Fossil coals. Big encyclopedia of oil and gas
In the composition of coals, along with organic substances, there are mineral impurities, which are usually ballast. To evaluate coals, it is important to know the ratio between these constituent parts... Technical analysis consists in determining moisture (W), ash content (A), yield volatile matter(V), sulfur content (Sb), calorific value (Q) and coke residue.
Humidity reduces the heat of combustion of coal. Coals are divided into three groups: B1 - with a moisture content of more than 40%, B2 - 30-40%, B3 - 30% or less. Humidity is determined by heating to 1050 ° C or by drying in a desiccator over concentrated sulfuric acid. 1% moisture reduces the thermal conductivity of coal by 6 kcal.
Ash content... Ash is a solid non-combustible residue formed from mineral impurities of coal; by weight it is not equal to mineral impurities, because some of them turn into gas and water vapor. Each percentage of ash reduces the productivity of the blast furnace by 2.5%. The permissible ash content for coking coals is less than 10%; with a high ash content, coal preparation is required. The main components that make up ash: oxy-
Si, Al, Fe, Ca, Mq, Na, K; oxides Ti and Mn are of subordinate importance.
Volatile matter release... Refers to the combustible part; during dry distillation, coal partially transforms into volatile substances (CH 4, H, CO, CO 2, etc.). Volatile substances are very valuable. They have the ability to burn, and also form the basis for the production of various chemical products: dyes, plastics, aromatic and explosives.
Coke residue... This is the solid residue that remains after the removal of volatiles, depending on the quality of the coal has different kind... It can be powder - unsintered, sintered, fused or swollen. The caking capacity of coals is expressed in the ability, when heated under certain conditions, to combine into one whole and give a sufficiently strong solid residue with a porous structure - metallurgical type coke. The coals giving the powdery residue are non-caking and are only suitable for energy purposes. Sulfur is a harmful impurity in coals, especially coke coals, which causes an increased consumption of coke when smelting ore and degrades the quality of iron. According to the sulfur content, coals are divided into groups: low-sulfur (up to 1.5%), medium-sulfur (1.5-2.5%), sulphurous (2.5-4%), high-sulfur (more than 4%). The latter are not suitable for use in ferrous metallurgy without preliminary enrichment.
Heat of combustion coal is approximately 24.62 kJ / kg. It is determined by an experimental method - by burning coal in a calorimetric bomb, and by calculation, according to the formulas. Anthracites and lean coals have the highest calorific value.
In many cases, especially when evaluating non-metallic minerals, in addition to the study of technical properties, a chemical analyzes raw materials (refractory and ceramic clays, limestones such as fluxes, kaolin, talc, etc.). For some minerals (foundry sands), particle size analysis is also carried out.
Laboratory work № 3
Determination of the heat of combustion of coals according to their moisture content,
ash content and volatile matter yield
Objective- get acquainted with the methods for determining the main indicators of technical analysis of coals, master the practical skills of working on the appropriate laboratory equipment and study in practice the basics of the accelerated method for evaluating coals.
The laboratory work is complex. It is based on the determination of three main indicators of coal - moisture content, ash content and the release of volatile substances, on the basis of which the lowest heat of combustion of the working mass of coal is calculated, which is the most important indicator of the quality of coal as a power fuel.
The heat of combustion, usually denoted by the symbol, is the amount of thermal energy (hereinafter heat, or heat) released during the complete oxidation of combustible fuel components with gaseous oxygen. In this case, it was assumed that as a result of oxidation reactions, higher oxides are formed and sulfur is oxidized only to, and fuel nitrogen is released in the form of molecular nitrogen. The heat of combustion is a specific characteristic. Hard and liquid fuels refer to a unit of mass, that is, to 1 kg(specific heat of combustion), and for gaseous fuels - to a unit volume (volumetric heat of combustion) under normal physical conditions, that is, under R
= P 0
= 760 mmHg Art. = 1 atm =101325 Pa and
T = T 0 = 273.15 TO (t
= t 0
= 0 ° C). Concerning m 3 under these conditions received the name " normal cubic meter
"And the recommended designation" burrow. m 3". Thus, for gaseous fuels, 1 burrow. m 3. Units of measurement accepted in technical literature: " kJ / kg» (« kJ / nor. m 3") or " MJ / kg» (« MJ / nor. m 3"). In the old technical literature, the units of measurement were “ kcal / kg» (« kcal / nor. m 3"). When converting them into modern units of measurement, it should be remembered that 1 kcal = 4,1868 kJ.
The amount of heat that went to heat the products of complete combustion 1 kg or 1 burrow. m 3 fuel, provided that these products contain condensed water vapor, that is, water is called higher heating value of fuel ... This warmth is referred to as.
If water vapor is not condensed during fuel combustion, then a smaller amount of released heat will be consumed for heating the combustion products by the value of the latent heat of condensation of water vapor (latent heat of evaporation of water). In this case, the heat was called net calorific value of fuel
and denoted as. Thus, the determination does not take into account the heat spent on the evaporation of moisture in the fuel itself and moisture formed during the combustion of hydrogen in the fuel. Accordingly, the quantity is related to how 
.
The composition of coal, like any other solid fuels, is expressed as a percentage by weight (wt%). At the same time, 100% are most often taken:
· The composition of the fuel in working condition (the composition of its working mass), indicated by the superscript " r »:
· Composition in the analytical state (composition of the analytical mass), indicated by the superscript " a »:
· Composition in a dry state (composition of dry mass), indicated by the superscript " d »:
· Composition in dry ash-free state (composition of dry ash-free mass), indicated by the superscript " daf »:
where the mass fractions in the corresponding mass of coal of carbon, hydrogen, combustible sulfur, oxygen, nitrogen, total and analytical moisture, wt. %; A - ash content of the corresponding mass of coal, wt. %.
