Industrial Design Engineering
Study of PCM Power Plant
ANDERS WIBERG
Master of Science Thesis MMK 2010:13, IDE 031 KTH Industrial Engineering and Management Machine Design
Master of Science Thesis
Abstract
A study has been made of a smaller power station on behalf of Exencotech who is researching energy-recycling possibilities. Their station extracts energy from heated water which otherwise would have been discarded as a loss.
The study has been conducted on a 100kW system with a high option of modularity which makes the system flexible and adjustable when installing. The study also treats a 5kW prototype and a modular version of the 100kW system up to 0,5MW. The application is designed to minimze the volume and weight of the system. It has also been analyzed ergonomically and in ways of its usability which has affected the design.
To define appropriate solutions for the project several concepts has been conducted as well as evalu-ations of solutions. As a prestudy for the project other power stevalu-ations has been looked at as well as control and surveillance systems.
A concept has been developed where the energy cell module (the module extracting energy) is de-signed to give 50kW (initially, though optimization will heighten this), using 9m3 volume, this is used
together with a water distribution module and a hydraulic module. As maintenance is meant to be easily performed, a special application has been developed which helps the procedure of access and extraction of desired parts whitout causing the operator too large ergonomical stress. The system is designed to be able to operate even when a part of it is shut down for repairs. The module has been constructed and dimensioned to withold the loads it would cause into the system
A graphic interface has also been designed to improve the usability and understanding of the system.
Approved Examiner Supervisor
Commisioner Contact person
Master of Science Thesis MMK 2010:13, IDE 031
- Industrial design engineering study of PCM power plant -
Anders Wiberg
Carl Michael Johannesson Carl Michael Johannesson
Exencotech AB Assar Svensson
Sammanfattning
En studie av en mindre kraftstation har gjorts i samarbete med Exencotech som forskar inom energi-återvinning. Deras kraftstation behandlar återvinning av värme från uppvärmt vatten som annars inte hade använts utan ansetts som ren förlust.
Den studie som genomförts har gjorts på ett 100kW system med en så stor möjlighet till modularitet som är möjligt för anpassning och flexibel installation. Studien har även innefattat en 5kW prototyp och en modulär version av 100kW systemet upp till 0,5MW. Applikationen har som krav att framför allt minska volymen och storleken på systemet. Studien innefattar även en ergonomisk och använ-darvänlig inriktning vilket har påverkat designen och konstruktionen hos systemet.
För att finna lämpliga lösningar och koncept till projektet har flera konceptgenereringar gjorts, liksom utvärderingar av lösningar. Som en förstudie till projektet har andra kraftstationer undersökts liksom deras kontroll och övervakningssystem.
Ett koncept har tagits fram där en energicells modul (delen som utvinner energi) är designad att ge 50kW (initialt, dock kommer detta öka i takt med optimeringar) och tar upp 9m3, denna används
till-sammans med en vattendistributionsmodul och en hydraulmodul. Då underhåll ska kunna genomföras på systemet har en speciell applikation tagits fram vilken underlättar arbetet med att komma åt och kunna byta ut delar utan att operatörens ergonomiska påfrestningar blir för stora. Modulen är kon-struerad för att kunna producera energi även om en mindre del av den stängs av för reparation. Ener-gicellsmodulens hållfasthet har studerats och analyserats för att klara de laster som systemet ger. Ett grafiskt gränssnitt har även konceptuellt tagits fram för att ge ett förslag på hur det skulle kunna designas för att förbättra användarvänligheten och förståelsen i kraftstationen.
Godkänt Examinator Handledare
Uppdragsgivare Kontaktperson
Examensarbete MMK 2010:13 IDE 031
- Industriell design-ingenjörs studie av PCM-kraftstation -
Anders Wiberg
Carl Michael Johannesson Carl Michael Johannesson
Exencotech AB Assar Svensson
Contents
Expressions and terms used in thesis - 11
1. Introduction - 13
1.1 Background - 13
1.1.1 Exencotech - 13 1.1.2 Describing the technology - 13
1.2 Problem definition - 13 1.3 Specification of requirements for the project - 13
1.3.1 Physical Design - 13 1.3.2 Interface design - 13 1.3.3 Time specifications - 14 1.4 Project limitations - 14 1.5 Project goals - 14 1.6 Project risks - 14 1.7 Methods - 14
2. Studies - 15
2.1 Patent search - 15 2.2 Existing power stations - 152.2.1 Organic Rankine Cycle - 15 2.2.2 Sterling Engine - 16 2.2.3 Kalina Cycle - 17
2.3 Potential users - 17 2.4 Regulations - 17 2.5 Existing solutions for graphical interface - 17 2.6 Surveillance system setup - 18
2.6.1 Communication protocols - 18 2.6.2 Control Unit - 19 2.6.3 Human Machine Interface - 21
3. Synthesis - 23
3.1 HMI - 23
3.2 Physical design of system - 33 3.2.1 System view - 33 3.2.2 Concept generating - 34 3.2.3 Choice of concept - 37 3.2.4 Concept optimization - 39 3.2.6 Rack design - 49 3.2.7 Beam-structure configuration - 50 3.2.8 Development of extraction device - 50 3.2.9 Final design of the system - 52
3.3 Dimensioning - 54
3.3.1 Beam structure design - 54 3.3.2 Rack design - 60
3.3.3 Extraction device - 64
4. Results - 67
4.1 Drawings - 67
4.2 Usability analysis - 67
4.2.1 Gestalt grouping rules - 67 4.2.2 Figure and ground - 69 4.2.3 Occlusion - 70
4.2.4 Conclusion - 70
4.3 Ergonomic analysis - 70
4.3.1 Removing front encasement - 71 4.3.2 Pulling out device and rack - 72 4.3.3 Lifting energy cell out of frame - 72
5. Conclusions - 73
6. Discussion - 75
7. References - 77
8. Thanks - 79
Expressions and terms used in thesis
A/D - Analog/DigitalCPU - Central Processing Unit
EC - Energy cell, an invention of Exencotech’s which is the energy generating part of the process. HART - Highway Addressable Remote Transducer.
HMI - Human Machine Interface, the interface making it easier for the operator to control a machine. I/O - Input/Output
ORC - Organic Rankine Cycle, process using PCM.
PCM - Phase Change Material, material used to exact energy when changed in phase. PLC - A device used to control technical systems, short for Programmable Logic Controller. QFD - Quality Function Deployment, method of weighting concepts.
rpm - Unit, meaning rounds per minute. RTU - Remote Terminal Unit.
1. Introduction
1.1 Background
The power station Exencotech is developing will be able to recycle heat from waste water, produc-ing mechanical energy. Factories often dump their temperate waste water without recyclproduc-ing the energy it holds, typical temperatures can be about 50 degrees Celsius. At the moment there are no similar products on the market able to recycle heat below 50 degrees. Some of the manufacturers however use their waste water to pre-heat their incoming water which recycles a part of the energy otherwise lost.
