CO2 Pipeline Transport Research Articles

Towards Defining Reasonable Minimum Composition Thresholds – Impacts of Variable CO2 Stream Compositions on Transport, Injection and Storage

The collaborative project “Impacts of impurities in CO2 streams captured from different emitters in a regional cluster on transport, injection and storage (CLUSTER)” aimed to set up recommendations on how to define “reasonable minimum composition thresholds” that CO2 streams should meet when accessing CO2 transport pipeline networks. Within CLUSTER, we investigated potential impacts of CO2 streams with different and temporally variable compositions and mass flow rates along the whole CCS chain. Investigations included, amongst others, impacts on: • corrosion of pipeline steel, • pipeline network design and related transport costs, • alteration of well bore cements, • pressure development and rock integrity, • geochemical reactions, and • petrophysical and geomechanical rock properties. All investigations are based on a generic CCS chain scenario. In this scenario, CO2 streams are captured from a spatial cluster of eleven emitters and collected in a regional pipeline network. Emitters comprise seven fossil fuel-fired power plants equipped with different capture technologies, two cement plants, one refinery and one integrated iron and steel plant. In total, 19.78 Mio t CO2 (including impurities) are captured in the emitter cluster annually. The combined CO2 stream is transported in a trunk line with a length of 400 km (100 km of these offshore) and is injected into five generic storage structures. The storage reservoirs are saline aquifers of the Buntsandstein. The investigations revealed beneficial and deteriorating impacts of different impurities and combinations thereof. Overall, no fundamental technical obstacles for transporting, injecting and storing CO2 streams of the modelled variable compositions and mass flow rates were observed. Based on the results, the CLUSTER project team recommends not to define “minimum composition thresholds” for CO2 streams as strict threshold values for each individual impurity in the stream. Instead, CO2 stream compositions and variabilities for specific CCS projects should be constrained with regard to a set of parameters including i) the overall CO2 content, ii) maximum contents of relevant impurities or elements, iii) acceptable variability of CO2 stream composition, and iv) impurity combinations to be avoided.

Research Progress on Corrosion Behavior of Gaseous CO2 Transportation Pipelines Containing Impurities

Research Progress on Corrosion Behavior of Gaseous CO2 Transportation Pipelines Containing Impurities

Depressurization of CO2 in a pipe: High-resolution pressure and temperature data and comparison with model predictions

The design of safe and cost-efficient CO2-transportation systems is an integral part of CO2 capture and storage (CCS) deployment. To achieve this, accurate transient flow models capturing the occurrence of gas, liquid and solid CO2 are needed. These in turn rely on experimental validation. In this work, we present a new experimental facility designed to capture pressure and temperature during the depressurization of CO2 and CO2-rich mixtures in a tube at high spatial and temporal resolution. Experiments with pure CO2 starting from both gaseous and dense (liquid) states are presented, and a reference experiment with N2 is included. The experimental results for both pressure and temperature are analysed by comparison with predictions by a homogeneous equilibrium model. Emphasis is put on the decompression-wave speed, of particular relevance for running-ductile fracture in CO2-transportation pipelines. We observe good agreement with predicted decompression-wave speeds in the single-phase region, and fair agreement for two-phase flows when the calculations are based on the assumption of equilibrium. However, the observed ‘pressure plateau’, a key factor in the prediction of running-ductile fracture, can be significantly lower than that calculated assuming equilibrium.

Techno-Economic Assessment of a Combined Heat and Power Plant Integrated with Carbon Dioxide Removal Technology: A Case Study for Central Poland

