Draft Notes from Site Visit at American Electric Power’s Cardinal Steam Electric Plant on February 2 , 2010

EPA conducted a site visit at American Electric Power’s Cardinal Steam Electric Plant (Cardinal) located in Brilliant

, OH on Tuesday

, February 2 , 20 10 to learn about the operations at the plant

, including the operation of the flue gas desulfurization ( FGD ) wastewater treatment system

. Table 1 identifies the site visit participants. The presentation Cardinal gave during the site visit is included as A t tach ment 1

.

Plant Overview

**•** Cardinal operates three coal

- fired electric generating units

. American Electric Power ( AEP ) owns U nit 1 and operates th e facility. Buckeye Power owns U nits 2 and 3

. The table below contains some general information on the curre nt operation of each steam electric generating unit.

Unit Installation Date Gross Net Capacity

(MW) Particulate Control NOx Control SO 2 Control 1 1967 600 ESP (Electrostatic precipitator) (cold

side) SCR (2001) Wet FGD (March 2008)

2 1967 600 ESP (cold

- side) SCR (2001) Wet FGD (December 2007) 3 1977 630 ESP (hot

- side) SC R (2001) Wet FGD (Planned for 2012 )

**•** Cardinal burns 4.5 million tons of coal annually. Units 1 and 2 burn only bitumino us coal . Unit 3 burns 80% low sulfur coal and 20% powder river ba sin ( PRB ) coal

. After Cardinal completes the FGD scrubber on U nit 3 , the plant plans

on switching coals to burn a coal with a higher sulfur c on tent ( or whatever coal is cheapest )

. The FGD systems on U nit 1 and 2 were originally designed for a coal with 7.5 lbs sulfur dioxide ( SO 2 ) per mmbtu. However, starting in 2001 during NO x season , the sulfur in the coal was reduced to 2.5 lbs SO 2 per mmbtu to reduce sulfur trioxide ( SO 3 ) formation.

**•** Cardinal receives c oal for U nits 1 and 2 via truck ; whereas, coal fo r U nit 3 is received via barge. The plant stores a pproximately 30

- 60 day s’ supply of coal on site.

**•** Units 1 and 2 use the following air pollution control technologies in the following order: low NOx burners, SCR system, ESP, and FGD absorber. Unit 3 operat es the same order of air pollution control technologies ; however, the FGD absorber has not yet been installed.

**•** Cardinal does not regenerate the SCR catalysts on site.Draft Cardinal Site Visit Notes **•** Cardinal operates an on

- site landfill that receives FGD gypsum. The landfill has a l eachate collection system. The leachate collected from the system is has an internal outfall (O utfall 602) and is ultimately discharged via final O utfall 019. Cardinal is required to monitor at internal O utfall 602 for flow, dissolved solids, fluoride, bo ron, mercury, and selenium.

Flue Gas Desulfurization System

**•** U nits 1 and 2 both hav e wet FGD systems

. Cardinal is in the process of adding a n FGD system to U nit 3

. The FGD system for U nit 3 will be designed similarly to Units 1 and 2; h owever, Cardinal is n ot installing a stack for Unit 3

. Instead the flue gas will be inserted into the center of the cooling tower. This will lead to better dispersion, additional droplet removal within the cooling tower, and is cheaper th a n building a stack. Cardinal stat es that a stack can cost up to 30 million dollars to install. Although this technology is commonly used in Europe, Cardinal is the first US plant to build one

.

**•** Units 1 and 2 both have 95% SO 2 removal capability using high sulfur coal (7.5 lb S/mmbtu). Ad ditionally, b oth units have a SO 3 mitigation system including Trona injection

.

