Design and Feasibility Study of a Residual Heat Recovery Network for a Metal Surface Treatment Facility : Case Study for Polttoväri Oy

Abstract

This thesis explores the feasibility of recovering waste heat from the curing oven exhaust gases to minimise electricity use in the washing and pre-treatment process at Polttoväri Oy's production facility in Mustasaari, Finland. Currently, the company utilises electrical resistance heaters for heating the washing line tanks, simultaneously discharging significant amounts of waste heat from gas-powered curing ovens into the environment.

The theoretical background includes classifications of industrial waste heat, heat transfer processes (conduction, convection, and radiation), heat exchanger types, and thermal energy storage technologies. This research uses direct temperature readings obtained with the help of a TQC Sheen CurveX 3 Basic datalogger and K-type thermocouples, together with calculations performed in MS Excel.

It was discovered that the average heat dissipation rate of exhaust gases in DELTA LINE oven exhaust is equal to 3.64 kW and represents about 49.1% of the total daily heat need of AWL Tank 1, which equals 113.3kWh. A conceptual design of the waste heat recovery system consists of a copper coil heat exchanger, a 2000-litre buffer tank, and an electrical heating element as a backup option.