The objective of this study is to assess the techno-economic potential of the proposed novel energy system, which allows for negative emissions of carbon dioxide (CO2). The analyzed system comprises four main subsystems: a biomass-fired combined heat and power plant integrated with a CO2 capture and compression unit, a CO2 transport pipeline, a CO2-enhanced geothermal system, and a supercritical CO2 Brayton power cycle. For the purpose of the comprehensive techno-economic assessment, the results for the reference biomass-fired combined heat and power plant without CO2 capture are also presented. Based on the proposed framework for energy and economic assessment, the energy efficiencies, the specific primary energy consumption of CO2 avoidance, the cost of CO2 avoidance, and negative CO2 emissions are evaluated based on the results of process simulations. In addition, an overview of the relevant elements of the whole system is provided, taking into account technological progress and technology readiness levels. The specific primary energy consumption per unit of CO2 avoided in the analyzed system is equal to 2.17 MJLHV/kg CO2 for biomass only (and 6.22 MJLHV/kg CO2 when geothermal energy is included) and 3.41 MJLHV/kg CO2 excluding the CO2 utilization in the enhanced geothermal system. Regarding the economic performance of the analyzed system, the levelized cost of electricity and heat are almost two times higher than those of the reference system (239.0 to 127.5 EUR/MWh and 9.4 to 5.0 EUR/GJ), which leads to negative values of the Net Present Value in all analyzed scenarios. The CO2 avoided cost and CO2 negative cost in the business as usual economic scenario are equal to 63.0 and 48.2 EUR/t CO2, respectively, and drop to 27.3 and 20 EUR/t CO2 in the technological development scenario. The analysis proves the economic feasibility of the proposed CO2 utilization and storage option in the enhanced geothermal system integrated with the sCO2 cycle when the cost of CO2 transport and storage is above 10 EUR/t CO2 (at a transport distance of 50 km). The technology readiness level of the proposed technology was assessed as TRL4 (technological development), mainly due to the early stage of the CO2-enhanced geothermal systems development.

Influence of SO2 on the corrosion and stress corrosion cracking susceptibility of supercritical CO2 transportation pipelines

The impacts of SO2 on corrosion and stress corrosion cracking (SCC) of supercritical CO2 (s-CO2) pipeline steels are unclear because of limited field operation experience and somewhat controversial reported results. Comprehensive literature review and corresponding tests in the s-CO2 streams from advanced oxy-fuel plants were performed to fill significant knowledge gaps. The presence of SO2 leads to severe general corrosion but does not initiate SCC of the steels in H2O-saturated s-CO2. SO2 induced corrosion is likely dominated by electrochemical reactions. It is necessary to control H2O% < 2000 ppm and SO2% <100 ppm to avoid potential catastrophic disaster.

Nitric and Sulfuric Acid Solubility in Dense Phase CO2

Research has shown that strong acids (i.e., sulfuric and nitric acids) may be produced as a result of reactions between impurities during CO2 transport within carbon capture, utilization and storage (CCUS) systems even when today’s impurity specifications and recommendations are followed. Strong acids are corrosive to carbon steel, which is a very common construction material for CO2 transport pipelines. To establish acceptable impurity limits and to ensure the integrity of pipelines, experimental data are needed as input for modelling possible scenarios and as a foundation for constructing modelling tools. To assess the possibility of formation of concentrated acid-bearing phases in CO2 environments, acid solubility in dense phase CO2 needs to be determined. The nitric and sulfuric acid solubilities in dense phase CO2 were determined by first saturating the CO2 phase with the acids, and by subsequently scrubbing the acids using water-filled autoclaves. The water was then analysed using ion chromatography...

Effect of Pipe Diameter and Inlet Parameters on Liquid CO2 Flow in Transportation by Pipeline with Large Height Difference

Fire prevention and extinguishing and CO2 sequestration in coal mine gob require continuous transportation of liquid CO2 in pipelines with large height difference (from ground to underground). However, the temperature and pressure variation of liquid CO2 in pipelines with large height difference is still unclear, which hinders the design of a liquid CO2 pipeline transportation system. The influence of pipe diameter and inlet parameters (temperature and pressure) on the variation of temperature and pressure of liquid CO2 along the 1000 m vertical pipeline was studied in this paper. The study found that for each pipeline diameter considered there existed a range of flowrates where safe flow conditions could be ensured, at which no phase transition occurs throughout the length of the pipeline. When the transporting flow is larger than the maximum limit flow, phase transition occurs dramatically, which will lead to a sudden drop in temperature and pressure. When the transporting flow rate is lower than the minimum limit flow rate, phase transition of CO2 occurs slowly along the pipeline. According to the requirement of underground fire prevention and extinguishing for transporting flow rate and the economic cost of the pipeline system, the optimum diameter is 32 mm, and the corresponding safe transporting flow range is 507–13,826 kg/h. In addition, when the inlet pressure is constant, if the inlet temperature is too high, phase transition of CO2 occurs dramatically at the entrance. For a 1000 m vertical pipe with diameter of 32 mm, when the inlet pressure is 14 bar, 16 bar, 18 bar, 20 bar, 22 bar, 24 bar, the corresponding maximum allowable inlet temperatures are −30 °C, −26 °C, −23 °C, −19 °C, −16 °C and −13 °C, respectively. This research has significant guidance for safety transportation scheme of liquid CO2 from coal mine surface to underground.

