Plywood and Composite Wood Products (PCWP): virtual tour

Control Devices

The available control device performance data for the PCWP industry shows that two types of add-on air pollution control devices are more likely to be used to reduce HAP and other gas emissions:

1. Incineration based controls
   
2. Biofilters

The main source of gas emissions is the veneer dryer, which emits significant quantities of organic compounds. The quantity and type of organic compounds emitted varies depending on the wood species, the dryer type, and its method of operation. Emissions from dryer heated zones and cooling sections typically are ducted through separate stacks. In addition to emissions from the heated zones and cooling section stacks, veneer dryer fugitive emissions may be emitted from the dryer ends and doors. The two discernible fractions released from the dryer are condensibles and volatiles. As the condensable compounds cool after being emitted from the stack; they often combine with water vapor to form aerosols, which can cause a blue haze.

The hot pressing operation is also a source of organic emissions. The quantity and composition of emissions from this operation will vary with wood species and resin components.

A gas emission control technology commonly used in the wood products industry for controlling veneer dryer exhaust gases is regenerative thermal oxidation (RTO). Regenerative catalytic oxidizers (RCOs) are also used to control gases. In addition to add-on thermal or catalytic oxidizers, exhaust gases from veneer dryers may be routed to the combustion chamber of an onsite boiler or process heater. The gas emissions in the process exhaust may be incinerated in the combustion chamber provided that the system is designed to allow for sufficient mixing and residence time.

Plywood Production Tour Sites