To determine the heat of combustion of coal, a single standard method is used - the method of combustion in a calorimetric bomb. With this method, a weighed portion of an analytical sample of coal weighing 0.8 ... 1.5 G burned in an atmosphere of compressed oxygen in a hermetically sealed metal vessel - a calorimetric bomb, which is immersed in a certain volume of water. By increasing the temperature of this water, the amount of heat released during the combustion of the sample is established. This gives the heat of combustion of the fuel by the bomb. Due to the fact that the combustion of fuel occurs in quite specific
 |
Rice. Schematic diagram classical calorimeter for determining the heat of combustion of solid fuels
1 - calorimetric bomb; 2 - stirrer; 3 - thermostat cover; 4 - system for ignition of the hinge; 5 - thermometer or a device replacing it; 6 - calorimetric vessel; 7 - thermostat.
conditions (atmosphere of pure oxygen, oxidation of combustible sulfur to SO 3 followed by the formation of nitric acid in condensed moisture, and so on), the value is recalculated to according to the following formula:
where is the heat of formation of sulfuric acid from SO 2
and dissolving it in water, numerically equal to 94,4 kj based on 1% sulfur; - the sulfur content "in the washout of the bomb" is the amount of sulfur that was converted into sulfuric acid during combustion, based on the initial sample of coal, wt. % (it is allowed to use instead of the total sulfur content in the analytical mass of coal if 
(0.8% for brown coal of the Kansk-Achinsk basin, 1.0 for coal and 1.2% for anthracite)
, a 
(15.5 MJ / kg for brown coal of the Kansk-Achinsk basin, 15.7 for bituminous coal and 16.0 MJ / kg for anthracite)
; a
- coefficient taking into account the heat of formation and dissolution of nitric acid, equal to 0.001 for lean coals and anthracites and 0.0015 - for all other fuels
.
Knowing, first determine the highest heat of combustion of the working mass of fuels:
, (2)
where 
=MJ / kg or MJ / normal m 3; 
=
= wt. %.
The coefficient 24.62 in (3) reflects the heat of water heating from
t 0
= 0 ° C to t
= 100 ° C and its evaporation at P 0
= 101325 Pa counting on
1 wt. % water.
The value calculated for the operating state of the fuel corresponds to the actual heat released during its combustion in furnaces, and therefore is widely used in heat engineering calculations. is an integral indicator of the quality of fuels and largely determines their consumer properties.
One of the main features of fossil coals is the ability to decompose (degrade) their organic matter when heated without air access. This heating produces gaseous and vaporous decomposition products called volatiles. After the removal of volatiles from the heating zone, a residue remains, called coke residue, or coke. Since volatile substances are not contained in coals, but are formed when they are heated, then they speak about the "release of volatile substances", and not about their content in coals.
The volatiles yield is understood as the relative mass of volatiles, expressed as a percentage, formed during the thermal decomposition of coal under standard conditions. The release of volatiles is indicated by the symbol V , and the non-volatile (coke) residue - NV .
The vaporous part of volatile substances consists of condensable hydrocarbons, which are a group of oily and resinous substances, which are the most valuable chemical product.
The gaseous part of volatile substances consists of hydrocarbon gases of the limiting and unsaturated series ( CH 4 , C m H n and so on), carbon monoxide and dioxide ( CO , CO 2 ), hydrogen ( H 2 ) etc.
The non-volatile residue consists mainly of carbon and mineral impurities in the form of ash.
The release of volatile substances is one of the main classification parameters of fossil coals. Based on the values of the volatiles yield and the characteristics of the coke residue, the suitability of coals for coking and the behavior of coals in the processing and combustion processes are assessed.
The essence of the standard method for determining the yield of volatile substances consists in heating a weighed portion of an analytical coal sample weighing 1 ± 0.1 g without air access at t = 900 ± 5 ° C within 7 min... The release of volatile substances is determined by the weight loss of the original sample, taking into account the moisture content of the fuel.
The value of the release of volatiles from the analytical sample is calculated by the formula
(4)
where = wt. %; - weight loss of a sample of coal after the release of volatile substances, G; - the mass of the initial sample of coal, G; - moisture content in the initial sample of the analytical coal sample, wt. %;
- the yield of the non-volatile residue from the analytical sample of the test coal,%, is calculated by the formula
The release of volatile substances on the dry ash-free state of coal is determined as follows:
. (6)
Allowable discrepancies between the results of two parallel determinations absolute values should not exceed 0.3 wt. % at wt%; 0.5 mas. % at wt. %; 1.0 wt. % at wt. % .
To determine the yield of volatile substances, use:
Stands for installing crucibles in a muffle furnace made of heat-resistant steel or wire;
Electric muffle furnace with a thermostat with a maximum heating temperature of at least 1000 ° C, having an opening in the front door for free removal of volatiles (if there is no branch tube for removal of these substances) and placement of a control thermocouple and in the rear wall for installing a thermocouple.
The temperature is measured with a stationary thermocouple. From an analytical sample of coal, two weighed portions of coal with a mass of (1 ± 0.01) are taken into pre-weighed crucibles G.. The weighed portion is distributed over the bottom of the crucible in an even layer, lightly tapping the crucible on a clean, dry surface. The crucibles are closed with lids and carefully, with an accuracy of 0.0002 G Weigh the closed crucibles with weighed portions.
The crucibles with coal weighed portions and closed lids are each set on their own support and quickly introduced into the muffle furnace, preheated to t = 900 ± 5 ° C, which is fixed by a stationary thermocouple. The oven door is closed. Exactly 7 min(± 5 sec) the stands with crucibles are removed from the oven and cooled - first in air for 5 min, without removing the lids from the crucibles, and then in a desiccator to room temperature and weighed to the nearest 0.0002 G... The results of all measurements and calculations are entered in Table 1.
The values are calculated by the formula (7), and - by the formula (8):
(7)
(8)
Work order
1. Prepare the necessary tables and carry out the necessary calculations. Record the results in Table 1 and Table 2.
Table 1
Results of determining the yield of volatile substances
| Indicator | Sample 1 | Sample 2 |
| Weight of empty calcined crucible M T, G | ||
| Crucible weight with initial sample of coal M TU, G | ||
| The mass of the initial sample of coal M U = M TU– M T, G | ||
| Crucible weight with non-volatile residue after testing, G | ||
| Weight loss of a sample of coal after test D M U= M TU -M T NV, g | ||
| The release of volatile substances from the test portions of the test coal 1 and 2, wt. % | ||
| The yield of volatile substances from the analytical mass of the test coal, wt. % | ||
| The yield of volatile substances per dry ashless state of the test coal, wt. % |
3. Using the values obtained in laboratory work No. 2 (10.03%), (13.14%) and (30.7% from Table 1), calculate and included in the list necessary indicators technical analysis of coal, and (11.82%) required for the calculation.
