scholarly journals Study on the Critical Value of Residual Gas Content Based on the Difference of Adsorption Structure between Soft and Hard Coal

ACS Omega ◽  
2021 ◽  
Author(s):  
Minmin Li ◽  
Weimin Liang ◽  
Haixiao Lin ◽  
Gaowei Yue
Keyword(s):  
Critical Value ◽  
Gas Content ◽  
Hard Coal ◽  
Adsorption Structure ◽  
Residual Gas ◽  
The Difference

Production of quicklime from Ashaka limestone through calcination process

2021 ◽  
Vol 1 (2) ◽  
pp. 041-048
Author(s):  
Benson Chinweuba Udeh
Keyword(s):  
Particle Size ◽  
Critical Value ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Particle Sizes ◽  
Calcination Process ◽  
Process Effects ◽  
Effects Of Temperature ◽  
The Difference ◽  
The Relationship

This study is on the production of quicklime from Ashaka limestone through calcination process. Effects of temperature, particle size and time on quicklime yield were determined. The experiment was carried out at temperatures of 800, 900, 1000, 1100 and 1200 0C, particle sizes of 80mm, 90mm, 100mm, 300mm and 425mm and times of 0.5hr, 1hr, 2hrs, 3hrs and 4hrs. Analyses of the results showed that quicklime was successfully produced from Ashaka limestone through the calcination process. Quadratic model adequately described the relationship between quicklime yield and calcination factors of temperature, particle size and time. Recorded model F-value of 134.35 implies that the model is significant. The predicted R² of 0.9597 is in reasonable agreement with the adjusted R² of 0.9844; the difference is less than the critical value of 0.2. Optimum yield of 73.48% was obtained at optima operating conditions; temperature of 1000 0C, particle size of 90 µm and time of 3 hrs.

Effect of Saturation Degree on Concrete Deterioration due to Freeze-Thaw Action

2011 ◽  
Vol 477 ◽  
pp. 404-408 ◽  
Author(s):  
Wen Cui Yang ◽  
Yong Ge ◽  
Bao Sheng Zhang ◽  
Jie Yuan
Keyword(s):  
Frost Resistance ◽  
Water Pressure ◽  
High Water ◽  
Frost Damage ◽  
Critical Value ◽  
Cold Weather ◽  
Saturation Degree ◽  
Freeze Thaw ◽  
Air Content ◽  
The Difference

Freezing-thawing durability of cement concrete is extremely important in cold weather, to better understand mechanism of frost damage and air-entraining，saturation degree of pores in concrete and its relation with frost resistance were studied in this paper. Concrete specimens with different saturation degree from 0 to 100% were prepared used a sealed tin with a high water pressure pump. Then these specimens were subjected to six freezing-thawing cycles and the relative dynamic modulus of elasticity was examined. The results showed that critical saturation degree of concrete with water- binder ratio of 0.30 and 0.47, air content of 1%, 4% and 6% were from 0.60 to 0.80. When its saturation degree exceeded the critical value, concrete was deteriorated significantly after only six freeze-thaw cycles. The critical saturation degree was mainly related to the air content of concrete mixture, and it decreased with the increasing of air content. The difference between the saturation degree and the critical value can be used to evaluate potential frost resistance of concrete, and its result was consistent with the result of frost tests very well.

scholarly journals A Subglacial Boundary-layer Regelation Mechanism

1990 ◽  
Vol 36 (124) ◽  
pp. 263-268 ◽  
Author(s):  
E.M. Shoemaker
Keyword(s):  
Boundary Layer ◽  
Heat Input ◽  
High Water ◽  
Low Pressure ◽  
Critical Value ◽  
High Water Content ◽  
Overburden Pressure ◽  
Basal Ice ◽  
The Difference ◽  
Linear Nature

AbstractHeat input to basal ice at subglacial low-pressure regions, such as exist on the lee side of bed bumps including regions of ice-bed separation, is shown to melt basal ice internally in a narrow boundary layer at most centimeters thick. Before ice at the ice-bed interface can begin to melt, the heat input Q must exceed a critical value Q*. Q* increases rapidly with an increase in the difference ΔΡ between the nominal (global) overburden pressure and the magnitude of the (local) normal stress acting between the ice and bed or ice and water pocket. Because of the non-linear nature of the flow law, the thickness of the boundary layer decreases rapidly with increasing ΔΡ. The ice in the boundary layer is likely to be soft with a high water content. Under certain conditions, a regelation cycle may exist between the boundary layer and the water in a subglacial cavity. The boundary layer is sufficiently narrow that the processes can reach steady state while ice traverses subglacial low-pressure regions of length the order of 0.01–0.1 m. The regelation phenomenon may preserve or aid the formation of narrow debris-rich ice layers at the base of temperate glaciers.

