Flowsheet Modifications Research Articles

Increasing final concentrate grade of the Sarcheshmaeh Copper Complex floatation circuit by flowsheet modification

The Sarcheshmeh copper complex flotation circuit of plant No.1 consists of two identical north and south sections where each includes four rougher (each bank consists of 14 cells), two cleaners (each bank consists of 8 cells), two recleaners (each bank consists of 2 cells), and two scavenger banks (each bank consists of 10 cells). The reduction of feed grade along with a change in the mineralogical composition is the main reason of current lower concentrate grade (24%) compared with the design concentrate grade (32%). Because of a lower feed grade, the amount of rougher concentrate has decreased which in turn has significantly reduced the feed rate to the cleaner, recleaner, and scavenger banks. This has increased the mean residence time of the material in the cleaner section resulting in a lower final concentrate grade. A laboratory study showed that the final concentrate grade can be increased by 2-4% if one cleaner stage is added to the flotation circuit. In this research, based on the laboratory results, one cleaning stage was added to the current flotation circuit. In order to make this modification instrumentally possible in the plant, the final concentrate was gravity transported to the Mo-Cu thickeners. This released two pumps and associated tanks which made the addition of one cleaning stage practicable. Finally, a part of the cleaner and scavenger cells was used as the third cleaning stage. This decreased the residence time in the cleaner and scavenger banks. After implementation of one cleaning stage in the south section of the plant, the performance of the circuit compared with the identical north section. It was found that at the same recovery, the concentrate grade of the south section increased by 2.5%. The promising results led to the implementation of adding one cleaning stage in all sections of the flotation circuit.

Cooperative game-based anchor process allocation within sustainable palm oil based complex for environment-food-energy-water nexus evaluation

The challenge in clean palm oil production falls on the management of palm oil mill effluent which is a notable source of greenhouse gas emissions and water pollution. To address these critics against edible palm oil, an integrated palm oil-based complex (POBC) considering effluent elimination and refinery integration is suitable for environmental-food-energy-water (EFEW) nexus development. Optimal retrofit of palm oil mill into EFEW nexus-integrated POBC requires multi-objective considerations to balance the trade-offs between profitability, energy contribution, greenhouse gas, water and land footprints via fuzzy optimisation. With limited practical knowledge, potential flowsheet modifications should be investigated for flexible POBC design. In a cooperative game context, interconnecting processes act as multiple players cooperating to achieve the goal of the game, i.e., POBC performance, where each player has a distinctive impact on the outcome. In this work, such process performance was suggested to be distributed using cooperative game model, to target the EFEW-based anchor process, i.e., the process stage of greatest contribution in the weighted EFEW nexus, for desired flowsheet advancement. Considering these aspects, an integrated fuzzy and cooperative game optimisation framework was developed to identify the anchor process of an EFEW nexus-integrated POBC. EFEW objective-based process performance allocation in the fuzzy optimal POBC was weighted by the decision-maker to allocate the anchor process using developed models and Excel tools. Nut/kernel separation and cogeneration stage is the EFEW-based anchor process in the fuzzy optimal POBC with EFEW nexus score of 41% in this work. A comparative analysis between the proposed method with other approach was done. The favourability of EFEW contributions by POBC in terms of benefit-drawback ratio increased with the percentage of boiler efficiency increment within the targeted anchor process. Targeting anchor process aids planning for process maintenance and advancement to avoid resource wastage on sub-critical processes.

Design and optimization of energy-efficient single mixed refrigerant LNG liquefaction process

The optimal design of single mixed refrigerant (SMR) natural gas liquefaction process is decisive for upgrading the liquefied natural gas (LNG) value chain and can be achieved using process simulators and derivative-free optimization techniques in simulation–optimization frameworks. The process work consumption can be reduced by modifying process flowsheet and manipulating refrigeration cycle thermodynamic conditions and refrigerant composition. The goal of this paper is the design of energy-efficient SMR liquefaction process for LNG production using simulation–optimization approach, in Aspen HYSYS® and MATLAB®, that considers more decision variables to be optimized with a Nelder–Mead simplex algorithm and small flowsheet modifications, such as hydraulic turbines and flash separators in between compression stages. The present approach resulted in liquefaction process with network duty of 750.2 kJ per kg of natural gas, which is considerably smaller than those reported in the literature.

