Combined Cycle (FGD)

Power-Gen International ‘97 Paper

″″Capacity Enhancement for Simple and Combined CycleGas Turbine Power Plants ″″

Power-Gen International ‘97

by

Stephen J. Molis, P.E., Fern Engineering, Inc.

Philip Levine, Fern Engineering, Inc.

Robert Frischmuth, Electric Power Research Institute

9/25/97

Capacity Enhancement for Simple Cycleand Combined Cycle Gas TurbinePower Plants -- 9/25/97

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Introduction

Over the last several years, the Electric Power Research Institute (EPRI) has developed a body ofinformation to quantify the costs and benefits of various approaches to capacity enhancement ofcombustion turbines (Refs. 1 and 2). Fern Engineering, Inc., a gas turbine design and consultingfirm located in Pocasset, MA, has been EPRI’s contractor for this work.

One of these techniques, evaporative cooling using direct water spray and overspray wasidentified as having potential benefit to utilities. Inlet cooling is attractive for those gas turbineswhere the power increases markedly as the compressor inlet temperature is reduced. The typicalvariation of the performance of heavy duty gas turbines is depicted in Figure 1.

Figure 1 Typical Performance vs. Temperature for Heavy Duty Gas Turbines

Evaporative cooling is limited by the difference between the dry bulb and wet bulb temperatures.If sufficient water can be introduced into the air such that the air becomes fully saturated, the airtemperature will be reduced to the wet bulb temperature. In doing so, the turbine power willincrease as shown above.

The amount of cooling is limited by the potential for icing as the air flow speeds up in thebellmouth and the static air temperature drops. The icing limit is engine dependent but typicallyvaries from 40 °F to 50 °F. Thus, evaporative cooling must be limited at low ambienttemperatures to avoid the potential for icing.


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Generally, the retrofit of inlet cooling systems is more cost effective for efficient (modern) gasturbines where the specific power (ratio of power to air flow) is high.

Evaporative Cooling with Media

Media type coolers are installed on many gas turbines throughout the world. Evaporativecooling is dependent on the evaporation rate and the contact surface area between the wettedsurface and the air. Specially designed contact media that packs a very large surface area into asmall volume is essential to the practical application of this approach (Ref. 3). Other applicationcriteria include limiting the air speed to reduce the pressure drop or to strip away droplets ofmoisture from the wetted surface. Typically the air speed must be reduced to about 400 fpm atthe face of the media, requiring a relatively large evaporative cooler structure. A typical inletduct velocity is about 2500 fpm. Untreated municipal water is frequently used, but care must betaken to avoid water droplet carry-over that could foul the compressor. Silica deposits resultingfrom untreated water are difficult to remove.

Media type coolers have several major drawbacks. First, they require a relatively large inlethouse to reduce the air speed at the face of the media to insure reasonably efficient cooling. Assuch, media coolers cannot be easily retrofitted into existing inlets. Also, the size and cost of thestructure is relatively independent of the cooling potential. Second, maintenance is oftenrequired due to plugging and need for media repair.

Direct Spray and Overspray

Direct spray evaporative cooling systems using a fine water spray (or fog) can be more easilyretrofit into existing inlet structures than the media type design. In addition, such systems havethe potential for operating at higher efficiencies thus providing increased power. A number ofoperators have recognized the potential benefits of direct spray cooling and have implementedsuch systems (Ref. 4). While these systems are reported to be quite effective, EPRI and Fernjointly developed a concept to improve the efficiency of direct spray coolers through the use ofoverspray. This concept was aimed at developing a 100% efficient evaporative cooler thusgarnering the maximum power benefit. In addition, additional power gains appeared possible assmall overspray droplets evaporate in the first few compressor stages.

This concept was initially studied for potential application on a General Electric, Model MS-7001E at Utilicorp United’s Ralph Green Station in Pleasant Hill, Missouri. The results werepromising and EPRI and Utilicorp United embarked on an EPRI Tailored Collaboration Projectto develop and demonstrate the concept. A development program was undertaken to design asystem that could optimally benefit from a direct spray and overspray system within the boundsof the state-of-the-art of spray (fog) generators. This paper addresses the results from this project(Ref. 5).

