Flue gas carbonation of cement-based building products

Sensitivity of amine-based CO2 capture cost: The influences of CO2 concentration in flue gas and utility cost fluctuations

Modification of a 240 kWth grate incineration system for oxyfuel combustion of wood chips

The performance of ammonia‐based CO2 absorption under static magnetic field conditions was discussed. The removal efficiency of CO2, CO2 load, and absorption capacities were studied using a bubble reactor system. The CO2 removal efficiencies, CO2 load, and absorption capacity under static magnetic field conditions were calculated at four kinds of different operating conditions, which included CO2 concentration in flue gas, gas flow rate, concentrations of aqueous ammonia, and reaction temperature. The results indicated that the initial removal efficiency of CO2 can reach 98.5 % by 10 wt% ammonia solution under static magnetic field conditions, and it is 7 % higher than that under the no magnetic field conditions. The effect of magnetic field on CO2 load and absorption capacity is more obvious when the inlet CO2 concentration in the simulated flue gas is 10 vol%, the CO2 load increases 11.7 % from 1.45 mol/L to 1.62 mol/L, and the absorption capacity rises from 0.668 kgCO2/kgNH3 to 0.738 kgCO2/kgNH3. Compared with the absorption of CO2 under static magnetic field conditions and no magnetic field conditions, the absorption process of CO2 is enhanced by the magnetic field, and the removal efficiency of CO2, CO2 load and absorption capacity show superior performance.

Concrete demonstrates the capacity to absorb carbon dioxide. The reaction between concrete and carbon dioxide accelerates concrete curing at early age and converts CO2 into calcium carbonate for carbon storage. As-captured flue gas without recovery can be directly used in this application. Because of low CO2 concentration in flue gas, a pseudo-dynamic carbonation process was developed with multiple injection and releasing cycles. The effect of process parameters on carbon uptake and strength gain was examined. It was found that, with a flue gas of 25% CO2 concentration and 2-hour carbonation, cement paste could uptake CO2 of 8-11% based on cement content in immediate carbonation and concrete could absorb CO2 at 7-9% after 18-hour initial curing. The maximum possible carbon uptake from flue gas carbonation was also determined. It was about 15-17% based on cement mass. While immediate carbonation could significantly enhance the early strength, carbonation after initial curing did not improve significantly the late strength.

Integrating CO2 capture with biomass-fired combined heat and power (bio-CHP) plants is a promising method to achieve negative emissions. However, the use of versatile biomass, including waste, and the dynamic operation of bio-CHP plants leads to large fluctuations in the flowrate and CO2 concentration of the flue gas (FG), which further affect the operation of post-combustion CO2 capture. To optimize the dynamic operation of CO2 capture, a reliable model to predict the FG flowrate and CO2 concentration in real time is essential. In this paper, a data-driven model based on the Transformer architecture is developed. The model validation shows that the root mean squared error (RMSE), mean absolute percentage error (MAPE), and Pearson correlation coefficient (PPMCC) of Transformer are 0.3553, 0.0189, and 0.8099 respectively for the prediction of FG flowrate; and 13.137, 0.0318, and 0.8336 respectively for the prediction of CO2 concentration. The potential impact of various meteorological parameters on model accuracy is also assessed by analyzing the Shapley value. It is found that temperature and direct horizontal irradiance (DHI) are the most important factors, which should be selected as input features. In addition, using the near-infrared (NIR) spectral data as input features is also found to be an effective way to improve the prediction accuracy. It can reduce RMSE and MAPE for CO2 concentration from 0.2982 to 0.2887 and 0.0158 to 0.0157 respectively, and RMSE and MAPE for FG flowrate from 4.9854 to 4.7537 and 0.0141 to 0.0121 respectively. The Transformer model is also compared to other models, including long short-term memory network (LSTM) and artificial neural network (ANN), which results show that the Transformer model is superior in predicting complex dynamic patterns and nonlinear relationships.

ConspectusCarbon dioxide emissions from consumption of fossil fuels have caused serious climate issues. Rapid deployment of new energies makes renewable energy driven CO2 electroreduction to chemical feedstocks and carbon-neutral fuels a feasible and cost-effective pathway for achieving net-zero emission. With the urgency of the net-zero goal, we initiated our research on CO2 electrolysis with emphasis on industrial relevance.The CO2 molecules are thermodynamically stable due to high activation energy of the two C═O bonds, and efficient electrocatalysts are required to overcome the sluggish dynamics and competitive hydrogen evolution reaction. The CO2 electrocatalysts that we have explored include molecular catalysts and nanostructured catalysts. Molecular catalysts are centered on earth abundant elements such as Fe and Co for catalyzing CO2 reduction, and using Fe catalysts, we proposed an amidation strategy for reduction of CO2 to methanol, bypassing the inactive formate pathway. For nanostructured catalysts, we developed a carbon enrichment strategy using nitrogen-rich nanomaterials for selective CO2 reduction.Direct CO2 electroreduction from the flue gas stream represents the "holy grail" in the field, because typical CO2 concentration in flue gas is only 6-15%, posing a significant challenge for CO2 electrolysis. On the other hand, direct electroreduction of CO2 in the flue gas eliminates the carbon capture process and simplifies the overall carbon capture and utilization (CCU) scheme. However, direct flue gas reduction is frustrated by the reactive oxygen (5-8%), low CO2 concentration (6-15%), and potentially toxic impurities. Surface CO2 enrichment catalysts with high O2 tolerance could be viable for achieving direct CO2 electroreduction for decarbonization of flue gas.In addition to the electrocatalysts, the incorporation of catalysts into the electrolyzer and development of a suitable process was also investigated to meet industrial demands. A membrane electrode assembly (MEA) is a zero-gap configuration with cathode and anode catalysts coated on either side of an ion exchange membrane. We adopted the MEA configuration due to the structural simplicity, low ohmic resistance, and high efficiency. The electrode factors (for example, membrane type, catalyst layer porosity, and MEA fabrication method) and the electrolyzer factors (for example, flow channels, gas diffusion layer) are critical to highly efficient operation. We separately developed an anion-exchange membrane-based system for CO production and cation-exchange membrane-based system for formate production. The optimized electrolyzer configuration can generate uniform current and voltage distribution in a large-area electrolyzer and operate using an industrial CO2 stream. The optimized process was developed with the targets of long-term continuous operation and no electrolyte consumption.

