Ch 5.2 - inorganic bulk acid - H2SO4

Question 1

How to go from S to H2SO4

Answer 1

S –oxi-> SO2 –oxi-> SO3 –abs + H2O –> H2SO4 (aq)

Question 2

What is the raw material for this process

Answer 2

S

Question 3

Process to collect S?

Answer 3

Frasch process (mining)

Question 4

Describe Frasch process

Answer 4

1. Super heated water in contact with S to heat it up: Solid –> liquid (low visc)
2. Compressed air pumps out low visc S liquid
3. S outlet, witll be solidifed

Question 5

What is roasting of ores

Answer 5

metallurgic process
gas –> solid reaction at ^T
purification metal component

Question 6

What is the most important process for S

Answer 6

Claus, uses off gas from refineries

Question 7

What are the 2 main parts of the Claus process

Answer 7

1. thermal, non-cat
2. cat

Question 8

What are the process conditions for the first part for Claus

Answer 8

exo, ^T (not bc of Chatelier, but bc it is a combustion reaction)

Question 9

What are the process conditions for the second part for Claus

Answer 9

catalyst
reheater in between, but decrease in total T
–> activation window of cat between 200-350°C

Question 10

what is the 2nd part loop of Claus

Answer 10

cool –> S out –> reheater –> reactor –> cool
x3

Question 11

What is the conversion after 3 beds? is it enough

Answer 11

95% conv to SO3, not enough

Question 12

What are the 3 big steps of the process

Answer 12

1. combustion of sulfur
2. Catalytic conversion
   3.absorption in water or weakly conc. H2SO4

Question 13

Describe the 1st step: combustion of sulfur

Answer 13

Dry air
liquid S = easier for transport
high T = low viscosity

Question 14

What are the 3 steps of the combustion of sulfur

Answer 14

1. dehydrating unit (H2SO4 +air)
2. Burner (S)
3. heat recuperation

Question 15

Why is it important to control the temperature in the combustion of S?

Answer 15

keep allotropic form
avoid solidification in pipes (130-155°C)

Question 16

What is the reaction of the 1st step, is it endo or exo?

Answer 16

S + O2 –> SO2
exo

Question 17

What is the 2nd step reaction, the catalytic conversion?

Answer 17

SO2 + 1/2 O2 –> SO3
exo

Question 18

What type of reactor for the catalytic conversion?

Answer 18

adiabatic packed beds with intermediate cooling (x4)

Question 19

What is the desired % of conversion / what is reached after step 2?

Answer 19

need: 99.7%
We have: 98-99%

Question 20

What is the norm on SOx?

Answer 20

2 kg SOx / t H2SO4

Question 21

Will playing with T and P help for the 3rd step? to boost the equilibrium

Answer 21

no

Question 22

What is the solution to obtain 99.7% conversion?

Answer 22

withdrawing the reaction product (SO3) through absorption = increases the curve

Question 23

What is the name of the modern sulfuric acid process

Answer 23

Souble absorption process

Question 24

What is the goal of a demister

Answer 24

avoid entrainment of H2SO4, mist/aerosols in piping

Question 25

Draw the process

Answer 25

to do

Question 26

Why is material choice important here?

Answer 26

corrosion issues

Question 27

Which material is favored?

Answer 27

Sandvick SX