From crude oil refineries to biorefineries – From existing to new business models using hybrid approaches

More than 20 key chemicals have emerged as basic components to lever from in these new portfolios, but not without specific challenges that are being addressed for complete understanding and viability.

Then, using established and commercially viable traditional sectors as a reference, differentiators can be identified to viably incorporate the biorefinery concept.

Production processes

Developing novel biorefineries is the key to unlocking production of these new commodities, and a mandatory comparison with well-established and fine-tuned petrochemical plants and traditional refineries is essential to fast tracking biorefinery consolidation as viable technological and business units, on top of the undeniable environmental and social benefits.

Linear programming modelling

Linear programming (LP) modelling is an analytical tool that has been used historically for most crude oil refineries and associated petrochemical plants to make economically optimal decisions about operations and commercial activities. Given a set of market conditions (crude and product prices and volumes) and processing capabilities (capacities and yields), LP modelling helps determine the best options for feedstock selection, processing and conversion units operation as well as products that can generate profitability.

This analytical tool has great applicability in biorefineries. LP models can provide insight into design to allow for unit configuration, define operating options and optimize biorefinery operations. As feedstocks are more complex in biorefineries, the multiplicity of processing options needs to be addressed systematically.

Processing units to build configurations in biorefineries

Processing units in biorefineries pose new design and operational challenges:

• Biorefineries, compared to refineries and petrochemical processes, need much more combined chemical and biotechnological processes. Therefore, integration represents a new challenge in the overall operation.
• Longer residence times are needed due to the nature of biochemical processes that need batch operations in a pseudo-steady state.
• Fairly mild operating conditions with high purities affect the selection of construction materials.
• The presence of oxygen can be used as part of the feed, instead of being detrimental to the processes.
• Relatively heterogeneous processes define wide ranges of processing envelopes when compared to more homogeneous processes for hydrocarbons.
• Product conversion represents a low yield due to the nature of biotechnological processes.
• Normally high water flow rates are required to treat feed and waste.

Feedstock, products and byproducts

Some characteristics of feedstock, products and byproducts found in biorefineries compared to traditional hydrocarbon processing plants:

• They are far more heterogeneous in terms of bulk components, e.g., carbohydrates, lignin, proteins and oils, among others. It is normally present in polymeric morphologies.
• The molecular weight of the product generally decreases with processing. The proper characterization and possible transformation of the feedstock needs a more accurate definition and functionality prescription.
• Feedstock generally has low sulfur content.
• There are not many metals present that are beneficial to the reaction processes.
• In terms of products, there are few so far, but they are increasing as technologies evolve (e.g., ethanol, furfural, biodiesel, mono-ethanol glycol, lactic acid and succinic acid, among others).
• Commercial scale feed rates demand much higher footprints and more unit operations to supply the processing units consistently.

From the Nelson complexity index (NCI) to the biorefinery complexity index (BCI)

In the petrochemical sector, complexity factors, such as the Nelson complexity index and others, are being applied positively to forecast the success of the operation, with an accent on the financial aspect. Based on the complexity of the operation, the ability to process feedstock into more or less complex products is weighted against the financial success of the investment. The biorefinery complexity index (BCI) is gradually being implemented as an analogy of the Nelson index. As the nature of the feedstocks used in biorefineries can inherently increase the complexity, maintaining an overall operable and viable facility will only be possible by having processing technologies in a commercial application state, meaning that implemented features have lower technical and economic risks, which in turn leads to successful business cases.

Summary

The biorefinery concept is aiming for a greater ability to process variable feedstocks and produce an increased diversity of products with variable specifications. As this concept grows and more processing blocks are defined and added, the complexity of these novel biorefineries need to be closely observed to maintain an overall controllable operation and financial success.

A hybrid model is a very attractive and somewhat logical approach. By integrating or incorporating biomass processing into petrochemical plants and refineries, upgraded to produce new goods through special retrofit projects, biorefineries can leapfrog into a consolidated future of more efficient production, and subsequently design, operation and maintenance challenges can be conquered more quickly.

Successful examples are green biodiesel, green hydrogren, pyrolytic lignin, green alcohols, which are fundamentally established and, in many cases, integrated into existing refineries. A number of well-known processing units are being transformed to process biomass or biomass intermediates. Integrated approaches in petrochemical plants and refineries can and are also being used for biomass feedstocks. New processing routes are also benefitting from utilities and additional chemicals available in established operations.

BBA is paving the way for several clients willing to take this leap toward the future.