Failure evolution and disaster prediction of rock under uniaxial compression based on non-extensive statistical analysis of electric potential

Rock failure can cause serious geological disasters,and the non-extensive statistical features of electric potential(EP)are expected to provide valuable information for disaster prediction.In this paper,the uniaxial compression experiments with EP monitoring were carried out on fine sandstone,marble and granite samples under four displacement rates.The Tsallis entropy q value of EPs is used to analyze the selforganization evolution of rock failure.Then the influence of displacement rate and rock type on q value are explored by mineral structure and fracture modes.A self-organized critical prediction method with q value is proposed.The results show that the probability density function(PDF)of EPs follows the q-Gaussian distribution.The displacement rate is positively correlated with q value.With the displacement rate increasing,the fracture mode changes,the damage degree intensifies,and the microcrack network becomes denser.The influence of rock type on q value is related to the burst intensity of energy release and the crack fracture mode.The q value of EPs can be used as an effective prediction index for rock failure like b value of acoustic emission(AE).The results provide useful reference and method for the monitoring and early warning of geological disasters.

Simulation and heat exchanger network designs for a novel single-column cryogenic air separation process

To realize the industrialization of the novel single-column air separation process proposed in previous work,steady-state simulation for four different configurations of the single-column process with ternary(nitrogen,oxygen and argon)is developed.Then,exergy analysis of the single-column processes is also carried out and compared with the conventional double-column air separation process at the same capacity.Furthermore,based on the steady-state simulation of single-column processes,the different heat exchanger networks(HENs)for the main heat exchanger and subcooler in each process are designed.To obtain better performance for this novel process,optimization of process configuration and operation is investigated.The optimal condition and configuration for this process is consisted as:feedstock is divided into two streams and the reflux nitrogen is compressed at the approximate temperature of 301 K.In addition,HEN is optimized to minimize the utilities.HENs without utilities are obtained for the four different configurations of single-column process.Furthermore,capital costs of the HEN for different cases are estimated and compared.

BGL气化炉新型建模方法及优化分析

充分考虑碎煤加压熔渣气化(British Gas Lurgi, BGL)炉内的流动特性,将BGL气化炉分为并流段和逆流段,并依此建立了BGL气化炉的一维稳态机理模型.并利用该模型模拟了以烟煤为原料的某工业BGL气化炉,模拟结果与工业实测值误差小于2%,从而验证该模型的正确性.然后在所得到模型的基础上探讨了氧煤比及汽煤比对气化性能的影响.研究表明,氧煤比对碳转化率以及蒸汽分解率的影响较大,随着氧煤比增加,碳转化率增大,蒸汽分解率先增大后减小,当氧煤比为0.47时,蒸汽分解率最大;汽煤比增大有利于水煤气变换反应,但该反应受化学平衡限制,当气化剂充足时,蒸汽的消耗量将小于其增加量,随着汽煤比增大蒸汽分解率逐渐降低.