Purpose of the analyser
The WILPO L 241 Analyser is designed for rapid determination of basic coal quality parameters (ash [Ar], moisture [Wtr] and sulphur [Str] content) and for instant determination of calorific value of coal in technical samples of coal (in as-is condition). The design of the unit and original, patented measurement methods enable the analyser to be used in laboratories in mines, power plants, heat generating plants, coke plants, and also in on-site testing laboratories, storage yards, etc.
Our most recent development among analysers, the WILPO L 241, can measure four basic coal quality parameters with higher accuracy than WILPO L 132 / L 142 analysers and eliminate or minimize the impact of chemical composition variability of coal on measurement results.
General design and operating principle
The WILPO L 241 Analyser is designed as a single-module unit, which enables its easy use in any place.
The measurement vessel with the coal (or e.g. biomass) sample, upon placing it on the loader, is positioned precisely between probes in the measurement paths. During measurement the vessel is slowly rotated so that the entire sample is shifted many times between the probes. The sample is exposed to gamma rays, X-rays and microwaves and the measurement signals (electric pulses) from respective measurement paths are relayed to the control and measurement module, where they are counted and processed. Results of every measurement, along with additional information entered from the keyboard, such as sample number, coal buyer, etc., appear on the display and are automatically saved in computer memory.
The database that is created enables printing out of results as required by the user, e.g. results from a period of one month for coal sent to a selected buyer or provided by a selected supplier, results for samples analysed during one day with daily mean values of coal quality parameters, etc. The latest probes, electronic large-scale integration components and a fast computer system with printer provide reliable and accurate operation, as well as comfort of use.
Fig. 1 shows a simplified diagram of the analyser, where:
- 1 and 5 – transmitting and receiving microwave antennas
- 2 – microwave radiation beam
- 3 – coal sample
- 4 – rotating measurement vessel
- 6 – container with radiation source and target positioning system
- 7 – X-ray and gamma ray beam
- 8 – ionizing radiation detector
- 9 – control and measurement module
Analyser operation
Sample preparation:
A ca. 1 kg sample, in as-is condition, is poured into a crusher (preferably a roll crusher, e.g. LAB-08-240), where it is comminuted. Afterwards the coal sample comminuted to grain size 0 to 6 mm is poured, without weighing and drying, to the measurement vessel and the top surface of coal is levelled with the roller, which is part of instrument equipment (the measurement method applied eliminates the effect of sample packing on measurement results). The sample is levelled with the roller in order to ensure complete filling of the vessel and thereby to ensure proper measurement.
Measurement:
The carrying out of measurement is simple and consists of placing the vessel with the sample on the analyser loader, pushing the loader into the analyser and pressing the start button on the keyboard. Functions of important keys are shown on the display. Measurement takes 200 seconds, after which measurement results are displayed and automatically entered into the database. Details of analyser operation and database handling are given in the Analyser Operating Manual.
Operating safety
The Analyser is an isotopic instrument with a low-energy gamma radiation source. The design of the instrument ensures complete safety of its operation. Its manufacture has been approved by the State Atomic Energy Agency in Warsaw (permit no. D-14478 of 11.09.2002, annex no. 1 of 2.02.2006).
Specyfications
|
Coal size |
ca. 0-6 mm |
|
Sample weight |
0.4-0.7 kg, depending on coal type, ash content, degree of packing |
|
Sample preparation time |
ca. 100 sec. |
|
Measurement time |
200 sec. |
|
Ash and sulphur determination method |
gamma and X-ray absorption |
|
Radiation source |
Am-241 isotope, activity ca. 4 GBq, in a protective container of special design |
|
Moisture determination method |
microwave absorption |
|
Microwave radiation characteristics |
– frequency: ~9.35 GHz |
|
Dimensions: |
1000 x 800 x 1550 mm |
|
Weight: |
ca. 95 kg |
|
Power supply: |
230V (±10%), 50 Hz |
Measurement accuracy defined as average, absolute values, dependent on coal type and measuring range
|
VALUE MEASURED |
COAL TYPE AND RANGE OF VARIATION OF MEASURED VALUE |
MEASUREMENT ERROR σ |
|
Ash content Ar |
Large size coal and some washed coal grades, ash content 2 – 10% |
0.5 – 0.7% |
|
Raw fines – ash content 15 – 35% |
1.0 – 1.5% |
|
|
Coal smut and waste – ash content 25 – 50% |
1.0 – 2.0% |
|
|
Waste and rock – ash content 50 – 85% |
2.0 – 3.5% |
|
|
Moisture content Wtr |
Moisture content range 2 – 10% |
0.5 – 0.7% |
|
Moisture content range 10 – 25% |
0.7 – 1.0% |
|
|
Sulphur content Str |
Sulphur content 0,2 – 1,0% |
0.05 – 0.15 |
|
Sulphur content 0,5 – 1,5% |
0.1 – 0.2 |
|
|
Sulphur content 1,0 – 3,0% |
0.1 – 0.3 |
|
|
Calorific value Qir |
Complete range |
100 – 500 kJ/kg |
|
Combustibles content |
Complete range |
ca. 0.5% combustibles |
