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Investigation of Performance Improvement of the Evaporation Process in Raw Sugar Manufacturing by Increasing Heat Transfer Surfaces
Abstract
A multiple-effect evaporator is used to evaporate water from sugar juice in a series of pressure vessels. Steam is used for evaporation in the first vessel, and vapor from all vessels except the last one is used for evaporation in subsequent vessels. In order for evaporator surfaces to be used efficiently, juice entering the evaporator should be at the saturation temperature. Therefore, incoming juice with a low temperature must be heated in a juice heater. The heating medium in the juice heater is vapor bled from the evaporator. It is apparent that the multiple-effect evaporator and the juice heater interact through mass and energy balances. Previous investigations have focused on only the multiple-effect evaporator, and paid little attention to the juice heater. This paper presents the model of the interaction between the multiple-effect evaporator and the juice heater. The model is used to investigate how variations of surfaces in the evaporator and the juice heater affect the two performance parameters of the system, which are the amount of sugar juice processed by the system and the ratio of the amount of water evaporated from sugar juice in the evaporator to the amount of high-pressure steam required by the evaporator.
... The evaporation unit in raw sugar manufacturing requires a large supply of thermal energy in order to remove a significant amount of water from the diluted sugar juice to produce sugar syrup (Chantasiriwan, 2017). The sugar juice is evaporated in the set of evaporator vessels known as multiple effects evaporators or evaporator station whereby steam is used in the first effect while evaporating vapors are used in the subsequent effects in the forward feed configuration (Khanam et al., 2008). ...
... The sugar juice is evaporated in the set of evaporator vessels known as multiple effects evaporators or evaporator station whereby steam is used in the first effect while evaporating vapors are used in the subsequent effects in the forward feed configuration (Khanam et al., 2008). Multiple-effect evaporator (MEE)consists of a number of pressure vessels operating at decreasing pressures (Chantasiriwan, 2017;Sorour, 2015;Khanam and Mohanty, 2010). Chantasiriwan (2017) suggested to improve the process performance have mostly focused on the multiple-effect evaporator by adding more effects or more heating surface areas and selecting the optimum distribution of evaporator surface. ...
... Multiple-effect evaporator (MEE)consists of a number of pressure vessels operating at decreasing pressures (Chantasiriwan, 2017;Sorour, 2015;Khanam and Mohanty, 2010). Chantasiriwan (2017) suggested to improve the process performance have mostly focused on the multiple-effect evaporator by adding more effects or more heating surface areas and selecting the optimum distribution of evaporator surface. In addition, the process performance can be enhanced by optimal operation scheduling of the evaporator and using the optimum tube dimensions for the evaporator. ...
Improving process performance is always important in any processing industry with the aim of reducing operation costs and improving the profit.Vapor bleeding may be used in processing industries using multiple-effect evaporatorsto reduces steam consumption and increases steam economyThe effect of vapor bleeding on separation performance using multiple-effect sugarcane juice evaporator was analyzed. The effect of increasing percent of vapor bled and determination of the most effective bleeding configuration in terms of energy efficiency and operating costs. The performance factors assessed were: steam requirement, total heat transfer area (At), steam economy, total utilized heat (Qt), mass flow rate of bottoms (Bi), percent solids in the bottoms (XBi), and mass flow rate of vapors. To carry out this work, a five-effect evaporator, forward feed computer model was developed based on mass and energy balance equations, calibrated by data from steam tables. Simulations incorporating different configurations of vapor bleeding were carried out. Bleeding from each of the first four effects, Ei , and from a combination of effects (E1&E3, E2&E4) were carried out. The E1&E3 configuration showed a highest decrease in steam consumption by 23.73% and improved steam economy by 31.28%. Also, vapor bleeding reduced At and XBi while increasingBi. This work suggests that to improve energy efficiency during separation of mixtures using evaporators, vapor bleeding should be practiced while maintaining a balance between vapors used to preheat the feed and that used for heating the subsequent effects.
