Operational flexibility options in power plants with integrated post-combustion capture

Flexibility in power plants with amine based carbon dioxide (CO2) capture is widely recognised as a way of improving power plant revenues. Despite the prior art, its value as a way to improve power plant revenues is still unclear. Most studies are based on simplifying assumptions about the capabilities of power plants to operate at part load and to regenerate additional solvent after interim storage of solvent. This work addresses this gap by examining the operational flexibility of supercritical coal power plants with amine based CO2 capture, using a rigorous fully integrated model. The part-load performance with capture and with additional solvent regeneration, of two coal-fired supercritical power plant configurations designed for base load operation with capture, and with the ability to fully bypass capture, is reported. With advanced integration options configuration, including boiler sliding pressure control, uncontrolled steam extraction with a floating crossover pressure, constant stripper pressure operation and compressor inlet guide vanes, a significant reduction of the electricity output penalty at part load is observed. For instance at 50% fuel input and 90% capture, the electricity output penalty reduces from 458 kWh/tCO2 (with conventional integration options) to 345 kWh/tCO2 (with advanced integration options), compared to a reduction from 361 kWh/tCO2 to 342 kWh/tCO2 at 100% fuel input and 90% capture. However, advanced integration options allow for additional solvent regeneration to a lower magnitude than conventional integration options. The latter can maintain CO2 flow export within 10% of maximum flow across 30–78% of MCR (maximum continuous rating). For this configuration, one hour of interim solvent storage at 100% MCR is evaluated to be optimally regenerated in 4 h at 55% MCR, and 3 h at 30% MCR, providing rigorously validated useful guidelines for the increasing number of techno-economic studies on power plant flexibility, and CO2 flow profiles for further studies on integrated CO2 networks

Sequential supplementary firing in combined cycle power plant with carbon capture: part-load operation scenarios in the context of EOR

This paper extends previous work on sequential supplementary firing combined cycles (SSFCC) and evaluates their part-load operation in order to define operating strategies to maximise revenue from electricity and Enhanced Oil Recovery (EOR) over a range of fuel input. Sequential supplementary firing consists of burning additional fuel at different stages in the heat recovery steam generator (HRSG) to increase CO2 concentration reduces the volumetric flow of the flue gases. It uses almost all of the oxygen in the flue gas and keeps the maximum gas temperature at around 820 °C to avoid large additional capital costs in the HRSG. SSFCC This analysis is important in order to establish ways to maintain a minimum CO2 flow for EOR when the power plant with CO2 capture is at minimum stable generation. Two alternatives to reduce power at part-load are evaluated: a subcritical steam cycle with a combination of variable inlet guide vanes and reduction in supplementary firing; and a strategy where the gas turbine is maintained at full output and the power output is solely reduced by adjusting the amount of supplementary firing in the HRSG

Post-combustion carbon dioxide capture cost reduction to 2030 and beyond

Post-combustion CO2 capture (PCC) can be achieved using a variety of technologies. Importantly it is applicable to a wide range of processes and may also be retrofitted in certain cases. This paper covers the use of PCC for low carbon power generation from new natural gas combined cycle (NGCC) plants that are expected to be built in the UK in the 2020s and 2030s and that will run into the 2050s. Costs appear potentially comparable with other low carbon and controllable generation sources such as nuclear or renewables plus storage, especially with the lower gas prices that can be expected in a carbon-constrained world. Non-fuel cost reduction is still, however, desirable and, since CO2 capture is a new application, significant potential is likely to exist. For the NGCC+PCC examples shown in this paper, moving from ‘first of a kind’ (FOAK) to ‘nth of a kind’ (NOAK) gives significant improvements through both reduced financing costs and capital cost reductions. To achieve this the main emphasis needs to be on ‘commercial readiness’, rather than on system-level ‘technical readiness’, and on improvements through innovation activities, supported by underpinning research, that develop novel sub-processes; this will also maintain NOAK status for cost-effective financing. Feasible reductions in the energy penalty for PCC capture have much less impact, reflecting the inherently high levels of efficiency for modern NGCC+PCC plants