Ammonia-based CO2 capture parameters optimization and analysis of lean and rich vapor compression processes

Carbon dioxide (CO2) capture through chemical solvent absorption process is the most favourable and well-proven technique to reduce CO2 emission. However, in this technique, the energy penalty correlated with absorbent regeneration is a critical challenge. To reduce energy consumption, the operating parameters in NH3-based CO2 capture process were optimized. Then flowsheet modifications including rich vapor compression (RVC) and lean vapor compression (LVC) were proposed for the first time in the NH3-based CO2 capture process. Both the LVC and RVC schemes were combined with cold solvent split (CSS) process to further reduce the energy requirements. Moreover, the LVC and RVC processes of this study were also compared with the advanced NH3-based and MEA-based LVC and RVC processes with respect to energy reduction. The optimized process was considered as a base process and it was compared with the modified processes. The RVC and LVC combined with CSS process reduced the reboiler duty by 26.7% and 19%, respectively. These energy savings are much higher than that of 11.6% and 8.26% energy savings of the advanced NH3-based rich split and inter-heating processes, respectively. The total equivalent energy savings of LVC, RVC, LVC with CSS, and RVC with CSS processes in this study were about 6.4%, 18.1%, 3.4%, and 15%, respectively, which are higher than 3.4% and 8.5% energy savings of MEA-based LVC with CSS and RVC with CSS processes, respectively. Furthermore, these combined processes can also avoid the use of a condenser.

Process development unit experimental studies of a split‐flow modification for the post‐combustion CO2 capture process

AbstractA process development unit (PDU) for amine‐based post‐combustion carbon capture located at Clean Coal Technologies Centre in Zabrze, Poland, was used to validate split‐stream configuration. A PDU having capacity up to 100 m3n/h was designed to test the amine scrubbing carbon capture process from flue gases or mixtures of technical gases. Flexible process flow sheet of the unit allowed investigation of the split flow process.The split‐flow flowsheet modification was compared with a standard system for chemical absorption‐based CO2 capture. The tests were conducted using well‐accepted baseline solvent: 30 wt% aqueous monoethanolamine solution. The flow sheet modification resulted in a decrease of reboiler heat duty by ~1.6% and an increase in CO2 recovery by ~1.2 p.p. Split‐flow process modification was examined together with standard process flow sheet, and vast number of process parameters recorded during the trials have been presented. The explanation of beneficial effects of split‐flow designs have been shown together with detailed analysis of experimental trials carried out using PDU for amine‐based post‐combustion carbon capture. This paper is also a valuable source of experimental data useful during validation of models. Copyright © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

Upgrading the integration of supercritical coal-fired power plant with post-combustion CO<SUB align="right">2 capture process through process simulation

The purpose of this study is to alleviate the negative effect of post-combustion CO2 capture (PCC) process on the generating efficiency of a 600 MWe supercritical coal-fired power plant (CFPP) through modelling and simulation. Steady state models for a 600 MWe supercritical CFPP and a MEA-based PCC plant with corresponding compression unit were developed and integrated in Aspen Plus. In the two basic cases with steam extracted from different locations, efficiency penalty of 14.48% points and 11.89% points were caused, respectively. Subsequently, four steps were taken to improve the overall performance of the integrated process, which involves: 1) waste heat recovery; 2) throttling loss reduction; 3) capture flowsheet modification and 4) temperature difference narrowing. From the final simulation results, the efficiency penalty is reduced to 8.07% points. This study indicates that appropriate flowsheet modifications for the integrated process can significantly improve the overall energy efficiency.

