城镇燃气管道低温工况下材料选用分析

为了研究低温工况下城镇燃气管道的材料选用问题,本文分析了架空管道、调压、放散、排污等几种典型工况,提出了确定最低设计温度的方法。低温工况材料选用时,其最低使用温度和冲击功试验温度不应高于最低设计温度,并需要对材料提出冲击韧性要求。研究结果提示可以通过适当增加壁厚使管道处于低温低应力工况而降低材料要求。

常见天然气设备用气量估算

近年来,北京市燃气集团有限责任公司(以下简称“北京燃气集团”)积极响应北京市政府要求,全方位提高服务质量,向社会推出“小微工程”服务模式,优化办理流程、精简办事材料,压缩审批时间,在满足一定市政条件下免费为用户安装燃气设施,接通管道天然气。在燃气“小微工程”实践中,经常遇到各类民用燃气设备,如家用灶具、家用燃气热水器、家用采暖壁挂炉、商用灶具、采暖锅炉等设备。这些设备参数往往标注的是功率、热水量、吨位等,并不直接给出天然气用气量,无法直接进行气量核算和给出供气方案[1][2]。本文从本人的实际工作出发,首先分析了常见的几类民用天然气设备,从设备的工作原理出发,依据其标注的设备参数,计算其用气量并给出估算方法,可便于“小微工程”管理人员现场踏勘时选择气源管线,确定供气方案,也可供其他燃气工程管理人员参考。

Mutual Inductance Calculation Between Arbitrarily Positioned Polygonal Coils

Polygonal coil systems are designed for increasing and more kinds of sensors and electromagnetic systems.This paper presents a method for calculating mutual inductance between polygonal coils including irregular polygons.Based on the Biot-Savart law,the method calculates mutual inductance by dividing a polygonal coil into finite wires,and expresses the magnetic induction intensity generated by the excitation coil as a function of the spatial position of each vertex of the coil.The calculation method of the feasible region of the objective function is updated and the calculation process is simplified,so the calculation accuracy is improved.For octagon coils arbitrarily positioned in space,the accuracy of the algorithm is verified by the simulation and experiment.