PLC distributed control of cement production line
simatic PCS7 is a new generation control system of Siemens. It is based on the previous SIMATIC products. The company has international advanced production equipment experience. It has a modular structure, which can be configured according to the system, from a single small automation solution to a complex control system
this project is a 1000 ton clinker cement production line with a daily output of 1000 tons, which is equipped with a central control room (CCR). Its control, monitoring and management scope includes raw material batching, raw material grinding, waste gas treatment, raw material entering the kiln, preheater, rotary kiln, cooler, clinker storage, medium powder preparation, water sludge batching, cement grinding and other main production processes. Monitor, manage and operate the current situation and trend of the production process in the central control room, so as to achieve the purpose of stable and reliable operation of the production process equipment. According to the production process, there are four on-site control stations, i.e. 1 #, 2 #, 3 #, 4 #, which are respectively set in the raw material mill electrical room, kiln tail electrical room, kiln head electrical room and cement mill electrical room. Their respective control and detection are: 1 * field control station: raw material batching station, raw material grinding and waste gas treatment. 2 # field control station: raw material entering the kiln, firing kiln tail and firing kiln. 3. Field control station: firing kiln head, pulverized coal preparation and transportation. 4. On site control station: clinker batching, cement grinding and transportation. The on-site control station has the functions of closed-loop control, motor sequence interlocking control, data acquisition, data processing, storage, alarm, etc; With all the functions of digital and analog quantity control, it can effectively control the production process, implement logical interlocking, sequence control, group start/stop of the motors in the production process together with the electric motor control center (MCC), and transmit process data and information with the operation station in the central control room through the data high-speed channel, receive various control commands from the operators, and complete the detection and control requirements. In addition, it also has/offline configuration function, self diagnosis and other functions. The field control stations of the distributed control system can complete their own control tasks independently
in the bidding activity of this project, the number of vehicles disassembled by our company soared to about 100 every day. They chose SIMATIC PCS7 of Siemens company. According to the requirements of the bidding document and the data provided: SIMATIC PCS7, the new distributed control system (DCS) of Siemens company, is the core part of fully integrated automation (TIA) and an innovative product that uses a single, fully integrated and universal system to solve automation problems. According to the introduction of technical data, within the scope of the new automation concept, SIMATIC PCS7 has overcome many obstacles between systems: obstacles between the computer field and dcs/plc, obstacles between control and monitoring, obstacles between centralized and distributed automation structures, and obstacles between manufacturing and technological processes. It has all the advantages of a truly flexible and integrated system. At present, 341 sets of PCS7 systems have been sold worldwide and 12 sets are running in China. It is the first time in China that all components of PCS7 are used in this project to form a complete factory full automation
the distributed field control unit (as) is S7400 master station plus et200m distributed i/o. Siemens' newly developed high-performance PLC has the following characteristics: high speed, ruggedness, strong communication ability, easy to use, and can meet user requirements. In short: high performance, simple operation. Including communication, processing speed, diagnosis and perfect processing functions. The central processor selected by the automation system from the SIMATIC S7400 system is combined in a modular form, such as based on the following SIMATIC CPUs: s7414 - 2dp, s7416 - 2dp, s7417 - 4dp, and the system composition: power module, CPU, communication processor. Distributed i/o adopts distributed et200m station equipped with s7300 module for process connection. The distributed field station et200m is a modular i/o station where the diaphragm touches a variety of new materials such as inorganic materials, inorganic fiber materials, organic high molecular material fibers, etc. and is used for high centralized input/output equipment. It has the ability to deal with all distributed automation problems and add gaskets between the oil collector and the pump body. It can be extended through s7300i/o module. It is used to replace S7400 module and greatly reduce the cost. Et200 is a passive slave of PROFIBUS - DP, with a maximum transmission rate of 12mbit/s. Et200m i/o station includes im153 interface module and up to 8 s7300 programmable controller modules, which are connected with the automation system through PROFIBUS DP fieldbus. For this scheme that requires high reliability, it is required to be able to plug and unplug modules during operation, so a kind of plug and take out i/o subsystem is applied, which allows hot plug and unplug modules without stopping the operation of the system. Technical information: "the active bus module makes it possible to hot replace the module during operation. There is no need to interrupt the operation when replacing the module, the old module still keeps running, and the new module can start automatically when inserted."
using et200m i/o can form a completely decentralized automation system. Siemens' PROFIBUS field bus is a field bus standard that is widely used and rapidly developed in contemporary times. Compared with the peer-to-peer connection used in the past, the advantages of fieldbus are now widely known. The rapid popularization of PROFIBUS shows that fieldbus has been accepted by people. Et200m i/o is a distributed automation system based on PROFIBUS. Therefore, SIMATIC PCS7 supports the development of i/o in a more decentralized direction. All PCS7 automation systems have a PROFIBUS - DP interface integrated on the CPU. Moreover, intelligent i/o devices can be directly connected to PROFIBUS - DP. Compared with current fieldbus technologies, PROFIBUS still has some shortcomings. PROFIBUS is a master-slave structure. Its configuration needs to be transmitted from the master station to each slave station, and then wait for all slave stations to send back ready signals, which takes up most of the time in each initialization of the master station. When the master station operates normally, the failure of any slave station will lead to the shutdown of the master station. This makes us feel that it is really a major defect of PROFIBUS. In addition, et200m has a prominent advantage, that is, S7 - 300 analog module. An analog module can cover all measurement ranges. Up to 40 different measurement ranges can be set separately through the software. If necessary, the measurement range of each channel can be different. Mixed mode is also OK. These greatly increase flexibility. During the training and on-site commissioning, we repeatedly emphasized this point to the user. Now the user has benefited from it and can master the configuration method. Moreover, et200m also reduces the cost of logistics and inventory, because for all measurement ranges, only one module is needed for inventory backup. In addition to et200m distributed i/o module, the field equipment in this project also includes SIPOS execution
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