Design Project, Phase 2

Due Tuesday, May 9

Memorandum

To: Badger Engineering process exploration teams

From: T. W. Root, Development Director

Re: Developing Glycerol Plant Design

As discussed in our meeting Thursday, April 27, we have determined to explore the acrolein/isopropanol route to glycerol in more detail. Process reaction conditions and specifications (obtained from a survey of literature and competitors’ processes) for key reaction steps are provided below. Notice also that the Research staff also has chosen to hydrogenate the acrolein to allyl alcohol before peroxide addition, rather than reducing the aldehyde after peroxide addition.

Feedback from the Marketing Department indicates that they do not anticipate selling excess glycerin from our initial, “world-scale” plant in the current supply/demand environment, so for this phase we will design a more moderate 10,000 metric ton/year plant to provide only for our own internal requirements. Our product will replace an external supply that arrives at 95% purity, so this is our product specification.

a) Please prepare an expanded flowsheet for the process showing all reactors and separations. Indicate stream flowrates, compositions, and temperatures where known or predicted.

b) Suggest realistic separations operations (distillation, extraction, etc.) where needed. Consider how the physical or chemical properties of the substances involved affect this choice.

c) Conduct energy balances on these key unit operations to estimate utility requirements (both heating and cooling).

d) Identify opportunities for heat recovery or integration. Our plant has steam available at several pressures, at the following internal costs. Will your process generate enough high-quality energy to recover significant value from selling steam from waste heat boilers back to the plant?

e) With your new Mass and Energy Balance information, obtain a more realistic Gross Profit for your process, and compare it to the corresponding value from your Phase 1 analysis.

Process reaction conditions and specifications:

Deutsche-Texaco process for isopropanol from propylene: react gaseous propylene with liquid water in a 12:1 molar ratio at 150°C and 100 atm over a strong acid ion exchanger catalyst. At a propylene conversion of 75%, the isopropanol selectivity is 94%, with 4% di-isopropyl ether and 2% heavy oligomers formed.

Hydrogen peroxide production: air is bubbled through a mixture of isopropanol and hydrogen peroxide at 5 atm and 120°C. The reaction mixture is diluted with water and fractionated to yield hydrogen peroxide solution, acetone, and unreacted isopropanol for recycle.

Shell acrolein process: gas-phase oxidation over Cu₂O/silicon carbide catalyst at 350°C with
2:1 air:propylene feed. Conversion of 10% gives acrolein selectivity of 85%, with the byproducts being equal amounts of acetaldehyde, acrylic and acetic acids.

Acrolein hydrogenation: 4:1 H₂:acrolein reacts at 300°C over a Pd catalyst with complete conversion and ideal selectivity.

Peroxide reactor: Allyl alcohol is mixed with aqueous hydrogen peroxide and a soluble
0.2wt% tungsten oxide catalyst at 60°C for 3 hours, producing 90% yield of glycerin in aqueous solution.

Final glycerol purification: use vacuum distillation if desired to reduce temperatures.

Utilities costs:

City water: $1.00/100 cubic feet

Cooling water: $0.25/100 cubic feet

Low pressure steam (3 atm): $3.8/10³ kg

High pressure steam (30 atm): $5.5/10³ kg

Physico-chemical property data:

Use data for T_bp, DH_vap, c_p, etc. from Felder & Rousseau,. Perry’s Handbook, and the CRC Handbook, or other sources you might locate in the library. When data is not available, estimates based on comparable compounds may be used, but be sure to note when you choose to use an estimate!