Bottom Stage Research Articles

From circular to square‐based section spouted beds: Scale‐up and design overview of a multistage thermal unit

AbstractThis work summarizes the results of several research projects to demonstrate the possibility of scaling‐up spouted beds by assembling a number of square‐based jet units. Cylindrical vessels with a bottom cone and parallelepiped ones with a frustum base do not differ to a large extent in terms of hydrodynamic features. The existing correlations can be used to predict these square‐based spouted beds. Spouted beds can be very reasonably described as well‐mixed reactors. By assembling several units, it is possible to approach a plug flow state for solids residence time distribution (RTD) in continuous processes. Spouting stability is fully reached when the modules do not interfere each other: this goal is obtained by positioning the downstream units at a certain lower level and having the solids move by overflow; placing internal vertical baffles between contiguous units is the solution. Two hydrodynamical models are proposed to describe single and multiple spouted beds; their predictions help in choosing the best geometrical configuration for the assemblage. A possible application of a multiple spouted bed reactor was envisaged for gasifying pelletized textile residues to generate syngas which can be directly used in situ as a co‐fuel. Two units were built: a single 0.2 m side square‐based spouted bed furnace and the consequent dual stage scale‐up apparatus suitable for an auto thermal process. In the bottom stage, four units work independently to run combustion/gasification of low‐quality solid residues, while the upper stage had a cascade of four modules to run pyrolysis/gasification of selected biomass and obtain valuable secondary products.

Full-scale investigations of initial deposits formation in a cement plant co-fired with coal and SRF

This work investigates the initial (short-term) deposit formation in a cement calciner co-fired with coal and SRF (Solid Recovered Fuel). The main objective was to evaluate and compare the tendencies of deposit formation (i.e. material deposition rate and composition) at different locations (heights) in the calciner system, during different operation conditions. A steel probe was used to collect initial deposits from four different sampling locations: i) in the kiln riser (two sampling locations), ii) in the mid calciner, and, iii) at the outlet from the bottom stage preheater cyclone (C5). After an exposure time of the probe between 1 and 20 min, the collected deposit samples were weighted and characterized by SEM-EDX, ICP-OES/IC, and XRD. Plant operation data, measured gas temperatures, as well as gas phase composition data (i.e. KCl(g) and SO2(g)), supported the evaluation of deposit formation. Due to high particle flux (up to approx. 61,000 kg/(m2·h) in the riser duct), the average net deposit formation rate was around 500 kg/(m2·h) for 1 min exposure time, decreasing to <100 kg/(m2·h) for exposure times ≥4 min (due to spontaneous shedding and erosion). The deposits contained primarily five crystalline phases (CaO, CaCO3, Ca(OH)2, KCl, and SiO2), which is in general consistence with the composition of the admitted preheated raw meal (C4 meal) at measurement locations, with a slight enrichment in KCl, suggesting some condensation of volatile elements from the high-temperature gas phase on the surface of the somewhat colder deposit particles. Further, the deposit samples obtained in the kiln riser had a higher degree of calcination (higher proportion of CaO as compared to CaCO3) as compared to the admitted C4 meal, suggesting carry-over of dust from the kiln feed pipe, or fast calcination of the riser meal due to high temperature.The collected short-term deposits differ significantly from long-term (mature) deposits, which have previously been collected from the site, in terms of chemical and physical properties. Compared to short-term deposits, which had a content of KCl in the range of approx. 3–5 wt%, the content of KCl in the mature deposits increased substantially from around 2 wt% in samples from the kiln riser area to a level of >20 wt% in the calciner and C5 cyclone area, implying significant accumulation of KCl caused by volatile circulation and condensation from the hot gas on surfaces with locally lower temperatures. The most prevalent crystalline phases in the mature deposits were KCl, CaCO3, and the mineral spurrite (Ca5(SiO4)2CO3). The presence of spurrite implied that SiO2 reacts with CaCO3, or with CaO and gaseous CO2, to form spurrite during long-term deposit build-up and maturation.Overall, the results from this work suggest that the short-term deposit formation in the cement calciner is dominated by impaction. The composition of the short-term deposits is quite similar to the composition of the entrained C4 meal particles; while the build-up of mature deposits is influenced greatly by local temperature gradients and long-term fluctuations. I.e. in zones with locally lower temperatures, such as cold area of calciner walls (< ∼850 °C), heterogeneous condensation and/or thermophoresis of KCl from the high-temperature flue gas is facilitated.