Upgrading the integration of supercritical coal-fired power plant with post-combustion CO<SUB align="right">2 capture process through process simulation

The purpose of this study is to alleviate the negative effect of post-combustion CO2 capture (PCC) process on the generating efficiency of a 600 MWe supercritical coal-fired power plant (CFPP) through modelling and simulation. Steady state models for a 600 MWe supercritical CFPP and a MEA-based PCC plant with corresponding compression unit were developed and integrated in Aspen Plus. In the two basic cases with steam extracted from different locations, efficiency penalty of 14.48% points and 11.89% points were caused, respectively. Subsequently, four steps were taken to improve the overall performance of the integrated process, which involves: 1) waste heat recovery; 2) throttling loss reduction; 3) capture flowsheet modification and 4) temperature difference narrowing. From the final simulation results, the efficiency penalty is reduced to 8.07% points. This study indicates that appropriate flowsheet modifications for the integrated process can significantly improve the overall energy efficiency.

Systematic study of aqueous monoethanolamine (MEA)-based CO2 capture process: Techno-economic assessment of the MEA process and its improvements

The present study investigated the technical and economic performance of the monoethanolamine (MEA)-based post-combustion capture process and its improvements integrated with a 650-MW coal-fired power station. A rigorous, rate-based model developed in Aspen Plus® was employed to evaluate technical performance, while a comprehensive economic model was used to determine the required capital investment and evaluate economic performance. The techno-economic model was validated with published cost results. Our estimation of the capital investment for the baseline MEA capture plant was US$1357/kW, with a CO2 avoided cost of US$86.4/tonne. We then proposed process improvements such as parameter optimisation, lean/rich heat exchanger optimisation and flow sheet modifications to improve energy and cost performance. The combined process improvements reduced the capital investment by US$72/kW (a 5.3% saving) while cutting overall energy consumption by 24.5MW/h (a 13.5% reduction). As a result, the CO2 avoided cost fell to $75.1/tonne CO2, a saving of US$11.3/tonne CO2 compared with the baseline. Lastly, we performed a sensitivity study and cost breakdown analysis to understand how the CO2 avoided cost would be apportioned to the economic and technical parameters. The results indicate the directions of technical development to further improve the economic viability of the CO2 capture process.

Simulation-Assisted Evaluation of Grinding Circuit Flowsheet Design Alternatives: Aghdarreh Gold Ore Processing Plant / Ocena Alternatywnych Schematów Technologicznych Procesu Rozdrabniania W Zakładach Przeróbki Rud Złota W Aghdarreh, Z Wykorzystaniem Metod Symulacji

Abstract The run of mine ore from Aghdarreh gold mine must be comminuted to achieve the desired degree of liberation of gold particles. Currently, comminution circuits include a single-stage crushing using a jaw crusher and a single-stage grinding using a Semi-Autogenous Grinding (SAG) mill in closed circuit with a hydrocyclone package. The gold extraction is done by leaching process using cyanidation method through a series of stirred tanks. In this research, an optimization study of Aghdarreh plant grinding circuit performance was done to lower the product particle size (P80) from 70 μm to approximately 40 μm by maintaining current throughput using modeling and simulation approach. After two sampling campaigns from grinding circuit, particle size distribution data were balanced using NorBal software. The first and second data sets obtained from the two sampling campaigns were used to calibrate necessary models and validate them prior to performing simulation trials using MODSIM software. Computer simulations were performed to assess performance of two proposed new circuit flowsheets. The first proposed flowsheet consists of existing SAG mill circuit and a new proposed ball mill in closed circuit with a new second hydrocyclone package. The second proposed flowsheet consists of existing SAG mill circuit followed by a new proposed ball mill in closed circuit with the existing hydrocyclone package. In all simulations, SAGT, CYCL and MILL models were selected to simulate SAG mill, Hydrocyclone packages and ball mill units. SAGT and MILL models both are based on population balance model of grinding process. CYCL model is based on Plitt’s empirical model of classification process in hydrocyclone units. It was shown that P80 can be reduced to about 40 μm and 42 μm for the first and second proposed circuits, respectively. Based on capital and operational costs, it can be concluded that the second proposed circuit is a more suitable option for plant grinding flowsheet modification.

