水污染监测英文文献

兰州交通大学毕业设计 外文文献 1 The Besign of Oxidation Ditch Control System Based on PLC and Kingview Jie SU College of Mechanical Engineering Ningxia University Yinchuan China Su5989703jie Xuejun Zhu College of Mechanical Engineering Ningxia University Yinchuan China zhuxuejunnxu Abstract With the exhaustion of water resources the urban sewage circulation processing has become an indispensable way for the construction of an environmental friendly energy saving and sustainable society The key is directly determined by the superiority of treatment process and automatic level of control system For instance there is a sewage treatment plant in Yinchuan city which has the sewage treatment capacity of 50 000 t d and uses the oxidation ditch process In this paper we design an automatic control and monitoring system for the sewage treatment plant In the system Siemens S7 300 PLC is a slave station It can be used to control field devices and collect variable data from sensors including DO PH liquid level flow and MLSS etc The upper computer uses KingVIEW software to exchange data with slave station thereby realizing the centralized management Keywords Sewage treatment oxidation ditch process PLC DCS KingVIEW I INTRODUCTION Water is a basis for the survival of human being and is the foundation of all creatures It plays an important role in regulating global climate But with the rapid economic and social development and the further promotion of industrialization and urbanization water resources have become an important factor of restricting economic development 1 By the end of 2010 Chinese urban waste water quantity is 133 45 million m3 per day but urban sewage disposal capacity is only 102 62 million m3 d The rate of urban sewage treatment is only 76 9 The general situation of water resources is worsening and improving the capacity of sewage treatment is extremely urgent 兰州交通大学毕业设计 外文文献 2 In the sewage treatment process oxidation ditch is the core of biological chemical method and influences the quality of effluent water directly Using the PLC controller with a superior performance a stable and reliable integrated automation system for sewage treatment can be designed and has great significance The configuration monitoring system can help the sewage treatment process to realize fully automatic control KingVIEW with industry is leading HMI and object oriented environment with strong graphic network function can exchange data realtime with the machine and other computer application 2 Through the communication protocol conversion interface I O Server it is convenient to connect other industrial control equipment Due to KingVIEW we can create the oxidation ditch process section efficiently by using computer interface II INTRODUCTION TO THE OXIDATION DITCH PROCESS At present biological chemical method is a way most frequently used in urban sewage treatment Compared with chemical treatment biological treatment method for the sewage processing is more economical efficient and mature It is to absorb and transform the harmful substances in sewage water by the metabolism of microorganism The oxidation ditch process is typical in biological treatment method It is a kind of connections between the front and the cycle flow aeration ditch It can also be called continuous circulating aeration which is a kind of activated sludge variant 3 Considering the stability of sewage water and its treatment capacity between 30000 to 100000 m3 per day we choose the Carrousel 3000 oxidation ditch It can fully embody the good treatment effect and its energy saving characteristic of oxidation ditch process 4 5 It has a thick grid sewage pump room ascension grid aeration heavy fine sand pool choose pool anaerobic pool oxidation ditch eventually pond contact disinfection pool backflow sludge pump room the sludge regulation ponds and sludge dewatering etc The Carrousel 3000 oxidation ditch process section is shown in figure 1 and its flow diagram type in figure 2 After primary treatment urban sewage water flows into oxidation ditch with decomposition purification and finally gets to the stage of mud water processing The oxidation ditch process section is the place for biological treatment where waste water and the biological sludge are mixed table aeration machine provides suitable dissolved oxygen levels for bacteria metabolism help form alternately good oxygen lack of oxygen and anaerobic conditions in the trench and undertakes the main task of biochemical 兰州交通大学毕业设计 外文文献 3 treatment Figure 1 Carrouse 3000l oxidation ditch process section Figure 2 Carrousel 3000 oxidation ditch process flow Figure 3 DCS control system structure based on PLC and the KingVIEW III THE OVERALL DESIGN OF CONTROL SYSTEM As an object for control the demand for oxidation ditch process section mainly centers on data collection and its order and logic control Thus PLC is chosen as the slave station in 兰州交通大学毕业设计 外文文献 4 automatic control system 6 The system needs to realize