Microcomputer control system for sewage treatment

2022-08-17
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Microcomputer control system for oilfield sewage treatment I. Introduction when oil is pumped up from the ground, it needs to be dewatered and dewaxed in the combined station, and then sent to the refinery after a series of treatment, such as metering. Therefore, a lot of sewage in the combined station needs to be treated every day, so as to meet the discharge standard and avoid pollution to the surrounding farmland. The traditional treatment method is to use a filter tank, in which filter sand and other media are placed in layers, and the sewage is filtered from top to bottom. This method is not only inefficient and ineffective, but also very difficult to replace the media. In addition, at present, under the environment of market economy law, enterprises can treat sewage with high efficiency and quality, and reduce fines for non-standard discharge, which is of great importance to the economic benefits of enterprises. Therefore, we have developed a set of sewage treatment experimental device by using microcomputer control technology and membrane separation technology, which has improved the peace efficiency and management level for enterprises

second, the working principle of the system

the selection of the scheme of the sewage treatment system first depends on the safety of the membrane, because each ultrafiltration membrane module is a relatively closed cavity composed of 9000 hollow organic fiber thin membrane tubes, and each thin tube wall is distributed with many ultra-fine holes. When the sewage flows out of the thin pipe, under the action of a certain pressure, the purified water seeps out of the ultra-fine hole, the sewage continues to be recycled, and a part of the concentrated sewage is discharged. Therefore, it is necessary to ensure that there is a certain pressure up and down the module without overpressure. Without pressure, the purified water is difficult to penetrate

, and the overpressure module will be damaged. Therefore, strictly control the pressure: P1 0.25mp, P1-P2 =0.05mp, (p1+p2)/2-p3 =0.1mp. According to the process requirements of the system, it is also necessary to monitor and control several related flows, that is, q1:q2:q3=1:4:9, so that the circulating system can achieve material balance and maintain the normal operation of the system

sewage can only enter the module device after pretreatment such as cyclone desanding and turbidity limitation. Impurities will accumulate near the ultra-fine hole after the module works for a certain time, so it must be backwashed regularly. If the specified permeability is still not reached after a certain number of backwashing, chemical cleaning, namely acid pickling and alkali washing, should be carried out to ensure the normal operation of the system

III. hardware composition of the system

the ultrafiltration membrane sewage treatment device is composed of process equipment and microcomputer control system. The process equipment is 1.2m long produced by Dalian Institute of physics and chemistry, Chinese Academy of Sciences, ф= 15cm ultrafiltration membrane module group, stainless steel pipelines, tanks, pumps, valves, etc. The microcomputer control system is composed of an Advantech industrial computer, Adam series modules, operators and primary instruments

adam series is an intelligent device with built-in microcontroller and sensor to microcomputer interface. The module sends simple commands in ASC code format and communicates with RS-485 communication protocol. It has the functions of a/d, d/a, di/do, and communication

the ADAM module network of the control system adopts cascade mode, and is equipped with one adam4017, four adam4012, four adam4021, three adam4050, one adam4520, and one adam4510. The industrial computer mainly completes the setting and modification of process parameters, dynamic display of process flow, real-time control of flow and pressure, fault monitoring and alarm, storage, query and printing of key data, etc. Adam4017 and adam4012 mainly complete the data acquisition of flow, pressure, liquid level and turbidity, and send them to the industrial computer through RS485 bus. Adam4021 and adam4050 receive data from the microcomputer to control the operator, solenoid valve and pump respectively

the primary instruments on the field equipment are standard conventional instruments, whose output signal is standard Ma or v. adjust the temperature setting value Sv (red display) to the required setting temperature value to simulate the electrical signal. The analog signal is converted and filtered by ADAM module into engineering quantity for calculation

the main technical indicators of the module: the accuracy is 16 bits, 3000V DC isolation protection, the communication address is arbitrarily set by the software, and the type of input/output quantities can be arbitrarily selected

IV. system software and functions

the software of this system is developed under the Windows95 platform by using vb4.0. The control part of the software is programmed with adam4000series for Windows API function by using VB until the test piece is crushed. The programming is flexible and convenient. The software adopts modular programming structure. The whole software is divided into main program, five subprograms and several public processes

1. main program block: the main program block mainly completes the connection with each subroutine and calls it according to the functions on the main menu

2. routine sewage treatment subroutine: This program block mainly completes the flow Q2 of the water to be treated, the seepage purified water flow Q1 and the concentrated water flow Q3 of a part of the discharge. The recently edited articles are the proportion control between high-quality and high-knowledge articles. At the same time, the pressure on the upper, middle and lower parts of the model group should be detected and calculated to determine whether it operates under the allowable pressure conditions. If it exceeds the allowable range, To adjust the pressure, if the adjustment is invalid, the alarm stops

3. backwashing and washing subroutine block: complete the constant flow control of backwashing flow and washing flow and the control of the liquid level of the water purification tank for washing

4. chemical cleaning subroutine block: complete the constant flow control of acid and alkali and the constant flow control of water washing after alkali washing

5. system test subroutine block: before the automatic control of the system, the automatic working state test must be carried out on all devices and equipment in the system to ensure the smooth progress of the automatic control of the system

v. function of control system

1. Dynamic display of process flow: animated display of the working state of the whole system on the computer screen, dynamic digital display of flow, pressure, liquid level, turbidity, output value of regulating valve and switching state of solenoid valve

2. Parameter setting and modification

3. control of liquid level, turbidity, flow and pressure

4. it is necessary to compare the changes of the old and new standards, and the display and storage of pressure and flow change curves

5. Fault alarm and handling

6. Data acquisition and communication

7. query management of key data and print reports

VI. other parts of the control system

in order to make the module work reliably, in addition to using precision switching power supply to supply power, the supply voltage should also be monitored. This is because although ADAM4000 series modules have 3000V DC isolated input withstand voltage, the increase of its power supply voltage will damage the module

, and this voltage rise is often ignored. The allowable supply voltage range of the module is: +1

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