CO2 Compression Research Articles

Measurement of relative static permittivity and solvatochromic parameters of binary and ternary CO2-expanded green solvents

CO2-expanded liquids (CXLs) is a class of solvent systems giving relatively low viscosity in comparison to neat organic solvents. The challenge is to achieve a high overall polarity of the CXL, despite the presence of compressed liquid CO2. In this study, the relative static permittivity (εr) was measured for binary and ternary one-phase mixtures of CO2 + green solvent using an in-line microfluidic device. In addition, Kamlet-Taft solvatochromic parameters were experimentally determined, allowing the characterization of the polarizability, acidity, and basicity. Novel data is shown for binary and ternary systems of CO2 expanded ethanol and ethyl lactate, with or without glycerol or water added, at moderate conditions of pressure and temperature (8 MPa and 35 °C). One-phase CXLs systems of a wide relative permittivity range (7.7–75.3) at lowered viscosity were enabled, by mixing different green solvents with CO2.

A Simple Mathematical Model and Computer Simulation of Non-isothermal Gas Absorption in Packed Tower

Oxygen-enriched combustion technology can effectively achieve residual capture, but the existence of acid gases such as NOx and SOx is not conducive to the transportation and storage of CO2. The compression of CO2 discharged from the packed tower is a necessary process before transportation. Therefore, the study of combined desulfurization and denitrification of flue gas under high pressure is of great significance to the application of carbon capture and storage technology. Based on the mass transfer coefficients obtained from experiments, a coupled model of mass transfer and kinetics of the bubbling reactor is established for the combination of reaction mechanism and kinetics of non-isothermal gases, and this unsteady state problem is solved by the Runge-Kutta mathematical method. The simulation study of the product changes in the process of NO and SO2 absorption alone and combined absorption under different pressures. The results show that: the interaction of NOx and SOx in the liquid phase promotes the absorption of SO2, NO2 and the mass production of and in the liquid phase, and it is also generates a large amount of greenhouse gas N2O; the increase in pressure is beneficial to , , The production of HADS and HAMS also led to an increase in the production of N2O.

Integration of biomass gasification with a supercritical CO2 and Kalina cycles in a combined heating and power system: A thermodynamic and exergoeconomic analysis

A novel cogeneration system based on a combination of a gas turbine cycle, a supercritical CO2 cycle, and a Kalina cycle is devised for heating and power generation. Energy, exergy, and exergoeconomic analysis are performed to assess the system’s performance and feasibility. According to the findings, the energy and exergy efficiencies of the system are obtained by 78.15% and 40.97%, respectively. In addition, heating capacity enhanced with the increment of air preheater’s terminal temperature difference (ΔTAP), air compressor’s pressure ratio (r1p), and pressure ratio of S–CO2 compressor (r2p). The system’s sum unit cost of the product (SUCP) decreased with the increment of ΔTAP and with the decrement of ammonia concentration. Besides, the minimum value of SUCP is obtained at the air compressor pressure ratio of r1p=13.24 and r2p=2.63. The maximum value of exergy efficiency is evaluated at ΔTAP=262K, r1p=14.5, and r2p=4.21. Moreover, the maximum net output power is obtained where the design parameters are set as ΔTAP=262K, r1p=14.5, and r2p=3.5. Furthermore, the economic analysis revealed that the payback period and net present value are evaluated to be 6.9 years and 5.374×10+6 $, respectively, for the electricity price of 0.07 $/kWh and fuel cost of 2 $/GJ.

