Large-scale and complex process systems are essentially interconnected networks. The automated operation of such process networks requires the solution of control and optimization problems in a distributed manner. In this approach, the network is decomposed into several subsystems, each of which is under the supervision of a corresponding computing agent (controller, optimizer). The agents coordinate their control and optimization decisions based on information communication among them. In recent years, algorithms and methods for distributed control and optimization are undergoing rapid development. In this paper, we provide a comprehensive, up-to-date review with perspectives and discussions on possible future directions.

Over the last three decades, flexibility and controllability considerations for heat exchanger networks (HENs) have received great attention, respectively. However, they should be simultaneously incorporated in HEN synthesis to allow the economic performance to be achievable in a practical operating environment. This paper proposes a method for simultaneous synthesis of flexible and controllable HEN by considering their coupling. The key idea is to add the bypasses with optimized initial fractions and positions to explore such coupling, and consequently enabling HENs to be operated successfully over a range of disturbance variations. These are implemented by identifying and quantifying disturbance propagations, and then examining the sensitivity of bypasses to the entire HEN. In this way, the superstructurebased mixed integer non-linear programming (MINLP) with objective function of minimizing the total annual cost is formulated. A case study is used to demonstrate the application of the proposed method. Quantitative measures and dynamic simulation show the ability to provide the satisfactory flexibility and controllability of the obtained HEN.

Dealing with uncertainty is one of practical issues in design and operation of heat exchanger networks (HENs), arising the problem of flexible HEN synthesis. This paper addresses the state-of-the-art methods for flexible HEN synthesis based on sensitivity analysis, resilience analysis, flexibility analysis and multiperiod synthesis techniques as well. Each of these methods is summarized by presenting their general procedures and recent developments on modeling, solving strategies and applications. Some current topics related to flexible process synthesis have been briefly presented to provide several future research possibilities.

To realize the industrialization of the novel single-column air separation process proposed in previous work, steady-state simulation for four different configurations of the single-column process with ternary (nitrogen, oxygen and argon) is developed. Then, exergy analysis of the single-column processes is also carried out and compared with the conventional double-column air separation process at the same capacity. Furthermore, based on the steady-state simulation of single-column processes, the different heat exchanger networks (HENs) for the main heat exchanger and subcooler in each process are designed. To obtain better performance for this novel process, optimization of process configuration and operation is investigated. The optimal condition and configuration for this process is consisted as:feedstock is divided into two streams and the reflux nitrogen is compressed at the approximate temperature of 301 K. In addition, HEN is optimized to minimize the utilities. HENs without utilities are obtained for the four different configurations of single-column process. Furthermore, capital costs of the HEN for different cases are estimated and compared.

Extractive distillation is an effective method for separating azeotropic or close boiling point mixtures by adding a third component. Various technologies for performing the extractive distillation process have been explored to protect the environment and save resources. This paper focuses on the improvement of these advanced technologies in recent years. Extractive distillation is retrieved and analyzed from the view of phase equilibrium, selection of solvent in extractive distillation, process design, energy conservation, and dynamic control. The quantitative structure-property relationship used in extractive distillation is discussed, and the future development of extractive distillation is proposed to determine how the solvent affects the relative volatility of the separated mixture. In the steady state design, the relationship between the curvature of the residue curve and parameters of the optimal steady state is also highlighted as another field worthy of further study to simplify the distillation process.

The rapid increase in energy demand, the extensive use of fossil fuels and the urgent need to reduce the carbon dioxide emissions have raised concerns in the transportation sector. Alternate renewable and sustainable sources have become the ultimate solution to overcome the expected depletion of fossil fuels. The conversion of lignocellulosic biomass to liquid (BtL) transportation fuels seems to be a promising path and presents advantages over first generation biofuels and fossil fuels. Therefore, development of BtL systems is critical to increase the potential of this resource in a sustainable and economic way. Conversion of lignocellulosic BtL transportation fuels, such as, gasoline, diesel and jet fuel can be accomplished through various thermochemical processes and processing routes. The major steps for the production of BtL fuels involve feedstock selection, physical pretreatment, production of bio-oil, upgrading of bio-oil to transportation fuels and recovery of value-added products. The present work is aiming to give a comprehensive review of the current process technologies following these major steps and the current scenarios of biomass to liquid facilities for the production of biofuels.