monitoring and automatic control of the biochemical treatment process which mainly includes the control of table aeration machine propeller and water electric weir The DO value is monitored and by the use of soft measurement technology BOD is estimated and the flow of water is monitored based on the value of DO PH ORP Table aeration machine realizes its control by taking dissolved oxygen aeration as a control variable propeller adopts switch control water electric weir takes BOD as a variable to realize its control According to the characteristics of the Carrousel 3000 oxidation ditch process and its controlling requirements we can design a DCS control system in line with the idea of separate control and integrated management which is based on PLC and KingVIEW 7 As is shown in figure 3 the first level is Site layer mainly including inspection instruments the I O interface device and the local control cabinet The second layer is PLC programmable controller which can realize logic control based on the data collected from site and the logic relationship of equipment operation The third layer is the remote monitoring scheduling center mainly using industrial control computer IPC to monitor the real time parameters of process section and the working condition of equipments automatically adjust the equipment operation and realize the functions of alarming and interlocking It can also display the dynamic real time graph directly make the trend analysis and show and print the historical monitoring data 8 For the monitoring system we use Yanhua industrial computer IPC as the master station After installing the KingVIEW configuration software we can set up a database The SIMATIC S7 300 PLC is employed as a slave station In the oxidation ditch process period the logic control of table aeration machine propeller and water electric weir is realized based on the data collected from site and the logic relationship of equipment operation Touch screen will be fixed if needed mainly used to display the field of process parameters and configure control parameters which can realize the manual operation The central processing unit chooses CPU315 2 DP It has strong processing capacity and adopts modular design structure which has an easy configuration and is convenient for future expansion Equipped with CPU module CPU315 2 DP we need PS307 power supply module 1 piece CP343 1 comunication module 1 piece 2 pieces of 32 points SM321 DI module 2 pieces of 32 points DO module 1 piece of SM322 8 road SM331 AI module 9 SIMATICTP270 10 touch screen The data transmission is mainly achieved through adopting an universal open high speed and reliable 兰州交通大学毕业设计 外文文献 5 industrial Ethernet between master slave stand 10 By installing the distributed the I O ET200 it makes possible communication between the machine with the field under equipment and intelligent instrument constituting the bottom profibus DP Figure 4 figure 5 and figure 6 are the wiring diagram between PLC and the equipment instrument which are DI module DO module and the AI module of the wiring diagram respectively Figure 4 oxidation ditch process section digital input module wiring diagram 兰州交通大学毕业设计 外文文献 6 Figure 5 oxidation ditch process section digital output module wiring diagram Figure 6 oxidation ditch process section analog input module wiring diagram NOTE IFTAAMC Industrial frequency table aeration automatic machine conversion IFTAMMC Industrial frequency table aeration machine manual conversion IFTAMSR Industrial frequency table aeration machine soft running IFTAMMO Industrial frequency table aeration machine motor overloaded FCTAMAC Frequency conversion table aeration machine automatic conversion FCTAMSR Frequency conversion table aeration machine soft running FCTAMMC Frequency conversion table aeration machine manual conversion FCTAMMO Frequency conversion table aeration machine motor overloaded 1 PO 1 Propeller operation 1 PMO 1 Propeller motor overloaded 兰州交通大学毕业设计 外文文献 7 1 PCC 1 Propeller control conversion 2 PO 2 Propeller operation 2 PMO 2 Propeller motor overloaded 2 PCC 2 Propeller control conversion 3 PO 3 Propeller operation 3 PMO 3 Propeller motor overloaded 3 PCC 3 Propeller control conversion 4 PO 4 Propeller operation 4 PMO 4 Propeller motor overloaded 4 PCC 4 Propeller control conversion WEWL Water electric weir lower WEWC Water electric weir cap EWCC Electric weir control conversion EWMO Electric weir motor overloaded 1 PAC 1 Propeller automatic control 2 PAC 2 Propeller automatic control 3 PAC 3 Propeller automatic control 4 PAC 4 Propeller automatic control WEWR Water electric weir rise WEWD Water electric weir down IFTAMSAC Industrial frequency table aeration machine soft and automatic control 30HZFCTAMSAC 30HZ frequency conversion table aeration machine soft and automatic control ORP MI ORP Measuring instrument 40HZFCTAMSAC 40HZ frequency conversion table aeration machine soft and automatic control DO MI DO Measuring instrument 30HZFCTAMSAC 30HZ frequency