Paper type: Case study Pages: 12 (2757 words)
Case Study 40167162 Mechatronics STD3022Contents An Overview Of The Company Concerned An Overview Of The Production Process ” WASTE MANAGEMENT An Overview Of The Production Process ” GASIFICATION Technical Aspects of the Process Technical Aspects of the Process Proposed Development of Particular Control SituationAn Overview Of The Company ConcernedMy study involves the work of the international company BOUYGES CONSTRUCTION. Currently in Belfast they are helping to construct a new waste management solution in the form of a gasification plant. This plant will use household and industrial waste as an input, the output will be electricity.
Bouygues Construction is a global company working in construction, with projects in over than 80 countries. It designs, builds and manages projects in the sectors of building, infrastructure and industry.Bouygues Construction sees innovation as its primary source of added value: this is Shared Innovation that benefits its customers at the same time as improving its productivity and the working conditions of its 47,350 employees. In 2017, Bouygues Construction generated sales of ‚11.
7 billion. Bouygues Energies & Services will be responsible for the engineering, procurement and construction of a 15 MWe facility, and will then carry out operation and maintenance for 17 years. The waste -to -energy power plant will be the largest in the island of Ireland.Jean -Christophe Perraud , CEO of Bouygues Energies & Services, said: This new contract follows on the contract that we signed in February for the 10 MWe waste -to -energy gasification plant in Hoddesdon, England. It confirms Bouygues Energies & Services’ capacity to deliver a large, complex industrial project in the energy infrastructure sector. The new facility will go a long way towards helping Northern Ireland achieve its annual targets for recycling and generating energy from renewable sources. A graphic showing the plant when construction is completed. The gasification plant will have a capacity of 60 MWt . When converted by two steam turbine generators, this will generate 15 MWe of power. Net annual green electricity exported to the grid will be 100 GWh. A neighbouring Bombardier Aerospace manufacturing plant will be the principal user.The waste -to -energy facility will contribute to treating more than 150,000 tonnes of feedstock derived from local commercial and industrial waste and will enable Northern Ireland to save 50,000 tonnes of carbon per year.Construction works, which will involve 200 people, began in January 2016. The operation and maintenance contract will then lead to the creation of 20 local full -time jobs.An Overview Of The Production Process ” WASTE MANAGEMENT To begin with, I have researched the process that is used to deal with the waste used as the input material of the gasification plant. As soon as a consumer places waste in their bin, the waste goes through several stages before reaching the gasification plant.CollectionThe functional element of collection includes not only the gathering of solid waste and recyclable materials, but also the transport of these materials, after collection, to the location where the collection vehicle is emptied. This location may be a materials processing facility, a transfer station or a landfill disposal site.Waste handling and separation, storage and processing at the sourceWaste handling and separation involves processes associated with waste management until the waste is placed in storage containers for collection. Handling also involves the movement of loaded containers to the point of collection. Separating different types of waste components is an important step in the handling and storage of waste at the source.Segregation and processing and transformation of solid wastesThe types of means and facilities that are now used for the recovery of waste materials that have been separated at the source include kerbside collection, drop -off and buy -back centres. The separation and processing of wastes that have been separated at the source and the separation mixed waste usually occurs at a materials recovery facility, transfer stations, combustion facilities and treatment plants. DisposalToday, the disposal of wastes by land filling or land spreading is the ultimate fate of the majority of solid waste, whether they are residential wastes collected and transported directly to a landfill site, residual materials from materials recovery facilities (MRFs), residue from the combustion of solid waste, compost, or other substances from various solid waste processing facilities. A modern sanitary landfill is not a dump, it is an engineered facility used for disposing of solid wastes on land without creating nuisances or hazards to public health or safety.ReusingIn the recent years environmental organizations, such as aFreecycle Network, have been gaining popularity for their online reuse networks. These networks provide a worldwide online registry of unwanted items that would otherwise be thrown away, for individuals and non -profits to reuse or recycle. This free Internet -based service reduces landfill pollution and promotes a gift economy. Energy generationMunicipal solid waste can be used to generate energy. Several technologies have been developed that make the processing of waste for energy generation cleaner and more economical, including landfill gas capture, combustion and gasification . My study deals with the process of gasification and the smaller processes within this.An Overview Of The Production Process ” GASIFICATION The gasification plant is where I am basing the grounds for my project. Gasification is the process that uses waste and produces energy.The gasification of solid materials is not a new concept -gasification first occurred in the late 1700s and early 1800s