Bed Moisture Research Articles

Rate of Spread of Free-Burning Fires in Woody Fuels in a Wind Tunnel

We describe the results of 357 experimental fires conducted in an environmentally controlled large wind tunnel. The fires were burned over a range of particle sizes, fuel bed depths, packing ratios, moisture contents and windspeeds. We find that spread rate decreases with moisture content in a way which depends on the fuel type and diameter. It decreases as the square root of the packing ratio. Fuel bed depth has little effect on spread rate, and fuel diameter has significant effect only for diameters above 1 mm. The relationship between rale or spread and windspeed is virtually linear We develop a predictive model for rate of-spread based on energy transfer considerations and the laboratory results. Other laboratory-based models for spread rate are compared with our model, and tested against the laboratory data. The other models have forms similar to ours, but do not predict our data well. Our model predicts well the spread rates for fires burned in windspeeds below 3 m/sec in other laboratories. The scale of the experiments and the similarity of the dependence on windspeed to that found in the field indicate that a field model may be developed from the laboratory model with relatively few modifications.

Properties of a lacustrine subbituminous (k1) seam, with special reference to the contact metamorphism, Soma-Turkey

The subbituminous K1 seam in the Middle Miocene Soma Formation of western Turkey reaches a thickness of 24 m. Typical samples on an air-dried basis have 9.5–14.2% moisture, 4.3–13.8% ash and 0.57–2.54% total sulphur. The coal rank parameters and non-agglomerating behaviour show that the coals are of subbituminous A rank. The k1 seam is huminite-rich coal with a mean random ulminite reflectance (%Rr) between 0.46 and 0.49%. Fluorescence emission measurements show that the sporinite, cutinite, resinite and alginite present have typical fluorescence spectra between 460 and 700 nm. The Soma Formation was intruded by an olivine basalt during the Pliocene-Pleistocene, which caused local contact metamorphism at the top of the k1 seam. On the basis of proximate, ultimate and petrographic analyses the intruded seam can be divided into normal coal, transition zone and natural coke intervals, each differing in their degree of metamorphism. Moisture, volatile matter, hydrogen and oxygen contents very rapidly decrease close to the contact point with the intrusion, whilst calorific value, carbon content and mean random reflectance value increase. A diagram ofO/C versus H/C also shows a distinct increase in rank caused by the intrusion. Minor illite, siderite and plagioclase feldspar are present in the natural coke samples, butpyrrhotite is not observed. Mineralogical, geochemical and reflectance studies indicate that the general temperature during formation of natural coke was probably relatively low (< 650°C), with the coal also under the influence of stress. This relatively low coking temperature is thought to have been related to the insignificant volume and quick cooling of the basaltic magma, the high proportion of bed moisture in the coal and the poor thermal conductivity of the seam.

Performance of a Pilot-Scale Compost Biofilter Treating Gasoline Vapor

A pilot-scale compost biofiltration system was operated at a gasoline soil vapor extraction site in Hayward, Calif. for one year. The media was composed of equal volumes of compost and perlite, a bulking agent. Supplements added included nitrogen (as KNO3), a gasoline degrading microbial inoculum, buffer (crushed oyster shell), and water. The biofiltration system was composed of four identical units with outside dimensions of 1.2 × 1.2 × 1.2 m (4 × 4 × 4 ft) operated in an up-flow mode. The units were configured in parallel during the first eight months and then reconfigured to two parallel systems of two units in series. Air flux values ranged from 0.29 to 1.0 m3/m2 per min. Inlet total petroleum hydrocarbon (TPHgas) concentrations ranged from 310 to 2,700 mg/m3. The average empty bed contact time was 2.2 min. Following start-up, performance of the individual biofilters varied considerably for a seven-month period. The principal factor affecting performance appeared to be bed moisture content. Overall TP...

