Hot Sand Research Articles

Rice Protein Aggregation During the Flaking Process

The effect of roasting of soaked paddy rice and its subsequent flaking during production of rice flakes on solubility of rice proteins in various solvents was investigated. The solvents were so chosen to provide an understanding of the type of protein–protein interactions occurring during processing. There was an increase in protein solubility upon roasting of soaked paddy in fine hot sand (175–250°C) – a prelude to the flaking process – however, after subsequent flaking solubility decreased. Gel filtration studies indicated that aggregates with molecular weights greater than 4×107kDa formed during flaking as a result of disulphide bonding. The aggregates were composed of 68, 31–34 and 24 kDa proteins. Of these, the 31–34 kDa proteins were identified as «putative prolamins». These proteins require detergent for their initial solubilisation. The prolamins of 13–16 kDa were not involved in the formation of aggregates. Their solubility decreased after flaking. The higher molecular weight proteins involved in aggregate formation were susceptible to proteolysis, whereas the 13 kDa prolamin was resistant.

The combustion of propane and air as catalyzed by platinum in a fluidised bed of hot sand

Electrically heated beds of silica sand have been fluidized by mixtures of propane and air, which attain the temperature of the bed very quickly. With the bed below 760°C, these gases burn only in the bubbles bursting through the upper surface of the sand. With beds slightly hotter than 760°C combustion occurs in bubbles during their ascent through the fluidized sand. At ≈900°C, the gas mixture burns in the small bubbles formed at the distributor of the bed: below 1000°C, no combustion of C 3 H 8 appears to occur in the particulate phase, that is, between the sand particles, but only in the bubble phase. However, when catalyst pellets (of Al 2 O 3 coated with Pt) are added to fluidized sand below 760°C, measurements of [CO 2 ] in the bed reveal that C 3 H 8 oxidizes on the Pt. The measured temperature difference between a catalyst particle and the cooler sand shows that the catalyzed burning of C 3 H 8 on Pt is first order in C 3 H 8 and zeroth order in O 2 . The reaction is that producing CO and H 2 O from C 3 H 8 : actually the CO tends to diffuse well away from the catalyst before burning, most probably in a bubble. However, some limited oxidation of CO to CO 2 can occur on the platinum. The overall rate of oxidation is controlled by mass transfer of C 3 H 8 from the particulate phase to a catalyst particle. Thus, sand inhibits the combustion of C 3 H 8 in air, whereas platinized alumina particles catalyze it, thereby enabling more of the heat of combustion to be released inside a fluidized bed. The above considerations are affected by some of the off gases being recycled back into the bed, when U/U mf >6.

Simple rapid processing of African oil bean seeds for ugba production

Toasting oil beans in hot (100°C)sand and holding for a further 30 min at 100°C significantly improved dehulling, and the bitter taste was removed by slicing to 1 mm, boiling for 30 min and soaking for 2 h. This simple process achieved the same quality of ugba after fermentation as the much more cumbersome, fuel‐wasting and time‐consuming traditional technique, saving up to 2 days.

Protein Oxidation of a Hair Sample Kept in Alaskan Ice for 800–1000 Years

Ancient finds of organic matter are not only of the highest value for palaeochemists and palaeobiologists but can be used to determine basic chemical reactions, such as protein oxidation, over long time periods. We studied oxidation of human hair protein about one thousand years old of an Alaskan child buried in ice, ten hair samples of Copts of comparable age buried in graves of hot dry sand and compared the results to ten recent hair samples. Protein oxidation parameters o-tyrosine and cysteic acid of the Alaskan child were comparable to recent samples whereas they were higher in the coptic specimen. N-epsilon-carboxy-methyllysine, a parameter for glycoxidation, however, was as high in coptic specimen. We conclude that ice in contrast to soil prevented protein oxidation but failed to inhibit glycoxidation, a reaction initiated by autoox-idation of glucose. This study therefore has implications for the interpretation of oxidation and glycoxidation as well as preservation mechanisms of proteins.

