Draft Notes from Site Visit at TECO Energy’s Polk Power Station on October 8, 2009

EPA conducted a site visit at TECO Energy’s Polk Power Station (Polk) located in South Mulberry, FL on Thursday, October 8, 2009 to learn about the operations at the plant

, specifically the integrated gasification combined cycle (IGCC) unit

. Table 1, located at the end

of this memorandum , identifies the site visit participants. The presentation that the Polk personnel gave during the site visit is provided as Attachment 1 to this memorandum.

This memorandum describes the information collected during the site visit and the pre

- site visit phone call, which was held on October 2, 2009.

Plant Overview

TECO personnel provided an overview of operations for Tampa Electric Genera tion, as shown in Attachment 1. This memorandum focuses on operations at the Polk Power Station. Attachment 2 contains an overall water balance diagram for the plant.

**•** Polk currently operates five electric generating units at the power plant, with a

gross generating capacity of 920 MW. The table below contains some general information for the five generating units.

Unit Installation

Date Gross Capacity (MW) Unit Type Fuel Type

1 1996 320 (250 MW net) Integrated Gasification Combined Cycle (IGCC)

– base load Syngas generated from coal and petroleum

coke/distillate oil

2 2000 150 Simple cycle combustion

turbine Natural gas/distillate oil

3 2002 150 Simple cycle combustion

turbine Natural gas/distillate oil

4 2007 150 Simple cycle combustion

turbine Natu ral gas

5 2007 150 Simple cycle combustion

turbine Natural gas

**•** The Polk plant comprises over 4,000 acres (of which 750 acres comprises the cooling pond) and currently employs 80 people.

**•** Cooling water for the plant is supplied by a 750

- acre unlined cool ing pond. Cooling water recirculates from the process to the pond. Due to evaporation, well water is used to makeup water to the cooling pond. Periodically, water from the cooling water is discharged to the Little Payne Creek, due to dissolved solids th at build up in the pond or due to extreme rainfall events. The cooling pond also receives treated water from the slag runoff retention basin, the oily water collection and treatment system, and the storm water collection system.

**•** The Polk site was previou sly mined for phosphate.Page 2

Unit 1 IGCC Operations

**•** The gasification technology used at Polk was originally developed by Texaco and is now owned by GE.

**•** The current plant configuration consists of a single train, with one gasifier supplying one combustion tu rbine.

**•** Saturated steam created in the gasifier is pumped to the Heat Recovery Steam Generation (HRSG) unit and used to power a steam turbine.

**•** Syngas from the gasifier is processed and cleaned before being used to power the

combustion turbine. Diluent nit rogen is combusted with the syngas to reduce NOx

formation.

**•** The plant uses 2,200 tons per day of fuel. Current fuel is a blend of 30% coal and 70% petroleum coke. The station has experimented with use of several fuel blends comprised of various coals and petroleum coke, and has also included various biomass blends as well. Low rank fuels, which can be used in slurry fed gasifiers, lower the overall efficiency of the unit.

**•** Coal is received via covered truck, bottom dumped onto a conveyor, and stored in one of two 5,000

- ton silos. The plant can hold approximately 5 days of fuel on site. Approximately 95 trucks per day are received at full capacity.

**•** The plant stores slag generated in the gasifier in an outdoor lined pile. The slag is

either marketed of fsite (in the cement industry or used as a fuel component at Tampa Electric’s Big Bend Station) or it is fed with the coal to the slurry preparation rod mill. Polk has also periodically transferred slag to an off

- site landfill for disposal.

**•** Runoff from t he slag pile is collected in two runoff basins, which are designed to

hold the volume for a 100

- year 24

- hour storm event. The runoff is sampled 2 times per year. Leachate from the runoff basins is held in a leachate pond, prior to filtration and discharge to the cooling pond. The slag pile bottom liner is 60 ml and top liner is 80 ml. [NOTE TO POLK: Please provide the list of pollutants for which the slag pile runoff and/or leachate is analyzed. Please provide a copy of the most recent analyses completed .]

**•** Coal and petroleum coke is fed to the rod mill to be ground and mixed with water and recycled char (slag) from the IGCC process to create a slurry. The slurry is then pumped to the gasifier where it is mixed with oxygen from the air separatio n plant to create a syngas.

**•** The gasification process operates between 2,300 **°** F and 2,700 **°** F. This process creates syngas, slag, and flyash.Page 3

**•** The syngas is about 30% hydrogen, 30% carbon monoxide, XX % carbon dioxide,

14

- 15% nitrogen, and about 1% sulfur. [NOTE TO POLK: Please provide percent of carbon dioxide in the syngas.]

