This study aims to provide a comprehensive comparison of different configurations of amine-based Post-combustion carbon capture (PCC) using Mono-Ethanol Amine and activated Methyl Di-Ethanol Amine ...(MEA and a-MDEA) solvents. A base case simulation model of a process with MEA is developed and validated at two capture rates, of 20 and 2000 tonnes per day, with the data reported in a study prepared by Nexant. The model was then used for a 1900 tonnes-per-day capture facility, and several combinations of substantial process modifications, including absorber intercooling (AIC), lean vapor recompression (LVR), and parallel exchanger arrangement (PEA) are investigated. Various scenarios for the two amine-based solvents are simulated in Aspen HYSYS®, and the results are compared with a base case conventional process for the same solvent. Results from the studied scenarios showed that a-MDEA with AIC-LVR modifications is a more attractive option due to an 8% reduction in stripper reboiler energy and its associated steam costs. The analysis of the studied cases showed that the effect of solvent on energy saving is more important than that of process modification, with the combined effect of both modification and solvent bringing higher benefits. It is also concluded that a complex process such as PCC with AIC-LVR-PEA modifications has the highest energy savings although it is less cost-effective. While OPEX (Operating Expenditure) values (mainly associated with utility steam and cooling water consumption) are still considerable, we ended up with CAPEX-intensive (Capital Expenditure) capture plants. For typical PCC equipped with combined AIC and LVR modifications (total capital investments of $136 million and $147 million were estimated for MEA and a-MDEA, respectively, translating to capture costs of US$58.80 and US$53.80 per tonne of CO2 captured. Potential savings of approximately 4–15% (for MEA) and 3–12% (for a-MDEA) were calculated depending on the scenario of combined process modifications among a shortlist of attractive options. These energy reductions portray promising reductions in the energy consumption imposed by an amine absorption-based PCC technology.
•Different configurations of amine-based carbon captures is compared thoroughly.•Savings of up to 15% are estimated due on several process modifications.•Modified a-MDEA is the most attractive option with 8% steam saving in stripping.•Impact of process modifications on energy savings is higher than solvent type.•Complex process modifications results in higher energy savings and higher cost.
Pulp-and-paper mills produce various types of contaminants and a significant amount of wastewater depending on the type of processes used in the plant. Since the generated wastewaters can be ...potentially polluting and very dangerous, they should be treated in wastewater treatment plants before being released to the environment. This paper reviews different wastewater treatment processes used in the pulp-and-paper industry and compares them with respect to their contaminant removal efficiencies and the extent of greenhouse gas (GHG) emission. It also evaluates the impact of operating parameters on the performance of different treatment processes. Two mathematical models were used to estimate GHG emission in common biological treatment processes used in the pulp-and-paper industry. Nutrient removal processes and sludge treatment are discussed and their associated GHG emissions are calculated. Although both aerobic and anaerobic biological processes are appropriate for wastewater treatment, their combination known as hybrid processes showed a better contaminant removal capacity at higher efficiencies under optimized operating conditions with reduced GHG emission and energy costs.
•Wastewater treatment techniques used in pulp-and-paper industry are reviewed.•Numerical models are developed to estimate GHG emissions for each technique.•Contaminant removal efficiencies and GHG emissions depend on operating parameters.•Hybrid process is found to be the most appropriate and stable treatment technique.
•Energy performance of SAGD plants was optimized with and without carbon capture.•Advanced amine and novel solid adsorbent were considered for carbon capture.•Process integration led to energy and ...water synergies between the two processes.•13% to 47% of the regeneration energy can be provided by heat recovery.•Cost analysis showed a capture cost of $35–56/t-CO2 for different configurations.
