The largest advantage of this machine is “first grind and second bake”,which is more energy-saving compared with “first bake and then grind”. It can grind large plaster stones into powders with diameter less than 0.2mm, zhich increases the specific surface when calcining, enlarfes the contact area with heat medium ,improve the calcination heat exchange efficiency and lowers energy consumption greatly.

 

Technique’s advantages:
 

1 first grind and second bake

  Compared with that of “first bake and second grind”, it is more energy-saving.

2 features of two other technipues:

  (1) first bake and second grind: due to the high energy comsumption, low production capability and uncontrollable ,unstable quality, it is a kind of backward technique at present, and is seldom adopted. Only a few factories are still applying it.

  (2) integration of “grind and bake”: this technique is good featured:low ehergy consumption, small investment, high efficiency, stable quality of the products and small area coverage. Besides, the dust volumn is concentrated and is envoromentally frindly. However, it is not mature at home and only BNBM ,one set of Peter-mill imported from German, runs into manufactures thistle board.

 

Operation mode of ebullience calciner:

   The bed state of gypsum ebullient calciner belongs to bubble bed, so this calciner is called “ebullience calciner ”. The calcining part of the ebullience calciner is a standing box-type container with a gas distribution board at the bottom for the purpose of protecting solid powder materials from leaking when the machine stops running, and sending the gas into lathe evenly from the bottom during the work. Continous feeding batch feeder is equipped above the upper bound of the bed. There are overflow holes on the furnace wall of the upper bound of the bed, which is used for discharging materials. Many heating pipes are equipped within the beds and the heating media whining the pipes are saturated steam or heat oil ; the heat is transferred through pipe walls to fluidiaed gypsum powder outside the pipe and makes the gypsum powder dehydrate and decompose. One electrical precipitator is eqipped on the upper calcination section ,and so the dust which is brought by gas when leaving fluidized bed shall be collected by the clectrical precipitator and returned to fluidized bed automatically. The dusted tail gas will be extracted by extract blower into the air. During normaol opetation, air will be blasted from the bottom of the ebullience calciner and then enter into fluidized bed through gas distribution board. Then the heat pipe flooded within the fluidized bed shall transfer a large amount of heat to materials and make the dehydrated gypsum powder reach the temperature of dehydration and decomposition. The dehydrated gypsum shall dehydrate crystal water and become steam. The steam mixes with the blasted air at the bottom of ebullience calciner and they move upward through bed. Since the steam is much more than air , the fluidization of the whole bubbling bed is realized by the steam. Due to ciolent tumbling and mixing of powder materials in the fluidized bed, the temperature and components of the materials at all positions of the whole fluidized bed are almost the same. The raw gypsum powder added continuously,once entering the bed, shall immediately mix with the hot powder materials within the bed evenly and quickly dehydrate and decompose in the hot powder. In order to avoid that raw gypsum extracting too early before finishing dehydration, the furnace is desighed to add a seperator to devide the fluidized bed onto a large and a small sections. The bottoms of two sections are connected. Raw gypsum enters into the larfe section firstly and dehydrates most of the crystal water; then comes to the small section through the lower part of the passage and completes the fimal dehydration and overflow the furnace fronm upper bed automatically.

 

Technical features of ebullience calciner:

1 the equipment is delicate and owns a large production capacity

2 structure is simple and hard to destroy

3 the equipment is compact and covers a small areas

4 low energy consumption