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Petrochemical Industry

Transformation control system in natural gas compressor

Transformation control system in natural gas compressor

1. System overview


1.1 current status of equipment

1) The existing equipment system in the early 1990s, after more than ten years of operation equipment aging phenomenon is very serious, its control core PLC data is often lost, some automatic functions completely lost;

2) External detection components have not been calibrated for many years, and many components fail to detect, so it is difficult to accurately monitor the situation on the spot.

3) the original design is too complicated, with many detection points and redundant electrical control

4) due to aging, some functions of the control system fail and some completely lose their functions.

5), its equipment parts are basically eliminated, and once the parts are damaged, it is difficult to replace them, so it is difficult to maintain them.

6) The original system drawings and information are all in English, which brings great inconvenience to users and is not conducive to user maintenance and maintenance.



1.2 solution


Based on the above equipment, we consider replacing the original Schneider PLC with Siemens S7-300 series CPU and Uygur UN 300 series I/O, thus solving the above equipment problems.


Two, system requirements

2.1 hardware requirements:

1) replace the original "Schneider" PLC for SIEMENS S7-300 series PLC;

2) increase the EASYVIEW man-machine interface.

3) The original six instruments used for analog control and display were changed to UN300 A/D module control and displayed on man-machine and industrial computer.

4) Replacement of the original control cabinet, including low-voltage electrical appliances in the control cabinet, control system, PLC, control circuit, cabinet body, installation accessories, operation panel;

5), contactor and air switch are SIEMENS, button and indicator light are Schneider products.

6) maintain the hydraulic and pneumatic actuators of the system, including pressure and hydraulic valves.

7) the new control cabinet adopts the imitation map to make the cabinet, and the size of the cabinet remains unchanged.

8) Through the station control system of PROFIBUS standard fieldbus, the host computer is added to monitor the three units.

2.2 software requirements

1) realize the automatic function of the original unit through SIEMENS S7-300 programming software.

2) the human-machine interface has the following functions:

A) real-time data of unit operation.

B) and operation status of the unit;

C) and unit failure information;

D) and parameter setting of the unit.

E), unit control function.

3), Kingview:

A), state monitoring of the unit;

B) and process monitoring of the unit process.

C), engine compressor alarm stop point setting;

D), engine compressor fault stop point output

E), range setting;

F), implementing report output;

G), daily report;

H) and historical trend curve.

Three, system configuration and function realization

3.1 principle of equipment selection

1) equipment is selected by combining imported brand industrial control products with domestic brands.

2) domestic equipment is equipped with "3C" certified advanced, reliable industrial control products.

3) the control cabinet adopts the flame-proof structure with imitating structure.

3.2 main equipment and software

PLC: adopt S7-300 series PLC of SIEMENS company of Germany.

I/O: UN UNIMAT 300 series I/O;

Low voltage electrical appliances: basically use SIEMENS or Schneider Inc products;

Industrial control computer: Taiwan P4 industrial control computer.

Touch screen human-machine interface: MT510T touch screen of eView company;

Bus and communication protocol: adopting Siemens PROFIBUS standard fieldbus, CP5611 PCI card and PROFIBUS-DP standard communication protocol;


Kingview: kingview 6.5 version of Beijing Asian control company.



Hardware implementation


1) System constitution: According to the user, the upper computer is used to centralize the monitoring of all units, and a central control system is composed of PROFIBUS fieldbus, as shown in the following:

System composition diagram


I/O points: 1024 (max)

Storage capacity: 64KB

Processing speed: 0.3us/ step

MMC memory card, FLASH storage, data maintained for more than 10 years, and easy to replace, data will not be lost

The control core of the system, data processing and program operation, communication with man-machine, data exchange, with a DP port, good scalability

Analog input SM331

8 A/D conversion (3 standby)

The accuracy is 13 bits.


Analog input control, the original instrument control of the intake, outlet pressure and temperature digitization, through the PLC processing, can be on-site control and display on man-machine



SM321 digital input, SM322 digital output.