The geology and coal petrology of a Pleistocene lignite profile at Horemi mine, Megalopolis Basin, Peloponnese (southern Greece)

The present study describes the geology, coal petrology and geochemistry of a Pleistocene coal-bearing succession at Horemi mine, Megalopolis Basin (southern Greece). Within a 45-m interval 9 coal seams are exposed, ranging in thickness from 20 cm to 10 m. Reflectances measured on the maceral-type eu-ulminite B range between 0.24 and 0.31% mean R random. This indicates a coalification stage in the transition zone between peat and lignite rank of the A.S.T.M. classification for the Horemi coals. Petrographic studies demonstrated the immature nature of these coals and the low degree of compaction during diagenesis. Compositionally, the Horemi coals are characterized by low amounts (5.3 vol%) of the inertinite group macerals, moderate amounts (11.9 vol%) of liptinite group macerals and very high amounts (82.8 vol%) of the huminite group macerals (on average and mineral-matter-free basis). Within the latter group densinite, attrinite and ulminite make up the bulk of the samples. Results from proximate and ultimate analysis gave on average 53.7% bed moisture, and 37.3% ash, 45.8% volatiles and 18.1% fixed carbon (d.b). Calorific value determinations vary between 1805 and 5470 kcal/kg. Mineral matter is high, varying within the range 20.8–51.9 vol%. Identifiable mineral constituents include quartz, anhydrite, illite, feldspars, calcite, gypsum and chlorite, and minor amounts of barite and pyrite. Reflectances obtained from ulminite were found to be negatively correlated with volatile matter, whereas there is a trend for a positive correlation of them with calorific values.

Fluidization of potato starch in a stirred vibrating fluidized bed

A novel gas-solid reactor for cohesive C-powders such as potato starch is introduced, designed and characterized, the so-called stirred vibrating fluidized bed. The effects of a sinusoidal vibration of the gas distributor and/or stirring of the bed are investigated. The fluidization index, bed expansion, torque and visual behaviour of the bed are determined as a function of air velocity, bed height and moisture content of the starch, stirrer type and speed and vibration frequency and amplitude. For a potato starch bed of 0.76 m initial height and 0.288 m diameter with a moisture content W = 13.1 weight% dry basis, channel formation can be suppressed only if the aerated bed is effectively stirred. With flat stirrer blades this can be realized for stirring speeds above 1.67 rps provided the interblade distance is below 124 mm. Even then, the bed consists of agglomerates (flocks) of starch. Alternatively, vibration of the gas distributor of the aerated bed at best results in channel elimination in the lower part of the bed only. Sufficient vibration, however, can destroy starch agglomerates even at the surface of a bed of 0.76 m. By simultaneously applying both vibration and stirring of the aerated bed, it is possible to eliminate both channelling and starch agglomeration. Even homogeneous fluidization is possible. Optimal combinations of stirring and vibration parameters are reported for various bed heights and moisture contents.

WATER AND NITROGEN RETENTION IN ANNUAL LANDSCAPE BEDS AMENDED WITH A HYDROPHILIC POLYMER

A study was conducted to test the ability of hydrophilic polymers to retain moisture in annual bedding plant beds in addition to reducing NO3 and NH4 leaching. Petunia plants were transplanted into raised concrete benches containing a drainage pipe that allowed for excess leachate to be collected. Beds that were treated with 0 or 366 g·m–2 of hydrogel and 0 or 186 g of ai N. Watering of beds followed a strict irrigation schedule and soil moisture was monitored daily. At termination, plant dry weight was measured and analyses of plant tissue and leachate were conducted for NO3 and NH4 concentrations. Results from this study demonstrated that, under suboptimal conditions of minimal irrigation and fertilization, polymer incorporation had a significant effect on water, NH4, and NO3 retention in soils. Water leaching was decreased by 17%; NH4 retention was increased by 83%; and NO3 retention, where additional N was added, was increased by 64% due to polymer incorporation. In addition, a 47% reduction in NO3 concentration of water leachate was detected when polymer was incorporated under minimal fertilization. Growth or N levels of petunia were not significantly affected by polymer incorporation.

