Inert Content Research Articles

The Treatment Effect of Chemical Coagulation Process in South African Brewery Wastewater: Comparison of Polyamine and Aluminum-Chlorohydrate coagulants

An evaluation of a laboratory scale chemical coagulation using aluminium chlorohydrate (1%) and polyamine (1%) coagulants on its effectiveness in the removal of bulk inert pollutant contents such as particulate chemical oxygen demand (COD) and turbidity to obtain clean effluent discharge and most cost-effectively treated effluent using a jar test was conducted in this current study. This study aimed to find the viable inert removal coagulant between the two above-mentioned coagulants in order to achieve zero liquid effluent discharge (ZLED). The preliminary results showed that adding variable dosages of polyamine and 50% aluminium chlorohydrate combined coagulants dosages presented an improved particulate chemical oxygen demand, color, and turbidity removal efficiencies. The ascertained turbidity removal efficiency using the combined coagulation dosage of polyamine–aluminium chlorohydrate (PAC) treatment was 90.50% and 59.36% particulate chemcial oxygen demand removal, as comparable to polyamine alone with particulate chemical oxygen demand removal of 50% and turbidity of 75%. Likewise, an appreciable removal efficacy was observed as the aluminium chlorohydrate treatment alone was for particulate chemical oxygen demand and turbidity was 37% and 54%, respectively. In essence, this study emphasized the knowledge gap of the significant effect of the polymeric polyamine flocculant strength in adopting the combined coagulation dosage method to improve its coagulation efficiency and the high agglomeration on suspended solids, thereby, removing more of the unwanted inert contents from brewery wastewater. To determine zero liquid effluent discharge, this study clearly recommended an integrated treatment approach, microbial fuel cell integrated with a lab scale chemical coagulation technique for efficient non-biodegradable pollutant removal.

Numerical assessment of interchangeability potential for syngas-fueled rotary engine

The syngas-fueled rotary engine can be considered as a promising solution for small–scale decentralized power generation due to high specific power, engine simplicity, smoothness and a low tendency for abnormal combustion. Since the decisive feature of syngas refers to feedstock flexibility, in this study we consider syngas with various compositions, produced from biomass, coal and natural gas, as a primary fuel for rotary engines. It was shown that rotary engine performance, efficiency and emission are mostly affected by the balance between combustion promoters and diluents in the air-syngas mixture. Particularly, high hydrogen concentration and lower inert content result in maximum power, heat release and thermal efficiency for stoichiometric and lean conditions. For the rotary engine with a homogeneous charge of the fuel, the combustion process is characterized by the weak influence of turbulence, while the laminar flame speed is an influential parameter in combustion behavior. The high magnitude of specific fuel consumption makes it difficult for engine operation at lean conditions. Although, the lean mixture cannot provide enough high flame temperature for NOx formation. The CO2 emission is affected by the hydrogen to carbon ratio. The opposite trend is observed between NOx and CO emission pathways due to oxygen availability. The power generation system based on the syngas-fueled rotary engine with syngas produced by not only well-known technology such as gasification or steam reforming but novel concepts (non-catalytic partial oxidation) can provide sustainability to the energy sector and reduce consumption of fossil fuels..

Physico-chemical characterisation and quantification of municipal solid waste in high-altitude Srinagar City of North-Western Himalayas

The present study was conducted in the high-altitude Srinagar City, Kashmir during (2018-2019) for physicochemical characterisation and quantification of MSW. A total of 2,000 kg of MSW sample was analysed for two seasons (winter and summer) with 40 samples (n = 5) for each category. The average generation of MSW was assumed (0.48 kg capita-1 day-1); it was estimated that 868 Mt day-1 of MSW generated with a population of 1.81 million during 2019. The findings of MSW characterisation of all the socio-economic groups showed a high bulk density in winter (490.42 kg m-3) and summer (463.75 kg m-3), respectively. Further, results revealed organic waste 54.30%, followed by 23.75% of inert content, and recyclable waste 16.65%. Chemical characterisation showed 47.45% of moisture content with low calorific value (LCV) of 1,307.50 Kcal kg-1 and the C/N ratio of 23.55. Besides, necessary recommendations with eco-friendly options were proposed for the MSW treatment.

