Method for measuring the calorific value of coal

First, the method summary

A certain amount of the analytical sample is burned in an oxygen bomb calorimeter in an oxygen bomb filled with excess oxygen. The heat capacity of the oxygen bomb calorimeter is determined by burning a certain amount of the reference amount of hot benzoic acid under similar conditions. According to the temperature rise generated by the calorimetric system before and after the test, and the additional heat such as ignition heat is corrected, the heat capacity can be obtained. The cartridge of the sample generates heat.

The high calorific value is obtained after the heat of the nitric acid is formed and the heat of the sulfuric acid is corrected from the calorific value of the cartridge.

The calorific heat of the moisture in the coal is corrected to obtain the positional calorific value.

Second, the measurement step (adiabatic calorimeter method)

(1) accurately weighed metal pan burning quality.

(2) Take a piece of ignition wire of known mass, connect the two ends to the two electrodes separately, and ensure that the contact is good. Place the combustion vessel on the bracket and adjust the drooping ignition wire to contact or keep a small distance in the coal sample. .

(3) Add 10 ml of distilled water to the oxygen bomb, carefully tighten the oxygen bomb cover, taking care to avoid the position of the combustion vessel and the ignition wire being changed by vibration.

(4) Add enough distilled water to the inner cylinder so that the top surface of the oxygen bomb is submerged 10-20mm below the water surface, and adjust the water temperature of the inner cylinder to be close to room temperature, and the difference should not exceed 5 °C.

(5) Place the mounted inner cylinder on the insulating bracket of the outer cylinder, carefully place the oxygen bomb into the inner cylinder, and check the airtightness of the cylinder.

(6) After installing the inner cylinder, the oxygen bomb, the agitator and the thermometer, start the agitator and the outer cylinder to circulate the water water paddle, and open the outer cylinder cooling hydration heater to automatically control, about 3-5 times per minute. If the thyristor control is used, the heater has a micro-thermal current indication.

(7) After adjusting the cooling water, start reading the temperature and read it to 0.001 °C with a magnifying glass. Before each reading, start the oscillator for 3-5 s.

(8) After 6-7 minutes of ignition, the inner cylinder temperature is read at intervals of 7 minutes until the difference of three consecutive readings does not exceed 0.001 °C, and the highest reading is taken as the end temperature.

(9) Turn off the agitator and heater and take out the oxygen bomb.

(10) When igniting with a wire, find the unburned ignition wire, measure its length, and calculate the actual consumption.

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