Pilot plant results for advanced CO2 capture process using amine scrubbing at the Jaworzno II Power Plant in Poland

The purpose of this study is to present the testing of a 30wt% solution of ethanolamine (MEA) in an advanced CO2 capture pilot plant. The mobile pilot plant, designed, constructed and operated by the Institute for Chemical Processing of Coal (IChPW) in cooperation with industrial partners: TAURON Polska Energia and TAURON Wytwarzanie, was used to carry out trials at the Jaworzno II Power Plant in Poland. Thanks to flexible technological design, numerous process flows sheet modifications were tested. The use of split flow or inter-stage absorber cooling is demonstrated and compared to the standard amine process. Presented modifications resulted in an increase of CO2 recovery ranging from 3% to 8%, whilst reducing the reboiler heat duty by about 5%. The correlation of CO2 recovery, reboiler heat duty and process parameters (solvent loading, L/G ratio) has been established for numerous process flow sheet modifications.The tests provide valuable experimental evidence for modifications described in the literature, mainly through modelling and demonstrate that flow sheet modifications, despite the increase in plant complexity, are worth considering.

Energetic Evaluation of Different Flow Sheet Modifications of Post-Combustion CO2 Capture Plant at Coal and Natural Gas Fired Power Plant for a Generic Improved Solvent

Abstract The post-combustion capture (PCC) technology is a promising possibility to reduce CO 2 emissions of fossil fuel fired power plants. One of the main concerns for the PCC is the loss in electric power output. A reduction in efficiency penalty for solvent based PCC can be achieved by improving the solvent properties as well as by improving the process design. There are many different process flow sheet modifications with an improvement in process design reported in literature. In this work two of these modifications for a capture plant are evaluated. To be able to compare these process modifications it is necessary to evaluate them on identical solvent and process conditions. The modified processes are compared to base cases processing the flue gas from a supercritical pulverised coal fired power plant as well as a natural gas combined cycle power plant. The solvent used in the capture plant is a generic improved solvent, representing possible future solvents. The main advantages of the flow sheet modifications are pointed out. Subsequent, the specific reboiler heat duty, the specific cooling duty and the specific auxiliary power for the capture plant are shown for the flow sheet modifications. The overall efficiency penalties for the flow sheet modifications are compared and differences are highlighted.

Advanced CO2 Capture Pilot Plant at Tauron's coal-fired Power Plant: Initial Results and Further Opportunities

Abstract Institute for Chemical Processing of Coal in cooperation with industrial partners: TAURON Polska Energia S.A. and TAURON Wytwarzanie S.A. designed, constructed and operated pilot plant at Łaziska Power Plant in Łaziska Gorne, Poland. The carbon capture facility is based on amine post-combustion process technology and used 30 wt% aqueous ethanolamine solvent. Approximately 1000 kilograms of CO 2 can be captured per day from flue gas stream of 200 m 3 /h of a 225MWe hard coal fired boiler. The plant captured its first tonne of CO 2 in August 2013. The purpose of this study is to present initial results from tests carried out at Łaziska Power Plant using different process flow sheets: heat-integrated stripping column and split flow process. The tests provide valuable experimental evidence for modifications described in the literature, mainly through modelling and demonstrate that flow sheet modifications, despite the increase in plant complexity, are worth to consider.

Mass Balance and Quantitative Mineralogy Studies for Circuit Modification

Two plant surveys were conducted at Lahanos Cu--Zn Concentrator under different operating conditions to assess the performance of the plant. In particular, an alternative process flowsheet, which was based on metal balance and quantitative mineralogy, was evaluated. First, a block survey was performed in the existing circuit. Next, cell-by-cell sampling was performed in the Cu rougher bank after the circulation of the scavenger concentrate to the feed was stopped. This allowed for the determination of the flotation kinetics of the minerals in the fresh feed and the effect of the circulation on the stream. Mass balancing results revealed that 14.3% and 12% of the copper was lost by the rougher and scavenger tails, respectively. Mineralogical analysis of the first survey showed that the scavenger concentrate primarily consisted of coarse/locked particles. According to the results, even the amounts of minerals in the rougher concentrates were similar in both surveys; liberation has improved by approximately 35–69% in the second survey particularly for copper minerals. It is concluded that recirculating the stream to the feed would negatively affect plant performance. Therefore, finer grinding was tested in the plant to assess the effect of decreasing feed tonnage on the liberation. It was found that copper loss in the tails was significantly decreased. Finally, possible flowsheet modifications based on these results are discussed.

