Water Level Sensor – Optomax Digital Range of Liquid Level Switches12 5.4.. The information of the system also be shown on the screen include the work flow of the system.This mini projec
Overview
In industrial process engineering, mixing is a unit operation that involves manipulation of a heterogeneous physical system with the intent to make it more homogeneous Familiar examples include pumping of the water in a swimming pool to homogenize the water temperature, and the stirring of pancake batter to eliminate lumps (deagglomeration) Mixing is performed to allow heat and/or mass transfer to occur between one or more streams, components or phases
Modern industrial processing almost always involves some form of mixing Some classes of chemical reactors are also mixers With the right equipment, it is possible to mix a solid, liquid or gas into another solid, liquid or gas.
A biofuel fermenter may require the mixing of microbes, gases and liquid medium for optimal yield; organic nitration requires concentrated (liquid) nitric and sulfuric acids to be mixed with a hydrophobic organic phase; production of pharmaceutical tablets requires blending of solid powders The opposite of mixing is segregation.
The type of operation and equipment used during mixing depends on the state of materials being mixed (liquid, semi-solid, or solid) and the miscibility of the materials being processed In this context, the act of mixing may be synonymous with stirring-, or kneading-processes In this project, the substances which are mixed is the liquid – liquid. Mixing of liquids occurs frequently in process engineering The nature of liquids to blend determines the equipment used Single-phase blending tends to involve low- shear, high-flow mixers to cause liquid engulfment, while multi-phase mixing generally requires the use of high-shear, low-flow mixers to create droplets of one liquid in laminar, turbulent or transitional flow regimes, depending on the Reynolds number of the flow Turbulent or transitional mixing is frequently conducted with turbines or impellers; laminar mixing is conducted with helical ribbon or anchor mixers Mixing of liquids that are miscible or at least soluble in each other occurs frequently in process engineering (and in everyday life) An everyday example would be the addition of milk or cream to tea or coffee Since both liquids are water-based, they dissolve easily in one another The momentum of the liquid being added is sometimes enough to cause enough turbulence to mix the two, since the viscosity of both liquids is relatively low If necessary, a spoon or paddle could be used to complete the mixing process Blending in a more viscous liquid, such as honey, requires more mixing power per unit volume to achieve the same homogeneity in the same amount of time.
Project Objective and Scopes
The objective of this mini project is design an scada system and design an HMI touch panel for mixing system With scada system, the user can follow and observe whole system parameters For control those parameters, system need an HMI screen to adjust that value The information of the system also be shown on the screen include the work flow of the system.
This mini project just limit in the mixing field, at the basic of the mixer system.
By that, the acknowledge for mixing system in particularly and the scada system in general will be more clearly and easy to be acquired Beside that, HMI touch panel(HMI screen) also been created The HMI can help supervise and acquire the control data These HMI screen can be replace by the computer desktop with bigger screen.
Design Requirements
For this mixing system, the system can work properly In addition, the system have to detect these following trouble and show on the screen what is going on with the system as following:
- When 2 pumps of mixer tank ran after 3 times, light 3 will be on A reset button will reset the light.
- Can set the liquid level of storage tank, when the level at 5000 liters, blink the yellow light, at 8000 liters blink the red light.
- The mixer run in 10 second, after 10 second, the valve open to drain out the substance in the mixer tank.
- The supervisory and acquisition data control can be adjust through the HMI.
System Operation and System Configuration Selection
System Operation
At initial, the system will not run until the START/STOP button pressed After the whole system run, ON/OFF will be pressed to enable two digital level sensors in the mixer tank while the tank radar sensor (analog sensor) measure the level of the liquid in the storage tank We set the high limit level the level of the liquid in the storage tank will show on the HMI screen If the level is over the limit, the system will alarm to the operator While the tank radar sensor do its work, two digital level sensors in the mixer tank will detect the level of the liquid inside If the liquid at the low level,two pumps will be enabled and pump the substance to the mixer tank until the substance hit the high level sensor, two pumps stop and mixing process will be start.The mixer will run in 10 second, after 10 second, the mixer stop and valve will be opended The liquid after mixing will be transferred into the storage tank When the substance in the mixer tank drain out and hit the low level sensor, two pumps will continue its cycle Until two pumps run 3 times (this times can be change depend on the request of the customer), light 3 on the HMI screen will be light on There is a reset button to do the job reset that light.