It is of importance to convert glycerol, the primary by-product from biodiesel manufacturing, to various valuable C₃ chemicals, such as acrolein via dehydration, lactic acid, 1,3-dihydroxyacetone via oxidation, and 1,3-propanediol, allyl alcohol via hydrogenolysis. As compared to petroleum-based resources, C₃ chemicals from glycerol provide a benign, sustainable and atomically economic feature. Extensive heterogeneous catalysts have been designed, prepared and tested for these transformations. In recent five years, great progress, including high yields to target products over appropriate catalysts, insight into reaction mechanism and network, has been achieved. The present review systematically covers recent research progress on sustainable C₃ chemical production from catalytic glycerol transformations. We hope that it will benefit future research on transformations of glycerol as well as other polyols.

Papermaking industry is a high-energy-consuming industry with long supply chain. The growth of paper product demand further intensifies the need of energy consumption. Energy saving through the full supply chain has become a focal point for long-term sustainable development of the papermaking industry. This paper reviews the advances in life cycle analysis for the papermaking industry in recent years. All the stages from the full supply chain are involved to give a panoramic overview of the papermaking industry. The object of this paper is to provide scientific basis to industry and decision-makers with profound understanding of the energy consumption and energy saving potential in a life cycle perspective.

Novel technologies in consideration of industrial sustainability (IS) are in urgent need to satisfy the increasing demands from the society. IS realizes the production of materials while maintaining environmental and resource sustainability. The chemical materials used in CO₂ capture and storage (CCS) technologies play a significant role in the disposal of greenhouse gas emissions coming from large stationary fossil-fired power plants, which breaks the principle of IS and brings severe environmental problems. This study aims at providing a detailed review of first-principles modeling (density functional theory, DFT) of materials in CO₂ capture technologies. DFT analysis provides insight into the atomic properties of the studied systems and builds an efficient guidance of the future design of the materials used in CO₂ capture technologies. Major materials including oxygen carriers, metal organic frameworks, membranes, zeolites, ionic liquids and some other promising candidates are considered. The computational studies bring the outcomes of the adsorption behaviors, structural characteristics and accurate force fields of the studied materials in short turn-around times at low cost. This review can stimulate the design of novel materials with specific target of CO₂ capture and promote the industrial sustainability of fossil fuel combustion technologies.

Despite the current threat from climate change, plastic collecting in the world's oceans, and the steady loss of biodiversity, the world continually fails to take action with regard to our rapidly changing ecosystem. Unfortunately, waiting on governments to act is no longer a viable option. Rapid change is needed and the pace of diplomacy is simply too slow. Democratic governments are reactionary and taking action to solve future problems is not a priority, even as the threat of potential ecological catastrophe draws ever closer. Change is in the hands of individuals, and it is our decisions and behaviors that will influence the future of our planet and our ability to inhabit it. Therefore, building momentum for sustainable behavior must begin with individuals. The neoliberal approach to environmental protection posits that individuals are motivated by rational self-interest, and that economic incentives are necessary to achieve environmental goals. However, recent research suggests that monetary gain alone actually negatively impacts behavior, and often neglects the rural poor. As a result, models for projects designed to benefit the environment need more than just a monetary incentive, they must incorporate all three pillars of sustainability:environment, economy and society. One approach for building momentum for sustainable behavior with regard to municipal solid waste management, particularly in the developing world, is by implementing Locally Managed Decentralized Circular Economy (LMDCE) principles. This contribution will describe the role behavioral economics plays in the choices made by producers and consumers. The results of a case study on applying LMDCE principles in Uganda to manage waste plastic accumulation by conversion to fuel oil will be presented.

Due to the rapid urbanization and industrialization, and excessive consumption of fossil fuel, haze weather characterized by PM_2.5 has become a severe pollution problem in major Chinese cities recently, which has harmful effect on the air quality, visibility, clime system and human health. To indicate suitable directions for the prevention and control of haze pollution, the pollutant source apportionment and formation mechanism of urban haze should be figured out firstly. In this work, we briefly review the frequently-used methods for PM_2.5 source apportionment and formation mechanism analysis of urban haze based on normal perspective in recent years. Furthermore, based on the new perspective of systematic methodology, the utilization of fault tree approach for the causation mechanism analysis of urban haze is significantly introduced and discussed. Finally, the recent progress on controlling strategies of urban haze in China is also synoptically introduced and discussed. It is expected that more effective tool/method can be found, developed and employed for the causation mechanism analysis and risk management of urban haze in China.

