Increase In Steam Pressure Research Articles

Experimental study on effect of submergence depth on steam jet shape characteristics in direct contact condensation

The phenomenon of direct contact condensation is frequently utilized in the industrial sector due to low driving potential requirements and proficient heat and mass transfer characteristics. This experimental study investigates the influence of nozzle submergence depth by condensing steam through a straight pipe (SP) and converging-diverging (CD) nozzle. The effect of operating conditions i.e. steam pressure and water temperature in addition to nozzle geometry were also studied on steam cavity shape characteristics. Six different shapes were manifested including unstable, conical, ellipsoidal, cylindrical, divergent, and double expansion-contraction. The dimensionless penetration length of plumes was observed in a range of 1.46–3.91 and 2.14–4.41 for the CD and SP nozzle, respectively while the maximum expansion ratio was determined to be 1–1.25 for the CD nozzle and 1.16–1.58 for the SP nozzle. It has been observed that jet length increases with an increase in submergence depth, steam pressure, and water temperature. The maximum expansion ratio was observed to decrease with the increase in submergence depth and increase with an increase in steam pressure and water temperature. The empirical correlations for dimensionless penetration length were developed and predicted results were found to be lying between ±10 % and ±7 % for CD and SP nozzle respectively.

Structure, thermal stability, physicochemical and functional characteristics of insoluble dietary fiber obtained from rice bran with steam explosion treatment: Effect of different steam pressure and particle size of rice bran

Rice bran was modified by steam explosion (SE) treatment to investigate the impact of different steam pressure (0.4, 0.8, 1.2, 1.6, and 2.0 MPa) with rice bran through 60 mesh and rice bran pulverization (60, 80, and 100 mesh) with the steam pressure of 1.2 MPa on the structure, thermal stability, physicochemical and functional characteristics of insoluble dietary fiber (IDF) extracted from rice bran. IDF with SE treatment from scanning electron microscopy images showed a porous honeycomb structure, and lamellar shape in IDF became obvious with the increase of steam pressure. The relative crystallinity and polymerization degree of crystalline regions in IDF from rice bran with SE treatment from X-ray diffraction analysis were decreased. Differential scanning calorimetry results showed that thermal stability of IDF with SE treatment increased with the increase of crushing degree. The results of FT-IR also suggested that some glycosidic and hydrogen bonds in IDF could be broken, and some cellulose and hemicellulose were degraded during SE process. The physicochemical and functional characteristics of IDF, including water-holding capacity, oil-holding, glucose adsorption capacity, α-amylase and pancreatic lipase inhibition capacity were decreased with the increase of steam pressure and crushing degree. The swelling and nitrite adsorption capacities of IDF were increased first and then decreased with the increase of steam pressure. The physicochemical and functional characteristics of IDF from rice bran were improved after SE treatment, which might provide references for the utilization of IDF from rice bran with SE treatment.

Analysis of the Operating Energy Variables Involved in Mechanized Khoa Production

Significant portion of the total milk production of India has been utilized for the manufacture of the Traditional Indian Dairy Products (TIDP). Khoa based products were traditionally produced in the Indian sub-continent since ancient times. Khoa produced by the mechanized methods can overcome the demerits of traditional manufacturing methods like insufficient use of energy, poor hygiene and sanitation, non-uniform product quality, etc. In the present study, steam jacketed open type hemispherical kettle equipped with spring loaded Teflon edged scraper blade assembly was utilized for the mechanized production of khoa. A standardized mixed milk having (6.0±0.1%) fat and (9.0±0.2%) SNF, was evaporated to the different level of concentration using a batch type vacuum pan. The performance of the mechanized manufacture of khoa was evaluated at different steam pressures (P1= 98.06 kPa, P2=147.1 kPa, P3=171.61 kPa), scraper speed (R1=0.67rps), and different level of milk concentration (C1=35 %TS, C2=40 %TS, C3=45 %TS) for first stage. During the second stage, effect of operating variables on process mechanization were evaluated at different steam pressures (S1= 49.03 kPa and S2= 78.45 kPa) and scraper speed (R2=0.33rps). The primary objective of present study is to carry out thermal and electrical energy analysis associated with mechanized khoa production, which has a significant role in process optimization, scale-up of the operation and to design and fabricate the mechanized system. The overall heat transfer coefficients (U-values) of the mechanized system obtained at various processing parameters ranged from 156.87 to 234.16 W/m2K during khoa manufacturing. The treatment C1 P1 S2 gave the highest U-values for sensible and latent heating. The mean U-values of sensible heating and latent heating were increased with an increase in steam pressure during khoa making in the mechanized system. The mean value of specific steam consumption (kg steam/kg water evaporated) for the optimized operating conditions was 1.950 (kg steam/kg water evaporated) for manufacture of khoa in mechanized system. The total heat losses of mechanized system during manufacture of khoa was 17.15 to 28.02 % at different operating conditions studied. The mean values of electrical power consumption ranged from 141 to 203 Wh under different operating conditions. Considering the energy consumption data, we can narrate that existing system is energy efficient with lower electrical energy consumption and can reduce the labour cost due to mechanization.