1.1.1 Exencotech
Exencotech is a company founded by Assar Svensson and Bengt Östlund in 2007. The company is currently researching different solutions to extract energy from heated waste water by using phase-changes in materials.
1.1.2 Describing the technology
As a large part of Exencotechs work are patented or pending patents it cannot be described in detail, this is no problem since the thesis does not include work on the actual patents but rather uses them. However a basic view of the system can be described (see Figure 1.1).
Figure 1.1, Illustration of the systems subsystem.
Heated (waste) water is led through a heat exchanger since a closed water system is desired, in the same way the cooling water is fed to the application. This water is then pumped throughout the system in two phases, first a heating phase and later a cooling phase. The water is led through what is called an energy cell which extracts the energy from the heated water and is restored for the next cycle by the cooling phase. A hydraulic system as well is then used to convert the energy into the desired output.
1.2 Problem definition
The thesis shall result in the conceptual design of the power stations exterior, as well as the rack holding the included parts. This should be designed to simplify maintenance and increase accessi-bility. Other prioritized areas are minimizing the weight, size and cost of the application. This is to be used as a basic study for later development. Also the surveillance options of the station will be studied and a conceptual graphical interface shall be designed to simplify the control of the station.
1.3 Specification of requirements for the project
For more specific details see appendix A.
1.3.1 Physical Design
other components included in the product, while giving the system the best possible conditions. Said rack should be able to work for a smaller prototype, while still being able to be used in a larger scale. The system will also require an outer casing, with a design which is expected to make possible buyers of the product easily understand and aesthetically appreciate it. The system shouold also be designed to make maintenance simple to perform and easily understood.
1.3.2 Interface design
Propose methods and techniques for monitoring and surveillance both on site and remotely, this by re-searching what options are available. Since the systems are similar apart from their sizes the interface should be made to fit the 5 kW prototype as well as the 100 kW system.
Draw a conceptual interface design for the monitoring system.
1.3.3 Time specifications
The project started in August 2009 and continues to January 2010 and should represent a 20 week project. A time schedule is included in appendix B.
1.4 Project limitations
For the physical design of the power station the use of standard components were always desired to reduce cost. The project will present a finished concept of the system, or if the system is split into sev-eral parts, the unit where most of the specification of requirements can be fulfilled is prioritized. The design should concentrate on a 100kW system but if possible be able to apply to the 5kW proto-type which is now being produced.
The interface will be a conceptual design, made to highlight the graphics of the interface.
1.5 Project goals
The goal of the thesis was to present a solution which fulfilled the specification of requirements. The concept shall be constructed and analyzed to a depth which will help the coming final design and pro-duction of the system.
1.6 Project risks
Different risks which could make the project more difficult were analyzed and for those with a high risk or consequence, a plan of action was drawn up, see appendix C.
1.7 Methods
To ensure that the project will reach its goals a number of methods are chosen to help the work. The methods also contain several computer programs which will be used in the process.
• A literature study will be made to study different solutions in smaller power stations. • The parts included in the power station will be studied for a greater understanding. • Brainstorming shall be used to create concepts.
• To visualize said concepts Rhinoceros 3.0 [1] will be used along with hand-drawn sketches and Adobe Illustrator [2].
• An ergonomic study will be made on chosen design with the help of manikin software Jack [3]. • An usability analysis will be made of the developed HMI design
• Quality Function Deployment will be used to evaluate solutions
• A decision matrix will be used to choose a final design from the different concepts.
2. Studies
A study is made to find what similar products are availiable and to gather information in ways to control and surveill the system.
2.1 Patent search
A patent study was made to map different solutions for the problem of waste heat recovery. A pat-ent was found from 1988 [5], with a similar purpose. This product was a form of an Organic Rankine Cycle (see Section 2.2.1). The ORC was first developed in the sixties and has been further developed since. An interesting piece concerning this patent is its modularity which is preferable in the object of this thesis work.
A modular, frame-mounted power unit for converting heat from a low-grade energy source to electric power. Heat from a source is supplied to the power unit in the form of hot fluid circulat-ed through a heat exchanger associatcirculat-ed with a boiler. Liquid refrigerant in the boiler is vaporizcirculat-ed and passes through the stages of an organic Rankine cycle, the expansion stage being carried out in a rotary, positive displacement expander.
The condensing stage is carried out in a condenser associated with a cold heat exchanger which is connected to a supply of cooling fluid through cooling lines. The output shaft of the expander is connected to drive an electric power generator and individual fluid feed pumps for returning liquid refrigerant from the condenser to the boiler and for circulating hot and cold fluids through the hot and cold heat exchangers, respectively.
A cylindrical refrigerant boiler and cylindrical condenser pass through and are mounted to two vertical plates, on which are mounted the expander, power generator, fluid circulating pumps, and feed pumps.
The article does not however claim how much power it generates and neither does it specify the size or weight.
2.2 Existing power stations
The different ways used to recover heat energy from waste water are mostly in the form of a heat ex-changer. A heat exchanger could use the heated waste water to preheat another fluid or gas before its being used. However, most uses exhaust-gases as the heating medium.
While Exencotechs solution is able to recycle heat as low as 25 degrees Celsius, be it with a lower efficiency than with a higher temperature, there exists a process called ORC (Organic Rankine Cycle) which claims to be able to recycle heat waste water for temperatures as low as 50 degrees.
Other ways to recycle energy is by using a Kalina cycle or a Sterling engine. These are however not as commonly used as the ORC.
2.2.1 Organic Rankine Cycle
Model Heat source temperature Flow rate of water Size of device Net Energy generated
Exencotech 25 – 75 Celsius 30 m3/h 25-30 m3 100 kW*
ORC
Opcon 50 – 120 Celsius 90 – 360 m3/h 75 m3 650 kW (400)
Infinity Turbine Min. 90 Celsius 9,6 m3/h Est. 5 m3 10 kW
Tri-O-Gen Min. 350 Celsius N/A 35 m3 60 – 160 kW
Turboden Min. 260 Celsius N/A (Oil) 135 m3 550 kW
Maxxtec Min. 300 Celsius N/A (Oil) N/A 550 kW
Ormat N/A N/A N/A N/A
Table 2.1, list of different ORC-units compared to Exencotechs solution. * Exencotechs application will, with the same size of the unit be able to produce a higer energy when its optimization is final.
Of the five ORCs which can be compared there is only one which claims to recycle heat from tem-peratures as low as 50 degrees Celsius while Exencotech can use temtem-peratures down to 25 degrees Celcius. The net energy output must of course be comparable to the units’ heat source and the amount of heat used to be able to compare efficiencies.
Opcon
A company named Opcon [6] manufactures an ORC application which needs waste water heated to between 50 – 120 degrees Celsius they then claim to being able to extract 650kW with a mean value of 400kW. It uses a flow rate of somewhere from 90 to 360m3/h.
Infinity Turbine
Infinity turbine [7] has a small, 10kW system which operates on 90 degree waste water using 9,6m3/h.
It is a relatively small unit but is possible to increase by scaling, for higher output.
