Wen Jianping

Local hydrodynamics in a gas-liquid-solid three-phase bubble column reactor

A two-dimensional pseudo-two-phase fluid dynamic model with included turbulence model was used to calculate local values of axial liquid velocity and gas holdup in a concurrent gas-liquid-solid three-phase bubble column reactor. The simulated results agreed well with the experimental data. The effects of the solids loading, superficial liquid velocity and superficial gas velocity on the local axial liquid velocity and local gas holdup were experimentally and theoretically examined.

Performance of a new vapor–liquid–solid three-phase circulating fluidized bed evaporator

Abstract In order to enhance heat transfer and solve the fouling problems in boiling processes, a new vapor–liquid–solid three-phase circulating fluidized bed evaporator was developed by adding solid particles to the boiling liquid. In this paper, the experimental studies on the performances of this evaporator—such as heat transfer, pressure drop, fouling prevention and removal—power consumption of recycle pump were carried out. Based on the analysis of the heat transfer characters of these three-phase flow boiling experiment, a mathematical model for predicting the flow boiling heat transfer coefficients of this evaporator is proposed. The predicted results of the flow boiling heat transfer coefficients agree well with the experimental data. The quality of NaCl product obtained in this evaporator achieves the state standard of the Peoples Republic of China.

The denitrification of nitrate contained wastewater in a gas–liquid–solid three-phase flow airlift loop bioreactor

Denitrification of nitrified effluent with high concentration of nitrate, low COD in fertilizer plant was carried out in a 12-1 gas-liquid-solid three-phase flow airlift loop bioreactor, in which biological membrane replace the activated sludge. The influences of pH, temperature, C/N ratio, gas-liquid ratio and HRT on the removal of nitrate-nitrogen were investigated and discussed. The optimum operation conditions were obtained as pH value of 6.5-7.5, temperature of 20-35 °C, C/N ratio of 0.95-1, gas-liquid ratio of 62.5 and HRT of 2.5 h. Under optimum operation conditions, the average removal efficiencies of COD and NO x -N are higher than 93 and 96%, corresponding to the effluent concentrate of nitrate <20 mg/l and COD <40 mg/l. The radial and axial positions have little influence on the local profiles of COD and NO x -N.

Solid–liquid mass transfer in a gas–liquid–solid three-phase reversed flow jet loop reactor

Abstract Solid–liquid mass transfer in gas–liquid–solid three-phase reversed flow jet loop reactors was experimentally investigated by means of an electrochemical method, and the effects of liquid jet flow rate, gas jet flow rate, particle size, particle density and nozzle diameter on the solid–liquid mass transfer coefficient were evaluated. The solid–liquid mass transfer coefficients in gas–liquid–solid three-phase reversed flow jet loop reactors are higher than those in the corresponding liquid–solid two-phase reversed flow jet loop reactors. A generalized correlation is developed which more accurately and conveniently predicts solid–liquid mass transfer in gas–liquid–solid three-phase reversed flow jet loop reactors.

The preparation of 2-chloro-5-methyl-pyridine in airlift loop reactor

A new process for the direct chlorination of 3-methyl-pyridine with special catalyst to yield 2-chloro-5-methyl-pyridine in the airlift loop reactor has been considered. The effects of reaction temperature, the molar ratio of palladium chloride to 3-methyl-pyridine, concentration of 3-methyl-pyridine, chlorine gas flowrate and the ratio of the inside diameter of the draft tube to that of the reactor on the molar yield of 2-chloro-5-methyl-pyridine were investigated and discussed, and an optimum operation condition was found. The average molar yield of 2-chloro-5-methyl-pyridine comes up to 60% under the optimum operation condition.

Local overall volumetric gas-liquid mass transfer coefficients in gas-liquid-solid reversed flow jet loop bioreactor with a non-Newtonian fluid.