Heat and Moisture Transfer in Textile Assemblies

We have studied heat and mass transfer in wool, cotton, nylon, and polyester fabric beds during steaming. Our mathematical model, which is based on local volume average methods, considers the finite rates of heat and mass transfer between the solid, gaseous, and liquid phases of the system. Experiments involve the steaming of fabric beds of various types. Theoretical calculations and experimental work focus on the initial stage of steam penetration characterized by steep rises in bed temperature and moisture content. The effects of fiber diameter, absorption rate, bed porosity, and initial regain on the heat transfer front are examined. With a dry bed of wool or cotton fabric, steaming produces a sharp increase in regain at the heat transfer front, accompanied by a significant rise in the bed temperature. With a nylon or polyester fabric bed, the heat transfer front is followed by a "transient equilibrium" period during which the bed temperature remains unchanged.

Coal type and rank variation in Tatu Mine, New Zealand

Tatu State Mine in Taranaki, North Island, New Zealand, worked a Miocene subbituminous coal seam about 2 m thick over an area of nearly 3 km 2. Detailed face sampling of the seam from 1940 to 1961 provided 46 proximate and 15 proximate and ultimate analyses. They show great variation, particularly in moisture, volatile matter, calorific value and sulphur content. The relations between the various analytical parameters exemplify and amplify those found generally within coals from New Zealand and many other countries, providing basic elements for geological study of coal properties. The detailed inferences are: 1. (1) The relation between bed moisture and moisture in coal air dried under standard conditions of 20°C and 70% relative humidity (R.H.) is M B = ∼ 1.1 × M ADS(af). 2. (2) Sulphur content decreases from roof to floor of the seam, with a minor increase close to the floor. Although the sulphur contents of the top ply samples range from >6% to <2% (daf), the decrease from top to bottom plies is in all cases 1.5–2.0%. 3. (3) On the basis of the full seam thicknesses, sulphur content shows a clear areal pattern of variation, ranging from >6% to <1.5% (daf). 4. (4) At one sampling site, sampled in 9 plies, the following relations show the effects of coal type variations: Volatile matter and calorific value (dmmsf): +1% VM = +0.2 MJ/kg Volatile matter (dmmsf) and bed moisture (af): + 1% VM =c.−0.4% M 5. (5) Almost all coals lie within the New Zealand Coal Band. A few are lower in volatile content; rather more are higher. 6. (6) On the basis of the full seam thickness, volatile matter, ranging from >51% to <45%, shows a clear areal pattern of variation. 7. (7) The patterns of variation of volatile matter and sulphur are similar, the relation between them being: + 1% S (daf) = +1.5% VM (dmmsf). Although sulphur, introduced from sea water when overlying marine beds were deposited, appears to have affected coal type, as judged by volatile matter, petrographic data are needed to study this further. 8. (8) Rank of dry coal, in terms of Rank (S) (Suggate, 1959), increases westwards from rank ∼7.5 to >8.5. 9. (9) Moisture content shows no significant rank-related variation. 10. (10) Taken individually, almost all samples would be ASTM rank subbituminous A, but particularly high-volatile samples would be High-volatile C and B bituminous. Production from the mine has always been subbituminous coal.

Transient Heat and Moisture Transfer in Thin Silica Gel Beds

A numerical model has been developed to simulate the transport of heat and moisture in thin beds of microporous silica gel, assuming surface and pore volume diffusion of moisture and conduction of heat as the dominant intraparticle transport mechanisms in the desiccant. Predictions from the model have been compared with the results of single-blow tests for packed beds of silica gel from the literature and for a matrix of silica gel-coated parallel passages from this study. The model has been used to explore the significance of intraparticle diffusion resistance to heat and moisture transport in packed beds and parallel passage matrices of silica gel for different desiccant sizes and air velocities.