Effect of SO2, O2, NO2, and H2O Concentrations on Chemical Reactions and Corrosion of Carbon Steel in Dense Phase CO2

Carbon capture, utilization, and storage is expected to be an important method for reducing CO2emissions to prevent global warming. Several species (impurities) could follow the CO2through the capture plant as carry over. It is expected that nitrogen dioxide (NO2), sulfur dioxide (SO2), oxygen (O2), and water (H2O) can be present as impurities (concentrations at the ppmv level) in the captured CO2. The exact composition will depend on the flue gas type, the CO2capturing process, and multiple other parameters. Some of these impurities are reactive and may cause corrosion in carbon steel pipelines and could therefore be a threat for safe CO2transport. The present study used a novel experimental setup to realistically simulate a CO2transport pipeline system with a controlled and variable concentration of impurities at a total pressure of 10 MPa and a temperature of 25°C. The water concentration was increased and decreased with constant concentration of SO2and O2, to observe and identify possible reactions or threshold levels which could cause corrosion. A similar experiment was conducted with NO2. First, experiments were performed without steel coupons, to observe uncatalyzed reactions, and then with coupons to measure corrosion rates. The first sign of corrosion appeared at 350 ppmv of water with NO2present. At 670 ppmv water with 75 ppmv NO2the overall corrosion rate was about 0.57 mm/y and the main product was iron oxide. The corrosion process for SO2, O2, and water was much slower, and the first sign of corrosion appeared around 1,900 ppmv of water, with about 75 ppmv of SO2and 230 ppmv of O2. The corrosion rate increased some when the water concentration was increased to 2,400 ppmv, but the overall corrosion rate was only 3.6 μm/y and the main product on the surface was iron sulfate.

A Review of Pipeline Transportation Technology of Carbon Dioxide

CO2from industrial production is captured and stored to be buried underground or used for driving oil or gas(CCS). The CCS technology can be used not only to mitigate environmental pollution and reduce the anthropogenic greenhouse effect, but to improve economic efficiency. CO2 transportation is imperative, and pipeline transportation is the most economical and convenient way for CO2 transportation because of its features such as large-throughput, long-distance and reliable-operation. According to the different phases, CO2 pipeline transportation can be divided into gas phase, liquid phase, dense phase and supercritical transportation. In this paper, the characteristics and application ranges of three kinds of pipeline transportation process were analyzed, finally in a design influence factors of pipeline transportation were analyzed, and faced currently of problems were shown.

Contact angle and corrosion of a Water – CO2 system on X70 and S41500 at 278 K and pressures up to 20 MPa

Interfacial properties related to wettability and corrosion in CO2 transport pipelines are experimentally determined by the sessile and the pendant drop methods. The contact angle of a water drop in a compressed CO2 atmosphere is analyzed on an X70 pipeline carbon steel and compared to that on a martensitic steel S41500 to elucidate the effect of corrosion process on active wetting behaviour. The measurements are performed with liquid CO2 at 278 K and pressures ranging from 5 to 20 MPa. The results show that the contact angle (CA) increases with pressure from 132° to 143° for S41500 and from 117° to 137° for X70 and decreases with drop age by 20° to 24° regardless of the pressure and of the fact that corrosion only occurs on X70, which is confirmed by scanning electron microscopy, element mapping and energy dispersive x-ray spectrometry (EDS) analysis. At higher pressure, the contact angles on both materials converge. Further, related properties like density and interfacial tension (IFT) were determined. CO2 - saturated water has a higher density than pure water: At 5 MPa saturated water reaches a density of 1017 kg⋅m-3 and at 20 MPa 1026 kg⋅m-3 compared to pure water with a density of 1002 kg⋅m-3 and 1009 kg⋅m-3, respectively. In this pressure range the IFT drops from 33 mN⋅m-1 at 5 MPa to 23 mN⋅m-1 at 20 MPa.

