Abstract:
The present invention comprises a modular unit in which all of the components necessary for conditioning the intake air for a combustion gas turbine are contained. The compressors, evaporators condensers and related pumps and control equipment are contained within a weather proof enclosure having sound insulation installed in the walls. The intake air conditioning system includes three loops, a compressed refrigerant loop, a chilled water loop and a condenser cooling water loop with an optional heating loop. The modular unit provides a three loop cooling system for easy connection to both a combustion gas turbine air inlet and to a cooling water tower. The loops comprise a refrigerant loop, a cooling water loop and a chilled water loop and in one embodiment a heating loop to heat the air going to the turbine.

Description:
This is a division of application Ser. No. 09/640,836, filed Aug. 17, 2000, U.S. Pat. No. 6,422,018, which claims the benefit of Provisional application Ser. No. 60/166,486, filed Nov. 19, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and process for heating and/or cooling of the intake air to a combustion gas turbine. More particularly the invention relates to a skid mounted modular unit that is manufactured off site and transported to the turbine location and connected with a minimum of on site construction. Most particularly the invention relates to a process and apparatus that utilize the exhaust heat from the turbine to indirectly heat the intake air to the turbine. 
     2. Related Information 
     In industry combustion gas turbines [C.G.T.&#39;s)] (C.G.T.&#39;s) drive a variety of devices (i.e., generators, gas compressors, pumps, etc.) and are subject to continually changing ambient conditions, which can adversely affect their power output. The combustion gas turbine industry has always struggled with controlling the power of the turbine at varying intake ambient air temperatures. Some problems listed below (not all inclusive) are typical of users of combustion gas turbines have struggled with since the development of the combustion gas turbine: 
     1. Varying inlet temperatures resulting in varying combustion gas turbine power outputs and thus unpredictable work produced. 
     2. Varying temperatures related to increased maintenance and operating costs. 
     3. Conventional inlet chilling (using basic liquid chillers) and heating costs were high. 
     4. Conventional inlet chilling using basic liquid chillers of the reciprocating, screw or centrifugal type refrigeration compressors were not large enough regarding capacity to cool the combustion gas turbine large mass flow rates with redundant systems. 
     5. Basic liquid chillers with their ancillary components (pumps, cooling tower, electrical switchgear, piping, control systems, sound components, weatherproofing costs, buildings, civil work, and field assemble labor) required large physical areas to field assemble. 
     6. Field erected systems have been undependable with regard to guaranteed performance and parasitic electrical loads of the systems have been too high to justify installation. 
     7. Alternate methods of inlet cooling, such as evaporative cooling or water atomization into the combustion gas turbine inlet, while low in initial cost, do not maintain steady inlet temperatures with varying ambient conditions. Since these methods are completely dependent on evaporation of water, the higher the wet bulb temperature, the less effectively they cool. It is typically at high wet bulb temperature conditions that maximum combustion gas turbine output is needed. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a modular unit in which all of the components necessary for conditioning the intake air for a combustion gas turbine are contained. The compressors, evaporators condensers and related pumps and control equipment are contained within a weather proof enclosure having sound insulation installed in the walls. 
     There are many aspects of the present invention that are unique and that have not been known in the prior art. These novel features include but are not limited to: 
     1. A single lift packaged modular combustion gas turbine chilling, control and monitoring system that can be installed without the use of (a) multiple disciplines, (b) engineering and construction site contractors, (c) untested products, (d) multi component vendors (i.e., chillers, pumps, controls, electrical components, etc.), (d) guesswork, (f) field welding, (g) insulation, (h) piping, (i) instrumentation, (j)structural systems, (k) weatherproofing and (l) provisions for extreme systems. 
     2. The present modular system is different from field erected systems in that it: 
     (a) can be operated in hazardous environments without costly “explosion proofing” electrical modifications. 
     (b) responds directly to C.G.T. operator&#39;s inlet air temperature sensing which is part of the operator&#39;s digital control system (D.C.S.). Field erect systems typically respond to chilling fluid temperatures. 
     (c) provides electrical parasitic load (KW) data directly to operator&#39;s D.C.S. console. 
     (d) provides auto-switchover of 100% stand-by pump on condender water or chilling liquid. Field erect systems require operator manual changeover with valves. 