4. Considering the brand of coal proposed in the work and using the obtained indicators, determine the value of coal using the following methods.
Method 1. Use the relationship between and suggested
Laboratory work No. 3
Determination of the heat of combustion of coals according to their moisture content,
ash content and volatile matter yield
Objective- get acquainted with the methods for determining the main indicators of technical analysis of coals, master the practical skills of working on the appropriate laboratory equipment and study in practice the basics of the accelerated method for evaluating coals.
The laboratory work is complex. It is based on the definition of three main indicators of coal - moisture content, ash content and the release of volatile substances. 
on the basis of which the net calorific value of the working mass of coal is calculated, which is the most important indicator of the quality of coal as a power fuel.
The heat of combustion, usually denoted by the symbol, is the amount of thermal energy (hereinafter heat, or heat) released during the complete oxidation of combustible fuel components with gaseous oxygen. In this case, it was assumed that as a result of oxidation reactions, higher oxides are formed 
and 
sulfur is oxidized only to 
, and the nitrogen of the fuel is released as molecular nitrogen. The heat of combustion is a specific characteristic. For solid and liquid fuels, refer to a unit of mass, that is, to 1 kg(specific heat of combustion), and for gaseous fuels - to a unit volume (volumetric heat of combustion) under normal physical conditions, that is, under R
= P 0
= 760 mmHg Art. = 1 atm =101325 Pa and
T = T 0 = 273.15 TO (t
= t 0
= 0 ° C). Concerning m 3 under these conditions received the name " normal cubic meter
"And the recommended designation" burrow. m 3". Thus, for gaseous fuels, 1 burrow. m 3. Units of measurement accepted in technical literature: " kJ / kg» (« kJ / nor. m 3") or " MJ / kg» (« MJ / nor. m 3"). In the old technical literature, the units of measurement were “ kcal / kg» (« kcal / nor. m 3"). When converting them into modern units of measurement, it should be remembered that 1 kcal = 4,1868 kJ.
The amount of heat that went to heat the products of complete combustion 1 kg or 1 burrow. m 3 fuel, provided that these products contain condensed water vapor, that is, water is called higher heating value of fuel ... This warmth is referred to as.
If water vapor is not condensed during fuel combustion, then a smaller amount of released heat will be consumed for heating the combustion products by the value of the latent heat of condensation of water vapor (latent heat of evaporation of water) 
... In this case, the heat was called net calorific value of fuel
and denoted as. Thus, the determination does not take into account the heat spent on the evaporation of moisture in the fuel itself and moisture formed during the combustion of hydrogen in the fuel. Accordingly, the quantity is related to how 
.
The composition of coal, like any other solid fuels, is expressed as a percentage by weight (wt%). At the same time, 100% are most often taken:
· The composition of the fuel in working condition (the composition of its working mass), indicated by the superscript " r »:
· Composition in the analytical state (composition of the analytical mass), indicated by the superscript " a »:
· Composition in a dry state (composition of dry mass), indicated by the superscript " d »:
· Composition in dry ash-free state (composition of dry ash-free mass), indicated by the superscript " daf »:
where the mass fractions in the corresponding mass of coal of carbon, hydrogen, combustible sulfur, oxygen, nitrogen, total and analytical moisture, wt. %; A - ash content of the corresponding mass of coal, wt. %.
To determine the heat of combustion of coal, a single standard method is used - the method of combustion in a calorimetric bomb. With this method, a weighed portion of an analytical sample of coal weighing 0.8 ... 1.5 G burned in an atmosphere of compressed oxygen in a hermetically sealed metal vessel - a calorimetric bomb, which is immersed in a certain volume of water. By increasing the temperature of this water, the amount of heat released during the combustion of the sample is established. This gives the heat of combustion of the fuel by the bomb. Due to the fact that the combustion of fuel occurs in quite specific
 |
Rice. Schematic diagram of a classical calorimeter for determining the heat of combustion of solid fuels
1 - calorimetric bomb; 2 - stirrer; 3 - thermostat cover; 4 - system for ignition of the hinge; 5 - thermometer or a device replacing it; 6 - calorimetric vessel; 7 - thermostat.
conditions (atmosphere of pure oxygen, oxidation of combustible sulfur to SO 3 followed by the formation of nitric acid in condensed moisture, and so on), the value is recalculated to according to the following formula:
where is the heat of formation of sulfuric acid from SO 2
and dissolving it in water, numerically equal to 94.4 kj based on 1% sulfur; - the sulfur content "in the washout of the bomb" is the amount of sulfur that was converted into sulfuric acid during combustion, based on the initial sample of coal, wt. % (it is allowed to use instead of the total sulfur content in the analytical mass of coal if 
, a 
); a
- coefficient taking into account the heat of formation and dissolution of nitric acid, equal to 0.001 for lean coals and anthracites and 0.0015 for all other fuels.
Knowing, first determine the highest heat of combustion of the working mass of fuels:
, (2)
where 
=kJ / kg or kJ / normal m3; 
=
= wt. %.
The coefficient 24.62 in (3) reflects the heat of water heating from
t 0
= 0 ° C to t
= 100 ° C and its evaporation at P 0
= 101325 Pa counting on
1 wt. % water.
The value calculated for the operating state of the fuel corresponds to the actual heat released during its combustion in furnaces, and therefore is widely used in heat engineering calculations. is an integral indicator of the quality of fuels and largely determines their consumer properties.
One of the main features of fossil coals is the ability to decompose (degrade) their organic matter when heated without air access. This heating produces gaseous and vaporous decomposition products called volatiles. After the removal of volatiles from the heating zone, a residue remains, called coke residue, or coke. Since volatile substances are not contained in coals, but are formed when they are heated, then they speak about the "release of volatile substances", and not about their content in coals.
The volatiles yield is understood as the relative mass of volatiles, expressed as a percentage, formed during the thermal decomposition of coal under standard conditions. The release of volatiles is indicated by the symbol V , and the non-volatile (coke) residue - NV .
The vaporous part of volatile substances consists of condensable hydrocarbons, which are a group of oily and resinous substances, which are the most valuable chemical product.
