Sodium carbonate is produced by Solvay method, and the principle of Solvay s alkali production metho

NH4HCO3+NACl=NH4Cl+NAHC3 If CO2 is passed first, because the solubility of CO2 is small, the amount of dissolved CO2 is limited, and even if more NH3 is introduced later, it cannot provide enough HCO3- to precipitate sodium carbonate solids. Therefore, the order of NH3 first and CO2 cannot be reversed.

According to the above reaction, it can be seen that the main component of the mother liquor is ammonium chloride, and the reaction of adding quicklime:

-2NH4Cl + CAO=2NH3 (gas) + CaCl2 + H2O Hou's alkali method:

-There is no need to use quicklime, which reduces production costs.

-No impurity ions are introduced into the mother liquor, and calcium ions can be recycled.

- The resulting by-product, ammonium chloride, can be used as a chemical fertilizer.

NH4HCO3+NACl=NH4Cl+NAHC3 If CO2 is passed first, because the solubility of CO2 is small, the amount of dissolved CO2 is limited, and even if more NH3 is introduced later, it cannot provide enough HCO3- to precipitate sodium carbonate solids. Therefore, the order of NH3 first and CO2 cannot be reversed.

According to the above reaction, it can be seen that the main component of the mother liquor is ammonium chloride, and the reaction of adding quicklime:

-2NH4Cl + CAO=2NH3 (gas) + CaCl2 + H2O Hou's alkali method:

-There is no need to use quicklime, which reduces production costs.

-No impurity ions are introduced into the mother liquor, and calcium ions can be recycled.

- The resulting by-product, ammonium chloride, can be used as a chemical fertilizer.

The college entrance examination has been more than a year in the past year, and last year's several bureaus were very clear, and this year I had to check the book == detailed flow chart.

I've attached it, if you don't understand any of the processes, you can ask me in detail.

Solvay's alkali method.

That is, the ammonia-alkali method.

Pros:1As can be seen from the figure, the theoretical NH3 is fully recycled, that is, there is no need to supplement NH3 in the production process (there is actually a small amount of loss).

At the same time, it also achieves the complete utilization of CO3 2- in limestone (CO2 recycling, putting into reproduction, theoretical conversion rate.

2.Raw salt is cheaper than limestone.

3.The process is simple.

Disadvantages: The utilization rate of raw materials is not high, and finally a large amount of salt is mixed with the low-value CaCl2 waste liquid and is ground by the waste potatoes, and Ca2+Cl- is not utilized.

Hou's alkali method is also the alkali method.

Pros:1The by-product is NH4Cl with high utilization value

2.The utilization rate of salt is high, and Na+ and Cl- are used in the filling shirt

**For the exhaust gas of ammonia synthesis, the two industrial processes are combined to achieve environmental protection and full utilization to the greatest extent.

A sufficient amount of ammonia gas is introduced into the saturated brine to saturation, and then CO2 (obtained by calcination of CaCO3) is introduced under pressure

NH3+CO2+H2O===NH4HCO3NaCl+NH4HCO3===NAHCO3 +NH4Cl calcins or Kai the precipitated NaHCO3 crystals to obtain Na2CO3:

2nahco3

na2co3＋co2↑＋h2o

NH4Cl in the mother liquor plus slaked lime can be **ammonia, so that it can be recycled:

2nh4cl＋ca(oh)2

cacl2+2nh3↑＋2h2o

The advantages of this method: the raw materials are economical, can be continuously produced, and the rock group cherry CO2 and NH3 can be used.

Disadvantages: A large amount of CaCl2 is of little use, the utilization rate of NaCl is only 70, and about 30% of NaCl remains in the mother liquor.

Principle:

NaCl+NH+CO+HO===NaHCO+NHCl,CaCo=High Temperature=CaO+Co,CaO+HO=Ca(OH),2NHCl+Ca(OH)=2NH+CaCl+2HO

2NaHCO = high temperature = Na Co + Co H pre-code O, the CO and NH generated by the reaction can be reused as raw materials.

