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New Industrial Waste Helium Gas Purification and Recycling

Date: Apr 03, 2024

Background Introduction

Helium is a scarce strategic resource that, apart from a few regions globally, is relatively rare. However, helium has a wide range of uses, serving as a crucial resource in military reconnaissance airships, industrial fibers, semiconductors, air conditioning, welding, and other high-end manufacturing sectors. The diplomatic collapse in Qatar in 2017 once again severely impacted the normal supply of helium worldwide. Yet, in the industrial field, helium is generally not purified and recycled but is used consumptively and then directly released into the atmosphere, leading to significant wastage. Therefore, conducting comprehensive research on helium purification and recycling technology in the industrial sector has once again become a focal issue of industry attention.

Technical Features

The common method for helium purification and recycling equipment is cryogenics, using the condensation method. Moreover, during the development of the equipment, a multitude of new technologies in the field of cryogenics were applied, including vibration reduction for high-pressure helium compressors, special welding technology for low-temperature, high-pressure copper pipes, and sealing technology for low-temperature, high-pressure unions, all aimed at optimizing the product. Building on this foundation, a breakthrough in purification technology using membrane separation was achieved. Through a composite purification and separation method, helium gas with a purity of≥10% is purified to over 99.5%, with a system purification recovery rate of≥60%. This process technology purifies raw gas containing≤50% ammonia online to supply back >99.999% high-purity helium gas, overall saving more than 55% of helium usage.

Helium purification is an area of cutting-edge international research, employing methods such as cryogenic condensation, membrane separation, pressure swing adsorption, and chemical adsorption. Based on their foundation in cryogenics, Chinese companies have broken through the technological bottlenecks of cryogenic condensation separation, developing industrial helium membrane separation purification technologies and equipment. This positions them in competition with international giants in the field of helium purification technology and equipment. Moreover, they are actively researching composite helium separation methods that combine membrane separation with cryogenic separation. By integrating the efficiency of membrane separation and the high recovery rate and purity of cryogenic separation, helium is first coarsely purified using membrane separation technology, followed by fine purification through cryogenic separation technology. This approach meets the industrial sector's multiple needs for energy saving and high purity.

Application Scope

Helium is primarily used in the fields of healthcare, military, refrigeration, semiconductors, pipeline leak detection, high-precision welding, metal manufacturing, deep-sea diving, optoelectronic product manufacturing, balloon transport, scientific research, and other military applications. The following analysis focuses on the main uses of helium resources and their users.

(1) Nuclear Magnetic Resonance (Low-Temperature Superconductivity) Field

Nuclear Magnetic Resonance Imaging (MRI) systems, which use low-temperature superconducting magnet technology, require liquid helium for cooling. According to statistics, MRI systems account for 34% of global helium usage, making it the largest end-use industry. Although the demand for MRI systems is decreasing in developed countries, the demand in developing countries continues to grow strongly, maintaining a robust demand for liquid helium.

(2) Refrigeration (Home Appliances) Field

Helium is primarily used in condensers, evaporators, and pipeline systems for leak detection.

(3) Semiconductor and Fiber Optics Field

Helium is mainly used in the semiconductor industry as a protective gas for the growth of germanium and silicon crystals, and in the production of preforms for optical fibers and the fiber drawing process as a cooling and protective atmosphere gas.

(4) Welding Protective Gas

Purpose: When certain metals are heated or melted, it is necessary to prevent them from reacting with oxygen and nitrogen in the atmosphere by using an inert atmosphere for protection. A significant amount of helium is consumed in metal welding processes. In tungsten inert gas welding (TIG), where the tungsten electrode does not melt, the hot metal filler and the welding area must be protected with a continuous flow of helium or a helium-argon mixture. The gas mixtures used for protective welding can be prepared with helium and argon in various proportions. Depending on the welding process, the welding wire, and the base material being welded, the composition of the mixed gas can vary, with helium content in helium-argon mixed gas typically ranging from 15% to 70%.

(5) Cryogenic Engineering Field

Usage: Due to helium's chemical inertness and extremely low liquefaction point, it behaves nearly as an ideal gas at all temperatures except very low ones. With its high specific heat capacity, low viscosity, and high thermal conductivity, helium is commonly used as the working medium in closed-cycle cryogenic refrigerators, as the cooling medium for superconducting magnets and cavities in major national scientific projects, and in academic and research experiments.

(6) Aerospace Field

Usage: In the fuel systems of rockets and spacecraft, helium is used to purge low-temperature fuel and oxidizer tanks and pressurize the space above the liquid in low-temperature storage tanks to provide the pressure necessary for the direct transfer of liquid hydrogen and liquid oxygen or to provide a positive net suction head for the pumps. Helium is commonly used as the working medium in pneumatic control systems. Before the launch of a rocket, to achieve maximum propulsion efficiency in the first few minutes of ignition, cryogenic helium is used to pre-cool the upper stage liquid hydrogen rocket engine. Liquid helium is also widely used in cryogenic radiation detectors and for other specialized instruments in space exploration programs.

(7) Balloon Lift (Aerostats)

Usage: Helium is filled in civil or military aerostats, airships, and balloons.

(8) Automotive Manufacturing Field

Usage: Helium is used in automotive airbags, for leak detection in the airtightness of aluminum alloy wheels, in the airtightness testing of car air conditioning evaporators, compressors, and condensers, and in the application of helium in laser welding of car frames.

(9) Other Fields

Physiological healthcare, nuclear reactors, electro-optical sources, metallurgy, metal processing technologies, and as a carrier gas in analytical testing. Helium in these applications is generally not recovered.

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