16, 24V, digital signal processing.

Human machine interface

10.4 ', 640*480, 256 colors.

Using Intel 32 bit processor.

Formula and real-time clock.

WINDOWS interface style


Display process parameters, historical data records, alarm records, process parameters can be modified.

* PC adapter

.MPI/RS232 conversion for PLC programming and man-machine communication

Industrial control computer

The IPC is Taiwan Advantech. The display is 21 inches of Philip.

PROFIBUS cable, PROFIBUS bus connector and CP5611 card.


3.2.2 software implementation:

Implementation of 3.4.1 configuration

The system interface is all Chinese.


It can dynamically monitor the current value of the process parameters of the compressor system and the working state of the technological process.

Can modify relevant parameters.

_can improve the self-diagnosis ability of the system, fault information is all processed in Chinese, and give warning display;


1) main screen:

All the analog parameters of the three units are monitored dynamically and real-time, so that the operator can master the operation status of all the units in the central control room.

Master picture

A) user login authority.

B) simultaneously displaying two engine, compressor operation parameters online.

C) record the engine running time.

D) record engine cumulative running time.


2), process gas flow monitoring screen:

Monitoring picture

A) dynamically display the operating parameters of the process gas on line.

B) has the animation display compressor unit technological process.

C) simultaneously displays the engine and compressor shutdown values, so that the operator can compare the operation data of the units.


3), engine compressor alarm stop point setting screen, the administrator passes this.


The picture can realize on-line modification of the alarm stop point, so as to achieve a variety of process requirements:

Alarm chart

A) the function of setting up the engine and compressor alarm stop point (with system permissions).

B) has the function of recording and displaying.


4) engine compressor failure stop point output screen:

Breakdown stop graph


A) the function of modifying the setting values of engine and compressor stop points (with system privileges).

B) has the function of recording and displaying.

C) alarm release and alarm muffler buttons.

D) engine emergency stop button

5) range setting screen:

Range setting picture

A) has a set of measuring ranges for engine, compressor detection points (temperature, pressure, speed)

B) has system permissions.


6) implementation of the report output screen:

Report output diagram

A) print the current engine and compressor operating parameters.

B) is written according to the user's actual report format.


7) daily table query screen

Report query graph


A) provides daily printouts for inquiries.

B) is compiled according to user's daily report format.

8) historical trend picture:

Historical trend map

Provide inquiring engine, compressor history trend curve and print out.

Through the Kingview, the operator can understand the operation status of the unit in the central control room.

The cause of the obstacle is to make the unit fault faster and more convenient.


3.2.2 human-machine realization

Through the MPI protocol and PLC communication, EasyBuilder 500 configuration software to set relevant parameters, and man-machine to achieve the following functions:

1) running state picture to monitor the running state of single machine.

2) the fault monitoring screen is used to display the fault of the unit.

3) Parameter setting screen to set and modify the parameters of the unit (with operating authority, only the administrator can operate).


Implementation of 3.2.3 network

Through the PROFIBUS-DP communication protocol, the S7-300 and Kingview are linked together to form a network, and the network is configured with Siemens STEP 7 V5.2+SP1 to realize a complete system. As a server, the industrial control computer is responsible for collecting data of all units, generating reports and historical curves, saving all data, and modifying the control and parameter settings of the units through PROFIBUS bus.


Four. Use effect analysis:

This system uses the mature and universal type of Siemens CPU and UNIMAT I / O module, good interchangeability, can reduce the number of spare parts, save costs. And make the whole system structure compact system circuit greatly simplified, high reliability, can greatly reduce the failure rate and maintenance costs. From the unified transportation to the present, the running state has been good.

