•Propose two phenol removal processes with heat integration based on industrialized case.•These two processes are proven to be promising with high energy saving by 18%.•Few additional capital cost is required, while high treatment cost is saved.Coal gasification wastewater treatment process, especially for the wastewater produced by pressurized fixed bed gasification, has already become one of the key factors which restrict the development of coal chemical industry. This wastewater has all along been regarded as one of the most difficult to be treated with because of the high concentration of phenol and ammonia in it. The most efficient treatment method is distillation and extraction. Phenols and ammonia are recovered as products. However, energy consumption, in the form of low-pressure steam and mid-pressure steam, is relatively high in this process. Technological and economic performance of the wastewater treatment process developed by South China University of Technology (SCUT) was analyzed in this paper. Two integration processes based on SCUT wastewater treatment process are proposed in which solvent recovery system is thermally integrated. The results indicate that the energy consumption via these integrations is decreased by approximately 18% compared with the conventional SCUT process. The cost of wastewater treatment can be reduced to 0.2 CNY/ton of wastewater. An on-site trial-plant is constructed to test the feasibility of the processes. The competitiveness of the technology for wastewater treatment is improved.Download high-res image (115KB)Download full-size image

The hydrogen to carbon (H/C) ratio of coal gasified gas in the range 0.2–1.0, far less than the desired value for the coal to methanol process. Therefore, a water gas shift unit is needed to raise the H/C ratio, which results in a great deal of CO2 emission and carbon resource waste. At the same time, there is 7 × 1010 m3 coke-oven gas (COG) produced in coke plants annually in China. The hydrogen-rich COG consists of 60% hydrogen and 26% methane. However, a massive amount of COG is utilized as fuel or discharged directly into the air, which makes a waste of precious hydrogen resources and causes serious environmental pollution. This paper proposes an integrated process of coke-oven gas and coal gasification to methanol, in which a tri-reforming reaction is used to convert methane and CO2 to syngas. The carbon utilization and energy efficiency of the new process increase about 25% and 10%, whereas CO2 emission declines by 44% in comparison to the conventional coal to methanol process.

In recent years, developing alternative liquid to fossil fuels has drawn much attention from world industry. In China, the coal/biomass-based Fischer–Tropsch (FT) liquid is a promising alternative to address the shortage of petroleum supplies. However, there is a lack of systematic and quantitative assessment of sustainability of these processes. This paper proposes a multi-dimensional set of metrics to assess sustainability performance of the coal/biomass to FT liquids processes in China. The assessment indicates that the coal-to-FT fuel process performs well in technical and economic aspects, while unsatisfactorily in relation to environmental features. Besides, the production potential of coal-to-FT in China by 2020 is rather limited. On the other hand, the biomass-to-FT fuel process shows great potential for replacement of petroleum-derived fuels and good environmental performance, although it does not perform well in terms of economic and technical characteristics at present. Co-processing biomass with coal to make FT fuel is a preferable compromise option for its low GHG emissions and good economic performance, although further investigations and technical improvements are needed.Keywords: Biomass-to-liquid; Coal-to-liquid; Fischer−Tropsch synthesis; Metrics; Sustainability assessment

The conventional oil shale refinery suffers from inefficiency in resource use and poor economic performance. This is because that detrital oil shale and retorting gas are not properly used. Hydrogenation of crude shale oil is not cost-efficient with outsourcing hydrogen. Proposed in this paper is an integrated oil shale refinery with reforming of the retorting gas. The retorting gas is used to produce hydrogen, which is then supplied for the hydrogenation. Crude shale oil is upgraded to higher valued products, such as naphtha, diesel, and liquefied petroleum gas. The detrital oil shale is combusted to provide heat for the regeneration of CaO. Economic analysis is conducted by comparing to the conventional refinery process. Results show that the return on investment of the proposed process is 18.89%, much higher than the previous 10.53% of the conventional refinery process.

Ecologically based life cycle assessment (Eco-LCA) is an appealing approach for the evaluation of resources utilization and environmental impacts of the process industries from an ecological scale. However, the aggregated metrics of Eco-LCA suffer from some drawbacks: the environmental impact metric has limited applicability; the resource utilization metric ignores indirect consumption; the renewability metric fails to address the quantitative distinction of resources availability; the productivity metric seems self-contradictory. In this paper, the existing Eco-LCA metrics are revised and extended for sustainability assessment of the energy and chemical processes. A new Eco-LCA metrics system is proposed, including four independent dimensions: environmental impact, resource utilization, resource availability, and economic effectiveness. An illustrative example of comparing assessment between a gas boiler and a solar boiler process provides insight into the features of the proposed approach.

