一、进口LNG液化天然气球阀概述

进口LNG球阀是指主要用于乙烯，液化天然气装置，天然气LPG LNG储罐，接受基地及卫星站，空分设备，石油化工尾气分离设备，液氧、液氮、液氩、二氧化碳低温贮槽及槽车、变压吸附制氧等装置上，用来对低温介质LNG进行开启和关闭的阀门。

LNG ball valves are mainly used for ethylene, liquefied natural gas units, natural gas LPG LNG storage tanks, receiving bases and satellite stations, air separation equipment, petrochemical tail gas separation equipment, liquid oxygen, liquid nitrogen, liquid argon, carbon dioxide low-temperature storage tanks and tanks Valves used to open and close the low-temperature medium LNG on vehicles, pressure swing adsorption oxygen production and other devices.

LNG是英语液化天然气（liquefied natural gas）的缩写。主要成分是甲烷。LNG无色、无味、无毒且无腐蚀性，其体积约为同量气态天然气体积的1/600，LNG的重量仅为同体积水的45%左右，热值为52MMBtu/t（1MMBtu=2.52×10^8cal）。LNG是通过在常压下气态的天然气冷却至-162℃，使之凝结成液体。天然气液化后可以大大节约储运空间，而且具有热值大、性能高等特点。

The main component of liquefied natural gas is methane. LNG is colorless, odorless, non-toxic, and non corrosive. Its volume is about 1/600 of the same volume of gaseous natural gas. The weight of LNG is only about 45% of the same amount of accumulated water, and its calorific value is 52MMBtu/t (1MMBtu=2.52 x 10 ^ 8cal). LNG is condensed into liquid by cooling natural gas in its gaseous state at atmospheric pressure to -162 ℃. Natural gas liquefaction can greatly save storage and transportation space, and has the characteristics of high calorific value and high performance.

二、进口LNG液化天然气球阀性能参数

三、进口LNG液化天然气球阀特点

1.承压件的材料能承受介质温度的变化而引起的膨胀、收缩、密封部位的结构在温度变化时不会产生永久的变形。用于-100℃以下工况时，阀门零件在精加工前应进行深冷处理，即将零件浸放在液氮箱中进行冷却，当零件温度达到-192℃时，开始保温1-2h，然后取出箱外自然处理到常温，重温循环2次。

2、阀盖采用长劲结构，其目的保护填料函的功能，使填料函处于离低温较远的位置，保证填料的密封效果，同时还可以缠绕保冷材料，防止冷能损失。长颈的颈长可根据使用温度和保冷材料的厚度来选择不同的长度。当填料密封效果降低时，可以从填料函中间加入润滑脂形成油封层，降低填料函的压差，提高密封性能。

3、使用温度低于-100℃时，阀杆材料经过镀铬或氮化处理，提高阀杆表面硬度，提高填料密封的可靠性。

4、低温球阀具有防止异常升压结构，由于低温阀门介质气化后，其体积急剧膨胀，压力会异常升高，当阀门中腔压力升高时，阀门中腔和进口连通，或在阀门进口端安置泄压阀，保证阀门安全使用。

5、低温球阀用的垫片具有在常温下、低温状态及温度变化下能可靠密封性和复原性。

1. The material of pressure bearing parts can withstand the expansion, contraction, and sealing structure caused by changes in medium temperature without permanent deformation during temperature changes. When used for working conditions below -100 ℃, valve parts should be subjected to cryogenic treatment before precision machining, that is, the parts should be immersed in a liquid nitrogen box for cooling. When the temperature of the parts reaches -192 ℃, insulation should be started for 1-2 hours, and then the outside of the box should be naturally treated to room temperature and reheated twice.

2. The valve cover adopts a long stiffened structure, which aims to protect the function of the packing box, keep it far away from low temperature, ensure the sealing effect of the packing, and also wrap cold insulation material to prevent cold energy loss. The neck length of a long neck can be selected according to the temperature of use and the thickness of the insulation material. When the sealing effect of the packing decreases, lubricating grease can be added from the middle of the packing box to form an oil seal layer, reducing the pressure difference of the packing box and improving the sealing performance.

3. When the operating temperature is below -100 ℃, the valve stem material undergoes chrome plating or nitriding treatment to improve the surface hardness of the valve stem and enhance the reliability of the packing seal.

4. The low-temperature ball valve has a structure to prevent abnormal pressure increase. Due to the rapid expansion of the volume of the low-temperature valve medium after gasification, the pressure will abnormally increase. When the pressure in the valve chamber increases, the valve chamber is connected to the inlet, or a pressure relief valve is installed at the inlet end of the valve to ensure safe use of the valve.

5. The gasket used for low-temperature ball valves has reliable sealing and recovery properties under normal temperature, low-temperature conditions, and temperature changes.