A techno-economic study on the co-production of syngas and activated carbon from waste tyre gasification process

Waste tyre gasification offers a variety of benefits amongst which include the production of syngas—an alternate source of energy generation and activated carbon (AC)—a very good adsorbent used in industrial purification processes. In this study, a conceptual design of an industrial production plant design process and economic analysis of waste tyre gasification process for the co-production of syngas and AC were evaluated. Three reactor configurations namely: fluidized bed, fixed bed, and rotary kiln gasifiers were investigated in the design process. The design process put into consideration the total plant cost (TPC), total capital investment (TCI), the cost of raw materials, waste disposal cost, amongst other vital economic parameters. The fixed bed reactor has the highest syngas and AC production with 10,130 kg/h and 214.61 kg/h, respectively when compared to the other gasifiers. The minimum selling price (MSP) of syngas was set as 1$/kg and AC was set at $2/kg. The result obtained shows that the fixed bed production route was the most economical amongst the three reactor configurations considered. The fixed bed route has a net present value (NPV) of 435 M$, return on investment (ROI) of 56%, internal rate of return (IRR) of 54%, and a payback period (PBP) of 4.86 years. Finally, a sensitivity analysis considering a ± 20% variation in key economic parameters such as the syngas MSP, inflation rate, interest rate, tax rate, operating expenditure (OPEX), and capital expenditure (CAPEX) amongst others was investigated. The analysis shows that the syngas MSP, OPEX, inflation rate, and CAPEX have the most effect on the NPV of the waste tyre gasification process.