... Steam Economy is the comparison of amount of evaporated water to amount of external steam used to evaporate the water (Chantasiriwan, 2017). ...
... To measure performance of MEE triple effect evaporator steam economy and steam on cane can be calculated. The definition of steam economy is the comparison of amount of evaporated water to amount of external steam used to evaporate the water (Chantasiriwan, 2017). Table 15 it can be seen that steam economy of triple effect evaporator is 1.8. ...
Pinch analysis for a sugar plant production capacity 4000 TCD has been carried out to reduce its energy consumptions. The plant has ten evaporators that can be configured to several multiple effect evaporators. It has been running with five-effect evaporator (quintuple) scheme. To maximize energy utilization within the plant, three multiple effect evaporator schemes were evaluated. They are triple effect evaporator, quadruple effect evaporator, and quintuple effect evaporator as the benchmark. The result shows that the quintuple effect evaporator yields the highest energy efficiency by about 10%. Options to achieve such target is to use low pressure steam only for the first effect and to use steam bleeding from the first effect to heat a tertiary juice heater. With this proposed scenario, sugar dryer, wash water RVF unit and wash water HGF unit no longer need external steam for its operation.
... Selain menghasilkan air kondensat, stasiun penguapan juga menghasilkan uap yang nantinya dipergunakan untuk media pemanas pada alat pemanas lain yang dikenal dengan sistem bleeding. Hasil simulasi dari Chantasiriwan (2017) [13] menyimpulkan bahwa kebutuhan uap akan minimum apabila dilakukan sistem bleeding. Jadi, sistem bleeding akan cukup menguntungkan bila diterapkan di pabrik gula, karena dapat meminimalkan penggunaan uap dari boiler. ...
The evaporation station has an important role in the sugar factory. This station aims to concentrate the sugar solution until it reaches its saturation point (± 60% Brix), so that the process of forming sugar crystals at the cooking station becomes easier. However, the evaporation station also contributes to the highest sucrose inversion compared other stations. Sugar solution (sucrose) is resistant to high temperatures, long periods of time, and low pH. Therefore, it is necessary to evaluate the evaporation station. To reduce the risk of sucrose inversion in the evaporation station, the sugar solution is heated in a pressure vessel (vacuum). Vacuum conditions can lower the boiling point of juice. Performance evaluation of evaporation station is measured by the total temperature drop (ΣΔT). The temperature drop is influenced by the distribution of pressure and temperature in evaporation, as well as the evaporation rate. The values of the parameters are compared with the literatures. The standard for the value of ΣΔT is 40, while the standard evaporation rate for the quadruple effect evaporation system with bleeding is 26 kg/(m2.hour). The results of the evaluation show that the highest ΣΔT value is 40.96 and the evaporation rate is 24.5 kg/(m2.hour), so it can be concluded that the operational condition of the evaporation station at PG Sindang Laut Cirebon is quite good. The evaporation system is also quite efficient. However, the evaporation rate is still categorized as inefficient
... Research Line 3-NCS production process optimization and greening: this line embraces process, equipment, and technological enhancement of sugar cane transformation on NCS. A total of 148 research documents (52,67%) comprise the highly developed research line: from milling process (Oktarini et al. 2019), passing through clarification (De Souza Sartori et al. 2017;Meerod et al. 2019), evaporation (Chantasiriwan 2017a(Chantasiriwan , 2017bGrewal and Kumar, 2021), concentration (Marie et al. 2020) and drying units process (Nishad et al. 2017(Nishad et al. , 2019. This trend promotes energy efficiency (Espitia et al. 2020;Gutiérrez-Mosquera et al. 2018;Srinvas et al. 2019; Venkata Sai and Reddy 2020), nutritional and sensorial Vera-Gutiérrez et al. 2019), and value added. ...