     (e) provides the entire process in fully weatherproof, thermally insulated, and sound attenuated enclosures. Field erected systems offer none of these items and require a building to provide any protection. Field erect systems offer no integrated modular designs on cooling and no optional integrated C.G.T. inlet heating modules for direct integration into the chilling process by way of: 
     1. control system 
     2. piping and valves 
     3. heat exchanger 
     4. electrical system 
     5. commonality of components 
     (f) provides compact, single lift modules, factory assembled, tested, and transportable on major highways to any site. 
     (g) provides portable modules, easily moved to other sites and quickly connected for operation. 
     (h) provides large capacity (cooling tons) modules which use simple 2-flow pass heat exchangers on liquid chilling [(evaporator-drawing 01)] and condensers [(drawing 01)], eliminating extensive and complicated series and parallel flow arrangements common to some field erected systems. 
     (i) provides available multiple centrifugal compressors on single heat exchanger vessels for stand-by capability (50%/50%) and very efficient operation at partial loads. No other system offers this. 
     (j) provides fully independent microprocessor control and safety logic for each centrifugal compressor. 
     (k) uses R-134a “chlorine free” refrigerant in capacities over 1,500 tons, an exclusive. 
     (l) has the ability to control module temperature (ventilation, cooling, heating, and/or humidity control) surrounding all process system components so they are not affected by changing outdoor weather, and exclusive. 
     (m) is fully assembled, pre-piped, pre-wired, insulated, and tested prior to shipment, and exclusive. 
     (n) has the ability to reclaim C.G.T. exhaust heat through thermal oil/E.G. liquids and provide heating at C.G.T. inlet with the common components of the chilling system is unique to this process. 
     (o) provides centrifugal compressors on liquid chilling systems are aircraft derivative design for fast start and fast stop of compressors, saving energy and eliminating costly “coast down” lubrication systems. 
     (p) provides single point power connections for entire system electrical distribution, safety, back up, and operation, a unique feature. 
     (q) provides reclaiming inlet chilling coil condensate to cooling tower make-up water stream for less make-up water usage and to improve tower efficiency. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a side elevational view of one embodiment of the skid mounted modular combustion gas turbine intake air conditioner of the present invention. 
     FIG. 2 is a top plan view of the embodiment shown in FIG.  1 . 
     FIGS. 3,  3 A, and  3 B are a simplified flow diagram showing the process using one embodiment of the invention. 
     FIGS. 4,  4 A,  4 B, and  4 C are the embodiment of FIG. 3 with a heating section added. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The modular unit of the present invention provides a three-loop cooling system for easy connection to both a combustion gas turbine air inlet and to a cooling water tower. The loops comprise a refrigerant loop, a cooling water loop and a chilled water loop. The refrigerant loop contains a normal compressor, condenser and evaporator cycle with the condenser being cooled by cooling water from the cooling water loop. The refrigerant evaporator cools the water in the chilled water loop which is circulated to the combustion gas turbine air inlet. The chilled water takes heat from the combustion gas turbine inlet air; the refrigerant takes heat from the chilled water; and lastly the heat is finally removed to the atmosphere by a standard evaporative cooling tower via the cooling water loop. 
     The success of the modular unit is that the refrigerant is contained within the module and the temperature of the chilled water can be accurately controlled by circulation of refrigerant. There is no need to connect the refrigerant to the combustion gas turbine inlet air coolers. The use of the chilled water as opposed to using the cooling tower water allows the use of a smaller heat exchanger at the combustion gas turbine inlet as well as lower circulation rates to the exchanger. 
