Current Status & Future of Cryogenic Pumps
In recent years, natural gas has steadily increased its share of global energy consumption, positioning itself alongside oil and coal as one of the three main pillar energies. Liquefied Natural Gas (LNG) is recognized worldwide as a clean energy source, offering numerous benefits including energy efficiency, environmental friendliness, safety, reliability, and economic advantages. In China,the national "12th Five-Year Plan" has encouraged the development and introduction of LNG. By 2012, China had established 12 LNG import terminals in coastal cities, with a total capacity of 35 million tons, exceeding the combined volume of the West-to-East Gas Pipelines' first and second lines. The rapid development of LNG liquefaction technology in China has been supported by the "13th Five-Year Plan," which aims to achieve a natural gas supply capacity of 360 billion cubic meters by 2020, accounting for 8.3% to 10% of primary energy consumption.
China primarily imports natural gas in the form of LNG. The LNG production and consumption process involves several key stages: liquefaction, transportation, receiving, transport, and sales. LNG cryogenic pumps play a crucial role in each stage of the LNG supply chain.
Currently, only a few companies globally produce LNG cryogenic pumps, and China's LNG production is in its infancy. Domestic LNG liquefaction plants, receiving terminals, vaporization stations, and LNG vehicle refueling stations mainly use Western products, which are expensive and have long delivery times. In line with national policies to develop the LNG industry and ensure energy security, there is an urgent need to develop domestic LNG transfer pumps.
Current Status and Development Trends
International Technology Status
The United States began industrial-scale natural gas liquefaction research as early as 1910 and started LNG production in 1917. Subsequently, developed countries like the UK, France, and Japan entered the LNG trade. The U.S. has a nearly 100-year lead in low-temperature pump technology research compared to China. Major international low-temperature pump manufacturers include EBARA (USA), NIKKISO (USA), and JC-CARTER (acquired by NIKKISO). These companies have decades of experience in product development, manufacturing, testing, and operation, with a trend towards developing large, efficient, and reliable products.
Domestic Technology Status and Trends
With rapid advances in basic research and engineering technology in China, domestic manufacturers of cryogenic pumps have conducted research and applications in low-temperature materials, submersible motors, inlet bottom valves, electrical components, and low-temperature bearings. Significant progress has been made in low-temperature testing technology and safety monitoring. However, a complete set of design, manufacturing, testing, and engineering application technologies is still lacking, and there remains a gap in engineering experience compared to foreign manufacturers. Continuous application and experience accumulation are required to bridge this gap.
LNG Pump Structure and Features
LNG cryogenic submersible pumps consist of components such as low-temperature submersible motors, impellers, guide vanes, bearings, and thrust balance structures. These pumps are centrifugal in design, meeting the -196°C temperature requirements with excellent anti-cavitation performance. Key components, such as the motor, are cooled directly by LNG and operate in an oxygen-free environment, eliminating explosion risks. Bearings in submersible pumps are exposed to extreme low temperatures and use silicon nitride ceramic ball bearings for stability.
Advantages of Submersible LNG Pumps
> Sealless Design: Eliminates the risk of shaft seal leakage.
> Stable Temperature: Motor cooling by LNG maintains stable temperature without explosion risk.
> Low Noise: The entire pump is immersed in liquid, resulting in low operational noise.
> Simple Structure: Coaxial motor and impeller design ensures high reliability.
>Extended Bearing Life: Built-in balance mechanisms reduce axial forces.
>Self-Lubricating Bearings: Bearings are lubricated by the medium, eliminating the need for additional lubrication systems.
Submersible LNG pumps have seen widespread success in applications such as large LNG carriers, vehicle refueling stations, and LNG receiving terminals.
Domestic R&D Directions for LNG Submersible Pumps
The overall goal for domestic LNG submersible pump R&D is to develop a series of large-flow LNG cryogenic pumps that meet international standards for technology level and operational reliability. Key research areas include:
> Hydraulic Technology: Develop high-flow, efficient, low-cavitation impellers suitable for LNG, and optimize hydraulic design to match imported pump curves.
> Bottom Valve Development: Optimize domestic bottom valve designs for sealing, strength, interchangeability, and general usability.
> Low-Temperature Material Research: Study materials for low-temperature strength and deformation, and develop materials for low-temperature motors.
> Lubrication of Low-Temperature Bearings: Address lubrication challenges in LNG pumps using the low-viscosity LNG as a lubricant.
Future Trends and Outlook
China's LNG import volume has nearly doubled in the past five years, and by 2022, the total capacity of LNG receiving stations in China is expected to exceed 13 million tons per year. With a favorable supply of global LNG resources and strong domestic demand, China's LNG market has a promising outlook. The construction of additional LNG receiving stations will drive the increasing demand for LNG pumps. Future development will include pumps for other cryogenic media such as ethylene, propane, and liquid nitrogen. The advancement of clean energy policies in China will further enhance the market potential for domestically developed LNG submersible pumps.
Key research areas for the future include low-temperature materials, lubrication of bearings under low temperatures, characteristics of low-temperature motors, and testing technologies for LNG pump media.