to produce tar. The types of gasification technologies which are used today have largely been developed over the last 20 years. Gasification is an Advanced Thermal Treatment technology that is characterised by the partial oxidation of the feed stock. Oxygen is added, but not in sufficient quantities to allow the substance to be completely oxidised and full combustion to occur. The partial combustion results in the production of ‘Syngas ‘ which can be used to substitute natural gas, chemicals, fertilisers, transportation fuels and hydrogen.Gasification is not a commonly used process for waste in the UK, that is why the new plant in Belfast is so interesting. It finds a use with certain biomass fuels, for example wood chips. It is only in recent years that gasification has been commercially applied to the treatment of waste, however, large scale plants have been built and are in operation in Europe, North America and Japan. InputsGasification is focused on treating the biodegradable based materials present in waste (e.g. paper, card, green waste, wood), as well as plastics as they have a high carbon content. For this reason, non -combustible materials and recyclables (typically metals and glass), are normally removed in a pre -treatment stage as they can result in a reduction in the heat available for the process therefore affecting the process and operational efficiency.Depending on the technology used, the input material might require processing and pre – treatment such as drying to remove excess moisture and shredding to reduce the size. It is the preference to treat only pre -processed waste that makes these systems appropriate to be used in a waste management strategy.The Gasification ProcessFollowing preparation, the feedstock will be added into the gasifier, where the organic material is converted by partial oxidation into a mixture of the energy rich synthetic gas or ‘syngas’. This is comprised of carbon monoxide, hydrogen and methane. Typically, the gas generated from gasification will have a net calorific value (NCV) of 4 -10 MJ/Nm3. The other main product produced by gasification is a solid residue of non – combustible materials which contains a relatively low level of carbon. For reference, the calorific value of syngas from gasification is far lower than natural gas, which has a NCV of around 38 MJ/Nm3.The Gasification process is largely exothermic, some energy input may be required to begin and maintain the gasification process. The temperature of the process is important, typically the process will operate between 900 -1100 degrees Celcius with air or oxygen. Gasification with oxygen tends to result in a better quality of gas than gasification with air. The fuel value with air is approximately 4 -6MJ/Nm3 and the fuel value with oxygen is approximately 10 -18 MJ/Nm3, this depends on the calorific value of the feedstock used.An Overview Of The Production Process ” GASIFICATION The Gasification Process Continued..Although the precise details vary according to the details of design, the process normally works by the partial combustion of the material to provide heat which then decomposes what material is left. The four points below show the process elements the feedstock will go through in the gasification reactor: Drying by the addition of heat to remove the water vapour from the feedstock Gasification by the addition of heat to volatilize the organic components and produce the syngas, vaporised tars and solid carbon residue Gasification or combustion of the solid residue and tars, upgrading the syngas Combustion typically completes the process and provides for liberation and recovery of the energy value, this stage is not included where the products have some other use OutputsMost gasifiers produce a glass -like by -product called slag, which is non -hazardous and can be used in roadbed construction and in roofing materials. Syngas also need to be cleaned to remove impurities such as sulphur, mercury, particulates and other trace minerals which can then be used for other chemical processes. The Syngas can then be used to substitute natural gas, chemicals, fertilisers, transportation fuels and hydrogen.A gasifier operates at higher temperatures and pressures than a coal boiler — about 2,600 degrees Fahrenheit (1,427 degrees Celsius) and 1,000 pounds per square inch (6,895 kilopascals), respectively. This causes the coal to undergo different chemical reactions. First, partial oxidation of the coal’s carbon releases heat that helps feed the gasification reactions. The first of these is pyrolysis, which occurs as coal’s volatile matter degrades into several gases, leaving behind char, a charcoal -like substance. Then, reduction reactions transform the remaining carbon in the char to a gaseous mixture known as syngas. Carbon monoxide and hydrogen are the two primary components of syngas. During a process known as gas clean -up, the raw syngas runs through a cooling chamber that can be used to separate the various components. Cleaning can remove harmful impurities, including sulphur, mercury and unconverted carbon. Even carbon dioxide can be pulled out of the gas and either stored underground or used in ammonia or methanol production.That leaves pure hydrogen and carbon monoxide, which can be combusted cleanly in gas turbines to produce electricity. Some power plants also convert the syngas to natural gas by passing the cleaned gas over a nickel catalyst, causing carbon monoxide and carbon dioxide to react with free hydrogen to form methane. This “substitute natural gas” behaves like regular natural gas and can be used to generate electricity or heat homes and businesses such as Bombardier in this case.Technical Aspects of the Process A large aspect of the process that I am looking at is going to be how the waste is transported within the gasification plant.To move