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WASATCH ENERGY SYSTEMS UTLIZES RETROFITTING TO UPGRADE POLLUTION CONTROL SYSTEM
--AirPol, Inc. of Parsippany, N.J. helps Wasatch Energy meet and exceed new environmental regulations.
Wasatch Energy Systems (WES) owns and operates the Davis County Energy Recovery Facility (DCERF), a mass burn municipal solid waste incinerator, and the Davis County Landfill, both located in Davis County, Utah. WES is a Special Service district providing integrated solid waste disposal services to more than 200,000 residents in 15 cities and two counties.
In October 1999 WES solicited proposals from qualified contractors for new air pollution control equipment as required to meet proposed federal regulations. In June 2000 WES awarded AirPol Inc. of Parsippany, N.J. a turnkey contract for supply, installation and startup of a dedicated Gas Suspension Absorber (FLS miljo Inc GSA) upstream of each existing ESP. Under the contract AirPol also supplied a common lime slurry storage and preparation system, carbon storage and delivery system, ash conveying system, MCC, and control system..
The new APC system was commissioned and put into service in September, 2001. Initial stack testing was conducted in October 2001 to evaluate system performance. Compliance stack testing was conducted for the Utah Division of Air Quality in November 2001. Results of testing demonstrate that particulate, metals, acid gas and dioxin/furan emissions from the retrofit facility are substantially lower than required under, now final, Subpart BBB.
Facility Description
The Davis County Energy Recovery Facility consists of two mass burn refractory lined furnaces. The units each produce approximately 52,000 pph of steam at 550 psi and 515F.
Each incinerator was originally equipped with an Environmental Element Corporation (EEC) three field Electrostatic Precipitator (ESP) for control of particulate emissions. Acid gases were controlled by dry sorbent injection at the economizer inlet. Performance of the dry sorbent injection system was marginal due to short retention times and poorly controlled temperatures. The dry sorbent injection also aggravated fouling of the economizer section and increased particulate loading to the ESP.
Retrofit Air Pollution Control System
WES selected the semi-dry scrubber system proposed by AirPol Inc. and AirPol was awarded a contract for a turnkey installation at the DCERF. The existing dry sorbent injection system was removed from operation and one GSA was added upstream of each existing ESP. The semi-dry system uses pebbled lime for acid gas removal and Powdered Activated Carbon (PAC injection as an adsorbent for mercury and dioxin/furan control. In addition, the existing ESP structure had to be reinforced and larger Induced Draft Fans installed to meet the increased pressure drop across the GSA. A common lime slurry storage and preparation system, carbon storage and delivery system, ash conveying system, MCC, and control system were also included in the contract.
The GSA system is a patented process developed by FLS miljo a/s (Denmark), which was the parent company of AirPol from 1989 to 1998. During those nine years, AirPol specifically engaged in commercializing the GSA technology in the US and successfully installed nine GSAs in the US, Taiwan, and India. Subsequent to the change of ownership in July 1998, AirPol entered into an agreement with FLS miljo Inc. to sell, engineer, and execute selected GSA projects in the United States, Canada and Mexico.
To suit the general arrangement of the facility, each GSA was located upstream of the existing precipitators as shown in Figure 1. To maintain access to the existing precipitator, a length of ducktwork was provided which directs the flue gas from the economizer outlet to the GSA reactor and back to the ESP inlet.
System Performance
The new APC system was commissioned and put into service during September 2001. The startup in September on both systems went smoothly without encountering any substantial problems. Engineers from AirPol and WES checked each piece of equipment and subsystem thoroughly during the construction and pre-startup sage.
Purchasing records from the first six months of operation indicate an overall pebble lime consumption rate of approximately 13 lbs per ton of waste combusted. Results of testing indicate that performance objectives can be met with no carbon injection, however, the facility is currently injecting carbon at a rate of approximately 0.3 lbs per ton of waste combusted.
Engineering stack testing was conducted during October 2001 after minor operations issues had been resolved. The engineering testing was conducted by both AirPol and WES to assess system performance prior to the performance testing required by the Utah Division of Air Quality. Six 120-minute samples were collected.
Results of the engineering testing indicated the new APC system not only meets the contract performance guarantees, but also comfortably meets the federal standards under Subpart BBBB.
Conclusions
The performance of the new APC system not only meets the contractual guarantees but also comfortably meets the requirements of 40 CFR, Part 60, Subpart BBBB Emission Guidelines for Existing Small Municipal Waste Combustors.
Operation of the GSA system is relatively simple and has demonstrated more then 98% availability since system startup.
AirPol Description
For over 30 years AirPol has maintained its position as a leader in developing air pollution control systems. AirPol offers a "Total Service" concept whereby each system is specially designed and tailor-made to each specific application.
AirPol provides in-depth process knowledge and engineering expertise, and offers a complete package to meet any need.
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