Abstract:
A trailer mounted mobile power generation system provides electrical power at locations where it is needed, either separate from or as a supplement to power from an electrical power distribution grid. A jet engine, a free turbine and an electrical power generator in a single common road transportable trailer. The trailer complies with weight and height limitations imposed by transportation authorities. The jet engine drives the turbine, which in turn drives the electrical power generator. Power levels on the order of 20 megawatts are generated while maintaining noise and combustion product emission levels within presently specified regulatory limits.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to generation of electrical power, and more particularly to trailer mounted, mobile systems for generation of electrical power. 
     2. Description of the Related Art 
     Mobile power generation systems capable of delivering several or more megawatts of power have been known to offer certain advantages compared to power delivered from the electrical power or utility distribution grid. The mobile power generation systems can provide power as needed at times of peak demand or of brownout in the distribution grid, or in cases of need because of some emergency or other problem in the distribution grid as a result of a power grid failure or some other type of disaster. The mobile power generation systems also can be located at places distant from the distribution network where there is a need for power. There is then no need for the delay or expense of arranging for or construction of power lines to the distant or remote places. 
     Some years ago, there were attempts made to provide electric power in trailer mounted generator systems. An example of such a trailer mounted generator system is described in a magazine article entitled “Megawatts on Wheels” written by C. F. Thompson, C. R. Boland and E. Bernstein in the March 1971 issue of Combustion, pages 24-30. For some reason, these types of generator systems did not, so far as is known, achieve any extended years of use and were not widely adopted. 
     As noted above, mobile power generation systems have certain desirable features and advantages. They have again recently become the subject of interest. However, there are a number of intervening factors which give rise to problems with these earlier types of trailer mounted generator systems. 
     For optimum use, such a system needs to comply with weight and height restrictions from relevant highway regulatory and governmental agencies. Also, there are environmental limitations on the type and acceptable concentration levels of combustion waste products produced by this equipment. In addition, noise from the various components of the generator systems must be kept within presently established regulatory limits. 
     There were competing considerations regarding mobile power generation systems of this type. On the one hand, limits on weight and size of the systems had to be observed if the systems were to be highway transportable and thus available for widespread use. In conflict with this were the environmental and noise abatement considerations. Further, mobile power generation systems should be self-supporting in that they could bring to the site all equipment necessary to assemble the system in a relatively few days without the need for other equipment such as cranes, hoists and the like. It was felt by at least some that achieving suitable limits on combustion gas product emissions and noise levels could not be achieved while complying with height and weight limits for highway travel. 
     SUMMARY OF THE INVENTION 
     Briefly, the present invention provides a new and improved mobile, trailer-mounted power generation system. A gas generator burning a hydrocarbon fuel for creation of combustion gases is operably interconnected with a free turbine which receives combustion gases and rotates a turbine shaft in response thereto. An electrical generator is mounted in communication with the free turbine for the generation of electricity upon rotation of the turbine shaft. A trailer body which is towable by a conventional tractor or truck is provided having a floor on which the gas generator, free turbine and electrical generator are mounted. The trailer body has end and side walls and a roof enclosing the gas generator, free turbine and electrical generator. 
     The trailer body is provided with an air inlet near one end for passage of air to the gas generator, and the free turbine has an exhaust for exit of the combustion gases. The trailer body has a combustion gas outlet formed in a side wall thereof for exit of the combustion gases from the free turbine. The gas generator, free turbine and electrical generator each have a longitudinal axis about which certain of their power generating components rotate during their operation. The longitudinal axes of the gas generator, free turbine and electrical generator are longitudinally aligned along a common axis along the longitudinal extent of the floor of the trailer body. 
     With the present invention, the mobile, trailer-mounted power generation system is easily connectable to other road transportable units which provide for removal of undesirable components of the combustion gases without increasing the height or width of the trailer body of the power generation system. The mobile, trailer-mounted power generation system permits modularization of components to achieve generation of electrical power from a road transportable unit while complying with height and weight limits for highway travel and also meeting both noise and environmental requirements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a mobile, trailer-mounted electrical power generation system according to the present invention deployed with a number of support trailers at a power generation site. 
     FIG. 2 is an isometric view of the mobile, trailer-mounted electrical power generation system of FIG.  1 . 
