scholarly journals Coal Moisture Variations in Response to Rainfall Events in Mine and Coal-Fired Power Plant Stockpiles—Part 2: Evaporation

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1366
Author(s):  
Quentin Peter Campbell ◽  
Marco le Roux ◽  
Fardis Nakhaei
Keyword(s):  
Laboratory Experiments ◽  
Evaporation Process ◽  
Ambient Conditions ◽  
Moisture Evaporation ◽  
Rainfall Events ◽  
Heating Value ◽  
Surface Evaporation ◽  
Fine Coal ◽  
Coal Beds ◽  
Rate Of Evaporation

Additional moisture added in coal stockpiles due to rain and other climatic processes causes a significant problem worldwide, which leads to not only decrease in the heating value of the coal but also creates an extra efficiency penalty. Therefore, it is important to make some predictions for control of coal moisture within stockpiles after the rainfall. When the rain falls on the stockpile, it either runs off the surface or infiltrates the stockpile. The infiltrated water may evaporate from the surface, drain or stay within the stockpile. The aims of this study (parts 1 and 2) are to describe and compare the changes in coal moisture content following rainfall events. The mechanisms of runoff, infiltration and drainage after rainfall were described in the first paper of this series. In part 2 the influence of coal particle size and ambient conditions on the rate and depth of moisture evaporation within the stockpile is investigated. The laboratory experiments showed cyclic events of adsorbing moisture overnight and desorbing this moisture during the day as part of the coal surface evaporation process. The rate of evaporation from the surface of the fine coal stockpile was faster than the coarse stockpile; however, the coarse stockpile experienced a more efficient evaporation process because of its porous structure. Fine coal beds experienced evaporation only near the surface, while the maximum influencing layer of evaporation is a depth of 0.4 cm below the surface in coarse coal beds.

Production of fuels on the basis of sewage sludge through conditioning using high calorific value fractions

2008 ◽  
Vol 3 (1) ◽  
Author(s):  
Karl-Georg Schmelz ◽  
Anja Reipa ◽  
Hartmut Meyer
Keyword(s):  
Sewage Sludge ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Calorific Value ◽  
Fluidised Bed ◽  
Sludge Treatment ◽  
Heating Value ◽  
Fine Coal ◽  
Used Cars ◽  
Plastic Components

Emschergenossenschaft and Lippeverband operate 59 wastewater treatment plants which produce approx. 100,000 Mg TS of sewage sludge each year. Using sludge pressure pipelines, about 60 % of this sludge are transported to the central sludge treatment plant in Bottrop. The digested sludges are conditioned using fine coal and polymers and are dewatered using membrane filters. By adding coal, the heating value of the sludge is raised which enables autothermal combustion of the dewatered sludges in fluidised bed furnaces at the central sludge treatment plant. In order to replace coal, a fossil fuel, as conditioning agent, experiments were conducted using alternative materials with high heating values. The addition of shredder fluff agglomerates proved to be particularly successful. Shredder fluff agglomerates are a residue from the recycling of used cars and are generated in a multistage process (e.g. Volkswagen-SiCon Process) by separating the light shredder fraction (plastic components etc.) from the total shredder fluff. The fibrous material is outstandingly suitable for improving the dewaterability and for sufficiently raising the heating value of the dewatered sludge in order to enable autothermal combustion. Since first experiments showed very positive results, a full-scale long-term test-run will take place in 2007.

Maintaining Low Exhaust Emissions With Turbocharged Gas Engines Using a Feedback Air–Fuel Ratio Control System

1987 ◽  
Vol 109 (4) ◽  
pp. 487-490 ◽  
Author(s):  
D. W. Eckard ◽  
J. V. Serve´
Keyword(s):  
Control System ◽  
Temperature Control ◽  
Exhaust Emissions ◽  
Ambient Conditions ◽  
Load Range ◽  
Heating Value ◽  
Gas Engine ◽  
Precise Control ◽  
Natural Gas Engine ◽  
Fuel Ratio

Maintaining low exhaust emissions on a turbocharged, natural gas engine through the speed and load range requires precise control of the air–fuel ratio. Changes in ambient conditions or fuel heating value will cause the air–fuel ratio to change substantially. By combining air–gas pressure with preturbine temperature control, the air–fuel ratio can be maintained regardless of changes in the ambient conditions or the fuel’s heating value. Design conditions and operating results are presented for an air–fuel controller for a turbocharged engine.