Respiratory mechanics in the anesthetized rat

1978 ◽  
Vol 45 (2) ◽  
pp. 255-260 ◽  
Author(s):  
Y. L. Lai ◽  
J. Hildebrandt
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Esophageal Pressure ◽  
Gas Content ◽  
Lung Capacity ◽  
Consistent Change ◽  
Residual Capacity ◽  
Wall Compliance ◽  
The Difference ◽  
Body Plethysmograph

Functional residual capacity (FRC) and pressure-volume (PV) curves of the lung, chest wall, and total respiratory system were studied in 15 anesthetized rats, weighing 307 +/- 10 (SE) g. Pleural pressure was estimated from the esophageal pressure measured with a water-filled catheter. The FRC determined by body plethysmograph was slightly and significantly larger than FRC determined from saline displacement of excised lungs. The difference may be accounted for by O2 uptake by lung tissue, escape of CO2 through the pleura, and abdominal gas. Paralysis in the prone position did not affect FRC, and abdominal gas content contributed only slightly to the FRC measured by body plethysmograph. Values of various pulmonary parameters (mean +/- SE) were as follows: residual volume, 1.26 +/- 0.13 ml; FRC, 2.51 +/- 0.20 ml; total lung capacity, 12.23 +/- 0.55 ml; compliance of the lung, 0.90 +/- 0.06 ml/cmH2O; chest wall compliance, 1.50 +/- 0.11 ml/cmH2O; and respiratory system compliance, 0.57 +/- 0.03 ml/cmH2O. The lung PV curve did not show a consistent change after the chest was opened.

scholarly journals Effect on the bactericidal device for decontamination the air microorganisms in poultry house on the content of toxic gases

2020 ◽  
Vol 10 (1) ◽  
pp. 24-29
Author(s):  
A. P. Palii ◽  
O. V. Nanka ◽  
Y. O. Kovalchuk ◽  
A. O. Kovalchuk ◽  
V. S. Kalabska ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ultraviolet Irradiation ◽  
Cold Season ◽  
Gas Content ◽  
Poultry House ◽  
Air Contamination ◽  
Toxic Gases ◽  
Application Techniques ◽  
The Difference ◽  
Rational Construction

Litter in the poultry house is a source of toxic gases (ammonia, hydrogen sulphide and carbon dioxide), dust, and is a favourable place for the life and reproduction of microorganisms and helminths. The number of these secretions in the poultry house depends on many factors: the sanitary status of the poultry house, the species, the age of the birds, the microclimate, the season, feeding conditions, and so on. The purpose of the research was to substantiate the rational construction and modes of operation of the device for the decontamination of microorganisms in the air of the poultry house on the basis of the use of sources of ultraviolet irradiation. The necessity of development and application techniques for cage batteries with a litter removal belt system which provide reduction of microbial contamination of air in poultry houses and the content of harmful gases in it have been substantiated. The device was developed and the effective mode of disinfection of the air of the poultry house in the collector air duct of the litter drying system based on the use of sources of ultraviolet irradiation was determined. The application of the bactericidal device made it possible to reduce microbial air contamination on the 1st day of accumulation of the litter during the cold season - by 2.6 times, in the transitional season - by 2.1 times; on 5th day, the accumulation of the litter decreased by 3.0 and 2.3 times, respectively. During the operation of the air irradiation system, the content of toxic gases in it decreased compared to the period when the air was not treated with the ultraviolet irradiation - ammonia by 19.7% and carbon dioxide by 5.9%. The absolute values of microbial air contamination in the poultry house and the toxic gas content in the transitional season were lower than in the cold season, due to the higher indoor air exchange and the increase of clean outside air in the proportion. The difference in microbial air contamination between the basic and the proposed variants in the cold and transitional seasons was statistically significant.

scholarly journals Study on the Origin and Fluid Identification of Low-Resistance Gas Reservoirs

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zhou Yuhui ◽  
Hu Qingxiong ◽  
Liu Wentao ◽  
Wu Zhiqi ◽  
Yan Yule ◽  
...  
Keyword(s):  
Technical Problem ◽  
Laboratory Data ◽  
Gas Content ◽  
Formation Mechanisms ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Fluid Identification ◽  
Low Resistance ◽  
Neutron Porosity ◽  
The Difference

The Wu 2 section of the Ke017 well block is a low-resistance gas reservoir with ultralow porosity and low permeability. The comprehensive analysis of rock lithology, physical properties, sedimentary characteristics, and gas content demonstrated that the development of micropores in illite/smectite dominated clay minerals together with the resulted additional conductivity capability and complex reservoir pore structures, as well as the enrichment of self-generating conductivity minerals like zeolites and pyrite which were the formation mechanisms of low-resistance gas layers in the Wu 2 section. A low-resistance gas reservoir has poor physical property, and it is difficult to distinguish the oil layer from the dry, gas, or water layers. In this paper, based on well/mud logging data and laboratory data, by taking advantages of the “excavation effect” of neutron gas and the dual-lateral resistivity difference between different depths, we successfully established a set of low-contrast log response methods for the identification and evaluation of oil layer and formation fluids. For a gas layer, the difference between neutron porosity and acoustic (or density) porosity is smaller than 0 and the difference in dual-lateral resistivity is greater than 0. For a water layer, the neutron porosity is similar to the acoustic (or density) porosity and the dual-lateral resistivity difference will be less than 0. While for a dry layer or a layer with both gas and water, the difference in porosity as well as dual-lateral resistivity is very small. The proposed method effectively solves the technical problem of oil layer and formation fluid identification in low-resistance gas reservoirs.