Insights into the Interfacial Process in Electroless Ni-P Coating on Supercritical CO2 Transport Pipeline as Relevant to Carbon Capture and Storage.

To reduce the amount of greenhouse gas emissions and remedy related environmental damage, the research on carbon capture and storage (CCS) is gaining momentum and so is the search for a more effective way to control corrosion of pipeline steel used to transport impure supercritical (SC) CO2. Herein, we prepared an electroless high-phosphorus Ni-P coating and, for the first time, systematically explored the underlying mechanism of the interfacial process in applying Ni-P coating to protect pipeline steel that transports impure SC CO2. It is found that, benefiting from the formation of a protective surface film, Ni-P coating significantly mitigates the corrosion effects from SC CO2 and impurities (e.g., O2 and NO2), especially the synergistic effect of impurities. Concurrently, it effectively avoids the localized corrosion resulting from nonuniform adsorption of the aqueous phase. Although O2 and NO2 can degrade the coating through boosting water precipitation, deteriorating the water chemistry, and reducing the surface film protectiveness, the corrosion inhibition efficiency of Ni-P coating is invariably higher than 80%, independent of the varying causticity of SC CO2 streams, demonstrating that the coating has a superior stability toward corrosion attack. The as-prepared Ni-P coating undoubtedly holds great potential as an alternative for corrosion control of CO2 transport pipeline in the CCS industry. This work provides a new, feasible method to ensure the safe and efficient operation of CCS.

Critical water content for corrosion of X65 mild steel in gaseous, liquid and supercritical CO2 stream

CO2 could be transported by pipelines in gaseous, liquid or supercritical phase depending on the operating temperature and pressure. Safety concerns might arise from CO2 transportation pipeline, especially crossing the densely populated areas. Water content is critical to understand corrosion mechanism of CO2 pipeline. Corrosion behavior of API 5L X65 mild steel exposed to CO2 environment with different relative humidity (RH), temperature and pressure was investigated by weight-loss and surface analysis techniques to determine critical water content in gaseous, liquid and supercritical CO2 stream. Surface morphology of coupons and composition of corrosion product layers were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Results showed that general corrosion rates remained steady with the increasing of RH before a separate water phase was observed, and it experienced a remarkable increase in free water for all test conditions. Localized corrosion or severe general corrosion was observed when the relative humidity was beyond 60% at 25 °C and 35 °C, 8 MPa and 80% at 35 °C, 4 MPa. The critical water content in CO2 stream was determined to be 60% RH for liquid and supercritical and 80% RH for gaseous CO2 transportation due to the safety concern of X65 pipeline on the basis of corrosion study.

An experimental study on the flow characteristics during the leakage of high pressure CO2 pipelines

High pressure pipeline transportation is dominant mode for economically transporting large amounts of CO2. However, potential leakage is one of the main risks associated with pressurized CO2 pipeline transportation. Thus, to investigate the leakage behavior of high pressure CO2 and to de-risk such transportations, a new laboratory scale experimental setup (total length of 14.85 m and the inner diameter of 15 mm) was constructed. Leakage experiments for pure CO2 and CO2 mixtures containing various N2 concentrations were carried out for different initial phase states (supercritical, liquid and gaseous respectively). The pressure and temperature characteristics and phase transitions of high pressure CO2 were then studied following pipeline leakage through small diameter nozzles. The results show that a minimum temperature occurs during the leakage process of various initial phase states; while the temperature characteristics of supercritical and gaseous CO2 leakage were rather different from that of liquid CO2 leakage. Impacts of impurity (N2), initial inner pressure and nozzle sizes on the leakage behavior were investigated, and two minimum temperature lines, based on N2 concentrations and initial inner pressures were obtained, respectively. These findings will ascertain that the pipeline is operated above the ductile-brittle transition temperature.

