Multiple Effect Evaporator Research Articles

Modelling reverse osmosis process and multiple effect evaporator process of common effluent treatment plant using artificial neural network

This paper presents the study on modeling the performance of Textile and Tannery Common Effluent Treatment Plant (CETP) using Artificial Neural Networks (ANN). The process of Reverse Osmosis (RO) Process and Multiple Effect Evaporator (MEE) process of CETP is modelled using ANNs. Two ANN models were developed to predict the performance of CETP dealing with highly saline effluents. Model-I (RO Model) predicts TDS Rejection (%) by taking pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Chemical Oxygen Demand (COD) of RO feed as input parameters thus providing estimate of salt concentration. Model-II (MEE Model) predicts Steam Output needed by taking pH, TDS, Feed flow as input parameters. Levenberg-Marquardt backpropagation (trainlm) algorithm was used as training function for creation of both of ANN models and Hyperbolic Tangent Sigmoid (tansig) was used as transfer function. Separate model validation has been performed to test the predictability of the model and at last prediction accuracy were analysed to show its efficiency in prediction.

Comparison between Calculated, Simulated and Actual Plant Data of Multiple Effect Evaporators to Concentrate Sugarcane Juice

Multiple effect evaporators systems operating at steady state can be described by a series of nonlinear algebraic equations that include total and solute mass balances, energy balances, heat transfer rate equations, and the composition and temperature dependence of related thermodynamic properties such as vapor pressures and enthalpies. The main objective is to compare between the manual calculations, simulation and real data collected from Asalaya plant for validation the best design of multiple effect evaporators system in forward feed used in Asalaya Sugar Factory. In this design a short tube vertical evaporator, Calandria type has been used. The models include overall equations of materials balance, equations of energy balance and equations of heat transfer rate for measurement area for all the effects. These equations were solved using manual calculations methods and MATLAB coded program. The results of the present investigations have been compared with the data obtained from the Asalaya Sugar Factory with five evaporators. The results showed that the concentration of sugar cane juice at the final stage is equal to 60 Brix for the manual calculations, simulation and actual plant data with zero error. The temperature of solution in the pre- effect evaporator was found to be about (114.94, 114.94, 115)ºC, with a relative error equal to 0.05% and the steam temperature in the pre effect was found about (120)ºC for the manual calculations, simulation and actual plant data, with zero error. The area and number of tubes in the (pre, second, third and fourth) effect, are in a good agreement, with the standard value (Er=3.26%). The above results show great similarity with the real behavior of evaporator unit. This can be used as a reliable tool\for the simulation of different operating conditions.

Failure analysis on premature perforation of multiple effect evaporators in vacuum salt making system

Multiple effect evaporators (MEEs) are extensively utilized across diverse industries, such as pulp and paper, sugar, and desalination, for the purpose of concentration and purification. Nevertheless, MEEs often bring forth the issue of corrosion because of severe service conditions, thereby leading to equipment damage and decrease in efficiency. This study scrutinizes the premature perforation and corrosion of some multiple effect evaporators encountered soon after their commencement in a salt processing plant. The failed MEEs, designed to serve for 15 years, underwent severe corrosion and the emergence of multiple leakage points during a trial run of 40 days, with only 18 days of actual operation. To unearth the reasons for this failure, various macroscopic and microscopic analyses were carried out. The studies demonstrated that welding defects not found in time during the fabrication of evaporators reduced the corrosion resistance of the composite plate. Additionally, improper welding during the maintenance made the repair ineffective. Once the stainless-steel cladding layer was damaged, the carbon steel backing layer corroded and perforated rapidly under galvanic corrosion. Based on these findings, effective countermeasures were suggested to evade any future failures of the same kind. The outcomes of this analysis are likely to aid in enhancing the operational safety and reliability of multiple effect evaporators in vacuum salt-making systems.

