After two days of inspection, the customer representative measured the dimensions and inspected the water pressure testing process of the tube bundles.  The 14 sets of air cooler tube bundles use copper pipes and aluminum fins, which can better increase heat exchange efficiency.

Air cooled heat exchanger (hereinafter referred to as "air cooler") is a heat exchange equipment that uses air as the cooling medium to cool the process medium (heat flow) to the required temperature. Generally speaking, in industry, when the medium temperature is below 120 ℃, the cost of heat recovery is relatively high or it is difficult to comprehensively utilize due to the dispersion and intermittency of the heat source. Most of this heat is discharged into the atmosphere after heat exchange through air coolers.

In petrochemical refining projects, with the increasing scale of the equipment, in order to achieve the required cooling effect for the corresponding processing capacity, with a certain cooling efficiency of the single air cooler, the requirement can only be met by increasing the number of air coolers. Due to the increase in the number of air coolers and the increase in the diameter of the air cooler outer connecting pipe - the collection pipe, the piping design of the air cooler has become increasingly difficult. Especially as a sensitive equipment, the allowable force of the outer connecting pipe of the air cooler is very small. How to ensure the safe operation of the air cooler while meeting the requirements of its piping design has become one of the very important topics in modern industrial design.

Introduction to the Basic Structure of Air Cooler and Air Cooler Tube Bundle

The air cooler is mainly composed of five basic components: tube bundle, fan, frame, louver, ladder platform, etc. Its basic structural form is shown in Figure 1. The main impact on the piping design of the air cooler is the tube bundle part of the air cooler. The tube bundle is composed of heat transfer tubes (finned tubes or smooth tubes), tube boxes, side beams, inlet and outlet tubes, etc. Its basic structural form is shown in Figure 2. The inlet pipe is connected to the front pipe box; The process medium enters the tube box through the inlet pipe and is distributed to each finned tube through the tube box. After completing heat exchange inside the finned tube, it flows out through the outlet pipe; Both the front and rear pipe boxes are supported on the lower support beams of the pipe bundle.

When the process medium enters the air cooler, the thermal expansion in the width direction of the tube box and the length direction of the finned tube will cause displacement of the tube bundle. For multi-stroke tube bundles, the temperature difference between each stroke will also cause relative displacement. If no measures are taken, it will cause accidents such as bending and cracking of the heat transfer tube, deformation and damage of the structure, and leakage of the expansion port. Therefore, when calculating thermal expansion and designing thermal compensation for the air cooler tube bundle, the following principles should generally be followed:

1) There must be one end between the tube box of any tube bundle and the tube bundle frame channel steel that can freely expand and contract along the length direction, and there should also be a thermal expansion gap along the width direction of the tube box.

2) Determine the fixed and free ends of the tube bundle, and only allow the tube bundle to slide towards the free end for thermal displacement. Generally, one end of the inlet and outlet pipelines is used as the fixed end. For a single tube bundle, unless there are special requirements, the inlet pipe box is generally determined as the fixed end.

3) Using the tube bundle side beam as a fixed base. Tighten the connection between the fixed-end pipe box and the side beam in the length direction of the pipe bundle. The free-end pipe box only relies on the side beam for gravity support, but should allow the support points to slide in the length and width directions.