METHANOL PRODUCTIVITY COMPARISON BETWEEN AN AGITATED SLURRY REACTOR AND AN ENTRAINED REACTOR

ABSTRACT

The effect of various operating conditions including the catalyst loading in slurry, on the productivity of methanol in an agitated slurry reactor were studied. The modeling of the mechanically agitated slurry reactor was performed with the aid of the reaction rate expression and the gas-liquid mass transfer correlation that were developed, to predict the rate of methanol production for any inlet condition

The equilibrium limitation encountered in the liquid phase methanol synthesis process in an agitated slurry reactor can be alleviated by conducting this process in an entrained reactor, where the product methanol formed is continuously flashed out of the system. After developing a kinetic rate expression and a gas-liquid mass transfer correlation, the modeling of the entrained reactor was performed to predict the reactor productivity for any process condition. The rate of methanol production predicted for nominally identical operating conditions in an entrained reactor and in a mechanically agitated slurry reactor are compared with the aid of the computer models developed     

MASS TRANSFER CCMPARISON BEIWEEN MECHANICALLY AGITATED SLURRY REACTCR AND LIQUID ENTRAINED REACTOR IN THE METHANOL SYNTHESIS PROCESS

The commercial reactor proposed for the liquid phase methanol synthesis process (LPMeCHTM) is a liquid entrained reactor (LER), since it possesses several operational advantages over a mechanically agitated slurry reactor (MASR). This paper discusses in detail the develocment of a correlation for the prediction of the overall gas-liquid mass transfer coefficient (KLiaB) in a LER. The overall mass transfer coefficient experimentally determined for the LER, is compared with the corresponding value obtained for the MASR under nominally identical operating conditions. It was observed that the overall gas-liquid mass transfer coefficient and hence the overall rate of methanol production per unit mass of catalyst, is significantly higher in the LER compared to the MASR at identical operating conditions. In the LER mode, the limitation posed on the system by chemical equilibrium, is alleviated by selective renewal of products thus making the process ideal for the once-through methanol (CIM) This justifies the proposed commercial mode of synthesis of methanol in the liquid entrained reactor.     

MASS TRANSFER CCMPARISON BEIWEEN MECHANICALLY AGITATED SLURRY REACTCR AND LIQUID ENTRAINED REACTOR IN THE METHANOL SYNTHESIS PROCESS

ABSTRACT

The commercial reactor proposed for the liquid phase methanol synthesis process (LPMeCHTM) is a liquid entrained reactor (LER), since it possesses several operational advantages over a mechanically agitated slurry reactor (MASR). This paper discusses in detail the develocment of a correlation for the prediction of the overall gas-liquid mass transfer coefficient (KLiaB) in a LER. The overall mass transfer coefficient experimentally determined for the LER, is compared with the corresponding value obtained for the MASR under nominally identical operating conditions. It was observed that the overall gas-liquid mass transfer coefficient and hence the overall rate of methanol production per unit mass of catalyst, is significantly higher in the LER compared to the MASR at identical operating conditions. In the LER mode, the limitation posed on the system by chemical equilibrium, is alleviated by selective renewal of products thus making the process ideal for the once-through methanol (CIM) This justifies the proposed commercial mode of synthesis of methanol in the liquid entrained reactor.     

STATISTICAL MODEL FOR SLURRY PHASE METHANOL SYNTHESIS PROCESS IN AN ENTRAINED REACTOR

The process feasibility analysis on the liquid phase methanol synthesis (LPMeOH) process was performed in an entrained slurry reactor system. In this three phase mini-pilot plant system, finely powdered catalyst is slurried in the inert oil phase and this catalyst-oil slurry is continuously recirculated through the entrained reactor, where it is contacted with the cocurrent flow of syngas to form the product methanol

The effect of various operating conditions which included the reactor temperature, the reactor pressure, the flow rate of catalyst-oil slurry, the flow rate of syngas, the slurry holdup tank pressure, the syngas composition, and the catalyst loadings in slurry, on the productivity of methanol in the reactor was studied. Using the operating conditions, a statistical reaction rate model not based on the kinetic mechanism, was developed to predict the productivity of methanol in an entrained reactor. The rate of production of methanol predicted by this model agreed well with the experimental results. This statistical model assists in the development, scale-up, and commercialization of the methanol synthesis process in an entrained slurry reactor.     