Sustainable production of clean water is a global challenge. While we firmly believe that membrane technologies are one of the most promising solutions to tackle the global water challenges, one must reduce their energy consumption and fouling propensity for broad sustainable applications. In addition, different membranes face various challenges in their specific applications during long-term operations. In this short review, we will summarize the recent progresses in emerging membrane technologies and system integration to advance and sustain water reuse and desalination with discussion on their challenges and perspectives.

The flow behavior of gravity-driven falling film of non-conductive high viscosity polymer fluids on an industrial-scale vertical wavy wall was investigated in terms of film thickness and residence time distribution by numerical simulation and experiment. Falling film flow of high viscosity fluids was found to be steady on a vertical wavy wall in the presence of the large film thickness. The comparison between numerical simulation and experiment for the film thickness both in crest and trough of wavy wall showed good agreement. The simulation results of average residence time of falling film flow with different viscous fluids were also consistent with the experimental results. This work provides the initial insights of how to evaluate and optimize the falling film flow system of polymer fluid.

Pervaporation is an important membrane separation method of chemical engineering. In this work, silver-nanoparticles-poly (vinyl alcohol) nanocomposite membranes (AgNPs-PVA) are produced for the sake of improving its potentials for pervaporation of ethanol-water mixture so that the usual opposite trend between membrane selectivity and permeation can be reduced. The nanocomposite membranes are fabricated from an aqueous solution of poly (vinyl alcohol) with silver nanoparticles via the in-situ generation technique in the absence of any reducing agent. Successful generation of the nano size silver is measured by the UV-vis spectrum showing a single peak at 419 nm due to the plasmonic effect of silver nanoparticles. Our nanocomposite AgNPs-PVA membranes are characterized using scanning electron microscope (SEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction and thermogravimetric analysis (TGA). The pervaporation tests of our new AgNPs-PVA membranes show good results since at a higher temperature and higher ethanol concentration in the feed, the prepared membranes are highly permeable for the water having stable selectivity values and therefore our membranes show better performance compared to that of the other PVA-based nanocomposite membranes.

There are great interests to capture the CO₂ to control the greenhouse gas emission. Amine absorption of CO₂ is being taken as an effective way to capture CO₂ in industry. However, the amine absorption of CO₂ is cost-ineffective due to great energy consumption and solution consumption. In order to reduce the capture cost, catalyst fluidization is proposed here to intensify the mass transfer and heat transfer. Catalyst fluidization with field synergy and DFT model is developed by incorporating the effects of catalyst reaction kinetics, drag force and multi-field into the mass transfer, heat transfer, fluid flow and catalyst collision. Experiments with an improved distributor are performed well to validate the model. The reaction kinetics is determined by the DFT simulation and experiment. The mass transfer coefficient in the fluidized reactor is identified as 17% higher than the conventional packed reactor. With the field synergy of catalyst fluidization, the energy consumption for CO₂ desorption is reduced by 9%. Stepwise operation and inclination reactor are used to improve catalyst fluidization process.

This study involved the analysis and characterization of the multiphase flow phenomenon inside the lower stage cyclone separator used in the clinker burning process. The analysis was performed using both CFD and experimental research methods. Very few studies are devoted to such types of cyclone separators, which in addition to their basic functions are also responsible for the technological process. Due to the atypical working conditions of these cyclone separators, they are characterized with a complex geometry, which significantly differs from that of the traditional separators.
Furthermore, the evaluation of the accuracy and level of reliability of the two models of turbulence closure-k-ε RNG and RSM (RANS), and the LES. The results obtained led to the conclusion that for the lower stage cyclone separators, the LES model proved to be the most accurate (both in the case of forecasting the separation efficiency and pressure drop). The performance parameter (in particular the separation efficiency) values obtained for the RSM model were also characterized by high accuracy. The k-ε RNG model was characterized by significantly larger deviations.

Undoped and Ni-S co-doped mesoporous TiO₂ nano materials were synthesized by using sol-gel method. The characteristic features of as prepared catalyst samples were investigated using various advanced spectroscopic and analytical techniques. The characterization results of the samples revealed that all the samples exhibited anatase phase (XRD), decreasing band gap (2.68 eV) (UV-Vis-DRS), small particle size (9.2 nm) (TEM), high surface area (142.156 m²·g^-1) (BET), particles with spherical shape and smooth morphology (SEM); there is a frequency shift observed for co-doped sample (FT-IR) and the elemental composition electronic states and position of the doped elements (Ni and S) in the TiO₂ lattice analyzed by XPS and EDX. These results supported the photocatalytic degradation of Bismarck Brown Red (BBR) achieved with in 110 min and also exhibited the antibacterial activity on Staphylococcus aureus (MTCC-3160), Pseudomonas fluorescence (MTCC-1688) under visible light irradiation.