The goal was to maximize the power output of the gas turbine during the hot summer monthswhen output power decreases. An innovative direct spray evaporative cooler, called an EPRISpray Cooler (patent pending), was developed, designed and installed in the inlet during thesummer of 1996. The spray cooler was subjected to a demonstration test in August 1996.

The EPRI spray cooler uses a fog water spray to saturate the air by evaporative cooling. One of


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the innovations of this system is that enough water is sprayed into the inlet to oversaturate theair. When the air is fully saturated, the excess water (overspray) remains entrained in the air.However, large overspray droplets are removed from the air by a large droplet eliminator (LDE),leaving an overspray composed of fog sized droplets that are ingested directly into thecompressor to obtain further cooling benefit. Using this combination of evaporative cooling andoverspray, the base load power may be increased by as much as 8.1 MW (~14%) at the designoperating conditions.

As Utilicorp’s goal was to increase summer peaking capacity as much as possible, it was alsodecided to increase the amount of water injected into the combustor beyond the level used forNOx control. With both changes implemented, the unit is capable of delivering an additional 11MW at the design operating conditions; an increase of about 18% at base load.

Summary of Results

1� The EPRI Spray Cooler achieved 100% saturation on all days tested. Air temperature isreduced quickly to the wet bulb temperature once the proper number of spray stages areactivated. In contrast, media type evaporative coolers typically achieve 80 to 90% saturation.

2� The power increase from evaporative cooling is about 3.5 % for every 10 °F (5.6 °C) ofcooling. This is consistent with the OEM performance curves.

3� The power increase resulting from overspray is about 5% for every 1% overspray (overspraywater mass is expressed as a percentage of inlet air mass).

4� No unusual differences in the compressor pressure signature were observed while the systemwas operating at high levels of overspray and water injection. Therefore, compressor surge isnot expected using this capacity enhancement technique on MS-7001 gas turbines.

5� Spray droplets emitted from the nozzles were found to agglomerate into larger droplets.Thus, more spray is removed (~70%) by the Large Droplet Eliminator (LDE) than wasoriginally anticipated (~58%), and less overspray is available. This verified the need for theLDE in the system.

6� Operation at maximum water injection was achieved at both base and peak loads with andwithout overspray. The power gain resulting from water injection is about 0.77 % for each10 gpm (37.85 liters/min) increase in water injection rate.

7� The maximum base power predicted at the design conditions (97 °F [36°C] , 34% RH) is73.2 MW; an increase of 17.7 %. The power gain attributed to each enhancement is:• Maximum water injection ~ 4.7 % gain• Evaporative cooling ~ 10.2 % gain• Overspray ~ 1.8 %

Another 5.5 MW can be expected if operated at peak load.

8� Increased water injection reduces NOx emissions substantially. When the water to fuel ratiowas increased from ~ 0.2 to ~ 0.8, NOx emissions were reduced by about 60%. A smallerreduction in NOx results from evaporative cooling and overspray.

9� Analyses of the drain water samples support some beneficial air scrubbing effects when thespray cooler is operating.


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10� Most of the testing was performed with a dirty compressor. With the dirty compressor, gasturbine power at base load was 4% to 7% lower than predicted based on the OEMperformance curves (new and clean compressor). After washing the compressor the powerwas restored to within 2% of the power with a new and clean compressor.

Ralph Green Plant

The General Electric MS-7001E gas turbine at Utilicorp's Ralph Green Plant was installed in1981 and is generally operated at base load power in peaking service. At design conditions, theunit is base load rated at 60.9 MW with water injection for NOx control. Although the unit hasdual fuel capability, it is fired exclusively using natural gas. The unit was supplied with G.E.'sstandard skid mounted water injection system to control NOx to levels below 92 ppm.