The local overall volumetric gas-liquid mass transfer coefficients at the specified point in a gas-liquid-solid three-phase reversed flow jet loop bioreactor (JLB) with a non-Newtonian fluid was experimentally investigated by a transient gassing-in method. The effects of liquid jet flow rate, gas jet flow rate, particle density, particle diameter, solids loading, nozzle diameter and CMC concentration on the local overall volumetric gas-liquid mass transfer coefficient (K(L)a) profiles were discussed. It was observed that local overall K(L)a profiles in the three-phase reversed flow JLB with non-Newtonian fluid increased with the increase of gas jet flow rate, liquid jet flow rate, particle density and particle diameter, but decreased with the increase of the nozzle diameter and CMC concentration. The presence of solids at a low concentration increased the local overall K(L)a profiles, and the optimum of solids loading for a maximum profile of the local overall K(L)a was found to be 0.18x10(-3)m(3) corresponding to a solids volume fraction, varepsilon(S)=2.8%.

FLOW BOILING HEAT TRANSFER IN A NEW VAPOR-LIQUID-SOLID THREE-PHASE CIRCULATING FLUIDIZED BED EVAPORATOR

In order to enhance heat transfer and solve the fouling problems in boiling processes, a boiling system was designed by adding solid particles to the boiling liquid. In this paper, both theoretical analyses and experimental studies on the flow boiling heat transfer in a vapor-liquid-solid three-phase circulating fluidized bed evaporator were carried out. Based on the analysis of the heat transfer characters of this three-phase flow boiling, a mathematical model for predicting the flow boiling heat transfer coefficients of the vapor-liquid-solid three-phase circulating fluidized bed evaporator was developed. The experiments show that, in the presence of solid particles the flow boiling heat transfer is enhanced and is about 2 times that of the vapor-liquid two-phase one. The predicted results of the flow boiling heat transfer coefficients agreed well with the experimental data.

LOCAL LIQUID SIDE MASS TRANSFER MODEL IN AIRLIFT LOOP REACTOR AND SELF-ASPIRATED REVERSED FLOW JET LOOP REACTOR

ABSTRACT Combining Higbies penetration theory and Kolmogoroffs theory of isotropic turbulence, a small-scale isotropic mass transfer model for the local liquid side mass transfer coefficients in a gas-liquid two-phase airlift loop reactor and a self-aspirated reversed flow jet loop reactor has been developed. Good agreement with the experimental data suggests a general applicability of the proposed model in these reactors.

The Preparation of Imidacloprid in a Jet Loop Reactor

Abstract A new process for the direct combination of 2-chloro-5-chloromethylpyridine and 2-nitroiminoimidazolidine under benzyltriethylammonium chloride (BTEAC) as the catalyst and butanone as the solvent to yield imidacloprid in an 11.5 L jet loop reactor was developed. Five main reaction conditions including reaction temperature, molar ratio of BTEAC to 2-nitroiminoimidazolidine, concentration of 2-nitroiminoimidazolidine, jet liquid flow rate, and the ratio of the inside diameter of the draft tube to that of the reactor were investigated and optimized. The average molar yield and purity of imidacloprid increased to approximately 80% and 92% under the optimum operating conditions, respectively. Finally, a comparison of the efficiency for the preparation of imidacloprid between the jet loop reactor and the stirred tank reactor under the same operating conditions was conducted.

LOCAL OVERALL GAS–LIQUID VOLUMETRIC MASS TRANSFER COEFFICIENTS IN A GAS–LIQUID TWO-PHASE REVERSED FLOW JET LOOP REACTOR

Local overall gas-liquid volumetric mass transfer coefficient profiles at the specified point were experimentally investigated in a gas–liquid two-phase reversed flow jet loop reactor with Newtonian and non-Newtonian systems. It was observed that the local overall gas-liquid volumetric mass transfer coefficient profiles of this reactor with Newtonian and non-Newtonian systems increase with increase in gas jet flow rates and liquid jet flow rates, and with decrease in nozzle diameter and CMC concentration.