     The present modular combustion gas turbine intake air conditioner comprises: 
     (a) a base; 
     (b) a first refrigerant compressor mounted on said base, said refrigerant compressor having a refrigerant compressor suction and a refrigerant compressor discharge; 
     (c) a first refrigerant compressor driver mounted on said base and mechanically connected to said refrigerant compressor: 
     (d) a refrigerant condenser mounted on said base for indirect heat exchange between cooling water and refrigerant, said refrigerant condenser having a refrigerant inlet connected to said first refrigerant compressor discharge by a conduit, a refrigerant outlet, a condenser cooling water inlet and a condenser cooling water outlet; 
     (e) a conduit connected to said condenser cooling water outlet for connection to a cooling water return conduit; 
     (f) a first cooling water pump mounted on said base, said first cooling water pump having a first cooling water pump suction and a first cooling water pump discharge; 
     (g) a first cooling water pump driver mounted on said base and mechanically connected to said first cooling water pump; 
     (h) a conduit connected to said first cooling water pump suction for connection to a cooling water source; 
     (i) a conduit connecting said first cooling water pump discharge and said condenser cooling water inlet; 
     (j) a refrigerant evaporator mounted on said base for indirect heat exchange between refrigerant and chilled water, said refrigerant evaporator having a refrigerant inlet, a refrigerant outlet, a chilled water inlet and a chilled water outlet; 
     (k) a conduit connecting said refrigerant inlet to said refrigerant condenser outlet; 
     (l) a conduit connecting said refrigerant outlet to said first refrigerant compressor suction; 
     (m) first chilled water pump mounted on said base, said first chilled water pump having a first chilled water pump suction and a first chilled water pump discharge; 
     (n) a first chilled water pump driver mounted on said base and mechanically connected to said first chilled water pump; 
     (o) a conduit connecting said first chilled water pump discharge to said chilled water inlet; and 
     (p) a conduit connected to said first chilled water pump suction for connection to a heat exchanger located in the air intake of a combustion gas turbine. 
     Preferably the present modular combustion gas turbine intake air conditioner according has a housing mounted on said base and enclosing said first refrigerant compressor, said first refrigerant compressor driver, said refrigerant condenser, said first cooling water pump, said first cooling water pump driver, said refrigerant evaporator, said first chilled water pump, said first chilled water pump driver and all of said conduits. 
     Preferably in the present modular combustion gas turbine intake air conditioner all of said drivers are electric motors and further comprising a wiring harness contained within said housing and providing electrical power to each of said drivers, said wiring harness having one connection between said wiring harness and an external electrical power source. 
     Referring now to FIG.  1  and FIG. 2 the general layout and construction of the modular unit can be seen. The entire unit is mounted on a skid  100 . The main pieces of equipment include the chilled water pumps  110  and  112 , each with a driver  210  and  212 , respectively, the condenser water pumps  114  and  116  with their drivers  214  and  216 , respectively, the refrigerant compressors  118  and  120  with their respective drivers  218  and  220 , the refrigerant evaporator  122  and the refrigerant condenser  124 . The compressors take suction from the evaporator  122  via suction lines  909  and  910  respectively and discharge into the condenser  124  via discharge lines  911  and  912 . The piping is numbered to correspond to the flow diagram of FIG. 3 for easy reference. 
     The motor control panel is shown at  126  with the compressor starters shown at  128  and  130 . A differential pressure sensor and switch  132  is provided between the chilled water inlet  901  and outlet  902  to the evaporator to shut down the pumps if the evaporator becomes fouled. Flanged connections are provided for chilled water inlets  903  and  904  (from the combustion air inlet heat exchanger—not shown) to the chilled water pumps  110  and  112  respectively; the chilled water outlet  905  (to the combustion air inlet heat exchanger—not shown); condenser water inlets  906  and  907  (from the cooling water tower—not shown) to condenser water pumps  114  and  116  respectively; and condenser water outlet  908  (to the cooling water tower—not shown). 
     The whole skid-mounted unit is surrounded by a modular container  101  having two separate doorway entries  103  and  105 . Such ancillary equipment as control valves, lighting and ventilation may be included but are not shown. 
     Also conspicuously shown are the redundancy of the pumps and compressors. The modular unit includes the ability to automatically switch from one to the other upon failure or shut down of the one operating. 
