The project has focused on the risks of dust explosions and any fire that may arise in various manufacturing processes where metal dust is formed. The work has included studying available statistics to get a better picture of frequency, cause and effect in connection with explosions that occurred, but also to study some real incidents in detail to give examples of events and in some cases also measures taken to reduce the risk of similar events occurring again. In the project, a limited literature review has also been conducted.

Nationally, incidents reported to the Swedish Work Environment Authority have been studied as well as statistics based on the incident reports provided by the Swedish Fire and Rescue Services to the Swedish Civil Contingency Agency (MSB). Internationally, we have mainly studied statistics from the US compiled by CSB (U.S. Chemical Safety and Hazard Investigation Board) and from the database "Combustible Dust Incident Database". Studying metal dust explosions specifically, these constitute about 20-25 % of all explosion incidents. It is also clear that the explosions usually occur in dust extraction systems and associated equipment. In several of the incidents, these have also been associated with some form of manual work in the plant, for example cleaning. In many cases, explosions have also been associated with ignorance, e.g. by lack of control of the equipment. The report gives some examples of this type of incident.

Although Sweden has been spared from fatal accidents related to dust explosions, the international statistics show that this is a very common consequence. During the last 15-year period, CSB statistics show that this in average resulted in 0,3 fatalities per reported metal dust incident. It can also be noted that some very serious accidents have occurred in China within the metal industry caused a large number of fatalities. This indicates that dust explosions in the metal industry can be very violent.

Increased knowledge and exchange of experience between metal working industries could result in risk mitigation measures and improved working procedures and are perhaps the most important measures to reduce the risk of serious explosion incidents. There is also a need for more basic knowledge about the explosion processes for different types of metals in order to ensure that different types of protection systems are dimensioned in a correct manner. Today, it cannot be assumed that this is the case as standards for different protection systems are not always adapted for metal dust.

The report also presents some recommendations that form a basis for minimizing the risks for dust explosions.

The design of explosion mitigation strategies e.g. vent design is mainly based on dust explosioncharacteristics such as the maximum explosion pressure XÇïÓ and the deflagration index n! of dustcloud, which are defined in various standards.The wood dust explosion characteristics can be directly obtained by performing standard tests, and testresults are also available in the literature. However, the parameters for one type of dust may varysubstantially in the literature. For example, the n! value for one wood dust is 11.4 times higher thananother wood dust in Gestis-Dust-Ex database. The reason for such large variation in explosionparameters is due to factors such as material properties, particle size distribution, particle shape, moisturecontent, turbulence level during tests and so on.The objectives of this paper are (i) to carry out dust explosion tests for XÇïÓ and n! for two wood dustswith well-described material parameters such as particle size distribution and moisture content accordingto European standards, (ii) to perform statistical analysis of wood dust explosion characteristics includingXÇïÓ and n! in the literature, (iii) to identify the effects of dust material parameters such as particle sizeand moisture contents on XÇïÓ and n! and (iv) to highlight the variation in XÇïÓ and n! and theimportance of obtaining knowledge about these properties of an individual dust, e.g. via dust explosiontests.

The disposal of digested sewage sludge is becoming a global problem. Hydrothermal carbonization (HTC) combined with the pyrolysis of digested sewage sludge was investigated by using a new conversion route for the exploitation of sewage sludge in energy applications. The thermochemical properties of the material were investigated by using HTC pre-treatments, thermogravimetric analyses, pyrolysis tests in Py-GC/MS and a bench-scale fixed bed reactor at temperatures of 450, 550, and 650 °C. It was found that the thermal decomposition of the hydrothermally treated digested sewage sludge takes place in a two-stage reaction. After pyrolysis, the ash in the sample was oxidized in the O2 atmosphere at 900 °C. Therefore, a new characterization method for determination of the non-oxdized ash content and fixed carbon content was proposed. The result from Py-GC/MS shows that the abundance of aromatic hydrocarbons in pyrolytic vapors present a positive correlation with increased temperature. In the bench-scale experiments, the highest HHV of the organic fraction was obtained at 650 °C as 38.46 MJ/kg. 

Syftet med detta projekt har varit att ge ökad kunskap kring olika förekommande brandrisker och råd om hur dessa kan reduceras med olika åtgärder, primärt baserat på praktiska erfarenheter från genomfört säkerhetsarbete samt uppkomna bränder ute i olika anläggningar. Målet är att de samlade kunskaperna och erfarenheterna kan komma till nytta för hela branschen, övriga berörda intressenter och myndigheter och på sikt ligga till grund för t.ex. framtida branschrekommendationer.

