CONTACT PROCESS $-$ SULPHURIC ACID PRODUCTION

Background

The largest producers and users of sulfuric acid are the fertilizer manufacturers and the mining industry where sulfuric acid is used for the reclaiming of uranium.

In South Africa, sulfuric acid is produced from three different raw materials:

S Sulphur,

Pyrite $(Fe{S}_2)$

$CaS{O}_4.$

All three of these processes involve the production of sulfur dioxide gas as an intermediate product.

With sulfur as raw material, sulfur is melted and burned in air to form $S{O}_2.$ This process gives a rich $S\frac{O_2}{?}$ gas mixture.

With pyrite, $S{O}_2$ is formed in a rotating oven or fluidized bed.

This process gives a more diluted $S{O}_2$ mixture.

The $CaS{O}_4-$ process gives a $S\frac{O_2}{?}$ air mixture that compares to that of the pyrite process.

The production of $S{O}_2$ is done in a rotating oven and requires a lot of energy.

The production process involves the oxidation of $S{O}_2$ to $S{O}_3$ via a vanadium pentoxide catalyst, with the addition of extra air for dilution and cooling.

In the next step the $S{O}_3$ is absorbed in concentrated sulfuric acid and reacted with water to form $H2SO4.$

Water is continually added to the $98-99\%$ absorption acid to prevent overconcentration and the forming of oleum $(H_2{S}_2{O}_7).$

The process can be divided into five stages:

$***$ Combining of sulfur and oxygen

& Purifying sulfur dioxide in the purification unit

& Adding excess oxygen to sulfur dioxide in the presence of catalyst vanadium pentoxide, with temperatures of $450C$ and pressure of $1-2$atm

Sulfur trioxide formed is added to sulfuric acid which gives rise to oleum $($disulfuric acid$)$

The oleum then is added to water to form sulfuric acid which is very concentrated.

Questions

Sketch the process flow diagram $($PFD$)$ for the contact process.

Label and name all process streams and process units, respectively.

Choose materials of construction for all streams and process units.

Justify your choice of material in reference to the following:Note:& Please use the internet to enlighten yourselves on the contact process $($YouTube videos and Articles$)$

Use the table format illustrated below when answering the questions.

& Your process streams and equipment numbering must be in line with your sketched PFD$.$

& Your justification $($question $4)$ must be detailed.

$\backslash$table$[[\backslash$table$[[$Stream$/$Equipment$],[$no$.]],\backslash$table$[[$Name of$],[$Stream$/$Equipment$]],\backslash$table$[[$Material of$],[$Construction$]],$Justification$],[1,$feed,Stainless steel,$],[2,$mixer,Stainless steel,$]]$