Sorbent Injection

CBEEC offers injection technology for introducing sorbents into the gas stream. This technology combines low capital cost together with low operating costs to deliver a reliable, cost effective method for reducing pollutants, such as acid gasses, mercury, and other heavy metals. This reliability comes from applying proven conveying technologies to the various sorbents that can be used for mitigating emissions.

CBEEC Dry Sorbent Technologies can be compatible with both Fabric Filters and Electrostatic Precipitator air pollution control technologies. The injection equipment requires a small footprint and can often be tied into the plant flue gas duct during a minimal shutdown, eliminating a significant disruption to plant operations.

CBEEC injection systems are designed to accommodate readily available sorbents. For SOX, and other acid gas emissions, trona or hydrated lime is typically used. For mercury control, the choice
would be powdered activated carbon (PAC), or brominated
powdered activated carbon (BPAC) for low chloride fuels.

SO2, SO3 and Other Acid gasses:

The sorbents of choice for these pollutants include Trona, a sodium-based product, and hydrated lime, a calcium-based product. Although trona is more reactive than hydrated lime (due to its sodium base), and therefore requiring less product for a given percentage removal, the optimal sorbent for a particular application will depend on additional factors including sorbent cost, transportation cost, equipment cost, and availability.

Trona and hydrated lime are usually delivered to site via PD truck or PD rail car and off loaded via pneumatic conveying to a storage silo. From the silo they are metered into a second pneumatic conveying system where they are transported over moderate distances to a suitable injection location within the flue gas duct. This conveying line, being of a relatively small diameter, can often be routed along existing structures which reduces both material and installation costs. The pipe diameter is a function of the amount of sorbent being carried, and the amount of conveying air used to transport the sorbent.

Removal efficiencies will vary according to the type of sorbent and the APC equipment downstream. A particulate control system incorporating a fabric filter can typically achieve higher removal efficiencies than an ESP. However, depending upon the sorbent and quantity, an ESP may still be sufficient to obtain a desired acid gas reduction and maintain the existing level of particulate emissions.

Mercury Reduction:

The current state of technology for mercury control is via the injection of activated carbon. The concept is that the mercury adsorbs onto the surface of the activated carbon. Depending upon the characteristics of the fuel, either a standard powdered activated carbon (PAC) or a brominated activated carbon (BPAC) can be injected into the flue gas stream to achieve a given reduction in mercury. Injection is typically after the air heater where gas temperatures are below 350^oF.

These sorbents are usually delivered to site via PD truck and off loaded via pneumatic conveying to a storage silo. From the silo, they are meter fed into a second pneumatic conveying system where they can be conveyed over moderate distances into the injection location. This conveying line, being of a relatively small diameter, can often be routed along existing structures which reduces both material and installation costs. The pipe diameter is a function of the amount of sorbent being carried, and the amount of conveying air used to transport the carbon.

Removal efficiencies will vary according to the type of APC equipment downstream . Usually, a baghouse system can achieve removal efficiencies in the 80 to 90% range whereas a system that features an ESP will be somewhat lower.