Notes from Site Visit at Kansas City Power & Light’s Iatan Generation Station

on April 28, 2010

EPA conducted a site visit at Kansas City Power & Light’s Iatan Generation Station (Iatan) 

located in Weston, MO on April 28, 2010 to learn about the operations at the plant, specifically 

the FGD system and the FGD wastewater treatment system. The presentation given by plant 

personnel is included as Attachment 1 to these notes. The FGD system and FGD wastewater 

treatment system process flow diagrams are included as Attachment 2 and 3 to these notes, 

respectively.

These notes describe the information collected during the site visit. Table 1, at the end of these 

notes, identifies the site visit participants.

Plant Overview

• Iatan operates two electric generating units. Units 1 and 2 burn both Powder River 

Basin (PRB) coal. Units 1 and 2 have gross generating capacities of 755 and 920 

MW, respectively and net generating capacities of 705 and 850, respectively. The 

table below contains some general information on the current operation of each 

steam electric generating unit.

Unit

Installation 

Date

Net 

Capacity 

(MW)

Particulate 

Control NOx Control SO2 Control

1 1980 705 Baghouse SCR Wet FGD

2 2010 850 Baghouse SCR Wet FGD

• Iatan receives its coal via train. The plant burns approximately 11,000 tons of 

coal per day. Iatan stores 70 to 75 days worth of coal on site for Unit 1 and 

approximately 30 days worth of coal for Unit 2. The coal pile runoff is collected 

in a holding pond and then discharged to the Missouri River. 

• Iatan operates dry fly ash handling systems on Units 1 and 2. Each unit is 

equipped with a baghouse (fabric filter) to collect the fly ash. Unit 1 was initially 

built with an electrostatic precipitator, but it was replaced with a new fabric filter.

• Iatan also operates a flue gas mercury control system on each unit. The plant 

injects powdered activated carbon (PAC) into the flue gas upstream of the 

baghouses. Therefore, the PAC material, with adhered mercury, and fly ash are 

collected in the baghouses.

• The dry fly ash and PAC material is pneumatically conveyed from the baghouse 

hoppers to the fly ash silo for each unit. The plant has the capability to unload the 

fly ash wet or dry. For wet unloading, the fly ash is conditioned with either 

service water or the FGD brine from the treatment system for dust control. This 

fly ash material is transferred to the onsite landfill for disposal. The plant can also 

unload the fly ash dry for beneficial reuse.
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• Iatan operates dry bottom ash handling on both units. Unit 1 was initially 

installed with a wet bottom ash handling system, where bottom ash was sluiced to 

an ash pond, but the unit was recently retrofitted with a mechanical drag system. 

Unit 2 operates a similar mechanical drag system.

• The mechanical drag systems remove the wet pyrites, bottom ash, and economizer 

ash from the trough directly underneath the boiler furnace. The ash is 

continuously removed and conveyed to a bottom ash bunker.

• The bottom ash is dewatered in the bunker, loaded into trucks, and reused off site 

or trucked to the onsite landfill for disposal. According to the plant, some of the 

bottom ash is marketed for use in cement manufacturing. The water collected in 

the bunker is returned to the bottom ash system.

• Overflow drains from the mechanical drag system are directed to an overflow 

tank and ultimately sent to the Unit 2 cooling tower or clarifiers.

• Iatan operates a once through cooling water system for Unit 1 and a recirculating 

cooling tower system for Unit 2.

Flue Gas Desulfurization System

• Units 1 and 2 both have a wet FGD system to control the sulfur dioxide emissions 

from the plant. Both systems are limestone forced oxidation systems, with a 

spray tower design. A process flow diagram for the FGD system is included in 

Attachment 2.

• Iatan operates a common limestone preparation system for both units. The plant 

uses ball mills and reclaim water, described later in the notes, to generate the 

limestone slurry used in the FGD system. The slurry, which is approximately 30 

percent solids, is pumped through a hydrocylone to classify the slurry. The solids 

that are too large are returned to the ball mills and the remaining solids are 

transferred to the limestone storage tank. The limestone slurry is then pumped to 

the reaction tank of the FGD system. 

