Preparation before calibration

Before calibrating the coal plant calorimeter, make sure that the instrument is in a stable state, placed in a horizontal, dry and non-strong electromagnetic interference environment. Prepare standard benzoic acid, its calorific value is accurately known, and the purity meets the requirements, which is the key substance for calibration. At the same time, check the oxygen bomb of the calorimeter to ensure that it is well sealed, there is no air leakage, the electrode contact is normal, and the ignition wire is firmly connected.

II. Specific steps for calibration

1. Weigh the standard sample: Use a high-precision balance to accurately weigh a certain mass (usually about 1g) of standard benzoic acid, record its mass value, accurate to four decimal places, and the accuracy of the quality has a significant impact on the calibration results.

2. Sample loading and installation of oxygen bomb: put the weighed benzoic acid into the crucible, place the crucible on the electrode holder in the oxygen bomb, connect the ignition wire to ensure that the ignition wire is in good contact with the benzoic acid. Then install the oxygen bomb, fill it with an appropriate amount of oxygen, and control the pressure within the specified range, generally 2.8-3.0MPa. The oxygenation time is not less than 15 seconds to ensure sufficient oxygen.

3. Instrument parameter settings: Turn on the calorimeter power supply, enter the calibration procedure, and set relevant parameters, such as calibration mode, standard calorific value, etc., according to the instrument manual to ensure that the parameters match the standard benzoic acid information.

4. Calibration test: put the oxygen bomb installed with the sample into the calorimeter, close the outer cover of the instrument, and start the calibration test procedure. The instrument automatically completes the ignition, measurement, calculation and other processes. After the test is completed, record the measured calorific value displayed by the instrument.

III. Calculation and verification of calibration results

Calculate the calibration coefficient according to the formula, the calibration coefficient = the calorific value of standard benzoic acid/the measured calorific value. Repeat the calibration operation many times, usually at least 3-5 times, and take the average value of the calibration coefficient as the final calibration coefficient. If the deviation of each calibration coefficient is within the allowable range, usually no more than 0.2%, the calibration result is valid. If the deviation is too large, check the operation process and re-calibrate.

IV. Maintenance after calibration

After the calibration is completed, clean the oxygen bomb in time, wipe the crucible, and properly store the standard benzoic acid. Regularly maintain and check the calorimeter to ensure the stable performance of the instrument and provide a reliable guarantee for subsequent coal quality testing. Through standardized calibration operations, the coal plant calorimeter can accurately measure and help control coal quality.