金年会

化工泵的种类很多，具有耐腐性能的离心泵，磁力泵。对于特殊工况中液态烃泵的使用机械密封的选用很重要，液态烃介质是一种低温液化气体，具有低沸点、低粘度、高蒸汽压等特性。在这种工况下应用的机械密封，会使密封材料出现冷脆性，大气中的水汽会在密封装置的大气侧面上冻结，摩擦副端面液膜容易汽化等。尤其是当介质稍有泄漏，漏出的液态烃在大气侧立即汽化，带走大量热，机械密封环境温度急剧下降，使用一般的密封材料，如橡胶或聚四氟乙烯普遍变脆，导致密封失效，泄漏增大而不可收拾。

There are many kinds of chemical pumps, such as centrifugal pumps and magnetic pumps with corrosion resistance. The selection of mechanical seals for liquid hydrocarbon pumps under special conditions is very important. The liquid hydrocarbon medium is a low temperature liquefied gas with low boiling point, low viscosity and high vapor pressure. The mechanical seal used under this condition will make the sealing material appear cold brittle, the water vapor in the atmosphere will freeze on the side of the sealing device, and the liquid film at the end of the friction pair is easy to vaporize. Especially when the medium leaks slightly, the leaked liquid hydrocarbon vaporizes immediately at the atmospheric side, takes away a lot of heat, and the temperature of mechanical seal environment drops sharply. The use of general sealing materials, such as rubber or PTFE, generally becomes brittle, leading to seal failure, leakage increases and irremediable.

所以在选择液态烃泵时机械密封使用要求及注意事项很重要，有些企业采用双端面机械密封，在介质和大气端设一隔离室，其间通以封油以缓和低温的影响。但这种结构复杂且需配封液系统。据经验，使用波纹管机械密封比较好，主要表现在用属波纹管和柔性石墨代并辅助密封圈，解决了密封圈材料发生冷脆而失弹及缓冲作用的问题，如DBM型、YH604/606/609型等。

So it is very important to use mechanical seal when choosing liquid hydrocarbon pump. Some enterprises adopt double-end mechanical seal and set up an isolation chamber at the media and atmosphere end, during which oil is sealed to alleviate the effect of low temperature. But this kind of structure is complex and needs sealing fluid system. According to experience, it is better to use bellows mechanical seals, which are mainly manifested in replacing bellows and flexible graphite with auxiliary sealing rings. The problems of cold brittleness, elasticity loss and cushioning of sealing ring materials are solved, such as DBM type, YH604/606/609 type, etc.

1、金属波纹管材料选用耐低温、塑性及韧性好的哈-C,AM350，Carpenter20等;

1. Metal bellows are made of Ha-C, AM350 and Carpenter 20 with good low temperature resistance, plasticity and toughness.

2、由于在低温条件一下，摩擦副端面的汽化对机械密封，性能影响很大，除选取较合适的材料外，合理选用端面比压(主要是波纹管的压缩量，一般比通常使用中所给的压缩量大15%一30%为宜)，在机械密封元件靠近大气侧通入25℃左右的冷却水，以改善摩擦副润滑环境。

2. Because the vaporization of the end face of the friction pair has a great influence on the performance of the mechanical seal at low temperature, besides choosing suitable materials, it is advisable to reasonably select the specific pressure of the end face (mainly the compression of the bellows, which is 15% to 30% larger than the compression that is usually given in use). The mechanical seal element is put into the air side at 25 C. About the cooling water to improve the lubrication environment of friction pairs.

3、摩擦副l材料在两种特殊情况下选用:

3. Material of friction pair L is selected in two special cases:

a.对连续运转的设备，介质内若含较多的固体颗粒，此时选用“硬对硬”结构(在实际中选了YG6-YG6)较好，一般连续运转寿命8000h以上;

For continuous operation equipment, if there are more solid particles in the medium, the "hard-to-hard" structure (YG6-YG6 is selected in practice) is preferable. Generally, the continuous operation life is more than 8000 hours.

b.对间歇性的运转一设备，摩擦副选用碳化钨或碳化硅对特种石墨。

B. For intermittent running equipment, tungsten carbide or silicon carbide are selected as friction pairs for special graphite.