The sulfur in coal is one of the important evaluation index of coal, is the main source of acid rain formation in combustion process. 3 methods for the determination of total sulfur in coal, namely, the method of the weight of the high temperature combustion, and the method of high temperature combustion, and the Coulomb method. The first two methods are cumbersome and difficult to operate. The use of Coulomb method for the determination of total sulfur in coal has been widely used in various industries. At the beginning of the establishment of the Shiling Industrial Company laboratory, purchased the 6Y.SJCLY-300Y SJCLY- 2 test instrument. The instrument has a fast detection speed, short cycle, simple operation, and the accuracy and precision of the instrument can meet the need of coal inspection.

Working principle

Coal in high temperature furnace 1150, the catalyst (WO3) the effect of air flow on combustion, decomposition. All forms of sulfur in coal were oxidized and decomposed into sulfur dioxide and a small amount of sulfur trioxide (referred to as sulfur compounds), and by the air flow to the electrolytic cell, combine it with water to generate sulfurous acid and a small amount of sulfate, sulfite oxidation titration with iodine and bromine generated by the electrolysis of potassium iodide potassium bromide solution. The content of total sulfur in coal is calculated according to the amount of electricity consumed by electrolysis. The Coulomb gauge is designed according to the principle of dynamic Coulomb analysis to achieve the dynamic tracking titration, which can obtain accurate measurement results.

Two. Several reasons affecting the accuracy of total sulfur determination

1 air flow factor. According to the analysis of the reasons, when the air flow rate is lower than 1000ml/min, some coal samples may not be complete, and because the gas flow rate is small, the iodine can not be quickly spread, and the results are low. When the air flow is too large, some SO2 may be too late.

2 color factors of silica gel in silica gel drying tube. When the 2/3 in the dry tube is pink, the detected data are in the range of the specified requirements. And when the silica gel 2/3 in the silica gel into a pink, the detected data are significantly lower.

3 factors affecting the stirring speed. When the stirring speed is 500r/min, the detected data are in the range of uncertainty in the specified requirements. When the stirring speed is less than 500r/min, the detected data are obviously lower. Analysis of its causes, stirring speed is too slow, the electrolysis of iodine and bromine can not get rapid expansion, will make the end of failure, making the determination of the low. Stirring speed too fast can easily lead to mixing son out of control, resulting in civil strife electrolysis pool jumped and bending electrode sheet, or even damage the electrolytic cell and affect the normal determination.

4 air tightness of the whole system. When checking the air tightness of the whole system is good, the detected data are in the range of uncertainty in the specified requirements. When the air leakage of the whole system, the detected data are significantly lower.

5 the influence factors of the pollution on the determination results of electrode in the electrolytic cell. When the electrode piece in the electrolytic cell is not polluted, the detected data are in the range of uncertainty of the specified requirements. When the electrode in the electrolytic cell is polluted, the detected data are obviously lower. Analysis of the original cause, the electrode in the electrolytic cell by pollution, the electrolyte was not in time, will cause the detection results are low.

6 the influence of different pH value of electrolyte on the results. When the pH value of the electrolyte is not less than 1, the detected data are in the range of uncertainty in the specified requirements. When the pH value of the electrolyte is less than 1, the detected data is significantly lower. Analysis of the reasons, when the electrolyte PH is less than 1, it shows that with the increase of the number of the electrolyte, when the electrolyte is strong, will lead to the low value of the determination.

7 factors affecting the results of the sintering process. When there is no black precipitate in the sintering process, the detected data are in the range of uncertainty of the specified requirements. When the sintering in the electrolytic tank is obviously black, the detected data are obviously lower. Analysis of the reasons, the sintering of the electrolytic tank and glass pipe with black precipitation, can plug the gas path, reduce air flow, will cause the determination results is low.

The effects of 8 factors covered tungsten trioxide. When in the coal sample uniform coverage of a thin layer of tungsten trioxide and obtained test data were in accordance with the requirements of uncertain degree range. When a thin layer of three tungsten oxide is uniformly covered by a thin layer, the detected data are obviously lower. Analysis of its causes, WO3 as a promotion and catalytic decomposition of sulfate sulfur in coal, can make the completely decomposed at lower temperature (1100 1200 DEG C) of sulfate sulfur in coal.

9 porcelain boat whether to enter the constant temperature area of the impact factors of the results. When equipped with coal samples of porcelain boat enters a combustion furnace temperature zone and obtained test data were in accordance with the requirements of the uncertain degree range. When the porcelain boat with coal sample was not entered into the constant temperature zone in the furnace, the detected data were significantly lower. Analysis of its causes, with the coal sample of the porcelain boat in the constant temperature area, will make the coal sample combustion is not complete, the result is low.

10 the influence factors of the calibration of the coulomb sulfur measuring instrument. The calibration coefficient of the instrument calibration can not be detected in the range of the total sulfur test results. The reason of the analyzer is the calibration coefficient of the instrument calibration.

Conclusion