摘要
Acoustic signals emitted from particles and bubbles in the gas-solid fluidized bed were collected by the transducer located under the distributor and the result showed that the energy and deviation of acoustic signals varied regularly with superficial velocity.Superficial velocity was the minimum fluidizing velocity or the minimum turbulent velocity, while energy or deviation changed suddenly.Then a criterion to determine the change of flow pattern was obtained that when the ratio of acoustic energy or deviation reached the maximum, the velocity was the minimum fluidizing velocity, while the ratio of acoustic energy or deviation reached the next maximum the corresponding velocity was the minimum turbulent velocity.Experiments were carried out in a fluidized bed with inner diameter of 250 mm and polyethylene resin particles.The minimum fluidizing and minimum turbulent velocity obtained from the new method agreed well with those deducted from classical equations and traditional methods, including pressure difference method and pressure fluctuation method.In conclusion, an easy, sensitive, exact and on-line way to detect fluidizing velocity is presented, and this method is applicable to industrial equipment.
Acoustic signals emitted from particles and bubbles in the gas-solid fluidized bed were collected by the transducer located under the distributor and the result showed that the energy and deviation of acoustic signals varied regularly with superficial velocity. Superficial velocity was the minimum fluidizing velocity or the minimum turbulent velocity, while energy or deviation changed suddenly. Then a criterion to determine the change of flow pattern was obtained that when the ratio of acoustic energy or deviation reached the maximum, the velocity was the minimum fluidizing velocity, while the ratio of acoustic energy or deviation reached the next maximum the corresponding velocity was the minimum turbulent velocity. Experiments were carried out in a fluidized bed with inner diameter of 250 mm and polyethylene resin particles. The minimum fluidizing and minimum turbulent velocity obtained from the new method agreed well with those deducted from classical equations and traditional methods, including pressure difference method and pressure fluctuation method. In conclusion, an easy, sensitive, exact and on-line way to detect fluidizing velocity is presented, and this method is applicable to industrial equipment.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2008年第4期875-880,共6页
CIESC Journal
基金
国家自然科学基金重大项目(20490205)
国家高技术研究发展计划项目(G20070040)~~
关键词
声信号
气固流化床
起始流化速度
起始湍动速度
方差
acoustic emission signals
gas-solid fluidized bed
minimum fluidizing velocity
minimum turbulent velocity
deviation