055 FRUITING RESPONSE OF STRAWBERRY IS AFFECTED BY K RATES

During the 1992-93 fruiting season, straw berry plants were fertigated weekly with either 0.28, 0.56, 0.84, 1.12, or 1.40 kg/ha/day of K derived from KCl. Other nutrients were applied in the plant bed before fumigation except for N which was applied at 0.84 kg/ha/day by fertigation. Soil moisture in the plant beds was maintained between 10 and 15 cbs. Initial soil K tested medium with the Mehlich I soil test. Seasonal average fruit weight and percent marketable fruit decreased with increasing K rate. Seasonal fruit yields did not increase with K rates above 0.56 kg/ha/day. Leaf K concentrations increased with increasing K rates throughout the harvest season. The leaf K concentrations in the 0.28 K treatment were below 1% during the last month of harvest. K rates did not affect fruit firmness.

Automation of the Manufacturing Process of Cold Remedy Granules by a Tumbling Fluidized Bed Applying the Fuzzy Control Method.

The automated manufacturing process of cold remedy granules using a tumbling fluidized bed will be described.Powdered materials, containing salicylamide and acetaminophen as the main components and having been used for the extrusion process previously, were granulated by a tumbling fluidized bed. Effects of the operational variables on the properties of granules were investigated, which led to the conclusion that the exact control of bed height and moisture content was indispensable for continuously producing desired granules. The fuzzy control method based on a linguistic algorithm of if-then rules was applied to the bed height control, and programmed control of the moisture content was used for the continuous operation from mixing, granulation to drying. By means of the system developed, a series of operations could be conducted automatically. Properties of the granules thus obtained were evaluated, and a comparison of the granules by this process to those by the extrusion process used previously was conducted.It was concluded that by means of the control system developed, desired granules which had sharp particle size distribution, high yield, i.e., almost 100% of granules, large apparent density and remarkably good flowability were easily produced.

Depths of burial of eastern Southland lignites, estimated from their moisture contents

Abstract Bed moisture Contents range from c. 64% to 41% in eastern Southland lignite fields, being lowest in the northwest. The rates of decrease of moisture with depth in drillholes vary, being greatest in the higher moisture areas. The rates are generalised from 19 drillhole sequences and extrapolated to 90% moisture in the original surface peat. This leads to estimated former maximum depths of burial of an Early Miocene pollen zone boundary ranging from 160–200 m in the south to 700–800 m in the northwest. Where subsidence was greatest, possibly towards the faulted margin ofafault-angle depression, subsequent uplift was also greatest. For lignites of average type, the ASTM Lignite A/Lignite B boundary in eastern Southland is estimated to have been reached at an original depth of burial of c. 650 m.

Development of a technique to study seedling emergence in response to moisture deficit in the field —The seed bed environment*

SummaryThe ability of crops of sorghum (Sorghum bicolor (L.) Moench) to establish in farmers' fields depends largely on its capacity to germinate and emerge under limited soil moisture conditions. Studies on germination under moisture stress have been previously conducted using osmotic media which do not wholly reproduce the conditions of the seed bed in the field. Hence the need for a field screening technique. A line source irrigation system was used to provide five moisture regimes ranging from ‐0.08 MPa to ‐0.92 MPa. The drying rate of the soil and the soil temperature depended largely on incident radiation, and the relationship between the moisture content and daily soil temperature and daily radiation was consistant. Total porosity of the seed bed, derived from bulk density measurements and particle density ranged from 43.8% to 45.3%, which would allow sufficient aeration when as in the experiments conducted here, water content was low (&gt; 0.14 g/g). Under these seed bed conditions the pattern of response of emergence to the moisture gradient was linear or curvilinear. Genotypic differences existed for emergence and its response to water level. The field method developed is useful for identifying genotypes able to germinate and emerge under conditions of low seed bed moisture.

