Diagnosis of the Non-Condensible Gas Collection System Operation, 1998 Environmental Conference Proceedings

Heikki Öhman

Reino Lammi

Jukka Kivivasara

UPM-Kymmene Corporation

Mika Järvensivu

Tom Mäenpää

Helsinki University of Technology

At a modern kraft pulp mill non-condensible gases are normally treated by collecting released gases into sealed systems and burning in some sort of furnace. However, due to the complexity of non-condensible gas (NCG) collection and treatment systems (and low priority as compared with pulp production) the knowledge of the NCG collection system operation, particularly during process upsets and fault situations is usually inadequate. To obtain a more complete picture of NCG collection system operations and emission rates during fault situations, more information about typical process upsets and short-term venting is required. Manual acquisition and processing of this type of information can be highly laborious, and more efficient procedures, such as automatic data acquisition and a monitoring system for NCG collection system, are required.

This paper presents results from an air emission inventory, in which the operation of both concentrated and dilute NCG collection systems were studied. During the emission inventory concentrations of the reduced sulphur compounds in large number of streams were analysed either by the manual or continuous analysers. In addition, a data logger together with movable temperature sensors was used to detect occasional emissions. Process measurements (such as levels, temperatures, pressures and flow rates) connected to the plant automation and information system were utilised to study the causes of occasional emissions. Furthermore, this paper presents means for earlier detection of emissions and possible action to eliminate (or at least minimise) occasional emissions. Finally, a ranking of the most important emission sources is presented.