Research Of Accelerating Rate Calorimetry Based On Differential Power Compensation Method

As an important scientific instrument for thermal safety assessment of reactions,accelerating rate calorimeter simulates the thermal runaway process of samples in adiabatic state and analyses the experimental data to obtain important indicators to characterize the thermal hazards of chemical processes.However,the thermal inertia of sample container is a common problem in accelerating rate calorimeter,that is,the adiabatic performance of the reaction system decreases due to the heat dissipation of the sample to the sample container during the reaction stage,which lead to the adiabatic temperature rise decreases and the maximum reaction rate reaches time increases.Therefore,an accelerating rate calorimetry based on differential power compensation can effectively compensate the thermal inertia problem by optimizing the instrument structure and temperature control method.In order to study this method,after analyzing the principle of differential power compensation,the heat transfer model of reaction system is established according to energy equation and nth-order reaction theory.The advantages of differential power compensation principle are verified by comparing the simulation results of different principles,and then the power compensation scheme of reaction stage is determined.Afterward,the power compensation structure is put forward with the heat transfer model improved,which provide a basis for subsequent analysis work.Thereafter,the overall design scheme of the system is determined according to the principle requirement,and the furnace body,the uniform heat block and the sample container are designed in structures and materials.Meanwhile,the hardware and software of the measurement and control system of the experimental platform are built.The PID control algorithm combined with feedforward compensation and power distribution is determined for the non-linear large hysteresis furnace body,and the control method with integral separation and variable proportional gain is designed for the uniform heat block.Finally,the detection and tracking algorithm of the response is designed?Because the principle of differential power compensation has a highly requirement for the consistency of temperature measurement and control in two channels,a set of system consistency calibration methods for two-sided uniform block thermocouples,furnace thermocouples and uniform block heating rods are designed to improve the symmetry of temperature field in the dual-channel system.Last,the advantages and stability of the principle of differential power compensation are verified by comparing the experimental results with those without power compensation measures and repeatability experiments.