Reactive Power Compensation Method of HVDC Commutation Failure

2014 ◽  
Vol 536-537 ◽  
pp. 1510-1513
Author(s):  
Xiao Ming Wang ◽  
Qi Zhang ◽  
Bin Qian
Keyword(s):  
Reactive Power ◽  
Voltage Drop ◽  
Critical Value ◽  
Reactive Power Compensation ◽  
Transmission System ◽  
Critical Voltage ◽  
High Voltage Direct Current ◽  
Commutation Failure ◽  
The Difference ◽  
Bus Voltage

In the high-voltage direct current transmission system, the difference value between the landing phase voltage and DC transmission system commutation failure of the critical voltage drop value, as system occurred in the critical value of commutation failure. When commutation voltage lower than the critical value would reduce arc Angle, caused by commutation failure。Therefore, by using the method of reactive power compensation to keep converter bus voltage stability, can avoid commutation failure.

ECONOMY OF TIME IN LABORATORY DISTILLATION

1931 ◽  
Vol 5 (4) ◽  
pp. 455-465
Author(s):  
D. F. Stedman
Keyword(s):  
Methyl Alcohol ◽  
Critical Value ◽  
Complete Separation ◽  
Volatile Constituent ◽  
Reflux Ratio ◽  
Correction Factors ◽  
Boiling Points ◽  
Efficient Column ◽  
The Difference ◽  
Theoretical Amount

The mathematics of fractional distillation of ideal mixtures has been condensed, so that the most economical "reflux ratio" for any such mixture may be decided at once.Particular use is made of the "critical reflux ratio" for any mixture, above which even an infinite column cannot obtain complete separation; and the relation of this critical value to the most economical value for any particular case is given.Some of the conclusions with respect to the infinite column were tested by means of a mixture of methyl and ethyl alcohols using a particularly efficient column. It was found that the vapor produced in the still contained slightly more than the theoretical amount of methyl alcohol, and the magnitude of such error is illustrated from previous work on glycerine solutions.The results are given in the form of a graph of the "critical reflux ratio" for the case where the most volatile constituent boils at 100 °C., and the difference between the boiling points varies from 0.25 °C. to 32 °C., the concentration of the most volatile constituent also being included from 0.001 to 1.0.A table of correction factors is also given, showing the factor by which the "critical reflux ratio" should be varied to produce the greatest economy of time for any particular case.

scholarly journals Study on the Impacts of Capillary Number and Initial Water Saturation on the Residual Gas Distribution by NMR

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2714
Author(s):  
Tao Li ◽  
Ying Wang ◽  
Min Li ◽  
Jiahao Ji ◽  
Lin Chang ◽  
...  
Keyword(s):  
Capillary Number ◽  
Water Saturation ◽  
Transverse Relaxation Time ◽  
Spontaneous Imbibition ◽  
Trapping Efficiency ◽  
Gas Distribution ◽  
Initial Water ◽  
Capillary Trapping ◽  
Residual Gas ◽  
The Difference

The determination of microscopic residual gas distribution is beneficial for exploiting reservoirs to their maximum potential. In this work, both forced and spontaneous imbibition (waterflooding) experiments were performed on a high-pressure displacement experimental setup, which was integrated with nuclear magnetic resonance (NMR) to reveal the impacts of capillary number (Ca) and initial water saturation (Swi) on the residual gas distribution over four magnitudes of injection rates (Q = 0.001, 0.01, 0.1 and 1 mL/min), expressed as Ca (logCa = −8.68, −7.68, −6.68 and −5.68), and three different Swi (Swi = 0%, 39.34% and 62.98%). The NMR amplitude is dependent on pore volumes while the NMR transverse relaxation time (T2) spectrum reflects the characteristics of pore size distribution, which is determined based on a mercury injection (MI) experiment. Using this method, the residual gas distribution was quantified by comparing the T2 spectrum of the sample measured after imbibition with the sample fully saturated by brine before imbibition. The results showed that capillary trapping efficiency increased with increasing Swi, and above 90% of residual gas existed in pores larger than 1 μm in the spontaneous imbibition experiments. The residual gas was trapped in pores by different capillary trapping mechanisms under different Ca, leading to the difference of residual gas distribution. The flow channels were mainly composed of micropores (pore radius, r < 1 μm) and mesopores (r = 1–10 μm) at logCa = −8.68 and −7.68, while of mesopores and macropores (r > 10 μm) at logCa = −5.68. At both Swi= 0% and 39.34%, residual gas distribution in macropores significantly decreased while that in micropores slightly increased with logCa increasing to −6.68 and −5.68, respectively.

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