System Configuration Selection
Centralized I/O circuits are plugged directly into the computer via extended buses The feature of this type are: small, highest speed of collect signal and control, low so beacause its commonly used This system are commonly used in the PC application which are nearby the sensor and the executive structure The system block diagram is shown in the Figure 4.2.
About PCI Card PD2 – AO – 16/16:
- This is PCI Card have 16 channel, 16 bit with 100kS/s speed for each analog out channel
- 16 analog out channel with 16bit resolution
- 3 interrupt input/clock, 3 timer/counter 24bit
- Independent waveforms in each channel
- Simultaneous update of channel, function update according to the external event
- 2k caching memory onboard (upgrade to 64k samples)
Figure 4.1: PCI Card PD2-AO-16/16
Figure 4.3: Block diagram of Power DAQ - AO - 16/16 and -32/16 boards
Sensors and actuators are commonly far from PCs In industrial environments,sensors and actuators are in harsh environments and cover hundreds of meters away from PCs.
In the noise enviroments, its hard to receive the small signal from the sensor as thermocouple, strain gauge through the long transmition.
The rope connect from sensor to PC is long and maybe expensive So there is a solution for this type: the distrubuted I/O mean that the signal conditioning modules are placed nearby each sensor corresponding For each sensor, they need one signal conditioning module With this solution can be costly if there are multiple sensors but its can be offset by signal and precision.
The common form of distributed I / O is a digital transmitter This digital transmitter performs all the necessary signal conditioning functions, with VXL and ADC to convert the signal to be measured into digital form This digital signal is transmitted to PC by RS-232 or RS-485 standard.
RS-232 (point to point): bulky when there are have many point
RS-485 (multi-drop): reduce the transmission cable, can connect up to 32 modules, transmission distance can be up to 10km if use multi-drop network (RS-232 maximum is 15m)
Usually we need an adapter to convert RS-232 to RS-485 because almost PC did not support the RS-485 standards.
Figure 4.4: Block diagram 4.2.3 Distributed Or Independent Data Collection And Control Units
The advantages of this type is likely the advantages of Distributed I/O with smart signal conditioning, beside that the ability to make remote decisions for itself increases system reliability.
Can control and setup configuration from PC using series communication orPCMCIA card It can work independently without PC (this is the main object of this type), so that its very useful when place the DAQ far away or in harsh enviroment or application do not allow the continuos connect to the PC For example is temperature control in refrigenerated truck.
Figure 4 5: Using PCMCIA card to collect the data from stand-alone
Figure 4.6: Stand-alone data collector via RS-232 serial communication
Figure 4.7: Connect the Stand-alone data collector via the telephone network or radio
Figure 4.8: Distributed data collection system
This communication standards is called GPIB (General Purpose Interface Bus), its was founded by Hewlett-Packard to connect and control the measure equipment test programming This standards fastly accepted by the world and become a IEEE-488 standards by speed, flexibility and useful in the connection of equipment in lab together
GPIB is a communication standards high speed parralel allow connect simultaneous 15 devices on data transmission parralel bus.
Usually request having a GIPB to locate the adress for each devices The maximum communication speed, the maximum transmission cable length and the maximum distance between devices depend on the speed and ability of GPIB processing and the cable transmission type.
This type suitable for research lab or test measure in industry There are a thousand product on the market support this type (IEEE-488)
Figure 4.9: Structure of one commonly GPIB system
Because of the sensors and acutuals are far away from the PCs so the suitable configuration for this system is Distributed I/O With analog sensor, the tank radar sensor is a sensor with transducer integrated inside The transmitter module will be placed nearby the sensors and actuals.