     Referring now to FIG. 3, a flow diagram of the combustion gas turbine inlet air cooling process utilizing the present invention is shown. The process begins with heat being removed from the combustion gas turbine  26  inlet air through the fin tube heat exchanger  31  (commonly called the inlet chilling coils). This heat is transferred from the inlet chilling coils  31  to the chilling fluid and is carried to the chilling process through the liquid return line  38  where it enters the operating chilled liquid pump  110  or  112 , noting that one pump is 100% stand-by. An isolation valve  10  is provided to facilitate pump service. The fluid is pumped through vibration isolator  6 , check valve  15 , balancing/isolation valve  10 ′, and into the basic liquid chilling unit heat exchanger section  122  (evaporator) where heat is removed by indirect contact with evaporating refrigerant. The refrigerant is compressed in either of compressor  118  or  120  and then condensed in condenser  124  where the heat is removed by condenser water which in turn is cooled in the cooling tower  29  through an evaporative process (adiabatic) thereby reducing the condenser water temperature to acceptable levels and which is returned to the condenser through the condenser water supply line  30   a , entering the operating condenser water pump  114  or  116 , noting that one pump is 100% stand-by, through a shut-off/isolation valve  9 . The condenser is then circulated through the condenser  125  again in a continuous process of heat rejection. Likewise the chilled liquid is recirculated to the inlet chilling coils  31  via line  28 . 
     A unique feature of the present system is that the condensate water formed at the inlet chilling coils  31  is piped to the cooling tower  29  basin via line  37  to provide a water saving source of tower make-up water which replaces evaporated water from the cooling process. Typically this water is much cooler than existing basin water contributing to cooling tower efficiency. Since the condensate water from the inlet chilling coils  31  is pure, it helps reduce cooling tower blowdown used to keep total dissolved solids low. Usually the water flows from the collection pan  36  by gravity through the drain line  37  to the cooling tower basin. 
     In another embodiment of the invention the inlet air may be heated to prevent ice formation and subsequent damage to the turbine. Essentially the process and apparatus are the same with a hot oil/ethylene glycol loop. This process is shown in the simplified flow diagram of FIG.  4 . Ambient air enters the chilling coils  31  and is heated with a 54% ethylene glycol solution flowing through the inlet coils  31  via supply and return lines  38  and  39 , which is being circulated by the operating chilled liquid pump  110  or  112 . The ethylene glycol is pumped through the ethylene glycol/thermal oil heat exchanger  40  where the constant flow ethylene glycol is heated by the thermal oil and continues to supply heat to the inlet coils  31 . In the thermal oil loop, the thermal oil pump  42  circulates from the ethylene glycol/thermal oil heat exchanger  40  through the thermal oil/exhaust gas exchanger  41  where the high temperature exhaust gas stream  43  heats the thermal oil. 
     The exhaust gas is taken from the main combustion gas turbine  26  exhaust stream at a point  44  and returned as closely as possible at point  45  to minimize thermal and acoustical impact on the combustion gas turbine exhaust stack attenuators. 
     The exhaust gas inlet  43  is allowed to flow to heat exchanger  41  when the system control sensor  46  enables the isolation damper  48  to full open position. Control damper  49  starts to modulate also in response to Temperature indicator proportioning signal. Forced air fan  50  operates at full speed to overcome the pressure drop of exchanger  41  with respect to exhaust gas pressure. When proper exhaust gas glow has been established over exchanger  41 , both fan  50  speed and/or control damper  49  modulator controlled by temperature indicator  47  will maintain a constant loop temperature and combustion gas turbine inlet temperatures. When the combustion gas turbine inlet is satisfied or in non heating modes, the fan  50  will stop, the control damper  49  and isolation damper  48  will fully close to isolate the heating coil from the exhaust gas stream flow. Oil pump  42  will continue to circulate until the oil and ethylene glycol loop temperatures are reduced to acceptable levels. 
     A motorized bypass loop  52  is included in the module to allow the ethylene glycol flow to bypass the chilling evaporator  122 , saving energy and avoiding exposing the evaporator  122  to excessive temperatures. The motorized bypass loop is fully automatic based on temperature indicator  47  set points, or can be manually selected by the combustion gas turbine operator. Also at initiation of inlet heating, balancing valve  55  limits the ethylene glycol loop side flow to exchanger  40  at a preset rate to accomplish design temperatures, and motorized control valve  53  closes to a preset value to force a portion of ethylene glycol loop flow through exchanger  40 . Once the valves are at their preset points, the ethylene glycol pump  3  (chilled water pump), the thermal oil pump  42  and modulating functions of the fan  50  and damper  49  will commence.