Residence-time distributions at high recycle ratios: Limiting forms obtained by increasing the recycle and by reducing the throughput

The residence-time density function for a recycle system tends to a limit as greater recycle ratios are considered for a fixed flow rate through the sy to a limit as smaller flow rates through the system are considered for a fixed recycle flow.If there is no part of the system through which the rate of transport is bounded when the recycle rate is increased for a constant net flow, the limiti of the system volume to the volumetric rate of flow through the system. When the rate of transport is bounded in some zone of the system, the limiting has an anomalous mean if transport ceases in a region of the system.Comparable rules can be advanced for the limiting distribution of normalized residence times when the net flow through the system is reduced at a const rates within the zones of the system and the net rate of transport through the system as the limit is taken. The presence of dead volume at this limitExamples are given of the several types of limit for systems where the rate of transport is limited by a flow-rate restriction in part of the system, a     

Evaluation of the types of emission systems observed in aqueous media with controlled-release formulations

Three types of release systems have been observed for controlled release formulations (CRF) of biocides in aqueous media. A type I system, which is concentration dependent, can be divided into a IA system whose concentration maximum is dependent upon sample size and degradation, and a IB system whose concentration is dependent upon the solubility of the biocide in the solvent. A type II system, which is time dependent, can be divided into a IIA system whose release rate is dependent upon t^1/2 and a IIB system whose emission is zero order or dependent only upon time. A type III system, which is a failure system, can be divided into a IIIA system whose concentration decreases to a nondetectable range as a function of t^1/2 and a IIIB system whose decreasing concentration is first order. Equations relating the theoretical life of the CRF to its bioactive life are also presented.     

RFID系统在小料配料产品中的应用

RFID系统作为新兴的系统识别解决方案,它开始在橡胶配料产品中替代原有的条码识别系统。本文详细介绍了SICK公司RFID系统在某小料配料项目中的应用。     

On-line process fault detection and diagnosis in plants with recycle

A process fault detection and diagnosis system is performed for the complex case of plant-wide control in processes with recycle in which the control system is the inventory control. It is considered an artificial neural network based supplement of a fuzzy system in a block oriented configuration. A methodology to design the system is described. As a case study, a chemical plant with a recycle stream is considered. Faults in supply of raw materials and in controllers are simulated. Performance of the system to handle simultaneous faults is also analysed. A comparison is made against a classification method (artificial neural networks) and an inference method (knowledge — based system).     

Electrocapillary elements. V. Acceleration meters working in short-circuit output conditions

The idea of a system for measuring the acceleration of an alternating movement is presented. The system comprises an electrocapillary transducer and an electronic system consisting of a current-voltage converter and an integrating system. The transducer output is in a short-circuit state because it is connected to the current-voltage converter. The system presented can also be applied to construction of an alternating pressure amplitude meter.     

Control of a Hybrid Energy Storage System for a Hybrid Compensation System

The combination of two or more different energy storage technologies in a hybrid energy storage system appears to be advantageous if the combination of technologies fulfils the storage purpose better than a single storage technology. Herein, requirements regarding the performance of the storage system are determined for a hybrid compensation system for provision of system services in medium‐voltage grids. In hybrid storage systems, a common control system ensures that the present storage technologies are utilized in such a way that total storage efficiency is highest and that usability of the application is maximized. The control system of a hybrid storage system consisting of a redox flow battery and high‐speed flywheel storage is introduced and evaluated.     

基于DRNN神经网络的石油钻机自动送钻系统智能控制研究

针对钻井过程的非线性、不确定性和实时性要求,采用基于对角神经网络(DRNN)的控制方案,能在线自适应的调整P ID控制器的3项参数。以自动送钻实验系统模型为被控系统进行仿真实验,仿真结果表明可以达到较为理想的控制结果,基于DRNN神经网络控制器结构简单,易于实现,效果明显优于传统的P ID控制器。     

Automation of Pneumatic Transport of Glass Batch Components

The operation of a pneumatic transport system for material components of a glass batch is analyzed. A system for automatic control of the executive mechanisms of the system based on a TA-23B pneumatic barrel pump is implemented using a microprocessor system and a control panel.     