Development of Weaning Foods Based on Malted, Popped, and Roller-Dried Barley and Chickpea

The optimum conditions for malting barley and chickpea were standardized, and a malted weaning food (MWF) formulation was prepared by blending 48-hour germinated barley and 24-hour germinated chickpea flours. Decorticated barley was mixed with 7% additional water, tempered for four hours, and popped in hot sand medium. Popped barley was mixed with popped chickpea to formulate popped weaning food (PWF). Flours from decorticated and mild toasted barley and chickpea were mixed with water and the slurry was roller dried to prepare the roller-dried weaning food (RWF). The food formulations consisted of 60% processed barley, 30% chickpea, 5% skim milk powder, and 5% cane sugar. Popped and roller-dried weaning foods were mixed with 5% malted barley flour to prepare the low-dietary-bulk formulations of popped weaning food with malt (PWFM) and roller-driea weaning food with malt (RWFM). The protein content of the formulations ranged from 14.8% to 15.6%. The viscosity of the cooked paste of MWF, MWFM, and RWFM, was much lower than that of DWF and RWF at all comparable slurry concentrations. The energy content of the gruels of MWF, MWFM, and RWFM at spoon-feeding consistency was about 1.1 kcal/g. The protein efficiency ratio (2.6–3.1), biological value (93–97), true digestibility (85–87), and net protein utilization (79–84) of the formulations indicated good growth-promoting quality of the food proteins.

Locomotory Behaviour in a Population of the Tiger Beetle Species Cicindela hybrida on a Small, Hot, Sandy Area (Coleoptera: Cicindelidae)

The locomotory behaviour of tiger beetles on a very hot, sandy area is described. Running speed and propensity to run was higher at higher surface temperature T s . Maximum running speed was at least 50 cm s -1 at maximum surface temperature of T s = 53.5°C, measured between l.oo and 3.oo h pm. Periods of rest on the hot sand did not last longer than 01-10 s. Sudden transitions to flights of up to 3 m s -1 were observed when the beetles were disturbed. In the evening, at T s 20°C, the beetles run slowly (v 20 cm s -1 ) for short distances and usually refrained from flying, even when disturbed. Any prey found during the day at T s 30°C was attacked immediately and repeatedly grasped, released and regrasped, even smooth insects such as Coccinellidae. At T s 30°C, body position was oblique, and the head held 5-6 mm above ground. At higher temperatures body position was steeper. With the legs fully stretched (at T s 40°C on), the head was approximately 10 mm above ground, thus obviously escaping heat radiation from the surface. The beetles only remained in the shadows of grasses or branches during extremely high temperatures (T s 45°C). Surface and near surface temperatures as well as temperature profils near the ground of the biotope were recorded under various ambient conditions (sun, clouds, wind, time of day) and correlated to the beetles' locomotory behaviour.

Studies on preparation, popping and functional properties of bulgur wheat

AbstractWheat was steeped to 36% moisture and agitated for 2 min in sand heated to 170 °C. This dry heat bulgur was comparable to bulgur prepared by steam treatment. The dry heat bulgur of 14% moisture content was popped in hot (230 °C) sand medium. The expansion ratio of popped bulgur was 2.1. Some of the functional properties of popped bulgur flour were compared with native, 48 h malted and roller dried wheat flours. Water absorption index was highest for roller dried followed by popped and malted wheat, whereas water solubility index was highest for malted followed by roller dried and popped wheat. Roller dried wheat exhibited higher cold paste viscosity (360 BU) than popped (30 BU) wheat. Popped wheat had a peak viscosity of 300 BU. The viscogram of malted wheat was typical of cereal flours when the enzyme activity of malt was inhibited. The gel permeation chromatograms of popped and roller dried wheat indicated thermal degradation of starch during popping and roller drying. The in vitro carbohydrate digestibility of popped wheat was higher than roller dried and malted samples. The scanning electron microscopic examination of native and popped bulgur revealed that the endosperm of bulgur wheat was a homogenous mass containing gelatinized starch whereas that of popped bulgur was made up of thin layers of popped starch with irregular air spaces.

Kinetic study of the flash pyrolysis of almond shells in a fluidized bed reactor at high temperatures

Two correlation models have been developed and applied to simulate the primary and secondary reactions (assuming first order kinetics for both reactions) as well as the heat transfer in the pyrolysis of almond shells in a system with a fluidized bed reactor. The biomass is discharged onto the hot sand fluidized bed. The primary decomposition takes place during the fast heating of the particle inside the sand fluidized bed. The cracking of the volatiles evolved takes place in the upper part of the reactor, from the top of the sand bed to the heat of the reactor. The first model calculates the kinetic constants of the primary and secondary reactions in the pyrolysis. The apparent activation energy for the primary reaction is very low, showing the effect of the heat transfer. The primary kinetic constant obtained should be considered as a correlation constant, including both the chemical reaction and the heat transfer. A second model was developed with different assumptions concerning distinct kinetic expressions for the primary reactions obtained from the Pyroprobe 100 and TGA, considering heat transfer to the particle. The heat transfer from the fluidized bed to the almond shell particles as well as that from the wall of the reactor to the volatiles has also been considered. The model reproduces the experimental data very well and the constants obtained compare favorably with published data, both for kinetic constants and for heat transfer numbers.

