Coal Spontaneous Combustion Tendency Of Oxidation Kinetics Testing System And Automatic Control

Coal spontaneous combustion is one of the important disasters in China coal industry. It will not only cause a serious waste of energy, but also evoke coal dust and gas explosion which brought bad influence to the safety production of the coal industry. Therefore, the relevant departments of the coal industry have always attached great importance to the prevention and control of coal spontaneous combustion. The identification of the propensity to spontaneous combustion is the basis for determination of coal spontaneous combustion prevention. Its importance is self-evident. But, our research on coal spontaneous combustion which compared with foreign advanced level is still relatively weak. Therefore, The paper will study on the key technical problems of testing system for identifying the propensity of coal spontaneous combustion.Firstly, the paper makes a deep analysis of the distribution characteristics of the gas flow in coal samples of different physical dimension of the reaction tank, and study the coal sample reaction tank oxygen consumption characteristics by using Fluent simulation technology. Through the above research, we determine the cylinder coal sample tank of45mm diameter for the best physical size. In addition, also analyze the influence of different location of coal sample reaction tank in the test furnace for testing the distribution of furnace temperature field. Ultimately, we determine the relative optimal placement.In the development process of oxidation kinetics testing system of coal spontaneous combustion, high resolution temperature measurement is the key point of the whole system. Because it is a scientific analysis instrument, the measuring accuracy is very high, And the temperature measurement is the basis of accurate automatic control of follow-up. Through the analysis of the temperature measurement of the theoretical calculation and the error, we design the test system of temperature resolution of0.0067℃in the range of0-400℃。Some indicators meet the foreign progressive Corp(Shimadzu Corporation) performance of similar instruments. Automatic control of the whole testing system is another key point and the difficulty. Speaking of the entire test system, many control problems involved. In the paper, the choice of test furnace temperature control as the object of study. Firstly, we use the engineering tuning method and equation method respectively to the control system mathematical modeling analysis. Through the comparative study, we choose the latter method. But the control objects of the paper, its control range span, control of high precision. It is very difficult to establish an accurate mathematical model of the control object. We use the PID algorithm and the optimization of control parameters P,I,D etc to design controller. Through the theoretical calculation and simulation, the relevant control indicators meet the needs. Based on theoretical verification, we have achieved the PID controller and its application in test system. During the experiment, especially at high temperature range(250-400℃), we found that the control performance of the control algorithm is decreased a lot, it has been unable to meet the demand of the system in the control respect. In order to overcome these defects, we need to study and optimize the new control algorithm. Through the comparative study, we chose the fuzzy control algorithm which has a significant advantage that can achieve better control effect in the circumstances of indistinct mathematical model.The oxidation kinetics method of coal spontaneous combustion tendency is a relatively new method. But the shortest coal spontaneous combustion period and the parameters used more widely. Through the study of the relation between the test data and the shortest coal spontaneous combustion period, the paper can more accurately estimate the shortest coal spontaneous combustion period, and integrate it into the test software which developed by author. It is very good to expand the application field of the test system and shorten the time of test period and the complexity of the shortest coal spontaneous combustion.