The gaseous part of volatile substances consists of hydrocarbon gases of the limiting and unsaturated series ( CH 4 , C m H n and so on), carbon monoxide and dioxide ( CO , CO 2 ), hydrogen ( H 2 ) etc.
GOST R 55660-2013
NATIONAL STANDARD OF THE RUSSIAN FEDERATION
FUEL SOLID MINERAL
Determination of the release of volatile substances
Solid mineral fuel. Determination of volatile matter
OKS 75.160.10 *
OKP 03 2000
_______________
* In IUS 1-2015 GOST R 55660-2013 is given with OKS 75.160.10, 73.040. -
- Note from the manufacturer of the database.
Introduction date 2015-01-01
Foreword
1 PREPARED by the Federal State unitary enterprise"All-Russian Research Center for Standardization, Information and Certification of Raw Materials, Materials and Substances" (FSUE "VNITsSMV") on the basis of its own authentic translation into Russian of the standards specified in paragraph 4
2 SUBMITTED by the Technical Committee for Standardization Russian Federation TC 179 "Solid mineral fuel"
3 APPROVED AND PUT INTO EFFECT by the Order of the Federal Agency for Technical Regulation and Metrology of October 28, 2013 N 1230-st
4 This International Standard is modified with respect to international standards ISO 562: 2010 * "Hard coal and coke - Determination of volatile matter" (ISO 562: 2010 "Hard coal and coke - Determination of volatile matter") and ISO 5071-1: 2013 "Brown coals and lignites - Determination of volatile matter yield in an analytical sample. Part 1. Method with two furnaces "(ISO 5071-1: 2013" Brown coals and lignites - Determination of the volatile matter in the analysis sample - Part 1: Two furnace method ").
________________
* Access to international and foreign documents mentioned here and hereinafter in the text can be obtained by clicking on the link to the site http://shop.cntd.ru
Additional provisions included in the text of the standard to take into account the needs of the national economy are in italics * and set out in the introduction
________________
* In the original paper designations and numbers of standards and normative documents in the section "Preface" are given in regular type, marked with "**" and the rest in the text of the document are in italics. - Note from the manufacturer of the database.
5 INTRODUCED FOR THE FIRST TIME
The rules for the application of this standard are set out in GOST R 1.0-2012 ** (section 8). Information about changes to this standard is published in the annual (as of January 1 of the current year) information index " National standards", and the official text of the changes and amendments is in the monthly information index" National Standards. " v information system general use - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet (gost.ru)
Introduction
Introduction
The release of volatile substances is defined as the weight loss of the sample solid fuel minus moisture when heated without air access under standard conditions.
The test results are relative, therefore, to achieve reproducibility, it is necessary to maintain the constancy of the basic parameters: heating rate, final temperature and heating duration. To reduce oxidation of the fuel sample during heating, the access of oxygen to the sample should be limited. This is achieved by using crucibles with ground or ground-in lids that allow free removal of volatile substances, but prevent the penetration of oxygen.
The equipment and test method allow one or several determinations to be carried out simultaneously in a muffle furnace.
When testing brown coals and lignites, a violent release of volatiles is possible, accompanied by the ejection of solid particles from the crucible, which distorts the determination result. To reduce to a minimum the likelihood of particle carryover from the crucible during heating, special methods are provided: briquetting a sample and / or heating in two furnaces.
The release of volatile substances is one of the classification parameters of bituminous coals.
When determining the yield of volatile substances, the total weight loss due to the decomposition of the organic and mineral masses of coal is taken into account. With a significant ash content of coal, the resulting products of destruction of the mineral mass distort the value of the yield of volatile substances, therefore, if the test is carried out in order to classify coals, their ash content should not exceed 10%. Samples with higher ash content are preliminarily enriched.
Based on the values of the yield of volatile substances and the characteristics of the non-volatile residue, it is possible to roughly estimate the sintering capacity of coals, as well as the behavior of coals in the processes of technological processing and combustion.
V this standard included additional requirements in relation to ISO 562 and ISO 5071-1, reflecting the needs of the national economy, namely:
- in the area of distribution, the types of solid mineral fuels are specified;
- added section 3 "Terms and definitions";
- the characteristics of the non-volatile residue are given (section 9);
- the method of preparation of samples of coals for the purpose of classification of coals is given (subsection 7.2);
- added methods for briquetting the sample (subsection 7.3) and determining the release of volatile substances from the briquetted sample (section 8.5.1);
- the method with preliminary drying of the sample in a crucible has been removed from the text of the standard (ISO 5071-1).
1 area of use
This standard applies to lignites, lignite and bituminous coals, anthracites, oil shale, beneficiation products, briquettes and cokes (hereinafter referred to as fuel) and establishes gravimetric methods for determining the yield of volatile substances.
The general principle for determining the yield of volatile substances is established for all types of solid mineral fuels, and the conditions for determination are different for the group of coal (coal, anthracite, oil shale, coal briquettes, enrichment products) and cokes and for the group of brown coals (lignites, brown coals, brown coal briquettes, processed products).
Note - For a group of brown coals, two alternative methods of preventing the release of solid particles from the crucible are recommended: briquetting the sample and / or heating in two furnaces.
2 Normative references
Throughout this standard, references are made to the following standards:
GOST R 50342-92 Thermoelectric converters. Are common technical conditions(IEC 584-2: 1982)
GOST R 52917-2008 Solid mineral fuel. Methods for determination of moisture in an analytical sample (ISO 11722: 1999, ISO 5068-2: 2007, MOD)
GOST R 53288-2008 * Non-automatic balances. Part 1. Metrological and technical requirements. Tests (OIML R 76-1: 2006 (E), MOD)
________________
* Probably a mistake in the original. Should read: GOST R 53228-2008. - Note from the manufacturer of the database.