Development and nutritional quality evaluation of weaning foods based on malted, popped and roller dried wheat and chickpea

SummaryOptimal conditions for malting wheat and chickpea for preparation of weaning foods were standardized and malted flours from 48 h germinated wheat and 24 h germinated chickpea were blended to prepare malted weaning food. Wheat was dry‐heat‐parboiled (bulgurized), popped in hot sand and blended with popped chickpea flour to prepare popped weaning food. Mildly toasted and debranned wheat and dehusked chickpea flours were mixed and the blend was roller‐dried for preparation of roller dried weaning food. the formulations had 60% wheat, 30% chickpea, 5% skim milk powder and 5% sucrose and contained about 16% protein. the cooked paste viscosity (dietary bulk) of malted food, popped food with malt, and roller dried food with malt was significantly lower than popped and roller dried foods at all comparable slurry concentrations. the energy density of malted and malt‐added food slurries at spoon feeding consistency was 4.2 KJg−1. PER (2.91), biological value (88.3) and true digestibility (87.5) values of malted food were higher than that of the other formulations.

Process modelling on a novel grain roaster

A manually operated device for roasting and puffing grains by using hot sand was developed. By means of a built-in sieve, the roasted grain could be removed while retaining hot.sand within the device. The moisture diffusivity in bengalgram during roasting was estimated to be 10 × 10 −9 m 2 s −1 and the overall heat-transfer coefficient for the heating of sand with a liquefied petroleum gas was 12 W m −2 K −1. The temperatures of the sand and the grain and sand mixture were determined by using a lumped-heat-capacity model. The grain and sand temperature at the end of roasting as predicted from the model was between 207 and 222°C, while the measured values were from 201 to 205°C. The roaster could roast 4·2–4·9 kg h −1 of bengalgram while our model predicted 4·4–5·3 kg h −1.

ENGINEERING AND QUALITY ASPECTS OF PARTICLE-TO-PARTICLE HEAT TRANSFER TO BLACK BEANS

A hot sand roaster was used for drying, desinfestation and inactivation of enzymes in mature and dry black beans. Measured transient temperature inside beans agreed values calculated using a model for heat transfer into an ellipsoid. Overall heat transfer coefficients during the transient period (less than 2 min) ranged from 171 to 281 W/m2 °C for sand temperature between 100 and 140°C. Moisture removal from dried beans (15–17% moisture content) varied between 1 and 4.5 percentage points and correlated well with the final temperature of the sand. Roasting mature beans at different moisture levels was effective for inactivating peroxidase, enzyme believed to be involved in deteriorative reactions in dry beans. Infestation was also controlled with a mild roasting. A disadvantage of roasting was the structural damage of the outer cotyledon cells as studied with SEM. Particle-to-particle roasting proved to be a simple and effective pretreatment to preserve quality of dry beans during storage.

The effect of solar drying and heating on the hardness of Phaseolus beans during storage

Small white beans ( Phaseolus vulgaris) were dried and heat processed before storage. Water removal in a solar drier was four times faster than conventional field drying in the pods. Heat treatments included particle-to-particle roasting using hot sand, and microwave heating. All samples stored for 212 days at low moisture contents (4–5%) showed a slow rate of hardening at a low temperature of 18°C and a high temperature of 34°C. However, heat treated and control beans became much harder when stored at a humidity of 9% and a temperature of 34°C. Heating and solar drying are effective treatments prior to bean storage, as they greatly reduce moisture to safer levels.

PARAMETERS AFFECTING GRAIN DRYING BY IMMERSION IN A HOT PARTICULATE MEDIUM

ABSTRACT High temperature particulate medium conduction grain drying is a very promising technique. However, lack of basic drying characteristic information has resulted in unsuccessful attempts to develop an efficient, economical, continuous flow dryer. In this study, the effects of initial grain moisture content, initial medium temperature, medium particle size, medium to grain mass ratio, and contact time on the drying of shelled corn immersed in hot sand are evaluated. Moisture losses ranged between 0.2 and 5.2 percentage points (wb).