Component Selection
SIMATIC CPU S7 – 300 315-2 PN/DP (6ES7 315-2EH14-0AB0)
Siemens AG is a German multinational conglomerate company headquartered in Munich and the largest industrial manufacturing company in Europe with branch offices abroad Siemens offers a wide range of electrical engineering- and electronics- related products and services Its products can be broadly divided into the following categories: buildings-related products; drives, automation and industrial plant-related products; energy-related products; lighting; medical products; and transportation and logistics-related products Siemens drives, automation and industrial plant-related products include motors and drives for conveyor belts; pumps and compressors; heavy duty motors and drives for rolling steel mills; compressors for oil and gas pipelines; mechanical components including gears for wind turbines and cement mills; automation equipment and systems and controls for production machinery and machine tools; and industrial plant for water processing and raw material processing. Siemens also create the SIMATIC CPU such as S7-300 is a famous one in the series SIMATIC STEP 7 CPU
The SIMATIC STEP 7 series is at the middle to high end of the S7 range of [3] PLCs, it is the most commonly used controller across most industries for general automation There was a cheaper option in the form of an S7-200 (shoebox PLC) but this line is now discontinued and has been replaced by the far superior S7-1200 The main differences between an S7-300 and an S7-200 are:
- Cost the cost is generally higher for modules and equipment for the rack than it is for S7-200 but at the mid to low end of the range it is significantly cheaper than the S7-400
- The speed, 0.075ms - 0.018ms /1000 instructions-
- Built in memory (RAM), 32kB – 2.56MB
- Additional modules to the CPU 8 – 32
It is a modular series but not standard DIN mountable like the S7-200 or 1200 range, there is a special rail to be bought and fitted to your backplane to mount the S7-
300 racks S7-300 takes more space than a shoebox PLC series such as the S7-200 but much less than a rack mounted series such as S7-400 It is available in many different configurations to your choosing with additional modules available for:
- Digital I/O in multiple sizes from 8-64
- Analogue I/O sizes from 2-8 with hart communication
The system can be expanded to 4 racks in total with 1 master and 3 expansion racks Each rack is completely to your choosing up to a maximum of 8 usable modules per rack The main rack contains 10 with your CPU and expansion module taking up the other 2 slots and each expansion has 9 with the first slot being taken by the receiving expansion module (this is to a maximum of 32) All of this needs to be set up during the Hardware Configuration and must be downloaded to the PLC before downloading any blocks that use any address you may be adding otherwise when called this will put the CPU in stop.
The S7-300 CPUs come in a wide range of performance options with four different sections:
The PLC used in this mini project is S7 – 300 CPU 315-12 PN/DP 6ES7 315- 2EH14-0AB0
Figure 5.1: CPU S7-300 315-12 PN/DP 6ES7 315-2EH14-0AB0
HMI Touch Panel
A touchscreen, or touch screen, is a both input and output device and normally layered on the top of an electronic visual display of an information processing system.
A user can give input or control the information processing system through simple or multi-touch gestures by touching the screen with a special stylus or one or more fingers Some touchscreens use ordinary or specially coated gloves to work while others may only work using a special stylus or pen The user can use the touchscreen to react to what is displayed and, if the software allows, to control how it is displayed; for example, zooming to increase the text size.
The user interface or human–machine interface (HMI) is the part of the machine that handles the human–machine interaction Membrane switches, rubber keypads and touchscreens are examples of the physical part of the Human Machine Interface which we can see and touch.
In complex systems, the human–machine interface is typically computerized The term human–computer interface refers to this kind of system In the context of computing, the term typically extends as well to the software dedicated to control the physical elements used for human-computer interaction.
The engineering of the human–machine interfaces is enhanced by considering ergonomics (human factors) The corresponding disciplines are human factors engineering (HFE) and usability engineering (UE), which is part of systems engineering.
The SIMATIC HMI TP900 Comfort 6AV2124-0JC01-0AX0 is used in this mini project SIMATIC HMI TP900 is a comfort panel with touch operation and 9 inches widescreen TFT display Beside that, it also have 16 million colors, PROFINET interface, MPI/PROFIBUS DP interface, 12MB configuration memory, Windows CE6.0, (Mircrosoft Support, included Security updates discontinued) configurable fromWinCC V11.
Water Level Sensor – Optomax Digital Range of Liquid Level Switches12 5.4 Rosemount TankRadar PRO (Radar Level Gauge)
The Optomax Digital water level sensor (Figure 5.3) is ideal for applications with restricted space that require a miniature, low power and low cost sensing solution. The water level sensor is solid state, incorporating an infra-red LED and phototransistor which are optically coupled by the tip when the sensor is in air When the sensing tip is immersed in liquid, the infra-red light escapes making the output change state The liquid level sensor can detect the presence or absence of almost any liquid type; oil or water based The liquid level switch is insensitive to ambient light and is not affected by foam when in air or by small bubbles when in liquid.
The TTL compatible push-pull output can sink and source up to 100mA at a supply voltage range of 4.5 to 15.4Vdc and can be configured to output a high or low signal when in either a wet or dry state A fail-safe PWM option is also available with a supply voltage range of 4.5 to 5.5Vdc.
