Final Notes from Site Visit at WVPA’s Wab ash River Power Station on February 25, 2009

EPA conducted a site visit at the Wabash Valle y Power Association’s (WVPA’s) Wabash River Power Station (Wabash) located in Terre Haut e, IN on Wednesday, Febr uary 25, 2009 to learn about the operations at the plant, specifically the integrated gasificati on combined cycle (IGCC) unit. Table 1, located at the end of these not es, identifies the site visit participants.

Attachment 1 contains an overall water balance di agram for the plant. The presentation that the WVPA personnel gave during the site visit is provided as Attachment 2 to these notes.

Plant Overview

 PSI Energy originally brought Unit 1 on line in the 1950s as a standard coal-fired combustion generating unit, and converte d (“repowered”) Unit 1 into an IGCC system in 1994. At the time of the site visit, Wabash Valley Power Authority (WVPA) owned the combined cycle portion of Unit 1 (i.e., the gas turbine, heat recovery steam generator (HRSG), and st eam turbine, but not the gasification system). The gasification system has been owned by several entities since 1994 and is currently owned by SG Solutions (SGS).

 The IGCC system began as a demonstr ation project, but has been operated commercially since 1996. The gross capaci ty of Unit 1 is 296 MW (192 MW gas turbine, 104 MW steam turbine) . The net capacity is 262 MW.

 The gasification plant is located next to the Wabash River plant and comprises approximately 20 acres.

 The steam turbine associated with the combined cycle portion of the unit is located inside the Duke Energy plant.

 Cooling water intake and cooling water di scharge for the combined cycle unit are handled by Duke Energy.

Unit 1 IGCC Operations

 The gasification technology used at Waba sh is the Global Energy E-GASTM coal gasification process.

 The current plant configurat ion consists of a single train, with one two-stage gasifier supplying one combustion turbine.

 During the demonstration phase of the unit (1995-1999), 2,500 tons/days bituminous coal with up to 3.5% sulfur was burned. Since August 2000, 2,000 tons/day petroleum coke (pet coke) with up to 6% sulfur is burned. The pet coke is a cheaper fuel, but generates more as h. The plant holds approximately 70 days of pet coke on site.Page 2

 Pet coke is received via rail and slurried in the rod mill. It is then combined with 95% pure oxygen in slurry mixers and inject ed into the first stage of the gasifier, which operates at 2,600 ο F and 400 psi.

 Ash is transformed to a molten form and flows to the quench station as a slag/water slurry. This slurry flows into a dewatering bin equipped with an inclined plate separator. The slag settles out in the bin and is re turned to the slurry preparation area, while water overflows to a storage tank and is returned to the gasifier quench in a closed loop system.

 Dewatered slag is loaded into a truck or rail car for transport to market or its storage site. The slag can be temporarily st ored on site at a storage slab located adjacent to the Slag Hopper Building. Add itionally, the slag can be transferred to a location in Clinton, Indiana where it is de posited in a prepared cell in a qualified manner as per Indiana Department of Environmental Management guidelines.

 Pet coke slag is finer than coal slag. Plant personnel have experimented with the amount of oxygen to add stating that a re ducing environment converts the ash to a glassy, “encapsulated” substance. Personnel also noted that this substance passes leaching tests and none of the slag is stockpiled on site.

 The syngas flows to the second stage of th e gasifier, where additional slurry is injected. Syngas leaving the gasifier flows to the high temperature heat recovery unit (HTHRU) to produce high-pressure sa turated steam. The syngas is cooled

from 600 ◦ C to 100 ◦ C, and the resulting condensate is referred to as sour water. Approximately 1,500 pounds of steam are tran sferred to the heat recovery steam generator (HRSG).

 After cooling in the HTHRU, particulates (“char”) are filte red from the syngas and recycled to the first stage of the gasifi er where the carbon in the particulates is converted into more syngas. Plant pers onnel stated that 99.9% of the carbon is converted to syngas.

 The syngas is cooled and scrubbed with sour water to remove chlorides. The syngas passes through a catalyst that hydrolyzes carbonyl sulfide (COS) to hydrogen sulfide (H 2 S). The syngas is then processed through methyldiethanolamine (MDEA) based absorber/stripper columns, where the acid gas is removed and the clean syngas (approximately 35 ◦ C) is transferred to the combustion turbine to generate additional power.

