Research And Improvement Of Steam Calcination Kiln For Sodium Bicarbonate With Inner Recycling Of Soda

Soda is an important fundamental chemical product. The sodium bicarbonate's calcination is one of the most important processes in soda production, in which the stream calcinations kiln is a key equipment. This paper aims at solving the technical problems in the stream calcinations kiln in Honghe Chemical Corporation Ltd. and presents a set of schemes.In order to increase the production capacity of the stream calcinations kiln, the paper analyses all sort of factors that affect the capacity and draws conclusion that heating area is one of the most important factors. Hence, the heating area is increased from 2670 m2 to 3307 m2 by adding a circle of tubes in the heating tubes, and the rotational speed of the kiln increases from 4.0rpm to 5.0rpm. Implementation of these two improvements increases the capacity of the calcinations kiln from 450t/d to 550t/d.To prevent the shut-down caused by the spoil of the tubes for non-condensed gases, it is proposed to remove all the tubes and connect them to the inner heating tubes. This measure improves the discharging manner of non-condensed gas, and prolongs the running period of the kiln from one month or so to above one year, raising the rate of production greatly.By taking the measures of increasing the amount of recycling soda, improving pre-mixture structure and using a sieving unit, it makes the amount of the grains lager than 2.0mm reduced from 11.85% to 2.55% and, therefore, improves the production quantity.In addition, the raw material balance and thermal energy balance are carried out based on the operation data in the kiln. It is found that the moisture contained in bicarbonate is the most important factor affecting the energy consumption. Thus this paper brings up the schemes of decreasing the moisture of bicarbonate and improving the soda filter. Also, the seal problem in the calcinations kiln is considered and improved.By adding four outlets for soda recycling, the numbers of times of recycling soda into the kiln increase from 16 times per minute to 32 times per minute, descending the ripple amplitude.At last, the paper presents the scheme for optimizing the operating parameters of the stream calcinations kiln of Honghe Chemical Corporation Ltd.