Olefins have been regarded as one of the most important platform chemicals. The production of olefins and their derivatives are highly subject to oil. Developing coal-to-olefins processes is therefore of great interest to many countries, especially China. However, people have to face and pay for the severe environmental problems resulting from coal-to-olefins development. Of these problems, high CO2 emission of a coal-to-olefins process, always attracts the most attention since it is about five to six times of that of an oil-to-olefins process. For this problem, this paper proposes a new natural gas assisted coal-to-olefins process integrating CO2 recovery gasification and CH4/CO2 reforming techniques. The former technique increases the amount of syngas from the gasifier, while the latter one uses additional natural gas reacting with CO2 to produce H2-rich syngas. Key parameters are studied during the simulation of the new process. The advantages of the process are manifested by comparison with a conventional coal-to-olefins process from the techno-economic point of view. Results show that the new process is promising since it reduces the CO2 emission by 29.9% and increases the carbon efficiency and the energy efficiency by 20.7% and 7.8%. With the high market price of natural gas, the product cost of the new process is slightly higher than the coal-to-olefins process. But the new process will be more competitive if considering that the carbon tax is larger than $18.2/t CO2 or that shale gas is available in China.

A systematic multiscale method is presented for studying the structure–performance relationship of drug-delivery systems (DDSs). The objective is to provide direction and guidelines toward the design and development of novel DDSs. Atomic simulation methods are used to evaluate the interactions between each pair of components in a DDS, from which the compatibility between drug and carriers can be well-predicted. Mesoscale simulation is applied to investigate the mesostructures of DDSs, from which the performances of products can be predicted. Finally, the drug-loaded nanoparticles can be prepared and evaluated through experiments involving loading efficiency, drug-release behaviors, and so on. The hydrophobic drugs doxorubicin and paclitaxel were considered as examples. The multiscale approach was used to investigate the structure–performance relationship of DDSs for these two drugs. All of the experimental results agreed well with the simulation results, indicating that the systematic multiscale method can provide a powerful tool for designing and developing DDSs.

A framework is proposed for integration of unit modeling, process synthesis, analysis, optimization, and process design of coal gasification-based energy and chemical processes. The conceptual models of these processes are built by the modeling and synthesis blocks in the framework, which are the bases of analysis and optimization. A number of analysis techniques are employed in the framework to fully understand the characteristics of the processes and their performances from technical, economic, and environmental points of view. Life cycle assessment and sustainability analysis are also included in the framework. According to these multilayer analyses, optimization is included in this framework to explore the best process or the best operational parameter set. Because of the systematic integration of the above techniques, the proposed framework could provide a comprehensive study for coal gasification-based processes. Three coal gasification-based processes are selected as the study cases in this Article. They are an integrated gasification combined cycle process, a methanol production, and a coproduction process combining the first two processes. The exergy efficiencies and economic investments of the three processes are analyzed and compared. The key parameters for material distribution in the coproduction process are optimized from the exergy efficiency and the investment points of view.

Coal-gasification wastewater poses serious problems in the Lurgi process. It cannot be easily purified, as the high pH value of the wastewater limits the dephenolization efficiency of extraction. This work proposes a new process to remove ammonia and sour gas in order to reduce the pH value of the wastewater from 9 to below 7, and next to remove phenol with solvent extraction under acidic conditions. This new process consists of a wastewater stripper with side-draw to remove ammonia and sour gas, an extractor to remove phenol, and two distillation columns to recover extractant. Process simulation was conducted to study the performance of the new process and to perform a detailed design. The complex multicomponent system NH3−CO2−H2S−NaOH−phenol−H2O was analyzed when simulating the wastewater stripping. The new process has been successfully implemented in an industrial installation for coal-gasification wastewater treatment with a capacity of 2000 tons/day. Satisfactory agreement was obtained between the simulation results and the industrial implementation of the new process. The new process, when compared with the old one, recovers phenols more efficiently and produces a wastewater stream acceptable for later biological treatment.

Dissipative particle dynamics simulations were performed to study the microstructures of doxorubicin (DOX) loaded/blank micelles self-assembled from cholesterol conjugated His10Arg10 (HR20-Chol) at different pH conditions. DOX molecules can be efficiently encapsulated in the core of micelles. At pH > 6.0, these micelles have stronger DOX loading ability due to the hydrophobicity of histidine residues, as compared to that of pH < 6.0. With the decrease of pH from pH > 6.0 to pH < 6.0, the structure of micelles trends to be swelling from dense conformations. This structural transformation can facilitate the release of DOX from the core of micelles. All the simulation results are qualitatively consistent with the experimental results, demonstrating that the DPD method may provide a powerful tool in analysis and design of drug delivery systems.

