Södra Cell Mönsterås (SCMS) är en betydande producent av pappersmassa som årligen producerar runt 750 000 ton. Vid produktion av pappersmassa så blir bark en biprodukt. Barken barkas av i renseriet och transporteras upp till barkpannan och rökgastorken via transportörsband. SCMS står inför betydande problem med dammbildning när barken byter transportband, särskilt med en höjdskillnad på 5–6 meter. Ett övertryck bildas i kanalen under övergången och alla små partiklar trycks ut och det resulterar i en dammfylld miljö.Syftet med examensarbetet är således att förklara hur dammbildning uppstår och vad det finns för risker med det. Men huvudmålet är att hitta den bästa lösningen för att minska dammbildningen runt transportörerna. Denna undersökning kommer att vara relevant för mer än bara SCMS då detta är ett problem som är vanligt förekommande i olika industrier. Med hjälp av vår forskning så kommer SCMS få en bra överblick över vad det finns för relevanta lösningar och vad det skulle kosta. Uppgiftsbeställningen kan ses i bilaga 1.Både i miljö och arbetssyfte är detta ett problem som måste lösas. Att andas in barkdamm är hälsofarligt och kan även vara cancerframkallande vid vissa trädslag. Mestadels av trädamm som vi andas in kan vår näsa stoppa, men är det nog små dammpartiklar kan de leta sig ner i lungorna.Under forskningen kontaktades relevanta industrier som har eller haft liknande problem. Studenterna kontaktade även kunnigt folk inom detta område och diskuterade olika lösningar på problemet. Resultatet av dessa kontakter var att det finns många som stött på liknande problem men inte exakt likadana, vilket gör att det inte fanns en universell lösning innan undersökningen var slutförd.Undersökningen visade att det finns många olika lösningar för att hantera dammbildningen vid omlastningsstationen på SCMS under barktransportens bandbyte. Många av dessa lösningar hade dock betydande nackdelar, såsom höga tekniska krav, höga kostnader eller för stor potentiell påverkan på processen.Slutligen kom studenterna fram till att den bästa lösningen var att leda bort dammet med en ventilationskanal till en behållare, där vattendysor sprayar ner dammet i avloppet. Denna metod påverkar barken minimalt medan den effektivt avlägsnar dammet. Dessutom var kostnaden för denna lösning rimlig, vilket gör den både säker och ekonomiskt fördelaktig. Slutkommentar från SCMS visas i bilaga 2, denna visar att studenterna har löst uppgiften på ett bra sätt. / Södra Cell Mönsterås (SCMS) is a significant producer of pulp, annually producing around 750,000 tons. In the production of pulp, bark becomes a residual product. The bark is stripped off in the cleaning plant and transported up to the bark boiler and the bark furnace via conveyor belts. SCMS faces significant problems with dust formation when the bark changes conveyor belts, especially with a height difference of 5-6 meters. An overpressure is formed in the channel during the transition, and all small particles are pushed out, resulting in a dusty environment.The purpose of the thesis is thus to explain how dust formation occurs and what risks are associated with it. However, the main goal is to find the best solution to reduce dust formation around the conveyor. This study will be relevant to more than just SCMS as this is a fairly common problem. With the help of our research, SCMS will get a good overview of relevant solutions and their costs.Both environmentally and from a work perspective, this is a problem that must be solved. Inhaling wood dust is hazardous to health and can even be carcinogenic for certain tree species. Most of the wood dust we inhale can be stopped by our nose, but if the dust particles are small enough, they can penetrate into the lungs.During the research, relevant industries that have or have had similar problems were contacted. The students also contacted knowledgeable people in this field and discussed various solutions to the problem. The result of these contacts was that many had encountered similar problems but not exactly the same, which meant that there was no universal solution until the investigation was completed.The investigation resulted in finding many different solutions for managing dust formation at SCMS during bark transport belt changes. However, many of them were found to have significant drawbacks, such as technical requirements, high costs, or too much potential impact on the process.Finally, the students concluded to use the solution where the dust is directed away through a ventilation duct to a container, where water nozzles have been installed to spray the dust down the drain. This solution was one of the solutions that affected the dust the least and effectively removed the dust. It was also reasonably priced for a safe and efficient solution.

