Shell and Tube Heat Exchanger

Shell and Tube Heat Exchanger

1. Shell and Tube Heat Exchanger Introduction

Shell and tube heat exchangers are the most widely used type of heat exchanger. At present, most of the oil coolers, fresh water coolers, fuel heaters, condensers, etc. used on ships are shell and tube types.

There are many structural forms of shell and tube heat exchangers, but there are three basic types: fixed plate tube type, U-shaped tube type and floating head type.

Shell and Tube Heat Exchanger
5~270kW Electric Heater For Oil and Water	19~108kW Electric Heater for Jacket Water	270kW Electric Heater with Control Cabinet and Pump	15~486kW Electric Heater for Water
10~5000kW U-tubes Oil and Water Cooler	400~6000Kg Straight-tubes Oil Cooler	120m³ Straight-tubes Tank Cleaning Heater	300~2000kW U-tubes Cargo Heater

①Fixed plate and tube heat exchanger

The picture shows a fixed plate and tube heat exchanger, which is mainly composed of a shell 3, front and rear covers 5, and heat transfer tubes 1 fixed on the tube sheet 2. Two fluids for heat exchange, one flows through the heat transfer tube, and the other flows through the shell. In order to increase the flow rate and flow rate of the fluid in the housing, multiple transverse partitions 4 are arranged in the housing, and the flow conditions of the two fluids are shown in the figure.

The characteristic of the fixed plate tube heat exchanger is that the tube plates at both ends of the tube bundle are fixed on the shell, and the structure is simple and easy to manufacture. However, because the tubes, tube sheets and shell are rigidly connected, when the two fluids are relatively When there is a large temperature difference, due to uneven expansion between the shell, tube and tube sheet, leakage may occur at the connection. Therefore, it can only be applied to occasions with a small temperature difference. In addition, since the tube bundle cannot be extracted from the housing, it is difficult to clean the outer wall of the tube.

②U-shaped tube heat exchanger

In order to overcome the shortcomings of leakage due to uneven expansion, the straight pipe is changed to a U-shaped tube, and the two nozzles are fixed on the same tube plate, thus forming a U-shaped tube heat exchanger, as shown in the figure.
The characteristic of U-tube heat exchanger is that the tube can expand freely in the shell, and the tube bundle can be drawn out of the shell, which is convenient for cleaning the outer wall of the tube. However, the dirt on the inner wall of the tube is not easy to clean. In addition, the U-shaped tube is surrounded by layers. Yes, if the inner tube is damaged, it cannot be replaced.

U-shaped tube heat exchangers are suitable for occasions where the temperature difference is large and the fluid in the tube is relatively clean, such as fuel heaters, fuel injector fresh water coolers, etc.

③Movable Tube Sheet heat exchanger
The movable tube sheet heat exchanger is an improvement of the fixed plate and tube heat exchanger. If one end of the heat transfer tube 1 is fixed to a movable tube sheet 6 which is slightly smaller than the inner diameter of the shell, when the heat transfer tube bundle is heated and expanded, the tube sheet can slide along the axial direction of the shell 3, in order to prevent cold and heat For mutual leakage of fluids, packing 7 is installed on the outer periphery of the movable tube sheet and compressed with a pressure ring 8.
Compared with fixed heat exchangers, movable tube sheet heat exchangers have two major advantages: one is that the movable tube sheet can slide in the shell, which reduces the possibility of leakage due to uneven expansion; the other is that the tube bundle can be removed from the shell. Withdraw, it is easy to clean the outer wall of the tube. Because the movable tube sheet heat exchanger has the above advantages, it has good adaptability to working fluid and can work reliably under a large temperature difference, so it has been widely used, mainly used as main engine oil cooler and main engine fresh water cooler.

Heat Exchangers in workshop