Small-scale combustion testing

No differences in flammability characteristics between the 0.1% Cu20-treated and untreated flexible polyurethane foam were observed. These characteristics were examined to assure that the positive effect on toxicity was not contradicted by negative effects on the flammability properties. The flammability characteristics examined were (1) ignitability in three systems (the NIST Cup Furnace Smoke Toxicity method, the Cone Calorimeter, and Lateral Ignition and Flame Spread Test (LIFT)), (2) heat release rates under small-scale (Cone Calorimeter) and medium-scale (furniture calorimeter) conditions, (3) heats of combustion under small-scale (Cone Calorimeter) and medium-scale (furniture calorimeter) conditions, (4) CO/CO2 ratios under small-scale (Cone Calorimeter) and medium-scale (furniture calorimeter) conditions, (5) smoke obscuration (Cone Calorimeter), and (6) rate of flame spread (LIFT). 

To determine the applicability of the process to flue gas from coal combustion, a small scale (0.6 MWg) unit was built and placed into (deration by UOP, hic. at Tampa Electric Company s Big Bend Station in North Ruskin, Florida. The pilot plant was started up in 1974 and operated for approximately 2 years. During this time, six runs were made involving over 13,000 acceptance and regeneration cycles with the same acceptor loading. The test program demonstrated... 

Laboratory experiments using rodents, or the use of gas analysis, tend to be confused by the dominant variable of fuel—air ratio as well as important effects of burning configuration, heat input, equipment design, and toxicity criteria used, ie, death vs incapacitation, time to death, lethal concentration, etc (154,155). Some comparisons of polyurethane foam combustion toxicity with and without phosphoms flame retardants show no consistent positive or negative effect. Moreover, data from small-scale tests have doubtful relevance to real fine ha2ards. 

Flammability. The results of small-scale laboratory tests of plastic foams have been recognized as not predictive of their tme behavior in other fire situations (205). Work aimed at developing tests to evaluate the performance of plastic foams in actual fire situations continues. All plastic foams are combustible, some burning more readily than others when exposed to fire. Some additives (131,135), when added in small quantities to the polymer, markedly improve the behavior of the foam in the presence of small fire sources. Plastic foams must be used properly following the manufacturers recommendations and any appHcable regulations. 

The temperature for methane and butane calculated with the isothermal model is a factor 1.4 times greater than the average temperature measured by Lihou and Maund (1982) in their small-scale tests, although higher local maximum temperatures were measured. In this model, combustion is stoichiometric, thus leading to very high fireball temperatures which, in turn, lead to high radiation emissions. Effective surface emissions measured experimentally were one-half the value calculated from this model, because combustion is not stoichiometric and emissivity is less than unity. 

In running the DIN 53436 method hydrocarbon and hydrogen cyanide has only been determined qualitatively. The cyanide concentration has been determined four times during the 30 minute steady state combustion process. From these experiments the average concentration of emission has been estimated. The other results presented in Table V from DIN 53436 experiments have been measured in similar ways as for the other small scale test methods. It may be observed that the amount of material burnt in each experiment is smaller than in previous test procedures. The results presented are average values of two deteminations of each material. 

NFPA-701 (large and small scale) These tests are sanctioned by the National Fire Protection Association, a volunteer organization of fire protection professionals. Figure 1 illustrates the set up. The vertical alignment of flame and sample allows maximum heat and flammable gases to feed the flame front of the sample, assisting further combustion. 

Detection.—Sulphur in the free state is readily recognisable by its general appearance and characteristics, and especially by its combustion to sulphur dioxide. Both in mixtures and compounds the presence of the element can be demonstrated by heating with charcoal and an alkali carbonate,2 or even better, on a small scale, by heating with an equal bulk of sodium or potassium,3 or with powdered iron 4 in each case some of the sulphur is converted into sulphide, which may be detected by the action of an aqueous extract on mercury or silver, or on sodium nitroprusside the metals are blackened, whilst the nitro-prusside is very sensitive in giving a purple coloration (see p. 62). Alternatively, the solution of the alkali sulphide may be acidified and tests applied for hydrogen sulphide to the vapours evolved on warming. 