The Ethanol-Water Humidification Process in EvGT Cycles

2004 ◽  
Author(s):  
Marcus Thern ◽  
Torbjo¨rn Lindquist ◽  
Tord Torisson
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Production ◽  
Test Facility ◽  
Level Energy ◽  
Water Mixture ◽  
Evaporation Process ◽  
Heating Value ◽  
Lower Heating Value ◽  
Lower Heating

Ethanol from bio-products has become an important fuel for future power production. However, the present production technology is rather expensive. This paper focuses on how to lower the production cost of ethanol extraction from mash, and to use the ethanol as a primary fuel in gas turbines for heat and power production. Today, ethanol is produced during distillation by supplying energy to extract the ethanol from the mash. Using the evaporation process in the evaporative gas turbine to extract the ethanol from the mash before the distillation step, a lot of energy can be saved. In the evaporation process, the ethanol is extracted directly from the mash using energy from low-level energy sources. The evaporation technology is therefore expected to reduce the cost for the ethanol production. Simultaneous heat and mass transfer inside the ethanol humidification tower drives a mixture of ethanol and water into the compressor discharge air. To investigate the evaporation of a binary mixture into air at elevated pressures and temperatures, a test facility was constructed and integrated into the evaporative gas turbine pilot-plant. The concentration of ethanol in the mash is not constant but depends on the sugar content in the feedstock used in the fermentation process. Tests were therefore conducted at different concentrations of ethanol in the ethanol-water mixture. Tests were also performed at different temperature and flow conditions to establish the influence of these parameters on the lower heating value of the produced low calorific gas. It has been shown that this technology extracts about 80% of the ethanol from the mash. It has also been shown that the composition of the resulting gas depends on the temperatures, flow rates and composition of the incoming streams. The tests have shown that the produced gas has a lower heating value between of 1.8 to 3.8 MJ/kg. The produced gas with heating values in the upper range is possible to use as fuel in the gas turbine without any pilot flame. Initial models of the ethanol humidification process have been established and the initial test results have been used for validating developed models.

scholarly journals Relation between Void Structure and Dewatering in Fine Coal Beds

1960 ◽  
Vol 63 (3) ◽  
pp. 508-512
Author(s):  
Seiichi Tajima ◽  
Yoshio Yamagata ◽  
Shoichiro Tachikawa
Keyword(s):  
Fine Coal ◽  
Coal Beds ◽  
Void Structure

Analysis of the moisture evaporation process during vacuum freeze-drying of koumiss and shubat

2016 ◽  
Vol 53 (5) ◽  
pp. 1571-1578 ◽  
Author(s):  
Azret Utebaevich Shingisov ◽  
Ravshanbek Sultanbekovich Alibekov
Keyword(s):  
Freeze Drying ◽  
Evaporation Process ◽  
Moisture Evaporation

The dynamic evaporation process of the deep eutectic solvent LiTf2N:N-methylacetamide at ambient temperature

2019 ◽  
Vol 21 (22) ◽  
pp. 11810-11821 ◽  
Author(s):  
Yu Chen ◽  
Dongkun Yu ◽  
Li Fu ◽  
Meng Wang ◽  
Dongran Feng ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Deep Eutectic Solvent ◽  
Evaporation Process ◽  
Ambient Conditions ◽  
Three Stages

The dynamic evaporation process of the lithium-based deep eutectic solvent LiTf2N:NMA under ambient conditions can be divided into three stages.

