DIN 51732 Testing of Solid Mineral Fuels - Determination of Total Carbon, Hydrogen and Nitrogen - Instrumental Methods

The standard “DIN 51732 Testing of solid mineral fuels - Determination of total carbon, hydrogen and nitrogen - Instrumental methods”, published by the German Institute for Standardization (DIN), is applicable to the instrumental determination of the total carbon, hydrogen and nitrogen content of coal, brown coal and lignite, as well as coke. This standard is also applicable to other solid or liquid substances.

The DIN 51732 standard includes instrumental methods used to determine the total carbon, hydrogen, and nitrogen content in solid mineral fuels. This standard applies to:

Hard coals
Brown coals and lignite coals
coke

This standard describes modern instrumental techniques (primarily dry combustion/elemental analyzers) for measuring total carbon, hydrogen, and nitrogen content. These values are required for:

Fuel characterization and quality control.
Calorific value calculation
Emission forecasts (especially nitrogen oxides)
Classification and trade of solid fuels.
Research and certification (e.g., in biochar production under the European biochar certification)

This method includes the total carbon (organic + any carbonate carbon present in the sample).

This standard does not cover the determination of sulfur or chlorine. These are addressed in separate norms (e.g., DIN EN 15408 or DIN 51724 standards for sulfur in fuels).

This method generally follows these steps (the most common procedure):

A small sample (typically 50–200 mg, ground and dried) is weighed precisely.
The sample is incinerated at a high temperature (typically 900-1200 degrees Celsius) in a pure oxygen environment inside an elemental analyzer.
The combustion products are:
Carbon dioxide from carbon
Hydrogen from water
Nitrogen or nitrogen oxides from nitrogen
The gases are separated (via gas chromatography or selective traps) and quantified using thermal conductivity detectors for nitrogen and infrared (IR) detectors for carbon dioxide and water.
Results are calculated as a percentage of mass on a dry basis (or as taken depending on requirements).

The DIN 51732 standard defines the following:

Device requirements
Calibration procedures (using coal standards or certified reference materials)
Accuracy and precision criteria
Sample preparation rules
Reporting format

This standard is essentially closely aligned with the “ISO 29541 Solid mineral fuels - Determination of total carbon, hydrogen and nitrogen - Instrumental method” standard, which uses the same principle.

The DIN 51732 standard is frequently listed as the reference method for CHN analysis of coals, cokes, and increasingly biochars and solid recovered fuels. Many biochar certification programs explicitly permit or recommend this method (often in conjunction with the ISO 29541 standard).

In short, total carbon, hydrogen, and nitrogen determination is a fundamental analytical procedure used to characterize organic matter, fuels, chemicals, polymers, soils, and biological samples. This analysis is commonly known as CHN elemental analysis.

CHN analysis is used for the following purposes:

To determine the elemental composition of organic substances.
Verifying chemical formulas
Calculating empirical formulas
Evaluating fuel quality (coal, coke, biomass)
Supporting environmental and agricultural testing.

In fuel analysis, total carbon and hydrogen are used to estimate calorific value, while nitrogen is important for estimating NOx emissions during combustion.

The DIN 51732 standard is used specifically in the elemental analysis of fuels such as coal, coke, biomass, and similar materials. This standard aims to reliably measure the percentages of carbon, hydrogen, and nitrogen necessary to determine the following characteristics of the fuel:

Combustion efficiency
Calcium value calculations
Emission estimates (such as carbon dioxide, nitrogen oxides)
Chemical characterization

The DIN 51732 standard is used particularly in the following areas:

Fuel quality control in thermal power plants.
Coal and coke analysis
Characterization of biomass and alternative fuels.
Laboratory research
Waste fuel analyses

The main reasons why this standard is considered important are as follows:

It ensures the accuracy of combustion calculations.
It provides essential data for emission control.
Used in calorific value calculations.
It serves as a reference point in international comparisons.

The DIN 51732 standard is generally evaluated using the following analyses:

Determination of moisture
Ash determination
Sulfur analysis
Calculations of lower and upper calorific values.

All of these analyses together are called elemental analysis.

In conclusion, the DIN 51732 standard is a reliable elemental analysis standard developed to determine the chemical composition of fuels in detail. It plays a critical role in energy production, environmental assessment, and fuel performance analysis. This standard provides a reliable, repeatable, and widely accepted instrumental procedure for the rapid and accurate determination of the three essential organic elements in solid fossil fuels. This standard has formed the basis of coal and coke analysis in many countries for quality assurance, contract specification, and environmental compliance.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "DIN 51732 Testing of solid mineral fuels - Determination of total carbon, hydrogen and nitrogen - Instrumental methods" standard.