Tri-O-Gen
The company named Tri-O-Gen’s [8] ORC is of the same size as Exencotechs, though the heat source needs to be at a minimum of 350 degrees Celsius. It offers up to 160kW of energy.
Turboden
Turbodens’ [9] Rankine cycle is not heated by water but instead evaporates an organic fluid with high molecular mass, which is used throughout the system. It operates with a Heat source of minimum 260 Celsius, while generating 550kW energy. The size is however quite large, using 135 m3.
Maxxtec
An ORC similar to that of Turboden is Maxxtec [10] which uses biomass combustion gases of up to 950 degrees Celsius to warm a thermal oil circuit. The circuit is heated to 300-330 Celsius. This in turn is used as the heat source for the ORC generating about 550kW.
Ormat
Ormat [11] is one of the leading producers of ORC technology, however the search for comparable data has been futile and thus is not compared.
2.2.2 Sterling Engine
closed system. At the first position the medium is in contact with a heat source, which heats the me-dium, making it expand. This causes the medium to push a piston through a cylinder, which generates energy, the space that opens up from the cylinder is in contact with a heat sink. With the same motion pushes another piston to press the medium away from the heat source. At this position the medium is mostly in contact with the heat sink, which compresses the medium making the first piston to go back to its original position, which leads to a cycle. There are several different types of sterling engines, and this is one of the most basic.
2.2.3 Kalina Cycle
The Kalina cycle uses a mixture of fluids as a medium, which offers the possibility to change its boil-ing point by tweakboil-ing the concentration of the substances. Often these are a mixture of water and am-monia. The cycle is (simplified) in the first moment the medium in a boiler is heated by a heat source which could be exhaust gases. The medium is vaporized and expands through a turbine. It is then cooled when a separator has sifted out the different substances to new concentration-levels, making it easier to condense. It then adds the fluids to generate the first mixture again and the process is cycled.
2.3 Potential users
The potential users of the product should be all kinds of facilities which have surplus of heated waste water. Possible users could be existing power plants or paper-mills. The product is most easily con-nected off-grid while on-grid is also an alternative.
2.4 Regulations
Due to the fact that a number of the devices in the PCM-engine are operating under a significant hydraulic pressure there are some regulations from Arbetsmiljöverket (Swedish Work Environment Administration) to consider. First and foremost the energy cells themselves have a number of require-ments to fulfill from AFS 1999:4 [12]. This regulation defines the detail as approved, while AFS 2005:2 defines a facility. The second need not be applied when the first is, which renders it unheeded. The physical casing enclosing the devices however do not have to heed any specific regulations when the devices themselves are approved by AFS 1999:4, although some of the their rules can be extended to the casing.
1. The method of operation specified for pressure equipment must be such as to preclude any reasonably foreseeable risk in operation of the equipment. Particular attention must be paid, where appropriate, to […] devices to prevent physical access whilst pressure or a vacuum exists
A casing should help to prevent any physical access whilst pressure exists in the process.
2. Pressure equipment must be designed and constructed so that all necessary examinations to ensure safety can be carried out
3. Adequate means must be provided for the draining and venting of pressure equipment where necessary
2.5 Existing solutions for graphical interface
To monitor and control the different sensors and valves that are required in the PCM-engine there are several solutions. A SCADA (Supervisory Control And Data Acquisition) system is used to interpret the communications from the PCM-engine and translate it into a graphical interface HMI (Human-Machine Interface). Alternatively a web-based HMI-system can be used.
2.6 Surveillance system setup
There are several possible setups to construct the system. The different signals, sensors, valves etc. can be read by either a fieldbus-system or an analog Current Loop (4-20mA). The analog signal can be converted by a HART-device (Highway Addressable Remote Transducer) to a digital one. These readings are sent to a PLC (Programmable Logic Controller) or a RTU (Remote Terminal Unit).
2.6.1 Communication protocols
The hardware used to extract the signals from the sensors often vary between a Current Loop and a Fieldbus-system.
Current Loop
To extract the sensors and valves readings an analog Current Loop can be used. It uses the absence of current for high, and the presence of current in the loop for low. This means that only one current level can be used at any time. The Current Loop is easy to understand as they would only require a simple multimeter, measuring the current, to debug.
The Current Loop can be used together with a HART-protocol to convert it to a digital signal, thus making it possible to use multi-drop (maximum of fifteen devices) which allows several devices to be connected through the same wire.
Fieldbus
The alternative to the analog signal would be to use a fieldbus-system. These use different protocols, for example Foundation Fieldbus and Profibus which are not perfectly compatible with each others devices (sensors etc.).
The differences between the Current Loop and the fieldbus are explained in this quote:
Previously computers were connected using RS-232 (serial connections) by which only two devic-es could communicate. This would be the equivalent of the currently used 4-20 mA communica-tion scheme which requires that each device has its own communicacommunica-tion point at the controller level, while the fieldbus is the equivalent of the current LAN-type connections, which require only one communication at the controller level and allow multiple (100’s) of analog and digital points to be connected at the same time. This reduces both the length of the cable required and the number of cables required. Furthermore, since devices that communicate through fieldbus re-quire a Microprocessor, multiple points are typically provided by the same device. Some fieldbus devices now support control schemes such as PID control on the device side instead of forcing the controller to do the processing. [13]
Figure 2.1, Network topologies available for fieldbuses: Ring, Star, Line and Tree [14]. Pricing Analysis
Regarding the costs of the different systems a web-page listed this as a comparison between the differ-ent Communication Interfaces.
Pricing varies enormously based on customers, geographic regions, and features. However, 4-20 is the cheapest, with 4-20 mA with HART being more expensive. Further, FOUNDATION and PRO-FIBUS are costlier than HART. For instance, a pressure transmitter can have four different prices depending on whether is it 4-20 mA, 4-20 mA with HART, profibus and FOUNDATION fieldbus. The other factors that determine price are accuracy and end-user requirements. [15]
The pricing comparison between analog and digital signals depends on the physical size of the sys-tem. If there are long distances which need to be wired there is a greater need to use the same wire for multiple signals, if the wiring is mostly short distances (like the 5 kW prototype case) the added expense of a fieldbus system is not justified by the cabling expenses. Another reason to use a fieldbus is if the numbers of I/O are high enough to ensure a lack of places to fit the wires to/from the PLC.
2.6.2 Control Unit
The PLC-device is often used in industrial manufacturing processes where the development cost of the automation and maintaining is high relative the total automation cost. It is also appropriate to systems where changes are expected to be made during its operational life. One of the protocols most used for the PLC-devices is Modbus which is openly published and royalty free, also often used is Profibus DP. For a list of PLC units see Table 2.2.