Food science innovation depends on consumers' needs and is currently seeking functional food with health effects. Non-centrifugal cane sugar (NCS) is known for its potential health effects, but there is a lack of holistic analysis on technological advancement and socio-economic and market trends for decision-making in the development of the technology. The aim of this article was to analyse the research trends, recent patents, and market trends and niches for NCS to structure an NCS technological roadmap. Scientometric, bibliometric methods, and global and local market information on NCS were used. Comprehensive analysis of the worldwide research trends and patents on NCS processing and of the growth of the main niche markets for Colombian NCS exports in the last five years was conducted. Finally, with the information obtained, an NCS technological roadmap was structured, which can be used as a tool for planning innovation processes and supporting the development of new research using market information and new norms forged by the COVID-19 pandemic for Colombian case. Furthermore, the methodological design could be used for other NCS producer countries.
Supplementary information:
The online version contains supplementary material available at 10.1007/s12355-022-01200-9.
... In order to produce raw sugar, 96 t/h of water must be removed from the juice. According to the recent analysis by Chantasiriwan (2017), the ratio of the amount of water content in juice to the amount of low-pressure steam required for the evaporation process depends on the heating surfaces in the process. For this study, this ratio is assumed to be 3. ...
The cogeneration system in sugar factory uses bagasse with high moisture content as the fuel for the boiler, which results in low boiler efficiency. The system also produces superheated steam, which is extracted from the turbine, and mixed with cooling water to produce saturated steam required by the evaporation system. The potential use superheated steam to reduce bagasse moisture content is ignored in the standard practice of the sugar factory. In this article, an investigation is made into the improvement of the cogeneration system by using superheated steam dryer to reduce the moisture content of bagasse. Mathematical models are developed for the typical system without superheated steam dryer and the improved system with superheated steam dryer. They are then used to compare the performances of both systems. It is found that, under the condition that the required steam flow rate for the evaporation process and the power output are the same, the improved system requires less bagasse consumption, and has larger energy utilization factor. In addition, water that would be lost with flue gases in the typical system is recovered in the improved system.
In the present work the sugar plant in Sragen, Central Java, Indonesia has ten evaporators that can be configured to five effect evaporators. The optimization ofenergy demand, finding optimum operating condition of LowPressure Steam (LPS), and choosing the best configuration of multiple effect evaporator (MEE) were performed by pinch analysis. In this paper, LPS at 0.4 kg/cm2.G – 1.1 kg/cm2.G were evaluated. The results show that the optimum operating condition of LPS was at 0.9 kg/cm2.G – 1.1 kg/cm2.G. This optimum operating condition enhances the energy saving by about 30% compared to that of existing plant (0.4 kg/cm2.G). The best performance value that can be achieved were Steam on Cane (SOC) by 43.50% and Steam Economy (SE) by 2.1
Current practice is to install clear juice heaters ahead of first effect evaporators to ensure that the juice entering the evaporator is above its boiling temperature, allowing flashing to occur on entry. The alternative, of allowing the juice heating to take place in the evaporator, is sometimes rejected on the basis that heating transfer performance of an evaporator is very poor when operating in the juice heating regime. To allow this alternative to be evaluated on a quantitative basis, available data on the relative heat transfer performance of juice heaters and Kestner evaporators have been collated, providing estimates of the difference in heating surface area required. By combining this information on heating surface area requirement with equipment costs, it is possible to make a rational assessment on whether it is advisable to dispense with clear juice heaters by installing extra heating surface area in the first effect evaporators.
In this work, a generalized steady-state mathematical model has been developed for simulation of the multiple effect evaporator (MEE) system, used in the Indian sugar industry. The developed model is capable of handling exhaust steam (saturated/superheated) inputs in more than one effect, vapor bleeding from desired effects, heat loss from each effect, and variations in boiling point rise as well as specific heat capacity with combination, heat transfer coefficient through external empirical correlations, and condensate flashing. The developed model has been solved by the globally convergent method. The results of present investigations have been validated against the data obtained from the Indian sugar industry with seven effects. The predicted exit liquor concentration, vapor body temperature, and amount of vapor bleed from each effect shows close agreement with the industry data within a maximum error band of ±2%. Further, a correlation has been developed for the prediction of overall heat transfer coefficient (OHTC) of each effect. The developed model can be further used to improve the steam economy of the MEE system by the incorporation of flash vapors from condensate stream.