Modelling on Cooling Of Hot Sand for Metal Casting

In order to establish the optimum control system of hot sand cooling in foundry, a mathematical model for cooling process has been studied, The present study is especially directed towards modelling on dynamical behavior of the process in onepass fluidized bed. The model includes linear differential equations for phase-to-phase heat transfer, Computer simulations on both transient and steady-state temperatures of the bed are provided and compared with the experimental results Sensitivity analysis of the cooling model has been carried out. A special interest is in the variation of steady-state bed temperature owing to the change of inlet sand temperature. The results of computer simulation are presented and comparison with the experiments is done. The proposed model is shown useful in predicting process characteristics of sand cooling system and in designing the optimum cooling system.

Development Status Of The Taciuk Oil Sands Processor

Abstract The Taciuk Direct Thermal Processor has been under research and development since late 1974 in Calgary, Alberta, Canada. This work has been carried out by the UMATAC Industrial Processes Division of Underwood McLellan Limited, Consulting Engineers, under funding agreements with the Alberta Oil Sands Technology and Research Authority (AOSTRA). Original research work and small-scale testing was completed by 1977 when a financing agreement for pilot plant construction and testing was signed with AOSTRA. Under this agreement a pilot plant was constructed in 1977-78, and has been operating for a period of 6 years using the following feed stocks:Athabasca Oil Sandslow grade - 6% oil contentmedium low grade - 9% oil contentaverage grade - 11–13% oil contenthigh grade - + 13% oil contentU.S. Semi Consolidated Sand-Shale low grade - 6–8% oil contentHeavy Oil from Lloydminster FieldHeavy Oil Atmospheric Tower Bottoms from Local Refineries. During 1981 and 1982 the pilot plant was operated on heavy oil and oil sands to provide confirmation data, and oil product samples for detailed oil analysis which resulted in hydrotreating requirement projections. During 1983 UMATAC has completed the design and cost estimates for a 100 ton/ hour demonstration plant to be located in the Fort McMurray area. UMATAC has also completed the conceptual design and cost estimates associated with use of the process in a commercial oil sandplant with an output of approximately 115,000 barrels of synthetic crude per calendar day. Processor Description The Taciuk Processor consists of a horizontal rotating vessel containing compartments which house individual process steps. Figure 1 schematically shows the arrangement and process flows. As-mined oil sand feed is introduced into the preheating section of the processor where connate water is evaporated as steam, frozen material is ablated, oversize is removed and the oil sand is heated by heat exchange with the hot outgoing tailings sand. The heated oil sand is then transported into the reactionzone where it is mixed with hot combusted sand from the combustion zone. The resulting temperature is adequate to thermally crack the hydrocarbons yielding a vapour stream containing the cracking reaction gases and liquids (in vapour form), and a coke residue coating on the sand. The vapour stream is passed through cyclones to remove fine solids and then enters a fractionating tower where various liquid fractions are separated for further processing. The off-gases are then passed to a central gas processing plant for light end recovery and desulphurization. The coke-coated sand dicharges into the combustion zone where preheated air is injected to burn most of the coke. Auxiliary burners provide heat for startup and trim control. The hot sand from the combustion zone passes through arecycling arrangement that ensures an adequate supply of heat to the reaction zone while allowing net sand to move Into the cooling zone. In this zone the sand and combustion gases are cooled by heat exchange with the incoming oil sand.

Drying wheat with solid heat transfer medium

AbstractLaboratory experiments have shown the feasibility of drying milling wheat from 17.0 to 14.5% moisture content using hot sand. The amount of moisture removed increased with the increase in residence time from 1 to 2 min but decreased when the residence time was increased to 3 min. Heated sand to wheat mass ratios ranging between 3:1 and 5:1 were found to be effective in removing moisture from wheat with sand temperatures ranging from 90 to 105°C.

Sticker of Hot Green Sand to Various Patterns

Sticker of Hot Green Sand to Various Patterns

Hot Sand Sticker to the Pattern Surface

Hot Sand Sticker to the Pattern Surface

Swelling and solubility behaviour of parboiled rice flour

SummaryParboiled rice flour swelled and dissolved more than raw rice flour in water at temperatures below 70°C, but less than raw rice at higher temperatures. This difference between raw and parboiled rice increased with an increasing degree of parboiling. A sample of parboiled rice produced by dry‐heating soaked paddy in hot sand behaved differently; but when it was wetted and tempered to favour reassociation of starch, its properties fell in line with normal steam‐parboiled rice. The above behaviours of raw and parboiled rice flour were similar to those of corresponding whole‐grain rice. They also reinforce the earlier suggestion of starch reassociation in conventional parboiled rice.

Properties of Hot Sand

Properties of Hot Sand