In recent years, the National Research Institute of Mechanical Engineering (Narime) has gradually researched, decoded and mastered the technology of designing and manufacturing heat exchangers.

Research and mastery of technology

The research, decoding and mastery of technology for designing and manufacturing heat exchangers opens up the possibility of replacing many imported equipment, enhancing the autonomous capacity for the domestic industry.

Sharing with a reporter of the Industry and Trade Newspaper, Dr. Phan Dang Phong, President of the National Research Institute of Mechanical Engineering (Narime) said that in the operation of hydropower plants, the oil and air cooling heat exchangers play a role as equipment maintaining the stability of the entire generating unit.

Although not in the group of main equipment, their performance directly determines the lifespan and continuous operation capability of the Generator, transformer, bearing system, guide bearing and key auxiliary assemblies. Previously, most of this equipment was imported synchronously; when replacement, repair or spare parts procurement was needed, investors often depended on foreign manufacturers for technical documentation, with long delivery times and high costs.

In recent years, the National Research Institute of Mechanical Engineering (Narime) has gradually researched, decoded and mastered the technology of designing and manufacturing heat exchangers. A notable point is that Narime did not approach by copying the shape of the equipment, but started from actual operational requirements at the plant: Calculating heat balance, selecting materials, determining flow cross-section, designing heat exchange tube structure, building sealing weld solutions and pressure testing before putting the equipment into use.

Through research, the technical parameters of the heat exchangers show that the products can meet technical requirements equivalent to imported equipment of the same type. To achieve this level, the design stage must simultaneously control many factors: Heat transfer capacity, pressure loss, medium cleanliness, temperature fluctuations, joint tightness and tube bundle durability under continuous working conditions.

"One of the products demonstrating Narime's technology mastery capacity is the transformer oil cooler, which has been installed at hydropower plants such as Hoa Binh, Ialy and many other projects. For this equipment, the requirement is not only to manufacture the correct dimensions for replacement installation, but also to ensure heat exchange efficiency, tightness, pressure resistance and stability during long-term operation" - Dr. Phan Dang Phong said.

According to Dr. Phan Dang Phong, to manufacture this equipment, Narime conducted a deep research process, including: analyzing the tube bundle heat exchange structure; optimizing the flow of oil and water; mastering the manufacturing technology of heat exchange tubes and pressure-tight welded joints; controlling thermal stress, deformation and durability during long-term operation. The equipment must also be suitable for operating conditions in Vietnam, where ambient temperature, cooling water quality and plant load can vary significantly by season and power system load.

"Each plant has different operating conditions, so the equipment is designed for each project, rather than mass-produced according to a fixed design. This approach helps the new equipment be compatible with the existing installation space, utilize the existing piping and connection assemblies, while minimizing downtime during replacement" - the President of the National Research Institute of Mechanical Engineering said.

To date, the heat exchangers researched, designed and manufactured by Narime have been applied at more than 29 domestic hydropower projects such as Hoa Binh, Son La, Tuyen Quang, Tri An, Thac Mo, Ban Chat, Buon Kuop... The deployment of products for operation at many plants is an important testament to the ability to transfer research results into industrial equipment with specific application addresses.

Cost reduction of at least 30% compared to imported ones

Dr. Phan Dang Phong shared that the biggest difficulty in the research process was not in manufacturing a single mechanical component, but in mastering the entire design problem of heat exchange equipment without having full original design documents. The research team had to survey existing equipment, take field measurements, analyze materials, evaluate the plant's load regime and reconstruct the calculation parameters so that the new equipment could be installed as a replacement, while being suitable for actual operating conditions.

In addition, the transformer oil cooling equipment works simultaneously with two media: oil and water, so the requirements for tightness and safety are very high. Even a small deviation in the calculation of flow rate, heat exchange area, tube structure or weld quality can affect the cooling performance and reliability of the generating unit. Therefore, the design and manufacturing process must be accompanied by pressure testing, leak testing, material quality control and strict acceptance before handover to the plant.

With these research efforts, the successful localization of heat exchangers brings practical benefits to investors such as: Cost reduction of at least 30% compared to the imported option; shortened repair and maintenance time; proactive supply of replacement spare parts; while reducing the risk of dependence on foreign suppliers in situations requiring quick handling at the plant.

More importantly, this result is not limited to a specific product, but also forms the capacity for calculation, design, manufacturing, testing and integration of equipment according to the requirements of each project. This is the foundation for Narime to continue developing mechanical products with higher technical requirements in the energy and industrial fields.

"From heat exchangers, Narime is expanding its capacity to auxiliary equipment assemblies, replacement equipment and integrated systems serving energy plants. This is a direction consistent with the requirements of domestic mechanical development: Not only manufacturing components, but gradually mastering design, integration and after-sales technical services" - Dr. Phan Dang Phong added.

In the context where many power plants and industrial plants are entering the period requiring overhaul, upgrade and equipment replacement, mastering products such as heat exchangers has very practical significance. It is a way to reduce costs, proactively manage repair schedules, increase the localization rate and gradually build technological autonomy for Vietnam's mechanical engineering industry.

Source: Industry and Trade Newspaper