Petrographic and coalification variations in the Eastern Southland lignites, New Zealand

The Upper Oligocene to Lower Miocene Gore Lignite Measures of Eastern Southland accumulated in humid temperature to subtropical wet forest swamps in a coastal delta-plain paleoenvironment. The lignites have relatively low ash and low sulphur contents. They are xylitic, contain abundant resinite and range from poorly to strongly gelified. Petrographically, they are relatively uniform and dominated by humic macerals. The Eastern Southland Lignite Field can be divided into a southern (lower-rank) and a northern (higher-rank) area. The lower-rank lignites have bed moisture contents of 55–61% whereas the higher-rank lignites have bed moistures of 42–46%. In both areas the lignite seams are within 200 m of the surface but are probably separated by faults and have undergone separate burial and tectonic histories. Burial depths are believed to range from 250 m for lower-rank to 1100 m for higher-rank lignites. The rank increase from south to north is largely the result of compaction-induced reduction in porosity and consequent dewatering and is not accompanied by any notable increase in gelification. For these lignites, there is a linear relationship between bed moisture and fixed carbon but a significant shift away from the linear relationship between volatile matter and specific energy and bed moisture. Also, the higher-rank northern lignites have higher H:C and lower O:C atomic ratios than the southern lower-rank lignites. These geochemical changes are heat- and depth-related and represent changes in functional group composition that are independent of observed gelification.

A progress report on the Alpern Coal Classification

The Alpern Coal Classification has already been largely utilized and successfully applied, both to Laurasian (North Atlantic) and Gondwana coals. It was accepted on basic principles by the International Committee for Coal Petrology, and, as the official contribution of France, it has been recently also partly adopted by the Economic Commission for Europe of the United Nations in Geneva (1988). This paper deals with the improvement of the previous versions of the classification, mainly by introducing new statistical data in order to establish more accurately proposed rank limits. A ternary division for RANK is maintained with the categories: low-rank coal or lignite (instead of brown coal because high-rank lignites may be black not brown), medium-rank coal or bituminous coal, and high-rank coal or anthracite. The prefixes hypo-, meso- and meta-, are used for rank subdivision, thus avoiding non-coherent previous prefixes such as sub-(bituminous) and semi-(anthracite). The selected rank parameters are: moisture holding capacity (ash free) and calorific value (moist, ash free) for lignites, mean random reflectance for bituminous coals and anthracites. Correlations for bed moisture (ash free) and calorific value (dry, ash free) are given for lignites. Correlations for volatile-matter content, mean maximum vitrinite-reflectance, and hydrogen content are also given for bituminous coals and anthracites. TYPE is determined from maceral data and is divided into: vitric (vitrinite (V) > 60%), fusic [V < 60%; inertinite (I) > liptinite (L), and liptic (V) < 60%; L >. I). The ash content and the washability potential at 10% ash level are used to determine GRADE (or FACIES) and allow the distinction between transportable clean coals and non-washable coals. The run-of-mine ash content (dry basis) permits the division between: coal, middlings, and shale. If the type is liptic, the subdivisions “sapropelic coals” and “oil shales” are used. These are not washable but are solid fuels with a positive energy potential. If the coals to be classified are clean (or washed) the vertical axis becomes free and can be used, for example, for swelling properties in bituminous coals. The system has been recently computerized and allows for data to be displayed effectively for all relevant fields of application. Computer-output examples are presented for coals from a Euramerican and a Gondwana basin.

A THIN LAYER METHOD FOR THE INVESTIGATION OF BULK DENSITY AND AIR FLOW RESISTANCE DISTRIBUTIONS DURING DEEP BED DRYING

ABSTRACT A thin layer experimental method is presented for the investigation of the effect of compression and drying on bulk density and air flow resistance. A thin layer was subjected to a compressive load and ventilated with drying air to simulate the conditions within a deep bed. The technique is analogous to thin layer drying work and in the same way produces thin layer equations which can be incorporated in deep bed simulation programs. It was found that for a bed of germinated barley (malt) the volume change could be considered in terms of three components: initial compaction, transient settling and drying shrinkage. These were correlated with bed pressure, time and moisture content reduction. The effect of initial compression and settling was shown to produce bulk density variations of the order 20% in 1.5 metre beds. Drying shrinkage was found to produce a height reduction of the order 15%. The pressure gradient due to air flow resistance was increased by as much as a factor of six as a result of compression. Moisture content did not have a great effect on air flow resistance.