Advanced Ultra-Supercritical Coal-Fired Power Plant with Post-Combustion Carbon Capture: Analysis of Electricity Penalty and CO2 Emission Reduction

This article presents the performance analysis of a 700 MW future planned advanced ultra-supercritical (A-USC) coal-fired power plant fitted with post-combustion carbon capture and storage (CCS) technology. The reference A-USC unit without CCS achieves a net efficiency of 47.6% with CO2 emissions of 700 kgCO2/MWh. Relatively to subcritical units, the net efficiency of the A-USC is 8%-pts higher while CO2 emissions are 16.5% lower. For a CO2 removal rate of 90%, the net efficiency of the CCS integrated A-USC unit is 36.8%. The resulting net efficiency loss is 10.8%-pts and the electricity output penalty is 362.3 kWhel/tCO2 for present state CCS technology. The study continues with the assessment of interface quantities between the capture unit and the steam cycle affecting the performance of the A-USC. Improved CO2 absorbents could alleviate the net efficiency loss by 2–3%-pts, and enhanced CO2 compression strategies and advanced heat integration could further reduce the efficiency loss by 0.5–1.2%-pts and 0.4–0.6%-pts, respectively. The total efficiency gain from CCS technology upgrades is estimated at 3.6%-pts, thus bringing down the net efficiency loss to 7.2%-pts and the electricity output penalty to 241.7 kWhel/tCO2.

Synthesis of ordered hierarchically mesoporous/microporous carbon materials via compressed CO2 for fructose-to-HMF transformation

Well-ordered hierarchically mesoporous/microporous carbon materials have been successfully fabricated by using dual soft-templating approach through compressed CO2. Pluronic F127 and different type of surfactants, including nonionic, cationic, and anionic surfactants, were used as dual templates to investigate the influence on the morphology and nanostructure of the as-prepared carbon samples. TEM, SEM, N2 sorption, wide-angle and small-angle XRD analysis were employed to reveal the well-ordered hierarchically micro-mesoporous structure with 2D hexagonal symmetry by using compressed CO2. The prepared HPC samples with different pressures as the catalyst carriers have been functioned by chlorosulfonic acid for the fructose conversion into HMF. Chlorosulfonic acid concentration, catalyst dosage and reaction temperature have been optimized for fructose-to-HMF transformation with the obtained catalyst. The performances of as-made HPC–SO3H samples in HMF yield and reaction rate of fructose-to-HMF transformation have been investigated. The stability of the samples was also conducted in the dehydration of fructose to HMF for five cycles. The possible catalytic mechanism by using hierarchically porous carbon materials as catalyst support for fructose-to-HMF transformation was proposed.

Thermoeconomic evaluation of double-reheat coal-fired power units with carbon capture and storage and waste heat recovery using organic Rankine cycle

Coal-fired power generation units using carbon capture and storage (CCS) can reduce CO2 emissions significantly whereas CCS consumes large amounts of renewable energy, leading to an efficiency penalty. To decrease the steam extraction and promote energy utilization efficiency, this study employs organic Rankine cycle (ORC) to recover the waste heat of reboiler condensate and utilizes the waste heat in CO2 compressed processes to provide energy for carbon capture system. Three technical scenarios are proposed: (1) Coal-fired carbon capture power generation system: the medium-pressure cylinder exhaust is throttled by an auxiliary turbine and exchanges heat with H6 heater to provide energy for a reboiler; (2) Coal-fired carbon capture power generation system using ORC to recover the residual heat of reboiler condensate; (3) Solar-aided coal-fired power generation system using ORC and CCS: waste heat in CO2 compression processes is supplied for a reboiler and ORC recovers the residual heat of reboiler condensate. The energy balance and overall performance of different scenarios are investigated with EBSILON, and the parameter sensitivity of scenario III is conducted. Results reveal that all scenarios improve the thermal performance of the system, and the thermo-economics of scenario III is the best at the heat ratio of 0.4.

Failure Analysis of Reciprocating CO2 Compressor

Failure Analysis of Reciprocating CO2 Compressor

Process safety challenges of CO2 sequestration

Sequestration of carbon dioxide (CO2) is an increasingly popular method of reducing the environmental impact of natural gas and blue hydrogen development projects. While the hazards associated with natural gas processing are well understood, high pressure CO2 presents unique challenges which must be overcome by designers to make sequestration a safe and practical option. Many of these hazards are ultimately due to the CO2 phase envelope. Compression of CO2 for injection into a reservoir can involve the creation of a dense phase fluid, which shares some of the properties of both liquid and gas. Upset conditions can also create either liquid or solid CO2. These can create unforeseen consequences such as potential blockage and overpressure of vent piping, condensation and freezing of free water and inaccurate level transmitter readings. Further, the partial pressures of CO2 involved mean that corrosion rates for any carbon steel exposed in the presence of free water may be as high as 1mm per week. These safety challenges and potential solutions to them will be explored in this study.