Hydrogen amplification from coke oven gas using a CO2 adsorption enhanced hydrogen amplification reactor

To improve coke oven gas (COG) energy conversion, alternative configurations for amplifying hydrogen from COG are proposed in this paper. In these new configurations, a CO2 adsorption enhanced hydrogen amplification reactor is combined with a pressure swing adsorption separation unit (PSA) to produce pure hydrogen. Hydrogen production was integrated with desorption gas utilization, in situ CO2 capture and waste heat recovery to improve COG energy conversion efficiency and decrease CO2 emissions. To analyze the advantages of the flowsheet modifications, technical and economic performance indicators were used to evaluate and compare the performances of the various system configurations. Simulation results show that the alternative configurations proposed in this paper have higher energy conversion efficiencies, higher hydrogen yields and shorter dynamic payback periods. The variation of technical performance with reaction temperature, pressure, sorbent to carbon ratio and steam to carbon ratio were also analyzed using a sensitivity study. Optimal operating conditions for the CO2 adsorption enhanced hydrogen amplification reactor were obtained based on the simulation results.

Screening of flowsheet modifications for an efficient monoethanolamine (MEA) based post-combustion CO2 capture

The purpose of this study is to assess and compare most of the CO2 capture unit flowsheet modifications described in the literature through modelling. The main component of the process, absorber and stripper were specifically modelled around a rate based model with mass transfer and chemical kinetics. The solvent used for the study is monoethanolamine (MEA). The different case studies are compared to a reference case presenting a standard good performance in term of energy consumption (3.7 GJ/tCO2 at 1atm). Their impact on the thermal power plant is also briefly studied in order to permit the performances comparison in term of plant efficiency (electric power output/coal lower heating value).The best individual simple modifications are: a stripper operating with moderate vaccum pressure (around 0.75bar), the staged feed of the stripper, the lean solvent vapour compression, the overhead stripper compression. They allow a decrease of efficiency penalty by 4–8%. Some other modifications contribute to the good performance of the process such as: intercooler, improved economizer, boiler condensate vapour compression, with a reduction of efficiency penalty around 2%. These individual modifications can be combined in order to build very efficient process with efficiency penalties reduction ranging from 10% to 25%. Finally, some drastic process modifications can improve very significantly the process performance such as: advanced split-flow with a reduction of efficiency penalty by around 30% or direct steam stripping with a reduction of efficiency penalty of 27%.A qualitative summary of one to one interaction between process modifications is proposed. These process modifications must be coupled with new solvents and innovative power plant heat integration strategies in order to show the true potential of the amine-based post-combustion capture processes.

Exergy analysis and flowsheet modification of PT. PUSRI II Palembang's reformer unit for the production of synthesis gas from natural gas

AbstractSeveral processes which produce synthesis gas from natural gas have been analyzed by the exergy method. To minimize the exergy losses associated to chemical reaction, it is important to manage the exergy losses through the analysis, reconsidering the chemical path. A generally applicable and schematic way of performing exergy analysis and dealing with their results are illustrated. It is integrated to the modified flowsheeting reformer. As petrochemical industry in Indonesia, PT. Pupuk Sriwijaya II Palembang uses natural gas as a raw material to produce synthesis gas through the primary and the secondary reformers in a series. In the modified flowsheeting reformer, partial oxidation process has been added before the primary reformer and the secondary reformer has been eliminated from the process pathways. The exergy method of analysis has been implemented for each process, in order to calculate the exergies of the material streams along with the energy and mass‐balance calculations both in the modified flowsheeting reformer and in a series process of the primary and the secondary reformers. And, the results of the calculations of the modified flowsheeting reformer in the process proposed modification are then compared to the results of the calculations of the series process of reformers in the existing conventional process. From the analysis, the overall exergy losses in a series process of the primary and secondary reformers can be reduced until 61.33%, by applying the modified flowsheeting reformer. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.