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PLC in asphalt emulsification equipment

PLC in asphalt emulsification equipment

The so-called emulsified asphalt is to melt the asphalt through the action of emulsifier and machinery. The asphalt is dispersed in a water solution containing a certain amount of emulsifier in the form of tiny droplets, forming an oil in water asphalt emulsion. The emulsion is liquid at room temperature. Modified emulsified asphalt is a modified asphalt mixture emulsion which has emulsified asphalt as the base material and bitumen modified material as the external modification material under certain technological process. After mixing, mixing and preparing, the modified asphalt mixture emulsion is called modified emulsified asphalt.




Current domestic technology status: before the founding of New China, only a few municipal engineering departments used a small amount of anionic emulsified asphalt, after liberation has not been exposed to this technology. Up to the late 1970s, in order to develop the application of this new technology in our country, the Ministry of Communications organized a collaborative group of "cationic emulsified asphalt and its road performance research" to tackle the key problems of this technology. The project was listed as a key scientific research project of the Ministry of Communications in 1981 and an energy-saving application project of the former National Planning Commission and the National Economic Commission in 1983. Now the National Highway Department has more than 500 sets of emulsified asphalt plants. The production technology of emulsified asphalt workshop has been improved continuously. The production of emulsified asphalt has gradually developed from open flow, experience control of oil-water ratio to sealed pressure control of oil-water ratio by flowmeter and then to computer automatic control of oil-water ratio and oil-water temperature. The production quality of emulsified asphalt and the increase of output have met the needs of highway engineering and maintenance engineering. With the development of emulsified asphalt technology and its extensive application in China, higher requirements for the quality and output of asphalt emulsion have been put forward. Asphalt emulsification equipment will change the current situation of varieties confusion, high failure rate and small output, and develop towards standardization and rationalization.

Fig. 1. Emulsified asphalt production equipment abroad

The emulsified asphalt equipment can be divided into three types: batch operation, semi-continuous operation and continuous operation. The batch modified emulsified asphalt production equipment mixes emulsifier, acid, water, and latex modifier in the soap mixing tank, and then pumps them into the colloid mill. Once a bottle of soap liquid is used up, then the soap solution is placed, and then the next tank can be produced. When used in the production of modified emulsified asphalt, according to the different modification process, latex pipeline can be connected to the colloid mill before or after the colloid mill, or there is no special latex pipeline, but manually add the prescribed amount of latex to the soap tank.




Semi-continuous emulsified asphalt production equipment, in fact, the intermittent emulsified asphalt equipment is more equipped with soap mixing tank, so that can alternately mix soap, to ensure that the soap into the colloid mill uninterrupted. At present, a large number of emulsified asphalt production equipment in China belongs to this type. Continuous emulsified asphalt production equipment, the emulsifier, water, acid, latex modifier, asphalt and other directly pumped into the colloid mill with metering pump. The mixing of soap liquid is carried out in the conveying pipeline.

Fig. 2. Advanced emulsified asphalt production equipment in China

The existing asphalt emulsifying equipment mainly relies on manual operation, and consists of several pumps and several material tanks containing asphalt, emulsifiers and finished asphalt emulsifying products. Material proportion is mainly added by manual allocation through operator's experience. The characteristics of simple control technology, extremely unstable product quality and low production efficiency have always troubled our country's highway builders and highway maintenance personnel, but also greatly increased the intensity of people's labor.




After Market Research and in-depth discussion with highway maintenance staff, we decided to design a new set of equipment with high degree of automation and significantly improved production efficiency while reducing the labor intensity of staff.




The following is a production process in the emulsified asphalt production process. We have adopted this production process, coupled with programmable logic controller, frequency converter, flowmeter, quantitative pump and other computer technology control units, to a very large extent, improved the existing production conditions and improved the quality of products.

Fig. 3. A commonly used emulsified asphalt production process.

The whole equipment is made up of over asphalt tank, emulsion mixing tank, finished product tank, speed regulating emulsion pump, shearing mill, finished product delivery pump, electric control cabinet, large floor pipeline and valve.




Features of the equipment: mainly to solve the problem of oil-water ratio, it uses two speed-regulating quantitative pumps, according to the oil-water ratio, adjust the speed of the quantitative pump to meet the proportion requirements, operation is both intuitive and convenient, oil and water through the two pumps into the emulsifier for emulsification.