Emissions from fireplaces and stoves have been reported in several studies testing furnaces and wood fuel typical for different areas of the world. Wood smoke emissions typical for central Europe were investigated by Schmidl et al. [22, 23]. In these studies, different common European wood types were analysed to derive chemical profiles of wood combustion emissions for various types of wood. An overview of the fuel wood types used in the Alpine countries is given by Kistler et al. [24]. In the above-mentioned emission studies, wood has been burnt in a tiled wood stove [22] and in two automatically and two manually fired appliances [23]. The authors found a high variability for the emissions from small-scale manually fired wood combustion appliances in the performed individual tests. 

In practice, types of burning equipment, rate of burning, temperature and thickness of the fire bed, distribution of ash-forming minerals in the coal, and viscosity of the molten ash may influence ash behavior more than do the laboratory-determined ash fusibility characteristics. The correlation of the laboratory test with the actual utilization of coal is only approximate, due to the relative homogeneity of the laboratory test sample compared to the heterogeneous mixture of ash that occurs when coal is burned. Conditions that exist during the combustion of coal are so complex that they are impossible to duplicate completely in a small-scale laboratory test. Therefore, the test should be considered only as an empirical one, and the data should be considered qualitative and should not be overinterpreted. 

A new small-scale test has been developed which needs only a few g of thermally unstable material, which may be contained in an open cell version of the apparatus if aerobic processes are involved, otherwise in a closed cell apparatus, both with full temperature control and monitoring systems. Such materials may be divided into 2 types, depending on the behaviour of a sample after introduction into adiabatic storage at elevated temperature. The first type, which after attaining the adiabatic temperature shows a steady further increase in temperature in line with Frank-Kamenetski s thermal explosion theory, exhibit thermal combustion (TC) behaviour. In the second type, after adiabatic temperature has been reached, the sample shows a sudden rapid rate of rise, exhibiting autocatalytic (AC) behaviour as chain branching... 

Specifically, the work done at Plant Sweatt examined the applicability of 1x liquid synthetic fuels to a full scale, wall fired utility boiler 1n terms of boiler efficiency and emission characteristics. EPRI sponsored testing with synthetic fuels at other sites Included small scale combustors, a Combustion Engineering wall-fired utility boiler, a Combustion Engineering tangentially-f1red utility boiler, a combustion turbine and diesel piston engines with generally favorable results. 

PANELIST WOLK We also have some questions along those lines and we are planning some additional small-scale combustion work to sort out the behavior of the medium and heavy distillates and blends thereof in the same test apparatus that was used by KVB in the original work, which used two-to-one blend. 

A round robin was organized wherein several teams modeled the fire spread before they were provided with the experimental results (a priori simulations) [101]. Participants were given basic information regarding the layout of the apartment and the types of combustibles present, but they were not provided with small-scale test data (i.e., Cone Calorimeter, thermogravimetric analysis, etc.) to characterize any of the combustibles present in the apartment. Most teams used FDS4, and two teams used CFAST. 

Batt, A.M. Appleyard, P. The mechanism and performance of combustion modified flexible foams in small scale fire tests. J. Fire Sci. 1989, 7, 338-363. 

N0X emissions tend to be higher due to the higher fuel nitrogen levels of coal-derived fuel oils. However, it appears, based on small scale lab tests (2) and limited commercial tests (3), that staged combustion should allow N0X emissions standards for coal-derived fuel oils to be met. One environmental concern that had not been addressed in these tests is the emissions of PNA. This is a potential concern due to the highly aromatic nature of coal-derived fuel oils. 

