Patent Application
20140261128
1. Field of the Invention
This invention is related generally to power plants and more particularly to a system and method for mounting an industrial gas turbine or generator on a vessel.
2. Description of Related Art
Large structures such as industrial gas turbines are conventionally positioned on land. The mounting of such large structures on marine vessels has previously believed to have been impossible.
A principle object of the present invention is to provide a new system and method for barge mounting an industrial gas turbine or generator, thereby overcoming previously known limitations. Embodiments of the present invention achieve these and other objectives provided herein below.
According to an embodiment of the present invention, a vessel includes a hull structure, a foundation, a plurality of springs, and plurality of hydraulic jacks. The hull structure is configured to float on water. The foundation is mounted on top of the hull structure and has significant mass. The foundation is configured to support a turbine structure and to absorb at least a portion of the forces or kinetic energy from the turbine structure. The plurality of springs are positioned between the hull structure and the foundation. The plurality of springs are configured to isolate the foundation from the effects of deflections in the hull structure, to absorb at least a portion of the forces or kinetic energy transferred from the turbine structure, and to transfer at least another portion of the forces or kinetic energy from the turbine structure to the hull structure. A plurality of hydraulic jacks are positioned between the hull structure and the foundation and are configured to adjust the degree of stiffness between the hull structure and the foundation, and to absorb forces or kinetic energy from the turbine structure.
Certain embodiments of the present invention may have a number of technical advantages. For example, some embodiments may allow the mounting of an industrial gas turbine on a vessel. Some other embodiments may absorb forces through one or more of hydraulic jacks, isolation springs, and a cement foundation. Some other embodiments may adjust a degree of stiffness between a cement foundation and hull structure of the vessel. Various embodiments may include some, all, or none of the above advantages. Particular embodiments may include other advantages.
Before undertaking the DESCRIPTION OF EXAMPLE EMBODIMENTS below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.
For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts:
This disclosure relates to the mounting of large industrial gas turbines on floating barges or other floating marine vessels for the supply of large capacity electrical energy to centers of population under emergency conditions or long term use. Conventionally, large industrial gas turbines have not been installed or mounted on barges due to a variety of concerns with such mounting. Among the concerns with the mounting of such large structures on barges include concerns over dead loads and live loads. As one example live load concern, vibration amplitudes during run up and at operating speeds need to be significantly limited. This is because vibration sensors associated with the gas turbine will automatically shut down the gas turbine if design amplitudes are exceeded. As one example dead load concern, the sheer weight of the turbines and potential deflections in the structure from environmental conditions could prohibitively prevent a foundation from adequately supporting the turbine—again resulting in a shut down of the turbine from sensor detection of anomalies in operation.
Given such concerns, teachings of certain embodiments of the disclosure recognize a floating structure capable of supporting large structures through features that mitigate dead load and live load concerns. In certain embodiments, such structures (e.g., industrial gas turbines) will not know whether they are on land or on a floating structure.
The mounting system 100 includes a foundation 110, a hull structure 120, and springs 130. The hull structure 120 is generally shown floating in water 84 having a water line 80 that separates water 84 from air 82. Each of the foundation 110, the hull structure 120, and the springs 130 absorb and/or transfer energy that is imparted thereon—whether it be vibrations from the gas turbine 210 and associated generator 220 or from deflections that may occur in the hull structure 120. Each will be described in more detail below.
Among the items that may be considered in the design of a floating gas turbine power generation facility are the following: the barge, the barge's steel structures, and the fact that the barge is floating in water. The effects of buoyancy and the distribution of weight of the barge (including the gas turbine generator that may be loaded thereon) can create bending moments, bending stresses, and shear stresses in the hull girder or hull structure. These stresses, in turn, can cause the girder to bend either in a sagging or hogging mode. The degree of deflection of the hull girder is the product of the bending moment and the stiffness of the hull structure. The greater the stiffness of the hull structure, the lower the amplitudes of deflection.
Given such design concerns, the hull structures (e.g., hull structure 120) of a floating power plant may be designed to reduce the amplitudes of deflection to a minimum while providing a stiff supporting structure for the foundation (e.g., foundation 110) supporting the turbine and generator. However, even considering the stiffness of the hull structure and the distribution of weight and ballast along the hull structure to reduce bending moments, other external factors may also act upon the hull structure. One such factor is the thermal differential between the temperature of water 84 and the temperature of the ambient air 82. The difference between the two may create thermal stresses in the hull, which, in turn, may create vertical deflections, sag, or both. Additionally, in particular configurations, the sun may create thermal stresses that cause both vertical and horizontal deflections of the hull girder of amplitude. This may be dependent upon the strength of the sun's rays and their angle, which may constantly change.
With reference to
Additionally, the springs 130 in certain configurations may also help uncouple the static and dynamic behavior of the gas turbine 210/generator 220. That is, vibration forces from the gas turbine 210/generator 220 may be at least partially absorbed by the springs 130. For those forces that are not absorbed by the springs 130, the springs 130 may act as a conduit to translate a portion of the forces to the hull structure 120. The hull structure 120, in turn, may be made of materials that dampen and/or translate forces.
Although springs 130 are shown in this embodiment, other types of energy absorption and transfer structures may be utilized in other embodiments. For example, there are a variety of energy absorbing materials available on the market that are designed to absorb vibrations.