A high-throughput computational screening of potential adsorbents for a thermal compression CO2 Brayton cycle

The efficient utilization of thermal energy through MOF-based thermal compression CO2 Brayton cycle.

Cryogenic Carbon Capture™ Technoeconomic Analysis

The Cryogenic Carbon Capture™ (CCC) process significantly decreases cost and energy demands for CO2 separation and pressurization to 150 bar compared to alternatives. The process is a post-combustion technology that cools CO2-laden flue gas to desublimation temperatures (−100 to −135 °C), separates solid CO2—that forms from the flue gas—from the light gases, uses the cold products to cool incoming gases in a recuperative heat exchanger, compresses the solid/liquid CO2 to final pressures (100–200 bar), and delivers a compressed CO2 stream separated from an atmospheric pressure light-gas stream. The overall energy and economic costs are about 30-50% lower than most competing processes that involve air separation units (ASUs), solvents, or similar technologies. In addition, the CCC process enjoys several ancillary benefits, including (a) it is a minimally invasive Bolton technology, (b) it provides highly efficient removal of most pollutants (Hg, SOx, NO2, HCl, etc.), and (c) possible energy storage capacity. This report outlines the process details and economic and energy comparisons relative to other well-documented alternatives. This paper presents the results of a detailed techno-economic comparison of CCC with amine-based systems. The comparison uses identical financial and economic assumptions similar process assumptions as the detailed analyses published by US DOE in the greenfield analysis. Specifically, the comparison assumes power plants that produce the same net output, one equipped with and a second without carbon capture. Separately, the paper compares similar analyses for retrofitting existing systems using typical plant characteristics in the US (initial capital costs have been paid, high plant utilization), though there are no DOE estimates available for direct comparison. Financial and technical assumptions for all comparisons are maintained as close to the DOE reference studies as possible. The results demonstrate about 30-50% lower costs and energy demands for capture from greenfield coal plants. Natural gas plants produce substantially lower CO2 concentrations which makes the cost of capturing a ton of CO2 at the same capture rate as the coal plant higher for all processes while the cost of CO2 capture per unit of power generation is lower. However, CCC maintains about the same absolute energy and cost advantages for NG as for coal compared to amine systems. Finally, the costs of retrofitting a station are compared to those of building a new station with and without capture. The retrofit costs are comparable to (slightly lower than) new plant costs without capture. In all cases operating and capital cost comparisons show that the CCC process can be retrofitted to a variety of plants to cost effectively reduce CO2 emissions. Further process integration into the upstream processes and unique process features like water recovery, and integrated energy storage bring the effective cost of carbon capture using the CCC process down further and increase its advantages over alternatives. This technoeconomic analysis shows that the CCC process has the potential to the be lowest cost carbon capture technology under development today.

A Feasibility Study of Full Scale, Post Combustion, Amine Based, CO <sub>2</sub> Capture Retrofit Application in the Cement Manufacturing Sector at the Lehigh Hanson Materials Limited Facility

