Analys och optimering av värmesystemet vid centrallasarettet i Karlskrona, för att möjliggöra en ekonomisk och hållbar drift vid låg last

Commissioned by the Blekinge County Council, I have been tasked to investigate the possibilities for optimizing the hospital in Karlskrona systems for hot water and steam production based on what is economically beneficial and environmentally sustainable in the summer period 15 May to 30 September. Today, the production of hot water and steam is provided by a wood chip boiler during winter, spring and autumn and with the combination of an electrical boiler and district heating during the summer due to the wood chip boiler not being able to be fired toward the low loads that occur during the warmer months. The combined production of both the electric boiler and district heating, has proven to be considerably more expensive than if the production could have been done with the wood chip boiler, due to the high electricity- and district heating prices. Blekinge County Council wishes to examine what measures could be taken for a more sustainable and economical production during the warmer months. The measures that have been investigated in this report is the application of an absorption chiller for increased heating surface, a small additional chip boiler and the cost of district heating at a possible cessation of steamproduction. The report shows that the proposed solutions are possible options for an economically beneficial and environmentally sustainable production during the warmer months. All solutions resulting reportedly in a cheaper and more sustainable production of hot water and steam, and with repayment periods that are lower than the depreciation and economic life. The solution that in short terms proves more profitable, in terms of cost per MWh and paybacktime, is the application of an absorption chiller. The report shows, however, that a greater cooling load than what has been investigated in the report is desired for optimized sustainability. A small additional chip boiler also results in a lower productioncost than today, albeit with a longer paybacktime due to a higher investment cost. Advantages of an additional chip boiler, which is mentioned in the report, is that this option also results in a more sustainable and cheaper supplement at the tip of the loads during the colder months. Continued production with district heating alone is a third option which is being investigated, and that could be seen as advantageous if the hospital would choose to settle the central steam system. This work shows that the proposed solutions would be approximately 140-279 kronor cheaper per MWh during the solutions economical lifetime and with the current prices an installment periods of 0-24 years