STATISTICAL MODEL FOR SLURRY PHASE METHANOL SYNTHESIS PROCESS IN AN ENTRAINED REACTOR

ABSTRACT

The process feasibility analysis on the liquid phase methanol synthesis (LPMeOH) process was performed in an entrained slurry reactor system. In this three phase mini-pilot plant system, finely powdered catalyst is slurried in the inert oil phase and this catalyst-oil slurry is continuously recirculated through the entrained reactor, where it is contacted with the cocurrent flow of syngas to form the product methanol

The effect of various operating conditions which included the reactor temperature, the reactor pressure, the flow rate of catalyst-oil slurry, the flow rate of syngas, the slurry holdup tank pressure, the syngas composition, and the catalyst loadings in slurry, on the productivity of methanol in the reactor was studied. Using the operating conditions, a statistical reaction rate model not based on the kinetic mechanism, was developed to predict the productivity of methanol in an entrained reactor. The rate of production of methanol predicted by this model agreed well with the experimental results. This statistical model assists in the development, scale-up, and commercialization of the methanol synthesis process in an entrained slurry reactor.     

LIQUID PHASE METHANOL SYNTHESIS IN AN ENTRAINED REACTOR—DEVELOPMENT OF A GAS-LIQUID MASS TRANSFER CORRELATION

Abstract

Research on various aspects of the methanol synthesis was performed in a liquid entrained reactor. The catalyst-oil slurry is pumped through the tubular entrained reactor and syngas is fed cocurrently with the upward flow of slurry. The effect of different operating conditions, syngas composition and catalyst loadings on the productivity of methanol, was studied.

The data obtained from the experiments at high catalyst loadings in slurry, was used to develop a gas-liquid mass transfer correlation for the liquid phase methanol synthesis in an entrained reactor. The productivity of methanol in an entrained reactor was then predicted using the developed mass transfer correlation. This predictive model also helps in the design, development, scale-up and commercialization of the liquid phase methanol synthesis process in an entrained reactor.     

MINI-PILOT PLANT DESIGN AMD OPERATION OF A LIQUID ENTRAINED REACTOR FOR LIQUID PHASE METHANOL SYNTHESIS PROCESS

The commercial reactor type proposed for the liquid phase methanol synthesis (LPMeOH™) process is a liquid entrained reactor (LER), mainly due to its higher methanol productivity and better capability of alleviating the chemical equilibrium limitation than a mechanically agitated slurry reactor (MASR). A laboratory scale mini-pilot plant version of a liquid entrained reactor system was successfully designed and built to carry out process engineering research, as well as to demonstrate the process feasibility of the LPMeOH™ process. This paper discusses in detail, the design philosophy of the liquid entrained reactor system and its accessory peripherals. The operation of the mini-pilot liquid entrained reactor system has also justified its effectiveness in pre-scaleup investigation of the energy conversion process, at a fraction of the cost required for a pilot scale investigation.     

MODELING OF A MECHANICALLY AGITATED SLURRY REACTOR FOR LIQUID PHASE METHANOL SYNTHESIS PROCESS

In the liquid phase methanol synthesis process in a mechanically agitated slurry reactor (MASR), catalyst particles in powder form are slurried in the oil phase, and this catalyst-oil slurry is continuously agitated by the impeller in the reactor. Syngas, which is fed to the reactor, reacts in the presence of the activated catalyst-oil slurry, to form the product, methanol.

A computer model was developed based on the experimental results, for the liquid phase methanol synthesis process, in a mechanically agitated slurry reactor. This computer program accurately predicts the multicomponent phase equilibria, ultimate chemical equilibria, and the compositions of each reactant and product species exiting in the agitated slurry reactor The results of the modeling predictions, agree well with the experimental data collected from the agitated slurry reactor.     

MODELING OF A MECHANICALLY AGITATED SLURRY REACTOR FOR LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT

In the liquid phase methanol synthesis process in a mechanically agitated slurry reactor (MASR), catalyst particles in powder form are slurried in the oil phase, and this catalyst-oil slurry is continuously agitated by the impeller in the reactor. Syngas, which is fed to the reactor, reacts in the presence of the activated catalyst-oil slurry, to form the product, methanol.

A computer model was developed based on the experimental results, for the liquid phase methanol synthesis process, in a mechanically agitated slurry reactor. This computer program accurately predicts the multicomponent phase equilibria, ultimate chemical equilibria, and the compositions of each reactant and product species exiting in the agitated slurry reactor The results of the modeling predictions, agree well with the experimental data collected from the agitated slurry reactor.     

