FGD (Limestone / Seawater)
INDURE has been successfully constructing ash handling systems in India and overseas with optimal use of precious and limited resources such as water and land. INDURE has immense experience and know-how having supplied ash handling systems for over 78,000 MW including systems for large units of 660 MW & 800 MW capacity. In addition, INDURE has successfully executed various turnkey contracts for medium size thermal power plants as well as EPC contracts for large Balance of Plant packages including units of more than 500 MW and complete power plants of various sizes. INDURE is well poised to undertake many Balance of Plant systems for large size plants and in line with the Government’s policy of “Make in India” INDURE has proactively entered into an alliance with Steinmuller Babcock Environment Gmbh of Germany to offer cost effective and state of the art pollution control technology to Clients in India.
INDURE has concluded an exclusive license agreement with Steinmuller Babcock Environment GmbH to provide proven solutions for meeting stringent SOx emission norms through state-of-the-art technology for lime / limestone based wet Flue Gas Desulphurization and also seawater based Flue Gas Desulphurization systems.
Steinmüller Babcock Environment GmbH is a leading name in the technology for flue gas cleaning and thermal waste treatment. Steinmuller Babcock Environment GmbH, headquartered in Germany has around 50,000 MW of Flue Gas Desulphurization installation base across the world. Steinmüller Babcock Environment GmbH has been developing solutions for environmental protection for over five decades and is an old company having roots which stretch back over 150 years.
Wet Limestone based Flue Gas Desulphurization System
The wet limestone gypsum process uses limestone as an absorbent for the desulphurization of flue gases and produces gypsum that is suitable for industrial use as an end product. The flue gases coming from boiler are directed into the absorber where the pollutants SO2, HCl, HF are removed before flue gas is released into the atmosphere through the stack.
In absorber, constructed as a spray tower, the flue gases are brought into contact with a suspension containing calcium, for removing pollutants from the gas. The absorber, has three main zones. In the lower part of the absorber, the sump, the scrubbing suspension is stirred, supplied with fresh absorbent and aerated. The stirring supports the dissolution of the absorbent, ensures even gypsum crystallisation and prevents the solids from settling.
To oxidize separated SO2 into sulphate (gypsum), air is blown into the absorber sump in front of the side entry agitators and thereby finely dispersed in the liquid. The flue gases enter the absorber above the sump and flow upwards through the contact zone. There are multiple levels of spray nozzles in the upper area of this zone which disperse the scrubbing suspension out of the absorber sump in the form of fine droplets. The mass transfer of SO2 from the flue gas into the scrubbing liquid takes place in this contact zone. In the absorber top, the flue gases pass the horizontally installed droplet separators which remove the liquid droplets from the gas. The cleaned gas has been cooled down to saturation temperature as it leaves the absorber.
Limestone is either delivered as a powder or it is ground in the plant with a wet ball mill and fed via a dosing station into the absorber sump. A part of the gypsum-containing suspension is removed from the scrubber and pumped to the gypsum dewatering, which preferably consists of a hydro-cyclone station and a belt filter. The gypsum is rinsed there and dewatered to a residual moisture of < 10% by weight. A small part of the cyclone overflow is discharged as wastewater in order to remove chloride, which is very soluble in water, from the absorber cycle.
Flue Gas Desulphurization System based on Seawater
Flue gas desulphurization systems based on seawater are a mature, cost-effective technology and an ideal solution for coastal locations. In this wet scrubbing process, seawater is used as the exclusive absorbent instead of the limestone typically used. The pollutant, Sulphur dioxide (SO2), dissolves in the seawater, forming sulphite and hydrogen sulphite. These compounds are neutralized by carbonates and bicarbonates, which are natural components of seawater. The air introduced into the oxidation basin oxidizes the Sulphur compounds into sulphate, which is a natural component of seawater too. The seawater used in this process is usually taken from the cooling water circulation of the power plant, and is directed back into the sea after its use as an absorbent in the seawater flue gas cleaning system.