PLC
Expandable I/O, analog through converter-module
Integrated I/O
(digital, analog) Communication over distance
Mitsubishi FX3UC 32MT 384 total digital, N/A 16/16, 0/0
Ethernet module: FX3U-ENET RS-422: Built-in Mistubishi FX3UC 64MT 384 total digital, N/A 32/32, 0/0
Ethernet module: FX3U-ENET RS-422: Built-in ABB AC31 07 KT/KR 51 >1000 total digital, 544/136 analog 8/6, 0/0 Ethernet module: e-AC31 RS-232: Built-in Toshiba * V2000 S2T 2048 total digital, N/A 0/0, 0/0 RS-485: Built-in Toshiba T1-40S 72 total digital, N/A 24/16, 0/0 RS-232: Built-in RS-485: Built-in Omron* CJ1GCPU45P 1280 total digital, N/A 0/0, 0/0
Ethernet module: CJ1W-ETN21 Omron
PLC Expandable I/O, analog through converter-module Integrated I/O(digital, analog) Communication over distance
Siemens S7-300
CPU313C 992/992 digital,248/124 analog 24/16, 4/2 RS-232, RJ45 module: TIM 3V-IE Modicon M340 *
BMX P34 10
512 total digital, 128/66 analog
N/A Ethernet module: BMX NOE 0100
Table 2.2, List of PLC units, * indicates a modular product which needs external modules of I/O. Programming
There is a standard for programming languages on PLC’s, named IEC 61131-3. It defines five differ-ent languages, among them one similar to Pascal (Structured Text) and another similar to Assembly (Instruction List). If a fieldbus system is used the devices need to be programmed to interact with each other using certain protocols specified to the items. An analog signal is programmed to receive the current from the I/O and related to each port to define which device is which. When analog cur-rent loops are used (without a HART-device) an AD-converter must be used to convert the signals to digital form, these are separate elements which are connected to the PLC.
I/O
I/O stands for Input/Output and defines the number of possible signals the PLC can receive/send at a given time. If current loops are used the I/O are of analog sort and will have to be translated by an A/D-converter for the PLC. Some of the PLC’s are of modular design which makes it possible to de-sign the number of I/O along with other desirable features.
These modular PLC often have a number of built-in I/O, possibly both digital and analog. However, some of them only have I/O-modules which have to be fitted to its rack.
PID-control
A PID-controller is a control loop feedback mechanism which may be included in a PLC. It can be used to compensate the error which could occur if the input does not match the desired output. For example, if a temperature is to be set at a higher value than before and the PLC receives the input and raises the temperature a certain amount. This new value could be a too large and the computer lowers it, and this continues, possibly oscillating to an unstable system. A PID-controller’s algorithm calculates the error and compensates which gives a stable system and possibly faster and more exact control. A PID-controller is probably not an application which will be used in the project in its current system design.
Communication System
A PLC has built in communications ports, most often a standard RS-232, but optionally also an Eth-ernet port. The RS-232 is the most common standard to send serial binary data signals, while RS-422 and RS-485 are other similar standards. These use a different kind of signaling and have some other different attributes as well.
2.6.3 Human Machine Interface
The data received by the PLC are analyzed and a selected part will most often be sent to a Human-Machine-Interface which allows personnel to analyze and control the device. The HMI can be either a standalone program or a web-based one, whichever suits the user/producer best.
A smart HMI allows the user to easily find important values and gives the opportunity to tweak them (see Figure 2.2). It should however be possible to analyze more data if desired, for the operator.
Figure 2.2, Smart and easily understandable HMI. [16]
Many HMI’s are hard to understand and the information is jumbled on top of each other. The reason is often by giving too much information, or not enough explanations (see Figure 2.3). The experienced user will probably not have any problems while an inexperienced one will have some difficulties.
Figure 2.3, HMI’s which are hard to interpret.
Web based or stand-alone HMI
The SCADA host-system can be either a stand-alone program, developed in a certain HMI-software, or a web based system. A certain PLC-driver is used to read the information correctly from the power station. If industrial CPU – touchscreens were to be used they are sometimes joined with a HMI pro-gramming software.
Standalone HMI
HMI development software includes the driver needed to read the PLC signals which make the pro-graming easier. There are several softwares available to use and most of them have included graphic options to visualize different systems. In table 2.3 a few HMI software development suites are shown along with a few built-in applications. Everyone has some sort of security feature the programmer is able to adjust in the development of the HMI. Most have a multilingual feature making the program easy to switch languages when used which is a desired possibility if the PCM-engine is to be sold on a broader market. All the softwares have graphics and icons built-in and some have extra libraries where downloads of more are possible. Most are also able to load pictures and illustrations into the program.
HMI software Multilingual use Data logging Built-in graphics Security
Citect CitectHMI
Yes N/A Yes Security features available Beijer electronics
iX
Yes Built-in database Yes Password and other security features
Mitsubishi MX4
N/A N/A Yes Security features available Simatic (Siemens)
WinCC flexible
Yes Database Yes Adjustable access protection
Table 2.3, List of HMI development software.
Probably all of the programs have some sort of data logging feature, however they are not always defined in detail. Some software also includes a browser feature, the possibility to design a web based interface communicating with a on-site HMI.
Web based
3. Synthesis
The process of designing the graphical HMI and the modules are shown in figures, texts and drawings as well a detailed insight in the actual process.
3.1 HMI
The controls and supervision of the PCM-engine is run by a SCADA host system of either a program or web-based version. These are shown by a HMI which lets the user of the system see the necessary data and gives the possibility to exercise control over it. This without giving unnecessary extra infor-mation while at the same time giving enough inforinfor-mation. There should also be an ergonomic view to the supervisory system, making it easy to find the information needed for a specific moment.
The HMI should be made in three different system-sizes. One for the user who only wants to see data and it should only allow an emergency stop signal to the system. The second level should be for the actual operator of the device who can tweak some necessary numbers and control the flow of the de-vice. Thirdly a manual test system should be available where all possible outputs/inputs to the system are available for view and editing, this should however only be able to use on-site in case something unexpected happens.
3.1.1 HMI input/output signals
A table was drawn showing what signals the HMI should be able to edit, see table 3.1. Firstly an emergency stop signal is desired, to be able to manually shut down the device. Such a signal could be made in several ways, by controlling the different pumps or by controlling the valves; however that might lead to an increased pressure in the pipes if the pumps are still operating.
Signals editable by HMI Meaning Output from HMI
Emergency stop Stop system Set Water and Oil pumps RPM to 0
Water pump 1 output RPM of Water pump 1 Set RPM-value for Water circulation pump 1 Water pump 2 output RPM of Water pump 2 Set RPM-value for Water circulation pump 2 Cycle progress Point when switching
Heat-ing/Cooling water
Set switch value to "Second derivate of mean Energy produced"
Cycle time Time between switches Set time run between switches (changes Cycle progress)
System check carried out Latest date of system check Set date: Latest maintenance date Part replacing Date of replacement Set date: Part update
Number of Energy Cells Number of energy cells -Water valves Open/ close the water
valves manually
Set Water valves to Open/Closed
Table 3.1, Table over the signals possibly desired to be editable by the HMI.
The rest of the Signals in the table refer to maintenance issues. A simple way for everyone using the product to know when the last system check was done as well as when each piece was replaced will give a more correct life-span of the device. The number of energy cells should also be an editable variable if the PCM-engine is built module-based. This variable will also help with calculations such as how much energy per Energy cell is produced. For a manual test simulation the water valves func-tionality must be able to be tested, therefore an output should be applied to each of the valves from the HMI.
