According to our national industry standard for cables, nitrogen must be used as a protective gas when the production line of a crosslinked cable of 35,000 volts and above is produced to avoid oxidation and combustion of crosslinked polyethylene at high temperatures.

Nitrogen has always been generally two methods, from the 1960s to the 1980s, most of the use of cryogenic air separation process, with the advancement of science and technology, gradually developed PSA variable pressing nitrogen machine and the latest membrane separation nitrogen process. After entering the 1990s, the cable industry generally used membrane separation and PSA nitrogen production equipment to prepare nitrogen on site and supply production applications. The advantage of on-site nitrogen production is convenient operation and low cost. At present, there are hundreds of cable manufacturers in China using on-site nitrogen production methods.

Equipment parameter planning:

According to the cable industry standard, the purity of nitrogen is generally 99.5% (oxygen content 0.5%), the nitrogen pressure is 0.8 to 1.6MPa, and the gas consumption is planned according to the actual situation of the production line. Generally, the domestic catenation and tower line production consumption of nitrogen is 6-20nm3 /Hr, and the imported catenation and tower line is 40-60Nm3 /Hr, and the specific nitrogen consumption is determined according to whether there is a reverse bin, whether it is water-cooled or air-cooled, and the interval and time setting of exhaust gas emissions. Because nitrogen plays an important role in the production process of cross-linked cables, all aspects of the production process should be taken into account in the selection, not only to ensure that there is no fault in the production process of the cable (otherwise it will form a huge loss), but also to consider energy conservation.

Advantages of nitrogen machine in wire and cable production:

In the past, most cross-linked production line manufacturers chose bottled nitrogen, but because most bottled nitrogen is the by-product gas of other manufacturers' cryogenic oxygen production devices, most bottled nitrogen is not pure enough, and oxygen and water indicators often exceed the standard. If the water content of the medium is too high and the temperature is too high, water vapor is generated and bubbles are formed to be contained in the PE in the plastic state, which will age the PE in advance. Therefore, the selection of nitrogen gas source required for dry cross-linking production line is very important.

Nitrogen making machine adopts pressure swing adsorption (PSA) nitrogen production principle, it has the characteristics of simple process flow, normal temperature production, low energy consumption, high degree of automation, easy to start and stop, less maintenance, product nitrogen purity can be adjusted with gas volume, etc., is an efficient on-site nitrogen making system.

Due to the special requirements of cross-linked cable production, the use pressure of nitrogen is 1.2 ~ 1.6MPa, and the instantaneous gas consumption of nitrogen is large, so the nitrogen maker has designed a medium pressure storage tank to balance the fluctuation of gas. The number of medium pressure storage tanks can be configured according to the number of user production lines and production conditions.

The actual operation of PSA nitrogen production device in the cross-linked cable production line shows that the technology is advanced, high degree of automation, ADAPTS to the nitrogen demand of the cross-linked cable production line, solves the problem of nitrogen self-production and supply, and the investment is quick, and basically can recover the investment in about one year