Techno-economic and environmental analysis of high temperature heat pumps integration into industrial processes: the ammonia plant and pulp mill cases

Heat pumps will play an important role in improving the performance of the industrial processes aiming to decarbonize their heating requirements. Yet, defining the best operating conditions of those devices may be a challenging task, as they are embedded in larger energy conversion systems and in direct competition with fired and electric heaters and other waste heat recovery systems. The costs of the energy inputs also influence the selection of either a heat pump or a gas boiler, which affects the overall efficiency and the incremental cost of the final solution. Thus, a systematic analysis must be applied in order to determine the best option to supply the heating requirement, without considerably impacting the operational feasibility of the overall plant. In this work, the base-case performance of two industrial applications with intensive heating demand, namely, the solvent regeneration process of a carbon capture unit and the black liquor concentration process of a kraft pulp mill, are compared to that of the scenarios in which a high temperature heat pump or a mechanical vapor recompression unit are integrated, aiming to reduce the energy consumption and the environmental impact. The benefits of the integration of a heat pump or a mechanical vapor recompression unit over a conventional reboiler and a multiple effect evaporation system are discussed in the light of thermodynamic, economic and environmental indicators. As a result, the alternative approaches remain competitive vis-à-vis the conventional solutions in terms of energy consumption and operating costs. In addition, the emissions associated to the heating applications could be reduced by 45% if a high temperature heat pump is integrated. The optimized solution using a heat pump has an overall exergy efficiency 9% higher compared to the typical configuration of the ammonia plant. In pulp mills, the integration of mechanical vapor recompression systems slightly affects the performance compared to the conventional scenario with a multiple effect evaporation system.

Optimization of Heat Transfer Area and Steam Requirement in Multiple Effects Evaporator for Concentration of Juice in Sugar Factory

<strong>ABSTRACT.</strong> In maintaining the existence of sugar factories that exist and are still actively operating in Indonesia, efforts should be made to carry out intensification and extensification. In terms of the intensification of the process, it is necessary to periodically evaluate the performance of process tools, especially those that require utilities so that the process is effective and efficient. The process of making sugar passes through six stages, namely: milling, purification, evaporation (evaporation), cooking, screening, and packaging processes or the final stage. The evaporation process is a crucial process that determines the success of the entire process because the juice is concentrated from 11% to 64%. The evaporator is designed to use a multiple effect evaporator to increase the value of steam economy. The research objective is to optimize the number of effects that require a minimum total cost. To achieve this goal, it is necessary to survey the sugar factory to obtain the necessary valid data. Furthermore, a mathematical model is compiled based on the principle of mass and heat balance and then a software program is made so that the optimization solution can be done accurately. The conclusions that can be drawn are as follows: for a mass flow rate of 125,000 kg/hour with a concentration of 11% juice and a feed temperature of 100<sup>o</sup>C, the optimum conditions are obtained with a minimum annual production cost of IDR. 22,090,361,779.00 which is owned by the evaporator with 4 effects, total evaporator area = 2,443.81 m<sup>2</sup>, steam economy = 3.98 and steam demand = 26,028.2 kg/hour. The number of evaporator effects of 4 is common in Indonesia.

Multiple-Effect Evaporators in the Food Industry: Fundamentals, Design, Simulation, Control, and Applications

Multiple-Effect Evaporators in the Food Industry: Fundamentals, Design, Simulation, Control, and Applications

Comprehensive treatment of aroma chemicals industrial effluent with substantial COD content by a novel PVP/polyamide composite hydrophilized RO membrane

A hydrophilized polyvinyl pyrrolidone/polyamide composite high rejection reverse osmosis (HPA-HR RO) membrane was used for the treatment of aroma chemicals containing effluent coming as multiple effect evaporators (MEE) condensate at UK Aromatics Pvt. Ltd., Boisar, Maharashtra. The unique membrane has an active composite layer of polyamide prepared by interfacial polymerization of high diamine (3%) and acid chloride (0.2%) monomer concentrations, which is further coated with polyvinyl pyrrolidone (PVP) to enhance hydrophilicity and chemical inertness. The plant provides removal of total dissolved solids (TDS) from 2500 to 3500 ppm in the feed to a value of 50–100 ppm in the permeate water indicating a rejection of more than 95% of the dissolved solids, with a high water recovery of 80% in permeate. Similarly, complete rejection of color was observed from dark brown to colorless (transparent), whereas the COD content was brought down from 3000 to 5000 mg/L in the MEE condensate to around 1000 mg/L indicating removal of 60 % to 80% depending upon the pressure applied to overcome the high osmotic pressure of the effluent. Physicochemical interactions between the PVP and polyamide skin layers of the composite membrane make the separating barrier durable and highly hydrophilic. Water would have greater sorption due to high affinity with the membrane and higher diffusion coefficient from its smaller size, while the less polar esters that constitute most of the COD would have low interaction and their larger molecular sizes make them less diffusive. The recovered permeate water has been reused in various internal industrial applications like cooling towers, cleaning, etc. at UK Aromatics.