KINETIC RATE EXPRESSION FOR METHANOL SYNTHESIS IN A LIQUID ENTRAINED REACTOR

In the three phase entrained reactor for the liquid phase synthesis of methanol, the catalyst-inert oil slurry is pumped through the tubular reactor and syngas is fed to the reactor cocurrently with the upward flow of slurry.

According to an elaborate experimental design plan, the effect of different operating conditions on the liquid phase synthesis of methanol in an entrained reactor, was studied. The parameters of this experimental study included reactor temperature, reactor pressure, slurry flow rate, syngas flow rate, slurry holdup tank pressure, and syngas composition.

The data obtained from the experiments at low catalyst loading in slurry, were used to develop a kinetic rate expression for the liquid phase methanol synthesis process in an entrained reactor. This in turn helps the scale-up and commercialization of the methanol synthesis process in an entrained reactor.     

KINETIC RATE EXPRESSION FOR METHANOL SYNTHESIS IN A LIQUID ENTRAINED REACTOR

Abstract

In the three phase entrained reactor for the liquid phase synthesis of methanol, the catalyst-inert oil slurry is pumped through the tubular reactor and syngas is fed to the reactor cocurrently with the upward flow of slurry.

According to an elaborate experimental design plan, the effect of different operating conditions on the liquid phase synthesis of methanol in an entrained reactor, was studied. The parameters of this experimental study included reactor temperature, reactor pressure, slurry flow rate, syngas flow rate, slurry holdup tank pressure, and syngas composition.

The data obtained from the experiments at low catalyst loading in slurry, were used to develop a kinetic rate expression for the liquid phase methanol synthesis process in an entrained reactor. This in turn helps the scale-up and commercialization of the methanol synthesis process in an entrained reactor.     

KINETICS OF METHANOL SYNTHESIS IN THE SLURRY PHASE

The kinetics of methanol synthesis, from synthesis gas, over a commercial Cu-Zn-Al catalyst, in a three phase slurry reactor was studied in a 1 liter, top agitated, baffled autoclave. From the rate data on methanol formation, a Langmuir-Hinshelwood type rate expression has been developed which is sufficient for desing calculations,process improvement, and optimization of operating conditions. The kinetic model developed is free from pore diffusional resistances and is not masked by any mass transfer effects. The results of this kinetic model are in good agreement with the experimental results.     

MASS TRANSFER IN THE LIQUID PHASE METHANOL SYNTHESIS PROCESS

The mass transfer characteristics of the liquid phase methanol synthesis process were experimentally investigated using a one-liter, mechanically agitated slurry reactor. The CuO/ZnO/Al₂O₃ catalyst was crushed to -140 mesh and suspended in an inert mineral oil (Witco # 40). The catalyst loading was varied within limits of experimental feasibility. The effects of temperature, pressure, level of oil, impeller speed, and gas flow rate on the overall gas-liquid mass transfer coefficient K_Lia_B were studied

The results obtained using a two-level, half-fractional factorial design of experiments indicated that the impeller speed, feed flow rate, and temperature had significant effects on the mass transfer coefficient at the experimental conditions examined. Correlations were developed for the Sherwood number based on the Reynolds number, the Schmidt number, the reciprocal gas flow number, the gas-liquid viscosity ratio, and the dimensionless temperature. A simplified power-law type approach was also used to correlate the overall gas-liquid mass transfer coefficient with the impeller speed, gas flow rate, and dimensionless temperature.     

KINETICS OF METHANOL SYNTHESIS IN THE SLURRY PHASE

ABSTRACT

The kinetics of methanol synthesis, from synthesis gas, over a commercial Cu-Zn-Al catalyst, in a three phase slurry reactor was studied in a 1 liter, top agitated, baffled autoclave. From the rate data on methanol formation, a Langmuir-Hinshelwood type rate expression has been developed which is sufficient for desing calculations,process improvement, and optimization of operating conditions. The kinetic model developed is free from pore diffusional resistances and is not masked by any mass transfer effects. The results of this kinetic model are in good agreement with the experimental results.     

