In English

Design of partial CO2 capture from waste fired CHP plants

Simon Öberg
Göteborg : Chalmers tekniska högskola, 2017. 71 s.
[Examensarbete på avancerad nivå]

In the Paris Agreement in 2015, it was stated that the temperature increase should be kept well below 2 °C above pre-industrial levels. As a response to the Paris Agreement, the Swedish government in February 2017 presented a climate reform to make Sweden CO2 neutral by 2045, and even CO2 negative beyond 2045. This requires extensive actions. One of the most required technical solutions is carbon capture and storage (CCS). One way of implementing CCS in a cost-efficient manner is in form of partial CO2 capture, where only a fraction of the emissions are captured. An important aspect of the Swedish energy system is the extensive use of waste incineration in combined heat and power (CHP) plants. This work evaluates the possibilities of making the Swedish waste fired CHP plants CO2 neutral by applying partial capture in order to capture the fossil share of the CO2 emissions. This work investigates the implementation of carbon capture through a post-combustion absorption process with monoethanolamine (MEA) as absorbent. Two design alternatives are evaluated for partial CO2 capture, based on either a high absorption rate for a fraction of the flue gas flow, or a low absorption rate for 100 % of the flue gas flow. The two designs are evaluated for a generic CHP plant, based on the average size of a Swedish waste fired CHP plant. Also, a specific case of Lillesjöverket is analyzed. Since seasonal variations in the heat load occur, both a constant annual operation and a seasonally optimized operation are considered for the design of the partial capture unit. The results show that the generic plant, which have fossil CO2 emissions of 64 200 ton per year, have a specific cost of 94-98 EUR/ton CO2 for a constant annual operation of the capture unit, but that the specific cost may be decreased to 86 EUR/ton CO2 if a seasonal operation is applied. Due to the small size of the capture unit, the capital cost is dominating and stands for more than 80 % of the specific cost. The capture unit should, thus, be designed to minimize the capture cost. The effect of implementing carbon capture on the other product streams of the CHP plant is significant, especially for Lillesjöverket that besides heat and electricity also produces pellets. In case waste incineration should be made CO2-neutral, the other products have to be prioritized based on price and season in order to maximize the revenue, and it can be concluded that the addition of a capture unit requires a system perspective analysis already in the planning and design phase.

Nyckelord: partial capture, post-combustion, waste incineration, seasonal operation

Publikationen registrerades 2017-08-02. Den ändrades senast 2017-08-02

CPL ID: 250871

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