This paper will present the progress of a feasibility study, jointly conducted by Lehigh Hanson Materials Limited (Lehigh) and the International CCS Knowledge Centre, aimed at retrofitting a cement production facility at Lehigh (Edmonton, Alberta, Canada) with a full scale, post combustion, amine-based Carbon Dioxide (CO2) capture system. This study is a major breakthrough for carbon capture and storage (CCS) as it represents a first in North America for CCS application in the cement industry. The main deliverable of the feasibility study is a Class 4 estimate to assist Lehigh in determining the economic viability of a potential CCS retrofit project. This feasibility study commenced in November 2019 and will be complete in the fall of 2021 and is projected to cost $3.0M CAD. Funding for this study has been contributed to by Lehigh and Emissions Reduction Alberta (ERA) with contributions by the International CCS Knowledge Centre. The study will examine both the carbon capture technology and the “balance of plant”. Successful completion of this feasibility study could lead to a decision to carry out a Front End Engineering and Design (FEED) study and ultimately to a Final Investment Decision (FID) to implement a commercial scale project. A commercial project is projected to reduce emissions by approximately 600,000 tonnes of CO2 per year. The commercial scale project is projected to reduce emissions in Alberta in excess of 13.1 Mtonnes over a 25-year lifespan. The International CCS Knowledge Centre who is providing project management and advisory services, has engaged an experienced CO2 capture technology vendor, Mitsubishi Heavy Industries (MHI) Group, for the design of the CO2 capture system. MHI is responsible for the scope of work that includes the flue gas pretreatment system, the CO2 capture facility, and the CO2 compression process. The International CCS Knowledge Centre is also engaging and directing engineering consultants or other solution providers as appropriate. This direction and guidance will utilize base learnings from both the fully integrated Boundary Dam 3 CCS Facility and the comprehensive second-generation CCS study, known as the Shand CCS Feasibility Study, engineering consultants are being engaged to provide preliminary process and equipment design and cost estimates within their assigned scopes of work or work packages. The captured CO2 would be permanently sequestered and could be also used for Enhanced Oil Recovery (EOR). The Lehigh facility is located near potential storage locations, including being about 50 km away from the Alberta Carbon Trunk Line (ACTL) and nearby EOR opportunities. Lehigh, part of HeidelbergCement, will contribute to the company’s goal of achieving CO2-neutral concrete by 2050 at the latest and make it the most sustainable building material.

Numerical investigation of 660 MW pulverized coal-fired supercritical power plant retrofitted to oxy-coal combustion

A detailed investigation of the oxy-fuel combustion-based CCS consisting of air separation unit (ASU), supercritical boiler parameters and CO2 compression and purification unit (CPU) has been performed. A 660 MW supercritical power plant retrofitted to oxy-coal combustion has been simulated and analysed to investigate the operational characteristics of the oxy-coal combustion process by employing the process simulation tool Aspen plus. Moreover, the effect of important design parameters such as oxygen concentration of the oxidant, recycle ratio and purity of oxygen produced by ASU on the composition of flue gas, auxiliary power consumptions, CO2 recovery rate, CO2 product purity, and specific energy consumptions of O2 and CO2 has also been studied. The comparison of simulation results of the oxy-coal combustion and conventional air-fired combustion atmosphere has been presented. The excellent performance of oxy-coal combustion power plant has been observed in term of its ability to capture carbon dioxide with 95 % purity and 96 % recovery rate. The net efficiency of oxy-coal combustion power plant reduces by 10.4 % compared to the convention air-fired power plant.

Thermo-economic analysis on an improved coal-fired power system integrated with S–CO2 brayton cycle

In this work, the efficient energy utilization in the thermodynamic system of a traditional 660 MW coal-fired power plant, was achieved by incorporating S–CO2 Brayton cycle system. A thermodynamic mathematical model was established according to the basic laws of thermodynamics and was verified by using design conditions. Moreover, to minimize the irreversible losses, an additional S–CO2 Brayton cycle system was proposed under the THA condition, which increased the power generation efficiency by 0.28%, and decreased the coal consumption by 1.79 g/kwh. With the increase of the S–CO2 flow rate, a greater power generation efficiency was achieved. The outlet pressure of the S–CO2 compressor did not affect the plant load but affected the distribution of the power generation load between the steam cycle and the S–CO2 cycle. In addition, this study includes a technical-economic analysis of the proposed system. Overall, this study provides a complete picture of how to improve the efficiency of a thermal power plant.

