High Temperature Odor-Free Recovery Boiler

Conventional recovery boilers employ direct contact between the black liquor and the flue gas in the flue in order to increase the concentration of the black liquor, resulting in sulfur compound and other unpleasant odors. With this the temperature of the generated steam was also limited to approximately 420°C because complete heat recovery was impossible due to the need to avoid internal corrosion by the flue gas. With the help of new a black-liquor concentration technology and employing various innovative designs and materials, a new boiler using concentrated black-liquor as fuel has been developed. With this boiler, concentrated black liquor preheating using steam and an indirect-type black liquor heater before being charged into the boiler. Because it is equipped with a superheater and economizer, the boiler generates steam with a temperature of 500°C and pressure of more than 100 kg/cm2, which is suitable for use in the paper mill or in electric power generation. While also resulting in dramatically improved thermal efficiency, this technology does not produce unpleasant smells as there is no direct contact between black liquor and the flue gases (NEDO, 2008. p.163).

Development Status Products

High Temperature Odor-Free Recovery BoilerCosts & Benefits

Parent Process: Chemical Recovery
Energy Savings Potential

With the new equipment, the boiler efficiency increases by 20%. For a boiler capacity of 150 t/hr and annual operating time of 24 h/day and 330 d/y, effective steam generation rate increases by 30 t/hr (NEDO, 2008. p. 164).

Indian flag In an Indian plant, with the installation of a high efficiency boiler, black liquor concentration was increased from 65% to 75% and resulting steam generation has increased from 2.6 t-steam/t-black liquor to 3.4 t-steam/t-black liquor (CII, 2008. p. 97).

CO2 Emission Reduction Potential

Equipment cost is estimated as ¥1,000 million. Construction costs are approximately ¥300 million. With an oil price of ¥1.81/4.14 MJ, the system has a pay-back time o f3.7 years (NEDO, 2008. p. 164).

Indian flag

 The installation cost of the high-efficiency bolier in the Indian plant (with 1100 tpd solids firing capacity) is estimated at Rs. 70 crores. The boiler is expected to generate Rs. 27 crores of additional revenue due to increased electricity production (CII, 2008. p. 97).

High Temperature Odor-Free Recovery BoilerSchematic

High Temperature Odor-Free Recovery Boiler Publications

Global Warming Countermeasures: Japanese Technologies for Energy Savings / GHG Emissions Reduction

This revised 2008 version of the publication from New Energy and Industrial Technology Development of Japan includes information on innovative Japanese technologies for energy efficiency and for the reduction of COemissions.  

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