EPRI contracted an economic study on the use of Texas lignite in atmospheric fluidized bed combustion (42), and projected that the costs of AFBC would be less than those for pulverized combustion plus flue gas desulfurization. However, while AFBC appears feasible for small-scale units (less than 50 MW ), there is some doubt that large scale utility AFBC systems can operate successfully. Part of this problem stems from the inadequacy of "bubbling bed" design normally used in AFBC newer designs, such as the circulating bed, offer more promise for commercial application and are being tested presently (32). 

T. Furuya, S. Yamanaka, T. Hayata, J. Koezuka, T. Yoshine, and A. Ohkoshi, Hybrid catalytic combustion for stationary gas turbine—Concept and small scale test results, ASME Paper 87-GT-99 (1987). 

With respect to combustion, the research focus will be on improvement of the models regarding tars and their effect on emissions of CO. soot and unburned hydrocarbons (UHC). Part of that research will be the testing of a combustor integrated in an entire 500 kWth small scale gas turbine set-up. 

The experimental test field designed for investigations on the combustion and emission behaviour of solid fuelled small scale firing systems is shown in Figure 2. In order to get measurement results under practical conditions the test field is equipped with an insulated natural draft chimney with a height of 6m. 

ABSTRACT Calcium-enriched bio-oil (CEB) can be used for flue gas desulfurisation in coal and waste combustion chambers. It is produced by mixing biomass derived fast pyrolysis oil with calcium oxide. The aim of the proposed project is to develop a technology i) to produce calcium-enriched bio-oil with a calcium content of 13 wt,%, and ii) to test the CEB in a combustion chamber by co-firing it with a sufur-containing fuel. In this paper the production method of CEB will be elucidated, and small-scale experiments related to CEB spraying will be presented. Finally, co-combustion experiments of a sulfur-containing fuel with CEB in a small flame tunnel (20 kW, ) will be reported. 

CEB will be used for coal and waste combustion, and not primarily for heavy fuel oil. However, the projected large-scale test 7 MW, facility can only use heavy fuel oil. Therefore, this oil was used to test it on a small scale. A small flame tunnel with separate air and liquid fuel injectors was constructed to demonstrate the potential of CEB to recover SO2. Figure 10 shows a photograph of the set-up, with the control panel at the right hand, and the flame tunnel in the middle. The three injection ports for CEB material are visible at the front side. Through the opening in the middle (the nozzle has been removed), the flame from diesel combustion is clearly visible. In all experiments, CEB is sprayed perpendicular to the fuel stream. A portable Mass Spectrometer has been purchased to analyse the exit gases from the flame tunnel experiments on SO2. 

The toxicity of the gas effluent was also reduced (an indication that HCN was not being converted into some compound that was even more toxic). Fewer animal (Fischer 344 rats) deaths occurred during the 30 min exposures to the flexible polyurethane foam treated with the copper and copper compounds compared to the untreated flexible polyurethane foam. Toxicity based on LC50 values was reduced 40-70% in the small-scale tests with 0.1% Cu20-treated foams. The blood cyanide levels in the animals exposed to combustion products from the CuO-treated foams for 30 min were 1/2 to 1/4 of those measured in the animals exposed to the smoke from the same amount of untreated foam. 

Postexposure deaths were also reduced in the animals exposed to the combustion products from the Cu and Cu20-treated FPU foams in the small-scale tests. These delayed postexposure deaths have not been observed in animals exposed to combustion products from flexible polyurethane foams decomposed in large-scale room fire tests. The specific cause of these postexposure deaths is not known. 

One of the additives being used in combustion-modified flexible polyurethane foams is melamine. Small-scale tests conducted at NIST indicated that a melamine-treated flexible polyurethane foam generated six times more HCN than an equal amount of foam that did not contain melamine. The presence of CuiO reduced the HCN from the melamine foam by 90%. Melamine-treated flexible polyurethane foam is one of two flexible polyurethane foams currently allowed in Great Britain. 

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