Electrode Microstructure and Electrolyte Conductivity Modifications to Improve Thick Sintered Electrode Rate Capability

Increasing the electrode thickness and/or reducing the inert content in a cell are routes to improve the energy density of lithium-ion batteries (Li-ion battery). Sintered electrodes have been pursued towards achieving both of those routes to increase energy density at the cell level. These electrodes are fabricated by sintering of pure active material pellets and thus do not contain any inert additives such as conductive carbon and polymer binder. The greater thickness of sintered electrodes compared to composite electrodes increases the energy density and areal capacity at the cell level. However, a limitation is that Li-ion transport in thick porous electrodes is restricted and impacts the charge/discharge capacity at high rate/current density.In this work, different approaches to mitigate transport restrictions have been investigated with sintered electrode system. First, electrolytes with different Li+ concentration and conductivity were investigated. The highest conductivity electrolyte had the highest retention of capacity at high cycling rates and was combined with pellets with directional porosity which were fabricated via ice-templating. Ice-templating alone also improved the rate capability of the electrodes in the cells, and the combined system with higher conductivity electrolyte and a directional porosity electrode demonstrated substantive retention of capacity at increasing rates. These results showed limitations of thick battery electrodes, and demonstrate possible design improvements in the context of molecular transport properties.

Thermal Analysis and Kinetic Study of Indian Almond Leaf by Model-Free Methods

ABSTRACT Thermogravimetric analysis of Indian almond leaf was carried out at four different heating rates such as 5°C/min, 10°C/min, 15°C/min and 20°C/min. The kinetic study was performed using model free methods and the kinetic parameters were calculated by Kissinger, Friedman, KAS and FWO models. Thermogravimetric analysis resulted that the Indian almond leaf showed four stages of decomposition. Most of the mass loss occurred at stage II (188–460°C) owing to the simultaneous decomposition of cellulose, hemicellulose, and lignin. The shifting of pyrolysis curve occurred with increase of heating rate due to the limitation of heat transfer. The rate of mass loss decreased while increasing the heating rate due to the presence of more inert content i.e. ash and less volatile matters. The mean activation energy calculated by Kissinger, Friedman, KAS, and FWO showed as 52.67, 45.53, 73.73, and 72.28 kJ/mole. The mean activation energy of different leaves reported by earlier researcher was compared with the activation energy of Indian almond leaf and concluded that it stick to the range of activation energy of reported leaves.

CO2-Tolerant Cryogenic Nitrogen Rejection Schemes: Analysis of Their Performances

In the transition to a sustainable energy future, natural gas is a key player supporting a shift away from coal, where renewables and other nonfossil fuels may not be able to grow sufficiently on their own. The growing importance of natural gas has led to a re-evaluation of the potential of unconventional, stranded, and contaminated gas reserves that were previously considered economically unviable. Among them, nitrogen-rich natural gas feedstocks, which in the past were thought to be a not-so-interesting methane source, are now becoming a considerable fraction of the total treated gas. For this kind of low-quality gases, nitrogen removal is necessary to lower the inert content and to produce a pipeline-quality gas or liquefied natural gas (LNG). Considering the available nitrogen removal technologies, cryogenic nitrogen rejection is nowadays the leading one for large-scale applications, with capacities exceeding 0.5 million standard cubic meters per day (MSCMD), being very flexible regarding the inlet N2 content. Depending on the feed composition, different nitrogen rejection units (NRUs—i.e., the single-, the double-, and the three-column systems) are available for treating inlet gas mixtures. The aim of the present work is to evaluate the performances of different cryogenic nitrogen rejection schemes through energy and exergy analysis. Specifically, single-column and three-column nitrogen rejection schemes have been considered with various natural gas feed compositions, focusing on the range where different nitrogen removal schemes are applicable. The net-equivalent methane analysis accounts for the amount of methane required to supply the overall process energy demands through specific processes assumed as reference. On the other hand, exergy analysis evaluates the exergy efficiency of each process scheme through a thermodynamically rigorous approach, converting energy and material flows into their exergy equivalents. Results prove that the three-column process scheme reaches the highest thermodynamic performances, resulting in the best values of exergy efficiency and equivalent methane requirements with respect to the other configurations. This is mainly due to the lower prefractionation column condenser duty, resulting in a less irreversible heat exchanging process.