The MS-7001 is a single shaft turbine designed in 1966 for domestic power generation service.Development of the Model E design began in 1973. A complete description of the Model Edesign is provided in Ref. 6. The unit is controlled by GE's Speedtronic Mark II system.Utilicorp uses a separate programmable logic controller (PLC) to control water injection. TheEPRI spray cooler is computer controlled using software developed by Fern for this application.

Gas Turbine Inlet Housing and Duct

Figure 2 illustrates the arrangement of the inlet duct. Inlet air enters through an elevatedhorizontal inlet house. The original inlet house had a two-stage filter consisting of inertialseparators and a bank of high efficiency air filters. Downstream of the inlet house, the air splitsinto dual horizontal "pantleg" ducts. The pantlegs are fabricated in sections, the last of whichcontains silencers. After leaving the silencers the air passes through a trash screen and enters acommon elbow and vertical duct leading to the compressor inlet plenum.

The EPRI Spray Cooler

The EPRI spray cooler is designed to augment the power output by cooling the inlet air, whichincreases the air density thereby increasing the mass flow, pressure ratio and power. The cooleruses a fog spray of water to saturate the air through evaporative cooling. In this system,however, additional water is sprayed into the inlet to oversaturate the air. Large droplets that donot evaporate are removed from the air with a mist eliminator leaving an overspray composed offog sized droplets that are ingested directly into the compressor. Using the EPRI spray cooler,the base load power output may be increased by as much as 8.1 MW (~14%) at the designoperating conditions.

The spray cooler is composed of three major components; a spray delivery system, a watertransfer system and a mist eliminator. Figure 2 illustrates the spray cooler components. Thespray delivery system consists of an array of fog nozzles installed in the inlet compartment. Thewater transfer system, installed outside of the inlet duct, delivers demineralized water to thespray delivery system through interconnecting piping. Finally, the mist eliminator, termed alarge droplet eliminator (LDE), is installed in the inlet house downstream of the spray deliverysystem to remove large water droplets from the air stream.


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Figure 2 Inlet Configuration and EPRI Spray Cooler Configuration

During the development phase, research was conducted to identify the most appropriate spraysystem. A specification was developed and proposals were solicited from several spray systemmanufacturers. At the heart of the specification was the requirement that the spray systemproduce droplets as small as possible. Small droplets are desirable as the evaporation rateincreases with decreasing size. In addition, it is generally known that large water dropletsentrained in the inlet air can lead to erosion of the compressor airfoils. Thus, specifying a nozzlethat generates small droplets mitigates these potential concerns.

The initial specification called for the 90 % of the mass to be in droplets less than 10 µm indiameter. However, after receiving the bids it became apparent that droplets of that size couldnot be reasonably achieved given the current state of the art. Vendors were also requested tosubmit sample nozzles and tests were performed to confirm nozzle performance. These testswere used to select the nozzle with the best spray characteristics. The test results from the nozzleselected for this application showed that 90 % of the mass was in droplets less than 22 µm indiameter.

After the spray system supplier was selected, a small array of nozzles was fabricated and spraytests were conducted in a facility that duplicated actual flow conditions in the inlet duct. Severalmist eliminator configurations were tested before selecting the most appropriate LDE design.During those tests it became apparent that droplet agglomeration occurs as a result of interactionof the sprays of adjacent nozzles. This discovery confirmed the need for the LDE in the systemas its purpose is to remove large droplets from the air stream, while permitting smaller droplets(overspray) to be carried downstream into the compressor.

Prior to installation of the spray system, Utilicorp modified the air inlet housing. The inertialseparator was removed and replaced with a simple bird screen. The inlet air filter bank andsupport structure were also removed. Water drains were added to the floor of the inlet housing.The floor mounted implosion doors were removed and new doors were installed in the walls


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downstream of the LDE. Finally, a structural frame was added to support the LDE.