Mathematical Modeling of Solar Energy based Thermal Energy Storage for House Heating in Winter

A novel solar thermal energy storage (TES) system for house heating purposes is modeled in the present study. The solar parabolic collector acts as a heat source to charge the TES using compressed CO2. The thermal energy in terms of sensible heat is stored in mild steel (MS) block wrapped in the thermal insulation material and buried in the ground at a certain depth. The stored energy will be used for house heating in the winter season. A mathematical model is developed to calculate the quantity of stored energy, consumption, and loss from TES along with the optimal storage volume of the block to fulfill the energy demand for house heating. Computational analysis of the 3D model is executed by adopting stipulated boundary conditions. Quantitative and qualitative studies of numerical results have been investigated for two cases: Initial charging and year-round performance. Numerical results revealed that the initial charging of the block takes in 55.2 days with maximum block temperature and stored energy as 324.2 °C and 2604 MJ, respectively. The average exergy efficiency and exergetic effectiveness of TES are observed as 49.9 % and 0.50, respectively. The partial charging of the block continued to compensate the heat losses after initial charging. The year-round performance of TES exhibits the reduction of stored energy by 71.6% at the end of January due to increased heating demand. Meanwhile, during a cyclic year, the average exergy efficiency and exergetic effectiveness of TES are noticed as 56.12 % and 0.76 respectively. The proposed TES has enough potential for year-round house heating since 28.4 % of net stored energy exists with the least block temperature of 106 °C. The rational economic study endorsed the proposed system 42.5% less expensive than the traditional heating methods for 50 years of utilization in addition to mitigating the average CO2 production of 5.655 Tons/year.

The Potential Impact of the U.S. Carbon Capture and Storage Tax Credit Expansion on the Economic Feasibility of Industrial Carbon Capture and Storage

In early 2018, the U.S. Congress expanded the 45Q tax credit program for the capture, storage, and utilization of CO2. The 45Q tax credit expansion creates a financial incentive of $50 for each tonne of CO2 placed in long-term storage, a significant increase from the $20 per tonne that was originally authorized in the Energy Policy Act of 2008. Here, we estimate the net present value of industrial carbon capture and storage with the $50 per tonne credit and find that in some industrial systems, the costs of capturing, transporting, and storing one tonne of CO2 is less than $50. For systems in which the $50 tax credit is not cost effective, economies of scale associated with small emissions quantities are limiting, and a simple gaseous transportation solution which saves on CO2 compression costs improves economics in some cases. However, the $50 tax credit is unlikely to be sufficient to stimulate changes in the management of most industrial CO2 emissions.

Process design and analysis of a novel carbon-capture-ready process for flexible-load power generation: Modular pressurized air combustion

The rapid retirement of dispatchable, fossil-based electricity sources and the influx of intermittent energy sources, both driven by the impetus towards a low-carbon future, have led to concerns about the reliability of the grid. The future need for on-demand, rotating, inertial-based assets that can be low carbon and flexibly meet changing demand to balance against intermittency will be essential. Hence, future fossil-based power generation will need to be highly efficient and flexible, and have the ability to add carbon capture when required. This study describes the process design of a modular pressurized air combustion power plant, which involves burning coal in air under pressure in parallel, modular boilers. After treatment, the high-pressure flue gas is passed through a series of turbines and inter-heaters to recover most of the compression work. The high-pressure operation allows for thermal recovery of the latent heat of moisture of the flue gas by integration into the steam cycle, which results in a plant efficiency that is 1.7% higher than that of the conventional atmospheric air-fired power plant. Moreover, the modularity enhances the flexibility of the power plant, with an improved ability for load following. This work also discusses the path to convert the modular, pressurized-air combustion process to a staged, pressurized oxy-combustion process, which is one of the most promising carbon capture processes. This can be accomplished by adding a frontend air separation unit and a backend CO2 compression and purification unit.

Production of Environmentally Friendly Polyester by Hydrogenation of Poly(butylene terephthalate) over Rh–Pt Catalysts Supported on Carbon Black and Recovery by a Compressed CO2 Antisolvent Technique

The direct hydrogenation of poly(butylene terephthalate) (PBT) using 1,1,1,3,3,3-hexafluro-2-propanol (HFIP) as the solvent to environmentally friendly polyester poly(butylene-1,4-cyclohexanedicarb...