The Rhyl Field, Block 113/27b, UK East Irish Sea

Abstract The Rhyl Field is located in the offshore East Irish Sea Basin, approximately 30 km to the west of Barrow-in-Furness. Rhyl is one of the producing gas fields forming the Morecambe Hub development, operated by Spirit Energy. The Rhyl reservoir is the Ormskirk Sandstone Formation of Triassic age which regionally comprises four depositional facies types: aeolian, fluvial, sandflat and playa. The depositional system provides excellent reservoir properties that are impacted by a diagenetic history of authigenic illitization and quartz overgrowths. The northern boundary of the field is located underneath the Fleetwood Dyke Complex, resulting in significant imaging and depth-conversion uncertainty. This has been addressed by dyke mapping and manual depth corrections to seismic processing. The trapping mechanism at the southern boundary of the field is also unclear; the dip-closed structural spill point as mapped at the southern boundary appears shallower than the log-derived gas–water contact. Rhyl gas contains a significant inert content: 37% CO 2 and 7% N 2 . The field's production rate has been limited to approximately 40 MMscfgd by the CO 2 processing limit of the onshore gas terminal. Material balance studies have yielded a satisfactory understanding of connected gas in place, recoverable reserves and dynamic field behaviour.

A numerical study of confined turbulent jets for homogeneous combustion with oxygen enrichment

Homogeneous Combustion (HC) and its variants (MILD, FLOX, CDC etc.) have emerged as attractive techniques to abate NOx emissions. The underlying theory is the arrest of Damköhler number (Da) to values close to unity by intense dilution (internal or external) of the reactant streams. The main research problem addressed in this work is the attainment of HC with enriched oxidizers (XO2>21%). The complex and three-dimensional in-furnace flow is described by breaking it down into a set of canonical flows and using parameters related to the latter. Further, jet-momentum ratio and stagnation length are used to characterize the flow-field and their effect on NOx emissions is explained. Unlike oxidizer-jet momentum, fuel-jet (<5% inert content) momentum is seen to have a nuanced effect on reaction zone homogeneity and NOx emissions; while reactant inlet temperature is seen to have little effect. Stagnation distance is also suggested as a length scaling parameter to describe arrangements with multiple confined turbulent jets. It is shown to perform well for flows under the jets by yielding velocity curves which are independent of chemistry. CO and hydrocarbon emissions are found to be dependent only on equivalence ratio. Volumetric standard deviation of Heat Release Rate is used to quantify the tendency of transition to the conventional mode of combustion due to oxidizer enrichment.

POTENTIAL OF SENSOR-BASED SORTING IN ENHANCED LANDFILL MINING

In landfill mining, simple technologies and processing chains are frequently applied to excavated material in order to extract recyclable metals and high-calorific fractions used in energy recovery. Sensor-based sorting is one way to extract more and better material from a landfill. Two testing series have been performed using state-of-the-art technology to assess the technical feasibility of classifying and sorting landfill material with the aid of near-infrared spectroscopy. Fractions were classified as inert and combustible and sorted by particle sizes ranging from 90-30 mm, from 30-10 mm and from 10-4.5 mm for water content levels of 0 wt% and of 15 wt%, respectively. Additional tests applied different landfill mining materials. Polypropylene (PP), polyethylene (PE) and polyvinyl chloride (PVC) products were produced, using sensor-based sorting, from a mixed fraction of particle sizes ranging from 60-200 mm. Both test series applied air-classified heavy fractions gained from two distinct processing schemes of landfill mining projects in Belgium and in Austria. Results show that the separation and classification of inerts and combustibles is feasible, enriching inert fractions with purities of 97.7 wt% to 99.6 wt% derived from inputs whose inert contents achieved 85.6 to 98.8 wt%. Efficient sorting is a function of the level of pre-processing, water content, relative amounts of adhesive fines, input composition and particle size ranges of the input material. Results from the second test series show that PP, PE, PVC and other materials can be successfully distinguished, achieving correct classification and ejection into respective product fractions of 91.8-99.7 wt%.

Comparison between kinetics of autochthonous marine bacteria in activated sludge and granular sludge systems at different salinity and SRTs

