Narrow On-Site Space Renders Core Extractor Unusable for Heat Exchanger Core Extraction: Clever Solution Overcomes the Dilemma, New "Weapon" Boosts Efficiency

Core Sampling in a Narrow Gap

During the construction of the first catalytic unit at Dongxing Petrochemical, the Third Inspection Team encountered a major obstacle. The space for extracting the core of the heat exchanger in the fractionation area was extremely limited, with a passage only 7 meters wide. The heat exchanger tube bundle measured over 6 meters, and the core extractor 9.8 meters—both lengths were almost longer than the passage, making the core extractor completely unusable. They had to resort to the traditional method of core extraction using a winch.

However, when using the winch, appropriate anchor points (pulleys) needed to be arranged for core extraction of heat exchangers on different planes. Locating these anchor points was time-consuming, and for each heat exchanger tube bundle disassembled, the terminal anchor point had to be moved to the same horizontal position as the heat exchanger, resulting in slow construction progress.

To solve this problem, accelerate the construction schedule, and ensure the achievement of key project milestones, An Feiya, Deputy General Manager of the Third Inspection Team in charge of the project, Huang Guangyu, monitor of the 8th Maintenance Team specializing in heat exchanger overhauls, and Ke Hanxing, a senior exchanger technician, conducted in-depth discussions and research. They decided that the M-type anchor point arrangement was the optimal solution.

After successful testing and commissioning, this method finally resolved the issue of being unable to use the core extractor for heat exchanger core extraction in the narrow on-site space. The 12 most difficult-to-disassemble tube bundles were gradually pulled out of the shell through the action of multiple anchor points with the winch. With the assistance of a crane, vertical or inclined hoisting was then adopted to overcome the space constraints and complete the core extraction process—truly a dramatic "core sampling in a narrow gap."

The arduous process of core extraction from a narrow gap

The position of the heat exchanger tube bundle and the process of it being pulled out of the shell are shown in the figure. It can be seen from the figure that the space where the heat exchanger is located is extremely narrow.

Let the Horizontal Tank Navigate Through the Pipe Forest

During the replacement and installation of the catalytic gas liquid separator tank, the Third Inspection Team encountered a major challenge. Due to the narrow site, undersized access roads, and low pipe racks (only 3.9 meters high), the separator tank—with a diameter of 3.6 meters and a weight of nearly 8 tons—could not be directly transported to the installation site by flatbed truck. Its total height, including the base, already exceeded the height of the pipe racks.

Using a crane for overhead lifting was also unfeasible. The cramped site forced the crane to be positioned at the lower end of a T-junction, within the 90-degree angle between two units. The crane’s boom had an excessively small turning radius, and any rotation would be blocked by the unit frames.

To solve this problem, the construction team from Baiyun Electric Co., Ltd. and the hoisting personnel of the Heavy Machinery Branch brainstormed solutions. Addressing the issue that the vertical height of the tank body plus its base exceeded the pipe rack height, they used two cranes—one positioned to the east and the other to the south. Through collaborative operation, the cranes flipped the tank body and its base from a vertical state to a horizontal one, allowing it to just pass through the pipe racks.

Subsequently, the crane positioned to the east adjusted the tank’s orientation from east-west to north-south. It then slowly transported the tank under ultra-low altitude to pass through the pipe racks. After the tank had cleared more than half of the pipe racks, the crane stationed to the north took over, lifting the tank completely out of the pipe rack area and delivering it to the hoisting point.

The entire movement was carried out at an ultra-low altitude, close to the ground. All coordinating personnel proceeded with extreme caution—preventing the tank from touching the ground while also avoiding collisions with surrounding pipelines and equipment during its sway. The whole process was just like a giant navigating through a T-shaped path in a pipe forest.

The Scene of the Tank Passing Through the Pipe Racks at Ultra-Low Altitude with the Cooperation of Two Cranes

The team members of the Third Inspection Team have always been experts in tackling tough challenges. This time, they overcame difficulties such as narrow construction sites, difficult equipment transportation, limited operation space, and extreme heat. They turned the impossible into possible, ensuring that the replacement and hoisting of the liquid separator tank as well as the high-difficulty core extraction work were completed on schedule.