     FIG. 3 is a schematic representation in plan view of the interrelation of several components within the power generation system shown in FIGS. 1 and 2. 
     FIG. 4 is plan view of an alternate deployment to that of FIG. 1 of a mobile, trailer-mounted electrical power generation system according to the present invention at a power generation site. 
     FIG. 5 is an isometric view of another embodiment of a mobile, trailer-mounted electrical power generation system of the present invention. 
     FIG. 6 is a schematic representation in plan view of the mobile, trailer-mounted electrical power generation system of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring first to FIG. 1, there is shown in plan view an exemplary mobile power production installation  10  that has been established at a desired power generation site, either remote or in connection with an established power generation network or grid in order to provide electrical power. The exemplary installation  10  includes several trailer systems  12 ,  14 ,  16 ,  18 ,  19  and  20 , each in the form of an enclosed trailer. At the power generation or deployment site, the trailers are supported on jacks in appropriate level positions. Access to the interior of trailers  12 ,  14  and  20  through conventional, lockable doors is provided by as set of steps S, ladders or the like. 
     Trailer system  12  is a mobile power generation system according to the present invention to be described in further detail below. Trailer  12  is a size compatible with applicable highway transport regulations, 10 ft., 6 in. in width, 13 ft., 6 in. in height and 55 ft. long for road travel. Trailer  14  is a controls trailer that houses controls used to monitor and control the operation of the power generation equipment within the trailer  12 . Trailers  16 ,  18  and  19  enclose equipment that is used to remove undesirable emissions from the combustion gases formed by the components of trailer  12 , such as NOx, CO and the like. In the preferred embodiment, this is accomplished through the use of selective catalytic reduction (“SCR”) of the emissions. 
     Trailer  16  contains an injection chamber where treating chemicals are injected into the stream of exhaust combustion gases entering from trailer  12 . Trailer  18  contains a mixing chamber where the exhaust combustion gases and injected chemicals enter and are thoroughly mixed. Trailer  19  contains a reaction chamber where the mixed products enter from the mixing chamber in trailer  18  and are contacted by reduction catalysts suitably disposed to contact the entering gas mixture and react with the indesirable combustion gas products. An outlet is provided in the reaction chamber trailer  19  for venting of the treated exhaust gases to the atmosphere. The SCR techniques may, for example, be those according to U.S. Pat. Nos. 5,601,792 and 5,431,893, which are incorporated herein by reference. Trailer  20  is used to store chemicals and other supplies and to house mixing tanks for forming the urea solution injected into trailer  16  in the SCR process to clean the combustion gas emission stream from trailer  12 . 
     FIG. 2 illustrates an exemplary mobile power generator system trailer  12  with trailer having a floor  22 , end walls  23  and  25 , side walls  27  and  29  and a roof  31 . Walls  23 ,  25 ,  27  and  29  and roof  31  are shown in phantom so that the power generating components of the trailer  12  may more clearly be seen. FIG. 3 illustrates certain components of the system of FIG. 2 schematically to illustrate their functional interconnection more clearly. It is noted that the generator system trailer  12  forms a complete and essentially closed system for the generation of electrical power. 
     The power generator system trailer  12  includes a gas generator  24  operably interconnected with a power generation turbine, or “free” turbine,  26  to supply combustion exhaust gases to the free turbine  26 . The gas generator  24  preferably comprises a Pratt &amp; Whitney FT-4 gas generation unit positioned lengthwise on the trailer  12  along a common longitudinal axis L of rotation of the rotating power generation components of the gas generator  24  and free turbine  26  mounted on the trailer floor  22 . The FT-4 of gas generator  22  is a relatively lightweight aircraft gas turbine which receives fuel (either natural gas or liquid fuel such as jet fuel or diesel) from a conventional storage tank or other source of supply (not shown). The gas generator  22  burns the fuel provided it to form exhaust combustion gases which are furnished to the free turbine  26  through an enclosed cylindrical hood or gas passage. The cylindrical passage or duct for the combustion exhaust gases from the gas generator  24  extends between the outlet of gas generator  24  rearward of its guide vanes to an inlet of the free turbine  26  forward of its nozzle guide vanes. In the embodiment of FIGS. 1-3, the free turbine is Model FT-4 gas turbine originally made by Pratt and Whitney Aircraft and available from various sources. In the embodiment of FIGS. 5 and 6, the free turbine is a “Zorya” PA gas turbine, Model UGT-2500 available through ZDRYA Power (USA) of Annapolis, Md. 
