液态CO2防治采空区自燃应用工艺流程模拟

Simulation of application technological process of liquid carbon dioxide for goaf fire prevention and control

液态CO2具有惰化降氧、汽化降温、抑爆及扩散范围大等特点,能够有效解决采空区火源位置模糊、灭火危险大等难题。液态CO2在管道输送过程中易形成干冰或流速过快极易发生堵塞、爆震现象,制约了在采空区自燃火灾防治中的应用。在分析采空区煤自然发火特点及CO2物性基础上,确定了液态CO2通过管路直接输送到采空区的防灭火工艺流程。通过建立CO2气-液两相管道输送热力学模型,利用Aspen HYSYS V7.3软件模拟计算CO2在管道输送参数变化及影响因素,得出的管道输送距离与温度、压力、流量、内径等相互之间的关系。通过模拟确定了CO2气-液两相管道安全输送参数及现场应用工艺。在压力为2 200 k Pa,温度为-28℃,摩尔流量为75 kmole/h的条件下,管道输送内径为25.4 mm时,对应的安全输送距离不大于500 m;在内径为101.6 mm时,管道输送的安全距离不大于50 000 m.结果表明,模拟得出的输送工艺参数能够满足液态CO2防灭火系统管路直接输送过程的安全。

The liquid carbon dioxide has the characteristics of inerting,cooling,explosion suppression,wide diffusion range etc,it can effectively solve the difficulties of gob fire source position fuzzy and put out fire risk. Liquid CO2 is easy to form carbon dioxide ice or when the velocity too quickly,easily occurs the phenomenon of jams and detonation in the process of pipeline transportation,which restrict the application of carbon dioxide in the coal seam spontaneous combustion fire prevention. Based on the characteristics of goaf coal spontaneous combustion and properties of CO2,the fire prevention technological process of the liquid carbon dioxide for the gob is determined. The thermodynamic model of carbon dioxide gas-liquid two-phase pipeline is established. Using Aspen HYSYS V7. 3 simulated the pipeline transmission and influencing factors of carbon dioxide,and obtained the relations of transmission distance and temperature,pressure,molar flow,inner diameter. Through numerical simulation,CO2gas-liquid twophase pipeline safety transportation parameters and the on-site application technology were determined.Under the condition of the pressure 2 200 k Pa,temperature 28 ℃,molar flow rate 75 kmole / h,when the pipeline diameter is 25. 4 mm,the corresponding safety transportation distance is not more than 500 m;when the pipeline diameter is 101. 6 mm,the corresponding safety transportation distance is not more than 5 000 m. Field application shows that the process parameters by simulation can satisfy the safety of the pipeline direct transport process of liquid carbon dioxide for fire prevention and control.