Omdimensionering av Lunds fjärrvärmenät

Sammanfattning: Lund is a rapidly growing city, and in a short time two new research facilities, ESS and MAX IV, will be completed. These facilities will deliver their excess heat to the district heating network of Lund which puts a high demand on the network. Kraftringen Energi AB, which owns and operates the network, are also in the process of replacing old pipes which motivates a through investigation of which pipe dimensions are optimal for the district heating network of Lund. This master thesis therefore aim to redimension the district heating network of Lund with consideration taken to today’s conditions. The pipes was in the model only allowed to take the same routes as today. The results were reached with the help of simulations in the computer software NetSim. NetSim is a network computing program which is used to calculate the flows of a district heating network, but can also be used to calculate suitable dimensions of the pipes in a network. In this report four different prospects were investigated, where each prospect describes different setup of heat production or a different expected heat consumption. For each prospect four different networks were created, with the help of NetSim. These four networks’ main difference was the overall size of the pipes. Each network was investigated to ensure that the technical requirements for district heating networks were met. The networks were then compared on the following criteria: building cost, operating costs, volume and how the flows were distributed in the networks. To compare the created networks with today’s district heating network of Lund, another model was created, the so called reference model. This model has the same dimensions and paths as the real district heating network. The pipes in the model however had lower heat losses from its pipes then the real network. This is to make it comparable to the created networks which utilizes only modern pipes with low heat losses. The results showed that the networks with overall smaller pipes had the lowest operation costs and the lowest building costs. The reference model has redundant pipe loops, which aim to increase the continuity of supply. The created networks lack redundant pipe loops, but have lower costs than the reference network. The networks in one of the prospects had the same conditions as the reference network. The most profitable of these networks had an operating cost which was around 20 % lower than the reference network’s. The same network had a building cost which was around 15 % lower then the reference networks. How the network should be designed depends on if one want redundant pipe loops or not. A general conclusion however is that the pipes in the current network of Lund should not be replaced by pipes with larger dimensions.