Biological nutrient removal performances and kinetics of autochthonous marine biomass in forms of activated sludge and aerobic granular sludge were investigated under different salinity and sludge retention time (SRT). Both the biomasses, cultivated from a fish-canning wastewater, were subjected to stepwise increases in salinity (+2 gNaCl L−1), from 30 gNaCl L−1 up to 50 gNaCl L−1 with the aim to evaluate the maximum potential in withstanding salinity by the autochthonous marine biomass. Microbial marine species belonging to the genus of Cryomorphaceae and of Rhodobacteraceae were found dominant in both the systems at the maximum salinity tested (50 gNaCl L−1). The organic carbon was removed with a yield of approximately 98%, irrespective of the salinity. Similarly, nitrogen removal occurred via nitritation-denitritation and was not affected by salinity. The ammonium utilization rate and the nitrite utilization rate were approximately of 3.60 mgNH4-N gVSS−1h−1 and 10.0 mgNO2-N gVSS−1h−1, respectively, indicating a high activity of nitrifying and denitrifying bacteria. The granulation process did not provide significant improvements in the nutrients removal process likely due to the stepwise salinity increase strategy. Biomass activity and performances resulted affected by long SRT (27 days) due to salt accumulation within the activated sludge flocs and granules. In contrast, a lower SRT (14 days) favoured the discharge of the granules and flocs with higher inert content, thereby enhancing the biomass renewing.The obtained results demonstrated that the use of autochthonous-halophilic bacteria represents a valuable solution for the treatment of high-strength carbon and nitrogen saline wastewater in a wide range of salinity. Besides, the stepwise increase in salinity and the operation at low SRT enabled high metabolic activity and to avoid excessive accumulation of salt within the biomass aggregates, limiting their physical destructuration due to the increase in loosely-bound exopolymers.

The effect of ultra-low temperature on the flammability limits of a methane/air/diluent mixtures.

Natural gas represents an attractive fuel for industrialized and developing countries seeking an alternative to petroleum. Due to economic and safety considerations, liquefied natural gas (LNG) at cryogenic conditions is preferred for storage and transportation. The main drawback is the poor understanding of the physical and chemical phenomena that occur at the storage conditions of liquid methane, i.e. at ultra-low temperatures around 110 K and, if released, at temperatures below ambient. In this work, a procedure to evaluate the laminar burning velocity, the flammability limit (FL) and the limiting oxygen concentration (LOC) of methane-air-diluent mixtures based on detailed kinetic mechanism at ultra-low temperatures is proposed. The estimation of the FL was obtained with the limiting burning velocity theory. The effects of inert content (extinguishing) and agent (N2, H2O and CO2) on FL were evaluated and compared with data retrieved from the literature. The agreement between experimental observation and model results from 200 K-300 K incentivizes the adoption of the new procedure for further studies of fuel reactivity and safety parameters. Moreover, the proposed procedure may be suitable for the estimation of the safety parameters of complex fuel mixtures whose composition is closer to the actual values of LNG.

Effect of hydrocarbon fractions, N2 and CO2 in feed gas on hydrogen production using sorption enhanced steam reforming: Thermodynamic analysis

H2 yield and purity from sorption enhanced steam reforming (SE-SR) are determined by temperature, S:C ratio in use, and feed gas composition in hydrocarbons, N2 and CO2. Gases with high hydrocarbons composition had the highest H2 yield and purity. The magnitude of sorption enhancement effects compared to conventional steam reforming (C-SR), i.e. increases in H2 yield and purity, and drop in CH4 yield were remarkably insensitive to alkane (C1C3) and CO2 content (0.1–10 vol%), with only N2 content (0.4–70 vol%) having a minor effect. Although the presence of inert (N2) decreases the partial pressure of the reactants which is beneficial in steam reforming, high inert contents increase the energetic cost of operating the reforming plants. The aim of the study is to investigate and demonstrate the effect of actual shale gas composition in the SE-SR process, with varied hydrocarbon fractions, CO2 and N2 in the feedstock.

Discrete ejector control solution design, characterization, and verification in a 5 kW PEMFC system

An ejector primary gas flow control solution based on three solenoid valves is designed, implemented and tested in a 5 kW proton exchange membrane fuel cell (PEMFC) system with ejector-based anode gas recirculation. The robust and cost effective combination of the tested flow control method and a single ejector is shown to achieve adequate anode gas recirculation rate on a wide PEMFC load range.In addition, the effect of anode gas inert content on ejector performance in the 5 kW PEMFC system is studied at varying load and anode pressure levels. Results show that increasing the inert content increases recirculated anode gas mass flow rate but decreases both the molar flow rate and the anode inlet humidity.Finally, the PEMFC power ramp-rate limitations are studied using two fuel supply strategies: 1) advancing fuel supply and venting out extra fuel and 2) not advancing fuel supply but instead using a large anode volume. Results indicate that the power of the present PEMFC system can be ramped from 1 kW to 4.2 kW within few hundred milliseconds using either of these strategies.

