CMT can provide Soda Production Line EPC project, both solvay's ammonia soda process and combined ammonia process (Hou Debang).
Raw material: NaCl, NH3, CO2
Add the plenty of NH3 and CO2 into saturated salt water.
NaCl + NH3 + CO2 + H2O== NH4Cl + NaHCO3 ↓
And then calcine the NaHCO3 to obtain Na2CO3
2NaHCO3 == Na2CO3 + H2O + CO2↑
Brief process description of combined ammonia method (Hou Debang)
The soda production by combined ammonia method was founded in 1943 by Hou Debang (1890-1974), a Chinese chemical engineering expert.
It is a method that combines the two processes of ammonia alkali process and synthetic ammonia process to simultaneously produce two products: soda ash and ammonium chloride. The raw materials are salt, ammonia, and carbon dioxide --- the waste gas from the production of hydrogen from water and gas in synthetic ammonia plant. The chemical reaction principle is: C+H2O=CO+H2 CO+H2O=CO2+H2
The combined soda production method includes two processes: the first process is the same as the ammonia soda method, in which ammonia is introduced into saturated salt water to form ammonia brine, and then carbon dioxide is introduced to generate sodium bicarbonate precipitation. After filtration and washing, tiny crystals of NaHCO3 are obtained, and then calcined to produce a pure alkali product. The filtrate is a solution containing ammonium chloride and sodium chloride. The second process involves crystallization and precipitation of ammonium chloride crystals from a filtrate containing ammonium chloride and sodium chloride. "As the solubility of ammonium chloride at room temperature is greater than that of sodium chloride, the solubility at low temperatures is smaller than that of sodium chloride, and the solubility of ammonium chloride in a concentrated solution of sodium chloride is much smaller than that in water.". Therefore, under low temperature conditions, adding finely powdered sodium chloride to the filtrate and introducing ammonia gas can cause ammonium chloride to crystallize and precipitate separately. After filtration, washing, and drying, the ammonium chloride product is obtained. At this time, the filtrate obtained after ammonium chloride precipitation has been filtered out, and is basically saturated with sodium chloride, which can be recycled for use.
Compared with the ammonia alkali method, the biggest advantage of the combined alkali production method is that it improves the utilization rate of salt to over 96%, and uses the same amount of salt to produce more pure alkali than the ammonia alkali method. In addition, it comprehensively utilizes carbon dioxide from ammonia plants and chloride ions from alkali plant, while producing two valuable products - soda ash and ammonium chloride. Converting the waste gas carbon dioxide from the ammonia plant into the main raw material of the alkali plant to produce soda ash saves the huge lime kiln used to produce carbon dioxide in the alkali plant; Ammonium chloride, a nitrogen fertilizer, is produced by replacing the useless component chlorine ion (Cl -) from the alkali plant with the ammonia from the expensive sulfuric acid fixed ammonia plant. As a result, calcium chloride, which is not very useful and difficult to handle, is no longer generated, reducing environmental pollution, and greatly reducing the cost of soda ash and nitrogen fertilizer, fully reflecting the advantages of large-scale joint production.
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