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Industry:  Paper Products
Project Type:  StackVision DAS Implementation
Scope:  2 Boilers & 1 Common Stack
Driver:  Boiler MACT revisions
Regulation(s):  40CFR63 Subpart DDDDD (Boiler MACT)
Parameter(s):  HCl, CO, Opacity
Location:  Wisconsin
Year:  2018

Project Description

The boilers provide power and steam to the mill. The first boiler primarily burns biomass, with coal as an alternate fuel. The other burns entirely coal. Boiler MACT rules require a site-wide limit on applicable pollutants for the affected boilers. The original RFP for this project called for HCl to be measured at the common stack, but the design evolved over the permitting process. Each boiler is controlled by a Multi-Cyclone, Electrostatic Precipitator (ESP), and Dry Sorbent Injection System (Hydrated Lime).

Problems or Requirements

Inconsistent Solid Fuels in the Biomass Boiler
Like many papermills, the owners of this facility take advantage of the ready-made source of hogged fuel (wood debris from forestry). They also burn sludge from a wastewater treatment plant. They only burn these solid fuels in one of the boilers (it burns coal as an alternate fuel). This makes the emissions from this boiler much more variable than the other.
Boiler MACT Revisions Forced Changes
The facility had to look for a DAS vendor that could handle the range of CEMS, COMS and CPMS required for continuous monitoring under the Boiler MACT. Compliance with the Boiler MACT revisions is simplest for newer boilers designed to burn natural gas or which were converted. Older solid fuel burners like this mill have more controls and recordkeeping.
Electronic Reporting Required
The Boiler MACT revisions, like most recent RTR revisions, included a requirement to report electronically through EPA's Compliance and Emissions Data Reporting Interface (CEDRI) tool. The CEDRI Reports tool in StackVision allows them to directly generate reports in the format required by CEDRI.

Solutions and Outcomes

Decision to Isolate Monitoring of HCl
After working through the permitting process, flue gas monitoring of HCl was placed after the ESP for each boiler and prior to entering the common stack. This configuration lets plant personnel react better to the variable emissions of the biomass boiler and take advantage of emissions averaging between the two units.
COMS on Common Stack
Located similarly in the ductwork is an opacity sensor for the biomass boiler, but not the coal boiler. A Continuous Opacity Monitoring System (COMS) for combined opacity is on the common stack.
CEMS Shelter Monitoring
Monitoring and alarming for climate control, smoke/gas detection and power for the CEMS shelter was included in the design. This is common because the data controllers make it simple for CEMS technicians to add and manage most kinds of signal input and alarms output, to accommodate changes over time.

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