Flooding rectification

Excessive feed preheat. Flooding of rectification section packed bed. Operational error. 

Feed Temperature A hotter feed can increase feed vaporization and thus reduce reboiling duty. However, higher temperature feed could cause too much vapor resulting in rectification section flooding. For an existing tower, the optimal feed temperature corresponds to the lowest reboiling duty, while the tower can meet product specifications. 

The SBD model is based on the assumption that droplet formation occurs at the flooding point and therefore describes the flooding point mechanism accurately, both for higher and smaller gas velocities in pressure absorption and rectification processes, see Fig. 2-17a, 2-17b, 2-17c, 2-17d and 2-17e... 

Based on the dimensionless Eq. (2-73) and/or (2-69), it is possible to determine the gas and/or vapour velocity with a mean relative error of 6% for systems used in vacuum and normal pressure rectification as well as in absorption processes, if the physical properties pl, ov) hL) hv l the geometric packing data a and < and the hquid hold-up at the flooding point h p are known. In the case of pressure systems, the gas velocity at the flooding point can be determined with an accuracy of 15%, see Fig. 2-17e. 

Table 4-4d. Determination of pressure drop in irrigated packed column in counter-current flow acc. to Eq. (4-48) or (4-50) and (4-54) throughout the entire operating range up to flooding point. List of test points and relative mean errors <5 (Ap/H) for tested structured packing, valid for system rectification systems acc. to Table 2-2... 

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