The solubility of folic acid in water was measured at pH values between 0 and 7 at the temperatures (298.15, 303.15, and 313.15) K using a standard shake and settle method with analysis by high-performance liquid chromatography (HPLC). A temperature and dissociation constant related solubility model was built to describe the folic acid solubility performance, and the experimental data matched the model well with a square of the multiple correlation coefficient (R2) of 0.9900.

A large amount of wastewater is produced in the Lurgi coal-gasification process with the complex compounds carbon dioxide, ammonia, phenol, etc., which cause a serious environmental problem. Most of the known pretreatment techniques do not yield sufficient performance for phenol removal, which hampers the functions of the subsequent biochemical treatment process. In this paper, a novel stripper operated at elevated pressure is designed to improve the pretreatment process. In this technology, two noticeable improvements were established. First, the carbon dioxide and ammonia were removed simultaneously in a single striper where sour gas (mainly carbon dioxide) is removed from the tower top and the ammonia vapor is drawn from the side and recovered by partial condensation. Second, the ammonia is removed before the phenol recovery to reduce the pH value of the subsequent extraction units, so as the phenol removal performance of the extraction is greatly improved. To ensure the operational efficiency, some key operational parameters are analyzed and optimized though simulation. It is shown that when the top temperature is kept at 40 °C and the weight ratio of the side draw to the feed is above 9%, the elevated pressures can ensure the removal efficiency of NH3 and carbon dioxide and the desired purified water as the bottom product of the unit is obtained. A real industrial application demonstrates the attractiveness of the new technique: it removes 99.9% CO2 and 99.6% ammonia, compared to known techniques which remove 66.5% and 94.4%, respectively. As a result, the pH value of the wastewater is reduced from above 9 to below 7. This ensures that the phenol removal ratio is above 93% in the following extraction units. The operating cost is lower than that of known techniques, and the operation is simplified.

It is shown in this paper that by changing the initial operation condition of batch processes, the dynamic performance of the system can be varied largely. The initial operation conditions are often ignored in design of batch processes for flexibility against disturbances or parameter variations. When the initial conditions are not rigid, as in the case of a batch reactor where the initial reaction temperature is quite arbitrary, optimization can also be applied to determine the “best” initial condition to be used. Problems for dynamic flexibility analysis, including initial conditions and process operation, can be formulated as dynamic optimization problems. If the initial conditions are considered, the conditions can be transferred into control variables in the first step of optimization. The solution of the dynamic optimization is based on the Runge-Kutta integration algorithm and decomposition search algorithm. This method, as illustrated and tested with two highly nonlinear chemical engineering problems, enables the optimal solution to be determined.

DPD simulations were employed to study the phase behavior of paclitaxel loaded PEO11-b-PLLA9 in water and N,N-Dimethylformamide. Different ordered structures were observed in water-rich solvents. All the structures were greatly affected by solvents compositions. By varying the fractions of each component, a phase diagram of paclitaxel loaded PEO11-b-PLLA9 in water and DMF was mapped. For all ordered structures, bicontinuous, lamella, rod, and spherical structures with different sizes could be easily observed for their wide distribution in the phase diagram. While the HPL, dumbbell, and spherical structures with uniform size were difficult to be obtained, due to their narrow distribution.A phase diagram of paclitaxel loaded PEO11-b-PLLA9 in water and DMF was mapped through dissipative particle dynamics, which may provide a powerful tool for designing drug delivery systems.

A systematic procedure is presented for selecting the carrier material and stabilizer for drug-loaded solid lipid microparticles (SLMs). Heuristics criteria as well as investigation methods are proposed. The proposed procedure is based on the summaries of the authors’ investigation and the accumulated heuristics derived from the available literature works. The physical properties of carrier materials, drug distribution in the carrier matrix, the compatibility between drugs and carrier materials, and the crystal structures of carrier matrices are taken into account in the selection of the carrier materials. In stabilizer selection, the coverage of stabilizer molecules on particle surfaces and the electrostatic repulsion and steric repulsion of stabilizers should be considered. The presented heuristics and criteria are to assist with decision making in new SLM development. This is demonstrated with an application case, in which a clozapine-loaded SLM formulation is designed, to illustrate the selection of carrier materials and stabilizers. Experiments and testing have confirmed the effectiveness of the proposed procedure and heuristics.

Nonlinear model predictive control (NMPC) is an appealing control technique for improving the performance of batch processes, but its implementation in industry is not always possible due to its heavy on-line computation. To facilitate the implementation of NMPC in batch processes, we propose a real-time updated model predictive control method based on state estimation. The method includes two strategies: a multiple model building strategy and a real-time model updated strategy. The multiple model building strategy is to produce a series of simplified models to reduce the on-line computational complexity of NMPC. The real-time model updated strategy is to update the simplified models to keep the accuracy of the models describing dynamic process behavior. The method is validated with a typical batch reactor. Simulation studies show that the new method is efficient and robust with respect to model mismatch and changes in process parameters.

