Coil heat exchangers: used in liquefaction systems. One of the three classical heat exchangers used in large-scale liquefaction systems today is the coil heat exchanger [CTTHE], whose structure is described in references [5] and [9]. The structure of the heat exchanger comprises helically coiling a large number of ductile tubes of small diameter around a central tube, a heat exchanger having a plurality of tubes in the direction of the principal axis and in the radial direction, one or more tubes Can be combined together into one or more tubesheets through which different fluids can flow in countercurrent flow to a single shell side fluid.
The high pressure flow path flows in the small tube while the low pressure reflux steam flows in the annular space between the central tube outside the tube and the case. By using equal length heat transfer tubes and varying tube spacing in these different layers, the pressure drop across each high pressure flow path within the coil can be made equal. Due to the fact that both sides of the envelope have small diameter tubes, the coil heat exchangers can not be mechanically cleaned to handle solids-free fluids or fluids that can be chemically cleaned. Low-temperature fluid can be used to deal with aluminum alloy material, high temperature fluid treatment using stainless steel.
Coil heat exchangers have unique advantages and are particularly suitable for cryogenic fluids that handle the following situations [50:
1. Two or more fluid at the same time heat transfer;
2. A large number of heat transfer units are required;
3. Relatively high operating pressure is involved.
Coil heat exchangers are expensive because of the need for higher material costs and coil processing costs, as well as the cost of the central axis, the central axis of the heat transfer is of no use, but increased the diameter of the shell [5].
Glass Coil Heat Exchanger: The central axis of the heat exchanger is fused to the housing to prevent axial and shell lateral flow.
Body leakage [1 <]], the schematic diagram shown in Figure 3, for details see Chapter XIII.