Spray Delivery System

The spray delivery system and water transfer system were manufactured by Mee Industries, Inc.in El Monte, California to specifications prepared by Fern for EPRI. The spray delivery systemis composed of an array of stainless steel tubes containing the spray nozzles. The nozzle array islocated in a vertical plane just downstream of the inlet air entrance (Figure 3). The nozzle arrayis partitioned into 8 stages with each stage configured with multiple horizontal legs of tubingeach containing a number of nozzles. High pressure water is delivered to the nozzles to producea fine hydraulically atomized water spray. Figure 4 illustrates the fog spray emitted during thesingle nozzle test. The arrangement results a uniform dispersion of spray droplets into the airstream.

Figure 3 Spray Nozzle Array


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Figure 4 Nozzle Fog Spray Pattern

Water Transfer System

The water transfer system supplies high pressure demineralized water to the spray nozzleheaders. The system consists of two identical skid mounted water transfer assembliesunderneath the inlet house. Each skid contains two electric motor driven pumps along withpiping, valves, meters and instrumentation required to deliver and control the flow of water tothe nozzle arrays. Control signals from on-board sensors are directed to dedicated skid mountedfog control panels for each pump and piping leg. Pump flow and pressure sensors, and switchesfor low suction pressure and high water temperature are included for each pump. Figure 5 showsthe equipment arrangement.


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Figure 5 Water Transfer System

Large Droplet Eliminator

The large droplet eliminator (LDE) is a horizontal flow vane type mist eliminator supplied byThe Munters Group in Ft. Myers, Florida to specifications written by Fern for EPRI. The LDE ismounted in the inlet house downstream of the nozzle array and consists of modules covering theentire inlet cross section. The modules are manufactured using polypropylene with sine curveshaped vanes. The LDE is shown in Figure 6.

The vane configuration and spacing were designed to pass a high percentage of small droplets,while removing a high percentage of large droplets. Thus, small overspray droplets that remainentrained in the air flow are passed through the vane openings, while large droplets impinge onthe vane and are drained down the vanes. Adjacent modules direct the flow into commonvertical channels between the modules, into the drainage sump at the bottom of the LDE, and outdrain in the duct floor.


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Figure 6 Large Droplet Eliminator

System Instrumentation

In addition to the instrumentation provided on the water transfer system skids, additional sensorswere installed and the data was sent to the spray control system computer, as described below.

• A weather station was installed to measure ambient temperature, pressure and humidity.• Drains were installed in the inlet duct floor to remove water exiting the LDE and

accumulating on the floor. A flow transmitter was installed in a common drain line tomeasure the drain flow. Flow data is directed to the spray cooler control system computerand used to determine the overall efficiency of the spray cooler system.

• Compressor inlet temperature, and compressor discharge temperature and pressure data fromthe OEM sensors used in the gas turbine control system are also input into the computer.

• A high temperature dynamic pressure sensor was installed in a borescope inspection port inthe compressor casing near the 17th stage. This sensor was installed as a precaution to aid inidentifying the potential onset of compressor rotating stall when high levels of wateroverspray are injected. Data from the pressure sensor is transmitted to the spray coolercontrol system computer and analyzed using a signal analysis software package.


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Spray Cooler System Controls

A personal computer (PC) is used to operate, control and monitor the spray cooler using softwaredeveloped by Fern. The computer receives data from the weather station, gas turbine sensors,compressor pressure transducer, and the fog control panel.

The control software consists of a series of screens designed to operate and control the spraycooler in a windows environment. The software includes an algorithm to calculate the wet bulbtemperature from the weather station transducers. Using the algorithm, a table of water sprayflows required to achieve saturation and overspray is determined. The table contains predictedoperating conditions for each flow stage, including % evaporative cooling and % overspray.When stage flow changes are initiated by the operator, the software signals the fog control panelsto activate the correct combination of pumps and ball valves. The PC also receives feedbackdata from the fog control panels to monitor system flow and pressure, and to indicate systemstatus and alarm signals.

