Waste heat pyrolysis plants* — which typically refer to systems that use lower-grade waste heat (e.g., from industrial exhaust gases, cement kilns, steel mills, or power plants) for indirect heating or integrate waste heat recovery — can encounter specific challenges with the carbon black byproduct (also called pyrolytic carbon black or recovered carbon black, rCB). These issues stem mainly from the lower and less uniform process temperatures compared to conventional direct-fired pyrolysis plants (which often reach 600–1000°C or higher with precise control). Key Carbon Black Problems in Waste Heat Pyrolysis Waste heat systems usually operate at lower effective pyrolysis temperatures (often 400 - 600°C, sometimes as low as 350–500°C) due to the limitations of available heat sources. This leads to incomplete devolatilization and secondary reactions, resulting in poorer-quality carbon black. The main problems include:

1. Higher Organic Contaminants and Residual Volatiles At lower temperatures, not all volatile organic compounds fully evaporate or crack away from the solid residue. This leaves bituminous substances, tars, or adsorbed hydrocarbons (up to 5–15 wt% volatiles) on the carbon black surface. Consequences: The material becomes sticky, agglomerates easily, has lower purity, and emits odors or VOCs during handling/storage. It also reduces reinforcing performance if reused in rubber.

2. Increased Polycyclic Aromatic Hydrocarbons (PAHs) and Toxic Impurities Incomplete pyrolysis promotes formation or retention of PAHs (e.g., up to 100–200 mg/kg in some low-temperature cases) and other toxic organics. Consequences: Health/environmental risks (PAH limits reuse in consumer products like tires or rubber goods; often requires additional detoxification (e.g., thermal post-treatment or solvent extraction).

3. Higher Ash Content and Inorganic Impurities Lower temperatures do not fully volatilize or react away inorganics (e.g., ZnO, SiO2, sulfur compounds from tire additives). Ash content can remain 15–25 wt% (vs. <10% in high-quality virgin carbon black). Consequences: Reduced surface area, poorer dispersion in polymers, and lower reinforcement properties (e.g., weaker tensile strength in rubber compounds).

4. Lower Surface Area and Poorer Structure Carbon black from low-temperature processes has BET surface areas often below 50–80 m²/g (compared to 80–120+ m²/g for virgin N330-grade used in tires). Particle agglomeration is common due to deposited pyrolytic carbon layers. Consequences: Inferior reinforcement in rubber (Payne effect: heat buildup and reduced elasticity), limited use as high-value filler; often only suitable as low-grade fuel or after expensive upgrading.

5. Agglomeration and Handling Issues Sticky residues cause clumping, making the carbon black hard to process (e.g., milling, pelletizing) and transport. High-temperature pyrolysis reduces this by burning off or cracking residues.

6. Inconsistent Quality Due to Heat Transfer Limitations Waste heat systems (e.g., indirect heating via heat exchangers or integration with flue gases) often have slower/uneven heating rates and poorer mass-heat transfer. Rotary kilns or moving beds using waste heat exacerbate this compared to direct-fired systems. Consequences: Batch-to-batch variability in carbon black properties, reducing market value. Lower efficiency and lower emissions often produces lower-value carbon black, requiring significant upgrading to be marketable beyond basic fuel uses. Conventional higher-temperature plants generally yield better carbon black quality. Designing or operating such a plant, focusing on heat integration and post treatment is key to viability.

Xpherion™CPS was created to address these challenges by solving environmental issues and creating value from a waste heat product. Our System Functionalizes the rCB (Carbon Black) into a Higher Grade Material making its value increase by 5X-40X.