MASS TRANSFER IN THE LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT

The mass transfer characteristics of the liquid phase methanol synthesis process were experimentally investigated using a one-liter, mechanically agitated slurry reactor. The CuO/ZnO/Al₂O₃ catalyst was crushed to -140 mesh and suspended in an inert mineral oil (Witco # 40). The catalyst loading was varied within limits of experimental feasibility. The effects of temperature, pressure, level of oil, impeller speed, and gas flow rate on the overall gas-liquid mass transfer coefficient K_Lia_B were studied

The results obtained using a two-level, half-fractional factorial design of experiments indicated that the impeller speed, feed flow rate, and temperature had significant effects on the mass transfer coefficient at the experimental conditions examined. Correlations were developed for the Sherwood number based on the Reynolds number, the Schmidt number, the reciprocal gas flow number, the gas-liquid viscosity ratio, and the dimensionless temperature. A simplified power-law type approach was also used to correlate the overall gas-liquid mass transfer coefficient with the impeller speed, gas flow rate, and dimensionless temperature.     

MODELING OF A LIQUID ENTRAINED REACTOR FOR LIQUID PHASE METHANOL SYNTHESIS PROCESS

The liquid phase methanol (LPMeOH^TM) synthesis process is to be commercially carried out in a liquid entrained reactor (LER), where the catalyst-inert oil slurry is pumped through the reaction zone along with the syngas fed separately. A computer model was developed based on the experimental results, for the LPMeOH^TM process in a liquid entrained reactor. This computer program accurately predicts the multicomponent phase equilibria, ultimate chemical equilibria and the compositions of each reactant and product species exiting in the entrained reactor. The prediction of the results of this modeling agrees well with the experimental data from the LaPorte pilot plant entrained reactor.     

MODELING OF A LIQUID ENTRAINED REACTOR FOR LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT

The liquid phase methanol (LPMeOH^TM) synthesis process is to be commercially carried out in a liquid entrained reactor (LER), where the catalyst-inert oil slurry is pumped through the reaction zone along with the syngas fed separately. A computer model was developed based on the experimental results, for the LPMeOH^TM process in a liquid entrained reactor. This computer program accurately predicts the multicomponent phase equilibria, ultimate chemical equilibria and the compositions of each reactant and product species exiting in the entrained reactor. The prediction of the results of this modeling agrees well with the experimental data from the LaPorte pilot plant entrained reactor.     

浆态床甲醇合成过程工艺研究

对浆态床内液相甲醇合成过程进行研究 ,分析不同操作条件对反应过程的影响 ,并重点考察传质过程对反应的影响 ,为确定浆态床甲醇合成工业化生产最佳反应条件提供了基础实验数据。实验结果表明 ,CO转化率随温度的变化存在一个最优区域 ,而随压力的升高单调增大 ;原料气空速的增大虽然可提高甲醇的产率 ,但同时会降低CO的转化率 ;对于浆态床体系 ,最优氢碳摩尔比大于 2 /1;浆态床可通过改善传质效果达到进一步提高CO转化率的目的。     

过滤-反应耦合的高效浆态床反应器的开发

浆态床反应器因传质性能优异而应用广泛,但因采用细粉微球催化剂,高效固液分离是保障其长周期稳定运行的技术关键,这对大处理量的浆态床蒽醌法生产双氧水技术开发尤为重要。通过一系列冷模试验,对催化剂平均粒径、过滤材料孔径、搅拌桨叶端线速度、过滤压差等因素影响过滤通量的规律进行了详细研究,开发出了一种集反应、过滤、气液分离于一体的高效浆态床反应器。将该浆态床反应器应用到烷基蒽醌加氢过程中,开展热模评价试验,连续稳定运转1 000 h,无需反冲操作仍可保持高通量过滤,验证了所开发的高效浆态床反应器的可行性。     

IN-SITU ACTIVATION OF METHANOL SYNTHESIS CATALYST IN A THREE-PHASE SLURRY REACTOR

In the liquid phase methanol synthesis process, syngas reacts in the presence.of fine catalyst particles slurried in the oil phase, in a three phase slurry reactor system. A method for activating high concentration ( ≤25 wt. %) of the CuO-ZnO-Al₂O₃ catalyst in the catalyst-oil slurry has been successfully developed. This catalyst activation process can be of crucial significance in the research and development of the methanol synthesis process in a liquid entrained reactor.

The reducing gas contains 2% hydrogen in nitrogen mixture and this activation procedure is carried out at a pressure of 125 psi. The catalyst-oil slurry is subjected to a controlled temperature ramping from 110° to 250° C. The catalyst has beemshown to be effectively reduced after following this activation procedure, that is valid especially for high catalyst loadings in slurry. Since the reduction is carried out in the process liquid medium and inside the reactor system, the catalyst-oil slurry after the treatment is ready for the synthesis of methanol.