**•** The FGD systems are wet limestone forced oxidation jet bubbling reactors (JBR) designed by Bla c k and Veatch

. Service water is used to cool the flue gas from 300°F to 126°F. Onc e cooled

, the flue gas is injected into the bottom of the FGD absorber. Oxygen is supplied to the reaction by aeration. T he SO 2 reacts with limestone (CaCO 3 ) and oxygen to form gypsum (calcium sulfate), water, and carbon dioxide ( CO 2 )

. The pH in the absorb er is maintained at 4.8 S.U . Limestone is more easily dissolved at a lower pH, so with this low pH

, the plant does not have to grind the limestone as much as other plants. Although SO 2 dissolves better with a higher pH, the low pH does not impact SO 2 absorption because the system has a high degree of aeration

.

**•** Cardinal receives l imestone at the plant via barge. Cardinal operates an on

- site ball mill to crush the limestone . The limestone slurry formed in this process is sent to a hydro cy clone . The underflow from the hydrocyclone goes back to the ball mill. The overflow typically contains 30% solids by weight and is sprayed into the flue gas in the spray tower or pumped into the JBR.

**•** When the solid s concentration in the absorber reaches approximately 20 perc ent and the chloride s concentration is around 4 ,000 to 5,000 ppm, C ardinal blows down from the FGD system. The system is designed to have a limit of 12,000 ppm of chlorides ; h owever, Cardinal has found that the FGD scrubber system operates best if the chlo ride s concentration does not g o above 4 ,000

- 5,000 ppm.

**•** Blowdown from the FGD scrubber is not continuous and typically occurs for 12 hours a day. The number of times blowdown o ccurs and the length of time each blowdown lasts is dependent on the operator and the amount of electricity generated. Blowdown from the FGD scrubber is sent to a set of primary hydrocyclones

.Draft Cardinal Site Visit Notes **•** T h e underflow from the primary hydrocyclones is transferred to vacuum belt filters to dewater the gypsum. Cardinal washings the gypsum as it is applied to the vacuum belt filters to reduce the chlorides in the gypsum. Filtrate from the vacuum belt filters is sent to the reclaim tank. Wastewater in the reclaim tank is either recycled back to the JBR or sent to the wastewater treatment system.

**•** T he dewatered g ypsum contains 95% solids and less than 10 ppm of chlorides. The gypsum must have less than 10% moisture for Cardinal to be able to sell it to wallboard manufacturers. Cardinal sells approximately 50% of the gypsum to Serpentine. All gypsum that is not sold is transported to an on

- site landfill.

**•** The overflow from the primary hydrocyclone s is transferred to the wastewater treatment system . This waste stream contains approximately two percent solids. Cardinal also blows down from the reclaim tank

.

**•** Cardinal only has one hydrocyclone . Personnel state that the plant only needs one hydrocyclone because the hydrocyclone is sized correctly.

FGD Wastewater Treatment System

**•** A process flow diagram for the FGD wastewater treatment system at Cardinal is i ncluded as A ttach ment 2

.

**•** Cardinal began sending FGD waste water to the wastewater treatment plant in January 2008. According to plant personnel, i t took two to three weeks for the
treatment system to fill up with water

.

**•** The hydrocyclone overflow and reclaim water are both transferred to the FGD wastewater treatment system. The plant has a sample point for the combination of the two streams before they enter the wastewater treatment system , but there is
not a sample point for the individual streams.

**•** The FGD w as tewater is first combined in two equili zation (EQ) tank s . The EQ tanks main purpose is to help the system maintain a steady flow rate. Mainly

, the EQ tanks contain hydrocyclone overflow and wastewater from the reclaim water tank. Sumps from the wastewat er treatment building are also transferred to the EQ tank. If the e ffluent from the FGD wastewater treatment system does not meet the specifications for discharge, the plant can pump the effluent back t o the EQ tank.

**•** The wastewater from the two EQ tanks i s combined and then split to enter two the two trains of the FGD wastewater treatment system operating in parallel. The wastewater first enters the desaturation tank s

. Cardinal adds l ime to desaturation tanks to maintain a pH of 9.0 S.U . Cardinal personne l state d that lime is not added to target any specific metals.

