First Limestone-Gypsum FGD Systems in Indian Market: Mitsubishi Hitachi Power Systems, Ltd.

- Uttar Pradesh, India

   There are multiple applications for removing sulfur and certain emissions from exhaust flue gases of coal-fired power plants. Some examples are: Wet scrubbing using a slurry of alkaline sorbents, spray-dry scrubbing, wet sulfuric acid process recovering sulfur in the form of commercial quality sulfuric acid; and dry sorbent injection systems.

National Thermal Power Corporation Limited (NTPC) is tackling the first series of limestone gypsum FGD systems in the Indian Market. NTPC is India's largest energy conglomerate with roots going back to 1975. NTPC Ltd is an Indian Public Sector undertaking, engaged in the business of generation of electricity and allied activities. Some of the largest coal fired power stations in India are owned and operated by NTPC.

Mitsubishi Hitachi Power Systems (Japan) has received an order from NTPC to implement India’s first ever Limestone-Gypsum FGD System in India. There will be six systems installed, on top of the already functioning power generating facilities in Central and Northern India. Two of the installation will occur at the Mouda Facility, with a combined capacity of 1320MW. Other systems will be installed at Rihand plants two and three, with 2000 MW capacity total. The FGD system type that will be implemented at these facilities will be a dry spray desulfurizing scrubber system.

Mitsubishi Hitachi Power Systems is a conglomerate of Mitsubishi Heavy Industries, Ltd. (MHI) and Hitachi, Ltd. Since 2014, MHPS has been achieving goals in environmental technologies and project engineering across the globe.

Here is how MHPS is helping NTPC curb emissions of atmospheric pollutants by using off-gas cleanup systems and technologies:

1.     The desulfurization absorbs sulfur oxides, and collects the generated gypsum by reacting limestone with SOx.

2.     The open sprayer system sprays absorbent (limestone slurry) from above the compact flue gas scrubbing tower to absorb harmful SOx efficiently.

More than ever before, India is pursuing rigorous emission-fighting methods for every stage of the energy producing process, from cleaning coal, to processing and utilisation technologies post combustion.  Since coal is still India’s top energy source, adding FGD type systems is actually becoming increasingly common. Only time will tell which technologies will aid India’s goals best and extend to industry wide practice.

Discussing Free CaO in CFB Ash and it’s Stability: Research Highlight from Coal Ash Asia 2017


- Beijing, China

Professor Qiao Xiu Chen from East China University of Science and Technology joined the discussion at Coal Ash Asia this past July 21-24 in Beijing, China. Prof Chen presented among industry leaders during the Fly Ash and Coal Gangue Track at the most recent AsianCAA event. The below abstract has been translated from its original submission to our proceedings.

Abstract: Circulating fluidized bed (CFB) boilers discharge 2 to 3 times as much ash per 1 kWh as pulverized coal-fired boilers. Overall, the amount of discarded CFB ash has drastically increased in China. However, there is no bulk utilization due to the different physiochemical properties of coal fly ash (CFA) from pulverized coal-fired boilers. One of the key issues is the amount of CaO left after burning, as CaO has negative effects on the soundness of cement. The national standard requires the maximum free CaO of 1% for F CFA and 4% for C CFA. The amount of lime in CFB ash is usually higher than 5% due to the desulfurization process. The utilization of CFB ash becomes harder when ash contains higher amounts of CaO. Presentation Abstracts

This conference we will show the chemical reaction variations of lime prepared at 800, 850, 900, 950, 1000, 1050, 1150, 1250, 1350°C. The calorimetry, precise measurement of lattice parameter and selected area microdiffraction of TEM were used for evaluation. The results showed that the calcite with a fineness of D100<76μm decomposed by 80% after the treatment at 800 or 850°C for 20 min. Complete decomposition occurred from the treatment at 900°C for 10 min. The maximum amount of CaO was 0.53% after the treatment at 1050°C. The amount of CaO started to be higher than 1% from the treatment at 1150°C and was more than 30% after the treatment at 1350°C for 20 min.

The CFB ash does not show a negative effect on the soundness of cement when the highest combustion temperature in the boiler is lower than 1050°C.

Sustainability Through CSA Cement

- Malaysia

Sustainability is simply the ability to meet the demands of today without negatively impacting the future. This goal is not easily met, especially in the construction industry. With demands for building materials on the rise in places like Malaysia and Vietnam, companies scramble to provide quality building materials such as concrete, cement, ceramic, etc, while still adhering to ever tightening restrictions on emission and waste disposal. Switching unfriendly environmental practices to a more efficient infrastructure of Building materials manufacturers providing suitable coal ash byproducts from local power station waste is not yet common practice. As legislative reform takes its time, researchers are attacking the problem of reusing industrial waste from all angles.

CSA (Calcium Sulfoaluminate) cement is another approach at reducing energy to produce environmentally friendlier cement.  Calcium Sulfoaluminate requires lower heating temperatures to produce. CSA is composed of a mixture of bauxite, limestone and gypsum and burning these at lower temperatures emits representatively lower amounts of carbon dioxide into the atmosphere. Also, the amount of limestone needed is much less. Limestone is said to be one of the key emitters of carbon dioxide in the sintering process. Using less materials and less energy is not only better for the environment, but more appealing to building materials manufacturers.

Dr. Tom Robl, Associate Director, Environmental & Coal Technologies at University of Kentucky’s Center for Applied Energy Research will be presenting the latest research and discussing CSA cement at the upcoming Coal Ash Asia. To join Tom at this year’s event please register by Clicking Here!