Attention should be paid to the design and calculation of heat exchangers

1, shell wall thickness calculation
It includes the calculation of the wall thickness of the pipe case, the head and the shell
Tube and shell wall thickness shall meet the provisions of the minimum wall thickness of GB/T151, thickness is considered as corrosion allowance of C2=1mm for carbon steel and low alloy minimum wall, for the C2 is greater than 1mm, the minimum wall thickness of the shell should be increased accordingly.
2, the opening reinforcement calculation
The shell made of steel pipe, with integral reinforcement (increase of cylinder wall thickness or the use of thick walled tube); for tube box thick on the big hole considering economy, without a few strong points should meet the requirements:
Design pressure ≤ 2.5Mpa;
The center distance between the adjacent two holes shall be no less than two times of the diameter of the two holes
Take charge of nominal diameter ≤ 89mm;
The minimum wall thickness shall be taken as required (the corrosion allowance is 1mm)
3 flanges
When the standard flange is used, the flange should be matched with the gasket and the fastener, otherwise the flange shall be calculated. For example, gasket welded flange matching in the standard for nonmetallic gaskets; when the gasket flange to calculate response.
4, tube plate
Pay attention to the following problems:
Design of temperature of tube plate: according to the provisions of GB/T150 and GB/T151, should be not less than the temperature of metal elements, but in the calculation of tube plate can not guarantee the pipe, shell, metal temperature and tube plate is difficult to calculate, so the design temperature generally take the side of high temperature for the design of tube sheet (standard paraphrase)
Multi tube heat exchanger: the area that can not be supported by the heat exchanger due to the need of setting the baffle groove and the rod structure in the cloth distribution area, and is arranged in the equilateral triangle and square according to the GB/T151 formula
The effective thickness of tubesheet
The effective thickness of the tubesheet is defined as the thickness of the tube plate at the bottom of the bulkhead and the sum of the following two
A pipe corrosion allowance is beyond the depth of the pipe bulkhead groove
The maximum value of the corrosion margin between the B shell side and the tube plate in the shell side and the grooving depth of the two
5 、 expansion joint setting
In the fixed tube plate heat exchanger, due to temperature difference between the tube and the fluid in the tube side fluid, and the heat exchanger and the shell and tube version of fixed connection, so that the use of state, expansion difference between the shell and tube, shell and tube under axial load. In order to avoid the damage, exchanger instability, heat exchange tube pulled out from the tube plate, it should set the expansion joint, in order to reduce the axial load and shell heat exchanger
General in the shell and the heat exchanger wall temperature difference is bigger, need to set expansion joint consideration in tube sheet calculation, &delta calculation according to various temperature, &tau, total condition;; Q, one of them is unqualified, it is necessary to raise the expansion joint
δ — — heat transfer tube axial stress
τ — — shell cylinder axial stress
Q— — heat exchange tube and tube plate connection.