FGD (Dry / Semi Dry)
Dry/Semi Dry Flue Gas Desulphurization System
Indure has immense experience and know how having supplied ash handling systems for over 78,000 MW including systems for large units of size 660 MW and 800 MW. Indure has further enhanced its portfolio for flue gas desulphurization systems by entering into an alliance with RAFAKO S.A, Poland to offer cost effective and advanced solutions for Dry/Semi Dry flue gas desulphurization systems to effectively control pollution from SOx emissions.
RAFAKO is one of the biggest Polish companies dealing with the design, manufacturing, construction and maintenance of machinery and power equipment. RAFAKO was establihed in year 1949 and is one of the key manufacturers from Europe for supercritical boilers, ESPs and FGD systems. RAFAKO has delivered more than 500 boilers all over the world including India with a total capacity of around 40,000 MW.
Semi dry/dry Flue Gas Desulphurization technology is cost effective especially for small to medium size power plant units and also very much suitable for projects with limited water availability.
The Semi-dry desulphurization technology being offered by Indure along with RAFAKO is based on the pneumatic reactor and the flue gas desulfurization process is usually carried out in two stages.
In the first stage, pulverized sorbent is injected into the area with temperatures which are optimal for calcination and bonding of SO2 in boiler furnace chamber. Later, in the second stage, flue gas desulfurization is further carried out in flue gas scrubber located between flue gas outlet from the boiler and electrostatic precipitator flue gas inlet.Within the scrubber, due to the spraying of flue gas with water, the particles of CaO covered with a layer of CaSO4 or CaSO3 develop cracks which enable the bonding of SO2 by CaO. The quantity of supplied water is adjusted so as to enable its complete evaporation. Temperature of flue gas upstream of electrostatic precipitator is reduced to the values which are safe from H2SO4 condensation point of view (below dew point).
The Semi dry process achieves better flue gas desulfurization efficiency as compared to Dry process in which sorbents (hydrated lime /quicklime/dolomite) are blown into the boiler furnace above the flame area.
Practically achievable flue gas desulfurization efficiency in Semi –Dry process amounts to 60%- 85% range, a level, which in case of power plants firing low combustible Sulphur coal – gives the possibility of meeting acceptable SO2 emission values. In addition the water consumption in the process is much lower as compared to wet limestone based flue gas desulphurization system.
Indure has rich experience and know how having supplied ash handling systems for over 78,000 MW including systems for large units of size 800 MW. In order to offer comprehensive solution for denitrification based on SCR (Selective Catalytic Reduction) technology, Indure along with its partner Termokimik Corporation, Italy is well positioned and equipped to offer state of the art SCR systems to clients in India.
Active since 1938, Termokimik Corporation is an engineering contracting and construction company from Italy specializing in the design, manufacturing, supply and installation of a wide range of processes and turn-key industrial plants in the field of environment control technologies. With more than 28,000 MW of successfully realized installations all over the world, Termokimik is a leading supplier of SCR systems to reduce emissions of Nitrogen Oxides.
Denitrification by SCR technology
A reduction in the amount of nitrogen oxides being discharged into the atmosphere as combustion gases are emitted from power and industrial plants has become an important goal to minimize environmental pollution. The most efficient secondary technique for removing such Nitrogen Oxides from the burning of fuels such as coal, oil and natural gas, municipal and hazardous waste, is their conversion into inert nitrogen gas by reaction with a reducing reagent, using the Selective Catalytic Reduction (SCR) technology through which reduction efficiencies of 90% and more can be achieved through SCR process which mainly consists of a reducing agent upstrem of one or more catalyst layers.
Catalysts may be produced in different configurations but for SCR DeNOx plants, honeycomb and plate-type catalysts are mainly used. Oxides of Vanadium, Titanium and Tungsten (V2O5, TiO2, and WO3) are widely used for ceramic monolith and composite SCR catalysts. Titanium oxides typically constitute the support while Vanadium is the active principle. Operating temperature ranges from 180 °C up to 500 °C, depending on several parameters like type of fuel, flue gascomposition and configuration of upstream flue gas treatment. The catalyst is installed inside a Reactor that can be positioned in different alternative places along the flue gas treatment line. Two configurations are most commonly used the “High Dust System“ upstream the flue gas treatment and the “Tail End System“ (which operates with cleaned gas). The best solution is obtained by taking into account process parameters, layout considerations and economical evaluations.