Inherent moisture

To convert from kJ /kg to Btu/lb, multiply by 0.4302 moist mineral -m a tter-free basis, ie, contains inherent moisture but not water visible on the surface. 

The moisture in coal consists of inherent moisture, also called eqm-librium moisture, and surface moisture. Free moisture is that moisture lost when coal is air-dried under standard low-temperature conditions. 

This technology has already been described. Some general characteristics The gasifier is a two-stage pressure shell lined with refractory material in which coal to be gasified is injected as a preheated slurry. The dry coal concentrations in the slurry range from 50 to 70 wt%, depending on the inherent moisture and quality of the feed. Part of the... 

Cellulosics are inherently moisture- and UV-sensitive, requiring efficient stabilization. Cellulose acetate is particularly sensitive to water and weathering. 

COAL. Containing more than 50% (weight) and 70% (volume) of carbonaceous material, including Inherent moisture, coal is a readily combustible rock. Coal was formed from the compaction and induration of variously altered plant remains similar lo those found in peal. Coal was formed during earlier geological periods, the process of formation acting slowly over extremely long periods of lime. Coal is not a uniform substance, but reflects the conditions of its formation. These include ... 

Moist refers to coat containing its natural inherent moisture, but not including visible water on the surface of llte coal. 

Moisture in coal takes three forms (l)free or adherent moisture, essentially surface water (2) physically bound or inherent moisture (thai moisture held by vapor pressure and other physical processes) and (3) chemically bound water (water of hydration or combined" water). The ASTM defines total moisture as a loss in weight in an air atmosphere under rigidly controlled conditions of temperature, time, and air flow. Total moisture represents a measurement of all water not chemically combined. Total moisture is determined by a two-slep procedure, involving air-drying for removal of surface moisture from the gross sample, division and reduction of Ihc gross sample, and determination of residual moisture in the prepared sample. An algebraic calculation is used to obtain the total moisture value. 

Lignite is the lowest rank of coal, often referred to as brown coal, used almost exclusively as fuel for steam-electric power generation. It is brownish black and has a high inherent moisture content, sometimes as high as 45%. The heat content of lignite ranges from 9 to 17 million Btu/ton on a moist, mineral-matter-free basis. 

In the Parr formula for moist, mineral-matter-free calorific value, the moisture basis used is that of the inherent moisture of the coal in the seam (natural bed moisture, capacity moisture) ... 

Air drying removes most of the surface moisture of coal, while a temperature of approximately 107°C (225°F) is needed to remove inherent moisture. At temperatures of approximately 200 to 300°C (392 to 572°F), moisture from the decomposition of organic materials is driven off, but water of hydration requires a considerable amount of energy for expulsion. For example, the water of hydration in clay minerals may require a temperature in excess of 500°C (932°F). However, the issues of decomposition moisture and water of hydration of mineral matter are not usually dealt with in conventional analysis because the temperatures specified in the test methods for moisture determination are well below those needed to remove such moisture. 

The various forms of moisture in coal are described according to the manner in which they are measured by some prescribed standard method. These forms are (1) inherent moisture, (2) surface or free moisture, (3) total moisture, (4) air-dry loss moisture, (5) residual moisture, (6) as-received moisture, (7) decomposition moisture, and (8) water of hydration of mineral matter. 

Inherent or equilibrium moisture is used for calculating moist, mineral-matter-free calorific values for the rank classification of high-volatile bituminous coals. It is also used for estimating free or surface moisture, since total moisture is equal to the sum of the inherent moisture and the free moisture and is considered the inherent moisture of the coal as it occurs in the unexposed seam, where the relative humidity is probably near 100%. However, due to physical limitations, equilibrium moisture determinations are made at 96 to 97% relative humidity and used as inherent moisture values. 

Surface moisture is obtained by subtracting equilibrium moisture from total moisture. However, there is no sharp dividing line between inherent moisture and surface moisture. The measurement of inherent moisture depends on the fact that its vapor pressure is less than that of surface moisture. Drying, pulverizing, dust-proofing, and the general handling of coal all depend on surface moisture... 

Inherent moisture moisture that exists as an integral part of the coal in its natural state, including water in pores but not that present in macroscopically visible fractures (ASTM D-388 ASTM D-1412). 

Gardner and Widstoe (1921) made attempts to develop a general equation. They assumed an ideal soil to be one in which the capillary potential was a linear function of the reciprocal of the moisture-content (after Buckingham, 1907), and that the inherent moisture conductivity is independent of the moisture-content. These assumptions are necessary for mathematical reasons. For downward flow through sand, whose surface is kept saturated, the equation connecting the time t and distance from the surface L was as follows ... 

The Calcination of the Philosophic Stone is the highest purification it receives the inherent moisture, restores the natural warmth, and introduces dissolution. 

According to the recent literature, the principal ash-forming inorganic constituents of agricultural biomass are alkali metals, and silicon. The former are in the form of inorganic salts, dissolved in the inherent moisture, chemically linked to carboxylic or other functional groups, or as complex ions and chemisorbed material. 

There are two kinds of moisture that exist in the coal surface moisture and inherent moisture. Since the CWS is basically a mixture of coal particle and water, the surface moisture of coal does not have too much impact in the GE gasification process. However, a higher surface moisture content means a higher transportation cost. Inherent moisture includes all the moisture that is physically or chemically held within coal. In the CWS preparation step, inherent moisture of the coal plays an important role. With an increase in the inherent moisture, it has been found that the maximum coal concentration possible in a CWS decreases. 

Technically, GE gasifiers can be used to gasify all kinds of coals. However, coals with low inherent moisture (<8wt %), low ash content (<13 wt %), low AFT (<1300 °C), high heating value (>25MJ/kg), and low impurities content (Cl, As, S, etc.) are strongly recommended. 

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