Magnetic Cooling and Vibration Isolation of a Sub-kHz Mechanical Resonator

We report recent progress toward the realization of a sub-mK, low-vibration environment at the bottom stage of a dry dilution refrigerator for use in mechanical tests of quantum mechanics. Using adiabatic nuclear demagnetization, we have cooled a silicon cantilever force sensor to Tapprox 1 mK. The temperature of the tip holder of the cantilever chip was determined via a primary magnetic flux noise thermometer. The quality factor of the cantilever continues to increase with decreasing temperature, reaching Qapprox 4cdot 10^4 at 2 mK. To demonstrate that the vibration isolation is not compromised, we report the detection of the thermal motion of the cantilever down to T approx 20 mK, only limited by the coupling to the SQUID readout circuit. We discuss feasible improvements that will allow us to probe unexplored regions of the parameter space of continuous spontaneous localization models.

Separation and purification of enveloped and non-enveloped viruses from water samples using an aqueous two-phase system

In this study, a new strategy for enriching viruses in water was developed to improve the detection of viruses in environmental samples. The virus was enriched from water by aqueous two-phase system (ATPS), and the recovery and purification were characterized by tissue culture median infection dose (TCID50) and total protein removal rate. The isolation and purification methods of envelope virus (H1N1) and non-envelope virus (human adenovirus type 5, HAdV-5E) were established and optimized. The results of ATPS were compared with those of membrane filtration, polyethylene glycol precipitation and ultrafiltration. Using ATPS, both viruses were enriched in interphase due to the combined action of volume exclusion and bottom stage salting out. Under the optimum conditions, the recoveries of H1N1 and HAdV-5E were 94.87 ± 2.37% and 96.22 ± 4.71% respectively, and the total protein removal rates were 43.02 ± 5.21% and 71.01 ± 6.34% respectively. Compared with conventional methods, ATPS showed superior performance in recovering virus content and water volume, and the average recoveries were 94.06% (H1N1) and 90.07% (HAdV-5E). Therefore, ATPS had superiorities of high recovery, simple operation and maintaining virus particle activity(Fig. 1).

Power Flows and Losses Calculation in Radial Networks by Representing the Network Topology in the Hierarchical Structure Form

This paper proposes a structured hierarchical-multilevel approach to calculating the power flows and losses of electricity in radial electrical networks with different nominal voltages at given loads and voltages of the power source. The researched electrical networks are characterized by high dimensionality, dynamism of development, but also insufficient completeness and reliability of state information. The approach is based on the representation of the initial network graph in the form of a hierarchical-multilevel structure, divided into two stages with rated voltages Unom≤35 kV and Unom≥35 kV, and using the traditional (manual) engineering two-stage method, where the calculation is performed in a sequence from bottom to top (stage 1) and from top to bottom (stage 2), moving along the structure of the network. The application of the above approach makes it possible to obtain an algorithm for implementation on a computer, which is characterized by universality (for an arbitrary configuration and complexity of the network), high performance and low requirements for the computer memory.

SRInpaintor: When Super-Resolution Meets Transformer for Image Inpainting

Recent image inpainting methods have achieved remarkable improvements by using generative adversarial networks (GAN). Most of them have been designed to produce plausible results from high-level semantic features using only high-resolution (HR) supervision. However, because abundant details are lost in large holes, it is difficult to simultaneously synthesize details while preserving structural coherence in HR space. Besides, the correlations between the inside and outside of the missing region play a critical role in transferring relevant known information to generate semantic-coherent textures, especially in patch matching-based methods. In this work, we present SRInpaintor which inherits the merits of super-resolution (SR) and transformer for high-fidelity image inpainting. The SRInpaintor starts from global structure reasoning with low-resolution (LR) input and progressively refines the local textures in HR space, constituting a multi-stage framework with SR supervision. The bottom stage recovers coarse SR results that provide structural information as an appearance prior, and is combined with the higher-resolution corrupted image at the next stage to render available textures for the missing region. Such a design can analyse the image from LR to HR with the increase of stages, enabling coarse-to-fine information propagation and detail refinement. In addition, we propose a hierarchical transformer (HieFormer) to model the long-term correlations between distant contexts and holes. By embedding it into a compact latent space in a cross-scale manner, we can ensure reliable relevant texture transformation and robust appearance consistency. Experimental results demonstrate the superiority of our method compared with recent state-of-the-art methods. Code will be available on <uri>https://github.com/lifengshiwo/SRInpaintor</uri>.

