Freeze the soil. In the construction of underground engineering, the soft degree and bearing capacity of various soils are different. It is often necessary to freeze the soil after construction. The conventional method is to freeze the soil with ammonia and brine, which has a history of over a hundred years. Ammonia freezing requires high management of liquid ammonia, and slight negligence can easily cause accidents in the storage, transportation and use of liquid ammonia.
Liquid nitrogen freezing is a new freezing technology, which has the characteristics of simple system, low temperature (-196 C) and high speed (10 times of ammonia salt water freezing). It began to be applied in developed countries around 1960. It plays a reinforcing and stabilizing role in the construction of underground projects, mine construction projects and emergency engineering accidents in busy urban areas. Our country has been gradually applied in the construction of projects such as Shanghai Metro since 1990s. In order to reduce the cost, the combination of conventional freezing and liquid nitrogen quick-freezing was adopted in the early stage. With the decrease of liquid nitrogen price, liquid nitrogen quick-freezing has gradually replaced. Moreover, a new method of soil layer freezing has been developed, which effectively improves the speed of ground freezing and can be used in some more difficult geology. Construction in the environment.
Fire prevention and extinguishing. Because of the ultra-low temperature, inactivity and environmental protection of liquid nitrogen, it has good fire extinguishing effect, but its cost is relatively high. At present, liquid nitrogen fire extinguishing has been used many times in coal mine engineering, and has achieved good results. It has become an important technical means to deal with large underground fire accidents. In addition, some small liquid nitrogen fire extinguishers are also used in laboratories, archives and other important places to eliminate the shortcomings of short shelf life, its fire fighting effect in the existing fire extinguishers is very good.
XINFENGLI is an enterprise specializing in the development of liquid nitrogen equipment. It is willing to develop products with various users to promote the promotion and use of liquid nitrogen.