Activated Coke Desulfurization Process in Circulating Fluidized Bed Boilers: A Comprehensive Guide

Introduction

The activated coke desulfurization process is a critical technique in circulating fluidized bed (CFB) boilers, designed to reduce sulfur dioxide (SO2) emissions. Unlike traditional methods involving the circulation of clean coal, activated coke is introduced directly into the combustion gas stream. This process leverages the adsorption and catalytic properties of activated coke to achieve efficient desulfurization.

Understanding Activated Coke Desulfurization

A common misconception is that activated petroleum coke (APC) circulates within the fluidized bed itself. However, APC is added directly to the combustion gas as part of the flue gas recirculation (FGR) process. This method facilitates the capture of SO2 at temperatures below 150°C, which is significantly lower than conventional methods.

The Activated Coke Adsorption Process

The activated coke desulfurization process is a sophisticated method based on the principles of activated carbon adsorption. When SO2, O2, and H2O react in the presence of activated coke, they form sulfuric acid (H2SO4) which is adsorbed on the surface of the activated coke. This process effectively removes SO2 from the flue gas stream.

Saturated Adsorption and Desorption

After the activated coke becomes saturated with adsorbed H2SO4, it is directed to a desorption tower for heating and desorption. During this process, the H2SO4 decomposes back into SO2 gas, which is released with a concentration range of 20-50 ppm. The SO2 gas can then be processed further into valuable by-products.

Valuable By-Products

The SO2 gas from the desorption process can be converted into a variety of useful substances, depending on the desired end-product:

High Purity Sulfur: Straightforward conversion yields pure sulfur. Liquid Sulfuric Acid: By further processing, sulfuric acid can be concentrated to a liquid form. Sulfur Fertilizers: The SO2 can be utilized to produce fertilizers, ensuring sustainable agricultural practices.

Conclusion

Activated coke desulfurization in circulating fluidized bed boilers represents a forward-thinking approach to environmental protection and sustainable energy production. By leveraging the unique properties of activated coke, this process not only reduces harmful emissions but also provides valuable by-products. As industries continue to prioritize sustainable technologies, the activated coke desulfurization process is likely to play an increasingly significant role.

References

For those interested in implementing the activated coke desulfurization method, detailed guidance can be found in the following reference:

Implementing Activated Petroleum Coke for Desulfurization in CFB Boilers