The chemical properties and composition of Mokau coal

Abstract Chemical and physical analyses carried out on Mokau coal as part of the recently completed New Zealand Government prospecting programme are treated statistically to define mean properties in-ground for each seam of each sector and to show geographical trends within and between seams. Properties studied include bed moisture, air-dried moisture, specific energy, volatile matter, sulphur, forms of sulphur, coal composition, mineral composition, ultimate analysis, ash constituents, trace elements, ash distribution, boiler fouling properties, ash fusibility, Hardgrove Grindability Index, and relative density. The median in-ground properties range from 15.9% moisture, 7.2% ash, 35.4% volatile matter, 41.5% fixed carbon, 23.14 MJ/kg specific energy, 1.6% sulphur (Mangatoi seam 1) to 14.4% moisture, 9.1% ash, 40.9% volatile matter, 35.6% fixed carbon, 23.76 MJ/kg specific energy, 4.7% sulphur (Manga-Awakino seam 5). The mean coal composition (dry, mineral free basis) ranges from 69.6% carbon, 4.85% hydro...

LOW‐RANK SEQUENCES AND SCALES OF ORGANIC METAMORPHISM

Degrees of alteration of carbonaceous material, when compared with scales of organic metamorphism, are used mainly by petroleum geologists for estimating conditions of development of sedimentary basins and for estimating the likelihood of oil and gas generation having taken place. For accurate estimation, especially of geological history, the scales need to be correctly designed, and low‐rank sequences (lignite, sub‐bituminous and high‐volatile bituminous ranks of coal) are critical for this. Scales need review, and data from surface and drillhole sequences in New Zealand are valuable for this. The generally‐accepted influence of time is considered unproved and unlikely to be significant.In order to relate the concept of “rank” to the geological conditions, it is necessary to use more than one parameter, and the best for use with low‐rank sequences are the dry‐basis calorific value and the bed moisture. Correlation of degrees of metamorphism with particular geological histories is not possible for high‐rank sequences.

Resource Evaluation of Gas-Bearing Coal Beds: ABSTRACT

Bituminous and subbituminous coal deposits in the United States are a significant fossil fuel resource. Furthermore, a large methane gas resource is trapped in these coal beds and associated strata. Distribution and resource assessment of these potential gas reserves in 380,000 sq mi (988,000 sq km) of coal-bearing strata is currently under investigation. Diagnostic techniques include regional and local geologic studies, mud log evaluations, geophysical wireline logging with associated digital interpretation in both open and cased boreholes, conventional and sidewall core analyses, drill-stem and production testing, and coal bed stimulation techniques. Integration and analysis of the resultant data provide valuable information as to coal bed thickness, coal rank, ash and moisture content, coal permeability, face and butt-cleat orientation, gas content, pressure, and flow potential. Overburden characteristics and the elastic rock properties of the floor and roof rocks, such as Young's modulus, bulk modulus, shear modulus and Poisson's ratio, are determined from logging techniques and provide information important to mine design, mining operation, stimulation of gas-bearing coal beds, and in-situ coal gasification projects. End_of_Article - Last_Page 774------------

The influence of bed moisture on fluidization characteristics of fine powders

The effect of bed moisture on fluidization characteristics of fine powders has been studied. Beds of glass microspheres and catalytic particles have been tested at variable water content and gas velocity up to the minimum for bubbling. Measurements include bed permeability, settled and fluidized bed voidages. Results indicate that the sensitivity to moisture drastically changes from porous to non-porous materials. There are also differences among porous materials with regard to the effect of water content on minimum velocity for fluidization and for bubbling, and on voidage—velocity relationship in the bubble-free range of fluidization.