The hottest PLC scheme is in Zhangjiagang conch 42

Application of PLC scheme in Zhangjiagang conch Φ 4.2x11m cement grinding system with roller press

project introduction

Anhui conch group is a large state-owned enterprise group established in 1997 and the largest building materials production enterprise group in China at present. Zhangjiagang Conch Cement Co., Ltd. is a cement grinding enterprise established by Anhui Conch Cement Co., Ltd. in September, 1998. The project started construction in April, 2001, and there are two sets Φ 4.2x11m belt roller press, batching silo, cement silo and 10000 ton wharf were constructed synchronously, and were completed and put into operation in April 2002

introduction to control system

1) system control range

raw material warehousing and transportation - cement grinding (lines I and II) - cement outbound and packaging system

· raw material storage and transportation process flow:

gypsum crushing and transportation → slag warehousing → limestone warehousing → clinker transportation warehousing → raw materials into the dust collector of the grinding head bin → raw materials into the grinding head bin → clinker into the grinding head

bin → gypsum into the grinding head bin → limestone into the grinding head bin → slag into the grinding head bin

· cement mill process flow:

grinding thin oil station → cement warehousing → cement mill → cement mill control → grinding roller press → material feeding Cement mill/roller press → fly ash into cement mill

· cement delivery and packaging process flow:

dust collection on the top of the silo → fan control of the chute on the top of the cement silo → cement storage

2) automatic control circuit

· grinding 1 middle and grinding 1 tail

· cement silo weight control system

· grinding 1 tail negative pressure control system

· fly ash silo solid flowmeter control system

3) collapse or wear of the wedge-shaped inclined plane sequence control downtime

in order to ensure equipment safety and no-load startup, it is necessary to plan the equipment downtime

· raw material allocation and transportation

· cement grinding

· limestone and auxiliary raw materials enter the batching silo

· cement storage and transportation

4) introduction and configuration of cement grinding control system

the monitoring software of the system is Siemens WinCC 5.0, and the control system selects SIMATIC s controller and et200m i/o

of Siemens in Germany for signal acquisition and processing. The specific configuration is as follows:

· auxiliary raw materials and cement grinding second-line part

configure a SIMATIC s controller with 12 et200m remote stations to control all analog quantities and digital quantities of cement grinding second-line and raw material batching part. Among them, a roller press system of cement grinding line 2 communicates with SIMATIC s control station through PROFIBUS-DP. Configure a WinCC operation station as the configuration programming and operation of raw material batching and cement grinding

· a SIMATIC s control station with 8 et200m remote stations is configured for the cement grinding line and the cement silo top to control all analog and digital quantities of the cement grinding line and the cement storage (silo top). Among them, a roller press system in the cement grinding line communicates with SIMATIC s control station through profibusdp

. Share a WinCC operation station with the second-line cement grinding part as the configuration programming and operation of cement grinding and cement storage (warehouse top)

· a SIMATIC s control station with 18 et200m remote stations is configured at the bottom of the cement silo and the package and bulk part to control all analog and digital quantities at the bottom of the cement silo and the package and bulk part. The packaging part is operated by touch screen tp27. The control system can realize dynamic flow chart, trend chart, alarm display, report recording and process dynamic operation control

· UPS power supply is used as the power supply of the system, which can prevent ultra-high voltage, undervoltage, surge, peak pulse interference, power failure interference and even lightning attack from the large LCD screen

anti interference measures of the control system

the automatic control system of Zhangjiagang conch has many weak current equipment, and the number of various control cables and signal cables is very large, so the system is very vulnerable to various interferences. If measures are not taken to eliminate the interference, the normal operation of the system will be seriously affected. Therefore, the automatic control system adopts the following anti-interference measures:

· all digital input/output modules and analog input/output modules of the system field control station adopt photoelectric isolation to isolate various on-site signals from the system backplane bus

· all digital output signals of the system field control station are isolated by relays to realize the isolation between each digital output channel and eliminate the mutual interference between digital output signals

· analog isolators are used for all analog input/output signals of the system field control station to realize the isolation between each analog channel and eliminate the mutual interference between analog signals

· all analog input/output signal cables that are easy to operate in the system field control station adopt shielded cables, and the shielding layer is grounded at one point on the side of the control cabinet, eliminating space interference

· the control cable, signal cable and system power cable of the system field control station shall be wired separately to maintain a certain distance. In particular, the power cable of high-power frequency converter can produce strong spatial high-frequency interference, so the metal pipe should be used for threading, and the metal pipe should be well grounded

conclusion

Zhangjiagang conch has been in good operation since it was completed and put into operation in April 2002. The system can reliably and accurately complete the control operation, monitor and record the operation status of the cement production process in real time, and respond to various emergencies on site in a timely manner, and has achieved good results

application experience

with the continuous innovation and improvement of Siemens PLC technology, users will be the direct beneficiaries. In terms of technical development, PLC is also constantly challenged by other control systems based on computer technology, by the urgent need to update and develop the software of PLC technology itself, by a new industrial control structure, not only the decentralized control, but also the decentralized network, and by the open modular architecture control system (OMAC). Therefore, PLC will inevitably develop in the direction of improving its software and hardware