The Number of Normal Components of Essentially Disconnected Coronoid Systems

An essentially disconnected coronoid system is defined as a coronoid system with some Kekulé structures and fixed bonds. The number of Kekulé structures (or perfect matchings) of a coronoid system G is the product of the number of perfect matchings of each normal component in G. In this article, it is proved that the boundary polygon of a normal component without any vertex lying on the boundary of an essentially disconnected coronoid system is a hexagon. Consequently, a lower bound on the number of normal components of an essentially disconnected coronoid system is obtained.     

会计电算化的发展趋势

会计电算化以现代工具电子计算机处理会计系统.应用会计核算和财务管理,建立整个会计信息网络平台,提高财会管理水平和经济效益,使我国会计电算化工作从核算系统向管理信息系统发展.     

怎样设计可靠的在线分析仪表取样系统

在线分析仪表能否可靠运行，大部分情况取决于取样系统是否完善。什么样的取样系统才算是一个好的系统，怎样才能设计一个好的取样系统，是用户和设计人员都想知道的一个问题。本文在这方面进行了很好的探索与总结。     

MVR并联双效蒸发结晶系统设计及研究

利用蒸发法处理工业废水,能够实现废水的资源化利用。本文针对不同类型蒸发器适用范围受限问题,将降膜式蒸发器与强制循环蒸发器联用,提出了机械蒸汽再压缩（MVR）并联双效蒸发结晶系统。首先设计了系统的工艺循环流程并建立数学模型,对该系统及其设备进行质量和能量衡算,并对模型的可行性进行核算。随后建立系统性能的?分析模型,对常压下质量分数为5%的硫酸钠溶液蒸发结晶进行实例计算,并将其与传统三效蒸发结晶系统进行比较。通过综合能量分析与?分析,MVR并联双效蒸发结晶系统的节能程度更大,其效能系数（COP）值为21.4,相同工况下高于传统三效蒸发结晶系统82.2%,而单位能耗仅为传统三效蒸发结晶系统的17.6%;其?效率高于传统三效蒸发结晶系统51.5%,?损失则低于传统三效蒸发结晶系统24.7%,这表明MVR并联双效蒸发结晶系统热力学完善程度更高,在节能方面有较大的推广应用潜力。     

复杂系统故障诊断中一种多黑板问题求解模型的实现

针对化工过程故障诊断问题的复杂性,在催化裂化故障诊断专家系统开发工具的设计过程中,提出一种多黑板问题求解模型。对系统中知识体的描述进行分析,给出基于该模型的系统结构,对系统的具体实现进行讨论,并对其调度算法进行研究。结果证明,该体系结构是专家系统在解决各种复杂问题时的一种良好的问题求解途径。     

一种新型太阳能溶液预处理电渗析再生系统

太阳能溶液除湿空调系统是一种具有较大节能潜力的新型空调系统。然而,太阳能热再生系统严重依赖于环境工况,在高温或高湿的气候条件下其再生后得到的除湿溶液将不能满足除湿的需求。提出一种用于溶液除湿空调系统的新型太阳能溶液预处理电渗析再生系统,分析了该系统的工作原理,建立了该系统的耗能模型,并与传统太阳能热再生系统进行了对比研究。研究结果表明,太阳能溶液预处理电渗析再生系统具有较高的节能潜力。     

Double-command fuzzy control of a nonlinear CSTR

In this research, double-command control of a nonlinear chemical system is addressed. The system is a stirred tank reactor; two flows of liquid with different concentrations enter the system through two valves and another flow exits the tank with a concentration between the two input concentrations. Fuzzy logic was employed to design a model-free double-command controller for this system in the simulation environment. In order to avoid output chattering and frequent change of control command (leading to frequent closing-opening of control valves, in practice) a damper rule is added to the fuzzy control system. A feedforward (steady state) control law is also derived from the nonlinear mathematical model of the system to be added to feedback (fuzzy) controller generating transient control command. The hybrid control system leads to a very smooth change of control input, which suits real applications. The proposed control system offers much lower error integral, control command change and processing time in comparison with neuro-predictive controllers.     

