Withdrawn Standard. Withdrawn Date: Feb 06, 2006. Recommendations on hopper heating system performance and equipment requirements necessary to provide an economical and effective hopper heating system are presented. System characteristics are described, and heat transfer analysis is covered. Heating module design considerations are presented. Control, monitoring, and alarm systems are discussed. Insulation, installation, operation, and maintenance are addressed.

Precipitators and baghouses are two systems designed to remove fly ash from boiler flue gas. Air pollution control regulations require that these precipitators and baghouses operate efficiently and reliably. Malfunctions or equipment failures could lead to boiler de-rating or complete shutdown, which increase the operation and maintenance expenses for the operating company. Problems related to fly ash collection in the hoppers, such as fly ash agglomeration and fly ash solidification, can lead to precipitator and baghouse shutdowns. The proper design and installation of hopper heating systems can significantly reduce the maintenance problems associated with fly ash plugging in hoppers.

This recommended practice is intended to define the system performance and equipment requirements to provide an economical and effective hopper heating system.