WTA technology for drying of lignite coal Jul27

WTA technology for drying of lignite coal...

WTA technology for drying of lignite coal WTA (Wirbelschicht Trocknung Anlage) technology for drying of lignite coal has been developed by German company RWE Power AG. WTA is the German abbreviation which stands for fluidized-bed drying with internal waste heat utilization. RWE Power AG holds a good number of patents on this technology. The first steam-fluidized bed dryer was developed by RWE as the WTA-1 demonstration plant at Frechen near Cologne, Germany,  with a throughput capacity of 53 tons per hour of raw lignite coal having a grain size of 0 mm to 6 mm and an evaporative capacity of 25 tons per hour. During the 20,000 hours of test operation from 1993 to 1999, the WTA-1 demonstration plant along with the vapour compression system for drier heating (employed for the first time worldwide in lignite coal applications) has proved to work extremely well and reliably. Further theoretical work and an evaluation of the test operation of the WTA-1 plant revealed further potential for the technical and economic process optimization. Several alternatives of development were considered and it was revealed that a reduction of the grain size held most potential for further improvement. In 1999, RWE built a test plant called WTA-2 for the fine grained WTA process directly next to the WTA-1 plant in Frechen. This new plant had a design capacity which was increased in several optimization steps from originally 16.4 tons per hour of raw lignite coal throughput and 8 tons per hour evaporation capacity to a raw coal throughput of 28.7 tons per hour and a water evaporation capacity of 13.1 tons per hour during the total of 8,200 hours of operation of the plant by 2011. Based on the extensive experience from the operation of the WTA-2 plant with...

Waste Heat Recovery Devices...

Waste Heat Recovery Devices  Industrial furnaces are used for carrying out certain processes which requires heat. Heat in the furnace is provided by (i) fuel energy, (ii) chemical energy, (iii) electrical energy or (iv) a combination of these energies. Gases which are generated during the process leaves the furnace at a temperature which is the inside temperature of the furnace and hence have a high sensible heat content. Sometimes the exhaust gases carries some chemical energy, which raises the temperature of exhaust gases further due to post combustion because of this chemical energy. The heat energy contained in the exhaust gases is the waste energy since it gets dumped in the environment. However, it is possible to recover some part of this energy if investments are made in waste heat recovery devices (WHRDs). Methods for waste heat recovery include (i) transferring heat between exhaust gases and combustion air for its preheating, (ii) transferring heat to the load entering furnaces, (iii) generation of steam and electrical power, or (iv) using waste heat with a heat pump for heating or cooling facilities. WHRDs work on the principle of heat exchange. During heat exchange the heat energy of the exhaust gases gets transferred to some other fluid medium. This exchange of heat reduces the temperature of the exhaust gases and simultaneously increases the temperature of the fluid medium. The heated fluid medium is either recycled back to the process or utilized in the production of some utilities such as steam or power etc. The benefits of WHRDs devices are multiple namely (i) economic, (ii) resource (fuel) saving, and (iii) environmental. The benefits of these devices include (i) saving of fuel, (ii) generation of electricity and mechanical work, (iii) reducing cooling needs, (iv) reducing capital investment costs in...