LAB TEST

The sample received is homogenized. By dividing the samples, the laboratory technicians produce the samples sufficient for the appropriate number of test, thus preserving the representativeness of the sample received by the laboratory.

The moisture content is determined by the drying oven method. The prepared samples are weighed on certified scales in uniquely identified stainless steel vessels and then dried at 105°C in a drying oven with forced air circulation until they reach constant weight.

By testing parallel (double) samples, we minimize the differences due to the variance in the quality of the biomass – the average value of the results of which gives the value of the moisture content by weight in accordance with the standard.

Representative samples dried to constant weight are shredded to a maximum grain size of 1 mm with a modern rotary cutter equipped with a screen and cyclone. The shredded sample is placed in an airtight plastic box with a unique identifier.

The shredded sample is further divided into smaller test portions. A minimum of 1g sample is used for determining the ash content, which is weighed on certified, high-resolution analytical balances. These tests are performed also on parallel samples. The weighed samples are put into porcelain vessels with unique identifiers and placed in the annealing furnace for the annealing cycles specified in the standards and spend approximately 5 hours there, after which the samples are cooled back. After another weight measurement the ash content can be calculated from the obtained data.

In parallel with the ash content, also the test portion of the calorific value test is measured from the shredded sample, which, after compaction, is placed in a so-called bomb. The test is performed by a fully automated state-of-the-art high precision calorimeter. It fills the bomb with 30 bar of high purity oxygen and submerges it into an enclosed body of water. It ignites the sample in the bomb, which, in the midst of intense combustion, dissipates heat to the surrounding, continuously monitored water with set temperature and known volume inside the machine. From this temperature rise the heat of combustion and the calorific value for the different conditions of the material (wet or dry) can be calculated.

Since the fully dried biofuels and SRF are able to absorb moisture from the air in a short time, thus the hygroscopic moisture content of the sample is determined parallel with the other tests and the test results are corrected with it.

The values to be measured according to the standard are recorded on the measurement sheet. In the digital data recording system, the staff members retrieve the data sheet based on the unique identifier of the sample, which data sheet was created when the sample arrived and the sampling data were recorded. The measured values, corrections, and all relevant information about the tests and samples are then recorded from the measurement sheet. From the results, an automatic system performs the calculations and prepares a report, which after checking and printing, is filed.

The tested samples are stored by the laboratory for 14 days from the date of arrival at the laboratory and are then discarded.