GOST 1186-87 Coals of stone. Method for determination of plastometric parameters
GOST 4790-93 The fuel is solid. Determination and presentation of indicators of fractional analysis. General specifications (ISO 7936: 1992, MOD)
GOST 5955-75 Reagents. Benzene. Technical conditions
GOST 9147-80 Porcelain laboratory utensils and equipment. Technical conditions
GOST 10742-71 Brown coals, stone coals, anthracite, oil shale and coal briquettes. Methods of sampling and preparation of samples for laboratory tests
GOST 11014-2001 Brown coals, stone coals, anthracite and oil shale. Accelerated Moisture Determination Methods
GOST 13455-91 Solid mineral fuel. Methods for the determination of carbon dioxide carbonates (ISO 925: 1997, MOD)
GOST 14198-78 Technical cyclohexane. Technical conditions
GOST 17070-87 Coals. Terms and Definitions
GOST 23083-78 Coal coke, pitch coke and thermoanthracite. Methods of sampling and preparation of test samples
GOST 25336-82 Laboratory glassware and equipment. Types, main parameters and dimensions
GOST 27313-95 Solid mineral fuel. Designation of quality indicators and formulas for recalculating the analysis results for various fuel conditions (ISO 1170: 1997, MOD)
GOST 27589-91 Coke. Method for determination of moisture in an analytical sample
Note - When using this standard, it is advisable to check the validity of reference standards in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet or according to the annual information index "National Standards", which was published as of January 1 of the current year, and by the editions of the monthly information index "National Standards" for the current year. If the referenced standard to which the undated reference is given has been replaced, it is recommended to use current version of this standard subject to all changes made to this version. If the referenced standard to which the dated reference is given is replaced, then it is recommended to use the version of that standard with the above year of approval (acceptance). If, after the approval of this standard, a change is made to the referenced standard to which the dated reference is given, affecting the provision to which the reference is made, then that provision is recommended to be applied without taking into account that change. If the reference standard is canceled without replacement, then the provision in which the reference to it is given is recommended to be applied in the part that does not affect this reference.
3 Terms and definitions
This standard uses terms and definitions for GOST 17070 .
Designation of quality indicators and indices to them - according to GOST 27313 .
4 Essence of methods
A weighed portion of an air-dry solid fuel sample is heated without access to air at a temperature of (900 ± 5) ° С for 7 min. The percentage yield of volatile substances is calculated from the weight loss of the sample weighed in, minus moisture.
When testing the fuel of the group of coal and coke (see Section 1), the following determination conditions were established: a sample in the form of a powder and heating in one furnace at (900 ± 5) ° С for 7 minutes.
When testing fuels of a group of brown coal (see section 1), the following alternative conditions for determination are established:
a) a sample in the form of a powder and successive heating in two ovens: at (400 ± 10) ° С for 7 min and at (900 ± 5) ° С for 7 min.
b) a briquetted portion of the sample and heating in one oven at (900 ± 5) ° С for 7 min.
If, when testing a sample under conditions a) and b), it is not possible to avoid the release of solid particles, then it is recommended to determine the yield of volatile substances under the following conditions: briquetting of a sample and sequential heating in two furnaces: at (400 ± 10) ° С for 7 minutes and at (900 ± 5) ° С for 7 min.
5 Reagents
5.1 Cyclohexane on GOST 14198.
5.2 Benzene GOST 5955 .
6 Apparatus
6.1 Muffle furnace
A muffle furnace with electric heating and a thermostat providing a constant temperature (900 ± 5) ° C in the working area of the furnace is used. For testing fuels belonging to the group of brown coals, a second muffle furnace of a similar design is additionally used, in the working area of which a constant temperature (400 ± 10) ° C is maintained.
Structurally, the muffle furnace can be with a closed back wall or have a branch pipe with a diameter of 25 mm and a length of 150 mm on the back wall (Figure 1).
Dimensions in millimeters
1 - heating system; 2 - constant temperature zone; 3 - control (not covered) thermocouple; 4 - muffle furnace chamber (width 200 mm); 5 - throttle valve; 6 - outlet tube; 7 - sheathed thermocouple
Picture 1 - Muffle furnace (example)
NOTE In muffle furnaces, the front door must be tightly closed. The branch pipe protrudes slightly above the furnace and must be fitted with a throttle valve to restrict the air flow through the muffle furnace.
The thermal power of the muffle furnace must be such that the initial temperature, equal to 900 ° C or 400 ° C, is restored after introducing a cold support with crucibles into the furnace in no more than 4 minutes. The temperature is measured with a thermocouple (6.2).
In a conventional muffle furnace (Figure 1), a series of determinations can be carried out simultaneously using a support for several crucibles.
In this case, the constant temperature zone must be at least 160x100 mm. For a single determination in one crucible on an individual support, the diameter of the constant temperature zone is 40 mm.
The oven temperature of 900 ° C should be maintained as precisely as possible. The permissible deviation of ± 5 ° С includes possible errors in temperature measurement and unevenness of its distribution.
6.2 Thermocouple
Thermoelectric converter for measuring temperatures up to 1000 ° С according to GOST R 50342 with a measuring device.
The temperature in the oven is measured using an unshielded thermocouple (control) made of wire no more than 1 mm thick. The length of the thermocouple must be sufficient so that the junction of the thermocouple inserted into the muffle furnace through the front or rear wall is midway between the bottom of the crucible, placed on the support, and the bottom of the furnace. If a rack with several crucibles is used, the temperature is checked under each crucible. It is allowed to check the temperature above the crucibles at the same level in the working area of the furnace.
If necessary, a sheathed thermocouple can be permanently located in the furnace, and its junction is placed as close as possible to the center of the constant temperature zone. The readings of the sheathed thermocouple must be checked at short intervals according to the readings of the uncovered thermocouple, which is introduced into the furnace for this purpose. A shrouded thermocouple is usually part of meter-regulator of temperature used in a muffle furnace.
NOTE The temperature / electromotive force ratio of the junction of the thermocouple used for the measurement high temperatures, gradually changes over time.
6.3 Crucible with lid
A cylindrical crucible with a well-fitting lid is made of fused silica glass. The weight of the crucible with the lid is from 10 to 14 g, the dimensions are shown in Figure 2. The lid must fit tightly to the crucible, the horizontal gap between the lid and the crucible should not exceed 0.5 mm. The matched lid is ground to the crucible, making the contacting surfaces smooth.
Dimensions in millimeters
Figure 2 - Quartz crucible with lid
NOTE For testing highly swollen coals, higher crucibles should be used. An increase in the height of the crucible to 45 mm does not affect the determination result if the rate of temperature recovery in the furnace is maintained.
It is allowed to use porcelain crucibles N 3 high form with lids on GOST 9147 ... The lids must be fitted and carefully ground in, and the lids are lapped to the porcelain crucibles by mechanical rotation until a groove is formed on the inner surface of the lid.
