综合管廊燃气舱内焊接烟尘稀释研究

Study on the Dilution of Welding Fume and Dust in NaturalGas Cabin of Integrated Pipe Racks

为了消除或降低综合管廊燃气舱内管道在施工过程中产生的有害烟尘,保证作业环境有害烟尘浓度符合国家焊接烟尘极限允许浓度要求,为燃气舱内管道焊接作业提供有效可行的通风控制措施至关重要。结合氩电联焊在城市地下综合管廊燃气舱内施工过程的实际应用,采用FLUENT软件分别对自然通风工况和机械通风工况进行焊接烟尘扩散模拟,分析不同换气次数对作业人员职业健康的影响。通过分析模拟结果可知,当燃气舱内强制通风换气次数2次/h时,为项目最优烟尘稀释方案;仅利用管廊设计风口进行自然通风,根本无法达到国家焊接烟尘极限允许浓度要求;如果采取强制通风换气,应充分考虑作业人员职业健康安全与施工能耗的双重影响,进而确定最优烟尘稀释方案。对燃气管廊安全施工具有指导意义。

An effective and reasonably practicable way of providing ventilation to the natural gas cabin of integrated pipe racks during construction is required to eliminate or reduce harmful fume and dust released by pipeline welding,and ensure that the concentration of these releases stay within the maximum National allowable concentration limit on welding fume and dust.Based on actual field data of joint GTAW and SMAW welding in the natural gas cabins of urban underground integrated pipe racks,the dispersion of welding fume and dust is simulated using FLUENT software for natural and mechanical ventilation respectively.The simulation runs are used to analysis the impact of different air change rate on occupational health of the operators.From an analysis of the simulation output,it is concluded that forced ventilation of 2 air changes per hour is the optimum solution for dilution of fume and dust in the natural gas cabin.It is also found that natural ventilation via design air inlet at integrated pipe racks is not sufficient to stay below the maximum allowable concentration limit for fume and dust.The design of forced ventilation shall take into full consideration of occupational health and safety of the operators and energy consumption of the construction activities,to arrive at the optimum solution for dilution.