Study of steam jet characteristics and regime maps for bevelled spray nozzles exhausting into quiescent water

Steam-water direct contact condensation phenomenon is being widely used in industrial applications due to its rapid heat and mass transfer rates. The present experimental study explores the underlying physics of the steam jet characteristics by condensing supersonic steam exhausting from five different bevelled nozzles into quiescent water tank. Based on the image processing approach, the effects of steam pressure, water temperature and nozzle exit inclination angle on the size and shape of the steam jet have been studied. The dimensionless steam jet length and maximum expansion ratio have been found in the range of 1.18–5.64 and 1.03–2.70, respectively. The results show that the dimensionless penetration length increases with the increase of steam pressure and water temperature, and decreases with increase in nozzle exit inclination angle. Similarly, maximum expansion ratio of steam jet increases with steam pressure, water temperature and nozzle exit inclination angle. It was observed that steam jet exhausting from bevel nozzle undergoes deflection from its nozzle symmetry axis. The deflected angle increases with steam pressure and nozzle exit inclination angle. A theoretical model of steam jet length for bevelled nozzle has also been presented whose accuracy is found to be within ±30% of the experimental data. Additionally, condensation regime diagrams have been proposed on the basis of steam pressure, water temperature and nozzle exit inclination angle. Existence of seven different plume shapes in regime maps have been identified.

Combustion of Plastic Pyrolysis Oil in Steam-Atomizing Burner and Its Application for Pyrolysis Process

In recent years, there has been growing interest in alternative energy sources to fossil fuels. One of them is plastic pyrolysis oil (ppo) that converted from plastic waste by the pyrolysis process. The oil could be used as a fuel for combustion process in some industries. The performance of ppo combustion in steam-atomizing burner was investigated to determine the feasibility of diesel oil displacing in pyrolysis process heating. A prototype steam-atomizing burner was installed to burn plastic pyrolysis oil, with variable 3, 6, and 9 bar steam pressure, to pyrolyze 10 kg/batch low density polyethylene (LDPE) waste in a batch reactor. The pyrolysis process was maintained at 3500C along 2 hours at atmospheric condition. The flame temperature, the length of flame, fuel consumption, heating rate, and pyrolysis yield was observed along the process. The experiment shows that the increase of steam pressure will increase all parameters. The most optimum condition is plastic pyrolysis oil combustion using steam-atomizing burner at 9 bar steam pressure, which consumes 28 litre of fuel and yields 57% of pyrolysis oil.

Modeling of the process of peeling jerusalem artichoke in order to determine parameters for conducting production process

We proved the need to create equipment for the implementation of a combined process of peeling the tubers of Jerusalem artichoke. A combined peeling process is proposed, which is based on a combination of thermal and mechanical effects on the peeled product. An experimental installation was designed to study the process of thermal treatment of Jerusalem artichoke. It is proven that an increase in steam pressure and duration of the process of thermal treatment lead to the increase in depth of the thermal treatment of the surface layer of Jerusalem artichoke and reduce the efforts required to separate the rind from the tuber. We determined that an increase in duration of the process of mechanical post-peeling increases the percentage of peeled tubers of Jerusalem artichoke, but results in growing losses of raw material. It was established that reducing the effort required to separate the rind of Jerusalem artichoke at thermal treatment makes it possible to reduce duration of the process of mechanical post-peeling. We determined that an increase in depth of the thermal treatment of the surface layer of Jerusalem artichoke leads to increasing losses of raw material. It was proven that the tubers of Jerusalem artichoke, which have a longer storage period, require an increase in duration of the process of their mechanical post-peeling to ensure the required quality of peeling. We determined rational parameters of the combined process of peeling Jerusalem artichoke, which enable to significantly intensify and mechanize the peeling process, to reduce losses of raw material and to improve quality of peeling

Research on the variation law of heating temperature field and the effective energy utilization rate of a steam coil for the floating roof tank

ABSTRACTAs per the way of heat transfer and its main characteristics for oil tank, the theoretical model of steam coil heating in large oil storage tanks was established. The Visual Basic language was applied for calculating the temperature field of crude oil in the heating process by the trial method procedure, and the variation law of temperature field and the energy effective utilization rate of oil tank could be obtained. Results show that the temperature of crude oil and the energy effective utilization rate became higher with the increase of the ambient temperature, steam pressure, and the reduction of storage liquid level. The temperature of crude oil near the steam coil became higher with the increase of steam pressure. The oil temperature at the tank outlet presented periodic change, which was affected simultaneously by the steam pressure and the ambient temperature.