Furthermore a second table was drawn up showing what signals are transferred into the SCADA host system and the HMI shows see table 3.2. Needed calculations could be made by the host system to use the signals to create new usable data.
Data available to the HMI Meaning Is based on
Number of Cycles Number of cycles run by the
system Number of times valve WV1-1 is opened
Energy produced Net energy generated Difference of temperatures before and after EC, and flow rate of water
Cycle progress Switch heating/cooling water Derivate of mean Energy produced Cycle time Total time to execute one
cycle
Time run between WV1-1 is opened and closed and opened again
Losses in system Energy/Heat losses in system Difference between Input energy (Heat source/ sink Input/Output) and Energy produced Latest system check Date of last system
mainte-nance
Input of Latest maintenance date
Parts usage Number of cycles part is used Input of Part update and Number of cycles Warning Detail nearing critical range Sensor values compared to allowed Oil temperatures Temperature in Hydraulic
system, compared to max Hydraulic temperature sensor 1-3 Oil flow Flow rate of Hydraulic oil Hydraulic flow meter
Oil pump output RPM of Hydraulic oil pump, compared to max
Hydraulic pump
Oil pressure in system Hydraulic pressure Hydraulic pressure sensors 1-7 Water temperatures Temperature in water-system,
compared to desired
Water temperature sensors 1-8 Water valves Positioning of valves Water valves 1-1 to 2-2
Water flow Flow rate of Water (warm), compared to max
Water flow meter 1 Water flow Flow rate of Water (cold),
compared to max
Water flow meter 2 Water pump 1 output RPM of Water pump 1,
com-pared to max Water circulation pump 1 Water pump 2 output RPM of Water pump 2,
com-pared to max
Water circulation pump 2
Table 3.2, Different signals received by the HMI.
The three pumps in the system are both input as to show what RPM they are currently running at and also input as to set a new value. The Water valves, as well, are inputs from the HMI. While the rest of the table shows different signals from the system.
3.1.2 Control unit specification
To control the PCM-engine a control unit is used, along with different modules to perform the desired functions.
PLC
A Programmable logic controller is used to interpret the signals sent from various sensors. Since the I/O used number no more than 21 inputs to the PLC and 11 outputs, a PLC with a sufficient number of integrated I/O is chosen. There are several available devices which are able to service said amount, the Mitsubishi FX3UC 64MT, however has a Ethernet module which is desired due to its easy com-munication with a receiving computer.
One of the aforementioned ethernet modules, FX3U-ENET will be added to the assembly as will an appropriate number of A/D converters. Exclusively analog current loops will be used in the system, because of the systems size and the small number of I/O.
Monitoring
Since most of the monitoring will be done off-site, an industrial HMI display containing a small pro-cessor is placed in the device (Mitsubishi [17] has several options for example), connected to the PLC via its ethernet cable is used as on-site monitor. Alternatively a laptop could be used to simply plug in via the same ethernet cable instead of using a stationary solution.
The device is connected to a modem or to the facility’s internet network to enable off-site monitoring. This demands a firewall to be applied to the system as it otherwise will be vulnerable to intrusion.
3.1.3 Sensor specification
The PCM-engine uses variable sensors and signals to and from devices in the system to control the same as well as to maintain surveillance. The sensors need to be chosen according to the signals used in the specific case and the conditions of its placing. Three companies are at the moment in contact with Exencotech and therefore their solutions are preferable. They are Armatec when sensors for wa-ter are needed, Hydac for different hydraulic solutions and Jumo when wawa-ter temperature sensors are to be looked at.
Water Valves
Eight water valves will be used to switch the water route to the Energy cells in the two different phases. Since there are two equal systems differing only by its heat exchangers temperature there are four valves on each phase. The first two valves control the water, after it has passed through the water pump in its system, guiding it to one of the two phases. The two left are controlling the return of the water, guiding it to the same heat exchanger.
Water flow meters
Armatec [18] are also a reseller of water flow meters, and have two typesof interest, one measuring by ultrasound, the other by magnetic induction. Water flow meters are typically sensitive to turbu-lence in the water, which leads to a needed length of non-bent pipe before and/or after the device. The ultrasound meter does only need a straight of three times the pipe dimension (DN) while the inductive sensor needs five times DN before and twice DN after. The ultrasound flow meter however cost close to 20 000 SEK while the magnetic inductive almost 13 000 SEK, both with necessary accessories. The magnetic inductive sensor is chosen due to its substantially lower cost. The model chosen is AT 7185 with a pipe dimension of 65 mm. A signal converter is needed and the appropriate one is a MAG 5000. This transmits the analog 4-20mA signal desired.
Water thermometers
The measurement of the water temperature is used both as a control of the system as not to overheat, but also to calculate the output energy and losses in the system. There are two measurement locations positioned on the waste water entering the heat exchangers, one on each inlet and one on each outlet. They are also placed where the water enters the energy cells and right after its exit of the aforemen-tioned. These two will be able to calculate the energy taken from the water in the energy cell, in other words, the energy output. The thermometers positioned outside the heat exchangers will perform a similar calculation but also subtract the energy cells energy output, giving the systems heat losses. Jumo [19] has several solutions to measure temperature in different systems, a thermocoupler is chosen with a mineral-insulation. The thermocoupler is chosen with a siliconized compensating cable which has the most appropriate temperature range. For the same reasons the measuring insert type Fe-Con version is picked. Since there are no specific demands to the cable one is chosen which is an in-stock version. The standard compensating cable ending is also chosen along with its length. The products name is: 90.1221/32-1042-1.5-100-11-2500. To connect the thermocoupler to the system a pipe fitting is used, 90.9725, model: 00049701.
To this a transmitter is fitted which transforms the signal to an analog 4-20mA signal. This is also purchased from Jumo and is named: dTrans T01/T01T, model: 707010.
Hydraulic flow meter
To measure the flow rate of the hydraulic oil a flow rate transmitter from Hydac [20] is chosen of model EVS 3100-1. The housing is chosen for oil which defines it to be made of aluminum. The trans-mitter has an analog output and appropriate conditional specifications. The measuring range is chosen to be able to manage between 6-60 liters/min. There are two possible electrical connections, ZBE02 and ZBE03 and given that a higher use of the same product will increase an eventual discount this is chosen together with the two other hydraulic components.
Hydraulic thermometers
Hydraulic pressure sensors
The hydraulic pressures are supervised by sensors of the same brand. The model chosen is HDA 4746-A-600. The same mechanical connection is chosen as in the aforementioned thermometers as well as the pin connections of its electrical output. The maximum pressure the sensor is able to with-stand is 600 bar. The possible electrical connections are ZBE01, 02, 03 and 06. This will make it impossible to order the same connection for the three separate applications and either two applications ZB03 or 06 can be ordered along with another version. This should be decided in a discussion with Hydac.
