Operation control points of carbonization tower

Key points of carbonization tower operation control:

1. The production intensity of carbonation tower is an important indicator. It is generally expressed as the carbonization total volume utilization factor, whose unit (calculated as soda ash) is t / (m3.d), and the production intensity is multiplied by the volume of the tower.

的 The relationship between these three can be expressed by the following formula: W = BV where

W --- production capacity of tower (calculated by soda ash) t / d;

V --- the volume of the tower, m3

B --- production intensity of tower (calculated by soda ash) t / (m3.d)

Obviously, when the volume of the tower is constant, the capacity of the tower determines the strength of the production. The factors that affect the production intensity, in addition to the structural performance of the tower, also have operating conditions that affect the reaction and reaction speed, such as the concentration of reactants, temperature, gas pressure, the height of the liquid column in the tower, the cooling area of ​​the tower, and heat transfer. Efficiency, etc. Due to the limitation of the level of automation, these conditions in China currently rely on manual and DCS operating systems to control, master, adjust and utilize. Therefore, whether or not to increase the production intensity depends on whether the operators and management personnel can fully grasp the performance characteristics of the tower and properly control the use of all conditions to fully tap the potential of the equipment.

 The basic principles of operation control are:

First, we can not only consider the reaction rate regardless of the time required for the normal growth of the crystal nuclei, thereby reducing the crystal size, leading to deterioration of filtration and calcination conditions;

Secondly, it is not only necessary to speed up the production of alkali without regard to the necessary residence time of the carbonated ammonia brine, thereby reducing the conversion rate of NaCL and increasing the consumption of various materials and energy;

Thirdly, it is not possible to only show high-term or short-term production, regardless of the performance characteristics of the tower, which results in shortening the normal alkali production cycle, increasing the number of tower changes, and even causing disorder in the sequence of tower changes, resulting in unintended production fluctuations and losses. .

According to practical experience, the average production strength of carbonation towers expressed in terms of volume utilization coefficient is generally 1.0-1.2 soda ash / (m3.d) (including cleaning towers). The appropriate production strength indicators under various conditions should be determined. Based on specific exploration and data summarized in practice.

2. The concentration of NaCL and free ammonia in the ammonia brine entering the tower should be high, and the ratio of NH3 to CL- should be kept between 1.13 and 1.18.

越高 The higher the concentration of NaCL and free ammonia in the ammonia brine, the more complete the chemical reaction will be, and the more NaHCO3 will be generated, but NH3 and CL- should have a certain ratio, and the ratio of NH3 and CL- in the lye is 1 ﹕ 1. During the carbonization reaction, about 10%-13.5% of the ammonia in the ammonia brine is taken out by the tail gas exhausted from the top of the tower (the exhaust temperature at the top of the tower is low, and less NH3 is taken out; otherwise, it is taken out NH3 and more). Therefore, the ratio of NH3 to CL- in ammonia brine should be kept high. Ammonia brine contains free ammonia 99-103tt, containing CL-88-90tt, containing too low free ammonia will have a low NaCL conversion rate, and containing free ammonia too high will not only reduce the concentration of CL- and reduce the conversion of NH3, In addition, the phenomenon of "clogging tower" of the carbonated alkali-producing tower will occur, because a large amount of excess NH4 HCO3 will form crystals, which will block the inner wall of the tower, bacteria caps and cooling pipes.