A method for determining the heat transfer coefficient of bubbles in a polyethylene fluidized bed
A technology of polyethylene fluidized bed and heat transfer coefficient, which is applied in the direction of material analysis, instrumentation, and analysis of materials using acoustic wave emission technology, which can solve problems such as poor accuracy and dispersion of unsteady test results, and achieve accurate bubble heat transfer Coefficient, the effect of high detection accuracy
Active Publication Date: 2017-12-29
ZHEJIANG UNIV
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However, the unsteady-state experimental results are extremely scattered, and its accuracy is worse than that of the steady-state heat transfer method.
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[0020] The measuring method of bubble heat transfer coefficient of polyethylene fluidized bed comprises the following steps:
[0021] Step 1: Acquisition of acoustic emission signals. The installation height of the acoustic emission signal receiving probe has little effect on the main frequency of the acoustic emission signal measurement within a certain range (15% to 40% of the material level height), and can reflect the main internal information and flow conditions in the fluidized bed, so An acoustic emission signal receiving probe is installed at the wall of the distribution plate of the polyethylene fluidized bed reactor to 15% to 40% of the height H of the material in the bed, which can reduce hardware (probes) while obtaining the average information inside the fluidized bed investment; the receiving frequency range of the acoustic emission signal is 0Hz to 20MHz, and its optimal receiving frequency range is 0Hz to 1MHz. The acoustic emission signal enters the amplificat...
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Abstract
The invention discloses a determination method for a polyethylene fluidized bed bubble heat transfer coefficient. The method includes the steps of: 1) installing an acoustic emission signal receiving device on the wall of a polyethylene fluidized bed reactor; 2) carrying out wavelet decomposition or wavelet packet decomposition on a received acoustic emission signal, selecting characteristic values, and performing quantitative analysis of the particle size distribution in the reactor; 3) monitoring the particle size distribution of fluidized particles in the fluidized bed reactor in real time, when the mass fraction of particles greater than a critical particle size Ds exceeds 2 times that of normal production, taking the melting temperature of polyethylene as the emulsion phase temperature, and combining the space-time yield STY at the moment to calculate the bubble heat transfer coefficient under the polyethylene fluidized bed system. The method provided by the invention has the characteristics of simple and convenient installation, on-line detection, sensitive response, accurate measurement, safety and environmental protection, etc., and can be used for laboratory scale and industrial scale fluidized bed heat-transfer capability study and reactor design.
Description
technical field [0001] The invention relates to the detection of important characteristic parameters in a fluidized bed reactor, in particular to a method for measuring the heat transfer coefficient of gas-phase polyethylene fluidized bed bubbles. Background technique [0002] Polyethylene is the commercial synthetic polymer with the largest output in the world today. It is widely used in many fields such as plastic blown film, film and pipe. In 2014, its annual world output exceeded 100Mt. Due to the advantages of simple equipment and process, low energy consumption, high flexibility and good environmental compatibility, the fluidized bed reactor process has become the main way to produce polyethylene. According to statistics, currently the production capacity of polyethylene in fluidized bed reactors in the world accounts for nearly one-third of the total production capacity of polyethylene. In our country, the proportion of fluidized bed technology is larger, close to on...
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IPC IPC(8): G01N29/14
CPCG01N29/14G01N2291/02433
Inventor 王靖岱葛世轶杨遥黄正梁阳永荣蒋斌波廖祖维訾灿王浩同
Owner ZHEJIANG UNIV