Green Chemistry and Engineering

CHE 432 Project Lignin waste stream to new products Spring 2018

Introduction:

Lignin is the support structure of many vascular plants. In wood, its composition is approximately 20-27% by dry weight. After processing wood for paper production, a lignin rich stream is dried and burned in the recovery boiler which creates steam for the paper process. The lignin rich stream is referred to as black liquor and contains hemicellulose and inorganic chemicals. Design a higher value product for the lignin waste. Design a process for separating the lignin waste stream and processing the lignin to create that product. Or, design a process to convert the hemicellulose and lignin into a new raw material stream for a different purpose.

Design Principles:

Design separations to remove any undesired species.

Consider processing technologies including reactions.

Consider the properties of the new product or raw material.

Consider profitability of the process with an estimated lifetime.

Background information:

Typical composition of waste black liquor stream: As high as 80% solids (bone dry material/(bone dry material + water). The age of the mill is a determining factor, as some older mills run at 65-70% solids. This includes a hemicellulose fraction, a lignin fraction, as well as inorganic chemicals.

After burning in the recovery boiler, the inorganic chemicals in the burned black liquor are recovered. This allows for eventual production of sodium hydroxide to be utilized back in the cooking process. (Sodium hydroxide and sodium sulfide are the cook chemicals for wood chips.)

A 2000 – 3500 ton (2000 pounds/ton)/day facility (finished bone dry paper) would have been fed 4000 – 7000 tons of bone dry wood chips/day. The ratio of hemicellulose/lignin probably varies, but you can use an average number or a common number for the Pacific Northwest.

Deliverables:

The entire term can be used for this project. The exact scope and deliverables will be negotiated with the project manager. A draft project timeline is due by April 10th.

Proposal: Proposed project scope with a timeline and deliverables. A literature review and information sourcing (you may want to make some phone calls) will be helpful for this deliverable.

Project Update: Preliminary process design, PFD, proposed product or raw material with flow rates and compositions of streams, update on timeline and future actions.

Final Project Report: Should include a process safety analysis, an economic analysis, and recommended path forward. Additional details will be based on what has been agreed up with the instructor as the term progresses, along with details provided through the course.

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