Simultaneous improvements in flammability and mechanical toughening of epoxy resins through nano-silica addition

Polymers in transport, and many other engineering applications, are required to be mechanically tough as well as resistant to ignition and flame spread. These demands are often for many polymer types in competition, especially when adding flame retardants. With nano-silica addition, we show that improvements in both properties of a polymer can be achieved simultaneously. In this study, an epoxy resin is evaluated for its flammability and mechanical properties with step wise additions of nano-silica. The fracture toughness was significantly improved. In the single edge notch bending test, the addition of 36% nano-silica particles doubled the toughness and increased the flexure modulus by 50%. Flammability was studied via time to ignition at constant irradiation, and via a UL94 test coupled with mass loss and surface temperature measurements. Modelling for the heat transport and chemical kinetics in Gpyro was done and yielded good agreement with the temperatures measured. Adding up to 36% nano-silica, the time to ignition increased by 38% although a sharp decrease was observed around 24% SiO2 addition. We show that the increased time to ignition is mostly due to a higher thermal diffusivity, increased inert content, as well as a strengthening of the residue outer skin, which acts as a mass barrier for pyrolysate. This outer skin was analysed using a scanning electron microscope coupled with an energy dispersive X-ray spectrometer. We found that in the skin the nano-silica particles agglomerate at the surface forming a strong continuous structure together with the char residue from the epoxy. Improvements in the flammability as seen in the UL94 test were measured with mass loss showing a 30% reduction after 20s, and surface temperatures at the ignited end being up to 75K lower compared to the pure epoxy. Modelling in Gpyro supported the temperature measurements taken. Despite the improvements seen, all samples ignited, failing the test with dripping and showing that the improvements recorded in time to ignition did not fully translate over to the UL94 test. Overall we show that the flammability and toughness of epoxy could be improved simultaneously with nano-silica. Using up to 36% nano-silica, the significant modification of thermal properties could be explored in relation to fire properties for epoxy. Increasing the thermal diffusivity as well as skin formation are the main parameters improving the flammability and show a path for potential improvements in other composites as well.

Self-heating behavior and ignition of shale rock

The combustion of shale, a porous sedimentary rock, has been reported at times in outcrop deposits and mining piles. However, the initiating event of most of these fires is unknown. It could be that, under the right conditions, shale rock undergoes spontaneous exothermic reactions in the presence of oxygen. This work studies experimentally and for the first time the self-heating behavior of shale rock. Because shale has high inert content, novel diagnostics such as mass loss measurements and visual observation of charring are introduced to detect self-heating ignition in respect to other self-heating materials with lower inter content. Using field samples collected from the outcrop at Kimmeridge Bay (UK) and the Frank-Kamenetskii theory of ignition, we determine the effective kinetic parameters for two particle-size distributions of shale. These parameters are then used to upscale the results to geological deposits and mining piles of different thicknesses. We show that for fine particles, with diameter below 2mm, spontaneous ignition is possible for deposits of thickness between 10.7m and 607m at ambient temperatures between −20ᵒC and 44ᵒC. For the same ambient temperature range, the critical thickness is in excess of 30km for deposits made of coarse particles with diameter below 17mm. Our results indicate that shale rock is reactive, with reactivity highly dependent on particle diameter, and that self-ignition is possible for small particles in outcrops, piles or geological deposits accidentally exposed to oxygen.

Definition of validated membrane reactor model for 5 kW power output CHP system for different natural gas compositions

Over the last years, many studies focused on the development of membrane reactors for micro-cogeneration systems based on PEM fuel cells, thanks to its unique feature of separating pure hydrogen. This work deals with (i) the design of a fluidized bed membrane reactor flexible towards different natural gas (NG) qualities and (ii) its integration in PEM based systems of 5 kW power output. Four typical NG compositions from reference European countries have been identified in this study featuring an average condition and three extreme cases. Two different membrane reactor models were developed: a 1D phenomenological model and a quasi-lumped model inside the overall system implemented in Aspen Plus. Results show the importance of taking into account the natural gas composition in the design phase: only assuming the NG with the highest inert content as base case, the target electric efficiency of 39% can be reached for any other case.