Coordinated operation strategy of distribution network with the multi-station integrated system considering the risk of controllable resources

The rapid growth of distributed energy resources (DERs) has significantly increased the demand for land resources and power delivery equipment in urban areas. The construction of a multi-station integrated system in the substation area could settle this challenge well. However, its integration will reshape the power flows of urban distribution systems. The approach to reasonably coordinate distributed resources of integrated stations and power supply districts challenges the traditional operation management. In this paper, we explore the capability of the integrated station to join distribution system operation, and collaborate with DERs in its power supply zone to mitigate operational risks. A three-stage operation strategy is proposed for this purpose, considering the adjustable potential of DERs, which would affect reliability performance. The upper stage schedules the integrated station and other DERs. The middle stage coordinates the internal resources of the integrated station and evaluates its equivalent adjustable potential, while the bottom stage would measure the resource regulatory risk to adjust the schedules. OLTC transformer, PVs, BES and flexible loads are coordinated. Finally, the proposed method is validated in a modified PG&E 69-node test system. The results show the effectiveness of the management strategy of the integrated station to grid (S2G), and the voltage/loading violation of the distribution network are mitigated.

Hierarchical Fusion Process of Destination Image Formation: Targeting on Urban Tourism Destination

Image has been widely accepted as a combination of perceived elements that are commonly discrete and static ones. ‘Discrete’ means that the elements are treated as separate ones with each other, with no interactions among them. ‘Static’ means that the elements would not be changed into other forms in the process of destination image formation. This study, thinking outside the box, tries to explore destination image formation through perceived elements and take their interactions and corresponding changes into account. Machine learning, as the core of artificial intelligence, is applied for data analysis in this study. Urban tourism destinations are targeted because of their variety and abundance of perceived elements. Data are collected from both interview and questionnaire surveys of tourists. Through several phases of analysis, this study finally finds that perceived elements do interact with each other and change into new forms level by level in tourism destination image formation. Specifically, there are four levels from bottom to top in the whole process of destination image formation, i.e., the individual-landscape layer, compound-atmosphere layer, dual-factor layer, and overall-image layer. In the bottom stage, elements are commonly numerous, separate, and concrete. With the interactive effects of the elements, they integrate with each other and generate some new forms in higher levels, which would be more general and abstract. Based on the findings, the dynamic fusion process and pyramid hierarchy of destination image formation are disclosed. This study explores destination image formation from a new perspective, considering perceived elements within a dynamic, synthetic system, and therefore provides practical insights into destination image construction in a more comprehensive and targeted way.

Methanol–Water Purification Control Using Multi-Loop PI Controllers Based on Linear Set Point and Disturbance Models

Dimethyl ether (DME), derived from methanol, has been issued as an alternative to diesel and LPG. This study will continue the research of an optimized process control design for DME purification plants, specifically the methanol purification process. This way, water can be separated, and the main product, methanol, can be recycled for DME synthesis. A setpoint-based linear model of a methanol–water purification system has been developed with four controlled variables (CV) with objectives to; maintain a separated liquid water stream in the bottom stage (Stage 30) of the distillation column for methanol–water separation at 11.22%, keep the purified liquid methanol at a condenser at 58.81 °C and 49.96% of level, and the last CV is the cooler in the distillate stream, to keep the purified methanol’s top product at 40.75 °C. To complete the model, a first order plus dead time (FOPDT) disturbance model is created against the inlet temperature and flow rate of the feed, the major cause of disturbances in the industry. Using a traditional proportional integral controller connected to each controlled variable, a multi-loop control system is formed with optimization and compared to the disturbance rejection of multivariable model predictive control (MMPC). The final improvement against the feed temperature and flow for CV1, CV2, CV3, and CV4 is shown by, respectively, Integral Absolute Error (IAE) values of 79.49%, 99.90%, 100%, and 99.99% and Integral Square Error (ISE) values of 97.1%, 100%, 99.99%, and 100%.