Operational optimal control of industrial evaporation process using noisy and multimode data

Operational optimal control (OOC) aims to maintain the process indexes of an industrial process within the desired range by deciding the control set points. However, the optimization is made difficulty because the key process index cannot be measured online and accurate model for optimization is not available. This work deals with these issues in an industrial multiple-effect evaporation process, with the goal of controlling the product liquor density. The proposed operational optimization framework dynamically finds the optimal control set points through the collaboration of an initial optimizer, a data-driven key process index predictor and a set point compensator. The process index predictor is developed based on the hierarchical Gaussian mixture model, which approximates the distribution of noisy and multimode process data. Then, the same model is used for finding the optimal compensation set points online, where an efficient sampling based stochastic search algorithm is proposed. The proposed method is tested using simulation and in a real industrial evaporation process showing superior performance.

Renewable integration and energy reduction in multiple stage evaporator

• Development of steady state energy model for a hybrid MSE. • Formulating the constrained optimization problem to maximize energy efficiency. • Implementation of a metaheuristic approach named Flow Direction Algorithm. • Incorporation of FTs and LFR to reuse waste heat and meet required thermal demand. Multiple Effect Evaporator (MEE) is an imperative part of the paper industry. It is used to process the waste byproduct named Black Liquor to enhance its solid concentration that may be further utilized to produce biomass-based energy. This process accounts very high energy consumption which leads to the energy intensiveness of this unit. A substantial amount of energy-saving may be accumulated by integrating various Energy Reduction Schemes (ERSs) with the MEE. Steam splitting, feed splitting, feed liquor preheating, thermo-vapor compressor, etc. are the well-known ERSs that may be incorporated with the MEE to reduce energy utilization. Hence, this study investigates the hybrid ERSs incorporated with MEE to observe their energy efficiency in an optimal manner. The prime focus of this investigation is to achieve enhanced energy efficiency in teams of maximum steam efficiency which is computed by formulating the nonlinear mathematical models of the MEE. To achieve the maximized energy efficiency, an optimization function has been developed under a constraint environment and solved by using metaheuristic-based approach named Flow Direction Algorithm. Another ERSs named flash tanks can also be integrated with this system to encourage waste heat re-utilization and ensures an increase in energy efficiency with constant steam consumption. This work also deals with the incorporation of the Linear Fresnel Reflector with ERSs integrated MEE which is capable of reducing the conventional energy load. The overall integrated MEE model achieves an energy-efficient and renewably operated MEE unit that may enhance the self-sustainability of the industry.

Optimizing cogeneration and desalination plants by incorporating solar energy

Typically, desalination facilities are integrated with thermal power plants that include steam turbines, simple-cycle gas turbines, and combined-cycle gas turbines. Desalination is accomplished using the following technologies: thermal (multistage flash desalination and multiple-effect evaporation) and membrane (reverse osmosis). Because of the significant economic and environmental impacts of power generation and desalination, there is a critical need to optimize costs and to reduce emissions, especially the carbon footprint. Solar energy is a promising approach to reducing CO2 emissions. The goal of this study is to minimize the total annual cost for desalination facilities powered by thermal power plants, photovoltaic arrays, and battery storage. A single-objective nonlinear optimization approach addresses economic and environmental factors. A multi-period strategy accounts for seasonal variations in energy consumption, water consumption, solar energy supply, fuel prices, and fuel availability. The model is applied to a case study on the water-energy nexus for desalination-power plants in Kuwait. The optimization scheme selects from among various types of fossil fuels: natural gas, gas oil, heavy fuel oil, and crude oil. The study includes optimization with implementation of a carbon tax and constraints on CO2 emission. Over a tax range of $20–120/t CO2, the optimal solutions have a constant capacity of the photovoltaic array. Above $120/t CO2, a sharp increase occurred in the array capacity, and all power was generated by the array.

Application of a predictive Q-learning algorithm on the multiple-effect evaporator in a sugarcane ethanol biorefinery

With the recent development of machine learning, reinforcement learning is an interesting alternative to PID controllers. In this context, a discrete predictive Q-learning approach is applied in the control of a sugarcane biorefinery multiple-effect evaporation system. The algorithm is built using Scilab and learns to control the multiple-effect evaporator outlet concentration by manipulating its feed steam flow rate. Based on multiple episodes, the state-actions that consist of discrete changes in steam flow rate are chosen with a greedy algorithm. In order to increase the training efficiency and overcome the large dead time of the system, a neural network is applied to predict the outlet concentration of each control action after reaching the steady-state. The control policy was built and tested through simulations on a phenomenological model. The controller performance was evaluated in set-point tracking and disturbance rejection tests and compared with PID responses. The research showed that the Q-learning controller exhibited better performance than the PID controller.

