How to choose more suitable drain valve products

On the drain valve of UK * chemical industry company in Huddersfield and Grangemouth (England) industrial plant The performance has been monitored and tested for up to 7 years On the basis of the performance and fresh steam loss monitoring and experiments conducted by two manufacturers' laboratories, Zui, a British chemical industry company, has finally modified the selection of drain valves in its engineering design guide There are many disadvantages in the old selection standard Zui obviously does not mention the type of the equipment to be drained and the drainage method The selected drain valve often does not match the actual load In particular, the hot power disc drain valve (the basis of the old selection standard) is mistaken as a drain valve by people, especially workshop personnel As early as 1980, Grangemouth plant began to monitor the performance of the main steam trap due to complaints from engineering maintenance personnel about its short service life Two years later, the Huddersfield plant did the same In the monitoring, first of all, the investigation of the drain valve is made to understand the types of the existing drain valve, and check the load when selecting the type At the same time, the related tests were carried out The preliminary results were startling The test results of 415 steam traps in a workshop show that 19% of them are effective and 63% of them are not suitable for the load selection The test of 132 steam traps in the main steam pipe shows that 42% of them are effective The inspection of the service life of the drain valve started in 1980 and has been continued up to now In order to test the energy-saving benefits of various traps, the fresh steam loss test was carried out for the traps being used in the laboratories of two manufacturers The test is carried out in laboratory condition, i.e at 20 ℃, still air This experiment did not detect the heat loss of the valve body During the test, the condensate load is 10-20 kg / h (22-44 lb / h) As a general-purpose hot dynamic disc type drain valve widely used in Zui, its energy-saving effect Zui is poor, and compared with the inverted bucket drain valve, its service life is very short In the case of low heat requirement, replacing the thermal power disc drain valve with the thermal static drain valve will improve the energy saving effect and ensure the service life These experiments also reveal that mechanical traps (i.e inverted bucket and floating ball traps) can ensure that the steam does not contain condensed water no matter the load of condensed water is large or small, while the thermal static traps tend to accumulate condensed water when the load is increased In addition, the bimetal drain valve is easy to be unstable The revised new guidance includes the selection table of drain valve Current model selection recommendation: inverted bucket drain valve: as a drain valve for all process loads and steam main lines, that is, all occasions requiring steam drainage Floating ball thermo static drain valve: it is used for process drainage, especially in the application where the control load is less than 3.5kg (50psig), or where the air content is high, and the installation of inverted bucket drain valve has problems Balanced pressure drain valve: used as unimportant heat tracing or heating system Bimetal thermal static drain valve: used for low temperature or frost proof condition of heat tracing pipeline or heating system This type of drain valve can make full use of the sensible heat in the condensate or prevent the product from overheating Its valve body is all stainless steel Thermal power disc drain valve: as long as its performance is proved to be good by previous experience, it can be used as an alternative product of inverted bucket drain valve, and it can be used on the steam main pipe and heat tracing pipe with a pressure of less than 17 kg, or it can be used as a product to replace it with a higher steam pressure It is not recommended because of its low energy efficiency and short service life.