基于高阶统计和解释结构模型相结合的大型过程控制系统的故障检测(英文)

Nonlinear characteristic fault detection and diagnosis method based on higher-order statistical (HOS) is an effec-tive data-driven method, but the calculation costs much for a large-scale process control system. An HOS-ISM fault diagnosis framework combining interpretative structural model (ISM) and HOS is proposed:(1) the adja-cency matrix is determined by partial correlation coefficient;(2) the modified adjacency matrix is defined by directed graph with prior knowledge of process piping and instrument diagram;(3) interpretative structural for large-scale process control system is built by this ISM method;and (4) non-Gaussianity index, nonlinearity index, and total nonlinearity index are calculated dynamical y based on interpretative structural to effectively eliminate uncertainty of the nonlinear characteristic diagnostic method with reasonable sampling period and data window. The proposed HOS-ISM fault diagnosis framework is verified by the Tennessee Eastman process and presents improvement for highly non-linear characteristic for selected fault cases.     

多变量统计过程监控:进展及其在化学工业的应用

Multivariate statistical process monitoring and control (MSPM&C) methods for chemical process monitoring with statistical projection techniques such as principal component analysis (PCA) and partial least squares (PLS) are surveyed in this paper. The four-step procedure of performing MSPM&C for chemical process, modeling of processes, detecting abnormal events or faults, identifying the variable(s) responsible for the faults and diagnosing the source cause for the abnormal behavior, is analyzed. Several main research directions of MSPM&C reported in the literature are discussed, such as multi-way principal component analysis (MPCA) for batch process, statistical monitoring and control for nonlinear process, dynamic PCA and dynamic PLS, and on-line quality control by inferential models. Industrial applications of MSPM&C to several typical chemical processes, such as chemical reactor, distillation column, polymerization process, petroleum refinery units, are summarized. Finally, some concluding remarks an     

Design of a modern automatic control system for the activated sludge process in wastewater treatment

The Activated Sludge Process (ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a chal enging matter. The proposed control method is an I-P modified controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms, (reference value step increase of 50 mg·L?1) and 0.01 days for the concentration of oxygen (reference value step increase of 0.1 mg·L?1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of 5 × 103m3·d?1 are smal . Changes in the reference values of oxygen and microorganisms (increases by 10%, 20%and 30%) show satisfactory response of the system in al cases. Changes in the value of inlet wastewater flow rate disturbance (increases by 10%, 25%, 50%and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25%which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI control er. This method can substitute optimal control systems in ASP.     

面向可持续发展的半导体制造的集成产品和过程控制

Semiconductor fabrication is a manufacturing sequence with hundreds of sophisticated unit operations and it is always challenged by strategy development for ensuring the yield of defect-free products. In this paper, an advanced control strategy through integrating product and process control is established. The proposed multiscale scheme contains three layers for coordinated equipment control, process control and product quality control. In the upper layer, online control performance assessment is applied to reduce the quality variation and maximize the overall product performance (OPP). It serves as supervisory control to update the recipe of the process controller in the middle layer. The process controller is designed as an exponentially weighted moving average (EWMA) run-to-run controller to reject disturbances, such as process shift, drift and tool worn out, that are exerted to the op-eration. The equipment in the process is individually controlled to maintain its optimal operational status and maximize the overall equipment effectiveness (OEE), based on the set point given by the process controller. The ef-ficacy of the proposed integrated control scheme is demonstrated through case studies, where both the OPP (for product) and the OEE (for equipment) are enhanced.     

具有固定硅铝比的Al2O3-2SiO2纳米颗粒制备:过程优化与粉体转化（英文）

Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane(TEOS) and aluminum nitrate(ANN) as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure(morphology) of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows:the molar ratio of water and ethanol to TEOS are 0:1 and 12:1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m2·g·1.The compressive strength of the geopolymer and the calcium exchange capacity(by CaCO3) of NaA zeolite prepared with the powders reached to 29 MPa and 366 mg·g·1 respectively.     

MPC of distillation column with side reactors for methyl acetate

This paper focuses on the dynamic control of distillation column with side reactors(SRC)for methyl acetate pro-duction.To obtain the optimum integrated structure and steady state simulation,the systematic design approach based on the concept of independent reaction amount is applied to the process of SRC for methyl acetate produc-tion.In addition to the basic control loops,multi-variable model predictive control modular with methyl acetate concentration and temperature of sensitive plate is designed.Then,based on process simulation software Aspen Plus,dynamic simulation of SRC for methyl acetate production is used to verify the effectiveness of the control scheme.     

