The desulfurization agents and ammonia-free catalysts used in the desulfurization and denitrification processes are all based on calcium hydroxide (Ca(OH)₂) as the substrate, with manganese-based or manganese-copper-based materials serving as catalysts. They are processed into cylindrical pellets through mixing, stirring, extrusion, and drying steps.
A fixed-bed dry denitrification reactor can be installed (or ammonia-free denitrification agents can be directly filled into the existing fixed-bed desulfurization reactor), with no need for an additional dust removal system, as the fixed bed formed by the ammonia-free denitrification pellets inherently provides dust suppression and removal functions based on the principle of a granular filtration layer.
When calcium hydroxide reacts with nitrogen dioxide, it produces calcium nitrate (Ca(NO₃)₂) and water (H₂O).
The chemical reaction can be expressed as:
Ca(OH)₂ + 2NO₂ → Ca(NO₃)₂ + H₂O
This reaction is a typical acid-base neutralization reaction, in which calcium hydroxide acts as the base, and nitrogen dioxide (which forms nitric acid when dissolved in water) acts as the acid.
The entire process uses no water and produces no wastewater. The operation is simple and easy to control.
Based on the difference in flow direction between the flue gas and the downward movement of the solid granular material, fixed-bed integrated desulfurization and denitrification devices are classified into axial-flow and radial-flow types.
In an axial-flow fixed-bed dry denitrification system, the flue gas flows upward from the bottom to the top of the fixed-bed reactor, while the ammonia-free denitrification agent descends from the top under the force of gravity. The agent and flue gas come into countercurrent contact.
In a radial-flow fixed-bed dry denitrification system, the flue gas flows from the inner side to the outer side of the reactor, while the ammonia-free denitrification agent descends from the top under gravity. The agent and flue gas come into crossflow contact.
▲ Low initial investment;
▲ Low operating costs; The calcium-based fixed-bed dry method has relatively low overall resistance loss, resulting in low power consumption (electricity consumption) and no need for heating (ammonia-free denitrification requires low temperature increase), which reduces or eliminates the need for fuel media;
▲ Small footprint, especially suitable for sites with limited space or irregular areas;
▲ The calcium sulfate produced by the calcium-based fixed-bed dry method (desulfurization) is a solid waste that can be recycled by our company;
▲ The calcium nitrate produced by the calcium-based fixed-bed dry method (denitrification) is a solid waste that can be recycled by our company;
▲ The calcium-based fixed-bed dry method system requires almost no maintenance, does not need additional workers, and is easy and simple to repair and maintain;
What is even more noteworthy:
▲ The calcium-based fixed-bed can simultaneously achieve both desulfurization and denitrification functions. For projects that require phased construction, space can be reserved inside the tower for filling desulfurization or denitrification agents later. If desulfurization or denitrification functionality needs to be added in the future, there is no need for renovations, no shutdown, and no new equipment installation—simply add the desulfurization or denitrification agents online;
▲ All by-products of the calcium-based fixed-bed are solid waste, which is easier to handle compared to sodium salts from sodium bicarbonate desulfurization or the hazardous waste catalysts from SCR denitrification. Moreover, our company can take responsibility for recycling, relieving the client of future concerns.
▲ As a component of the calcium-based fixed-bed dry desulfurization and denitrification integration, ammonia-free denitrification completely eliminates the use of ammonia, addressing the complexities and risks associated with the transportation, storage, and delivery of ammonia water as a hazardous material;