Effect of particle size on the hydrothermal stability of zeolite beta

The effects of particle size, steam pressure, temperature, and duration on the hydrothermal stability of zeolite beta were studied using the Taguchi orthogonal design. The particle size, crystallinity, textural properties, acidity, and framework structure of the zeolite beta were compared before and after hydrothermal treatment. The results showed that the hydrothermal stability of zeolite beta increased with particle size decrease, and decreased with increase of steam pressure and temperature. No significant changes in particle sizes and morphologies were observed for zeolites with particle sizes between 100 nm and 500 nm, while an obvious aggregation was identified for the nano-sized sample. The total surface areas and acidity of all treated zeolites were reduced by hydrothermal treatment. After hydrothermal treatment, obvious realumination was observed for all zeolites.

Effects of steam explosion on the chemical composition and rumen degradability of rice (Oryza sativa L.) straw

AbstractChanges in the chemical composition and in vitro degradability of rice (Oryza sativa L.) straw were examined for effects of steam explosion applied at 12, 16, 20, 24, and 28 kgf/cm2 pressure on rice straw. Physical breakdown of the straw with treatment was observed on most fractions of the particle size. These treatments also decreased (P < 0.05) organic matter and cell wall constituents, such as organic cell walls and neutral detergent fiber contents in the straw, as determined by enzymatic and detergent procedures. In contrast, the acid detergent lignin and acid detergent fiber contents increased (P < 0.05) with increasing steam pressure. The ultraviolet absorbance spectra of water‐soluble extracts in 28 kgf/cm2‐treated straws showed a maximal peak of 0.91 and a shoulder peak of 0.45 around 280 nm and 320 nm, respectively, increasing the maximal absorbance in accordance with the increase in steam pressure. Thus, at the lowest steam pressure, the microbial degradation of rice straw was increased as shown by the results of gas fermentation and volatile fatty acid production. Results in the present study indicate the possibility of improvement of nutritive value of cereal straw using a mild steam explosion treatment, compared to high steam conditions which can dangerously increase insoluble residual substances toxic to rumen microbes in the exploded roughages.

PF-fired supercritical power plant

Pulverized fuel firing is the dominant application of supercritical steam cycles. This has been driven by the aims of efficiency improvement and reduction in environmental emissions. The sensitivity of supercritical steam plant to operating conditions is reviewed and the improvements in operating plant efficiency achieved through increase in steam pressure and temperatures and other factors such as auxiliary power demand is illustrated. Steam temperatures have increased by about 40°C during the 1990s and this, together with an increase in main steam pressure and cycle improvement, have led to a net efficiency of 45 per cent (reduced to UK conditions) for the state-of-the-art plant at present. Plants with still more advanced conditions are under construction or are planned, with the prospect of plant efficiency of 50 per cent in the future. This will rely on continued improvement in materials and is supported by a number of European programmes. Some main difficulties in the design of boilers with advanced temperatures, in particular steam temperature at the furnace outlet, furnace tube arrangement, and materials for superheater and reheater outlet sections, are discussed and the state of advanced steam turbines is reviewed. The operational availability of the supercritical plant, at least in Europe, has improved such that it is little different to the subcritical plant. Similarly, significant improvements have been made in controlling emissions by refinement of flue gas clean-up systems and combustion technology.