On the membrane contactor test unit, chose monoethanolamine (MEA) as absorption solution to absorb CO2 of simulated flue gases, studied effects of operating parameters on CO2 capture. Operating parameters included initial CO2 contents in flue gas, flue gas flow and absorption solution flow. Experimental results showed that: the greater the absorption of fluid flow, the higher the CO2 removal rate;While the greater the flue gas flow or the higher the initial CO2 concentration in flue gas, the lower the CO2 removal rate. In order to study the influence of the regeneration solution on CO2 absorption efficiency, regeneration experiments were done. Since the loss of solvent in regeneration solution, CO2 removal efficiency by regeneration solution was lower than that by original absorption solution.

Carbon dioxide produced after combustion contains impurities that can be substantially corrosive. One study examined the use of flue gases to improve oil recovery from light oil reservoirs. Certain exhaust gas compositions can provide improved oil recovery in core flood experiments when compared with nitrogen displacement. Flue gas has been used in a few cases to re-pressurize a depleted reservoir. Reservoir re-pressurization raises production rates from the field and facilitates increasing the total ultimate recovery from the field. There are some air injection projects in the world that inject air in the reservoir. Typically such projects experience severe corrosion problems. In this paper we examine the ability of certain inhibitors to prevent corrosion of mild steel caused by impure CO2 (e.g., flue gases). In the first part of this report the compositions used to simulate exhaust wet flue gas are discussed. In the second part our experimental results using different corrosion inhibitors are presented. It is shown from this work that a new corrosion inhibitor is able to inhibit corrosion in environments that contain carbon dioxide and oxygen. This may have important implications in our ability to economically sequester carbon dioxide and use exhaust flue gas to re-pressurize a depleted reservoir.

Natural gas is expected to make up a significant proportion of the future global energy mix. Therefore, reducing greenhouse gas emissions from gas-fired processes is very essential for most countries, before emission reduction targets can be met. This article aims to carry out thermodynamic analysis of combined cycle gas turbine power plant with post-combustion CO2 capture through modelling and simulation. The combined cycle gas turbine power plant and the CO2 capture plant were simulated in Aspen Plus®. The combined cycle gas turbine power plant model was validated with simulation data from GateCycle® and the CO2 capture plant model was validated with experimental data from the pilot plant at the University of Texas at Austin. The CO2 capture plant was scaled up from pilot plant to commercial scale to process flue gas from a 250 MWe combined cycle gas turbine power plant. The integrated model for combined cycle gas turbine and CO2 capture plant was further used for performance study. Exhaust gas recirculation has been proposed to increase CO2 concentration in flue gas and reduce the flue gas flow rate. Its effect on combined cycle gas turbine power plant performance and capture plant sizing has been investigated. The analysis indicated that exhaust gas recirculation can reduce penalty on thermal efficiency without any major modification to the original power plant.

Grafting amine-functionalized ligand layer on catalyst for electrochemical CO2 capture and utilization

Experiment investigation of coal MILD-Oxy combustion integrated with flue gas recirculation at a 0.3 MWth furnace

Simulation analysis of CO2 in-situ enrichment technology of fluidized catalytic cracking regenerator

Carbon capturing and storage (CCS) is new technology to remove CO2 from the processes that involve elimination of CO2 as its effect on the environment and incessant increase in temperature of the Earth, makes it interesting as well as most dangerous issue that should be dealt timely to reduce the greenhouse gas emissions. In the present research, the data obtained from the experimental study of CO2 capture pilot plant at the Laboratory of Engineering Thermodynamic in TU Kaiserslautern, Germany, is used for the rate based model validation for different cases using monoethenolamine (MEA) as a solvent. Process simulation sensitivity analysis performed includes a wide range of CO2 concentrations for flue gas of different sources i.e. natural gas fired power plant, exhaust gas recycle and coal based power plant. Results obtained from sensitivity analysis point out the effects of lean loading, stripper pressure, MEA concentration and CO2 concentration in flue gas on energy requirement of reboiler and degree of regeneration using MEA as a solvent for a pilot-scale study. It was found that the specific reboiler duty is least for coal-fired power plant in comparison to the natural gas �fired and exhaust gas recycled power plant, keeping the flow rate of the flue gas constant.

The balance of contradictory factors in the selection of biodiesel and jet biofuels on algae fixation of flue gas

Thermodynamic analysis and techno-economic evaluation of an integrated natural gas combined cycle (NGCC) power plant with post-combustion CO2 capture