The electronic control part takes the UN 200 series 224 PLC of Shenzhen UniMAT Company as the control core. The PLC has the characteristics of high control precision, sensitive response and excellent seismic performance. It has been widely used in road construction industry. It is composed of frequency converter, flowmeter, quantitative pump and all kinds of temperature, touch screen and pressure control equipment.




The remarkable feature of this system is that PLC control system with stable and reliable response and prompt response is introduced. At the same time, it is equipped with advanced control equipment such as frequency converter, touch screen and flowmeter, so as to ensure the fast and stable operation of the system.




As we all know, highway construction and highway maintenance are mostly outdoors, the environment is unparalleled by other industries, not only to withstand the wind and sunshine, but also to withstand the high temperature and cold, at the same time, most of the road construction equipment is mobile, and the vibration is very serious, therefore, we in the selection of components on the past. Considered, the year before last we made a road maintenance asphalt paver, its control system is the use of the company's 224 series PLC (DC24V power supply), the biggest feature of this equipment is installed in a car, all day with the car running around, tremors, but after more than a year of use The PLC has stood the test and is still working conscientiously. Therefore, in the asphalt emulsification equipment, we also selected the 224 series PLC of UniMAT company.




The 224 CPU has two communication ports, one is connected with touch screen, the other is used for program debugging. The two communication ports do not interfere with each other, which brings great convenience to debugging. It can not only control the equipment by touch screen, monitor the operation of the equipment, but also carry out PLC by STEP 7 MicroWIN SP9 programming software. Monitoring greatly facilitated the debugging of the equipment and improved the work efficiency.




The PLC control system adopts the UN 200 series 224 (order number is UN 214-1BD23-0XB0) CPU of Shenzhen UniMAT Company, with 4-channel analog expansion input module (order number is UN 231-0HC22-0XA0), 2-channel analog expansion output module (order number is UN 232-0HB22-0XA0) and necessary digital output input module. After debugging and using, the whole system shows excellent performance of sensitive response, high control precision and high production efficiency.




The control system of asphalt emulsification equipment is shown below.




The working principle of the whole equipment is not complicated, the key is the mixture control of asphalt and emulsifier, which is related to the quality of the product and the production efficiency, is the key to the control system, it needs to adjust the rotational speed of each material pump, and needs to timely and accurately handle the flow back from the scene. Pressure and temperature signals, according to the analog signal processed to further adjust the speed of each material pump, forming a fast and accurate closed-loop control.




This control system is equipped with touch-screen as the upper computer to facilitate users to modify parameters and hand automatic control. In order to realize the mixing ratio of asphalt and emulsifier, the system controls the asphalt pump and emulsifier pump by frequency conversion, and then carries on the closed-loop control through the data feedback from the flowmeter.

                           Figure 6, part of the program screenshots

Firstly, the output of finished product and the mixing ratio of asphalt emulsifier are set by touch screen. The operating frequency of the two pumps is transmitted to the speed of the converter of the two pumps by the two-channel analog output module (the order number is UN 232-0HB22-0XA0) with the analog signal of 4-20mA, and the output frequency of the two converters is 4-20mA. The signal is also fed back to the PLC's four-channel analog expansion input module (order number UN 231-0HC22-0XA0), which is displayed on the touch screen after calculation.




In order to facilitate users to monitor whether the system works correctly and to achieve closed-loop control, two flowmeters are installed in the pipeline. Both of them are connected to the PLC system by analog signals of 4-20 mA. The PLC adjusts the rotational speed of each quantitative pump according to the preset proportion of ingredients and production efficiency through the collected flow signals. To achieve stable product quality and reasonable arrangement of production planning purposes.