Plots of the last hour of operation for system parameters, including pump flows, pressures, andambient conditions, can be viewed at any time. When the system is operating, data is written andstored to monthly files to provide historical data on spray cooler operation. In addition, monthlydata files are maintained for all operator actions and system events. These historical files can beviewed through commercial spread sheet programs.

The software also includes a module to acquire, analyze and display data transmitted from thedynamic pressure sensor mounted in the compressor casing.

The amount of overspray available will depend on ambient conditions. The water flow toachieve saturation will be lower in rainy or high humidity conditions and more flow will beavailable for overspray. The water flow to achieve saturation will be higher in hot and dryconditions and less flow will be available for overspray. In extreme hot dry conditions all 8 flowstages may be required to lower the compressor inlet temperature to the wet bulb temperature,and no water will be available for overspray.

Predicted Gas Turbine Performance

The design conditions at the site are:• Altitude 870 Feet (265 Meters)• Air Temperature 97 °F (36 °C) Dry Bulb, 74 °F (23 °C) Wet Bulb• Humidity 34%

Base and peak load performance at the design conditions were calculated using performance dataprovided in the OEM manual, which assumes that the compressor is new and clean. The resultsare shown in Table 1. The performance at base load with water injection for NOx control (62.2MW) was used as a basis to evaluate power increases attributed to increased water injection,evaporative cooling, and overspray. Since this gas turbine is neither new or clean, actualperformance was expected to be lower. As such, the predictions serve as a benchmark toevaluate performance enhancement capability.


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In the past Utilicorp operated at water injection rates of about 13 gpm (49.2 liters/min, ~ 0.2water to fuel ratio) during the summer to control NOx. Operation at increased water injectionrates on this unit was studied by EPRI (Ref. 2). In addition, Kern River’s Cogeneration’s OmarHill facility have experience operating at high water injection rates (Ref. 8). Based on this, itwas decided to increase the water injection rate to at least a water to fuel ratio of ~ 0.8. Thepredicted power increase at a water to fuel ratio of ~ 0.8 is 4.6 %, as shown in Table 1.

The spray cooler can be operated at various levels of spray to cool the inlet air by evaporativecooling and, if desired, to inject overspray. Performance calculations were made at base andpeak load for complete saturation (100 % evaporative cooling), and for evaporative cooling withmaximum overspray. In addition, performance with both increased water injection andoverspray was calculated. These results are shown in Table 1. The augmented base load poweris expected to be 11 MW (17.7%) above current levels with increased water injection,evaporative cooling and water overspray.

Table 1 Predicted Gas Turbine Performance at Design Conditions

ConditionsBase

Power(MW)

PowerIncrease

(%)

PeakPower(MW)

PowerIncrease

(%)

No Water Injection 61.5 - 66.9 -Water Injection -- NOx Control (0.2 W/F Ratio) 62.2 0.0% 67.7 0.0 %Increased Water Injection (0.8 W/F Ratio) 65.1 4.6 % 70.8 4.6 %Evaporative Cooled -- NOx Control (0.2 W/F Ratio) 68.5 10.1 % 74.2 9.6 %Evaporative Cooled & Overspray -- (0.2 W/F Ratio) 70.3 11.3 % 76.2 11.3 %Evaporative Cooled -- Water Injection (0.8 W/F Ratio) 71.4 14.8 % 77.3 14.3 %Max Overspray & Water Injection (0.8 W/F Ratio) 73.2 17.7 % 79.2 17.0 %

Demonstration Testing

A demonstration test was conducted on the cooler during the summer of 1996. Testing was firstperformed without spray to establish baseline performance at base and peak load. Spray coolertesting was conducted on the following day. During the spray cooler testing, additional data wasgathered measuring spray droplet distribution, air and water quality and emissions.

High water injection rate tests were conducted on the following day without compressor spray.Tests were run at water to fuel ratios of 0.2, 0.8 and 1.07 (82 gpm, the maximum skid capacity)at base and peak loads.