Source identification is critical for emergency responses to hazardous chemical releases, especially sudden releases of toxic gases. The timely arrangement of multiple sensors at the scene of a sudden accident is difficult. To overcome this limitation, a two-step source identification method based on a single sensor was developed. In the first step, the measured concentration was transmitted to the computing platform. First, a preliminary estimation of the release source was calculated from recently detected concentrations. Then, the preliminary result was used to predict the concentrations and to assess whether more measurements were needed. This data processing was conducted by the computing platform. In the second step, a new objective monitoring point was transmitted to the detector for the measurement of additional concentrations. These two steps were conducted repeatedly until the estimation adequately represented the release source. The fixed and mobile single sensor results were analyzed, and a comparison to multi-sensor results was also conducted. The results show that single-sensor source identification is attainable with a sufficient number of observations, and the number of valid concentration observations is required to be no less than the number of unknown parameters. To best estimate the release source, the movement strategy of the single sensor was based on the possible release source and the hazard partition of the gas plume. It is highly recommended that the single-sensor source identification method be used in unexpected incidents due to its flexibility and timely response.

To improve the efficiency of ethanol production in a batch fermentation from sweet sorghum juice under a very high gravity (VHG) condition (~290 g/L of total sugar) by Saccharomyces cerevisiae NP01, repeatedbatch fermentation under an aerated condition (2.5 vvm for the first 4 h during every cycle) was done in a 5-L fermenter. The average ethanol concentration (P), productivity (Q_p) and yield (Y_p/s) for five successive cycles were 112.31 g/L, 1.55 g/L·h^-1 and 0.44, respectively with 80.97% sugar consumption. To complete sugar consumption, the total sugar of the juice was reduced to a high gravity (HG) level (~240 g/L). The results showed that yeast extract was not necessary for ethanol production, and aeration during every other cycle i.e., alternating cycles, was sufficient to promote both yeast growth and ethanol production. The average P, Q_p and Y_p/s values for eight successive cycles with aeration during alternating cycles were 97.58 g/L, 1.98 g/L·h and 0.41, respectively with 91.21% sugar consumption. The total fatty acids in the yeast cells under the aerated condition were~50% higher than without aeration, irrespective the initial sugar concentration, whereas the ergosterol contents under aeration condition were~29% to 49% higher than those without aeration.

Concerns about feasibility, separability, settleability, efficiency once hampered studies on polyhydroxyalkanoates (PHAs) production, which mainly focused on single strain microorganism or activated sludge rather than artificial microbial consortia. Here, a medium chain length PHAs (mcl-PHAs) producing Pseudomonas-Saccharomyces consortium with xylose as the main substrate was studied. Mcl-PHAs accumulation increased from 12.69 mg·L^-1 to 152.3 mg·L^-1 without any optimization method. The presence of Saccharomyces cerevisiae, though in a relatively low concentration, improved the sedimentation of cell mass of the mixed culture by 60%. Reasons for better sedimentation of the consortium were complex:first, the length of Pseudomonas putida increased two to three times in the consortium; second, the positive surface charge of P. putida was neutralized by S. cerevisiae; third, the adhesion proteins on the surface of S. cerevisiae interacted with the P. putida.

An experimental study on co-pyrolysis of bituminous coal and biomass was performed in a pressured fluidized bed reactor. The blend ratio of biomass in the mixture was varied between 0 and 100 wt%, and the temperature was over a range of 550-650℃ under 1.0 MPa pressure with different atmospheres. On the basis of the individual pyrolysis behavior of bituminous coal and biomass, the influences of the biomass blending ratio, temperature, pressure and atmosphere on the product distribution were investigated. The results indicated that there existed a synergetic effect in the co-pyrolysis of bituminous coal and biomass in this pressured fluidized bed reactor, especially when the condition of bituminous coal and biomass blend ratio of 70:30 (w/w), 600℃, and 0.3 MPa was applied. The addition of biomass influenced the tar and char yields and gas and tar composition during co-pyrolysis. The tar yields were higher than the calculated values from individual pyrolysis of each fuel, and consequently the char yields were lower. The experimental results showed that the composition of the gaseous products was not in accordance with those of their individual fuel. The improvement of composition in tar also indicated synergistic effect in the co-pyrolysis.

