Project Description
Sodium nitrate (NaNO3) is a white, crystalline compound that is commonly used in various industrial and chemical processes. It is an important source of nitrate anion and sodium cation and finds numerous applications across different fields, such as machinery, metallurgy, fertilizers, glass, enamel, and fuel.
This project is an evaporation and crystallization unit, to concentrate and crystallize the sodium nitrate solution of around 10%, ultimately obtaining sodium nitrate solid products that meet all the performance indicators required by Party A.
Process Technology
According to the characteristics of feedstock sodium nitrate solution, a single-effect forced circulation process is adopted in this project, and the whole process flow is: a single-effect forced circulation for increasing the concentration of feedstock from 10% to over 60% which is oversaturated, then cooling crystallization for obtaining more crystals from the oversaturated liquor, then a centrifuge for separating solids from the mother liquor to get solid product.
The feedstock sodium nitrate solution of 10% was pumped into a condensate preheater and an exhaust preheater to be pre-heated before evaporation, and to take full advantage of talent heat of the condensate and the exhaust and reduce fresh steam consumption. After preheating, the material entered the forced circulation evaporator to be concentrated till oversaturated, and then the oversaturated liquor was delivered into cooling crystallization tanks to obtain more solids. And finally the mixture of solids and mother liquor enters a centrifuge to be solid-liquor separated, the filtered salts is transferred to the finished production warehouse, while the mother liquor is returning to the evaporator system to be concentrated again.
Equipment Description
One set of single-effect forced circulation evaporator was adopted, which is able to meet the following demands:
1). The sodium nitrate solution is concentrated till over-saturation;
2). Energy saving measures are considered to reduce the fresh steam consumption;
3). All components in the plant are well designed to ensure safety in production.
4). The forced circulation pump equipped can effectively prevent blocking risk of heat exchange tubes caused by high concentration of solid salts, and can slow the formation of scaling on the heat exchange surface at the mean time, improve the heat transfer efficiency, increase the continuous operation time of equipment, and reduce the cleaning frequency;
5). The main configuration of the system is as below:
a. One set of single-effect forced circulation evaporator, which consists of preheaters, heater, separator, condenser, forced circulation pump, vacuum unit and etc;
b. One set of centrifuge and mother liquor collecting and returning system;
c. One set of heat recovery system recovering condensate water;
d. One set of PLC control system.