Crucibles with a fitted and ground-in lid should be marked identically, calcined at a temperature of (900 ± 5) ° С to constant weight and placed in a desiccator with a drying agent.
6.4 Crucible support
The support, on which the crucibles are placed in the muffle furnace, makes it possible to maintain the set heating rate.
The following stands are allowed:
a) for a single determination - a ring made of heat-resistant steel wire(Figure 3, a) with a ceramic disc 25 mm in diameter and 2 mm thick, placed on the inner projections of the supports;
b) to simultaneously carry out several determinations (two, four or six):
1) a frame made of heat-resistant steel wire with ceramic plates 2 mm thick, on which crucibles are placed (Figure 3, b);
2) a stand made of heat-resistant sheet steel, usually for six crucibles (if the size of the working area allows) (Figure 4).
Dimensions in millimeters
a) for a single definition
b) for several definitions
1 - three supports located in relation to each other at 120 °; 2 - ring; 3 - frame; 4 - ceramic plates
Figure 3 - Stands for crucibles
Dimensions in millimeters
Figure 4 - Stand for six crucibles
6.5 Balance
Laboratory balance on GOST R 53228 with a tolerance limit of ± 0.1 mg.
6.6 Press
Manual laboratory press with a matrix diameter of no more than 15 mm.
6.7 Desiccator
Use a desiccator on GOST 25336 with drying agent.
7 Sample preparation
7.1 A fuel sample for determining the volatile matter yield is an analytical sample taken and prepared in accordance with GOST 10742 or GOST 23083.
An analytical sample, crushed to a maximum particle size of 212 μm, must be in an air-dry state, for which it is laid out in a thin layer and kept in air at room temperature for the minimum time necessary to achieve equilibrium between the moisture content of the fuel and the laboratory atmosphere.
Before taking a portion, the sample is thoroughly mixed for at least 1 min, preferably mechanically.
Simultaneously with taking a sample for analysis, sample is taken to determine the content of analytical moisture in accordance with GOST R 52917 ,
GOST 11014 or GOST 27589 .
7.2 If the determination of the yield of volatile substances in coal and anthracite is carried out for the purpose of classification, their ash content should be no more than 10%. If the ash content of the sample exceeds 10%, the sample is enriched in organic or inorganic liquids in accordance with GOST 1186 and GOST 4790 .
Bituminous coals are enriched in liquids with a density of 1500 to 1600 kg / m, and anthracites - in liquids with a density of 1800 kg / m(zinc chloride). If, after enrichment of samples of coal and anthracite, their ash content exceeds 10%, the determination of the yield of volatile substances of the floating fraction is carried out at the actual ash content.
7.3 Briquetting a sample of brown coal
A weighed portion of an air-dry sample of brown coal, prepared according to 7.1, weighing (1 ± 0.1) g, is placed in the matrix of a laboratory press (6.6), covered with an insert on top, and then the punch is lowered by rotating the press screw or turning the handle and squeezing the coal until a briquette is formed ... The resulting briquette is taken out of the press and stored in a weighing bottle until testing.
8 Testing
8.1 Temperature control in muffle furnaces
In muffle furnaces, using permanently installed sheathed thermocouples, the operating temperatures are set (400 ± 10) ° C and (900 ± 5) ° C. They control the temperatures in the furnaces using unshielded thermocouples.
Stands filled with empty crucibles with lids are placed in the working areas of muffle furnaces. Check the temperature under each crucible at the same height using an uncovered thermocouple. The measured values of temperatures must be within the permissible deviations from the temperature of the working area. During all procedures during the test, the selected position of the support with crucibles in the working area of the furnace is adhered to.
It is allowed to place the junction of an uncovered thermocouple at the same height above the crucibles within the stable heating zone.
The oven temperature is checked prior to the start of the determination. With routine daily work, it is enough to carry out such a control on a monthly basis.
The check of the rate of temperature recovery in the oven is carried out in the same way.
8.2 Test preparation
The empty crucibles are closed with lids (6.3), placed on the support (6.4), filling all the slots, and placed in the zone of stable temperature of the muffle furnace heated to (900 ± 5) ° C. The crucibles are kept in a closed oven for 7 minutes.
Remove the support with crucibles from the oven, cool on a metal plate for 5 min without removing the lids, after which the crucibles are placed in a desiccator (6.7) and cooled to room temperature near the balance.
After cooling, empty lidded crucibles are weighed.
The procedure for calcining empty crucibles before each test use is optional. A sufficient condition for obtaining test results within the permissible discrepancies is the storage of pre-calcined crucibles in a desiccator with a drying agent and specification of the crucible mass immediately before placing a sample in it.
In a weighed crucible, place a weighed portion of the sample prepared in accordance with Section 7, weighing (1 ± 0.01) g. Close the crucible with a lid and weigh. All weighings are carried out with an error limit of ± 0.1 mg.
Spread the weighed portion in the form of powder over the bottom of the crucible in an even layer, lightly tapping the crucible on a clean hard surface.
When testing coke, remove the lid from the crucible, add 2-4 drops of cyclohexane (5.1) to the sample, and close the crucible with the lid again. It is allowed to use benzene (5.2) instead of cyclohexane.
NOTE Addition of cyclohexane or benzene prevents oxidation of coke.
8.3 Determination of the yield of volatile substances in coal and coke
The temperature is set in the muffle furnace (900 ± 5) ° C.
The crucibles with powder weights, closed with lids, are placed in the slots of the cold stand. If free slots remain on the stand, empty crucibles with lids are placed in them. The support with crucibles is transferred to a muffle furnace, the furnace door is closed and left for 7 min ± 5 s.
The temperature, which dropped when placing the crucibles in the furnace, must again reach (900 ± 5) ° С in no more than 4 minutes. Otherwise, the test is repeated.
8.4 Determination of volatile matter yield in brown coal (alternative methods)
8.4.1 Determination from powder in two ovens
In one muffle furnace, set the temperature to (400 ± 10) ° C, and in the other - (900 ± 5) ° C.
The crucibles with powder weights are closed with lids and placed in the slots of a cold stand. If free slots remain on the stand, empty crucibles with lids are placed in them. The support with crucibles is transferred to a muffle furnace heated to (400 ± 10) ° С, the furnace door is closed and left for 7 min ± 5 s. Remove the support and immediately place it in a muffle furnace heated to (900 ± 5) ° С, close the furnace door and leave for the next 7 min ± 5 s.