Projektet kan delas in metodmässigt i; statistik, workshoppar samt analys av anläggningsspecifik information.

Analysen av insatsstatistik från Myndigheten för samhällsskydd och beredskap (MSB) pekar på att det inträffar i storleksordningen 60–70 bränder årligen i avfallsanläggningar och att brandorsaken i de flesta fall är självantändning eller okänd anledning. Tittar man på "brand ej i byggnad" med relevanta bränder för avfallsanläggningar så ser man en svagt ökande trend i antal bränder 2012–2015. 

De vanligaste materialfraktionerna som enligt statistik från MSB är kopplade till bränder i avfallsanläggningar är sopor, kompost, fluff, papper, trädgårdsavfall, däckgranulat, annat, skrot, återvinningscontainrar. Även en del av flisbränderna kan vara relaterade till RT-trä.

Från avfallsindustrins sida ansågs bark, returträ, flisat material och GROT (grenar och toppar) kunna ge problem med självuppvärmning. Även krossning av avfall angavs som ett generellt problem av flera deltagare.

Många incidenter och bränder anses bero på felsorterat eller feldeklarerat avfall och kontrollen av inkommande gods är därför väldigt viktig. Det är också viktigt att kommunicera uppströms i leveranskedjan för att öka chanserna att komma tillrätta med problemen. Många deltagare identifierade batterier (speciellt litiumbatterier) som ett växande problem.

Hanteringen av förorenat släckvatten varierar mycket. Man påpekar att samma krav över hela landet vore bra. Man önskar tydligare riktlinjer för släckvattenanalyser, kunskap om vad vattnet kan innehålla och information om reningsmetoder för släckvatten.

Det påpekas att det finns många standarder och normer att förhålla sig till så det vore därför bra att ha en lägsta nivå av krav som bestäms i samarbete med branschen som man kan förhålla sig till och någon form av vägledning från myndigheterna för göra hanteringen mer lik över riket.

Diskussionerna under workshopparna och tillsammans med projektets referensgrupp har lett fram till 33 rekommendationer uppdelade på olika områden. För varje rekommendation ges i rapporten ytterligare förklaringar. Dessa rekommendationer kan ligga till grund för framtida riktlinjer.

The self-heating process in a laboratory scale experiment has been modelled using the Comsol Multiphysics software. In the simulations the gas flow and air movement in the volume and heat diffusion in the bulk were taken into account however only one reaction in the pellets bulk is considered. The input data is found from measurements of the reaction chemistry and the heat transfer properties. It is found that all relevant physics is needed in order to obtain reasonable predictions in particular the heat transfer between the bulk and the gas is important but also condensation and evaporation of moisture.   

Recent pellet stoves perform excellently under type test conditions. In contrast, typical real life emissions show significantly higher values under usual operational conditions. Consequently, type testing procedures may not account for real life stove operation and, thus, do not allow to distinguish between low- and high-tech appliances. The EU-project beReal aimed at the development of a testing method for pellet stoves that reflects real life operations better and to support innovative pellet stoves that perform well under typical operational conditions. Based on an online survey and field observations, an advanced real life testing procedure for pellet stoves was established reflecting real life user behavior, e.g. regarding different load levels and the ignition phase. A field test was designed at the end of the project to demonstrate the applicability and practical relevance. The field test proved that emission values for beReal at the test stand and in the field stay within the same range. A Round Robin test proved the repeatability and reproducibility of the beReal testing procedure. The beReal method can be reproduced with the same statistical variability or performed even better than the type testing method with exception of PM between different laboratories. © 2017, ETA-Florence Renewable Energies. All rights reserved.

