Main steam valve of steam turbine

Abstract

The invention discloses a main steam valve of a steam turbine. The main steam valve comprises a valve body, a bonnet and a valve stem, wherein an upstream steam passage, a downstream steam passage, a valve stem assembly hole, a bonnet assembly hole and a valve seat are formed on the valve body. The bonnet mainly comprises an inner bonnet, an elastic sealing ring, a hold-down ring and a locating ring which are arranged in the bonnet assembly hole from the bottom up in sequence, and an outer bonnet which is fixed at the outer end of the bonnet assembly hole through fixing bolts, wherein the inner bonnet is subjected to self-tightening seal and bears most pressure, the outer bonnet bears less pressure, and the sealing effect is good. The upper end of the valve stem passes through a sleeve and is connected with a valve disc, and under the operation of the valve stem, the valve disc is matched with the valve seat to close or open the upstream steam passage and the downstream steam passage on the valve body. A sealing cartridge is arranged on the sleeve, and a sealing cone is arranged on the valve stem. When the valve disc and the valve seat are open, the valve stem is sealed with the sealing cartridge through the sealing cone, and the opening of the valve disc is limited by the sealing cone. The main steam valve has the characteristics that the main steam valve is good in sealing performance, low in production cost, high in practicability and capable of bearing high parameter steam.

Description

technical field [0001] The invention relates to a steam turbine, in particular to a main steam valve of a steam turbine. Background technique [0002] The main steam valve of the steam turbine is the first valve of the steam turbine. Through the opening and closing of the main steam valve, the supply and cut-off of the steam of the steam turbine is realized. Therefore, the main steam valve operates in a high-temperature and high-pressure steam environment for a long time, and the main steam valve is required to have good performance. Sealing to prevent high-temperature and high-pressure steam from leaking, causing heat energy loss, and even safety accidents. [0003] see figure 1 : The traditional steam turbine main steam valve includes a valve body 08, a valve cover 010 and a valve stem 01. Among them, the valve body 08 is an inner hollow structure, and the valve body 08 is provided with an upstream steam channel 012, a downstream steam channel 013, a valve stem assembly ...

AI Technical Summary

Problems solved by technology

The main steam valve caused a large amount of high-quality steam to leak into the low-level steam system through the annular space between the valve stem 01 and the sleeve 02, causing a certain loss of heat energy and increasing the operating cost of the steam turbine. More prominent on supercritical units or double reheat units

In order to reduce steam leakage, the conventional method is to install a steam seal sleeve 03 on the valve stem 01 in the sleeve 02. Although this method can play a certain role in plugging leakage, the effect is very small, and there is still a large amount of high-quality steam leakage. , poor reliability

[0004] In addition, the bonnet 010 of the above overall structure is completely sealed and assembled on the bonnet assembly hole of the valve body 08 by means of fastening bolts 011. It is also particularly prominent on the ultra-supercritical unit or the double reheat unit. In order to ensure the reliable sealing and fixing strength of the valve cover 010, the fastening bolt 011 is required to have good structural strength, and the structural strength of the fastening bolt 011 is improved. It is achieved by upgrading the material of the fastening bolt 011 and increasing the specification (including diameter and length), which not only increases the manufacturing cost of the main steam valve, but more seriously, with the fastening bolt 011 The increase in the number of fastening bolts increases the difficulty of design and processing of the fastening bolts. Blindly increasing the fastening bolts of the bonnet will inevitably cause damage to the structural stress of the bonnet and the valve body, thus making the design of the entire main steam valve , The difficulty of processing increases, the service life is shortened, the manufacturing efficiency is reduced, and the manufacturing cost of the enterprise is significantly increased

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