The Influence of Atmospheric and Subsoil Impact on the Evaporation Process During Firefighter’s Events

2021 ◽  
Vol 23 ◽  
pp. 420-433
Author(s):  
Andrzej Polanczyk ◽  
Aleksandra Piechota-Polanczyk ◽  
Małgorzata Majder-Łopatka ◽  
Anna Dmochowska ◽  
Zdzislaw Salamonowicz
Keyword(s):  
Wind Speed ◽  
Tap Water ◽  
Porous Surface ◽  
Evaporation Process ◽  
Surface Evaporation ◽  
Evaporation Intensity ◽  
Porous Surfaces ◽  
Set Up

The influence of sun rays, wind speed, and different type of subsoil on the evaporation process was analyzed. A dedicated experimental set-up for investigation of evaporation process of three liquids (ethanol, petrol and tap water) deposited on glass and sand was created. Results indicated that for porous surfaces wind decreased the amount of evaporated liquids. After substitution of wind with sun rays for porous surface evaporation process increased for ethanol and petrol, respectively. Finally, the influence of both wind and sun rays indicated a 1% and 5% decrease of evaporation intensity for tap water and petrol, respectively. While, a 2% increase of evaporated liquid was observed for ethanol. It was noticed that application of porous surface caused the highest improvement of evaporation process for petrol and tap water, while the lowest for ethanol. Moreover, application of wind together with porous surface increased the intensity of evaporation for all analyzed liquids.

Vegetation carrying capacity of arid regions: on the fraction of rainfall sheltered from surface evaporation

2020 ◽  
Author(s):  
Dani Or ◽  
Peter Lehmann ◽  
Samuel Bickel ◽  
Simone Fatichi
Keyword(s):  
Carrying Capacity ◽  
Arid Regions ◽  
Potential Evapotranspiration ◽  
Rainfall Variability ◽  
Aridity Index ◽  
Arid Lands ◽  
Soil Water Storage ◽  
Annual Rainfall ◽  
Rainfall Events ◽  
Surface Evaporation

<p>Arid lands represent one third of terrestrial surfaces with ecosystems uniquely adapted to water limitations. Arid regions are characterized by low rainfall and sparse vegetation with potential evapotranspiration (ET<sub>0</sub>) exceeding annual rainfall (P) and surface evaporation dominating water losses. The objective was to quantify the fraction of rainwater sheltered from surface evaporation to estimate arid region vegetation carrying capacity. The surface evaporation capacitor (SEC) model was used to quantify surface evaporation from the climatic record of rainfall and potential evaporation. The SEC uses soil-specific active evaporation depth where only rainfall events that exceed its critical capacitance result in leakage into deeper layers. This “leakage” becomes protected from surface evaporation and may support vegetation or inter-annual storage. Focusing on arid regions (aridity index P/ET<sub>0</sub>< 0.2) we illustrate the strong correlation between evaporation-protected rainwater and net primary productivity (NPP) using typical values of water use efficiency. SEC-estimated NPP values were in good agreement with observations and predictions by a state-of-the art ecohydrological model (T&C). Evaporation-protected soil water storage is generated during a few large rainfall events that exceed surface capacitance. This leakage increases with increasing rainfall variability, potentially enhancing vegetation carrying capacity by diverting larger fractions of rainfall from surface evaporation to vegetation-supporting “leakage”. The potential increase in carrying capacity and resulting vegetation cover are greatly influenced by (i) the change in rainfall variability, (ii) soil type, and (iii) surface features that concentrate or divert runoff. We discuss implications of this mechanism for global greening of arid lands and woody plant encroachment.</p>

Gas Turbine Combustor Analysis

1975 ◽  
Vol 97 (4) ◽  
pp. 610-618
Author(s):  
D. A. Sullivan
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Water Injection ◽  
Direct Calculation ◽  
Steam Injection ◽  
Ambient Conditions ◽  
Gas Turbine Combustor ◽  
Heating Value ◽  
Compressor Pressure Ratio ◽  
Machine Speed

The pressure, temperature, and fuel-to-air ratio of a gas turbine combustor vary with ambient conditions, machine speed, and load. Only a few of these parameters are independent. An analysis has been developed which predicts the combustor operating parameters. The analysis includes low heating value fuel combustion, water injection, and three modes of steam injection. The analysis is used to predict the combustor operation for a simple-cycle gas turbine, but it is not restricted to this case. In addition, a simplified analysis is deduced and shown to be surprisingly accurate. Special solutions are presented which permit direct calculation of the firing temperatures, fuel heating value, or air extraction required to achieve a specified compressor pressure ratio. Finally, the analysis is compared with experimental results.

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