A review of carbon dioxide disposal technology in the converter steelmaking process

In last decade, the utilization of CO2 resources in steelmaking has achieved certain metallurgical effects and the technology is maturing. In this review, we summarized the basic reaction theory of CO2, the CO2 conversion, and the change of energy-consumption when CO2 was introduced in converter steelmaking process. In the CO2-O2 mixed injection (COMI) process, the CO2 conversion ratio can be obtained as high as 80% or more with a control of the CO2 ratio in mixture gas and the flow rate of CO2, and the energy is saving and even the energy consumption can be reduced by 145.65 MJ/t under certain operations. In addition, a complete route of CO2 disposal technology is proposed combining the comparatively mature technologies of CO2 capture, CO2 compression, and liquid CO2 storage to improve the technology of CO2 utilization. The results are expected to form a large-scale, highly efficient, and valuable method to dispose of CO2.

A phase change calcium looping thermochemical energy storage system based on CaCO3/CaO-CaCl2

Calcium looping thermal energy storage (CaL-TES) is promising because of its high operating temperature, excellent energy storage density, and low material cost. However, a significant problem with the CaL-TES system is the rapid degradation of CaO. To overcome this degradation problem and also improve the energy storage performance, a novel phase change calcium looping thermal energy storage (PCCaL-TES) process has been developed based on the solid solution system of CaCO3/CaO-CaCl2. In the charging process of the PCCaL-TES system, surplus energy is stored via sensible heat, latent heat, and chemical energy with the calcination and melting of the solid solution CaCO3/CaO-CaCl2. In the discharging process, the carbonation and solidification of CaCO3/CaO-CaCl2 takes place and thus the stored energy is retrieved. Compared to the conventional CaL-TES system, the innovative PCCaL-TES system can help maintain a high activity of CaO over long-term operation due to the enhanced heat and mass transfer in the liquid-state carbonation. In this study, the energy storage performance of PCCaL-TES was assessed using the simulation package Aspen Plus v10. According to the modeling results, the PCCaL-TES system can achieve a round-trip efficiency of up to 49% and an energy storage density of nearly 1.5 GJ/m3, presenting improvements of about 4% and 20%, respectively, compared with the conventional CaL-TES system. Meanwhile, a parametric analysis was carried out to examine the effect of key operating parameters on the system performance of PCCaL-TES. The calculations show that the round-trip efficiency of the PCCaL-TES system can be improved by raising the mole fraction of CaCl2, increasing the carbonator temperature, or employing an optimum carbonator pressure. It was also found that a low mole fraction of CaCl2, a high activity of CaO, or a low temperature of CO2 storage was beneficial to achieving a high energy storage density. Finally, the impact of other operating factors on the round-trip efficiency of PCCaL-TES was summarized in a sensitivity analysis. It revealed the round-trip efficiency of the PCCaL-TES system was dominantly determined by the performance of the CO2 turbine (W-TURB) and compressor (W-COMP), the gas–liquid heat exchanger (HX3) and the exhaust CO2 cooler (CL3).

Optimum loss models for performance prediction of supercritical CO2 centrifugal compressor

Due to the lack of test data of a supercritical CO2 compressor operating under supercritical CO2 conditions, the work of loss model validation for supercritical CO2 compressor could not be conducted successfully before. Therefore, as the first step, this study gathers the existing accessible experiment data as much as possible while conducting additional supercritical CO2 compressor performance experiments to validate the loss models for the supercritical CO2 compressor. To evaluate the reliability of test results, the measurement uncertainty is estimated from the experiment data. Then, three different combinations of loss models based on the mean streamline method are compared with six available experimental cases to find the most suitable combination of loss models for the supercritical CO2 compressor design and analysis. The combination of loss models proposed by Lee was found to predict pressure ratio and isentropic efficiency of supercritical CO2 compressors operating both on-design and off-design conditions successfully. It is expected that the set of loss models presented herein can be utilized as a conceptual design tool in the preliminary design stage of supercritical CO2 compressors.