Beneficiation of an Indian non-coking coal by column flotation

Beneficiation of non-coking coal is gaining ground in India. It not only reduces the volume of inert content to be transported to the power plant and also lowers the wear in the boiler houses. For special applications such as the fuel for integrated gasification combined cycle plant (IGCC), the ash content in the coal should preferably be below 15 %. Indian coals are characterized by high inter-grown ash content mainly due to ‘drift origin’ of Gondwana formation in Permian age. This warrants fine grinding of non-coking coal in order to liberate the ash forming minerals from coal macerals. A non-coking coal sample of vitrinite type from India was ground to 44 µm (d80) and subjected to column flotation to improve its quality. The non-coking coal analyzing 34.6 % ash, 26.2 % volatile matter, 1.3 % moisture and 37.9 % fixed carbon could be upgraded to a concentrate/froth of 14.83 % ash at 72.18 % yield by optimizing collector and frother dosages and flotation column operating parameters, namely, froth depth, superficial feed velocity and superficial air velocity. The concentrate produced by this process is suitable as fuel for IGCC in coal-to-electricity route.

Potentials of cooled EGR and water injection for knock resistance and fuel consumption improvements of gasoline engines

It is well known that the downsizing philosophy allows the improvement of the brake specific fuel consumption (BSFC) at part load operation for spark ignition (SI) engines. On the other hand, the BSFC is penalized at high load because of the knock occurrence and of further limitations on the turbine inlet temperature (TIT). Knock control forces the adoption of a late combustion phasing, causing a deterioration of the thermodynamic efficiency, while the TIT control requires the enrichment of the air-to-fuel ratio (A/F), with additional BSFC drawbacks.In this work, two promising techniques are investigated by a 1D approach with the aim of improving the fuel economy of a turbocharged SI engine at full load knock-limited operation. The first technique is the recirculation of low-pressure cooled exhaust gas (EGR), while the second is the injection of liquid water at the intake ports. Proper “in-house developed” sub-models are used to describe the turbulence, combustion and knock phenomena.The effects of the above techniques are studied in six operating points at full load and different speeds for various A/F levels and inert content, by varying the EGR rate and water-to-fuel ratio. The presented results highlight that both the solutions involve significant BSFC improvements, especially in the operating conditions at medium engine speeds. In fact, the introduction of inert gas in the cylinder contributes to reduce the knock tendency, resulting in the possibility to advance the combustion phasing and reduce, or even avoid, the mixture over-fuelling. The heat subtracted by the water evaporation enhances the above effects, resulting in an improved fuel economy. However, the BSFC advantages are limited by the maximum allowable in-cylinder pressure, TIT, turbocharger speed, and boost level.The developed numerical procedure is able to take into account the complex interactions among different driving parameters affecting the engine behaviour. It can be hence very useful to define a numerical engine pre-calibration and to realistically predict the EGR- and water injection-related BSFC advantages.

An Explosive Range Model Based on the Gas Composition, Temperature, and Pressure during Air Drilling

Air drilling is low cost and effectively improves the penetration rate and causes minimal damage to liquid-sensitive pay zones. However, there is a potential downhole explosion when combustible gas mixed with drilling fluid reaches the combustible condition. In this paper, based on the underground combustion mechanism, an explosive range calculation model is established. This model couples the state equation and the empirical formula method, which considers the inert gas content, pressure, mixed gas component, and temperature. The result shows that increase of the inert gas content narrows the explosive range, while increase of the gas temperature and pressure improves the explosive range. A case in Chongqing, China, is used to validate the explosive range calculation model.

Minimum Ignition Temperature of layer and cloud dust mixtures

The prevention of dust explosions is still a challenge for the process industry. Ignition, in particular, is a phenomenon that is still not completely understood. As a consequence, safety conditions pertaining to ignition suppression are rarely identified to an adequate level. It is well known that, in general, the ignition attitude of a dust depends on several factors, such as the nature of the chemical, the particle size, moisture content, etc., but there is still a lack of knowledge on the effect of the single variables.This paper has the aim of providing data on the Minimum Ignition Temperatures of dust mixtures obtained from a mixing of a combustible dust (flour, lactose, sucrose, sulphur) and an inert dust (limestone, extinguishing powders) as well as from the mixing of two different combustible dusts. Various mixtures with different weight ratios have been tested in a Godbert Greenwald (GG) furnace and on a hot plate in order to measure the effect of mixture composition on the Minimum Ignition Temperature (MITL) of the layer and on the Minimum Ignition Temperature (MITC) of the cloud. In order to further verify the effects of inert dust particle size, inerts sieved to different size ranges have been tested separately. Generally, both MITL and MITC increase as the inert content is increased. MITC is poorly affected by inert particle size when limestone is used. The MITL of pure flour is higher than the MITL of mixtures containing up to 40% of 32–75 μm of limestone. This was probably due to the behaviour of pure flour during the test, which demonstrated strong tendency to produce char, cracks in the layer and detachment from the hot plate.