Seeding the drainage canal of a wastewater treatment system for the natural rubber industry with rubber for the enhanced removal of organic matter and nitrogen

Current pretreatment methods for wastewater from natural rubber (NR) factories either have low rubber recovery efficiency or are costly to operate. A wastewater treatment system was developed that combines a pretreatment canal (PTC) seeded with rubber, an anaerobic baffled reactor (ABR), and a down-flow hanging sponge (DHS) reactor. The PTC is simple to implement and contributes to not only rubber recovery but also organic matter removal in the ABR and nitrogen removal in the DHS reactor. In experiments, the PTC recovered 16.6% of residual rubber through coagulation. The ABR increased the chemical oxygen demand removal efficiency and methane recovery compared with other anaerobic reactors treating raw NR wastewater. The DHS reactor removed 30.7% of total inorganic nitrogen (TIN) by nitrification, anaerobic ammonia oxidation and denitrification. Feeding the bottom stage of the DHS reactor with sodium acetate solution increased the TIN removal efficiency to 87.8%. The water quality of the final effluent achieved the Vietnamese standards for the NR industry. Microbial community analysis was performed to identify the dominant microorganisms and mechanisms in the PTC, ABR, and DHS reactor.

Stress sensitivity evaluation of ultra-low permeability sandstone reservoir and its influence on oilfield development

Luohe ultra-low permeability sandstone reservoir is a hot block in Yanchang oilfield, which is a potential point for increasing production and reservoir. In view of the current situation that there is no unified stress sensitivity evaluation standard for ultra-low permeability sandstone in the study area, taking the ultra-low permeability sandstone in Luohe district as the research object, the stress sensitivity evaluation of ultra-low permeability sandstone is carried out by using experimental analysis as the main means. The results show that it is more accurate to evaluate porosity by using pore stress sensitivity coefficient instead of pore compressibility coefficient. With the increase of net overburden pressure, the porosity stress sensitivity decreases gradually; the permeability stress sensitivity is evaluated by variable confining pressure. With the increase of confining pressure, the permeability damage decreases. With the decrease of confining pressure, the permeability damage increases, but it can not recover to the original value, so the permeability damage is irreversible; in the low bottom hole pressure stage, stress sensitivity has a greater impact on oil well productivity, while in the high bottom hole pressure stage, stress sensitivity has a smaller impact on oil well productivity; advanced water injection can reduce the adverse effect of stress sensitivity on the development of ultra-low permeability sandstone and maximize the economic benefits. The research results clarify the method of stress sensitivity evaluation, and provide guidance for efficient water injection in the next step.

A New Hybocrinid Genus (Echinodermata, Crinoidea) from the Middle Ordovician of Ladoga Glint on the Volkhov River

The hybocrinid crinoid Trecrinus schmidti gen. et sp. nov. is described from the Middle Ordovician (Uhaku Regional Stage, Darriwilian) of the lower reaches of the Volkhov River. Three long arms in the A, D and C radii, and a low cup with a flattened base without a stem are the main characteristics of the new genus. Morphology of the new genus emphasizes the similarities and differences in the morphogenetic capabilities of the hybocrinid lineages, which simultaneously developed on the Baltica and Laurentia paleocontinents, separated from each other in Ordovician. In the pronounced tiering of the Valim benthic community, this new genus occupied the lowest bottom stage.

Design of nanofiltration cascades for fructooligosaccharides using the McCabe-Thiele approach

We developed a design method for an inhomogeneous membrane cascade by adopting the McCabe-Thiele method, which is long established for designing distillation columns. The stage cut value is an independent design parameter in the design procedure and thus has to be set. Within each section, the operating conditions were uniform, but both sections could be operated differently using various combinations of membranes, trans-membrane pressure, temperature and stage cut. The procedure was applied to cascaded nanofiltration for the fractionation of a mixture of fructooligosaccharides of varying molecular weight. The stage and area requirements were strongly dependent on the initial design parameter, the overall stage cut. The total area was related to the overall system cut. However, the overall system cut was dependent on the stage cuts for both sections (top and bottom). The top stage cut could be chosen, whereas the bottom stage cut needed to be calculated iteratively to match the top design at the intersection.