• Both FGD systems have five spray levels, but the plant typically only operates 

three or four of the spray levels at a time. The plant pumps the limestone/gypsum 

slurry in the reaction tank up to the various spray levels in the absorber which 

flows counter-current to the flue gas.

• The limestone reacts with the sulfur dioxide to generate calcium sulfite and the 

calcium sulfite is oxidized to calcium sulfate (i.e., gypsum) in the reaction tank. 

• Iatan does not use any additives (e.g., organic acids) in the FGD system.
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• The FGD system has a maximum chlorides level of 12,000 ppm. The system 

operates with a chlorides level of 4,000 to 5,000 ppm. The system operates at a 

low chlorides concentration because of the low chlorine content in the PRB coal.

• The solids in the FGD system range from 16 to 18 percent solids. When the 

solids concentration reaches 18 percent, the plant blows down from the system. 

The FGD blowdown is transferred to a set of hydrocyclones which separates the 

gypsum from the water.

• The underflow from the hydrocyclones is transferred to the filter feed tank. From 

the filter feed tank, the gypsum is pumped to the vacuum rotary drum filters, 

which dewater the gypsum. Iatan does not have the capability to wash the 

gypsum. The gypsum is dewatered to a moisture content of approximately 20 

percent. The plant does not market the gypsum, so it is trucked to the onsite 

landfill. Iatan stated that they are still trying to market the gypsum, so they try to 

separate the gypsum from the fly ash in the landfill. The filtrate from the rotary 

drum filters is transferred to the reclaim water tank.

• The overflow from the hydrocyclones is transferred to the reclaim water tank. 

The reclaim water tank also receives the filtrate from the rotary drum filters, mist 

eliminator wash, sump water from the limestone preparation, FGD absorber, and 

bottom ash storage areas, and cooling tower blowdown.

FGD Wastewater Treatment

• Diagrams of the FGD wastewater treatment system are included in Attachment 3.

• Most of the water in the reclaim water tanks is reused in the FGD system. 

However, a bleed stream from the reclaim tank is transferred to the FGD 

wastewater treatment system.

• From the reclaim tanks, the wastewater is either directed to the ZLD wastewater 

storage tank or the ZLD backup holding tank. From the wastewater storage tank, 

the wastewater enters the metal removal clarifier. Iatan adds a coagulant and 

polyelectrolyte to the clarifier. The underflow from the clarifier is transferred to a 

thickener. The thickener also receives the raw water clarifier underflow.

• The underflow from the thickener is mixed with a polymer and dewatered using a 

belt filter press. The solid waste is trucked to the onsite landfill for disposal. The 

overflow from the thickener is transferred to the raw water clarifier.

• The overflow from the metal removal clarifier is transferred to the evaporator feed 

tank where the plant adds sulfuric acid and an antiscalant. The plant lowers the 

pH from 5.5 to 5.2 S.U.

• From the evaporator feed tank, the wastewater is pumped through a heat 

exchanger, where the process distillate heats the FGD wastewater, and then to the 
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deaerators. The deaerators allow the noncondensibles such as carbon dioxide and 

oxygen to vent to the atmosphere.

• Iatan operates two trains of the evaporation process. At the time of the site visit, 

Iatan was making process modifications on Train A to improve consistency in 

performance. After modifications were made to that system, the plant planned to 

make similar modifications for Train B.

• The wastewater from the deaerators is then fed to the sump of the falling-film 

brine concentrator. Brine from the sump is pumped to the top of the brine 

concentrator and enters the heat transfer tubes. Iatan also adds caustic, an 

antifoaming agent, and seeded calcium sulfate to the brine as it is pumped to the 

top of the brine concentrator. While falling down the heat transfer tubes, part of 

the solution is vaporized and then compressed and introduced to the shell side of 

the brine concentrator (i.e., the outside of the tubes). The temperature difference 

between the compressed vapor and the brine solution causes the compressed 

vapor to transfer heat to the brine solution, which flashes to a vapor. As heat is 

transferred to the brine, the compressed vapor cools and condenses as distilled 

water.