For the risk for spontaneous combustion in storage of biomass pellets to be assessed, it is important to know how prone the fuel is to self-heating. There are traditional methods that are used to determine self-heating characteristics of fuels, eg, basket heating tests. The results from basket heating tests indirectly give the reactivity from a series of tests at high temperatures. This paper presents a sensitive screening test procedure for biomass pellets using isothermal calorimetry for direct measurement of the heat production rate at typical bulk storage temperatures. This method can be used to directly compare the reactivity of different batches of biomass pellets. The results could be used, eg, by storage security managers to gain better knowledge of their fuels propensity for self-heating and thereby for safer storage. A large number of tests have been performed to develop the test procedure presented. Different parameters, such as temperature, type of the test sample (powder/crushed or pellets), mass of test sample, and preheating time, have been varied. Furthermore, gas concentrations in the sample ampoule have been measured before and after some tests to study the oxygen consumption and the formation of CO and CO2. Three different types of pellets with different characteristics were tested to assess the variation in behaviour. Based on these tests, a screening test procedure is presented with a test temperature of 60°C, a sample size of 4 g, a 15-minute preheating period at the test temperature, and 24-hour test duration.

In order to assess the risk for spontaneous combustion of biomass pellets during storage it is important to know how prone the fuel is to self-heating, i.e. to determine the reactivity. 

This article presents the results from isothermal calorimetry tests performed on 31 different biomass pellet batches. The purpose of the tests has been to characterize pellets by measuring the reactivity and investigate how the pellet composition influences the heat release rate and thereby the self-heating potential of pellets. 

The results from the tests clearly indicate that there is a significant difference in reactivity between different types of pellets. The tested high reactive pellet batches reached maximum specific heat release rates (HRR_max) of 0.61-1.06 mW/g while pellet batches with low reactivity showed HRR_max of 0.05-0.18 mW/g. The tested batches were primarily ranked based on HRR_max but an alternative ranking based on specific total heat release rate during the test period was also used for comparison. 

The test results also indicate that pine/spruce mix pellets are significantly more reactive than all other types of pellets tested and that pellets consisting of 100 % pine are more reactive than pellets consisting of 100 % spruce. Pellets produced from wine pruning/grape pomace (winery wastes), straw or eucalyptus are not very reactive compared to pellets consisting of pine/spruce. 

The results also show that the reactivity of the pellets can be reduced by either introducing certain kinds of anti-oxidants into the pellets or by extracting lipids from the raw material of pellets.

The ETANKFIRE project is focused on tank fires involving ethanol; the work conductedin this part of the ETANKFIRE project (WP1 and WP2) has been focused on tankfirefighting operations.Two series of fire extinguishing tests in reduced scale have been conducted. Both testseries simulated tank fire conditions by using a large amount of fuel and long preburntimes. The influence of foam application techniques, foam characteristics, and applicationrates have been investigated. Some tests have also included alternative extinguishingmedia such as cellular glass, liquid nitrogen and aqueous vermiculite dispersion (AVD).In total 29 extinguishing tests were conducted in the first test series using a 0,41 m2 firetray and 14 tests were conducted in the second test series using a 3,14 m2 fire tray. Priorto the experimental work a literature review was conducted to gain experience, both fromreal tank fire incidents and from various test and system design standards for the use offoam on water-miscible fuel fires.The results showed the importance of the characteristics of the finished foam. Higherfoam expansion ratios and longer drainage times resulted in significantly improved fireperformance. These improved foam characteristics are dependent on the foam applicationhardware as well as the foam concentrate formulation. To obtain these improvedcharacteristics the foam concentration was increased to 6 % from a nominal value of 3 %On the other hand, the improved foam characteristics allowed the application rate to bereduced by 50 % without compromising extinguishing performance. This shows that theperformance requirements in existing test standards for foam (e.g. UL 162, EN 1568) donot provide an incentive for manufacturers to formulate their foam to handle more severefire conditions, such as a tank fire scenario.The tests also indicated that gentle application of the foam is not guaranteed by the use offoam pourers (Type II discharge outlet according to NFPA 11) as the foam was not ableto flow gently along the tank wall due to high steel temperatures.With respect to alternative media, applying a layer of cellular glass followed by foamapplication made the extinguishing operation even more robust.The overall conclusion is that fighting ethanol tank fires would very likely result in afailure to extinguish if standard firefighting operations are used. However, the test resultsalso indicate important parameters that would improve the possibilities for a successfulextinguishment. Further validation of these results in larger scale could also providepossibilities to improve foam system standards, e.g. NFPA11 and EN 13565-2 forextinguishment of water-miscible fuels as well as test standards for foam concentrates(e.g. UL 162, EN 1568-4).Key words: ethanol, fire extinguishment, fire suppression, tank fire, tactics, foam, foamconcentrate, CAF, liquid nitrogen, vermiculite, cellular glass.