conversion table aeration machine soft and automatic control PH MI PH Measuring instrument FMI Flow measuring instrument LMI Level measuring instrument MLSS MI MLSS Measuring instrument IV THE SOFTWARE DESIGN OF OXIDATION DITCH PROCESS SECTION PLC CONTROL STATION In the oxidation ditch process the control station is mainly responsible for data acquisition and monitoring of table aeration machine propeller water electric weir and apparatus In the oxidation ditch process we install two table aeration machines one of which adopts Frequency conversion control four propellers and a water electric weir All devices can realize local control remote control and automatic control We install DO meter PH meter and ORP meter whose data are sent to the PLC in the form of the 4 20 mA standard signal The oxidation ditch process is to absorb and decompose the matter in the sewage through the metabolism of microorganism Since the concentration of dissolved oxygen has 兰州交通大学毕业设计 外文文献 8 direct influence on biological activity it is of great importance to keep an appropriate dissolved oxygen level of the filter ditch According to previous experience when the dissolved oxygen level remains at 1 0 2 0 mg L the biological activity is the largest and the treatment effect is the best 11 DO meter transmits the dissolved oxygen to PLC in the form of standard electrical signal Based on DO value PLC adjusts the speed of the table aerator machine by regulating the frequency of inverter thereby controlling the concentration of dissolved oxygen in oxidation ditch 12 The DO control flow chart of Frequency conversion table aeration machine is shown in figure7 Figure 7 frequency conversion table aeration machine DO value control flow chart way Flow meter transmits the flow of water to PLC in the form of standard electrical signal and based on the flow data PLC controls the start stop of the propeller so as to keep the velocity above 0 3 m s V THE DESIGN AND REALIZATION OF KING VIEW MONITORING SYSTEM With the technology of soft measurement data measured by DO meter PH meter and ORP meter are sent to PLC in the form of standard electrical signal and then PLC will control the rise and fall of water electric weir based on the estimation of BOD5 After confirming the framework of control system and the scheme of hardware configuration in the stage of craft the human machine interface used to monitor the real time device status and parameters of Oxidation Ditch craft section is designed by the use of KingVIEW6 53 development 兰州交通大学毕业设计 外文文献 9 environment combined with the technology of database command language equipment and system configuration Its specific functions include oxidation ditch process interface operating parameters and settings real time and historical data query alarm operating authority etc Operators can not only learn the device operating parameters status alarms real time data display directly through interface but also can set up and operate parameters for the locale equipment VI CONCLUSIONS With this design of the control system it can make water index meet the demand of the second level of China s sewage discharge standard stably guarantee devices operate stably and reliably Meanwhile the system can be used easily and maintained conveniently It greatly reduce the workload and labor intensity of operators improve the utilization efficiency of energy and equipment solve the problem that equipments in the sewage treatment plant are distributed complex and difficult to control achieve energy conservation and reduce energy consumption as well which provides a theoretical reference for the design of urban sewage treatment system in the future Wastewater treatment process is a complex nonlinear uncertain and time varying process so the real time on line detection of water quality parameters has increasingly become a prominent problem The use of soft measurement technology for real time on line detection can be a good way to solve this problem 13 14 In order to overcome the errors caused by inaccurate model uses the advanced intelligent control system will become effective means PLC is a controller in the DCS it plays the role of Upload issued the FieldBus coexist and the locale equipments are supported different agreement to make the interchangeability poor The PLC communication module will be attached more and more importance by automation manufacturers 15 With the rapid development of network technology and enterprise s request for the interchangeability of locale equipment we must cater to the market Therefore in the future development of DCS Ethernet technology extension into the industrial control field device layer will become the trend 16 REFERENCES 1 Bin Chen Yuannong Li Yang ling vocational technology college J Journal of shallow city the rational use of water resources and management 2009 3 28 29 兰州交通大学毕业设计 外文文献 10 2 Yakun technology KingVIEW 6 53 3 Kaijun Wang Limin Jia Wastewater treatment new technology development and app