Low energy steam explosion treatment of plant biomass

AbstractThe rational operational condition for maximizing the pretreatment effect on plant biomass while minimizing heat required was investigated. Eucalyptus globulus chips were used to evaluate the operational method for the most efficient conversion of plant biomass into useful materials by steam explosion. The energy consumption required to carry out the steam explosion was calculated by considering the mass balances of the water, the wood component, and the heat balance in the steam explosion apparatus. The energy consumption increased significantly with the increase of steam pressure and steaming time, and decreased rapidly with increase of the thickness of the heat‐insulating material in the steam explosion apparatus. The amount of methanol‐soluble lignin, a low molecular weight lignin, was measured experimentally under various operational conditions such as steam pressure and steaming time. The steam explosion at the steam pressure of 3.9 MPa and steaming time of 1.1 min was the most effective method for maximizing the delignification with low energy consumption.© 2001 Society of Chemical Industry

Rupture of Pit Membranes in Sugi (Cryptomerica japanica D. Don) Logs by a Smoke Heating System with Increased Far-Infrared Radiation

Summary A special furnace for smoke-heating logs, with increased far-infrared radiation (FIR), was produced to improve the wood quality. Green sugi (Cryptomeria japonica D.Don) logs were smoke-heated with the direct use of this system. In a short time, this process increased the temperature inside the logs up to 80–100 °C uniformly, without any damage to the wood. The great increase in steam pressure inside the log resulted in the rupture of pit membranes (PMs) with a high frequency, leading to a decrease in the moisture contents of the logs. It was found that when a temperature of 80 °C is attained inside the log, the rupture of PMs occurs. The rupture proceeds from the outer sapwood towards the pith, accompanied by the radiation heat transfer within the log. By the rupture of PMs, smoke-heated sugi wood showed a large improvement in permeability.

Saccharification and alcohol fermentation in starch solution of steam-exploded potato.

Steam explosion pretreatment of potato for the efficient production of alcohol was experimentally studied. The amount of water-soluble starch increased with the increase of steam pressure, but the amounts of methanol-soluble material and Klason lignin remained insignificant, regardless of steam pressure. The potatoes exploded at high pressure were hydrolyzed into a low molecular liquid starch, and then easily converted into ethanol by simultaneous saccharification and fermentation using mixed microorganisms: an amylolytic microorganism, Aspergillus awamori, and a fermentation microorganism, Saccharomyces cerevisiae. The maximal ethanol concentration was 4.2 g/L in a batch culture at 15 g/L starch concentration, and 3.6 g/L in a continuous culture fed the same starch concentration. In the fed-batch culture, the maximal ethanol concentration increased more than twofold, compared to the batch culture.

ボイラ混相流技術のあゆみ

The multiphase technology in power plant boiler during last ten years in Japan have been reviewed. The most important events on utility boiler are the appearance of coal fired supercritical sliding pressure operation boiler, the increase in steam pressure and temperature for higher plant efficiency, and the increase in number of gas turbine combined plants. Concerning these events, some key technology were developed in multiphase field. The detailed study on boiling heat transfer in rifled tube realized the vertical tube type boiler, which had more simple furnace wall structure than the spirally wound type ones. The ultra supercritical pressure boiler achieved 5% higher efficiency than the normal pressure ones. The natural circulation waste heat boiler with horizontal evaporating tubes, which enabled low cost construction, was designed under attentive thermal and hydraulic studies, and successfully started to operate. The condensing heat transfer of ammonia-water mixture was investigated and the high efficiency of the mixture cycle was demonstrated through test plant operation. Regarding fuel, coal oil mixture, coal water mixture, and orimulsion were introduced. For clean and efficient usage of coal, PFBC and IGCC are expected as the important future power generation system.

Comparison of Vapor Phase and Liquid Phase Oxidation of Ethylene to Acetaldehyde with Palladium Chloride-Active Charcoal Catalyst

Comparative studies on the vapor phase and liquid phase oxidation of ethylene were made with palladium chloride-active charcoal catalyst. The catalyst activity in the vapor phase reaction was higher than that in the liquid phase reaction. Acetaldehyde was obtained with high selectivity in both phases. The rate of acetaldehyde formation in the vapor phase was accelerated by the increase in steam pressure and was suppressed by the rise in the reaction temperature while the rate in the liquid phase reaction was accelerated by the rise in the reaction temperature. Aqueous hydrogen chloride solution of about 0.1N was effective as a reaction medium to keep the catalyst activity constant. Contrary to the vapor phase reaction the rate in the liquid phase reaction decreased with the increase in partial pressure of oxygen.