On the final day, tests were conducted with both high water injection flow and spray. The unitwas started and operated at base load with normal NOx control water injection rates. Aftergathering data, the water injection rate was increased to the skid capacity (~82 gpm [310.4liters/min]). The spray cooler was activated and testing was conducted with 2, 4, 6 and 8 stages.Finally, the unit was ramped to peak load, thus providing data at peak load with maximum waterinjection and all 8 stages of spray activated.


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Demonstration Test Results -- EPRI Spray Cooler Performance

The spray cooler and software operated successfully during the testing. The system achieved100% saturation on all days tested. Figure 7 shows data from a typical day of operation. Thecompressor inlet temperature (Tcit, ~84 °F) was reduced quickly to the wet bulb temperature(Twb, ~70°F) once the proper number of spray stages were activated. Also note thecorresponding increase in power as temperature decreases and overspray is added.

Figure 7 Typical Spray Cooler Performance and Power Gain

The power increase resulting from evaporative cooling was found to be reasonably consistentwith that expected based on the OEM performance curves (Figure 8). About 3.5% in powergain can be expected for every 10 °F (5.6 °C) of cooling.


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Figure 8 Comparison of Measured Spray Cooler Power vs. Predicted Power

Overspray is defined as the excess spray beyond that required to completely saturate the air.Some overspray will be drained away through the LDE and along the inlet surfaces. Theremaining overspray, in the form of small droplets entrained in the air, will pass through the LDEand enter the compressor. Overspray is expressed as the ratio of the overspray water mass to theair flow mass in percentage.

The effect of the overspray is clearly demonstrated in Figure 7. On this day, the compressor inlettemperature (Tcit) was reduced by ~14 °F to the wet bulb temperature (Twb) after four spraystages were placed into service and power increased substantially. When additional stages wereplaced into service no further reduction in Tcit was achieved; however, the power continued toincrease as the overspray evaporated within the first few compressor stages.

The power benefit due to overspray is illustrated in Figure 9. The test results indicate that abouta 5% power gain is achieved for each 1% of overspray. The heat rate benefit due to overspray isillustrated in Figure 10. As can be seen, the measured heat rate was reduced by about 1.8%when all 8 stages were in operation. By contrast, no significant change in heat rate waspredicted.


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Figure 9 Overspray Power Gain

Figure 10 Measured vs. Predicted Heat Rate Change Due to Overspray


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Testing at base load with NOx control water injection was performed several times during theinitial four day test and was repeated in the September tests. These tests confirmed that gasturbine power was about 4% to 7% lower than predicted based on the new and clean OEMperformance curves.

The compressor was not cleaned prior to the demonstration tests and the compressor vanes andblades were observed to be quite dirty. After the compressor was cleaned and tested in lateSeptember 1996 the performance improved to about 2% below that predicted based on the newand clean OEM performance curves.

Droplet Test Results

Droplet measurements were made to determine the level of water droplet agglomeration thatoccurs during spraying, which results in larger droplets than those emitted from the nozzles.Measurements were made at two planes; the first about 2 feet upstream of the LDE and thesecond just upstream of the silencer in one of the pant leg ducts.

Figure 11 compares the droplet distributions from a single nozzle test with those found duringthe demonstration test both upstream and downstream of LDE. This graphic clearlydemonstrates that some of the small droplets emitted from the nozzles agglomerate into largerones. This fact confirms the need for the LDE in this system. Analysis of the downstreamdroplet data confirmed that the LDE effectively removes the larger droplets, as 95% of the masswas in droplets < 35 microns in diameter.


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Figure 11 Comparison of Droplet Distributions -- Single Nozzle vs. Demonstration Test

The data indicated that a higher percentage of overspray flow was removed through the LDE anddrains than was anticipated. Analysis of the data indicated that about 30% of the overspray flowpasses through the LDE and proceeds downstream. This is lower than the 42% that waspredicted prior to the testing and indicates that more water must be sprayed to achieve overspraythan originally anticipated. Based on this, it is projected that 0.18% overspray will occur at thedesign point, somewhat lower than the 0.25% design goal.