The Canadian in-situ bitumen extraction is one of the most energy-intensive processes and a large GHG producer. In an increasingly carbon-constrained environment, industry and technology developers aim towards decarbonization of their operations by considering several design strategies. Post-combustion carbon capture (PCC) and heat integration are available solutions that can significantly reduce GHG emissions produced by in-situ extraction plants such as steam-assisted gravity drainage (SAGD) facilities. An important challenge that currently limits the use of carbon capture in SAGD facilities, apart from the capital cost, is the large quantity of energy needed and the associated GHG emissions. In this work, the energy performance of two typical SAGD configurations was optimized with and without PCC technologies. Aspen HYSYS® was used to model each configuration for a standard capacity and CanmetENERGY’s INTEGRATION software was used to optimize heat recovery. First, it was shown that SAGD facilities’ energy consumption and GHG emissions could be reduced by up to 8% through optimized heat recovery leading to a significant increase in the boiler feedwater and combustion air temperatures. Then, two PCC technologies were integrated into the SAGD configurations. Several energy integration strategies were considered to provide part of the regeneration energy required in the PCC units by using the excess heat in the SAGD and PCC plants. The analysis revealed that, depending on the SAGD process configuration, the PCC technology considered and the level of heat integration within the SAGD plant, 13–47% of the regeneration energy could be provided by heat recovery. Additionally, the techno-economic analysis results showed a capture cost of US$34.6–55.3/t-CO2 for different studied scenarios.
•A new system for methanol production based on the novel electrified combined-reforming process has been introduced.•Electrified combined-reforming process can reduce hydrogen demand by 88.4 % ...compared to the conventional tri-reforming one.•A comprehensive comparison between the lifecycle emissions of the E-CRM and other methanol production pathways is conducted across Canada.•The proposed E-CRM-90 system is more environmentally friendly in terms of GHG emissions in the average of Canada than other processes.
In this work, we developed an effective approach for the conversion of CO2 by incorporating the electrified combined reforming reactor (E-CRM). The process simulation and life cycle assessment (LCA) of the proposed process are conducted considering a variety of recycling ratios of the unreacted syngas to the main reformer using Aspen Plus software. The simulation results show that the electrification of the proposed reforming process can significantly improve the overall efficiency of the process compared to a reference process. The key factors such as hydrogen demand (88.4 % reduction), net electricity consumption (17 % reduction), thermal efficiency (16.7 % increase), and methanol production (7.5 % increase) are improved. Furthermore, the LCA of the proposed process is conducted using openLCA software and results are compared with those of the CO2 hydrogenation and conventional methanol production processes for various geographical locations in Canada. The LCA results showed that the E-CRM with 90 recycling of unreacted gases (E-CRM-90) is an environmentally attractive option with the lowest greenhouse gas emissions when the carbon intensity of the electricity is equal to or lower than that of the average value in Canada.
This work focuses on the design and analysis of innovative environmentally friendly pathways to produce low-density polyethylene and high-density polyethylene, as the main feedstock of petrochemical ...industries, based on CO2 capture and utilization. For each polymer, the process development and simulation of the proposed pathways are performed using Aspen Plus. Each pathway includes the following units: CO2 capture from flue gas, hydrogen production via electrolysis of water, methanol production, olefin production, and polymerization of ethylene. Moreover, the greenhouse gas emissions of the proposed pathways are compared to those of the conventional method i.e., steam cracking. The midpoint and endpoint lifecycle assessment of each pathway are conducted using TRACI 2.1 and ReCiPe Endpoint (H, A) lifecycle impact assessment methods in the OpenLCA software, respectively, for various geographical locations, electricity sources and assessment scenarios for the incorporation of the by-products. The lifecycle assessment results show that the new pathway is an environmentally attractive option, particularly in regions where renewable (low-carbon) electricity is more prominent, such as Quebec and Ontario provinces in Canada. In such regions, negative CO2 emissions, as low as −6.1 kg CO2eq/kg polymer, can be achieved. However, in locations where coal or natural gas are the main sources of electricity generation, such as Alberta, lifecycle emissions increase to 20 times the emissions of the conventional method. Furthermore, the impact of incorporating alternative methanol production processes is evaluated. Results show that using the tri-reforming of methane as an effective syngas production technology from CO2 and natural gas can reduce the lifecycle greenhouse gas emissions by up to 94% and 62%, compared to the conventional high- and low-density polyethylene production pathways.