This paper proposes a novel method relating to the recycling of waste lead ash originated from procedure of lead alloy production. The spent lead ash was first disposed by acetic acid leaching system, where lead ash structure wrapping impurities would be destroyed. The synthesis of lead oxide products was conducted at a lower temperature of 90℃. The effect of molar ratio of CH₃COOH to lead content of the ash on leaching efficiency was studied through the acetic acid leaching system. The results demonstrate that 84.6% of lead could be obtained in the leaching solution, while merely 0.7% of Fe blend in solution within a leaching time of 120 min. In the stage of lead oxide synthesis from leaching solution, the yield of lead oxide products could reach up to 94.4% when the molar ratio of NaOH to lead in filtrate was 2.5. This novel green method could shed light on the reuse of lead from exhausted ash with a much more convenient and environmentally friendly procedure.

The present work investigated the synergetic effect of pyrolysis-derived char, tar and gas (py-gas) on NO reduction, which may occur in circulating fluidized-bed decoupling combustion (CFBDC) system treating N-rich fuel. Experiments were carried out in a lab-scale drop-tube reactor for NO reduction by some binary mixtures of reagents including char/py-gas, tar/py-gas and tar/char. At a specified total mass rate of 0.15 g·min^-1 for NO-reduction reagent, the char/py-gas (binary reagent) enabled the best synergetic NO reduction in comparison with the others. There existed effective interactions between char and some species in py-gas (i.e., H₂, C_xH_y) during NO reduction by pyrolysis products, meanwhile the tar/py-gas or tar/char mixture only caused a positive effect when tar proportion was necessarily lowered to about 26%. On the other hand, the synergetic effects were not improved for all tested binary reagents by increasing the reaction temperature and residence time.

The performances of the response surface methodology (RSM) in connection with the Box-Behnken, face central composite or full factorial design (BBD, FCCD or FFD, respectively) were compared for the use in modeling of the NaOH-catalyzed sunflower oil ethanolysis. The influence of temperature, catalyst loading, and ethanol-to-oil molar ratio (EOMR) on fatty acid ethyl esters (FAEE) content was evaluated. All three multivariate strategies were efficient in the statistical modeling and optimization of the influential process variables but BBD and FCCD realization involved less number of experiments, generating smaller costs, requiring less work and consuming shorter time than the corresponding FFD. All three designs resulted in the same optimal catalyst loading (1.25% of oil) and EOMR (12:1). The reduced two-factorinteraction (2FI) models based on the BBD and FCCD defined a range of optimal reaction temperature (25℃-75℃) and 25℃, respectively while the same model based on the 3³ FFD appointed 75℃. The predicted FAEE content of about 97%-98.0% was close to the experimentally obtained FAEE content of about 97.0%-97.6% under the optimal reaction conditions. Therefore, the simpler BBD or FCCD might successfully be applied for statistical modeling of biodiesel production processes instead of the more extensive, more laborious and more expensive FFD.

Carbonated water injection (CWI) is known as an efficient technique for both CO₂ storage and enhanced oil recovery (EOR). During CWI process, CO₂ moves from the water phase into the oil phase and results in oil swelling. This mechanism is considered as a reason for EOR. Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials. Generally, instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon. Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery reduction. Therefore, higher in-situ water content can worsen this condition. Besides, this water can play as a barrier between oil and gas phases and adversely affect the gas diffusion, which results in EOR reduction. On the other hand, from gas storage point of view, it should be noted that CO₂ solubility is not the same in the water and oil phases. In this study for a specified water salinity, the effects of different connate water saturations (S_wc) on the ultimate oil recovery and CO₂ storage capacity during secondary CWI are being presented using carbonate rock samples from one of Iranian carbonate oil reservoir. The results showed higher oil recovery and CO₂ storage in the case of lower connate water saturation, as 14% reduction of S_wc resulted in 20% and 16% higher oil recovery and CO₂ storage capacity, respectively.