苯氯化侧反应精馏过程的系统设计与控制(英文)

The distillation column with side reactors (SRC) can overcome the temperature/pressure mismatch in the traditional reactive distillation, the column operates at temperature/pressure favorable for vapor-liquid separation, while the reactors operate at temperatures/pressures favorable for reaction kinetics. According to the smooth operation and automatic control problem of the distillation column with side reactors (SRC), the design, simulation calculation and dynamic control of the SCR process for chlorobenzene production are discussed in the paper. Firstly, the mechanism models, the integrated structure optimal design and process simulation systems are established, respectively. And then multivariable control schemes are designed, the controllability of SRC process based on the optimal steady-state integrated structure is explored. The dynamic response performances of closed-loop system against several disturbances are discussed to verify the effectiveness of control schemes for the SRC process. The simulating results show that the control structure using conventional control strategies can effectively overcome feeding disturbances in a specific range.     

KINETICS OF THE EXTRACTION OF COBALT WITH EXTRACTANT P5709

The kinetics of extraction of cobalt with P5709 was studied in a Lewis cell. In the extraction system the aqueous phase was the solution of CoSO_4 (8.8×10~(-4)—3.4×10~(-2)M) and Na_2SO_4 (0.63M.) at pH 5.5; the organic phase was 15% (v/v) P5709 in kerosene (saturated with hydrogen).In order to determine the control regime of extraction of cobalt, the stirring speed, the interracial area between the two phases and the operating temperature were varied in the experiments. Experimental results showed that the extraction process of cobalt was predominantly governed by the diffusion process, and the overall mass transfer coefficients were found to be as follows:_((a)): (2-5)×10~(-3)cm/s, _((o)): (0.3-1)×10~(-3)cm/s.The results of the experiments and calculations indicated that K did not remain constant during the extraction process, Reasons for the variations in K were discussed.     

旋风分离技术研究进展(英文)

Centered on the techniques and industrial applications of the reinforced cyclonic separation process,its principles and mechanism for separation of ions,molecules and their aggregates using polydisperse droplets are discussed generally;the characteristics and influential factors of fish-hook phenomenon of the grade efficiency curve in cyclonic separation for both gas and liquid are analyzed;and the influence of shear force on particle behavior(or that of particle swarm) is also summarized.A novel idea for cyclonic separation is presented here:enhancing the cyclonic separation process of ions,molecules and their aggregates with monodisperse microspheres and their surface grafting,rearranging the distribution of particles by size using centrifugal field,reinforcing the cyclonic separation performance with orderly arranged particle swarm.Also the investigation of the shortcut flow,recirculation flow,the asymmetric structure and non-linear characteristics of the cyclonic flow field with a combined method of Volumetric 3-component Velocimetry(V3V) and Phase-Doppler Particle Anemometer(PDPA) are elaborated.It is recommended to develop new systems for the separation of heterogeneous phases with cyclonic technology,in accordance with the capture and reuse of CO 2,methanol to olefins(MTO) process,coal transfer,and the exploitation of oil shale.     

SBR工艺除磷过程与种群结构在线监测

For efficient energy consumption and control of effluent quality, the cycle duration for a sequencing batch reactor (SBR) needs to be adjusted by real-time control according to the characteristics and loading of wastewater. In this study, an on-line information system for phosphorus removal processes was established. Based on the analysis for four systems with different ecological community structures and two operation modes, anaerobic-aerobic process and anaerobic-anaerobic process, the characteristic patterns of oxidation-reduction potential (ORP) and pH were related to phosphorous dynamics in the anaerobic, anoxic and aerobic phases, for determination of the end of phosphorous removal. In the operation mode of anaerobic-aerobic process, the pH profile in the anaerobic phase was used to estimate the relative amount of phosphorous accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs), which is beneficial to early detection of ecology community shifts. The on-line sensor values of pH and ORP may be used as the parameters to adjust the duration for phosphorous removal and community shifts to cope with influent variations and maintain appropriate operation conditions.     