The total reaction formula is: CaCo +2NaCl = High Temperature = CaCl + Na Co (Note: Not a metathesis reaction.

Later Hou Debang.

The method was changed and coarse, that is, the Hou's alkali method.

Disadvantages: Solvay's alkali method.

The main disadvantage is that half of the raw materials are not used, and only sodium in salt and carbonate in lime are used.

The combination of the two is the formation of soda ash. The other half of the chlorine in the table salt and the calcium in the lime combine to form calcium chloride.

None of this product was used.

Ammonia-alkali method. The production has realized the continuous production, the utilization rate of salt has been improved, and the product quality is pure, so it is called soda ash, but the biggest advantage is low cost.

The flow chart of Solvay's alkali production process is as follows:

Solvay's alkali production method is a process that uses sodium chloride as raw material to prepare alkali by hydrothermal method, also known as sodium chloride hydrothermal method. NaCl + NH + Co + H O = = = NaHC + NH Cl, Caco = High Temperature = Cao + Co.

CaO+H O=Ca(OH), 2NHCl+Ca(OH)=2NH+CaCl+2H High Temperature=Na Co+Co HO, the CO and NH generated by the reaction can be reused as raw materials.

The total reaction formula is: CaCo +2NaCl=High Temperature=CaCl +Na Co (Note: It is not a metathesis reaction) Later, Hou Debang improved the method, that is, Hou's alkali method.

Cons:

The main disadvantage of Solvay's alkali production method is that half of the raw materials are not used, and only sodium in table salt and carbonate in lime are used, and the two are combined to produce soda ash. The other half of the chlorine in the salt is combined with the calcium in the lime to form calcium chloride, and this product is not used.

The ammonia-alkali method enables the production to achieve continuous production, the utilization rate of salt is improved, and the product quality is pure, so it is called soda ash, but the biggest advantage is that the cost is low.

The reaction steps are:

NaCl+NH3+CO2+H2O===NaHCO3+NH4Cl, CaCO3=High Temperature=CaO+CO2, 2NH4Cl+CaO====2NH3 +CaCl2+H2O

2NaHCO3 = high temperature = Na2CO3 + CO2 + H2O The CO2 and NH3 generated by the reaction can be reused as raw materials.

The total reaction formula is: CaCO3 + 2NaCl + H2O + CO2 = high temperature = CaCl2 + 2NaHCO3

Later, Hou Debang improved the method, that is, the Hou's alkali method.

A sufficient amount of ammonia is introduced into the saturated brine to saturation, and then CO2 (obtained by calcination of CaCO3) is introduced under pressure, because the solubility of NaHCO3 is small, so the following reactions occur:

NH3+CO2+H2O===NH4HCO3NaCl+NH4HCO3===NAHCO3 +NH4Cl calcinate the precipitated NaHCO3 crystals to obtain Na2CO3:

2NaHCO3 NA2CO3 CO2 Doupai NH4Cl in H2O mother liquor plus slaked lime can be **ammonia for recycling:

2NH4Cl Ca(OH)2 CaCl2+2NH3 2H2O Advantages of this method: economical raw materials, continuous production, CO2 and NH3 can be used for dust sales.

Disadvantages: A large amount of CaCl2 is of little use, the utilization rate of NaCl is only 70, and about 30% of NaCl is left in the mother liquor pie shed.

1. In addition to the synthesis of soda ash, the ammonia used in the combined alkali production method will also be used to synthesize ammonium chloride, unlike the Solvay alkali method, which will cause a certain waste of raw materials.

2. The purity of soda ash obtained by the joint method is slightly lower because it recycles the saturated salt water of **, which often contains a certain amount of ammonium chloride, which will precipitate together when baking soda is precipitated, thereby slightly reducing the purity of baking soda, but as long as it is purified again, it can get high purity.

3. There is nothing short of the combined alkali production method.