Monitoring and handling of actuator faults in two-tier control systems for nonlinear processes

This work focuses on the monitoring and reconfiguration of two-tier control systems applied to general nonlinear processes in the presence of control actuator faults. Specifically, a general class of nonlinear process systems is first considered and is controlled by a two-tier control system integrating a local control system using continuous sensing/actuation with a networked control system using asynchronous sensing/actuation. To deal with control actuator faults that may occur in the closed-loop system and eliminate the ability of the two-tier control system to stabilize the process, a fault detection and isolation (FDI) and fault-tolerant control (FTC) system is designed which detects and isolates actuator faults and determines how to reconfigure the two-tier control system to handle the actuator faults and ensure closed-loop stability. The FDI/FTC system uses continuous measurements of process variables like temperature and asynchronous measurements of variables like species concentrations. We develop reconfiguration-based FTC schemes that effectively deal with faults in the actuators of both the local and networked control systems. A detailed mathematical analysis is carried out to determine precise conditions for the stabilizability of the FDI/FTC system. The method is demonstrated using a reactor-separator process consisting of two continuously stirred tank reactors and a flash tank separator with recycle stream.     

CO2跨临界热泵系统采暖工况下能效和经济对比分析

为提高CO₂跨临界热泵采暖系统的性能,提出了双级压缩双气冷器中间补气回热系统。结合其他3种CO₂热泵系统和R134a单级压缩回热系统,通过建立热力学模型,分析各因素对系统能效的影响。此外,通过构建综合考虑初始投资成本和年运行成本的经济性评价模型,结合典型年气象参数,研究不同城市中各系统在运行周期内的总投资情况。结果表明,CO₂热泵系统中,双级压缩双气冷器中间补气回热系统最优COP_h最高且可以超过R134a单级压缩回热系统,在环境温度为0℃、出水/回水温度为65℃/40℃时,理论性能系数（COP_h）可达2.58,比R134a系统高9.1%,比CO₂单级压缩系统高22.5%,且排气温度不超过现有压缩机排气温度极限,是能效最优系统。在选定样本城市中,热泵系统运行周期内的总投资成本在上海最低,而在沈阳最高,可见总投资成本受气候区域影响较大。由于CO₂压缩机成本过高,CO₂热泵系统的总投资成本高于R134a系统。随着CO₂热泵技术的提高和生产规模的扩大,当压缩机成本降低80%,CO₂双级压缩双气冷器中间补气回热系统的总投资成本将低于R134a系统。     

Performance of new liquid redox desulfurization system of heteropoly compound in comparison with that of iron chelate

In order to achieve a comprehensive understanding of the performance of the heteropoly compound (HPC) absorbent systems for H₂S removal developed before this study, a comparable study was made concerning the desulfurization characteristics, sulfur loading capacity (SLC) and desulfurization product composition, taking Fe-EDTA system as a standard. The desulfurization effect of HPC multicomponent absorbent system can be greater than that of Fe-EDTA system during long time of operation; the regeneration effects of HPC and Fe-EDTA system are similar. The SLC of single HPC is almost the same as that of the Fe-EDTA system, and the multicomponent system of HPC has SLC which is 12.93% higher. Furthermore, the desulfurization product from HPC system contains sulfur mainly, which is superior to that from Fe-EDTA system. Hence, HPC absorbent system developed would be of promising application value.     

利用LNG冷能与工业余热的有机朗肯循环复合系统优化分析

对中低温余热（150℃）及LNG（-162℃）冷能联合利用,设计了一种复合式有机朗肯循环,对此复合循环系统进行了详细的热力分析及经济性分析,并与相对应的单独循环系统进行了比较。结果表明,该复合循环系统的净输出功比单独循环系统提高了41.55%,热效率和 效率也分别提高了18.09%和19%,单位功率所需换热面积也仅为单独循环系统的61.03%。对该复合循环系统各部件进行了可用能损失分析,同时考虑了LNG余压的利用,进一步提出了优化方案。