3.1.4 Concept generating
A small concept generation was made, resulting in two different types of HMIs. The first is a system which is system-oriented, meaning it shows a general system at first glance while giving the user a possibility of exploring the different subsystems more closely by clicking on them or a tab with its name. The second is object-oriented, showing a similar system overview while giving the operator the option to access each part more closely instead of the subsystems.
Concept 1, System-oriented design
The system-oriented design shows a general view, very simplified, over the entire system at a normal start-up (see Figure 3.1). There is also a menu-bar at the windows bottom, showing different tabs. The tabs are shortcuts to the various sub-systems which are also available when clicking on the same
Figure 3.1, View of start-screen of the first HMI-concept.
Figure 3.2, Entered subsystems, to the left the water circulation system, to the right the energy cells.
When accessing one of the subsystems the rest of the subsystems are hidden and eventual sensors and information are displayed instead, see figure 3.2. The hiding of other systems and showing of relevant sensors for the chosen sub-system will give a cleaner and more ergonomic view of the work area. The information shown above the menu-bar is non-editable data while the data on the bar are for control-ling the system and edit values.
Concept 2, Object-oriented design
The second concept is more detailed showing specific objects in the device, see figure 3.3. This will give a greater understanding of the product if the user is less orientated. At its bottom there is a menu-bar like in the first concept, however this is just a menu and contains no tabs which makes it possible to place these anywhere in the work area.
Figure 3.3, Schematic view of the system in the second concept.
Figure 3.4, Objects chosen for detailed information in the second concept, to the left a system control menu and to the right details of the energy cells
This view of the systems objects can be more specific than the sub-system view in the first concept, while it perhaps loses some of the overview the first concept offers.
3.1.5 Evaluation and choice of concepts
After a review of the first draft of the two concepts with co-workers at Exencotech, concept one was preferable due to it simplifying the system to an easily understandable level, although a mix of the two might be an alternative. When a subsystem level is reached, certain important objects could be made available to give further information.
A certain tab showing data from several different sensors at once may be an interesting option. The data could be shown in graphs or tables, based on what sensors are chosen to view. This could result in a personal (for the operator) saving of settings, to allow several operators to use the same surveil-lance system with private settings. The data-tab should also be able to show both current as well as historical data.
The logotype of Exencotech and that of the company purchasing the product should be visible. The Energy output and the Heat sink/source temperatures should also be visible at most times to give the owner of the product a constant status of the output levels.
3.1.6 Development of final concept
The concept chosen is further developed and decided in detail. The selected system will be pro-grammed in a HMI-software as opposed to an entirely web based one.
HMI data
As there are different solutions as how to supervise the system a HMI with three different levels are constructed. The first just for observation and emergency stops, this would be used by the buyer of the product allowing them to see the use of the product. The surveillance will be run in the second level where an operator will be able to use a larger depth of data. The third level will be a test-system where, on-site, an operator will be able to control the different systems without automatic control. As this system is run a “No-edit-mode” will be sent to other HMI.
Observer
The data shown in this mode will be a general system overview, including eventual warnings. A tab showing the energy cells current and mean output, heat source/sink, cycle time, energy losses in the system and the energy cells current phase. The water circulation system will show the different peratures, water flows and the water pumps output. A tab with the hydraulic data will show the tem-peratures, pressures and flow rates of the oil as well as the hydraulic oil pumps output.
Off-site operator
The operators interface will show all the information of the observer as well as a tab showing mainte-nance issues such as maintemainte-nance dates, maintemainte-nance reports and number of cycles run by the system. A tab showing different graphs and tables of the measured data will be available. Seven different graphs or tables that can be viewed in the HMI are shown in Table 3.3. The operator will be able to choose a number of them to view at the same time.
Graphs/Tables
Speed of water and oil pumps
Water temperatures in the system over time The energy cells output energy per phase over time The energy cells output energy in current phase Oil pressures over time
Oil temperatures in the system over time
Output performance, for billing and charging of customers. Various signals close to alarm values, shown beside alarm value
Table 3.3, List of graphs and tables the “data“ tab will be able to show. Manual, on-site test system
The manual test system stationed at the power station will be able to use all the signals shown in Table 3.2. This to test the system and its parts while providing the ability to exercise a more specific sys-tem control. This in a test-syssys-tem tab. All data from the other modes are also available in this as well. The manual system will also make the operator on site able to add maintenance reports which will be available to the off-site operator.
Fonts chosen
The font chosen is a sans-serif easily read on a screen, either Calibri or Verdana as both are common and should be included in a HMI development software. The size will be 18 for headings, and there will only be one size, and 12 for the text body. Any headlines will be black, the text body gray see
Table 3.4. Any data which is deemed as an acceptable value will be written with a green color, while
for an alarm value a red color will be used.
Coloring
Hex RGB Detail
#E3DDD2 227,221,210 General system #FECA78 254,202,120 Energy cells
#AFDFE4 175,223,228 Water circulation system #B29AC3 178,154,195 Hydraulic system
#C2B59B 194,181,155 Maintenance #C69C6D 198,156,109 Test system #93E597 #E67CSE 147,229,151 230,124,94
Data graphs/Tables - green Data graphs/Tables - red #006837 0,104,55 Green texts; approved values #C1272D 193,39,45 Red texts; alarm values #333333 51,51,51 Text body
Table 3.4, Hex and RGB colors of the HMI.
There should be different coloring of heated and the cooled pipes and the different pressures of the hydraulic side should also be shown this way.
Icons
There are symbols for various parts of the system included in the HMI-development software. These could be used or a simplified schematic view as presented in section 3.1.4.
Screen resolution
The HMI should be optimized for a screen resolution of 800 x 600 pixels. Though most screens today have a better resolution than this the possibility of a smaller screen added to the device makes this a preferable ratio.
Final design of HMI
Figure 3.5, The system data tab shown, where desired output will be visible.
The menubar is moved to the top of the screen (see Figure 3.6) where it is more expected to be which will further ease the usage of the HMI. Since there is a possibility that one with a lower understanding of the system is using the observer mode it is decided to add scales to the sensors to simplify the read-ings (see right in Figure 3.6).
During the work with the HMI, both Industriautomation and Fortum were consulted about the be interface which to them seemed both userfriendly and possible to design. However the contact at Industriautomation pointed out the importance of stripping the unneccesary details for the operator continuingly running the system. The “System data” tab is due to this designed to give the operator an own selection of what data to view and being able to save it. The surviellance options able to view in this tab might need further evaluation, when running in a prototype to be optimized.
3.2 Physical design of system
3.2.1 System view
The system this project set out to design was chosen, in discussions with coworkers at Exencotech to be split into a number of modules, see list below. These modules will be separate from each other and can be assembled in different ways and numbers. The water circulation modules and the hydraulic modules will be made to fit different assemblies of the energy cell module. For example, one 100kW product could include two 50kW Energy cell modules, while a 0,5MW product would include 10 modules of the same capacity. Each energy cell has a cylindrical shape and weighs about 30-35kg (which can change dramatically if redesigned and optimized) and measures 80cm in length and 15cm in diameter.