Design optimization of a 3-stage membrane cascade for oligosaccharides purification using mixed integer non-linear programming

Inhomogeneous membrane cascade systems have been utilized to purify fructooligosaccharides (FOS). Such a process allows a different setup at every stage of the cascade. Varying the setup at every stage implies an optimization problem related to the selection of the membrane and combinations of operating conditions. This paper solves the optimization problem for an inhomogeneous 3-stage membrane cascade and uses the solution as a design guideline. The optimization problem in the 3-stage membrane cascade design has been formulated as a mixed integer, non-linear programming model and solved using the global optimization solver, BARON. By maximizing the yield repetitively with varying purity requirements, a frontier curve has been constructed. The frontier curve was mapped showing the window of operation. The map guides towards the setup that promotes higher permeation in the feed stage when we switch from high yield to high purity. On the other hand, the setup selection at the bottom stage does not show a clear switch, which indicates that the selection at this stage is less critical.

Prospect of solar-driven ejector-compression hybrid refrigeration system with low GWP refrigerants in summer of Guangzhou and Beijing

Abstract In this paper, the prospect of low-GWP refrigerants used in solar-driven ejector-compression hybrid refrigeration system was analyzed and evaluated based on the solar radiation data in summer of Beijing and Guangzhou. Prominent environmental friendly alternative refrigerants, including HCFO-1233zd(E), HFO-1336mzz(Z), HFO-1234ze(Z), HCFO-1224yd(Z) and HC-600 were chosen as the working fluids to address the environmental concerns, while HFC-245fa was used as the baseline refrigerant. The hybrid refrigeration system composed of an ejector refrigeration system as the upper stage and a vapor compression system as the bottom stage, respectively. The results indicated that the system with HFO-1234ze(Z) showed the highest COP. HFO-1234ze(Z) was followed by HCFO-1233zd(E) and HC-600, and all of them showed higher COP than that of HFC-245fa. The system with HC-600 needed more electric energy than any other systems, while HFO-1336mzz(Z) consumed the lowest electric power. Meanwhile, the performances of HFO-1234ze(Z) and HFC-245fa systems were further compared. It was found that for both working fluids, the heat load of the condenser (Qe,c), total electric energy consumption (We) and electric energy of compressor (Wcom) in August were the highest in Beijing, while in Guangzhou, the highest of them was achieved in September. It was also suggested that the solar radiation had no influence on the relative magnitude of the Qe,c, We and Wcom between HFO-1234ze(Z) and HFC-245fa systems. The Qe,c, We and Wcom of the system with HFO-1234ze(Z) were higher than those of HFC-245fa by 0.8%, 4.44%, and 3.55%, respectively.

Achieving a broad-spectrum photovoltaic system by hybridizing a two-stage thermoelectric generator

A novel solar hybrid system (SHS) that couples a two-stage thermoelectric generator (TTEG) to a dye-sensitized solar cell (DSSC) is put forward to broadbandly capture the inlet sunlight, in which the TTEG considers Thomson effect as well as Peltier effect and Seebeck effect. The mathematical relationship between the TTEG dimensionless operating electric current and the DSSC operating electric current is determined. Theoretical calculation indicates the maximum power output density (MPOD) and maximum energy efficiency (MEE) of DSSC are, respectively, 77.82 W m−2 and 4.94%, and the MPOD and MEE of SHS are, respectively, improved by 4.33% and 64.25% in comparison with the single DSSC. Moreover, the MPOD and MEE of SHS with Thomson effect are 1.49% and 0.05% smaller than that without Thomson effect, respectively. Exhaustive parametric studies are conducted to examine the dependence of SHS performance on comprehensive designing parameters and operating conditions, including temperature difference between operating temperature and environment temperature, Schottky barrier, thickness of porous nano-TiO2 semiconductor film, thermoelectric element (TEE) number ratio of top stage to bottom stage, total number of TEE, length and cross-sectional area of semiconductor legs. The obtained results are helpful for designing and optimizing such an actual SHS.

Hydration of cyclohexene to cyclohexanol in a hybrid reactive distillation with a side decanter

