HARMFUL SUBSTANCE NEUTRALISATION SYSTEMS
Our company provides technologies enabling the neutralisation of harmful substances from flue gases with a significant reduction in investment outlays. This ensures compliance with emission standards taking into account the latest BAT conclusions set out in the MCP, LCP, and IED directives. Based on DSI (Dry Sorbent Injection) technology, an in-house product innovation was introduced in the form of ECOSERV FGTS. ECOSERV FGTS is an innovative system for flue gas treatment, particularly for the removal of chlorine and sulphur compounds based on the dry method for medium-sized grate boilers from 1 to 50 MW. The system is designed to run on dry sorbent dosed directly into the flue gas.
A combustion zone with a steam/water boiler, in which non-catalytic reduction of nitrogen oxides can be carried out in a temperature-appropriate combustion chamber area, followed by flue gas energy recovery.
Pre-dusting – it is not a necessary element; it only serves to improve the treatment process by reducing the water-insoluble dust fraction.
Sorbent injection – the sorbent is blown into the flue gas duct to neutralise acidic substances, such as HCl, SOx, and HF. In combination with activated carbon, this process also enables the adsorption of heavy metals, and organic micropollutants, including dioxins and furans.
Bag filter/ESP – captures reaction products and enables the further course of neutralisation reaction.
Emitter – the treated flue gas is finally directed to the stack, where appropriate measuring instruments measure its physical and chemical properties.
Flue gas treatment with sodium bicarbonate
Sodium bicarbonate NaHCO3
Other names: bicarbonate, baking soda
White crystalline powder:
- safe to use (food product)
- non-corrosive
- non-irritant
- non-toxic
- Before sodium bicarbonate is used in the flue gas treatment process, it must be ground to increase the specific surface area of the grains. This will result in increased effectiveness in reacting with acidic substances in the flue gas.
- The grinding process can be carried out directly at the plant just before injection into the flue gas duct using suitable grinders, or at its manufacturer by mixing it with substances that will prevent it from clumping during prolonged storage.
- The appropriately ground sorbent is introduced into the flue gas stream, where it is usually immediately decomposed at temperatures of 160 – 200 °C, known as thermal activation. Thermal activation also occurs at lower temperatures, already at about 60 °C, but very slowly. Above 140 °C, sorbent decomposition occurs immediately, and further temperature increases have no significant effect on the reaction kinetics.
Flue gas treatment with calcium hydroxide
Calcium hydroxide Ca(OH)2
Other names: hydrated lime, slaked lime
White or almost white powder:
- slightly soluble in water
- relatively cheap
- readily available
- an aqueous solution called lime water is a strong alkali (with a pH value of approx. 12) with a corrosive effect
- In dry flue gas treatment, calcium hydroxide with a well-developed specific surface area of the grains (>> 20 m2/g) is best suited; a special CaO slaking process obtains this structure.
- The best dry sorption results with Ca(OH)2 are obtained at flue gas temperatures below 140°C and above 300°C.
- The use of a bag filter and repeated recirculation of the sorbent has a positive effect on the sorbent reactivity.
- The fineness of the sorbent, its appropriate atomisation in the flue gas duct, and the humidity of the flue gas are also important factors influencing the acid neutralisation reaction with calcium hydroxide – the higher it is, the more efficiently the reactions take place.
BENEFITS
The benefits of a dry flue gas treatment process using dusty sorbents:
- maximises the energy efficiency of the system
- compatible with non-catalytic NOx reduction systems (SNCR DeNOx)
- particularly energy-efficient in a system with catalytic NOx reduction (SCR DeNOx)
- guarantees minimum maintenance intervals due to the simplicity of the system
- allows compliance with increasingly stringent emission standards
- minimises investment and operating costs
- a relatively simple system design
- simple, yet flexible system operation
- does not generate liquid process waste
- sodium bicarbonate-based sorbents are easy and safe to use, store etc.
- reaction products can be easily stored and transported
- no steam plume on the stack