Reconstruction and expansion of the hottest sewage

2022-08-06
  • Detail

Sewage treatment reconstruction and expansion project

I. system overview

the control level of the automatic control system of the project is set to three levels:

field manual control on the first floor

field manual control boxes are set at each electrical station, which can start and stop each test equipment and each actuator separately

the second layer of PLC logic linkage control

PLC automatically controls the operation status of electrical equipment in each station according to the data collected by each test equipment on site and the system equipment operation logic relationship

the third layer central control

computer monitoring, modifying PLC control parameters, and the upper computer inching control to achieve real-time monitoring

manual control and automatic control can be switched through the "manual automatic transfer switch" in the machine room or central control room respectively. This control mode can ensure the safe operation of the sewage treatment plant to the greatest extent

the central control computer can monitor and control the sewage treatment process of the whole system in real time, track and receive the data signals of PLC at any time, patrol test various types of analog quantities, and alarm various types of faults or non-standard alarms

it has the ability to analyze and process real-time data and historical data, conduct dynamic simulation, trend analysis, tabulation and printing, and draw curves for the main process flow; Keep the main data permanently. It also displays the visual dynamic color picture of the whole process flow or local links on the CRT, and dynamically displays the operation status of the main components of the process flow through the embedded large screen

with the help of lines and modem cards, remote monitoring can be realized to monitor the operation status of the whole system, so as to quickly solve problems and eliminate faults

II. Hardware system configuration

fieldbus technology

the system adopts the most advanced Fieldbus Technology (PROFIBUS), which can directly form a network through the public bus for all distributed automation equipment on the site, including automatic intelligent instruments, sensors, actuators and transmitters. Its biggest advantage is:

1. Although there are hundreds of instruments, sensors and actuators on site, it only needs to lay a communication cable to transmit all the measured point data to the destination. This greatly reduces the wiring workload, reduces the cable cost, and facilitates installation and maintenance

2. It has higher reliability and transparency in process control and faster data exchange speed. Even if the distance is as far as several kilometers, all information can be transmitted to the destination in milliseconds

3. After the implementation of open fieldbus, all automation equipment (PLC, PC, man-machine interface system, sensor and actuator) in the system can exchange data and communicate through a unified bus

4. Superior connectivity and expansion performance: the enterprise management layer, sewage treatment control layer and field automation equipment layer can be seamlessly integrated into a network system through SIMATIC network. In the future, if field measuring points or control points need to be added, they can be directly connected to the bus without changing the original system structure and wiring framework

introduction to monitoring contents

according to the list of control instruments provided by the user:

· 8 sets of ultrasonic liquid level meters (Prosonic fdu81)

· one ammonia nitrogen instrument (phox625/100/01)

· 1 set of ammonia nitrogen instrument filtration device (phox)

· 2 sets of electromagnetic flow meters (ifm4100 DN250)

· 4 dissolved oxygen meters (cyh101-d)

· three flow meters (lzb-50)

· 3 ph/t meters (cpm152)

· 2 sets of electromagnetic flow meters (ifm4100 DN25)

· 2 sets of electromagnetic flow meters (ifm4100 DN32)

the quantity of the above instruments can roughly determine that the input analog quantity is about 21 points, the input and output switching values are about 32 points respectively, and the output analog quantity is about 21 points

real time process control

contents include:

phosphorus salt dosage control according to the input of electromagnetic flowmeter, the output module of PLC controls the phosphorus nutrient salt dosage of the regulating tank (controls the quantitative dosing pump), forming a closed-loop control

ph value control: PLC controls the dosage of soda ash according to the input measured by pH meter, forming a closed-loop control

methanol dosing control according to the input of electromagnetic flowmeter, the output module of PLC controls the methanol dosing of anoxic tank (controls the quantitative dosing pump), forming a closed-loop control

control of dosing amount of soda ash according to the input amount of electromagnetic flowmeter, PL continues to develop and innovate the output module of C to control the dosing amount of soda ash in the oxidation tank (control the quantitative dosing pump), forming a closed-loop control

the concentration of influent ammonia nitrogen is controlled by PLC according to the input amount of ammonia nitrogen instrument, which forms a closed-loop control

the preparation and utilization of chemicals for integrated circuits and discrete devices, chemicals for printed circuit board production and assembly, chemicals for display devices, chemicals for color liquid crystal displays, chemicals for printed circuit board (PCB) processing, ultra clean and high-purity reagents and special (Electronic) gases, advanced packaging materials and chemicals for grinding and polishing, etc. the dissolved oxygen in the oxygen pool is controlled by PLC according to the input of the oxygen flowmeter, Control the oxygen supply of the oxygen supply pump

the inlet water temperature is controlled by the PLC to measure the probe input according to the water temperature

sludge pump start/stop control the start/stop switch of sludge pump is controlled by PLC output

the dosing pump still tends to rise after the temperature reaches the fixed value of 1. The PLC controls the start and stop time of the water pump according to the input of the ultrasonic liquid level gauge

secondary sedimentation tank sludge discharge program control

main equipment operation parameter monitoring

audible and visual alarm

can display the alarm information of the latest alarm point in real time, accompanied by audible and visual alarm. After pressing the alarm elimination button, the alarm sound can be eliminated. It is arranged in time sequence and automatically recorded in the alarm database of the computer

the alarm level can be divided into three levels: general alarm; Serious alarm; Fatal fault

in case of general alarm, only a warning will be given for reference through a household battery, and the equipment will still proceed according to the established procedure

in case of serious alarm, except for the alarm, this part of the equipment will be automatically switched to the standby equipment, and the rest of the equipment will still be carried out according to the established procedure

in case of fatal fault, the system will automatically switch to manual state in addition to alarm

III. software system preparation

operating system software package (InTouch 5.6 configuration software and dynamic link library)

1. InTouch 5.6 configuration software

intouch design supports the establishment of independent and distributed applications. Independent application means that each monitored system only uses one operator interface (OI), such as sewage treatment control. Independent application is usually easier to configure, small to no network, and requires simple maintenance. Distributed applications are much more complex and often have several layers of networks. Typical distributed applications have a central control room computer, centralized data storage, and a cluster of

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