三聚氰胺净化湿法磷酸第二阶段反应动力学

研究了三聚氰胺结晶法净化湿法磷酸生产磷酸钠盐的第二阶段反应过程动力学特征，测定了反应过程的动力学数据。在液固反应扩散传质控制条件下，确定了反应过程的动力学方程为１－３（１－ＸＢ）Ｂ２３＋２（１－ＸＢ）＋ｋ∫ｔ０ＣＡＬｄｔ。式中ｋ符合Ａｒｈｅ－ｎｉｕｓ关系：ｋ＝６．１０×１０－３ｅｘｐ［－５．５２９／（ＲＴ）］。对模型的检验结果表明所得动力学模型的置信度在９５％以上。     

Fault detection of large-scale process control system with higher-order statistical and interpretative structural model

Nonlinear characteristic fault detection and diagnosis method based on higher-order statistical (HOS) is an effec-tive data-driven method, but the calculation costs much for a large-scale process contr...     

碳酸氢钠调控五水碳酸镁的合成

在NaHCO₃调控作用下, 通过MgCl₂和Na₂CO₃反应结晶合成了五水碳酸镁(MgCO₃·5H₂O)。利用SEM、XRD和TG等技术, 结合反应结晶过程中镁离子浓度变化, 研究了工艺参数对结晶过程和产物影响。实验结果表明, 合成五水碳酸镁过程中极易生成MgCO₃·3H₂O副产物。纯MgCO₃·5H₂O制备工艺条件为:NaHCO₃加入量≥3.00 g·L^-1, 碳酸钠加料速率2～50 ml·min^-1, 合成温度0～5.0℃。所合成的五水碳酸镁呈棱柱状形貌, 晶体表面光滑, 尺寸20～160 μm。分析表明, 添加碳酸氢钠促进了结晶动力学, 同时 基团对三水碳酸镁晶体的形成具有位阻效应, 但有利于五水碳酸镁晶体形成, 产生晶型调控的协同效果。工艺参数的改变将使得结晶过程发生热力学和动力学控制的转换, 影响结晶产物的晶型晶貌。     

Pressure swing adsorption/membrane hybrid processes for hydrogen purification with a high recovery

Hydrogen was recovered and purified from coal gasification-produced syngas using two kinds of hybrid processes: a pressure swing adsorption (PSA)-membrane system (a PSA unit followed by a membrane separation unit) and a membrane-PSA system (a membrane separation unit followed by a PSA unit). The PSA operational parameters were adjusted to control the product purity and the membrane operational parameters were adjusted to control the hydrogen recovery so that both a pure hydrogen product (>99.9%) and a high recovery (>90%) were obtained simultaneously. The hybrid hydrogen purification processes were simulated using HYSYS and the processes were evaluated in terms of hydrogen product purity and hydrogen recovery. For comparison, a PSA process and a membrane separation process were also used individually for hydrogen purification. Neither process alone produced high purity hydrogen with a high recovery. The PSA-membrane hybrid process produced hydrogen that was 99.98% pure with a recovery of 91.71%, whereas the membrane-PSA hybrid process produced hydrogen that was 99.99% pure with a recovery of 91.71%. The PSA-membrane hybrid process achieved higher total H₂ recoveries than the membrane-PSA hybrid process under the same H₂ recovery of membrane separation unit. Meanwhile, the membrane-PSA hybrid process achieved a higher total H₂ recovery (97.06%) than PSA-membrane hybrid process (94.35%) at the same H₂ concentration of PSA feed gas (62.57%).

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Solid-State Photolysis of Azobis-3-Phenyl-3-Pentane. Crystal-Lattice Control of the Stereochemistry of Radical Disproportionation

The 3-phenyl-3-pentyl radicals from photolysis of azobis-3-phenyl-3-pentane (APP) in solution give 3,4-diethyl-3,4-diphenylhexane and a photolabile product assumed to arise by para coupling. Photolysis of APP as a crystalline solid at ?78° gives the disproportionation products 3-phenylpentane (PPH) and 3-phenyl-2-pentene (PP) as a 3:1 mixture of the E and Z isomers. This stereoisomeric ratio is surprising in terms of the solid-state molecular conformations, for which a topochemical scheme predicts predominance of the Z isomer. Isotopic distributions in PPH, Z-PP and E-PP from photolysis of solid APP which was 82% deuterated in its methylene groups shows: (1) that Z-PP is formed under strong lattice control; (2) that E-PP is formed in a process with greater, but not complete, molecular freedom; and (3) that there is often a dynamic competition for hydrogen-atom donation between the two radicals involved in disproportionation.     