The temperature decreasing when the crucibles are installed in the furnace must again reach (400 ± 10) ° C and (900 ± 5) ° C in no more than 4 minutes. Otherwise, the test is repeated.
Remove the support with crucibles from the oven and cool on a metal plate for 5 min. After that, the crucibles, covered with lids, are transferred to a desiccator and cooled to room temperature near the balance.
The crucibles with a non-volatile residue are weighed.
After the test, non-volatile residues are removed from the crucibles. Open crucibles and lids are calcined in a muffle furnace at a temperature of (900 ± 5) ° С, cooled, freed from the ash residue and stored in a desiccator with a drying agent.
8.4.2 Determination from a briquetted sample in one oven
The temperature is set in the muffle furnace (900 ± 5) ° C.
Briquetted samples prepared according to 7.3 are placed in weighed crucibles. The crucibles are capped and weighed. Closed crucibles with briquettes are placed in the slots of a cold stand, leaving no empty slots. Further, the determination is carried out according to 8.3.
Notes (edit)
1 When testing some brown coals, lignites and products of their processing ejection of solid particles from the crucible cannot be avoided either when using the method of heating a sample in the form of a powder in two furnaces, nor when using the heating method briquetted sample in one oven... In such cases, the air-dry fuel sample is briquetted to 7.3 and then determining the volatiles yield by heating in two ovens.
2 The release of volatile substances is determined in parallel in two weighed portions of the sample. It is not recommended to test portions of the same sample on the same stand.
9 Characterization of non-volatile residue
___________________
* Title of section 9 in paper original is italicized. - Note from the manufacturer of the database.
Non-volatile residues obtained after determining the yield of volatile substances of coals are characterized depending on appearance and strength as follows:
- powdery;
- stuck together - with light pressure with a finger crumbles into powder;
- slightly sintered - with light pressure with a finger, it splits into separate pieces;
- sintered, not fused - force must be applied to split into separate pieces;
- fused, not swollen - flat cake with a silvery metallic sheen on the surface;
- fused, swollen - swollen non-volatile residue with a silvery metallic sheen of the surface with a height of less than 15 mm;
- fused, strongly swollen - swollen non-volatile residue with a silvery metallic surface over 15 mm in height.
10 Expression of results
The yield of volatile substances from the analytical sample of the test fuel, expressed as a percentage, is calculated by the formula:
where is the mass of an empty crucible with a lid, g;
Crucible weight with lid and sample weighed before testing, g;
- mass of crucible with lid and non-volatile residue after testing, g;
- mass fraction moisture in the analytical sample,%, determined by. (3)
If the mass fraction of carbon dioxide from carbonates in the fuel sample is more than 2%, the yield of volatiles corrected for carbon dioxide from carbonates , expressed as a percentage, is calculated by the formula
, (4)
where - mass fraction of carbon dioxide from carbonates in an analytical sample, determined by GOST 13455 , %;
- mass fraction of carbon dioxide from carbonates in the non-volatile residue, determined by GOST 13455 , %.
The test results are calculated to the second decimal place, and the final result, which is the arithmetic mean of the results of two parallel tests, is rounded to the first decimal place.
Recalculation of the test results for other states of fuel, other than air-dry, is carried out in accordance with GOST 27313.
11 Precision
The precision of the method is characterized by the repeatability and reproducibility of the results obtained.
11.1 Repeatability
The results of two parallel determinations carried out within a short period of time, but not simultaneously, in the same laboratory by the same performer using the same apparatus on representative weighed portions taken from the same analytical sample, should not differ from each other. more than the value of the repeatability limit given in table 1.
Table 1 - Limits of repeatability and reproducibility of the results of determining the yield of volatile substances
Coal name | Maximum permissible discrepancy between the results (calculated for the same mass fraction of moisture) |
|
Repeatability limit | Reproducibility limit |
|
Group of bituminous coals * with a volatile content of less than 10% | 0.3% absolute | 0.5% absolute |
Group of bituminous coals * with a volatile matter yield of 10% or more | 3% of the average | the larger of the two: 0.5% absolute or 4% of the mean |
0.2% absolute | 0.3% absolute |
|
Brown coal group * | 1.0% absolute | 3.0% absolute |
* See section 1. |
||
11.2 Reproducibility
The results, each of which is the arithmetic mean of the results of two parallel determinations carried out in two different laboratories on representative portions taken from the same sample after the last stage of its preparation, should not differ from each other by more than the value of the reproducibility limit, given in table 1.
If the discrepancy between the results of the two determinations is greater than the repeatability limit given in Table 1, a third determination is made. The test result is taken as the arithmetic mean of the results of two determinations, which are within the limits of permissible discrepancies.
If the result of the third determination is within the permissible discrepancy with respect to each of the two previous results, the arithmetic mean of the results of the three determinations is taken as the test result.
12 Test report
The test report must contain the following information:
- identification of the test sample;
- a reference to this International Standard;
- date of testing;
- test results with an indication of the state of the fuel they refer to;
- mass fraction of moisture and ash content of the air-dry sample, if the results are presented for the analytical state of the fuel;
- features observed during the test.
UDC 622.33: 543.813: 006.354 OKS 75.160.10 OKP 03 2000
Key words: solid mineral fuel, bituminous coal, brown coal, anthracite, oil shale, coke, determination method, volatile matter yield
_____________________________________________________________________
Electronic text of the document
prepared by Kodeks CJSC and verified by:
official publication
M .: Standartinform, 2014
FOSSIL COALS- solid combustible minerals; the product of the transformation of plants. Main components: carbonized organic matter, mineral impurities and moisture. They usually occur in the form of layers among sedimentary rocks. Subdivided into brown coals, bituminous coals and anthracites. Fossil coals are used mainly in the energy sector, for the production of metallurgical coke, and in the chemical industry. Main technological characteristics: ash content, moisture content, sulfur, volatile matter yield. World reserves are about 3700 billion tons.
Kuzbass is the main Russian base for solid fuels.
