Concentrated Aqueous Piperazine as CO2 Capture Solvent: Detailed Evaluation of the Integration with a Power Plant☆

AbstractAn integrated energetic evaluation has been performed of a reference coal-fired power plant, a power plant with an advanced MEA-based post-combustion CO2 capture plant, and a power plant with a capture plant using concentrated piperazine (PZ) and high-pressure flash regeneration. This comparison shows that using a MEA-based capture plant reduces the net electric efficiency from 44.6% to 35.5%, while the PZ-based capture plant reduces it to 37.4%, corresponding to an efficiency penalty of only 7.2%

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

Electrochemical method for producing valeric acid

The invention is directed to a method of electrochemically producing valeric acid. The method of the invention comprises - contacting a solution of levulinic acid with an anode and a cathode in an electrochemical cell; and - electrochemically reducing levulinic acid at the cathode to form valeric acid, wherein the cathode comprises one or more materials selected from the group consisting of cadmium, zinc, and indium

DECAB: process development of a phase change absorption process

This work describes the conceptual design of a novel separation process for CO2 removal from flue gas based on precipitating solvents. The process here described (DECAB) is an enhanced CO2 absorption based on the Le Chatelier's principle, which states that reaction equilibrium can be shifted by removing one of the constituents in the reaction. A conceptual design of this process has been developed based on literature data, thermodynamic principles and a limited number of experiments. As solvent example, the potassium salt of taurine was selected. The strategy followed is based on the compilation and determination of the key properties and parameters that govern the absorption and regeneration of the solvent. Then, the performance of the process is evaluated with the aid of short cut design methods. Results show that the key advantages of this process are environmental friendliness (no emissions to the air) and low energy consumption related to a lower vapor pressure of the solvent and higher net loading than conventional processes. The design developed allows for future economic evaluation and assessment of options that will further lead to benefits over conventional processes. © 2011 Published by Elsevier Ltd

High Level Analysis of CO2 Capture on LNG Fuelled Ships

Recently, there has been an increased level of interest from the maritime sector towards ship based carbon capture (SBCC) as a way to achieve at least 50% emission reduction by 2050. The SBCC technology works especially well when integrated on LNG fuelled ships, which drastically reduces the variable OPEX of the system. This study considers the integration of a CO2 capture, liquefaction and temporary on-board storage plant on a hypothetical LNG fuelled ship. It is found that by heat integration of the exhaust gas with the capture plant, and the LNG vaporization with CO2 liquefaction, a capture percentage of ca. 80% can be achieved, using the available utilities. Additionally, a techno-economic analysis has been conducted which has shown that for the hypothetical vessel discussed in this work, the cost of CO2 capture is 168 €/ton CO2. For the future perspective, considering higher average loads of the engine/ship, and standardization of the technology, the cost of CO2 capture could theoretically drop to 45 €/ton CO2

COSMO-RS-based extractant screening for phenol extraction as model system

The focus of this investigation is the development of a fast and reliable extractant screening approach. Phenol extraction is selected as the model process. A quantum chemical conductor-like screening model for real solvents (COSMO-RS) is combined with molecular design considerations. For this purpose, phenol distribution coefficients KD of known phenol extractants are determined experimentally and in silico. Molecular variations of different extractants are tested concerning their effect on KD to facilitate extractant improvement. It is shown that KD depends on the molecular structure of the extractant. Calculations with COSMO-RS provide a qualitative trend of simulated extraction efficiency and even a quantitatively correct description of KD. The simulations for alkylamine components are, however, not accurate, which is a well-known problem. During the screening process, phosphorus containing aliphatic substances, especially the trialkylphosphine oxide compound Cyanex 923, were determined as the most promising phenol extractants, which agrees with the state of the art

High Level Analysis of CO2 Capture in the Waste-To-Energy Sector

There is currently a large amount of interest from the Waste-to-Energy (WtE) sector in Europe towards implementation of post-combustion carbon capture technology. This study gives a high level analysis of the implementation of a CO2 capture plant (no post-treatment of the captured CO2 is considered) for three generic WtE plants that process 60, 200 and 500 kton of waste per year respectively. The heat and electricity demand of the plants are analysed and compared to the energy generation of the reference WtE plant. It is shown that regardless of the size of the plant, approximately 53% of the steam for district heating and 5% of the electricity generation of the reference WtE plant is needed to run the CO2 capture plant. Additionally, a techno-economic analysis has been conducted that shows that the expected costs for a CO2 capture plant are 30 to 55 €/ton CO2 captured, depending on the considered scale. Additionally, it is shown that for smaller WtE plants, CAPEX is the dominant factor, while for larger WtE plants, the variable OPEX is dominating