Nowadays, more than 1 Mt of cyclohexanol is produced each year by the direct hydration of cyclohexene according to the patented Asahi process proposed in 1990. The Asahi process involves a reactor and a separation system to recover the reactants back to the reactor and collect the pure product. The non-reacted water is recovered in a decanter and the non-reacted cyclohexene in a distillation column. Nowadays, many processes have been successfully intensified, combining several unit operations into a single unit providing savings in units, piping and often also in energy due to the synergies generated. Examples of these synergies are: the continuous removal of products push forward the reaction to total conversion overcoming the chemical equilibrium limitations; the catalyst placed in the rectifying section of the column becomes protected from heavy compounds that could poison or deactivate the catalyst; the enthalpy of reaction is directly used in the separation; the boiling point of the mixture avoids hot spots that could damage the catalyst, etc. Although its advantages, it is not widely used in the industry and further study on intensification providing further successful examples are required.The present study shows by rigorous simulation with Aspen Plus V9.0 that the Asahi process is a good candidate to be intensified in a single unit. The rigorous simulation results show that cyclohexanol is collected with a molar fraction purity of 0.9999 at the bottoms of a hybrid reactive distillation column with 11 equilibrium stages operated at total reflux, i.e. total conversion of reactants. The water is fed at the top to stage 1 and the cyclohexene on stage 3, both in equimolar flow rate. The catalyst is only placed in these three stages at the column top. A side stream from stage 6 is fed to a side decanter, where the aqueous phase is recycled to the column top (stage 1) and the organic phase to the next bottom stage, i.e. stage 7. As in the Asahi process, a great excess of water is present to push the reaction equilibrium forward. Hence, the molar ratio of water recycled vs feed to the system is of 125. The reboiler duty is 197 kJ/mol of cyclohexene, and the condenser duty is 564 kJ/mol cyclohexene due to the exothermic reaction. Therefore, a novel intensified process scheme for cyclohexene hydration is proposed.

Performance analysis of a two-stage gravitational water vortex turbine

In the present study the performance of two-stage gravitational water vortex turbine (GWVT) assembled in a conical basin with Savonius blade profile configuration has been investigated at different flow rate and vortex elevation. Two-stage GWVT with conical basin, not only increases the performance parameters with increase in flow parameters, but the lower stages also feed additional impact to the stage located above it because of forced vortex generation in the vicinity of top stage. Moreover, maximum hydraulic head drop near the orifice is the main contributor in the power generation of the bottom stage, by giving rise to strong tangential velocity. A stage starts power production as soon as the parabolic surface of the vortex approaches the corners of the blades even in the absence of a significant water-blade interaction. The developed analytical model qualitatively predicts the performance of the turbine minutely leading the experimental results quantitatively.

Competitive victimhood and reconciliation: the case of Turkish–Armenian relations

ABSTRACT This paper argues that conflicts tend to be intractable if collective victimhood has become a component of national identity, and when conflicting communities claim to be the ‘real’ or ‘only’ victims, and that their suffering justifies crimes past and present. Turkish and Armenian narratives of competitive victimhood are analysed drawing on public opinion polls from Turkey and Armenia, and personal interviews with Turks and Armenians. The study corroborates past theory and research that competitive victimhood prevents reconciliation, particularly if it has become an essential part of national identity. The paper also shows that Turkish–Armenian relations remain at the bottom stage of the reconciliation ladder. Yet, some of our empirical observations suggest that when grass-roots level interaction between Turks and Armenians is facilitated (which has been prevented not least because of the closed border), there is room for the abandonment of competitive victimhood at least on an interpersonal level, if not on a general societal or political level.

A Comparative study between MPC and PI controller to control vacuum distillation unit for producing LVGO, MVGO, and HVGO

This study describes the selection of controllers in the vacuum distillation unit (VDU) between a model predictive control (MPC) and a proportional-integral (PI) controller by comparing the integral square error (ISE) values. Design of VDU in this simulation is based on modified Metso Automation Inc. scheme. Controlled variables in this study are feed flow rate, feed temperature, top stage pressure, condenser level, bottom stage temperature, LVGO (light vacuum gas oil), MVGO (medium vacuum gas oil), and HVGO (heavy vacuum gas oil) flow rate. As a result, control performance improvements occurred as using MPC compared to PI controllers, when testing a set-point change, of feed flow rate control, feed temperature, top-stage pressure, bottom-stage temperature and flow rate of LVGO, MVGO, and HVGO, respectively, 36%, 6%, 92%, 53%, 90%, 96% and 88%. Only on condenser level control PI performs much better than the MPC. So PI controller is used for level condenser control. While for the test of disturbance rejection, by changing feed flow rate by 10%, there is improvement of control performance using MPC compared to PI controller on feed temperature control, top-stage pressure, bottom-stage temperature and flow rate LVGO, MVGO and HVGO 0.3%, 0.7%, 14%, 2.7%, 10.6% and 4.3%, respectively.