Mánudaginn 1. júní kl. 14:00 mun Theodór Júlíus Blöndal verja 30 ECTS verkefni sitt til meistaragráðu í vélaverkfræði „Design and location of heat exchangers for waste heat recovery from Alcoa Fjarðaál"

• Stofa: M208 og eru öll velkomin.
• Nemandi:  Theodór Júlíus Blöndal
• Leiðbeinandi:  María Sigríður Guðjónsdóttir, Guðrún Arnbjörg Sævarsdóttir, og Leo Blær Haraldsson
• Prófdómari: Michael Moorhead

Teams hlekkur hér

Útdráttur:

Large amounts of thermal energy are rejected as waste heat in industrial processes, creating opportunities for improved energy efficiency and local energy utilization. At Alcoa Fjarðaál in Reyðarfjörður, Iceland, significant heat is carried by exhaust gases from the aluminium smelting process. Previous studies have indicated that this resource may be sufficient to support district heating in Reyðarfjörður. However, less attention has been given to the practical challenges of integrating such a system into an operating aluminum smelter such as Alcoa Fjarðaál.

The objective of this thesis was to develop and justify a realistic preliminary design for a

waste heat recovery system capable of supplying the district heating demand of Reyðarfjörður with minimal disruption to smelter operation. The work focused on identifying a suitable installation location within the existing exhaust system, preliminary sizing of heat exchangers,   pressure drop limitations, bypass routing, and implementation considerations.

Shell and tube heat exchangers with exhaust gas on the tube side were evaluated in order to reduce fouling risk and limit gas side pressure losses. Candidate tube configurations were compared based on thermal and hydraulic performance as well as heat exchanger size.

The proposed design consists of four parallel shell and tube heat exchanger units, each rated at approximately 1.3 MW𝑡ℎ, providing a combined heat recovery capacity of about 5.2 MW𝑡ℎ.

A configuration using DN150 tubes and shell diameters of approximately 3.5 m was identified as a suitable balance between physical size and pressure loss. The total additional pressure loss of the waste heat recovery system was estimated to be 192 Pa, leaving a good margin for the allowable pressure margin of approximately 300 Pa of additional pressure loss at the intended location of waste heat recovery.

The results indicate that waste heat recovery from Alcoa Fjarðaál is technically achievable through integration into the existing exhaust infrastructure. The study provides a basis for future detailed design, economic assessment, and implementation planning.