 The acid gas stream is transferred to a sulf ur recovery process where sulfur that is 99.999% pure is recovered and marketed. Pl ant personnel stated that one rail car

is filled with this sulf ur by-product every 22 hours.

 Sour water collects in the low temperat ure heat recovery unit (LTHRU) holding tank. Approximately 60% of the sour wate r is recycled back to the rod mill as slurry water. The remaining sour water is transferred to the wastewater treatment
system.Page 3

Unit 1 Wastewater Generation and Treatment

 Sour water consists of the combined condensate and scrubber blowdown streams,

as well as the sour water return from the sulfur recovery unit.

 The sour water is sent to a CO 2 stripper, where steam is used to remove carbon

dioxide from the water. Some of this stri pped water is then recycled to the coal slurry process. The remainder is sent to a second steam stripper to remove the ammonia present in the water.

 The cleaned water leaving the ammonia st ripper is transferred to a mechanical vapor compression system, consisting of an evaporator (referred to by the plant as the zero liquid discharge (ZLD) system). The concentrated brine from the ZLD process is sent to a rotary drum dryer to remove the water from the salts. Plant personnel stated that the ro tary drum dryer needs increased maintenance due to the corrosive salts being handled.

 Salts (which are contaminated with seleni um and arsenic) are transferred offsite as hazardous waste one to two times per w eek. The material is currently disposed with Veolia, who makes a stabilized cement product.

 The distillate from the ZLD is the portion of the wastewater that is discharged from the plant. Plant personnel stated that the ZLD system was incorporated into the process after the initial start up; therefore, the pr ocess was not designed to reuse the distillate. Additionally, the distil late could not be used in the combined cycle process because it was owned by Duke Energy.

 Plant personnel stated that they do sometimes use the di stillate for coal slurry make-up water, but because the distillate is at a high temperature, it has to be cooled in sumps before it is re turned to the slurry process.

 In addition to the distillate from the ZLD system, the following wastewaters are

also associated with the operation of the IGCC unit:

 Air separation unit blowdown;

 Slag handling wastewater;

 Blowdown from the heat recovery steam generator;

 Petroleum coke pile runoff pond effluent;

 Raw water filtration backwash;

 Demineralizer system reject; and

 Cooling tower blowdown.

 These waste streams are transferred to the plant’s wastewater treatment pond. The water from this pond is transferred via internal Outfall 102 to the Duke Energy ash pond, which discharges to the Wabash River.

 Although WVPA is required to get a new permit because of the purchase of the combustion turbine and combined cycle por tions of the plant, Wabash River isPage 4

still currently transferring the wa stewater to the Duke Energy ash pond.

 Plant personnel stated that when they stop transferring the water to the Duke Energy ash pond, the wastewater from th e wastewater holding pond will be transferred to the plant’s storm water pond and then discharged to Wabash River

via the new Outfall 001.

 Wabash River expects to begin dischargi ng from the new outfall in late fall 2009.Page 5Table 1. Site Visit AttendeesNameOrganization (Representing)TelephoneE-mailTerry Hogan WVPA 317-696-5666 T_hogan@wvpa.comJarod KlaasWVPA317-481-2838 J_klaas@wvpa.comJeff BellWVPA317-481-2920 J_bell@wvpa.comRichard PayonkConocoPhillips812-535-6062 Richard.j.payonk@conocophillips.comMary HendersonSG Solutions (SGS)/ConocoPhillips812-535-6075 M_henderson@sgswabash.comDonna HillUWAG205-257-5234 dbhill@southernco.comSean Ramach US EPA Region 5 312-886-5284 Ramach.sean@Epa.govRon Jordan EPA/Office of Water 202-566-1003 jordan.ronald@epa.govDeb Bartram ERG (Contractor to EPA) 703-633-1669 deborah.bartram@erg.comAttachment 1 WVPA Wabash Water Balance DiagramAttachment 2

WVPA Wabash Presentation[The remainder of the WVPA Wabash presentation is held as Confidential Business Information]