The present study evaluates the performance of a triple-effect evaporator with forward feed (TEEFF) system by using exergy analysis based on actual operational data. The orange juice with a capacity of about 1.222 kg s−1 is concentrated from a dry matter (DM) content of 12 to 65% in this TEEFF, which is situated in an orange juice concentrate line installed in a factory, located in Denizli, Turkey. A Visual Basic 6.0 program was also developed to show how the exergetic performance characteristics of the system vary with the feed flow rates ranging from 1.222 to 1.667 kg s−1. The total exergy efficiency of the TEEEFF is found to be on average 0.85. The largest exergy destruction occurs in the first-effect of the TEEFF system with 48.2% of total, followed by the third and second effects with 32.04 and 19.76% of that. Evaporator performance is also rated on the basis of steam economy, which is obtained to be in the range of 2.05–2.14 under the operation conditions. It is expected that the analysis presented here should provide a designer with a better, quantitative grasp of the inefficiencies and their relative magnitudes in the design, simulation and operation of multiple-effect evaporators. Copyright © 2005 John Wiley & Sons, Ltd.
The cogeneration system in sugar factories consists of four main components: the juice extraction unit, the evaporation unit, the steam generation unit, and the turbo-generator. The juice extraction unit converts sugar cane into extracted juice, which is sent to the evaporation unit, and bagasse, which is sent to the steam generation unit. Combustion between bagasse and air in the steam generation unit produces high-pressure steam, which is used to drive the turbo-genenerator. Steam extracted from the turbo-generator is used to evaporate sugar juice in the evaporation unit. Desirable outputs from this cogeneration system are electricity produced from the turbo-generator and raw sugar produced from the evaporation unit. An important parameter that affects both outputs is the amount of imbibition water in the juice extraction unit. This paper attempts to find the optimum imbibition yielding the best combination of electricity and raw sugar that maximizes the profit.
Multiple-effect evaporator is used to increase the concentration of a solution in a series of pressure vessels. If the total surface area of the evaporator is fixed, the performance of the evaporator is affected by the distribution of surface area among vessels. Previous studies have been concerned with optimization of surface area distribution with the assumption that no fouling occurs. The present study considers a more realistic case when the last-effect vessel is subjected to fouling. The model of multiple-effect evaporator yields a system of nonlinear equations. Specified parameters are pressures and juice concentrations at inlet and outlet of the evaporator. The solution obtained from an iterative procedure is used to compute two objective functions, which are maximized at different optimum surface area distributions. Given a known rate of fouling, it is shown quantitatively how much the area of the last-effect vessel must be increased relative to the areas of the other vessels in order to achieve the maximum overall steam economy or the maximum amount of input to the evaporator.
In the present work a number of configurations and difficulties of MEE system such as condensate flashing, vapor bleeding, steam splitting, preheating of liquor using condensate, variable physical properties and boiling point rise are taken into consideration to analyze the evaporation system. For this purpose seven effect evaporator system of a typical Indian pulp and paper industry is considered. The model developed is a set of nonlinear algebraic equations that include total and solute mass balances, energy balances, heat transfer rate equations, and the composition and temperature dependence of thermodynamic properties such as vapor pressures and enthalpies. The model is solved using nonlinear equation solver.
Economic evaluation to optimize the number of flash tanks is carried out for seven effect evaporator system. The two different types of configurations of vapor bleeding are considered and compared. Considering optimum number of flash tanks and best configuration of vapor bleeding, a system is designed. Further, a modified system is found considering optimum number of flash tanks and preheating of liquor using condensate. This modified design enhances the steam economy by 23.77% and reduces the steam consumption by 36.76% in comparison to base case and thus, it is selected as optimum design. Finally, Pinch analysis of the MEE network has also been carried out and it is found that predicted results are compared well with base case.
