Zhongke Sanbo ZDHW-A8 high-precision automatic automatic calorimeter:

First of all, the quality of the components on the device itself has a direct impact on the resulting data. The more sophisticated the performance of the instrument, the higher the automation program can minimize human-induced error. Specifically, the oxygen bomb is not affected by the high temperature and corrosive products that occur in the combustion process and generates a thermal effect; the propeller stirrer should be stable. Stirring efficiency should be such that the time from the ignition to the end of the heat capacity calibration does not exceed 10 min, and at the same time avoid excessive heat of stirring; the accurate measurement of the thermometer is of special significance; the combustion flank can ensure that the sample burns completely and itself It is not subject to corrosion and thermal effects; the outer barrel temperature is affected by the number of tests, and the uncertainty of the heat capacity is increased compared to an instrument whose barrel temperature is not affected by the number of tests.

Second, in the actual operation, attention should be paid to every detail to avoid system error and accidental error caused by human error.

1. Ambient temperature balance. The calorimeter calculates the calorific value of a substance by reading the temperature rise, and its temperature accuracy is one ten-thousandth degree. Therefore, the balance between the instrument and the environment before measurement is important. First of all, the laboratory should be set up in a separate room. Other test items must not be conducted in the same room at the same time. There should not be strong heat sources and fans. The lab is best facing north to avoid sunlight. Secondly, keep the ambient temperature stable and constant, and there should be no strong air convection in the room. Avoid opening doors and windows during the test. If conditions permit, air conditioning should be started before testing to balance the temperature of the equipment and the environment. The room temperature should be kept as constant as possible, usually room temperature does not exceed 15 °C ~ 35 °C range is appropriate. When the ambient temperature is stable at a certain point, and the barrel temperature is consistent with the ambient temperature, the heat capacity of the calorimeter's thermal system is determined, and test results with good reproducibility and accuracy can be obtained.

2. Sample preparation should ensure the dryness and fineness of the analytical sample. Wet sample and coal sample are too thick and can lead to incomplete combustion of the sample and low test results.

3. For samples with poor coal quality, too low volatility, easy to spill during combustion, and high moisture content in the sample, a suitable proportion of standard coal should be mixed or coated with a known quality and calorific value. Then squeeze it with your hand and place it in the combustion bowl. For samples with incomplete combustion, an asbestos mat may be placed on the bottom of the combustion pan, or as a liner with asbestos. The quartz burner does not require any gaskets. If the liner is still incompletely burned, the oxygenation pressure can be increased to 3.0MPa to 3.2MPa.

4. When the oxygen bomb is oxygenated, sufficient oxygen pressure should be ensured to fully burn the specimen. First, check whether the oxygen pressure gauge is intact, sensitive, and the pressure indicated is correct. During oxygenation, the pressure must be slowly increased. The oxygenation time should be maintained for 0.5 min to 1 min after reaching the specified pressure. When the oxygen pressure in the cylinder falls below 5.0 MPa, the oxygenation time should be extended. The oxygenation pressure must not be too low or too high.

5. The oxygen bomb can be completely airtight during the experiment. One is to ensure safety, and the other is to ensure the accuracy of the data. If a bubble is found in the water, the oxygen bomb leaks; the oxygen bomb of the new oxygen bomb and the newly replaced part should be subjected to a hydrostatic test of 15.0 MPa. Can only be used after the problem. In addition, attention should always be paid to observing structures related to the oxygen bomb strength, such as the thread of the cup body and the connecting ring, the connection between the oxygen valve and the electrode and the cover, etc. If significant wear or looseness is found, repairs should be made and water pressure applied. After the test. In addition, hydrostatic tests should be conducted on oxygen bombs on a regular basis. After each hydrostatic test, the use of oxygen bombs must not exceed one year.

6. For coal samples with low volatility and relatively wet conditions, incomplete combustion often results in large deviations in the results. Therefore, each time the sample is tested, it must be checked in the combustion vessel and in the oxygen bomb. No unburnt coal samples, if any, should be re-measured after treatment.

7. The instrument shall be periodically sent to the metrology authority for verification and correction of the calibration certificate to make necessary corrections.