**•** The slag and about 50% of the flyash generated collects in a water pool located at the bottom of the gasification unit. The wet slag and flyash moves through the slag crusher onto th e slag drag conveyor where it is deposited onto a screen. The coarse material captured by the screen is collected and sold to the cement industry. Water and fines passing through the screen are considered “black water” which is pumped to the settler feed tank.

**•** Remaining flyash and syngas flow through a convective syngas cooler to a water scrubber (referred to as the “syngas scrubbers”) for the removal of particulates and hydrochloric acid (HCl) from the syngas. The scrubber blowdown, also

referred to as “black water,” is pumped to the settler feed tank at about 400 gpm.

**•** Syngas is further cleaned in the carbonyl sulfide (COS) hydrolysis unit, which converts the COS to hydrogen sulfide (H 2 S). Following this unit, the gas is cooled through three small heat exchangers and sent to the acid gas removal system.

**•** In the acid gas removal system, the syngas is scrubbed with methyl diethanol amine (MDEA), which captures the H 2 S in the syngas. The cleaned syngas is then heated, filtered with a 10

- micron cartridge fi lter, and sent to the combustor.

**•** The MDEA and H 2 S solution from the bottom of the scrubber is transferred to the MDEA stripper, which uses steam to release the H 2 S from the MDEA. The H 2 S and other noncondensibles gases are transferred to the sulfuric aci d plant. The MDEA is collected, cooled, and reused in the scrubber.

**•** The sulfuric acid plant produces about 200 tons per day of 93

- 98% acid.

Unit 1 W astewater Treatment

**•** D iagram s of the wastewater flow and management associated with Unit 1 are include d as Attachment 3.

**•** Black water that collects in the settler feed tank is pumped to one of two gravity settlers, where a flocculant and coagulant are added. The overflow from the tanks is referred to as grey water and is stored in a conical tank. Most o f the grey water is recycled to the syngas scrubbers, as shown in Attachment 2. Approximately 100 gpm is transferred to the brine concentration system.

**•** The underflow from the gravity settlers is recycled directly to the slurry preparation step.

**•** Grey wat er transferred to the brine concentrator is sent through a vapor compression cycle to evaporate the majority of the water. The brine concentrate, which contains about 30,000

- 40,000 ppm chlorides, is transferred to a second evaporation step followed by a cr ystallizer to reclaim solid ammonium chloridePage 4

from the waste stream. The solids (16% moisture) are disposed off site. Approximately 15 tons of solids are produced each week.

**•** In the past, Polk experienced exceedances of the NPDES permit limit on selenium

i n discharges from the cooling water pond. Several forms of selenium were measured (Se

- 4, Se

- 6, and selenocyante). The source of the selenium responsible for the permit exceedances was found to be the neutralized weak acid return from the sulfuric acid plan t. Selenocyanate has also been measured at low levels in leachate from the slag pile.

**•** Condensate from the brine concentrator is reused for pump seals and instrument tap flushes. It contains less than 100 ppm chlorides.

Simple Cycle Unit Operations (Units 2 through 5)

**•** Units 2 and 3 are fueled by oil and natural gas, while units 4 and 5 are fueled only by natural gas.

**•** The air compressors are cleaned with a water/detergent solution every other year. The gas turbines are cleaned about every three years.

**•** Mi scellaneous wastewaters, including contaminated precipitation, pump and seal leakage, and maintenance are managed in the oily water system.

**•** Water in the oily water system is treated through an API oil/water separator, followed by a dissolved air flotation (DAF) unit, equalization basin where caustic is added to adjust the pH from 5 to XX , and sand filter. The water, including filter backwash, is then discharged to the cooling pond. [QUESTION FOR POLK: What is the final adjusted pH in the equalization tan k?]Pa ge 5

Table 1. Site Visit Attendees

Name Organization (Representing) Telephone E

- mail

Kevin Young TECO Energy 813

- 228

- 4232 kayoung@tecoenergy.com

Stanley Kroh TECO Energy xxx

- xxx

- xxxx smkroh@tecoenergy.com

Paul Carpinone TECO Energy 813

- 228

- 4858 plca rpinone@tecoenergy.com

Mike Perkins TECO Energy 813

- 228

- 1111 mrperkins@tecoenergy.com

Temi Linjewile TECO Energy 813

- 376

- 8823 tmlinjewile@tecoenergy.com

James P. Moore, Jr. TECO Energy 813

- 228

- 1111 jpmoore@tecoenergy.com

Donna Hill UWAG 205

- 257

- 5234 db hill@southernco.com

Ron Jordan EPA/Office of Water 202

- 566

- 1003 jordan.ronald@epa.gov

Deb Bartram ERG (Contractor to EPA) 703

- 633

- 1669 deborah.bartram@erg.com

[ NOTE TO POLK : Please fill in missing contact information.]