The evaporation of sugar cane juice in a climbing/falling film evaporator was observed. Experiments were performed in a transient-batch, single-effect process with sugar juice concentrations varying from 15 to 40 Brix. In a traditional multiple-effect evaporator used in the cane sugar industry, this concentration ranges from that of the inlet of the first effect (15%) to that of the outlet of the third effect (40%). The variation in overall heat-transfer coefficient related to juice concentration was calculated, as well as surface-heat coefficients on the solution side and temperatures of the heating surfaces. A relative, more general, overall heat-transfer index was proposed.
Agro industry is a very important industrial sector worldwide, especially for countries like New Zealand and Chile. The main objective of this research was to propose a new economic evaluation procedure to optimize the design and operation of multiple effect evaporators and compare it with the traditional chemical engineering approach of total cost minimization. The proposed strategy incorporates a quality factor expressed as a function of lycopene concentration on the final product to find the optimal number of effects and operating conditions through the maximization of the net present value.The mathematical model was implemented using Microsoft Excel and considered mass and energy balances, specific relations for tomato concentration and a first order degradation kinetic for lycopene. The results indicate that when augmenting the capacity of the evaporation system of 5 effects from 50 to 75Ton/h, the lycopene retention increases from 95.25% to 96.27%. When evaluating the system through the logic of the total cost minimization, an optimum of 4 effects is found, but when evaluating the system using the maximization of the Net Present Value including lycopene as a quality parameter, the optimum is 3 effects.It appears of extreme relevance to consider quality as an intrinsic and integral part of the process design, as it will then be possible to identify several potential improvements in different food processes.
The main structural features of a multistage evaporator station are identified and their dependence on the requirements relating to the beet-sugar process is discussed. Developments in the scheme of multistage evaporation and preferred evaporator design over the recent decades are reviewed. Approaches making it possible to optimise the multistage evaporator station are mentioned and two examples of advanced stations implemented in beet-sugar factories by retrofitting outdated evaporation equipment are presented. It is stressed that the optimum retrofit results can be achieved by simultaneously reconstructing the evaporator station and the associated heat exchanger network.
In the present investigation a non-linear mathematical model is developed for the analysis of multiple effect evaporators (MEE) system. This model is capable of simulating process of evaporation and takes into account variations in -boiling point rise (BPR) due to variation in concentration and temperature of liquor, -overall heat transfer coefficient (OHTC) of effects and -physico-thermal property of the liquor. Using mass and energy balance around an effect, a cubic polynomial equation is developed to model an effect, which is solved using generalized cascade algorithm. For this purpose, a Septuple effect flat falling film evaporator (SEFFFE) system with backward feed flow sequence, being used for concentrating weak black liquor and operating in a near by paper mill, is selected as a typical MEE system. This system supports different operating strategies such as steam splitting and condensate-, feed- and product- flashing. The empirical correlations for BPR, OHTCs of flat falling film evaporators and heat loss have been developed using the plant data. Using these correlations, average errors of 3.4%, ± 10% and -33 to +29% have been observed for the predictions of BPR, OHTC and heat loss, respectively.
Mathematical modeling of the multiple effect evaporation (MEE) desalination process has been carried out to determine the effects of the important design and operating variables on the parameters controlling the cost of producing fresh water. The model assumes the practical case of constant heat transfer areas for both the evaporators and feed preheaters in all ef-fects. In addition, the model considered the impact of the vapor leak in the venting system, the variation in thermodynamic losses from one effect to another, the dependence of the physical properties of water on salinity and temperature, and the influence of noncondensable gases on the heat transfer coefficients in the evaporators and the feed preheaters. The modi-fied fixed-point iterative procedure is used to solve the large number of highly nonlinear equations describing the MEE desalting system. The algorithm consists of 10 calculation blocks and 6 logical blocks. The algorithm is implemented using L-A-S computer aided language. Results show that the heat transfer coefficients increase with the boiling temperature. Also, the heat transfer coefficient in the evaporator is always higher than that in the feed preheater at the same boiling temperature. The plant thermal performance ratio is nearly independent of the top brine temperature and strongly related to the number of effects. The specific heat transfer area increases by raising the number of effects and reducing the top brine temperature. The effect of the top brine temperature on the specific heat transfer area is more pronounced with a larger number of effects. The required specific heat transfer areas at a top brine temperature of 100 °C are 30.3% and 26% of that required at 60 °C when the number of effects are 6 and 12, respectively. The specific flow rate of cooling water is nearly constant at different values of top brine temperature and tapers off at a high rate as the number of effects is increased. Two correlations are developed to relate the heat transfer coefficients in the preheater and the evaporator to the boiling temperature. Design correlations are also developed to describe variations in the plant thermal performance, the specific heat transfer area, and the specific flow rate of cooling water in terms of the top brine temperature and the number of effects.