Suggestions for plant parameters to monitor potential CO2 leakage from carbon capture and storage (CCS) sites

AbstractPotential CO2 leakage from carbon capture and storage (CCS) facilities should be monitored and managed carefully. Biomonitoring technologies for CO2 leakage using plants could be very effective, especially in areas near transport pipelines, because of the extensive areas that they can cover. A greenhouse study was conducted to investigate whether early changes in plant parameters could be an effective indicator to detect leaked CO2. Corn (Zea mays), which was reported to be a CO2‐tolerant species, was selected to identify specific indicators of CO2 leakage. The mean soil CO2 concentration for soil treated with CO2 was 20–40%, which is similar to the concentration that could occur near transport pipelines through slow‐insidious seepage. In the soil treated with CO2, the number of yellow leaves at the canopy level was significantly increased from the sixth day of CO2 injection compared to the control. The chlorophyll content in green leaves was significantly reduced on the eighth day from CO2 injection. The soil water content in the treated soil was increased from the sixth day of injection due to reduced root adsorption. The results of this study implied that early changes in parameters of CO2‐tolerant species such as canopy‐level discoloration and chlorophyll content could be used as CO2‐specific indicators for the detection of soil CO2 leakage. We suggested that canopy‐level monitoring is a promising, useful technique for soil CO2 leakage in extensive areas, such as near CO2 transport pipelines. In addition, rhizosphere‐level parameters, such as soil water content, could be good subsidiary indicators together with the large‐scale collection of baseline data and statistical analysis. © 2019 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

A nonlinear interval number programming algorithm for CO2 pipeline transportation design under uncertainties

AbstractCarbon capture, utilization and storage (CCUS) technology includes three sub‐systems of CO2 capture: transportation, utilization, and storage. Pipeline transportation is the middle link of CCUS, and its optimization is closely connected with the other two sub‐systems. However, technical and economic parameter uncertainties strongly affect the optimal pipeline cost, which creates a need for flexibility in pipeline design. To solve the flexible optimization design problem in CO2 pipeline transportation, this paper proposes an interval number optimization algorithm. Average levelized cost and system robustness are given as the optimization objectives. A two‐objective, two‐level, two‐step optimization problem is established and solved using a quantum genetic algorithm (QGA). The proposed interval number optimization algorithm makes the optimization process with good decision space, the decision makers can flexibly make decisions based on experimental analysis and subjective preference, and the designed pipeline transportation is flexible and can be combined with the optimization of the other sub‐systems. It can also attain the goal of coordination and unification of CCUS optimization. Numerical studies show that the proposed method can solve the flexible optimization problem effectively in the presence of uncertainties. © 2019 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

On the Corrosion Mechanism of CO₂ Transport Pipeline Steel Caused by Condensate: Synergistic Effects of NO₂ and SO₂.

To study the effects of condensed acid liquid, hereafter referred to as condensate, on the CO2 transport pipeline steels, gas mixtures containing a varying concentration of H2O, O2, NO2, and SO2, were proposed and resulted in the condensate containing H2SO4 and HNO3 with the pH ranging from 0.5 to 2.5. By exposing the pipeline steel to the synthetic condensate with different concentration of acidic components, the corrosion kinetic is significantly changed. Reaction kinetic was studied using electrochemical methods coupled with water analysis and compared with surface analysis (scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffractometry (XRD)) of corroded coupons. The results showed that, although the condensation of NO2 in the form of HNO3 causes faster general corrosion rate, it is the condensation of SO2 in the form of H2SO4 or the combination of SO2 and NO2 that may cause much more severe problems in the form of localized and pitting corrosions. The resulting corrosion forms were depended on the chemical nature of acids and their concentration at the same investigated pH. The effects of changing CO2 flow rate and renewing condensate on pitting corrosion were further studied.

Experimental and numerical analysis of non-premixed oxy-combustion of hydrogen-enriched propane in a swirl stabilized combustor

Oxyfuel combustion is a promising carbon capture and sequestration technology. The use of CO2 diluent in oxyfuel combustion can lead to flame instability. In this study, the effect of hydrogen enrichment on the blowout limits of propane oxyfuel flames under CO2 dilution was analyzed experimentally and numerically in a swirl-stabilized, non-premixed combustor. Results show that increasing the hydrogen concentration from 0 to 30% extends the blowout limits of the CO2 diluted oxyfuel flames by 2.5%. Hydrogen enrichment, however, was found to increase CO while lowering CO2 emission as a consequence of the low residence time and competition for oxygen between the fuel species. In this regard, the minimum amount of CO2 emission recorded (74.3%) corresponds to a maximum CO emission of (1.93%) at hydrogen concentration of 40%. Increasing the gases residence time in the combustor lowers the CO emission which is desirable since beyond certain limit, CO in exhaust gases can promote the formation of pentacarbonyls that can damage CO2 transportation pipelines aimed at CCS. Decreasing the equivalence ratio from 1.0 to 0.9 also leads to a significant reduction in CO emission from 8000 ppm to <1 ppm. The flames, however, display better stability at higher equivalence ratios.