Future research and development activities are being planned that will be geared towardidentifying methods to reduce droplet agglomeration.

Dynamic Compressor Pressure Analysis

As discussed above, a high temperature dynamic pressure sensor was installed in the borescopeinspection port in the compressor casing near the 17th stage. This sensor was installed as aprecaution to aid in the identifying the potential onset of compressor rotating stall when highlevels of water overspray are injected. Data from the pressure sensor was analyzed using asignal analysis software package. Figure 12 shows a typical result from this analysis with thesystem operating at high levels of overspray. No significant differences in the frequency


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spectrum or amplitudes were observed when operating at high levels of overspray.

Figure 12 Typical Compressor Spectrum Analysis at High Overspray

This confirmed that application of an overspray system on an MS-7001E does not significantlyaffect the compressor surge margin. However, it should be noted that application of overspraysystems on other gas turbines should be approached with the same caution used here. Surgedetection instrumentation should be employed and used to insure adequate surge margin.

Post Test Spray Cooler Operation

After the demonstration tests were completed, Utilicorp operated the system as needed for theremainder of the summer and early fall of 1996. Additional test data was gathered in earlySeptember. In late September, Utilicorp cleaned the compressor and gathered additional baseload test data.

Utilicorp continued operation during the spring and summer of 1997. Fern and EPRI visited thesite in August 1997 and conducted additional testing. On one of those days, ambient conditionswere near the design point, with temperatures in the mid 90’s and relative humidity around 35 %.The EPRI cooler achieved 25° F of cooling as can be seen in Figure 13 and resulted in a powerincrease of about 11%. To date, the cooler has been operated for about 200 hours.


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Figure 13 EPRI Spray Cooler Operation -- 8/4/97

Water Overspray System Costs

The costs associated with the design and development of this first EPRI spray cooler were paidfor by this tailored collaboration project. These costs included engineering, R&D, bench tests,equipment procurement, demonstration testing and reporting. The demonstration testing verifiedthe design parameters and proved this concept to be a cost effective retrofit to an existing gasturbine inlet. The cost of the entire project was $745,000, or a cost of about $102 per installedKW. This does not include direct costs incurred by Utilicorp United to modify the inlet housing,and complete other site related tasks.

However, equipment and installation costs for future units are expected to be substantially less,as the development costs have already been incurred. Thus, the costs for installation of similarsystems in the future will be substantially less, probably running between $ 50 and $ 75 per KW.

Key design and cost parameters have been included in the EPRI Strategic Capacity and AnalysisDatabase (SCADD) program (Ref. 7), which is available to EPRI members. Costs forinstallation of EPRI spray coolers can be reliably estimated using SCADD.

References


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1� EPRI Report TR-104612, Project 3401-01, Interim Report, "Gas Turbine and CombinedCycle Capacity Enhancement," July 1993.

2� EPRI Report TR-104612, Project 3401-01, Interim Report, "Gas Turbine and CombinedCycle Capacity Enhancement," January 1995.

3� ″Evaporative Cooler Application Guide″, Donaldson Company, Inc.

4� P. E. Nolan and V. Twombly, ″Gas Turbine Performance Improvement Direct MixingEvaporative Cooling System American Atlas Cogeneration Facility Rifle Colorado″, ASME90-GT-368 / Communication, June 1994.

5� EPRI Final Report TR-108057, "Inlet Air Spray Cooler for Gas Turbine PowerAugmentation," May 1997.

6� General Electric publication GER-3116, "The MS-7001E Heavy Duty Gas Turbine," 1979.

7� EPRI Strategic Capacity and Analysis Database Software (SCADD), Version 1.0, EPRI WO3401-01.

8� W. E. Hauhe, G. L. Haube, and C. O. Meyers, “User Experience - Operating a 300 MW BaseLoad Cogeneration Plant with High Water Injection Rates to Control NOx Emissions,”ASME Paper 89-GT-29, June 1989.

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