Common Misconceptions about Drainage Issues in Steam Systems

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This post was last edited by Fulei on 2018-6-1 at 14:42. Common misconceptions regarding steam system trap issues: In steam systems, traps serve to remove water, prevent steam from entering, and expel air. The proper functioning of these traps affects steam consumption, system efficiency, and equipment lifespan, as well as the quality of the products produced. After years of field research, Fred discovered that steam users have many misconceptions regarding hydrophobicity issues. The following are some common points; please take them as a reference. A one-sided understanding of the drainage temperature: The vast majority of steam users mistakenly believe that the lower the drainage temperature of the equipment, the better, as it results in greater energy savings. However, if the drainage temperature is too low, water accumulates inside the equipment, reducing heating efficiency. To meet the process requirements, it becomes necessary to increase the opening degree of the steam supply valve and raise the steam pressure; in some cases, it is even necessary to activate the bypass of the drain valve, which ultimately leads to an increased consumption of steam. Furthermore, water accumulation can cause a temperature difference between the upper and lower parts of the heat exchange equipment, affecting the stability of product quality and the equipment’s lifespan; it can also lead to water hammer. Misconceptions about flash steam: Nearly 98% of steam users mistake flash steam for leaks; therefore, when they see \"white steam\" coming from the outlet of a steam trap, they assume it is a leak. In fact, those “white vapors” are flash vapor. When condensed water at high temperature and pressure is discharged into a low-pressure area, the total heat enthalpy remains constant while the sensible heat decreases. The heat released as a result of this decrease in sensible heat causes some of the water to vaporize, producing steam; this is known as flash steam. The generation of flash vapor is a normal phenomenon. The flash vapor flow rate is low; it appears white and can be seen at the pipe outlet ； Steam is colorless, and when a hydrophobic device leaks, these colorless gases become visible at a distance from the outlet pipe, and they emerge at a relatively high speed. Unawareness of the series connection issue for drainage: Some customers installed two drainage valves in series at the equipment outlet to prevent steam leaks caused by the failure of the drainage valve. Such problems include: 1) The condensate flashes at the outlet of the first steam trap due to pressure drop, causing vapor lock in the latter and resulting in water accumulation in the equipment ； 2) When two steam traps are connected in series, the pressure difference before and after each trap decreases; what would have been sufficient with a single steam trap of smaller diameter now requires two steam traps of larger diameter when connected in series, resulting in greater waste. Lack of understanding regarding group steam trap issues: When multiple devices or different heating sections of a single device share one steam trap, this is referred to as group steam trapping. This phenomenon is very common and can be seen in almost every client. Group hydrophobicity can cause water to accumulate inside certain heating sections of some equipment or of a single piece of equipment, which affects heating efficiency and the production process; it may even lead to equipment damage. On-site operators often resort to discharging steam directly from the equipment to \"solve the problem,\" but this comes at the cost of wasting a large amount of steam. The importance of steam system traps is greatly underestimated; in fact, they are crucial for ensuring safe operations in enterprises, improving efficiency and quality, as well as reducing energy consumption and emissions. Eliminating the misconception about hydrophobicity is the first step toward proper and effective hydrophobization. (The above article was first published on the WeChat official account “Fured Steam Energy Saving”. ）