To support the heavy static loads of the gas turbine 210 and generator 220 and the even greater loads and forces created by the gas turbine 210 and generator 220 when in operation, the foundation 110 may be designed such that it has significant mass. This significant mass, itself, helps dampen vibrations from one or both of the gas turbine 210 and generator 220. In particular configurations, the foundation 110 (or plinth) may be constructed of reinforced steel and concrete. In certain configurations, the mass of the foundation 110 may be 1700 metric tons. In other configurations, the mass of the foundation 110 may be more than or less than 1700 metric tons. In certain configurations, the foundation 110 may have a particular shape and be made of varying materials. For example, in particular embodiments, portions of the foundation 110 formed of a concrete composite may be hollowed out and filled with Barite (also known as Barium Sulphate) to absorb vibrations. In other configurations, other types of material may make-up some or all of portions of the foundation 110 to absorb vibrations. Examples of configurations of foundation 110 are provided below as embodiments of the present invention.
In particular configurations of the present invention, the foundation 110 may be viewed as a large reinforced concrete mass, supported on a series of isolation springs 130 having sufficient internal strength to absorb loads and partially impart them into the hull structure 120. In certain configurations, the large mass of the foundation 110—by itself—may be insufficient to assure compliance with design factors, for example, the avoidance of resonance conditions during operation that would create vibration amplitudes leading to the turbine being shut down. Certain manufactures such a General Electric impose limits on vertical and transverse vibrations; if such limits are exceeded, the gas turbine automatically shuts down. This includes the varying frequencies of the turbine during run up to its operating rotation per minute (rpm) and run down when stopping the turbine.
The foundation 110 thus may be designed with capability to avoid or absorb resonance frequencies at each of the following three modes of operation: run up, operating, and run down. Each may cause vibration amplitudes that shut down the turbine. In particular configurations, the design may avoid resonance at 60 Hz, the operating frequency of certain turbine generators. In other embodiments, the configuration may avoid frequencies other than 60 Hz.
As a recapitulation of certain features above, the foundation 110, itself, may absorb certain forces or kinetic energy that are created by the structure thereon, namely the gas turbine 210 and associated generator 220. Those forces or kinetic energy not absorbed by the foundation 110 may be absorbed by the springs 130. And, those forces or kinetic energy that are not absorbed by the foundation 110 and springs 130 may be absorbed by the hull structure 120, which may have features designed to absorb energy. As referenced above, the springs 130 may also isolate deformations in the hull structure 120 from impacting the gas turbine 210 and associated generator 220. Additional stabilization features may also be incorporated according to certain embodiments.
Because it may not be possible to avoid all frequencies imparted by the operation of the gas turbine 210/generator 220, the foundation 310 may be designed with additional capability to absorb such frequencies. In particular embodiments, this may be accomplished through the use of particular geometric shapes on the lower part of the foundation 310 along with the internal mix of the concrete and steel reinforcement. As seen in
In addition to the above, the actual material for the foundation (which may be a mixture of concrete or other materials) may be based on an analysis that considers a strength of the materials, speed of the cure rate for materials requiring curing, and damping capacity of the materials. As referenced above, a variety of materials may be used in the foundation 310, making the foundation a composite of such materials. Such materials include, but are not limited to, various types of concrete with various mixtures including barite and steel. The overall affect of the foundation design may be to increase its internal damping capability such that it is sufficient to absorb the affect of resonance frequencies.
To ensure that vibration amplitudes do not exceed the limits imposed by turbines manufacturers such as General Electric, certain configurations may include two additional features. First, large structural brackets 324 may be included in the hull structure. These large structural brackets 324 may be designed to absorb any transient horizontal vibration created movement that is imparted thereon. The structural brackets 324 may utilize any appropriate structural design techniques.
Second, a series of hydraulic jacks 340 may be installed between the foundation 310 and the deck 322 of the hull structure. The hydraulic jacks 340 may be installed in precise locations to permit a degree of the turbine 210/generator 220 forces to be absorbed by the mass of the hull structure 320 and the water that the hull structure 320 is floating in. In particular configurations, the hydraulic jacks 340 may adjust the stiffness between the deck 322 and the foundation 310 by, for example, removing or adding the effects of the springs 330. Additionally, in particular embodiments, the hydraulic jacks 340 may be designed such that vibration frequencies are also absorbed by the fluid in the jacks 340 and their associated accumulators.
With reference to
With reference to
Although a hydraulic jack 540 has been shown in this embodiment, other embodiments may utilize other structural features. For example, in another configuration, a plurality of power screws may increase or decrease a spacing between the foundation 510 and the hull structure 520—effectively manipulating the amount of compression on the springs (in embodiments utilizing such springs).
The following is a recapitulation of certain features of various embodiments described above:
In designing the foundation, one or more of the following may be considered:
Although structures and materials may have been described, the present disclosure may not be limited to these specifics, and others may be substituted as it is well understood by those skilled in the art, and various steps may not necessarily be performed in the sequences shown.
While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.
Also, techniques, systems, subsystems and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other products shown or discussed as directly coupled or communicating with each other may be coupled through some interface or device, such that the products may no longer be considered directly coupled to each other but may still be indirectly coupled and in communication, whether electrically, mechanically, or otherwise with one another. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.
