There are 16 platen superheaters, 12 platen reheaters and 8 wingwalls near the front wall and the rear wall of the furnace。 The cross-section of the furnace is 16。629 m (depth) ×16。617 m (width), the height of the furnace is

39。5 m。 The inner diameter of the cyclone is 8。3 m。 The convection pass is pided into two parts (front pass and back pass)。 Six roller ash coolers are set on the inside of the pantleg。 A tubular air preheater is equipped。

No。2 boiler: The general arrangement of this 300MWe CFB boiler is seen in Fig。 3。 It mainly includes pantleg furnace, four hot cyclone separators, a loop seal and a EHE under each cyclone separator。 Four EHEs are sym- metrically arranged on both sides of the lower part of the furnace, high temperature reheater(HTR) and low tem- perature superheater(LTS) are arranged in the two EHEs near the front of the furnace, they are mainly used for regulating reheated steam temperature and meanwhile effectingthe bedtemperature。Medium temperature su-

Fig。1Different arrangements of the heating surfaces in CFB boilers

Fig。 2General Arrangement of No。1 Boiler

Fig。 3General Arrangement of No。2 Boiler

perheaterⅠ(MTSⅠ)and medium temperature superhea- terⅡ(MTSⅡ)are arranged in the two EHEs nearthe back of furnace, which are mainly used for regulating the bed temperature and meanwhile taking into account the effect on bed reheated steam temperature。 Each EHE has an independent material feed inlet and an independent material return outlet。 High temperature circulation solids entering into the EHE under the regulation of the cone

valve conducts heat exchange with submerged tube heat- ing surface, and then returning cooled ash to the furnace, thereby regulating the bed temperature and steam tem- perature。

No。3 boiler: A commercial 300 MWe CFB boiler with single furnace, natural circulation and circulating fluid- ized bed combustion (Fig。 4)。 The boiler is composed of three main parts - a furnace with a waterwall membrane, three steam-cooled cyclone separators on the back of the furnace, a twin-exit loop seal at the end of each cyclone standpipe and the convection pass。 There are 12 platen superheaters, 6 platen reheaters and 2 wingwalls near the front wall and the rear wall of the furnace。 The cross- section of the furnace is 8。439 m (depth) ×28。275 m (width), the height of the furnace is 39。3 m。 The inner diameter of the cyclone is 8。5 m。 The convection pass is pided into two parts (front pass and back pass)。 Six roller ash coolers are set on the back of the furnace。 A tubular air preheater is equipped。

Fig。 4General Arrangement of No。3 Boiler

Steam-water circuits of the three boilers

No。1 boiler: Fig。5 shows steam-water system of No。1 boiler。 Feed water enters the in-line horizontal econo- mizertubeslocatedintheconvectionbackpass。The

drum receives pre-heated water from the economizer and feeds it to the evaporator。 The evaporative surfaces of the boiler consist of the combustor waterwall and wing wall in the furnace。 Drum internals separate and purify the saturated steam before it feeds the steam to the enclosure of the convection pass。 The steam is further heated in the

superheater stageⅠlocated above the economizer in the

back pass of convection pass。 After the first stage attem- perator the steam flows to the second stage platen super- heater in the furnace, it is pided into two parts: 8 pieces ofplatensuperheateraresecondsuperheaterI (SSⅠ),

which are arranged near the front wall of furnace, another

8 pieces of platen superheater are second superhea- terⅡ(SSⅡ), which are arranged near the rear wall of furnace。 The second attemperator is arranged between the

second stage superheater and the final superheater。 The final superheater is the first heating surface in the back pass of the convection pass。