A novel process to recovery natural gas liquids from oil field associated gas with liquefied natural gas (LNG) cryogenic energy utilization is proposed. Compared to the current electric refrigeration process, the proposed process uses the cryogenic energy of LNG and saves 62.6% of electricity. The proposed process recovers ethane, liquid petroleum gas (propane and butane) and heavier hydrocarbons, with total recovery rate of natural gas liquids up to 96.8%. In this paper, exergy analysis and the energy utilization diagram method (EUD) are used to assess the new process and identify the key operation units with large exergy loss. The results show that exergy efficiency of the new process is 44.3%. Compared to the electric refrigeration process, exergy efficiency of the new process is improved by 16%. The proposed process has been applied and implemented in a conceptual design scheme of the cryogenic energy utilization for a 300 million tons/yr LNG receiving terminal in a northern Chinese harbor.

Chemical batch processes have become significant in chemical manufacturing. In these processes, largenumbers of chemical products are produced to satisfy human demands in daily life. Recently, economy globalization has resulted in growing worldwide competitions in traditional chemical process industry. In order to keep competitive in the global marketplace, each company must optimize its production management and set up a reactive system for market fluctuation. Scheduling is the core of production management in chemical processes. The goal of this paper is to review the recent developments in this challenging area. Classifications of batch schedulingproblems and optimization methods are introduced. A comparison of six typical models is shown in a general benchmark example from the literature. Finally, challenges and applications in future research are discussed.

This paper presents a novel cleaner production process for producing sodium chlorite by reducing sodium chlorate with hydrogen peroxide. In the new process, chlorine dioxide is generated by reducing chlorate ions with hydrogen peroxide in the presence of sulfuric acid: it then reacts with aqueous sodium hydroxide solution and hydrogen peroxide to produce sodium chlorite. The reaction conditions that were experimentally investigated included: reaction temperatures, concentrations of sodium chlorate solution, molar ratio of NaClO3:H2SO4:H2O2, and acidity. Waste acid in the chlorine dioxide generator is dramatically reduced with recycling in the new process. The by-produced sodium sulfate in sulfuric acid is minimized and reclaimed.

•Environmental and techno-economic performance of coal gasification processes is analyzed.•Three scenarios of coal gasification process with/without CO2 capture are developed.•The process with CO2 capture and utilization has better performance if carbon tax is considered.Coal gasification, the technology for high-efficient utilization of coal, has been widely used in China. However, it suffers from high CO2 emissions problem due to the carbon-rich character of coal. To reduce CO2 emissions, different CO2 capture technologies are developed and integrated into the coal gasification based processes. However, involving CO2 capture would result in energetic and economic penalty. This paper analyses three cases of coal gasification processes from environmental, technical, and economical points of view. These processes are (1) a conventional coal gasification process; (2) a coal gasification process with CO2 capture and sequestration, in which CO2 is stored by mineral sequestration; (3) a coal gasification process with CO2 capture and utilization, in which CO2 is reused to produce syngas. The results show that the coal gasification process with CO2 capture and sequestration has advantage only in environmental aspect compared to the conventional process. The process with CO2 capture and utilization has advantages in both technical and environmental aspects while disadvantage in economic aspect. However, if the carbon tax higher than 15 USD/t CO2 is introduced, this disadvantage will be negligible.* 0 is the worst case, whilst 100 is the best case in the figure.Download full-size image

Many continuous-time formulations have been proposed during the last decades for short-term scheduling of multipurpose batch plants. Although these models establish advantages over discrete-time representations, they are still inefficient in solving moderate-size problems, such as maximization of profit in long horizon, and minimization of makespan. Unlike existing literature, this paper presents a new precedence-based mixed integer linear programming (MILP) formulation for short-term scheduling of multipurpose batch plants. In the new model, multipurpose batch plants are described with a modified state-task network (STN) approach, and binary variables express the assignments and sequences of batch processing and storing. To eliminate the drawback of precedence-based formulations which commonly include large numbers of batches, an iterative procedure is developed to determine the appropriate number of batch that leads to global optimal solution. Moreover, four heuristic rules are proposed to selectively prefix some binary variables to 0 or 1, thereby reducing the overall number of binary variables significantly. To evaluate model performance, our model and the best models reported in the literature (S&K model and I&F model) are utilized to solve several benchmark examples. The result comparison shows that our model is more effective to find better solution for complex problems when using heuristic rules. Note that our approach not only can handle unlimited intermediate storage efficiently as well as the I&F model, but also can solve scheduling problems in limited intermediate storage more quickly than the S&K model.