Technical analysis of coal
All types of solid fossil fuels combine two components: organic matter and a mineral component, which was previously considered as ballast, but is now increasingly considered a source of valuable mineral raw materials, in particular rare and trace elements. To assess the possibilities and modes of processing of fossil fuels, technical analysis is used, which makes it possible to determine the directions of their use as energy and chemical raw materials. Technical analysis refers to the definition of indicators provided for technical requirements on the quality of coal.
Technical analysis usually combines methods designed to determine ash content in coals and oil shale, moisture content, sulfur and phosphorus, volatile matter yield, heat of combustion, sintering capacity and some other quality and technological properties. A complete technical analysis is not always carried out; it is often sufficient to carry out an abbreviated technical analysis, consisting in determining the moisture content, ash content and the release of volatile substances.
Humidity
Due to the fact that water molecules can be bound to the surface of coal by forces of different nature (absorption on the surface and in pores, hydration of polar groups of macromolecules, inclusion in the composition of crystalline hydrates of the mineral part) at different ways When moisture is released from coal, different values of its dehydrated mass and, accordingly, different values of moisture are obtained.
The mass of coal with the moisture content with which it is shipped to the consumer is called the working mass of coal, and the moisture released from it when the sample is dried to constant mass at 105oC is called the total moisture of the working mass of coal.
The moisture content of a fossil fuel is characterized by its moisture content. This value is expressed by the ratio of the mass of moisture released at the dehydration temperature to the mass of the analyzed sample. Humidity is indicated by the letter W (Wasser).
Moisture in coal reduces the useful mass during transportation, a large amount of heat is spent on its evaporation when burning fuel, in addition, wet coal freezes in winter.
The total moisture content varies with the degree of coalification of the fossil in the next row.
Peat> Brown coals> Anthracites> Bituminous coals.
Ash content
Fossil coals contain a significant amount (2-50%) of minerals that form ash after combustion. The ash residue is formed after the calcination of coal in an open crucible in a muffle furnace at a temperature of 850 ± 25 ° C. Ash is 95-97% composed of oxides Al, Fe, Ca, Mg, Na, Si, K. The rest is compounds of P, Mn, Ba, Ti, Sb and rare and trace elements.
Ash content is designated by the letter Ad (Asche) and is expressed in wt%. The total moisture and ash content is called ballast. The content of the actual mineral substances is designated by the letter M. It is determined using physical and physicochemical methods (for example, microscopic, fluoroscopic, radioisotope).
Volatiles
Volatile substances are vapor and gaseous products released during the decomposition of organic matter of a solid fossil fuel when heated under standard conditions. The release of volatile substances is indicated by the symbol V (volativ), the yield for the analytical sample is Va, for dry matter Vd, dry and ash-free Vdaf. This characteristic is important for assessing the thermal stability of the structures that make up the organic mass of coal. The release of volatile substances during calcination served as the basis for one of the classifications of coals by grade.
| Brand | Designation Group brands |
Volatile release |
Thickness of plastic |
|
|---|---|---|---|---|
| Long flame | D | more than 37 | ||
| Gas | G | G6 G7 | more than 37 | 17 - 25 |
| Gas fat | GZH | - | more than 31 -37 | 17 - 25 |
| Fatty | F | 1Ж26 2Ж26 | more than 33 | 26 and more |
| Coke bold | QL | KZh14 KZh6 |
25 - 31 | 6 - 25 |
| Coke | TO | K13 K10 | 17 - 25 | 13 - 25 |
| Coke second | K2 | - | 17 - 25 | |
| Lean sintered | OS | - | less than 17 | 6 - 9 |
| Weakly baking | SS | 1CC 2CC | 25 - 35 | |
| Skinny | T | - | less than 17 | |
| Anthracite | A | - | less than 10 | |
Heat of combustion
Calorific value is the main energy indicator of coal. It is determined experimentally by burning a sample of coal in a calorimetric bomb or by calculation using elemental analysis data.
Distinguish the highest heat of combustion of coal Qs as the amount of heat released during the complete combustion of a unit mass of coal in a calorimetric bomb in an oxygen atmosphere and the lowest specific heat of combustion Qi as the highest heat of combustion minus the heat of vaporization of water released and formed from coal during combustion. The highest heat of combustion is often determined for the ashless state of coal Q s af, and the lowest for the working state Qir. DI. Mendeleev proposed a formula for calculating the highest calorific value from elemental analysis data (kcal / kg):
Qsaf = 81 ° С + 300Н-26 (О-S), where С, Н, О, S - mass fraction of elements in TGI substance,%.
Higher calorific value of basic solid fuels:
Sintering capacity
One of the most important, if not the most important, direction of using coal is its processing into metallurgical coke - a solid product of high-temperature (> 900C) decomposition of coal without air access, which has certain properties. Not all coals are capable of sintering, i.e. when heated without access to air, pass into a plastic state with the subsequent formation of a bound non-volatile residue. If this sintered residue meets the requirements for metallurgical coke, then one speaks of coking coal. Thus, coking is sintering, but the first concept is narrower. Coals of grades G, Zh, K, OS are sintered, but metallurgical coke can be obtained only from coals of grade K or from a mixture of coals, which in properties is close to them.
Elemental analysis of TGI
As already mentioned, the organic matter of all types of TGI consists of C, H, O, S, and N. Their total amount exceeds 99 wt%, calculated on the organic matter of any coal and peat.
Carbon and hydrogen are determined by the yield of CO2 and H2O during combustion of a sample of coal in a stream of oxygen. These oxides are captured in absorbing apparatus filled with KOH and H2SO 4 solutions, respectively. The latter are weighed before and after combustion of the sample, and the C and H content in the sample is calculated from the mass difference, usually in wt%. It should be noted that in this case the results can be distorted due to the absorption of water and carbon dioxide, which are of inorganic origin, and formed due to the thermal decomposition of the mineral components of coal.
In general, sulfur is more common in coals. Its content ranges from fractions of a percent to 10-12%. Distinguish between sulfate (SSO4), pyrite (Sp) and organic sulfur (So), their total content is called total sulfur (St). The sulfur content, determined from elemental analysis data, is an important characteristic that determines the special requirements for the processing and use of raw materials characterized by its high concentration. Evolved volatile sulphurous products such as H2S and SO2 are extremely hazardous if released into environment, and when designing production facilities, one should take into account their high corrosive activity.
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