Thermal integration of waste to energy plants with post-combustion CO2 capture

Waste-to-Energy (WtE) is becoming an important application sector for carbon capture utilization and storage (CCS) due to its role in urban waste management and its inherent potential of achieving negative emissions. This study is built upon a series of modelling activities, with three representative WtE plant steam cycle configurations selected to integrate monoethanolamine (MEA) based Post-combustion CO2 Capture (PCC). With 60% biogenic carbon in the fuel, a set of key performance indicators of the investigated WtE plant configurations are presented. Results show that there is significant potential for heat recovery from the PCC process to provide heat for District Heating (DH). With advanced heat recovery, the energy utility factor (EUF) of WtE plant could be higher than that for WtE plant without PCC. Results also show that optimised process design can be used to enable ultra-high CO2 capture (99.72% in this study) to be achieved with only a marginal increase in specific reboiler duty when compared with 95% capture. This study also highlights the importance of differentiating carbon intensities for different product bases: electrical or thermal or waste, which are important when comparing WtE CCS with other carbon saving technologies. The findings of this study provide valuable information for the future implementation of carbon dioxide capture technology in the WtE sector

Priority projects for the implementation of CCS power generation with enhanced oil recovery in Mexico

In March 2014, Mexico launched its CCUS technology roadmap, outlining the actions to be taken up to 2024. One important action is the National Policy of Carbon Capture and Storage (CCS) ready and the identification of priority natural gas combined cycle (NGCC) with capture plants. This outcome could aid the creation of a technology roadmap for the design of new NGCC power plants and their operational requirements for EOR and for the reduction of CO 2 emissions. This article provides an overview of the opportunities for deploying CCS in new NGCC power plants in Mexico which were programed to begin operation throughout the period from 2016 to 2030. The attention is given to plants close to oil fields which are candidates for enhanced oil recovery (EOR), located in an inclusion zone suitable for storage. The Gulf of Mexico region, where potential EOR sites and the presence of industrial CO 2 sources are located, is within the inclusion zone for recommended sites for geological storage of CO 2 . After identifying new power plants in the inclusion zone, this article analyses which existing plants could be retrofitted and which new power plants could be designed to be ‘carbon capture ready’. In addition, the distance and the volumes of CO 2 are estimated

Process intensification for post combustion CO₂ capture with chemical absorption: a critical review

The concentration of CO₂ in the atmosphere is increasing rapidly. CO₂ emissions may have an impact on global climate change. Effective CO₂ emission abatement strategies such as carbon capture and storage (CCS) are required to combat this trend. Compared with pre-combustion carbon capture and oxy-fuel carbon capture approaches, post-combustion CO₂ capture (PCC) using solvent process is one of the most mature carbon capture technologies. There are two main barriers for the PCC process using solvent to be commercially deployed: (a) high capital cost; (b) high thermal efficiency penalty due to solvent regeneration. Applying process intensification (PI) technology into PCC with solvent process has the potential to significantly reduce capital costs compared with conventional technology using packed columns. This paper intends to evaluate different PI technologies for their suitability in PCC process. The study shows that rotating packed bed (RPB) absorber/stripper has attracted much interest due to its high mass transfer capability. Currently experimental studies on CO₂ capture using RPB are based on standalone absorber or stripper. Therefore a schematic process flow diagram of intensified PCC process is proposed so as to motivate other researches for possible optimal design, operation and control. To intensify heat transfer in reboiler, spinning disc technology is recommended. To replace cross heat exchanger in conventional PCC (with packed column) process, printed circuit heat exchanger will be preferred. Solvent selection for conventional PCC process has been studied extensively. However, it needs more studies for solvent selection in intensified PCC process. The authors also predicted research challenges in intensified PCC process and potential new breakthrough from different aspects

Process simulation and analysis of carbon capture with an aqueous mixture of ionic liquid and monoethanolamine solvent

This study investigated the prospect of using aqueous mixture of 1-butylpyridinium tetrafluoroborate ([Bpy][BF4]) ionic liquid (IL) and monoethanolamine (MEA) as solvent in post-combustion CO2 capture (PCC) process. This is done by analysis of the process through modelling and simulation. In literature, reported PCC models with a mixture of IL and MEA solvent were developed using equilibrium-based mass transfer approach. In contrast, the model in this study is developed using rate-based mass transfer approach in Aspen Plus®. From the results, the mixed aqueous solvent with 5–30 wt% IL and 30 wt% MEA showed 7%–9% and 12%–27% less specific regeneration energy and solvent circulation rate respectively compared to commonly used 30 wt% MEA solvent. It is concluded that the IL concentration (wt%) in the solvent blend have significant impact on specific regeneration energy and solvent circulation rate. This study is a starting point for further research on technical and economic analysis of PCC process with aqueous blend of IL and MEA as solvent