Oxidative Dehydrogenation of n-Butenes over Supported Metallic Palladium Catalysts

N-Butenes were oxidatively dehydrogenated to 1, 3-butadiene in vapor pha e over supported metallic palladium catalysts. The effective temperature range of the reactipn was about 140 to 200C. Major by-products were n-butene isomers small amount of carbon, dioxide and methyl vinyl ketone. AEI n-butene isomersyielded 1, 3-butadiene by this reaction. The order of reactivity was 1-C4Hs trans-2- C4Hs cis- 2-C4Hs. Among several supports, porous glass gave the. best activity, but a of carbon dioxide was als6 formed. When 1 wt oPdonr alumina catalyss was eT at 170 C, one pass yield of butadiene and carbon dioxide was 6.7% and O.46 based on 1-butene, respectively.The oxidative dehydrogeneation proceeded rapidly even in the presence ef small amount of oxygen, while the isoMerezation wassignificantly suppressed by xyge4.The arpognt of 1, 3 bufaVdiehe formed i ncreased with the increase in steam pressure but the isomerized products decreaed.The active intermediate is believed to be z-allyl complex and the followingreaction scheme is proposed.

Some Factors Influencing the Capacity of the Atmospheric Drum Drier

Summary Some of the possible factors responsible for variations in the capacity of atmospheric drum driers are suggested. A standardized method of procedure was set forth for the operation of the drier. The influence on the capacity of the drier on variations from this procedure are reported. Under standardized or normal operation it was stated that the capacity of the drier was from 58 to 60 pounds per hour. Drying of cold milk (50 to 60° F.) resulted in a decrease of 8 per cent in the capacity of the machine. By preheating skimmilk to 185° F., an increase in the capacity of the machine of 18 per cent was secured. It was noted that 26 to 28 per cent more dry skimmilk resulted per hour when skimmilk was applied to the drums at 180 to 185° F. than when skimmilk was applied on the machine in a cold (50 to 60° F.) state. The level at which the skimmilk is maintained over the drums was shown to materially affect the capacity of the drier. In one instance the capacity of the machine was reduced to 32 pounds per hour when a low level was maintained, and in another, when a high level was used, there was a yield of 72 pounds of dry skimmilk per hour, a difference of 40 pounds per hour. The influence on capacity of the steam pressure in the drums and the speed of the machine was studied. With an increase in speed of drums to 36 r. p. m. and an increase in steam pressure in the drums to 85 pounds, the capacity of the machine was 85 pounds of dry skimmilk per hour. Regardless of the temperature of the milk when applied to the drums, the increased speed and steam pressure resulted in increased capacity of the machine. The greatest capacity was secured, however, when the temperature of the milk was applied at the higher temperature (185° F.) using a high speed of machine and high (85 pounds) steam pressure. The most marked influence on the capacity of the drier was noted when concentrated skimmilk containing 30 per cent solids was dried. When cold (40° F.) concentrated skimmilk was applied to the drums operated at 34 r. p. m. a capacity of 70.2 pounds of dry skimmilk per hour resulted. By reducing the speed of the machine to 20 r. p. m. and applying milk at 180° F. to the drums, a capacity of but 73.2 pounds of dry skimmilk resulted. By using the same steam pressure, increased speed of drums up to 36 r. p. m., and applying concentrated milk at 180° F., the capacity of the machine was increased to 130 pounds per hour, or 116 per cent increase over that secured under the standardized method adopted. Though some variation was observed in the moisture content of dry milks produced on the drum drier, it was not possible to correlate variations in moisture of dry milk with the rate at which dry milk was produced from the dryer. With milk of uniform freshness it was evident that variance of the capacity of the drier had no effect on the amount of dispersion of dry milk when reconstituted with water.

Heat Transmission From Condensing Steam to Water in Surface Condensers and Feedwater Heaters

Abstract New experimental data are presented for single-tube water heaters supplied with exhaust steam. These, together with various data from the literature, are analyzed by the graphical method of E. E. Wilson, by means of which the overall resistance to heat transfer, 1/U, may be successfully resolved into its component parts. Furthermore, by employing a coefficient of 2000 for the steam side, and by using the equation of McAdams and Frost for the water-side coefficient, it is possible to predict the value of U for various water velocities and temperatures. These predicted values compare closely with published test data, both for vacuum condensers and feedwater heaters operated with exhaust steam, covering a range of sizes from 80 to 50,000 sq. ft. For abnormal amounts of air or scale, proper allowances should be made by applying the resistance concept. The equation previously published for the heat transfer on the water side is found to be satisfactory for vacuum condensers and exhaust heaters. However, in analyzing laboratory data for single-tube apparatus heated by steam materially above atmospheric pressure, it was found that this equation gave unduly conservative results, the discrepancy increasing with increase in steam pressure. This may be due to the boiling of the water on the inner wall of the pipe, to the evolution of dissolved air, etc. Fortunately, since commercial tubular apparatus are usually operated either under vacuum or with exhaust steam, this complication is of minor importance in plant practice.