With housing options for internal or external sensor mounting and for use in two operating temperature ranges; Standard (-25 to 80°C) or Extended (-40 to 125°C).
The water level sensor is available in two chemically resistant housing materials, Polysulfone, the standard choice for most applications or Trogamid, which is typically used in food and beverage applications.
Applications in which the water level sensor can be used in can range from anywhere that requires detection of a leak or monitoring the level of liquid.
- Monitoring of fuel levels iin aircraft, vehicles and static equipment
- Low level indication of hydraulic fluid in equipment and vehicles
- Fluid level control in medical, industrial and domestic products
- Monitoring oil sump and bilge pump fluid levels
- Spa baths and hot tubs
- Tank and system level control
- Off-highway and agriculture vehicles
Figure 5.3: Optomax Digital Water Level Sensor 5.4 Rosemount TankRadar PRO (Radar Level Gauge)
The level of the liquid (or solid) is measured by radar signals transmitted from the antenna at the tank top After the radar signal is reflected by the liquid surface the echo is picked up by the antenna As the signal is varying in frequency the echo has a slightly different frequency compared to the signal transmitted at that moment The difference in frequency is proportional to the distance to the liquid, and can be accurately calculated This method is called FMCW (Frequency Modulated Continuous Wave) and is used in all high performance radar gauges TankRadar Pro uses the 10 GHz frequency band to get optimum balance between beamwidth and sensitivity to antenna contamination.
TankRadar Pro uses state-of-the art microwave technology to get highest reliability and precision It measures the level of liquids, slurries as well as many solids The gauge operates in a wide range of temperatures, pressures, vapor gas mixtures and various process conditions The applications include:
- Storage tanks at refineries and tank terminals
- Hydroelectric power generation and dams
- Cement, powder, wood chips and other solid material applications
In this mini project, TankRadar applications has been applied in tanks with agitators require a radar gauge with TankRadar Pro’s high sensitivity and advanced signal processing to separate the measuring signal from noise created by disturbances.
The TankRadar have each level for distance with a beam angle The beam angle as shown in the Figure 5.4.
Figure 5.4: Beam angle of TankRadar sensor
This TankRadar have the electrical connections, the Transmitter Head has two separate junction boxes One is for a non-intrinsically safe primary signal output and power supply cables The other is normally used for intrinsically safe (IS) HART/analog outputs or optionally for a non-IS analog output.
This TankRadar have the power supply is Ultra-wide 24-240V DC or AC 0-60
Hz With that power supply, the output of this sensor and measurement range are shown in the Figure 5.6 and Figure 5.7 respectively.
Figure 5.6: The main specification of TankRadar sensor
Figure 5.7: The measurement range of TankRadar sensor
With this TankRadar sensor, the system can measure the level of the liquid in the storage tank In industrial enviroment, the transmitter module will be place at the sensor to conditioning the signal and transmit to the PLC (CPU S7-300).
PLC Program
The PLC program are divide into 4 block: Main (OB1), Main Program Block (FC2), Alarms Block (FC1) and Storage Block (FC3) At the first scan, the system will scan the Main (OB1) If the START/TOP button pressed, 3 block: FC1, FC2 and FC3 will execute their function.
The state diagram of the system is show in the Figure 6.1 In the FC1 (Alarms Block), when START/STOP press, the FC1 will proceed and check the level of the liquid in the storage tank and the times of 2 pumps of the mixer tank run If the TankRadar sensor feedback the signal of the liquid level in the storage tank is low the process will be continue If not, the red light and yellow light will blink until the problems are solved At the same time the button START/STOP is pressed, the FC2 will proceed run the main system Two digital sensors will be scan the signal and send the signal back to the PC, if the level of the substance at the low level, two pumps will be activated and pump the substance into the mixer tank Until the high level sensor get the signal, two pumps stop and the mixer run in 10 second then open electric valve to transfer the liquid to the storage tank If the substance in the mixer tank are not detected by high level, two pumps still pump till the high level sensor detect the liquid. The whole process will loop until the START/STOP button pressed again
START/STOP button as a safety lock If this button are not being enabled,eventhough the On/Off button are press, the system would not run.