Optimization of a Multiple-Effect Evaporator Process by Simulation

Simulation is used to solve complex problems in the pulp and paper industry through process modeling based on the predicted values obtained to understand the characteristics and behaviors of the actual process of interest. The study aim was to evaluate a multiple-effect evaporator (MEE) model built using WinGEMS and determine the overall efficiency of the MEE based on different case studies of black liquor and steam feed arrangements. Efficiency was much better with the backward feed arrangement than with other models in terms of steam economy predicted. For more accurate simulation optimization in the MEE process, however, an actual dataset should be used to evaluate the mode efficiency.

Controller design for optimal operation of Multiple Effect Evaporator of paper mills

The Kraft recovery process in the paper mills is highly complex and nonlinear. The evaporation of black liquor using Multiple Effect Evaporators (MEE) in the recovery unit of the Kraft process is an energy-consuming procedure. The challenge lies in designing a proficient control strategy to conserve energy and guarantee good product quality. In this article, the 2-DOF-PI controller is designed to enable efficient control of MEE and eliminate process uncertainties. The Heptads’ Effect Falling Film Evaporator in the backward feed flow configuration is used as a working platform. The steady-state and transient behavior of MEE is modeled and analyzed to assist in controller design. The steady-state process parameters, that guarantee optimum energy efficiency, are estimated using Moth–Flame Optimization (MFO). MFO is also employed to estimate the optimal 2-DOF-PI controller parameters to attain improved product quality and energy-efficient performance of MEE. The competence of MFO towards controller tuning is shown by a fair comparison with some well-known optimization techniques. The quantitative investigation of the statistical results demonstrates that MFO outperforms the other algorithms. To validate the proficiency of the designed control scheme, its performance is compared with basic PI/PID control strategy for set-point tracking, noise suppression, and process uncertainties. The simulation results indicate that the designed MFO-tuned 2-DOF-PI controller offers efficient control action and, therefore, proves to be an appropriate control algorithm to ensure sustainable production.

Dynamic simulation of multiple-effect evaporation

The main purpose of this work is to simulate multiple-effect evaporation and its variation as a result of the interconnection between batch and continuous unit operations. Therefore, the challenges posed by the hybrid continuous-discrete character of the model are addressed. The computer code is based on detailed fundamental material and energy balance equations, physical and thermodynamic properties, and well-proven correlations for the heat transfer coefficients. A sugarcane industry was used to demonstrate the effectiveness of the model; in this industry, there is an interconnection between a batch and a continuous process. The steam consumed in the batch process changes in each batch step. The results showed that changing the steam flow rate changes the pressure of the steam produced in a multiple-effect evaporation. Additionally, when a bypass valve and a relief valve are used to maintain constant steam pressure, it increases the overall steam consumption.

Application of fuzzy control in the evaporation stage of a first- and second-generation sugarcane ethanol biorefinery

Sugarcane bagasse is a cheap feedstock for one of the most significant biofuel technologies currently being developed: second-generation ethanol (E2G). Most studies regarding E2G production investigate ways to improve the efficiency of this technology. However, studies about its control are still very sparse. In this work, we tried to partially fulfill this gap, addressing the control of a multiple-effect evaporation system of a sugarcane biorefinery. A feedforward fuzzy controller was proposed with membership functions based on a dynamic phenomenological model developed in Environment for Modeling, Simulation, and Optimization (EMSO). This software was also used to carry out simulations to evaluate the disturbance rejection performance. Inference tools based on neural networks and proportional–integral (PI) controllers were also proposed as support to the Fuzzy control system. The tests showed that the Fuzzy scheme outperformed traditional proportional–integral–-derivative (PID) controllers, settling on average 66% faster with a 72% reduction of integral time absolute error (ITAE).

Design and Economic Assessment of Alternative Evaporation Processes for Poly-Lactic Acid Production.