Preliminary analysis of process flow sheet modifications for energy efficient CO 2 capture from flue gases using chemical absorption

The energy penalty associated with solvent based capture of CO 2 from power station flue gases can be reduced by incorporating process flow sheet modifications into the standard process. A review of modifications suggested in the open and patent literature identified several options, primarily intended for use in the gas processing industry. It was not immediately clear whether these options would have the same benefits when applied to CO 2 capture from near atmospheric pressure combustion flue gases. Process flow sheet modifications, including split flow, rich split, vapour recompression, and inter-stage cooling, were therefore modelled using a commercial rate-based simulation package. The models were completed for a Queensland (Australia) based pilot plant running on 30% MEA as the solvent. The preliminary modelling results showed considerable benefits in reducing the energy penalty of capturing CO 2 from combustion flue gases. Further work will focus on optimising and validating the most relevant process flow sheet modifications in a pilot plant.

Optimization of MEA based post combustion CO2 capture process: Flowsheeting and energetic integration

Abstract The main limitation of post-combustion CO 2 capture technology is the high energy consumption leading to a power output loss of approximately 25% when coupled with CO 2 compression. Studies to break this limitation follow two main paths: formulation of new solvents and optimization of the process flowsheet. The purpose of this works is to assess the impact of the different flowsheet modifications and power plant integration on the plant performance. CO 2 capture amine plant has been integrated in a gross electrical 1200 MWe supercritical coal-fired power plant; a process optimization study coupled with economical and availability analysis has been performed for each studied case and compared to a reference case: standard amine capture process with 30%wt MEA. The capture plant increases the cost of a new power plant by approximately 70% and the electricity price by 45%. Process flowsheet optimization on the amine capture plant do no significantly increase the specific power plant cost (from 0 to 2%) with CO 2 capture, the additional expenditure are compensated with the plant efficiency gains. The cost of electricity is, also, almost not affected by the flowsheet optimization (from −2.5 to +1.5%). The best tested configuration allows a reduction of 10% of the cost of avoided CO 2 . The addition of a capture plant increases by approximately 1.4%pt the risk of forced outage factor and therefore decreases the whole power plant availability by the same value. The effects of the availability decreases due to the capture plant on CO 2 and electricity prices are negligible. This work shows that these modifications alone are not sufficient to enable an economically feasible carbon capture on coal fired power plant despites a loss of efficiency of approximately 10%pt. The goal of less than 5%pt efficiency losses induced by post combustion carbon capture need a combination of new solvent and optimized process or a totally new breakthrough process.

Analysis of combined process flow sheet modifications for energy efficient CO2 capture from flue gases using chemical absorption

Abstract The energy penalty associated with solvent absorption based Post Combustion CO 2 Capture is one of the main stumbling blocks for the implementation of this technology into new and existing fossil-fired power stations. Modifying the flow sheet of the standard chemical absorption process can allow for reductions in the energy and resource usage of such plants. A review of the open and patented literature highlighted modifications, predominantly related to applications in the gas processing industry. These modifications were modelled using commercially available rate based simulation software. This allowed the expected energy consumption of a CO 2 capture pilot plant, based in Australia, to be estimated. The modelling results pointed towards the optimal conditions for each modification. Selected modifications were then added together to determine whether any synergistic effects could be observed. The split flow process was found to have one of the highest energy savings (reduction in reboiler duty) over the reference plant. Adding inter-cooling on the absorber column with splitting of the rich solvent stream entering the stripping column showed a reduction in reboiler duty slightly greater than anticipated based on the results of the individual modifications.

Miniature DIAMEX processes in a hollow fibre module micro-plant: process development and optimisation

A hollow fibre module (HFM) micro-plant was built to perform continuous liquid-liquid extraction tests with very small feed volumes, using miniature HFM as phase contactors. Spiked DIAMEX tests (i.e., co-extraction of americium, curium, and lanthanides from PUREX raffinate) were performed in this plant. Following some flow sheet modifications, raffinate decontamination factors of up to 30000 and 900 were achieved for americium and curium, respectively.