In order to facilitate the mixing of emulsifier and asphalt, the emulsifier tank is electrically heated with a power of 10KW. The temperature is collected by the temperature controller. At the same time, the alarm signal of the temperature controller is connected to the PLC control system. The temperature is monitored in real time to ensure the quality of the product to the greatest extent.




When the asphalt temperature in the raw asphalt tank is too high, the exhaust fan is stopped to reduce the air volume to reduce the temperature. When the temperature is lower than the working temperature, the exhaust fan is started. Because the user requests to control the temperature by the temperature controller, the alarm contact of the temperature controller is connected to the PLC system, and the final temperature is realized by the output of the PLC. Degree control.

Because asphalt is not only easy to solidify at room temperature, but also easy to plug the pipeline, the pipeline through which the asphalt flows is heated: the pipeline through which the asphalt flows is a double-decker pipeline (a thick tube is then welded, another tube is used at the corner to connect the outer pipeline), the inner laminar flow asphalt, the heat-resistant oil heated by the outer laminar flow, and the oil. At temperatures of about 200 degrees, an oil pump pumps the heated heat-resistant oil out of the small furnace of the bituminous tank of the raw material and then delivers it to all the outer layers of the asphalt pipeline. In order to avoid asphalt blocking the pipeline, on the one hand, it is necessary to heat the pipeline through heat-resistant oil before work, on the other hand, there are strict requirements for the start-up and stop sequence of each pump and shear mill.Figure 9, debugger debugging equipment

In order to facilitate debugging and use, the system set up manual and automatic mode, automatic control mode through PLC control, equipment in accordance with the pre-set operation mode.




Manual control when the user can start a pump alone, but the order of the pump start-stop requires the operator to operate strictly in accordance with the equipment production process, at this time, only the start-stop operation of the pump by the operator's own control, pump speed is still controlled by PLC settings parameters.




Equipment maintenance is not subject to any restrictions, in manual mode can be arbitrarily started and stopped each device (running without material).




Under normal conditions, the equipment runs in automatic control mode, debugs or maintains the equipment and uses manual mode in emergency.




After debugging and more than a month's application, the equipment, with its stable and reliable quality, fast and sensitive control speed, improves the output of the products, ensures the qualified rate of the products, reduces the labor intensity of the field operators, and brings very good economic and social benefits to the users, and wins the praise of the users.

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Application in oil and gas lubrication control system

Application in oil and gas lubrication control system

Abstract: This paper introduces the application of UniMAT PLC in the control system of oil and gas lubrication equipment. As a new type of lubrication technology, oil-gas lubrication is also known as gas-liquid two-phase fluid cooling lubrication technology, which uses compressed air as the carrier to transport a uniform, micro continuous oil flow to the lubrication point. Compared with the traditional thin oil lubrication and dry oil lubrication, oil-air lubrication has its incomparable lubrication effect, which greatly prolongs the service life of lubricating parts and reduces environmental pollution. UniMAT PLC is introduced into the oil-gas lubrication equipment as its automatic control core, which realizes the automatic operation of the equipment, precise control of air pressure and hydraulic pressure. The system is stable, reliable, easy to use and flexible to meet the needs of users.


Key words: oil air lubrication, UniMAT PLC, automatic control

1. Introduction

Oil-air lubrication system is a new type of lubrication technology, which is widely used in all walks of life of construction machinery. In recent years, China has accelerated the development and innovation of oil-air lubrication system. The perfect monitoring system and stable operation characteristics have become the key points to measure the excellent oil and gas lubrication equipment.


2. working principle

Oil-air lubrication is a centralized lubrication method, which uses continuous flow of compressed air to produce intermittent supply of thin oil to form swirling liquid droplets and transport along the pipe wall to the lubrication point. Compressed air is used to flow in the pipeline, which drives the lubricating oil to flow continuously along the inner wall of the pipeline and conveys the oil-gas mixture to the lubricating point. Compressed air is supplied continuously at a constant pressure of about 0.3-0.4 MPa, while lubricants are supplied quantitatively according to the amount of friction consumed. Therefore, it is necessary to use the oil pump as the power source of oil transmission, and the progressive oil feeder is used to supply the required amount of oil for each lubrication point. The principle of oil and gas mixing is shown in figure 1..

