1. Use aspen properties desktop

    2. Choose a base data bank that has similar solids to your requirement.

    3. Define it as a hypothetical solids

    4. Enter a name for it.

    5. Enter or calculate properties required by aspen properties to define the solid. This is the most frustrating part of the process as you may have seen

    6. Define the chemical structure if possible. Aspen properties can use to estimate property values at times

    7. If successful with all the above, the aspen propeties solver status will change from red to reflect minor errors which you may ignore.

    8. Export the property defination.

    9. Open Aspenplus or Hysys and choose the same databank as that for the hypothetical solid.

    10. Import the property defination and its ready for use in your simulation

VSPOLY general pure component solid molar volume model which is applicable to Salts and Conventional Inert Solids.

You can add to the simulation by:

• Going to the properties environment
• Selecting the Methods folder, Parameters folder and then Pure Components. 
• Add a T-dependent property, find solid molar volume and then select VSPOLY-1
• That will send you to an input screen where you choose your component (eg Lignin) and then input the coefficients in the correct order with the correct units. See the help for details (just search for VSPOLY).

You may need to tell Aspen to use this model by ensuring the parameter THRSWT/1 (first element of THRSWT) is 0.

Hope this helps. 

Mic

All the above are excellent approach to solve your problem. Just to mention, the V8.8 version has very good inbuilt parameters for cellulose and lignin compounds.