EC-module, including:
Option 1 – ca: 16-30 x Energy cells (about 5-10kW) Option 2 – 144 x Energy cells (about 50 kW)
Piping to interface
Water circulation system module, including:
1 x Water pump 1 x Heat exchanger Piping to interface
Water circulation system - cascade interface module, including:
1 x Water pump Piping to interface
Hydraulic system module, including:
1 x Hydraulic pump 1 x Hydraulic motor 1 x Hydraulic cooler 1 x Pressure transformer 1 x Accumulator 1 x Generator Piping to interface
Electrical system module, including:
PLC-system – inside a cabinet
3.2.2 Concept generating
To find a solution as fitting as possible several brainstorming sessions were made on the energy cell module which is the module which is most likely to save space and weight. It is also most likely the part which would want and need maintenance.
Concept generating by Matrix
First a method called Matrix generating is used to give a large number of possible ways to position the energy cells relative each other. This method is based on a matrix where both the columns and the rows are marked with a characteristic. In this example, the rows are marked with “Number of energy cells in group” while the columns have “Position relative next energy cell”. These are then used to fill the matrix with the appropriate concept (see Figure 3.7).
Figure 3.7, The result of the matrix generating process. Brainstorming of different concepts
Figure 3.8, Sketches of the smaller module concepts, from left to right, a) - e).
The first concept in the group of smaller modules is based on the positioning of the energy cells in a ring formation (see a) in figure 3.8) which would allow the heating / cooling water to enter all the units in this cluster at exactly the same time. One idea is to hang the energy cells in wires from the ceiling (see b) in figure 3.8) which would minimize the structures built to hold the cells. A third con-cept is to place the energy cells vertically in a small rack (see c) in figure 3.8). The last two concon-cepts of this category is to place the energy cells onto a wall (see e) in figure 3.8) where the energy cells are hung horizontally on its two sides, a similar concept with the same basic principle, differing in the way the energy cells are fastened (see d) in figure 3.8) . They are grouped together as a pack and this unit is then hung on the wall.
Figure 3.9, Sketches of the larger module concepts, from left to right, a) - d).
Choice of concepts with most potential
Three concepts were chosen as the ones with the most potential and were further developed.
The Wall
Figure 3.10, The matrix generated concept illustrated in the wall (and wardrobe) concepts.
This concept consists of a smaller sized module of energy cells, of somewhere between 16-24 pieces (see Figure 3.10). The module is built on a square base, with a “wall” placed onto it. The wall is an assembly of beams with fastenings for the cells. Each wall would have its own base and would give the concept a great variety in positioning the different parts. This however leads to a larger volume needed for the module than other concepts. A number of pros and cons for the concept is listed below.
Pros Cons
Flexible positioning Uses more space than other concepts
Flexible control of system Larger quantities of piping/cable wiring needed Larger quantities of fewer parts
Table 3.5, List of pros and cons. The Shelf
Figure 3.11, The shelf concept illustrated from the matrix concept generation.
Pros Cons
Lesser amount of piping Difficult placing of piping to ease maintenance Relatively compact system High amount of large forces on structure
Table 3.6, List of pros and cons. The Wardrobe
The final concept of the chosen three also consists of a “wall” (see Figure 3.10), however, this is not placed on an individual base but rather hung in a larger construction. These walls could then be lifted out of the “wardrobe” and placed in a better position to ease maintenance and transport. The system would consist of several smaller racks which together would be 144 energy cells. A number of pros and cons for the concept is listed below..
Pros Cons
Lesser amount of piping Difficult placing of piping to ease maintenance Relatively compact system High amount of large forces on structure Relatively easy maintenance
Table 3.7, List of pros and cons.
3.2.3 Choice of concept
To make a qualified choice of which concept to use for further development a Decision making matrix is used. To create this a House of Quality is drawn up.
House of Quality
One of the parts in the Quality Function Deployment method is a table called House of Quality which when executed sets appropriate values to different characteristics in the product. Several demands from the list of specifications for the unit (see list below) was added to the House of Quality and also a number of characteristics set to ensure that the demands were able to be fulfilled. A relation-ship value was then added between the demands and the characteristics as to how strong its influence would be over the demand (see Appendix E). When gathered together these values defines the score of the different characteristics concerning the project, which can be used as a base for a decision making matrix.
Accessibility
• Easy access to desired parts • Ergonomic accessibility • Easy to locate desired part
• Few motions needed for access of desired part • Easy to understand how to free/fasten desired part • Easy to free/fasten desired part
• Allow good fastening positions of exterior casing • Allow room to open exterior casing
Construction
• Minimal structural fortifications
• Minimum extra details needed to use product • Optimal positioning of the parts relative each other • Minimum of site requirements to install product • Adapted to fit a module based system
Usability / Service
• As little personnel needed as possible for maintenance • As little training needed as possible to access desired parts • Easily assembled
• Easily dismantled
• Parts should be able to recycle
• Parts should be able to strip from each other with simple tools • Safe to use and to perform maintenance on
Decision making matrix
A decision making matrix is drawn up and weighted with the values mentioned. The concept “Wall” is used as a reference and the other concepts are deemed better or worse than this at every characteristic
(see Table 3.8).
Concepts
Name of characteristic Weight Wall, ref. Shelf Wardrobe
(lower) Elevation of center of gravity 2 0 0 0 (minimize) Amount of moving parts 3 0 0 1
(minimize) Amount of parts 7 0 + +
(minimize) Frequency of same parts 2,5 0 -
-Form of frame 14 0 0 +
Aesthetics 0,5 0 -
-Material 8 0 0 0
(lower) Size 6 0 + +
(lower) Weight 14 0 + +
(lower) Operator force needed 8 0 0
-Mechanism ensuring safety 5,5 0 0 0
Space-saving placing of energy cells 7,5 0 + + Space-saving placing of water-system piping 7,5 0 0 + Need for space, outside of the application 7,5 0 -
-(increase) Frame stability 7 0 + +
Sum 100 0 31 41,5
Table 3.8, Decision making matrix where the Wall is reference and the other concepts are deemed bet-ter or worse than it. This is shown by + or - signs.
It is decided that the “Wardrobe” concept is chosen and is further developed in this project.
3.2.4 Concept optimization
When the concept is chosen it is reviewed in more detail. Several areas of the concept need to be evaluated and optimized due to their impact on other parts. The largest area to improve is the extrac-tion of the individual racks from the larger module.
Extraction device concept generating
The preferred objective of the extracting unit is to lift/slide the rack out of the module and being able to transport the rack to a selected spot and last lowering the rack onto a horizontal mounting. This is deemed most easily done by lowering the rack until its bottom part reaches the floor and meets a pair of wheels which leads it sideways until it is horizontally aligned.
Concept generating and grouping
A brainstorming session was made to find different solutions to the extraction of the racks due to mainly the maintenance of the unit. Several concepts were designed and to achieve a greater overview of them they were grouped according to similarity (numbers) and furthermore by way of mounting rack onto extracting unit (L – leaning against module, S – sliding unit into module, EL – extra legs, EW – extra wheels) and way of horizontally align rack (W – wiring to lower rack, LM – linear motion to lower rack, T – tilting rack horizontally).