• The distillate from the brine concentrator is collected and transferred to a distillate 

tank. Within this tank, some additional steam vapor is returned to the shell side of 

the brine concentrator. The remaining distillate is used to heat the incoming FGD 

wastewater and is then sent to the clean ZLD sump. 

• The concentrated brine slurry from the brine concentrator tubes falls into the 

sump and is recycled with the feed (i.e., FGD wastewater) back to the top of the 

brine concentrator, while a small amount is continuously withdrawn from the 

sump and transferred to a set of hydrocyclones. To prevent scaling within the 

brine concentrator as a result of the gypsum present in the FGD wastewater, the 

brine concentrator is seeded with calcium sulfate. The calcium salts preferentially 

precipitate onto the seed crystals instead of the tube surfaces of the brine 

concentrator. The hydrocyclones recover the calcium sulfate seed crystals in the 

underflow and recycle the seed to the recirculation stream entering the top of the 

brine concentrator. The overflow from the hydrocyclones is the concentrate that is 

transferred to the brine blowdown tank.

• From the brine blowdown tank, the brine is transferred to the brine storage tank. 

The plant uses the brine as a source for conditioning the fly ash prior to disposal 

in the landfill.

• As described previously, the distillate from the brine concentrator is collected in 

the clean ZLD sump. This sump water is then transferred to the raw water 

clarifiers and reused in the plant.

• The evaporation system concentrates the brine by a factor of seven.
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• The evaporation system was designed for a TDS concentration of 15,000 ppm; 

however, at the time of the visit, the TDS concentration was 70,000 ppm, which 

was causing issues with the evaporation system. The plant had been cycling the 

water in the FGD system to raise the chlorides level, but because the plant uses 

PRB coal, which generally has lower chlorides, the additional recirculation was 

causing a much higher build up of TDS.

• The system began operating in March 2009 and was not operating continuously at 

the time of the visit.

Ash Pond

• Iatan has an ash pond that was used for handling the bottom ash sluice water and 

depositing fly ash that was not marketed. However, since the conversion to the 

dry bottom ash system and the installation of the onsite landfill, the pond has not 

received any additional ash waste. 

• The ash pond is not lined and is approximately 15 to 20 feet deep, based on the 

original construction. The pond consists of two cells operated in series. There is 

currently no discharge from the pond.

• Iatan is looking into dewatering the solids in the pond and marketing the material 

for reuse.

Landfill

• Iatan operates an onsite landfill, which began operation in January 2009. The 

landfill has four stages and the plant is currently filling Stage 1. The landfill has a 

two foot clay liner, 60 mm HDPE liner, and 12 inches of sand.

• The plant collects landfill leachate and runoff in a collection ponds. The leachate 

is used for dust suppression control on the landfill. The plant has an emergency 

discharge outfall from the collection pond. 

• Iatan has eight groundwater monitoring wells around the landfill. All of the wells

are considered by the Missouri Department of Natural Resources (MDNR) to be

downgradient of the landfill. 

• Iatan conducted two years of groundwater monitoring prior to putting any solids 

in the landfill.
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Table 1. Site Visit Attendees

Name Organization (Representing) Telephone E-mail

Gary Brown KCPL 816-386-5225 gary.brown@kcpl.com

Paul Ling KCPL 816-556-2899 paul.ling@kcpl.com

Tom Mackin KCPL 816-556-2957 tom.mackin@kcpl.com

Nick Voris KCPL 816-386-5225 nick.voris@kcpl.com

Donna Hill UWAG 205-257-5234 dbhill@southernco.com

Ron Jordan EPA/Office of Water 202-566-1003 jordan.ronald@epa.gov

Bill Swietlik EPA/Office of Water 202-566-1129 swietlik.william@epa.gov

Deb Bartram ERG (Contractor to EPA) 703-633-1669 deborah.bartram@erg.com

TJ Finseth ERG (Contractor to EPA) 703-633-1698 thomas.finseth@erg.com