Increasing commercial and military aircraft operations in arid environments are increasing the likelihood of sand and dust ingestion. Turbine engines are particularly susceptible to the ingestion of sand and dust, which can erode cold-section components and deposit onto hot-section components. Ultimately, the erosion and deposits will shorten the operational lifespan of these engines and limit their availability thereby increasing maintenance costs and risking safety. Mitigating these risks has become more prevalent in recent years due to increasing combustion temperatures in effort to increase fuel efficiency. Increasing combustion temperatures directly increases deposit formation onto hot-section components. Monitoring deposit formation on existing turbine engine platforms and improving deposit resilience on new designs has been the industry focus for the last two decades. This study focused on statistically modeling the initial onset of microparticle deposits onto an analogous hot-section surface. Generally, as deposits accumulate onto a hot-section surface, the existing deposit formation is more likely to bond with incoming particulate at a faster rate than an exposed bare surface. Predicting the initial deposits onto a bare surface can determine the accelerated deposition rate depending on subsequent particulate impinging onto the surface. To emulate the initial deposits, a HASTELLOY® X test coupon was exposed to 20 μm to 40 μm samples of Arizona Road Test Dust (ARD) at varying loadings and aerosol densities. The Virginia Tech Aerothermal Rig was used for all test scenarios at flow-particle temperatures between 1000°C to 1100°C. Several statistical models were developed as a function of many independent variables, culminating with a final sticking probability (SP) model. Overall, the SP of individual ARD particulate is a primary function of flow-particle temperature and normal impact momentum. Tangential impact momentum of a particle will decrease the SP, while surface temperatures reaching isothermal conditions with the flow will increase SP. However, there are specific cases where lower surface temperatures and high particle temperatures result in a high SP. Particle size was a strong predictor of SP where particles between 10 μm to 19 μm were 5 to 10 times greater than the 19 μm to 40 μm range. Additional studies will be necessary to examine some additional parameters that become more prominent with smaller particle sizes. Ultimately, the intention of the models is to assist turbine engine designers to improve resilience to deposit formation on hot-section components. / PHD / Dust ingestion by propulsion turbine engines can have severe negative implications on the operational safety of an aircraft. Recently, increased air traffic, both military and commercial, in desert regions has caused many aircraft engine designers to improve the resilience to dust ingestion effects. One of the detrimental mechanisms is hot particle deposits in the combustion and exhaust sections. This dissertation evaluates deposit formation using carefully developed high temperature experiments. In general, deposit formation can negatively change flow characteristics inside the engine that can limit available power and safety margins. Likewise, deposits can reduce or stop cooling needed for hot-section parts inside a jet engine. Hot-section components need cooling since the main gas path operation temperatures of a jet engine typically exceed the melting points of common high temperature metals. During dust ingestion events, deposits will initially adhere to a hot metallic or ceramic surface inside the engine. Subsequent deposit accumulation will occur at a faster rate since incoming particles will more readily adhere to existing deposits than to a metallic or ceramic surface. The experimental work in this dissertation focused only on quantifying the initial individual particle deposits on a HASTELLOY®-X surface between 1000°C to 1100°C. Arizona Road Dust was the particulate selected for all testing. The dust has sizes ranging between 10 µm to 40 µm. The sticking probability or the likelihood a particle would deposit per an impact was less than 5% for all tests performed. Particles smaller than 19 µm had a sticking probability up to 5% while larger particles were generally less than 3%. Effectively, this implies that the initial deposits onto a hot engine surface are strongly dependent on the smallest particles. Propulsion turbine engine designers can utilize this information to develop mitigation methods against deposit formation of the smallest particles that are ingested. Ultimately, the research presented in this work is intended to improve operational safety of current and future aircraft.

LD2668 .T4 1966 B75 / Master of Science

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.