H-ACID MANUFACTURING

SUBJECT : CHEMICAL PROCESS INDUSTRIES-II

STUDENT NAME : SINDHAV JAYDRATH P.– 160283105011

LDCE

GTU

INTRODUCTION

H-Acid (l-amino-8-hydroxynaphthalene-3,6-disulfonic acid), an important dye intermediate, isproduced from naphthalene by a combination of the unit processes of sulfonation, nitration,reduction, hydrolysis and other processes. H Acid is used in the manufacture of a large number of azo dyes and pigments.

The Molecular Formula and Chemical are given :

FLOWSHEET

MANUFACTURING PROCESS:

• In the manufacturing process of H-Acid following Steps are involved:

• 1. Sulphonation

• 2. Nitration

• 3. Neutralization

• 4. Filtration & Washing

• 5. Reduction

• 6. Filtration & Washing

• 7. Concentration

• 8. Fusion

• 9. Isolation

• 10. Filtration

• 11. Drying

RAW MATERIAL & CHEMICALS

• Raw Manufacturing : Sulfuric acid,

Oleum,

Naphthalene.

• Chemicals : Nitric acid,

lime slurry,

Global Salt,

Iron powder,

Soda Ash,

Caustic Flex.

SULPHONATION

In this process, Naphthalene and H2SO4 is mixed in reactor for 1-2 hr and slowly heated up to 145-152 0C for 1 hr then it is cooled up to 85 0C by mixing H2SO4 and further cooled by passing water through jacket after adding water – for slow reaction rate, oleum is added within 10-12 hr and then mixture again heated up and cooled , and after 36 hr sulphomass passed to next step at 120 0C.

NITRATION

Nitration is highly exothermic reaction. Sulphomass comes into the Nitrator which will cool up to 95 0C, further its cooled up to 80 0C by adding 50 lit water. Then Nitric acid added gradually and mixed for 2 hr and temp will reached up to 40 0C. The whole process takes 15-16 hr for completation. Then nitro mass will goes to Neutralizer by applying air from bottom.

NEUTRALIZATION & FILTRATION AND WASHING

In the Neutralizer, Nitrosolution is taken from slurry tank. Then, global salt and Nitromass added gradually for 4-5 hr and then lime slurry added for 7-8 hr to bring pH up to 6. Mixture heat up to 80 0C, whole reactions takes 16 hr. This reaction produces gypsum as solid waste which is removed in filtration and filtrate from it goes to the Nitrosolution holding tank. Wash of hot water in nutsche is known as backwash of Nitro which is transferred to neutralizer. Filtration is 12-16 hr.

REDUCTION & FILTRATION AND WASHING

Nitro solution charged first with H2SO4 and large amount of Iron powder is added. The mixture is heated up to 90 0C for 3 hr. Then again Nitrosolution is charged with soda-ash to adjust pH up to 8-8.5. The reduced mass is sent to the filter press where Iron sludge is separated from Amino solution which is transferred to concentrator. Reduction will take 23 hr and filtration will take 12 hr.

CONCENTRATOR & FUSION

16% amino solution from filter press is concentration in open pan concentrator heating with steam at 100 0C for 16-17 hr and 40% amino solution which will go to the autoclave. The whole operation takes 22 hr. in autoclave caustic flakes are charged with amino solution and heated for 10-11 hr at 1820C and 80 psi. the fused mass is transferred to Isolation vessel.

ISOLATION & FILTRATION AND DRYING

Spent H2SO4 is mixed in fused mass in isolation vessel for 6-7 hr. due to acidic nature of reaction Na+ ions will be replaced by H+ at 90-92 0C and produces H-acid solution in which sodium sulphate particles are suspended, where SO2 will go to alkali scrubber. The slurry is taken nutsche filter. The Isolation will take 20 hr. H-acid is removed from top and the wash water from the filter will go to M.L.Tank. Filtration will take 16 hr. finally gray powder of H-acid of 60-65% obtained from Drier, which will go for storage and packing.

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