Question $1$

You are tasked with performing both an order of magnitude $($Class $5)$ and study estimate $($Class $4)$ for the capital cost of a Maleic Anhydride production plant. A process flow diagram $($PFD$)$ and major plant item summary is appended to this brief.

The plant nominally produces $70,000$ tonnes per year of Maleic Anhydride, at a purity of $94\%($w$/$w$)$ using ethylbenzene as the feedstock. Byproducts generated include hydrogen, benzene and toluene. The plant is located on the US Gulf Coast and was constructed in the year $2020.$

As part of your estimates, you are required to:

Use a plant correlation to estimate the cost of a $70,000$ tpa Maleic Anhydride production plant and convert the cost to US$ $($in $2020)($Class $5$ estimate$).$

Use the reference cost correlations provided to estimate the purchase cost of each item of major equipment and convert the item cost to US$ $($in $2020).$ You are not required to account for installation factors, however, must consider the relevant material of construction for each item $($Class $4$ estimate$).$

You may use other correlations provided they are clearly presented and cited.

Using an appropriate Lang Factor, convert the total estimated equipment cost to an estimated plant cost in US$ $($year $2020)($Class $4$ estimate$).$

Costs of each item should be clearly summarised in a table, together with the total equipment cost. Material used in calculations must be clearly cited.

Sample calculations for the cost estimate of each item should be clearly presented in an appendix to the submission.

Any assumptions made should be clearly presented together with citations to any relevant material.

Process Description $($from Turton et al$.,2018)$

Currently, the preferred route to maleic anhydride manufacture in the US is via isobutene conversion in fluidized bed reactors. However, an alternate route via benzene may be carried out using a shell$-$and$-$tube reactor, with catalyst in the tubes and a cooling medium circulated through the shell. This configuration is shown in Figure $1$ below.

Benzene feed is vaporized in exchanger E$-601,$ mixed with compressed air, and then heated in a fired heated, $H-601,$ prior to being sent to a packed$-$bed catalytic$-$reactor, $R-601,$ where the following reactions take place:

All reactions are highly exothermic. For this reason, the ratio of air to benzene entering the reactor is kept very high. A typical reactor inlet $($Stream $6)$ concentration of approximately $1\mathrm{.}5$ vol$\%$ of benzene in air is used. Cooling is achieved by circulating molten salt concurrently through the shell of the reactor and across the tubes containing the catalyst and reactant gases. The molten salt is cooled in two external heat exchangers, E$-602$ and E$-607,$ prior to returning to the reactor.

The reactor effluent $($Stream $7)$ containing small amounts of unreacted benzene, maleic anhydride, quinone, and combustion products is cooled in exchanger $E-603$ and then sent to an absorber column, T$-601.$ In the absorber $($T$-601),$ vapour feed is contacted counter$-$currently with a recycled heavy organic solvent $($dibutyl phthalate$)$ via Stream $9.$ The solvent absorbs the maleic anhydride, quinone, and small amounts of water. Any water in the solvent leaving the base of the absorber $($T$-601)$ reacts with maleic anhydride to form maleic acid, which must be removed and purified from the maleic anhydride.

The bottoms product from the absorber $(T-601$ is sent to a separation tower $($T$-602)$ where the dibutyl phthalate solvent is recovered as the bottom product $($Stream $14)$ and recycled back to the absorber$.$ A small amount of fresh solvent $($Stream $10)$ is combined with the recovered solvent to account for minor losses. The overhead product $($Stream $13)$ from the separation tower $($T$-602)$ is sent for further purification via distillation where maleic anhydride is recovered at a purity of $99\mathrm{.}9$mol$\%.$ For simplicity, this final purification step has not been included in the process flow diagram of Figure $1$ or included in the stream table below $($ie$.$ Table $3).$

Table $1.$ Major Equipment Summary for the Maleic Anhydride Production Process $($shown in Figure $1$ below$).$

$\backslash$table$[[\backslash$table$[[$Compressor and Drives$],[$C$-601],[$Centrifugal$/$electric drive$],[$Carbon steel$],[$Discharge pressure $=250$kPa