     The power generation turbine  26  is known as a “free” turbine because the shaft of the turbine  26  is not mechanically interconnected with a shaft within the gas generator  24 . Thus, the turbine  26  is powered by the exhaust combustion gases formed by the gas generator  24 . The free turbine  26  includes a shaft supported by a front and a rear bearing  30 ,  32  (see FIG. 3) and having turbine blades mounted therewith to develop rotational movement in response to receipt of the gases from gas generator  24 . The free turbine  26  also has an output shaft  34  that is operably interconnected with an electrical generator  36 . The generator  36  is capable of converting the rotational energy of the output shaft  34  into electrical power. A suitable device for use as the electrical generator  36  is a Peebles 3-phase, 13,800 KVA brushless, air-cooled 25 MW generator. It will be understood that the generator  36  is operably interconnected in a cabinet C with power cables or other electrical transmission means for the supply of electrical power created by the generator  36 . 
     The transport trailer  22  also supports a gas generator air intake through which external air is supplied to provide a combustion mix in the gas generator  24  with the fuel supplied it. A free turbine oil cooler intake is likewise mounted upon the trailer  22  when the system  12  is set up for power generation. A gas turbine lubrication system  42  is operably interconnected with the gas generator  24  to supply lubricant thereto, while a free turbine lubrication system  44  is operably interconnected with the free turbine  26  in order to supply lubricant to the free turbine  26 . 
     A L-shaped exhaust elbow  46  is disposed between the free turbine  26  and the electrical generator  36  so that exhaust gases exiting from the free turbine  26  are diverted away from the generator  36  for processing. FIG. 1 illustrates the elbow  46  interconnected with a cylindrical outlet port  48  that is, in turn, secured in sealing engagement with an inlet port  50  to the injection chamber trailer  16 . As has been set forth, the injection chamber trailer  16 , mixing chamber trailer  18  and reaction chamber trailer  19  receive the effluent combustion gases from the power generator trailer  12  so that the exhaust combustion gases may be treated to reduce undesirable emissions such as NOx, CO and the like to environmentally acceptable levels. 
     The exhaust elbow  46  is in the form of a generally L-shaped outwardly expanding tubular member connected at the outlet of the free turbine  26  to receive exhaust combustion gases and divert and convey these gases from their original axis of travel along the longitudinal axis L of flow through the gas generator  24  and free turbine  26  at a laterally outwardly extending angle A, preferably perpendicularly at an angle of 90° to the longitudinal axis L. The gases diverted in exhaust elbow  46  exit outwardly through the outlet port  48  formed in one of the side walls  27  or  29  of trailer  12 . 
     It is to be noted that the exhaust combustion gases from the free turbine  26  and gas generator  24  are vented laterally through a side wall  27  or  29  and not upwardly through the roof  32  of the power generator trailer. This permits connection of the trailer  12  at its own elevation to various configurations of emission treatment equipment, noise abatement equipment and the like. For example, FIG. 4 shows the trailer  12  connected at its outlet port  48  to a modified exhaust gas treatment trailer  116  which can provide a simplified SCR treatment of the type discussed above in the present application. Other structure in FIG. 4 like that of FIGS. 1-3 bears like reference numerals. With prior roof-mounted outlets from the earlier free turbine systems, a crane and other expense would have been required to establish any connection. This would have involved additional expense in equipment and time. Thus the present invention provides a mobile, trailer-mounted power generation system which is road transportable to a deployment site where electrical power generation is required. Further, the trailer  12  meets applicable highway regulatory size limits and is connectable at the power generation site to emission control equipment and noise abatement equipment also mounted in trailers without the need for cranes, booms or other special purpose construction equipment. 
     Those of skill in the art will recognize that many changes and modifications may be made to the devices and methods of the present invention without departing from the scope and spirit of the invention. Thus, the scope of the invention is limited only by the terms of the claims that follow and their equivalents.