In the acrylic production plant, the propylene is fed from a storage tank at a rate of $127$

kmo$\frac{l}{h}r$ and $10$ bar, which is mixed with compressed air is compressed as a source of

oxygen from atmospheric conditions, to $5$ bar. Steam is used to provide thermal ballast for

the exothermic heat of reaction, fed at $159C$ and $6$ bar at a rate of $993$kmo$\frac{l}{h}r.$ After

being mixed, the feeds $($propylene$,$ air and steam$)$ enter the reactor, where the oxidation

occurs at $310C$ and $3\mathrm{.}5$ bar. The reactor effluent proceeds to a separator where the

reaction is rapidly quenched to $40C,$ to avoid further oxidation. The off gas produced is

released, while the cooled outlet is then sent to two columns, where $99$ mole$\%$ acrylic

acids is produced of the final column.

Benzene

Propylene

Oxygen

Phenol

Acetone

The reactants are fed from their respective storage tanks. After being pumped up to the

required pressure $($dictated by catalyst operating conditions$),$ the reactants are mixed,

vaporized, and heated in the fired heater to the temperature required by the catalyst. The

shell$-$and$-$tube reactor converts the reactants to desired and undesired products as per the

above reactions. The exothermic heat of reaction is removed by producing high$-$pressure

steam from boiler feed water in the reactor. The stream leaving the reactor enters the

flash unit, which consists of a heat exchanger and a flash drum. The flash unit is used to

separate the $C3$ impurities, which are used as fuel for a furnace in another on$-$site

process. The liquid stream from the flash drum is sent to the first distillation column, which

separates benzene for recycle. The second distillation column purifies cumene from the $p-$

diisopropyl benzene impurity. Currently, the waste p$-$DIPB is used as fuel for a furnace.

The pressure of both distillation columns is determined by the pressure in the flash drum,

that is$,$ there are no pressure reduction valves downstream of the flash drum.

Based on the description of the acrylic production process above:

a$)$ Draw the PFD using appropriate symbols

b$)$ Name and label the unit and stream accordingly