Carbon Capture & Sequestration: Integration af et MEA baseret CCS system på Nordjyllands Værket Blok 3

Carbon Capture & Sequestration: Integrating a MEA based CCS System at Nordjyllands Værket Unit 3

Fich, David Egede ; Herskind, Mark Burgdorf

4. term

Energy Engineering, Master

2009

132

Dette projekt undersøger, om det er muligt at integrere en CCS-enhed (CO2-fangst og -lagring) i det kulfyrede anlæg Nordjyllandsværket, Unit 3. Arbejdet er udført i samarbejde med Vattenfall, som investerer i teknologier, der kan reducere deres CO2-udledning. Nordjyllandsværket er valgt som teststed, fordi anlægget er meget effektivt, hvilket giver lave CO2-udledninger per produceret megawatt og derfor en relativt lavere omkostning ved CO2-fangst. Projektet samler viden om den nyeste udvikling inden for CCS gennem litteraturstudier og deltagelse i den 8. Annual Conference of Carbon Capture and Sequestration i Pittsburgh, USA. På den baggrund beskrives de mest lovende teknologier, hvordan de virker, og hvordan de ændrer et kraftværks design. Konklusionen er, at Vattenfalls fokus på MEA-baseret CO2-fangst (monoethanolamin) er rimeligt, da det i dag er den eneste løsning moden nok til fuldskala, men at andre opløsningsmidler og teknologier har stort potentiale. Der er udviklet forenklede computer-modeller af både dampkredsløbet og CCS-enheden i Engineering Equation Solver (EES). Trods anlæggets kompleksitet med bl.a. 10 fødevandsvarmevekslere, 9 turbiner, fjernvarme og dobbelt genopvarmning, kan dampkredsløbsmodellen gengive driften præcist ved både fuld last og dellast. Modellerne kræver gode startværdier for at kunne regne igennem. CCS-modellen bygger på oplysninger fra Vattenfall for fuldlast og er derfor kun gyldig ved fuldlast. I integrationsanalysen undersøges, hvor i dampkredsløbet den varme, som CCS-enheden behøver ved en bestemt temperatur, bedst kan tappes. Tre tappepunkter testes, og det energitab (energi-penalty), der opstår, vurderes. Analysen peger på det mest egnede tappepunkt og viser samtidig, hvor modellen er sårbar over for dårlige startværdier. Den første integration giver et mindre fald i elproduktionen og et betydeligt fald i fjernvarmeproduktionen. Samlet set bliver omkostningsstraffen for høj til at være økonomisk attraktiv uden yderligere forbedringer. Som forbedring foreslås det at udnytte CCS-enhedens lavtempererede spildvarme på ca. 309 MW ved at hæve dens temperatur med varmepumper. En simpel varmepumpemodel i EES viser, at der kan genvindes ca. 195,33 MW varme ved at bruge ca. 34,35 MW elektricitet. Det mindsker tabet af fjernvarme, men koster noget ekstra el. Konklusionen er, at modellerne rimeligt beskriver Unit 3’s ydeevne og viser, at integration af CCS og varmepumper er teknisk gennemførlig. Som forventet er omkostningsstraffen betydelig, men en gennemtænkt integration kan reducere den.

This project examines whether it is feasible to integrate a carbon capture and storage (CCS) unit into Nordjyllandsværket, Unit 3, a coal-fired power unit. The work was carried out with Vattenfall, which is investing in technologies to reduce its carbon footprint. Nordjyllandsværket was chosen as the test site because it is highly efficient, leading to low CO2 per megawatt and a relatively lower cost of capture. The project reviews the state of the art in CCS through literature and participation in the 8th Annual Conference of Carbon Capture and Sequestration in Pittsburgh, USA. It summarizes the most promising technologies, how they work, and how they affect power-plant design. The conclusion is that Vattenfall’s focus on MEA-based capture (monoethanolamine) is reasonable, as it is currently the only option mature enough for full-scale use, while other solvents and technologies also show strong potential. Simplified computer models of the plant’s steam cycle and the CCS unit were built in Engineering Equation Solver (EES). Despite the plant’s complexity—10 feedwater heat exchangers, 9 turbines, district heating, and double steam reheating—the steam-cycle model reproduces behavior accurately at full and partial load. The models require good starting values to solve reliably. The CCS model is based on information from Vattenfall for full-load conditions and is therefore valid only at full load. The integration study analyzes where to extract steam to provide the heat the CCS unit needs at a specific temperature. Three extraction points are tested, and the resulting energy penalty is evaluated. The analysis identifies the most suitable stream and highlights where the model is sensitive to poor starting values. Initial integration leads to a small loss in electricity production and a substantial loss in district heating output, making costs too high without further optimization. To improve performance, the project proposes using the CCS unit’s low-temperature waste heat—about 309 MW—by raising its temperature with heat pumps. A simple heat-pump model in EES suggests that about 195.33 MW of heat can be recovered using about 34.35 MW of electricity. This reduces the loss of district heating, at the expense of some extra electrical consumption. In conclusion, the models reasonably represent Unit 3’s performance and show that integrating CCS with heat pumps is technically feasible. As expected, CCS imposes a significant cost penalty, but careful integration can reduce it.

[This summary has been rewritten with the help of AI based on the project's original abstract]

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