In this work, microwave treatment was introduced to a hydrothermal treatment process to degrade PCDD/Fs (Polychlorinated dibenzo-p-dioxins and dibenzofurans) in municipal solid waste incineration (MSWI) fly ash. Three process additives (NaOH, Na₂HPO₄, H₂O), temperatures (150℃, 185℃, 220℃) and reaction times (1 h, 2 h, 3 h) were investigated to identify their effect on the disposal of fly ash samples through orthogonal experiments. High-resolution gas chromatography-mass spectrometry (HRGC/MS) was applied to determine the PCDD/F concentrations in MSWI fly ash. The experimental results revealed that 83.7% of total PCDD/Fs was degraded. Reaction temperature was the most important factor for the degradation of the total PCDD/Fs. Both direct destruction and chlorination reactions (the chlorination degree of PCDFs increased) took part in the degradation of PCDD/Fs in fly ash, which was a new discovery. Several PCDD/F indexes determined by the concentration of indicative congeners were found to quantitatively characterize the dioxin toxicity of the fly ash. Furthermore, heavy metals in the fly ash sample were solidified using microwave-assisted hydrothermal treatment, which provided an experimental basis for the simultaneous disposal of dioxins and heavy metals. Thus, the microwave-assisted hydrothermal process should be considered for the future disposal of MSWI fly ash.

Malaysian Selantik low-rank coal (SC) was used as a precursor to prepare a form of mesoporous activated carbon (SC-AC) with greater surface area (SA) via a microwave induced KOH-activation method. The characteristics of the SC and SC-AC were evaluated by the iodine number, ash content, bulk density, and moisture content. The structure and surface characterization was carried out using pore structure analysis (BET), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), elemental analysis (CHNS), thermogravimetric analysis (TGA), and determination of the point of zero charge (pH_PZC). These results signify a mesoporous structure of SC-AC with an increase of ca. 1160 times (BET SA=1094.3 m²·g^-1) as compared with raw SC without activation (BET SA=1.23 m²·g^-1). The adsorptive properties of the SC-AC with methylene blue (MB) was carried out at variable adsorbent dose (0.2-1.6 g·L^-1), solution pH (2-12), initial MB concentrations (25-400 mg·L^-1), and contact time (0-290 min) using batch mode operation. The kinetic profiles follow pseudo-second order kinetics and the equilibrium uptake of MB conforms to the Langmuir model with a maximum monolayer adsorption capacity of 491.7 mg·g^-1 at 303 K. Thermodynamic functions revealed a spontaneous endothermic adsorption process. The mechanism of adsorption included mainly electrostatic attractions, hydrogen bonding interaction, and π-π stacking interaction. This work shows that Malaysian Selantik low-rank coal is a promising precursor for the production of low-cost and efficient mesoporous activated carbon with substantive surface area.

Slagging is a major problem in boilers, especially the low-rank coal applied in boilers. In this study, the influence of heat transfer surface on the slagging characteristics of a pilot-scale furnace was investigated. Ni coatings were applied in modifying the deposition surface to control slagging. The growth characteristics of the slag were studied using an online digital image technique. Scanning electron microscopy linked with energy-dispersive X-ray analysis and X-ray diffraction (XRD) were applied to investigate the microstructure, semi-quantitative chemical composition, and mineralogy of slag samples. Ni coating demonstrated a positive effect on the mitigation of slagging. Results revealed that the thicknesses of the slag initially increased with experimental time and then inclined toward stable values for both cases (Case 1:substrate material; Case 2:modified surface). The stable thicknesses for Cases 1 and 2 were 4.91 mm and 3.95 mm, respectively. The heat transfer efficiency was improved by approximately 18.2% with the application of Ni coating for probe surface modification. The mechanism of the mitigation of slagging was investigated in this study. XRD results revealed that the content of alkali reduced when the surface was coated with Ni. The alkali significantly affected the adhesion behavior of the deposition. Hence, Ni coating showed potential in reducing slagging and increasing the efficiency of boilers. The overall study makes a contribution to a deep understanding of the effect of Ni coating on the growth characteristics of the slag.

Dipentaerythritol (DPER), 4, 40-diphenylmethanediisocyanate (MDI) and melamine (MEL) are used as raw materials to microencapsulate ammonium polyphosphate (MAPP) in situ polymerization. The MAPP is characterized by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermal gravimetric analysis (TGA). The results show that the coating operation can effectively improve water resistance of ammonium polyphosphate (APP), and MAPP has higher residual rate than that of APP after combustion. The flame retardant action of MAPP and APP in polypropylene (PP) is investigated by the limited oxygen index (LOI), vertical burning test (UL-94), TGA, SEM, and cone calorimeter test (CCT). The LOI value of the PP/MAPP composite at the same loading is higher than that of PP/APP composite. UL 94 ratings of PP/MAPP composites are raised to V-0 at 20 wt% loading. The results of CCT also show that MAPP is more efficient than APP. The morphological structures observed by digital photos and SEM demonstrated that MAPP could be promoted to form the continuous and compact intumescent char layer. The flame retardant mechanism of PP/MAPP is also discussed.