•Design and simulation of CO2-based pathway for polyethylene production.•Cradle-to-gate comparative lifecycle assessment is performed.•The new production pathway allows for a significant decrease in CO2e emissions.•The novel pathway is recommended in areas where low-carbon electricity is available.
•Design improvements are introduced in a biomass-derived syngas purification process.•Four scenarios are identified to reduce thermodynamic inefficiencies.•Improved designs are based on optimal heat ...recovery and ejector integration.•Techno-economic analysis of the proposed improvements showed reasonable economics.•The proposed scenarios can lead to substantial steam and cooling water savings.
This work introduces design improvements for an integrated biomass-derived syngas purification process based on a holistic integration approach. Optimal heat recovery measures and ejector integration are used as key components of the proposed designs in order to valorize untapped waste heat and reduce energy inefficiencies within this process. The steam saving in the solvent regeneration column of the acid gas removal unit that uses MDEA solvent is considered as a key performance indicator to assess the proposed designs since it represents the major part of the whole gas purification process’s operating costs. We used Aspen HYSYS® to assess technical feasibility and economic viability of the proposed designs. We found that combining optimal heat recovery and ejector integration led to the overall process seeing substantial utility savings. More precisely, we showed that this approach can reduce steam and cooling water consumption by up to 23 % and 16 %, respectively.
•Process design and simulation of four methanol production pathways are studied.•Several heat integration measures are considered to maximize thermal efficiency.•Cradle-to-gate and well-to-wheel GHG ...life cycle assessment is performed.•Simulation results shows 47.8 % thermal efficiency for CO2 hydrogenation pathway.•CO2 hydrogenation is recommended only where low-carbon electricity is available.
The process design and life cycle assessment (LCA) of various methanol production processes, including the conventional natural gas reforming process and alternative CO2 utilization-based pathways, are performed in this work. Three main technologies are considered for the CO2 conversion to methanol: direct CO2 hydrogenation, dry reforming and tri-reforming of methane. For each pathway, a process simulation that includes the CO2 capture from typical flue gas of a cement kiln, the methanol synthesis and purification steps, is performed using the Aspen engineering suite. In addition, for each process, several heat integration measures are considered to maximize thermal efficiency. According to the simulation results, the thermal efficiency of the direct CO2 hydrogenation process (47.8 % LHV) is higher than the dry reforming (40.6 % LHV) while it is lower than the conventional (68.4 % LHV) and tri-reforming (57.9 % LHV) processes. The LCA results showed that the direct CO2 hydrogenation pathway is an environmentally friendly option, only when the electricity GHG intensity is lower than 0.17 kg CO2 equivalent per kWh of electricity. As a result, in the context of Canada, the CO2 hydrogenation options can be recommended only for the provinces where low-carbon electricity is available, such as Quebec, British Columbia, Manitoba and Ontario.
Pinch Analysis was used to improve the energy performance of a typical steam-assisted gravity drainage (SAGD) process. The objective of this work was to reduce the amount of natural gas used for ...steam generation in the plant and the associated greenhouse gas emissions. The INTEGRATION software was used to analyze how heat is being used in the existing design and identify inefficient heat exchanges causing excessive use of energy. Several modifications to improve the base case heat exchanger network (HEN) were identified. The proposed retrofit projects reduced the process heating demands by improving the existing heat recovery system and by recovering waste heat and decreased natural gas consumption in the steam production unit by approximately 40 MW, representing approximately 8% of total consumption. As a result, the amount of glycol used to transfer energy across the facility was also reduced, as well as the electricity consumption related to glycol pumping. It was shown that the proposed heat recovery projects reduced natural gas costs by C$3.8 million/y and greenhouse gas emissions by 61,700 t/y of CO2.
