Mitsubishi Heavy Industries Limited

Mitsubishi Jukogyo Kabushiki Kaisha

Yoshihisa Arakawa

Hirokazu Hino

Yasuhiro Yamauchi

Toshimitsu Ichinose

Kimishiro Tokuda

Masaaki Nagai

Kenichi Arima

Masakazu Tateishi

Kenji Tagashira

Kikuo Tokunaga

Yukihisa Fujima

Takayuki Maeda

Kazuyuki Myoyo

Isao Torii

Yoshitaka Baba

Kiyomasa Takenaga

Michimasa Yagi

A boiler recovers a soda component from pulp spent liquor and is able to prevent carry-over of unburnt char and deformation of a char bed configuration and to attain a stable combustion with low NO,generation. By regulating the combustion air supply, and feeding inert gas along a furnace side wall around the char bed, there are formed a combustion zone of reduction atmospheric field where air ratio in the surroundings of the char bed is 0.8 or less, a combustion zone of reduction atmospheric field where air ratio is 1.0 or less and unburnt components exist (including the case of a reduction atmospheric field where air ratio is 1.0 or less and unburnt components exist with the two combustion zones being combined together) and a combustion zone where combustion is completed.

Recovery boiler

A particle movement controller, being disposed between a first fluidized bed, to where particles are supplied, and a second fluidized bed, from where particles are discharged, which controls the moving amount of the particles from the first fluidized bed to the second fluidized bed, is improved to have a substantially proportional characteristic without a hysteresis. Flow rate control nozzle pipes 30a, 30b, . . . , 30j made of horizontal pipes are disposed vertically at intervals and nozzle holes 31 are formed in a lower surface of each of the nozzles. An amount of air emitted from each nozzle hole 31 is controlled using opening and closing valves 33a, 33b, . . . , 33j or flow rate adjustment valves 35a, 35b, . . . , 35j (FIG. 2).

Particle movement amount controller for fluidized beds

This invention relates to a process for removing sodium chloride and potassium salts, which are impurities concentrated and accumulated in pulp digesting chemicals, from ash collected from a soda recovery boiler. This process comprises the steps of (a) mixing ash collected from the combustion exhaust gas of the soda recovery boiler with water to form a slurry, adjusting the pH of the slurry to 10 or less by the addition of sulfuric acid, adjusting the temperature of the slurry to 20.degree. C. or above, and holding the slurry at that temperature for a sufficient time to cause sodium chloride and potassium salts present in the collected ash to be dissolved in the water; (b) cooling the slurry to a temperature below 20.degree. C. by the addition of ice and/or water so as to precipitate solid matter therefrom; and (c) separating the slurry into solid and liquid components and recovering the solid component while discharging the liquid component out of the system.

Process for removing sodium chloride and potassium salts from ash

The known method of burning solid fuel by means of a fluidized bed is improved so as to reduce the amount of generated NO.sub.x and to enhance the efficiency of combustion. Primary air, secondary air and tertiary air are respectively fed through a primary air feed port opening at the fluidized bed, through a secondary air feed port opening at a free board downstream of the fluidized bed and through a tertiary air feed port opening downstream of the secondary air feed port. The feed rates of the primary air, secondary air and tertiary air are respectively controlled so that the air ratios with respect to the theoretical amount of air after charging of the primary air, after charging of the secondary air and after charging of the tertiary air may become about 0.6-0.8, about 0.8-1.0 and about 1.0 or higher, respectively. Preferably, unburnt ash sputtered from the fluidized bed is recirculated into the fluidized bed.

Method of burning solid fuel by means of a fluidized bed

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Tokyo, Japan

Yoshihisa Arakawa