Instability Analysis of Supercritical CO2 during Transportation and Injection in Carbon Capture and Storage Systems

Captured CO2 is in a subcritical state, whereas CO2 deep underground is in a supercritical state because of the high geothermal heat and pressure. The properties of CO2 can change rapidly at the critical point and in the near-critical region during the transportation and injection process. This study aims to identify the instabilities in the CO2 flow in these regions, along with the causes and effects, during the transportation and injection process, and propose relevant design specifications. Thus, the critical points and near-critical region of CO2 flow were numerically analyzed. The unstable region is presented in terms of temperature and pressure ranges, and the changes in the CO2 properties in this region were analyzed. In the unstable region, the sudden change in density was similar to the density wave oscillation of a two-phase flow. The CO2 stability map we obtained and the stability map of supercritical water show similar trends. Flow instability was also found to occur in standard CO2 transportation pipelines. We demonstrate that flow instability in CO2 transportation and injection systems can be avoided by maintaining the proposed conditions.

Integrated absorption–mineralisation for energy-efficient CO2 sequestration: Reaction mechanism and feasibility of using fly ash as a feedstock

The most critical challenge for the large-scale implementation of amine-based carbon dioxide (CO2) capture is the high energy consumption of absorbent thermal regeneration. To reduce the energy requirement, absorbent thermal regeneration can be replaced by a chemical method that integrates amine scrubbing, chemical regeneration and CO2mineralisation in one process. However, the mechanisms of the process and the application of industrial waste as feedstocks have not been fully investigated. In the present work, we studied the integrated CO2 absorption–mineralisation process using the benchmark solvent monoethanolamine (MEA) as an amine absorbent and fly ash as a chemical regeneration agent. We investigated the mechanism involved in the mineralisation in detail and studied the performance of MEA in regeneration bymineralisation of calcium oxide (CaO) at various CO2-loadings. The performance stability of MEA was verified in multicycle CO2 absorption–mineralisation experiments. We also investigated the technical feasibility of using fly ash as a feedstock for absorbent regeneration. Our results show that MEA can be regenerated after a carbonation reactionwith both calcium oxide and fly ash at 40 °C, and that the CO2 absorbed by MEA is precipitated as calcium carbonate. Compared with traditional thermal regeneration-based CO2 capture, the integrated CO2 absorption–mineralisation process displays a similar cyclic CO2-loading (0.21 mol/mol) but has great advantages in energy reduction and capital cost savings due to the smaller energy requirement of amine regeneration and the limitation of CO2 compression and pipeline transport. This technology has great potential for industrial application, particularly with CaO-containing wastes such as fly ash and carbide slag.

Optimization of CCUS Source-Sink Matching for Large Coal-Fired Units: A Case of North China

Climate change has become an important part of the human destiny community, China faces dual pressures both at home and abroad for carbon dioxide (CO2) emission reductions, and the clean coal utilization and low-carbon development in China will be the key development direction in the future. This study takes the city or country with a coal-fired unit above 300 MW in North China as a CO2 source and the basin in North China and its surrounding area as a CO2 sink, and estimates distances between sources and sinks by ArcGIS. Through modelling and optimizing the cost of carbon capture, utilization and storage (CCUS) source-sink matching for North China in the next 30 years, it results that the best solution for source-sink matching is obtained, the total CO2 capture volume from coal-fired power plants reaches approximate 22.8 billion tons, the total CCUS cost is about $1.78 trillion, the unit cost is about $78/ton CO2, and the CO2 transport pipeline network is about 52,876 km, which provides a data support and methodological reference for further research on China’s CCUS source-sink matching.