**•** The wastewater travels from each desaturation tanks to a primary clarifier (i.e., desaturation tank A flows into primary clarifier A and desaturation tank B flows into primary clarifier B). Th e sludge from each primary clarifier is pumped to the sludge holding tank s

.Draft Cardinal Site Visit Notes **•** The overflow from each primary clarifier is transferred to the coagulant mix tank s

. Cardinal adds f erric chloride and sulfuric acid to each of the coagulant mix tank s

. The s ulfuri c acid is added to lower the pH to 8.0

- 8.3 S.U

. Cardinal determined that ferric chloride works better at this pH set point

. Cardinal is also plan ning to add organosulfide to each mix tank by December 2010. Cardinal is adding organosulfide to specifically t arget mercury removal. The organosulfide storage tank has not been built yet.

**•** After the coagulant mix tank s , the wastewater is transferred to the secondary clarifier s, where Cardinal adds anionic polymer. The secondary clarifiers are solids contact clarifi ers. The sludge from each secondary clarifier is either recycled back to the desaturation tank to act as seed crystals or sent to one of the sludge holding tanks.

**•** The sludge in each of the two sludge holding tanks is dewatered using one of four filter pres ses. The filtrate from the dewatering process is sent to the filtrate equalization tank and returned to the secondary clarifiers. Cardinal personnel
state d that the filtrate goes to the secondary clarifier rather than back to the EQ tank because the wastew ater has already been processed so there is no need for it to go through the entire process all over again.

**•** The dewatered solids from the filter presses are trucked to the XXXX [QUESTION FOR CARDINAL: How does the plant dispose of the wastewater
treatment solids?]

**•** The overflow from the secondary clarif i er s is transferred to the effluent storage tank s . Although Cardinal had planned to install gravity filters after the effluent tanks as shown in the process flow diagram for the wastewater treatment sys tem, th ey decided not to add these units. C ardinal personnel state that the floc is too fine for the gravity filters to funct ion efficiently. Furthermore, they stated that it would be impossible to add ultrafiltration or microfiltration at the end of the
process because of scaling problems.

**•** Cardinal has limits for the discharge of effluent from the FGD wastewater treatment system ( internal outfall 601 ) for pH and suspended solids. Additionally,
t he plant must monitor the following pollutants: flow, temperature, sp ecific conductance, dissolved solids, alkalinity, chlorides, fluorides, sulfate, arsenic, barium, boron, cadmium, chromium, copper, iron, lead, mercury, nickel, selenium, and zinc.

**•** There is a sample point for the effluent where the plant does compliance

m onitoring. Cardinal takes 24

- hour composite samples at the location

. The flow rate of the effluent is around 645

- 700 gpm ; however, t h e effluent is not necessarily continuous over the entire day and depends largely on the amount of wastewater recirculating through the system. FGD w astewater still flows through the sample point even when wastewater is being recirculated in the system

.

**•** Effluent from the FGD wastewater treatment system is discharged to the river at the same location where once

- through cooling w ater is discharged at final outfallDraft Cardinal Site Visit Notes 001

. Twenty feet below the surface of the river there is a 20

- foot long header which disperses the release of the treated wastewater.Draft Cardinal Site Visit Notes Table 1 . Site Visit Attendees

Name Organization (Representing) Telephone E

- mail

T om Hart AEPSC 614

- 716

- 3260 tomlhart@AEP.com
Deanna King AEPSC 614

- 716

- 1234 djking@aep.com

JR Holland AEP

– Cardinal 740

- 598

- 6806 JRholland@aep.com

Bernie Lombard AEP

- Car dinal 740

- 598

- 6514 BLombard@AEP.com

Tom Kaufmann AEP

– Cardinal 740

- 598

- 6511 Tdkaufmann@aep.com

Donna Hill Southern Company, UWAG 205

- 257

- 5234 dbhill@southernco.com

J osh Hall EPA 202

- 566

- 1002 hall.josh@epa.gov

TJ Finseth Eastern Research Group 703

- 633

- 1698 thomas.finseth@erg.com
Becky Schwantes Eastern Research Group 703

- 633

- 1715 becky.schwantes@erg.com