Figure 6.1: The state diagram of program
HMI Design
Design Requirement
The HMI for this system have to be simple The HMI must shown enough the information of the system on the screen, alarms for storage tank, real-time clock on the screen Beside that, the working process have to be shown on the HMI screen by simple animation The parameter of the storage can easily set and adjust.
Screen Hierarchy
The screen only have one main screen On the left hand-side, there are buttons of the system On the right hand-side, there are the indicators for the system and in the middle is the system sysmbol and animation The HMI design is shown in Figure 7.1.
On the top of mixer tank and storage tank, there are the box to show the run time of the mixer and the level set respectively The format of time of the mixer run is decimal and the level set of the storage as well On the top of the middle, there is a Symbolic I/O field The screen can be selected by clicking on the arrow and the list of the screens will be shown as in the Figure 7.2 By that, the operator can observe the whole system easily without missing any information.
In this HMI, there is no hierarchy between admin and operation because this system just a simple system and all control parameters will be control in the control room Beside that, the START/STOP button is one kind of hierarchy, the operation must know and understand clearly the system to operate it.
Date/Value Presentation
The real time clock are used, it can run simultaneous with the time of the PCs and it is placed on the right corner of the top In term of parameters, there is only the level of the liquid in the storage tank This level are set by the operator With the low limit and high limit of the storage tank, those parameters must be adjust in the PLCProgram The parameter on the HMI just only set the total capacity of the storage tank and it also can seem as the high limit as well For example, with the MW30 tag, 5000 liters is about 28086 value When the operator set the limit is 5000 liters, even though the value of MW30 get bigger, the value of the storage tank will not be change or get back to the 0 In this case the system will be stop its cycle (Figure 7.3).
Figure 7.3: The set value for 5000 liters
Alarms
The is three alarms for this system First is for the running times of two pumps for the mixer tank, second is the alarm for the liquid level in the storage tank. When two pumps of the mixer tank run after the running times we set, the indicator will light on For example, in this mini project, the running times has been set three times After three times, the cyan indicator will be light on as shown in Figure
Figure 7.5: The cyan indicator will light on after two pumps ran 3 times
For the alarms of storage tank, with the low and high limit has been already set in the PLC program, the yellow and red indicator will flash when the level of the liquid inside reach these limit The yellow and red indicator are displayed in the Figure 7.6 and Figure 7.7 respectively.
In the picture, the value of high limit of the storage has been set to 10,000 liters.
So the value on the slidec of MW30 will be different too At 5000 liters corresponding the value of the slidec is 13824, the yellow indicator will flash Until the level is 8000 liters corresponding to the value of slidec is 22119, the red indicator will flash and may the whole system will be stopped
Result
After design and program, the system work properly and doing well At first when the START/STOP and On/Off buttons are pressed, the running indicator change from red to green and ON/OFF indicator change the color as well If On/Off are pressed but the START/STOP button are not pressed, the system will not run.
Figure 8.1: At the begin of the system
Figure 8.2: After press START/STOP and ON/OFF buttons
After start the system, 2 digital level sensors in the mixer tank will check the level of the liquid inside The low level sensor and high level sensor detected result are shown in the Figure 8.3 and Figure 8.4.
Figure 8.3: Low level sensor detected
Figure 8.4: High level sensor detected, mixer run in 10 second
After 10 second, the valve open and the flow sensor detect the liquid inside the pipe, storage pump will be activated.
Figure 8.5: Valve open, flow sensor detect the liquid and activate storage pump
After the substance inside the mixter tank drain out and hit the low level sensor,the mixer tank will continue its cycle, two pumps continue pumps the substance into the mixer tank until the high level sensor detect and run the mixer.
Conclusion and Future Work
This mini project has been applied all knowledge about automation,SCADA, PLC and HMI design The system is created can be applied to the real system It can be upgrade or modify to make it appropriate with the using purpose of the customer
In addition, the author has been applied the knowledge which myself has been learnt into this mini project After complete the design of this system, author have a clearly view about what is SCADA system and how to do it, know how to use WinCC know what it is Beside that the system still need improve very much
The system need added more function and alarms to operate in the real-world test Such as the system can show how many times of the motor run to get the maintance point The adminstrator hierarchy is also needed too, and more screen for the system.
Finally, due to the limit of time, the mini project just done at the design and simulation the system This system has been modeled based-on the real model in the industrial With this system, the authors hope that can help everyone easy to understand the mixing system work.