•A heat integration study using Pinch analysis was performed in a SAGD process.•Several modifications are suggested to improve the existing heat recovery system.•Heat recovery projects increased boiler feed water and combustion air temperatures.•The proposed modifications reduced natural gas use for steam generation.•Heat recovery significantly reduced operating costs and greenhouse gas emissions.
This work introduces a novel approach to reduce the energy demand as well as capital and operating costs in a widely used gas purification process by optimal integration of ejector technology. Three ...scenarios for ejector integration have been identified into a dual-stage Selexol™ process configuration for H2S and CO2 removal from syngas. The clean syngas met the requirement to be used in an integrated gasification combined cycle. The intention was to unload or eliminate compressors used in the conventional design, and to reduce the capital and operating costs. Aspen HYSYS® is used to develop a detailed simulation model of the Selexol™ process and to assess the impacts of the proposed design configurations from an energy and economic perspective. A predictive design model is also used to evaluate the operating conditions of the proposed ejectors. Among the scenarios investigated, it is found that ejector integration is attractive only if one or some compressors can be eliminated. This work shows that an optimally integrated ejector in the CO2 recovery and compression section of the Selexol™ process can reduce the capital costs by up to 28%, while reducing the operating costs by up to 6%.
•A dual-stage Selexol™ acid gas removal process from syngas is simulated.•A heat integration analysis is used to optimize the use of energy in the process.•Integration of ejector in the process is investigated for a cost-effective design.•Several scenarios for ejector integration are identified to eliminate compressors.•It is shown that the proposed improvement strategies can reduce the CAPEX and OPEX.
This study focuses on investigating the potential of methane pyrolysis process for low-carbon, low-cost hydrogen production when compared to alternative hydrogen production technologies. The design, ...techno-economic analysis, and GHG emission assessment of two different methane pyrolysis configurations, molten metal-based and thermal plasma-based, are conducted. In addition, to assess the effect of heat sources on both environmental and economic aspects of methane pyrolysis, three heating options are considered for the molten metal-based process: a gas-fired heater, a hydrogen-fired heater, and an electrical heater. Results are then compared against other hydrogen production technologies, including electrolysis, SMR without CCS, SMR with CCS, and biomass gasification. The data required for techno-economic analysis and assessing GHG emissions is obtained from Aspen Plus® process simulation models and U.S. DOE’s H2A Production Models. Our results indicate that the H2 minimum selling price associated with pyrolysis systems are almost always lower than that for SMR with CCS considering a natural gas price of $6/GJ, an electricity price of $0.06/kWh, and a carbon black price of $200/t. However, to achieve a H2 minimum selling price lower than that of SMR without CCS, a carbon black price higher than $500/t is required. Furthermore, the impact of the carbon intensity of the electricity grid and natural gas supply chain for different geographical locations are evaluated. For instance, the results for British Columbia revealed that the GHG emissions of the methane pyrolysis fall within the range of 0.76 and 2.58 kg CO2 eq./kg H2 and can be as low as 50% of that of the SMR with CCS for molten metal-H2 fired configuration. The highest GHG emissions are encountered in the SMR and electrolysis pathways. These analyses show the potential of methane pyrolysis in achieving both lower H2 minimum selling price and GHG emissions, especially when considering solid carbon as a marketable co-product.
•The impacts of system configurations on H2 minimum selling price and GHG emissions of pyrolysis is investigated.•Pyrolysis is compared against electrolysis, SMR without/with CCS, and biomass gasification.•H2 minimum selling price for pyrolysis is almost always lower than that for SMR with CCS.•Pyrolysis has a H2 minimum selling price lower than SMR without CCS when carbon black price is higher than $500/t.•GHG emissions of the methane pyrolysis can be as low as 50% of that of the SMR with CCS.
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