Concept I, 1.L.W
The first concept consists of a structure, leaning against the energy cell module for support, and sev-eral wires and pulleys which together gives the operator the possibility to extract and lower the rack (in Figure 3.12 shown as an I-beam).
Figure 3.12, shows the workings of concept 1.L.W, where the green parts shows the larger module and the red marks the extracting device.
This concept needs several operator motions to achieve a horizontal alignment of the rack due to the two different wire configurations. One extracts the rack while the other lowers it. The operator also need to hitch and unhitch the different wiring’s manually.
Pros Cons
+ In/Out of module - Easy to make mistakes when using + Up/Down of rack - High amount of wires needed
- Difficult to connect/disconnect wires
Concept II, 2.L
The concept named 2.L is also positioned leaning against the module though it is, contrary to the first concept, not equipped with wiring but instead a similar beam as is holding the rack in the module.
Figure 3.13, the second concept describes a simple solution which only solves half of the problem at hand.
These beams, with the unit fastened, makes it possible to roll the rack out onto them thus making it possible to extract them (see Figure 3.13). However this concept does not make it possible to align the rack horizontally.
Pros Cons
+ In/Out of module - No Up/Down movement of the frame + Simple construction - Wiring still needed to extract frame + Small amount of wiring needed
Table 3.10, List of pros and cons Concept III, 3.S.LM
The first concept to use the sliding function looks similar to the previous (2.L) in appearance though instead of leaning against the module it fits onto a track on top of the module (see Figure 3.14).
Figure 3.14, A concept where the unit slides into the module.
The extraction unit has a corresponding beam equipped with wheels making it possible to slide the unit into the module and thus makes a horizontal rod fit onto the rack. The rack is then fastened to the rod and then follows the unit out when extracted. To position the rack horizontally a linear motion unit is added and thus lowers or raises the rod.
Pros Cons
+ In/Out of module - High moment of force in lifting arm + Up/Down of rack - Expensive solution
+ No wires needed - Difficult to design a simple solution to lower/raise frame
Concept IV, 3.S.W
Figure 3.15, A concept similar to the third but with wiring to lower the rack.
The concept called 3.S.W is similar to 3.S.LM and are therefore grouped together, with the only dif-ference being the way to lower the rack (see Figure 3.15). While the previous concept uses a linear motion this uses a wired configuration to achieve the same.
Pros Cons
+ In/Out of module - High moment of force in lifting arm + Up/Down of rack - Wiring still needed
+ Small amount of wires needed
Table 3.12, List of pros and cons Concept V, 3.S.LM+T
3.S.LM+T uses the same process of extraction as the last two and a modification of 3.S.LM for its lowering motion.
Figure 3.16, The fifth concept is able to swing the rack around a central axis, thus lessening the lowering height othervise needed.
While the lowering of the rack is similar to the latter it also tilts up to 90 degrees. This is needed be-cause of the position of the horizontal rod which is placed at the racks center and then divided onto its top and bottom (see Figure 3.16). This moves the racks center of rotation to its center of mass instead of its connection axis with the extraction unit which makes the linear motion units length half as long.
Pros Cons
+ In/Out of module - Unstable due to its tilting of the frame + Up/Down of rack - Dangerous to use
+ No wires needed - Expensive solution if desired to lower the frame + Simple construction - High moment of force in lifting arm
- Extra detail needed to lower frame onto
Concept VI, 4.EL+S.LM
The sixth concept also uses a sliding function where a beam can slide into the module and the rack can be fastened to it for extraction (see Figure 3.17). Although instead of leaning on the module it has two extra legs which would, if fitted with wheels, be able to transport the rack.
Figure 3.17, This concept uses a third leg and this discards the need of leaning against the module.
To horizontally align the rack it would use three separate linear motion units, one for each leg which would be an expensive solution.
Pros Cons
+ In/Out of module - Unstable due to its height/base ratio + Up/Down of rack - Large size
+ no wires needed - Very expensive solution due to the need of three lifting devices
+ Simple construction
Table 3.14, List of pros and cons Concept VII, 4.EL+S.W
Figure 3.18, The seventh concept is similar to the previous one, though with wiring to lower the unit.
Pros Cons
+ In/Out of module - Unstable due to its height/base ratio + Up/Down of rack - Large size
+ Small amount of wires needed - Wiring still needed + Simple construction
Table 3.15, List of pros and cons Concept VIII, 5.EW.LM/T
Another solution to the extracting of the rack is to use a modified hand pallet truck which would use two vertical beams welded onto it, together with linear motion units to lower the rack (see Figure
3.19).
Figure 3.19, The eight concept which is a modified pallet truck.
Since the unit does not have to use any support from the module, neither does it have to lift from the racks top, it could use a horizontal rod and lift the racks from its center of gravity. Since this is the case it could also be used to simply rotate the rack around the rod.
Pros Cons
+ In/Out of module - Expensive solution
+ Up/Down of rack - High moment of force in lifting arm
+ No wires needed - Need for space under frame for supportive beam + Easy to understand
Table 3.16, List of pros and cons Concept IX, 5a.EW.W
Figure 3.20, This extraction unit is meant to encircle the module with its wide wheelbase.
To extract the racks the vertical arm is able to fit into several slots, one for each rack. When fitted into appropriate slot it rolls into the module and the rack is fitted onto its wires.
Pros Cons
+ In/Out of module - Wiring still needed
+ Up/Down of rack - Difficult to switch positions for vertical arm + Simple construction - High moment of force in lifting arm
+ Easy to understand - High amount of operator force needed + Only small amount of wires needed - Very large size
Table 3.17, List of pros and cons Concept X, 5b.EW.W
Figure 3.21,
The second of the two similar concepts is called 5b.EW.W and has the same principle except its wheelbase (see Figure 3.21). The former fit around the module while this would fit under it and thus making it smaller and more handy, although not as stable. It will also use up a larger portion of space in the module.
Pros Cons
+ In/Out of module - Wiring still needed
+ Up/Down of rack - The possibility of excentric positioning of lifting device
+ Simple construction - Need for space under frame for supportive beam + Easy to understand - High amount of operator force needed
+ Only small amount of wires needed - Large size
Concept XI, 6.L.LM
The eleventh concept is of the leaning group, although it rolls into the module with its wheels. The beam used for leaning against the module is placed to help the extraction unit from the high moment of force in lifting the rack, spreading it into the modules structure instead (see Figure 3.22).
Figure 3.22
To lower the rack it uses linear motion units (although wiring could also be an option). There is how-ever a high risk of a drawer effect when sliding along the beam.
Pros Cons
+ In/Out of module - Difficulties in designing a simple solution to lower/ raise frame
+ Up/Down of rack - Unstable + No wires needed - Large size
- High moment of force in lifting arm - High amount of operator force needed - Expensive solution
Table 3.19, List of pros and cons Concept XII, 7.L.LM
The last concept is based on bearings with a slit down one side, which are fitted onto the rack (see
Figure 3.23).
Figure 3.23