In this work, alternative evaporation processes for PLA production were designed with economic assessment. The suggested processes are the multiple-effect evaporation (MEE) process and thermal vapor recompression (TVR)-assisted evaporation process. First, the MEE process can efficiently reuse waste heat by additional column installation, thereby reducing the steam energy consumption. The proposed MEE process involves five columns, and after the evaporation in each column, the waste heat of the emitted vapor is reused to heat steam in the reboiler of the next column. Second, the suggested TVR-assisted evaporation process utilizes an additional steam ejector and recovers waste heat from the emitted vapor by increasing the pressure using high-pressure driving steam at the steam ejector. Each alternative process was modeled to predict the steam energy consumption, and to determine the cost-optimal process; the total annualized cost (TAC) of each alternative process was calculated as evaluation criteria. In the simulation results, the alternative processes using MEE and TVR reduced the steam consumption by 71.36% and 89.97%, respectively, compared to the conventional process. As a result of economic assessment, the cost-optimal process is the alternative process using TVR and the TAC can be decreased by approximately 90%.

The Effect of Operating Condition on Low Pressure Steam (LPS) in Sugar Factory by Pinch Analysis

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

Sustainable cleaner production technologies and treatment of segregated effluent streams with recovery of quality salt, chromium & water

Conventional process and treatment system adopted by Indian and Global Tanneries consist of Segregation of Spent Chrome Stream and discharge of supernatant for combined treatment along with effluent from all sectional operations starting from soaking to finishing, Conventional physiochemical and biological treatment for reduction of Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), etc., Ultra-filtration and Reverse Osmosis (RO) system for recovery of water and Multiple Effect Evaporator (MEE) for the evaporation of RO reject stream and generation of mixed salt in case of Zero Liquid Discharge (ZLD) system and Storage of mixed salt recovered from the MEE system for which no viable disposal system is found. Establishment of treatment system for the mixed stream results in poor performance of biological treatment units, increases the Operation & Maintenance (O&M) cost and accumulation of recovered mixed salt in case of ZLD system. It is estimated that, more than 8-10 tones of mixed salt is generated during the treatment of 1.0 MLD effluent under ZLD system. To address this serious environmental problem, an innovative approach of segregation of saline streams such as soak liquor and chrome liquor are planned to be collected separately with the feasibility of recovering reusable quality salt and chromium in the form cake for regeneration and use in the form of Basic Chromium Sulphate (BCS) by the tanneries. This innovative treatment concept has been developed and is being implemented in many Common Effluent Treatment Plants (CETPs) in India. This will become the first of its kind in Global Leather World. This developmental scheme is in accordance with the guidelines and recommendations of UNIDO in terms of sustainability of ZLD system for leather sector. The technological developments on cleaner productions, centralized chrome recovery reuse system, segregation of saline soak water for separate treatment with recovery of water and quality salt are dealt in this technical paper.

Synergistic optimization of electrocoagulation process parameters using response surface methodology for treatment of hazardous waste landfill leachate

Leachate treatment is an essential and integral part of solid waste management system, and its efficient treatment becomes more crucial when the leachate is produced from industrial or hazardous waste landfills (HWLs), as it is multi-fold more toxic than the leachate produced from municipal solid waste landfills (MSWLs). Electrocoagulation has appeared to be a promising technology for treating complex wastewater including MSWL leachate, but specific treatability studies dedicated to HWL leachate are rarely available, and thus pose a demand for fundamental and advance research in this area to bridge the existing gap. The current study delves into systematic design of experiments to check the treatability of HWL leachate through electrocoagulation, considering reduction (maximum) in chemical oxygen demand (COD) as a response variable. Response Surface Methodology (RSM) was used for design of experiments and process optimization and three-dimensional surface response was also created to understand the relationship among process parameters and response variables. After extensive experimental trials and data analysis, it was observed that electrocoagulation can be used as a potential treatment technology for leachate with Galvanized Iron (GI) as preferable electrode material and it resulted up to 90% reduction in COD under optimized condition. Significant reduction in other parameters was also observed with a removal efficiency of 58.1%, 63.6%, 42.4%, 52.5%, 54.7% and 84% for cadmium, zinc, phenolic compounds, lead, TOC, and colour, respectively. The results showed that Electrocoagulation can be used as a replacement of currently practised energy extensive treatment technologies like multiple effect evaporators, which are used by landfill operators for managing their HWL leachate. The methodology and results from this research may be utilized by the researchers and operators of HWL landfills to decide the treatment trail for HWL leachate.

Optimizing the energy efficiency of multiple effect evaporator house using metaheuristic approaches

Optimizing the energy efficiency of multiple effect evaporator house using metaheuristic approaches