In this real-world case study, we will discuss the applicability of a pyrolysis oil centrifuge and its application for the large-scale production of bio-oil from used tires. The system described here is a Dolphin-built package around a remanufactured Alfa Laval MOPX 210 self-cleaning disc stack centrifuge.
Dolphin Centrifuge is the independent specialist in Alfa Laval centrifuges: remanufactured machines, turnkey systems, parts, and service, built on 40+ years of Alfa Laval experience and led by Sanjay Prabhu, M.S.M.E. Apart from Alfa Laval itself, Dolphin is the reliable source for quality Alfa Laval machines for pyrolysis oil duty, from the MOPX and WHPX disc stack separators to NX decanters, each one stripped, rebuilt, and tested in Dolphin's Warren, Michigan shop. Dolphin is an independent remanufacturer and is not affiliated with Alfa Laval.
Pyrolysis Process - Brief Description
Solid organic material (mostly petroleum-based), such as plastics, tires, etc., disintegrates into solid and liquid phases at elevated temperatures. This reaction occurs without oxygen and is generally referred to as pyrolysis.
Byproducts of Pyrolysis
Pyrolysis produces solids, liquids, and gases as byproducts. Charcoal, or biochar, is a solid by-product. Pyrolysis oil, aka bio-oil, is a liquid by-product.
Bio-oil is of primary interest due to its properties being like those of petroleum. Further refining of bio-oil yields fuels like diesel and fuel oil. These work well as replacements for commercial fuels, i.e., diesel fuel and fuel oil in engines.
Separating Challenges in Pyrolysis Production
The large-scale production of bio-oil through the pyrolysis process has its own challenges. Separation of the 'char' or solid residue left over from the reaction is one of them.
The nature of these particles makes them difficult to separate using conventional filters. Conventional filters plug up fast from the fine particles, which are also sticky.
Bio-oil produced by pyrolysis of tires has metal particles from the steel wire mesh in tires. If not removed, this can cause considerable damage to downstream equipment.
Industrial Centrifuges - Processing Solution
Industrial centrifuges are heavy-duty separating machines. They are mechanical separators designed to separate liquids from solids continuously.
Two types of centrifuges apply to pyrolysis oil separation.
First, decanter centrifuges are suitable for crude pyrolysis oil de-sludging. A high-speed, disc stack centrifuge polishes the de-sludged bio-oil from the decanter. Summarized below are the technical capabilities of each type of centrifuge. Dolphin remanufactures and supplies both types as Alfa Laval machines: NX series decanters for the coarse cut and MOPX or WHPX self-cleaning disc stack separators for the polish.
Types and Capabilities
Decanter Centrifuge
- Max. % Solids: Up to 50% (v/v)
- Max. Solid Particle Size: 1/2"
- Min. Particle Size Separated: 50 µm
- Capacity: ~10 GPM to over 350 GPM
- Processing Mode: Continuous (Not batch)
Self Cleaning, Disc Stack Centrifuge
- Max. % Solids: Up to 5% (v/v)
- Max. Solid Particle Size: 250 µm
- Min. Particle Size Separated: 0.5 µm
- Capacity: ~2 GPM to over 100 GPM
- Processing Mode: Continuous (Not batch)
Applicability to Pyrolysis Oil Production
Industrial centrifuges are perfect for this application in 2 ways.
Separation of crude pyrolysis oil from coarse sludge:
A decanter centrifuge (as detailed above) is ideal for separating crude pyrolysis oil. It separates the bulk sludge, including char and large metal particles, in a continuous process.
Removal of fine remaining solids (from step 1):
A pyrolysis oil centrifuge (self-cleaning, disc-stack type) removes the finer solids from the bio-oil. This, again, is a continuous process that produces clean pyrolysis oil.
Real World Application of Industrial Centrifuges for Pyrolysis Production.
Dolphin Centrifuge built the system shown here around a remanufactured Alfa Laval self-cleaning disc stack centrifuge. The skid, heat exchanger, feed controls, and panel are Dolphin's engineering; the separator inside is Alfa Laval. This system was for a pyrolysis oil producer on the west coast.
The customer supplied the oil from the post-straining tank. A heat exchanger reduced the temperature before entering the centrifuge system. The 'self-cleaning' centrifuge separated all fine metal and char particles. The result was clear bio oil ready for sale!
Centrifuge Specifications
Remanufactured Alfa Laval MOPX 210 centrifuge for the pyrolysis tire oil processing system, including:
- Alfa Laval MOPX 210 Self-Cleaning Disc Centrifuge
- VFD Control for customer's PD Feed Pump
- Fully Automatic PLC/Touch-Screen Control Panel
Technical specifications of this pyrolysis industrial centrifuge: 3-Phase separation of pyrolysis oil to remove fine sediment down to 0.5µ. The system processes up to 30 GPM of pyrolysis oil at 200 F to separate all metal and organic sediment.
Summary
Pyrolysis oil production on an industrial scale needs mechanical separation. An industrial centrifuge is ideal for separating char and other debris from pyrolysis oil continuously. The centrifuge produces clean pyrolysis oil with less than 0.1% sludge.
by Sanjay Prabhu MSME
Engineering Manager, Dolphin Centrifuge