large amounts of waste efficiently, the plant uses conveyer belts. There are different types of conveyer belts used within the process. Some are for large quantities of smaller items such as everyday waste and some are used for moving larger items of waste. High Density Polymer Rollers High density polymer rollers are used to move large items and containers primarily on the outside of the plant. Inside the plant it is more typical to find chain powered rollers for moving large amounts of smaller items.The characteristics of high density polymer rollers are: 1. High quality -The roller shell is manufactured from HDP (High Density Polymer) with impact resistant, acid resistant, anti -corrosion and anti – alkali in chemical water. The roller is assembled with double cap bearings 2. They are rigid and have high impact roller performance. Different from the steel roller, these rollers have good impact strength. 3. Excellent waterproof and anti -dust resistance -Seal rings prevent water and dust from entering into the inside of the roller. A special catchment groove utilising centrifugal force keeps the inside of the roller dry in all weather conditions which is key in Northern Ireland! 4. Light weight -A polymer roller can be up to 55% lighter than traditional steel roller. 5. Low maintenance cost -A long service life, no lubrication oil needed, and easy replacement, this reduces maintenance. Size -Tube: 102mm/127mm diameter x 8mm wall thickness. A standard example of a chain powered roller conveyer belt A sketched diagram showing how a magnetic pulley is used to separate metals from the waste used.Technical Aspects of the Process Chain Driven Conveyer BeltsChain -driven powered roller conveyors are the four wheel drive of the roller conveyor world.Whereas the lighter -weight line shaft -drive conveyors can allow individual rollers to slip’ if the load is heavy enough, chain -driven powered roller conveyors are all about power and traction. These rollers cannot slip, making it the application of choice for moving large amounts of waste very appropriate.With chain -drive powered roller conveyors, each roller is bound to its neighbour by a chain -and -sprocket arrangement, terminating in a pair of driver rollers, which also connect to the motor by chain. This arrangement ensures that no roller can slip’ under load, and gives positive drive to all of the rollers on the bed simultaneously.Unlike most conveyors, the motor on chain -drive powered roller conveyors is usually centrally -mounted, as this allows a more even distribution of torque across the roller bed as a whole. It is still possible to create a linked system with this technique, merely requiring that the roller bed be divided into separate sections, each with it’s own drive motor, and the necessary sensors. It is still possible to have bends and loops, but these become increasingly impractical and expensive as weight/size increases. Instead, a right -angle transfer station or turntable can be used to accomplish the same effect. The BeltsConveyor Belt is made with E.P. fabric plies. The top and bottom are provided with abrasion resistant rubber covers to DIN 22102 and BS 409.E.P. Polyester/Polyamide (Nylon) fabric is constructed with synthetic woven fabric, utilising a Polyester fibre for warp and Polyamide fibre for weft.Applications:For conveying heavy and sharp edged goods in bulk such as gravel, crushed stone, limestone, iron pellets, glass and coal, also sand, fertilisers, etc.Conveyor belts are products with an extremely high degree of reliability. The main features of the belts are: Low stretch Excellent duraability High abrasion resistant covers Impervious to humidity and wetness Mildew and rot free High tear resistanceOperating systemsA computer system for on -site monitoring is used by the plant to achieve long life and high reliability of conveyor belt processes by using effective methods for diagnosing their condition. The system is able to find applications in real -time monitoring in the plant, to predict the moment of potential errors and to avoid it. The technology allows for a signal to be sent warning of conditions that could lead to belt failure an area of the process and add -ons can extend data analysis. The system allows the workers to constantly monitor the process and address issues when required. The section I am focusing on will use an operating system to detect the variables included with moving batches of waste from one floor of the plant to another. This will use sensors to gather inputs as to how much material is in one place at one time.For my project, I am focusing on a specific part of the conveyer belt.For part of the gasification process, the waste material is transported along the input conveyer belt and is required to be transported in batches from the ground floor to the basement where the gasification process takes place.To do this, the waste is transferred into a chamber which uses a large vacuum to move batches of the material along the production line. The vacuum uses a pressure sensor to operate; when the chamber is full the vacuum activates and moves batches of waste on to the next step of the gasification process.I believe that by using a turntable and a pressure sensor the process could be improved.This improvement would be more cost effective on a large scale and require less maintenance than a large vacuum. Proposed Development of Particular Control Situation Sketch showing the waste, pressure sensor placement and vacuum Sketch showing waste movement into the vacuum chamber and then down to the gasification level. Here the basis of my idea can be seen. Waste can move on to a rotating platform and change direction. The turntable can be fitted with a pressure sensor to allow even amounts of waste to be transferred.
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