3. system composition

The system consists of electronic control device, oil supply device, oil filter device, oil distribution device, gas source treatment device, oil-gas mixing device, oil-gas transmission pipeline and oil-gas distribution device. The electronic control system consists of UniMAT PLC system, HMI system, low-voltage electrical apparatus, sensors and actuators. The configuration of UniMAT PLC system is shown in table 1..


Table 1:UniMAT PLC system configuration




Series No.





UN 214-1AD23-0XB0

 PCS 1

EM223 8DI/8DO

UN 223-1BH22-0XA0

 PCS 1

UniMAT CPU224 has the following advantages over similar products in the market: additional PPI communication ports are added to avoid the trouble of customers not using touch screen and programming cable communication ports at the same time, only plugging and pulling ports constantly; battery-free, power-down data can be maintained for up to 10 years; faster command execution speed A single Boolean operation instruction is three times that of a similar Siemens product; it is compatible with the Siemens S7200 instruction set; it can directly replace the Siemens 224 controller module. The appearance of UniMAT CPU224 products is shown in figure 2.

4. control process

The electrical control system of the oil and gas lubrication system is a PLC control system. The core is composed of upper computer and lower computer. The upper computer is UniMAT CPU224 PLC, and the lower computer is LCD touch screen or HMI. The user interface is friendly and easy to operate. The LCD touch screen can display all kinds of setting parameters and running state of the system. Users can change the local mode, remote mode and testing mode of the system. Users can also modify the system parameters according to actual needs, and display the fault location and report when the fault occurs. In addition, the password protection function also requires the user to change the system settings when identifying parameters to ensure that the system is not random operation. The control process diagram is shown in figure 3..

There are three kinds of medium in oil-gas lubrication system, namely oil, gas and oil-gas. A perfect oil-gas lubrication system should have the function of monitoring these three kinds of medium to ensure that all parts of the system are known about their operation status. Once the fault occurs, the fault signal can be sent out in time to avoid serious consequences.


The main contents of the monitoring system are as follows:

Monitoring of oil: level switch monitors tank level, alarms when liquid level is low, stops pump when liquid level is too low; pressure switch detects oil pressure, controls pump start and stop according to oil pressure; temperature controller detects oil temperature, controls heating rod start and stop according to oil temperature; proximity switch monitors progressive distributor itself and its upstream oil supply department. Whether the whole fuel supply process is normal or not.


Gas monitoring: Pressure switches monitor the pressure of compressed air, and can be used to determine whether the air filter element is blocked.


Oil and gas monitoring: there are two ways to monitor oil and gas, one is transparent hose, can intuitively observe the operation of oil and gas flow, economic and practical; the other is the flow switch, with LED display, can observe the change of oil and gas flow, oil and gas flow speed is too slow or stop, will send an alarm signal.


  Report errors



5.system effectiveness

The protection effect and economic benefit of the system are obvious.

1). The lubrication effect is satisfactory, which greatly prolongs the service life of the bearing.

2), greatly reduce the rate of sticky roll and reduce the consumption of waste and roller due to sticky rollers.

3), to prevent external debris and water intrusion into bearings is conducive to the bearing seal;

4), the consumption of lubricants is sharply reduced, which is only equivalent to that of dry oil lubricated 1/4.

5), the maintenance and operation costs are greatly reduced.

6). The processing cost of waste dry oil is zero continuous casting oil air lubrication technology.

7). The pollution of equipment running environment and cooling water caused by the leakage of dry oil has been completely eliminated, and the cost of water treatment has been reduced.


6.concluding remarks

UniMAT PLC used in oil-gas lubrication control system shows high compatibility with Siemens PLC and excellent performance stability. UniMAT PLC can completely replace Siemens products, ensuring the stability of the product while reducing the manufacturer's production costs.

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