In the present work different energy reduction schemes (ERSs), used to reduce the consumption of steam for a multiple effect evaporator (MEE) system, are developed. These ERSs are condensate-, feed- and product-flashing and vapor bleeding. Further, a new scheme is proposed where condensate of vapor chest of an effect is used to preheat the liquor, which is entering into that effect using a counter current heat exchanger. This work also presents a comparative study between existing ERSs and selects the best ERS amongst these based on steam consumption as well as number of units involved. Further, in the present paper a simple graphical approach named "modified temperature path (MTP)" is developed for the analysis of different feed flow sequences of a MEE system to screen best possible feed flow sequence. To study the effect of different ERSs on steam consumption and MTP analysis an example of septuple effect flat falling film evaporator (SEFFFE) system, employed for concentrating weak black liquor in an Indian Kraft Paper Mill, is considered. The results show that ERSs reduce the steam consumption up to 24.6%.
Sugar factory retrofit often includes improvements in the factory’s energy system comprising power plant, multiple-effect evaporator and process heating equipment. To reduce the energy consumption, the evaporator subsystem and the process heating subsystem should be retrofitted to make improved heat recovery possible. The retrofit design procedure includes two stages: targeting for various options of the evaporator structure and selecting the most promising one, and designing both subsystems for targets so determined. At the targeting stage, one is confronted with the problem of designing the evaporation process and simultaneously considering the energy consumption. This constitutes an extension of the established targeting approach that assumes process conditions to be fixed. The problem can be transformed by decomposing the energy system, that is, conceptually separating the evaporator (in which vapours and condensates are generated) from the process heating subsystem (in which these heat carriers can be regarded as utilities). The transformed problem is one of targeting under constraints and can be solved iteratively by combining pinch analysis algorithm with evaporator simulator. The second stage of the retrofit design procedure requires defining the details of process heating subsystem that includes a heat exchanger network. This problem is conveniently solved using the network pinch approach.
This paper describes a phenomenological, stationary and dynamic model of a multiple effect evaporator for simulation and control purposes. The model includes empirical knowledge about thermophysical properties that must be characterized into a thermodynamic equilibrium. The properties selected evolved from an economical optimisation because of their influence on the temperature and concentration variations parameters. The developed model consists of differential and algebraic equations that are validated using a parameter sensitivities method that uses data collected in the industrial plant. The simulation results show a qualitatively acceptable behaviour. The values of the estimated parameters are physically appropriate for the process. The study of parametric sensitivity and more generally of the model sensitivity, with respect to variables has been judicious for the parameter estimation as for the choice of suitable data for model validation. This study shows also that the most important parameters of the process are the global heat transfer coefficient and the latent heat of vaporization.
The handbook has included the description of cane sugar manufacture, mills, diffusers, boilers and other factory machinery, calculation methods of capacity for every piece of equipment, and process and manufacturing techniques. This new edition has been revised and information that is either obsolete or of little interest has been deleted or shortened. Additions have been made in chapters dealing with recently developed equipment and a completely new chapter covers automation and data processing. Numerous figures, graphs, drawings, photographs, tables and formulae are provided.