseous form of fuel (i.e., a fuel form that can be economically utilized with high energy recovery levels), referred to herein as “producer gas.” The gasification system 10 includes a gasifier 12, within which the thermal conversion of the carbonaceous fuel is carried out.
A supply system 14 is illustrated and is configured to store and route a substance to the gasifier 12 for reaction therein. The type of substance that is routed to the gasifier 12 by the supply system 14 may vary depending upon the particular application of use. For example, the fuel substance is a carbonaceous fuel, such as coal in some embodiments, and will be referred to herein as such, however, it is to be appreciated that other carbonaceous fuels, such as biomass may be employed with the embodiments of the supply system 14 described herein. Irrespective of the particular type of substance that is provided for gasification, the substance is typically in a solid state, such as in a particulate form (e.g., powder).
A substance storage structure 16 is provided to store the substance (e.g., carbonaceous fuel) in a ready state for routing to the gasifier 12. The substance storage structure 16 may be a fully or partially enclosed container configured to store the substance. A pump 18 is operatively coupled to the storage structure 16 and initiates routing of the substance from the substance storage structure 16 toward the gasifier 12.
A pump manifold 20 is operatively coupled to the pump 18 and may be configured to be operatively coupled to one or more other pumps and substance storage structures. The pump manifold 20 contains a conveyance fluid therein. The conveyance fluid is a medium employed to facilitate routing of the substance to the gasifier 12. This is beneficial due to the inertia of the solid state of the substance. While it is contemplated that the conveyance fluid is a liquid or two phase (i.e., liquid-gas) fluid, the conveyance fluid is typically a gas, such as nitrogen or carbon dioxide gas. The conveyance fluid may be stored in the pump manifold 20 at various pressures that may vary depending upon the particular application. In one example, the conveyance fluid is stored in the pump manifold 20 at a pressure of about 1000 psi. The substance and the conveyance fluid are mixed in the pump manifold 20 and routed along a feed line 22 toward the gasifier 12.
Upstream of the gasifier 12 is a separation device 24 that is configured to receive the mixture of the substance and the conveyance fluid from the feed line 22. The term “separation device” is used to generically define any assembly, device or system that separates a solid from a gas. In an exemplary embodiment, the separation device 24 is a cyclone separator that imparts a swirling of the mixture of substance and the conveyance fluid. The swirling is done a speed sufficient to force the solid particles (i.e., coal substance) toward and into contact with an inner wall 26 of the cyclone separator to cause the solid particles to fall toward a feed injector 28 of the gasifier 12 that facilitates a continuous flow of the solid particles into the gasifier 12. In the illustrated embodiment, the separation device 24 is located immediately upstream of the gasifier 12. Regardless of the precise positioning of the separation device 24, the gasifier 12 and the separation device 24 are operatively coupled in a manner that allows only the separated substance to enter the gasifier. In this manner, the gasifier remains free of the conveyance fluid that beneficially facilitates routing of the substance along the feed line 22, while avoiding the undesirable effects of routing the conveyance fluid into the gasifier 12.
The cyclone separator described above as the separation device 24 is merely one example of a solid-gas separation device. Various alternative separation devices may be employed as the separation device 24. For example, a settling chamber, a baffle chamber, a louver, an impingement plate separator, a gravity spray wet scrubber, centrifugal separator, a packed scrubber, a jet scrubber, an expander separator (e.g., Venturi tube), a filtering separator, and an electrostatic precipitator are all separation devices that may be employed to facilitate the desired level of solid-gas separation of the substance and the conveyance gas. The preceding list of separation devices is merely illustrative and it is not intended to be limiting, as other separation devices may be suitable for effective separation. It is to be appreciated that more than one separation device 24 may be employed to separate the substance and the conveyance gas. In the case of a plurality of separation devices, the devices may be arranged parallel to each other, in series with each other, or as an arrangement combining parallel and series.
As described above, the separation device 24 routes the solid coal substance to the gasifier 12 and retains the conveyance fluid. The conveyance fluid is then routed out of the separation device 24 via an outlet line 30 that is operatively coupled to the separation device 24. The outlet line 30 routes the conveyance fluid to a desired location. In an exemplary embodiment, the separated conveyance fluid is recycled back to the pump manifold 20 for further routing of substance. Additionally, the outlet line 30 routes a mixture of the substance and the conveyance fluid that has not been fully separated to a container or the like for further separation. Additionally, the high pressure conveyance gas from outlet line 30 may be utilized for power generation through its expansion, thus increasing the overall thermal efficiency of the system.
Advantageously, the separation device 24 separates the conveyance fluid from the solid substance just prior to feeding the solid substance to the gasifier 12. Avoiding the presence of the conveyance gas in the gasifier 12 increases the overall residence time and therefore thermal conversion of the substance to producer gas. Additionally, the size of the gasifier 12, as well as all downstream equipment, does not need to be increased to accommodate the conveyance fluid.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