冷凝分离法轻烃回收工艺影响C_3~+收率因素系统分析

一定组成的原料气,利用冷凝分离法进行轻烃回收时,对影响其C3+收率的因素进行了较为全面系统的分析,具体包括:冷凝、分离、工艺技术、工艺系统参数控制、设备效率等。同时,还设计了一种能提高C3+收率的三级分离工艺流程。     

Design and control of extractive distillation for the separation of methyl acetate-methanol-water

The azeotrope of methyl acetate methanol and water was isolated using extractive distillation with water as entrainer. The pressure-swing extractive distillation (PSED) process and vapor side-stream distillation column (VSDC) with the rectifier process were designed to separate the methyl acetate, methanol and water mixture. It was revealed that the VSDC with the rectifier process had a reduction in energy consumption than the PSED process. Four control schemes of the two process were investigated: Double temperature control scheme (CS1), Q_R/F feedforward control of reboiler duty scheme for PESD (CS2), Q_R/F feedback control scheme for VSDC (CS3), the feedback control scheme of sensitive plate temperature of side-drawing distillation column to dominate the compressor shaft speed (CS4). Feed flow and composition disturbance were used to evaluate the dynamic performance. As a result, CS4 is a preferable choice for separation of methyl acetate-methanol-water mixture. A control scheme combining the operating parameters of dynamic equipment with the control indicators of static equipment was proposed in this paper. It means using the sensitive plate temperature of side-drawing column to control the compressor shaft speed. This is a new control scheme for extractive distillation.     

Drying powdered coal with the aid of ultrasound

The results of introducing ultrasound into three different drying processes has been discussed. The processes included: (1) static drying of a layer of powdered coal with airborne ultrasound, (2) rotary kiln drying with airborne ultrasound, and (3) drying of powdered coal on a sloping, ultrasonically vibrated metal trough. In all three processes, the introduction of ultrasound increased the drying rate.

The frequency of ultrasound used was 20 kHz with sound intensities up to 165 dB. The pulverized coal used had a size range from 400 μm to less than 2 smm, with 65% being less than 150 μm in size. Air temperatures used varied from 65 to 300 °C.

The most energy-efficient drying process with ultrasound was found to be the sloping, ultrasonically vibrated trough. However, this process was limited to the use of an initial coal powder feed containing less than 10% moisture. For moisture contents above 10%, a dual drying system could be used. For example, the rotary kiln drier could be used ahead of the trough drier.

Both the static airborne ultrasound drying process and the ultrasonically vibrated trough drying process work best with a relatively thin layer of powdered coal. However, the residence time for the powdered coal being dried is measured in seconds for the sloping trough process in contrast to minutes for the static drying process. The static drying of a layer of powdered coal is also a batch-drying process while the rotary kiln and sloping trough are continuous processes. The advantages of the static airborne ultrasonic drying process would be: (1) closer control of the drying process, and (2) smaller quantities of powder can be used.     

A new process for Al2O3 production from low‐grade diasporic bauxite based on reactive silica dissolution and stabilization in NaOH‐NaAl(OH)4 media

A new process of Al₂O₃ production from low‐grade diasporic bauxite based on the reactive silica dissolution and stabilization in concentrated NaOH‐NaAl(OH)₄ solutions is proposed and proved feasible. NaOH and Al₂O₃ concentrations and leaching temperature were found to be the main factors affecting the leaching process of reactive silica. The A/S (mass ratio of Al₂O₃/SiO₂) of diasporic bauxite was enhanced from 5.4 to 15 by reactive silica removal under the optimum operation conditions. Two obvious steps control the whole leaching process of reactive silica in NaOH‐NaAl(OH)₄ media: reactive silica dissolution and desilication products (DSPs) precipitation. The kinetics data of two controlling steps fit a shrinking core model based on the calculation of OH^? activity with the aid of OLI platform and an empirical kinetic model well, respectively. Apparent activation energies of reactive silica leaching in the temperature range from 80 to 110 °C are 101.91 and 58.65 kJ mol^?1 for the two steps, respectively. The stabilization mechanism of reactive silica in concentrated NaOH‐NaAl(OH)₄ solution was also elucidated based on the complexation of aluminum‐bearing species and the calculation of supersaturation to DSP. It was found that the concentration of OH^? sharply decreases due to the formation of Al(OH) species with increasing aluminum concentration, suppressing greatly DSP precipitation. This proposed process paves the way for Al₂O₃ production from low‐grade diasporic bauxite with high‐reactive silica content. © 2011 American Institute of Chemical Engineers AIChE J, 2012