Fast Determination of Catalyst Active Coefficient in A Continuoud Ammonia Synthesis Reactor
0
Citation
0
Reference
20
Related Paper
Abstract:
Taking the typical three-tube co-current ammonia synthesis reactor in a middle-size ammonia synthesis plant of our country as an example, the mathematical models of the reactor were employed to simulate the reactor operation calculation. The calculated sensitive parameters of inlet temperature, outlet temperature, inlet vacant velocity and outlet ammonia molar fraction of the catalyst bed and the daily ammonia output can be compared with those measured in industrial production to simply and quickly determine the catalyst active (coefficients) during different production periods,which has an important significance to instruct industrial (ammonia) production and ammonia synthesis reactor design.Keywords:
Ammonia production
Molar ratio
Fraction (chemistry)
Cite
Isothermal process
Microreactor
Cite
Citations (59)
Through the mathematical simulation calculation, the influences of ammonia content, inert gas content, their temperature at the inlet of catalyst bed, space velocity and active coefficients of catalyst on ammonia synthesis reaction and their inherent relations were quantitatively analyzed and discussed for the three jacketed tube type of ammonia converter under the conditions of definite design pressure, hot point temperature and hydrogen/nitrogen ratio; also the theoretical basis and method to realize the optimal operation of ammonia converter under the most optimal control parameters and to determine more suitable process design parameters of ammonia converter were presented. The result indicates that temperature at the inlet of catalyst bed is the most optimal control parameter to realize the optimal operation of ammonia converter.
Space velocity
Inert
Ammonia production
Catalytic converter
Optimal design
Cite
Citations (0)
Mathematical modeling was used to develop and study an automated control system (ASU) for the temperature conditions of a high-yield ammonia synthesis reactor. The dynamic characteristics of the catalyst granule and catalyst bed were studied. Control channels were selected. It is shown that reference calculations for adjusting ASU's can be done when the dynamics of the catalyst beds are described by a quasihomogeneous model with subsequent refinement using a model which takes into account external heat exchange between the granule surface and gas flow and lengthwise heat transfer through the catalyst shell.
Ammonia production
Granule (geology)
Cite
Citations (0)
The new compound reactor that combines the entrained-flow reactor and slurry reactor was studied.CO hydrogenation was observed in the entrained-flow part of the new reactor,and the effect of different operation parameters on the synthesis process was analyzed.The effects of temperature,pressure and space velocity on the concentration and space time yield of the product in the outlet gas were discussed.The longitudinal and the radial temperature distribution of the reactor were also determined.The results showed that there is an optimum temperature range in which product yield can reach a maximum,and it increases with the increase of reaction pressure.Under the certain circulation of catalyst slurry,large space velocity of syngas can really advance product yield,but it decreases the concentration of product in the outlet gas.When the syngas flux is definite,there is an optimum circulation of catalyst slurry,and the concentration of product in the outlet gas and the product yield will decline if the circulation is enlarged more than the optimum value.The distribution profiles of the longitudinal temperature and radial temperature of the reactor were flat and the temperature of the reactor is easy to be controlled.
Space velocity
Cite
Citations (0)
Monolith
Honeycomb
Nitric acid
Oxidation process
Catalytic Oxidation
Honeycomb structure
Cite
Citations (7)
The relationships of particle axial distribution in the bubble column slurry reactor for the synthesis of methanol with various parameters, such as superficial gas velocity, reactor diameter and catalyst concentration, were discussed by means of a mathematical model verified by model test.The influence of the main construction parameters of the reactor and the operating parameters of industrial demonstration unit of 10000?t·a -1 were determined.The modeling results obtained under the conditions of two industrial synthesis gases showed that the influence of pressure in three-phase methanol synthesis process was most obvious, and slurry bed height was also a more important adjustable parameter.Under the operating condition in this paper, as methanol yield reaches 10000 tons per year, outlet methanol mole fractions is in the range from 0.07 to 0.10 and CO conversion is in the range from 40% to 50% within wider ranges of pressure and temperature with recycle and once-through of synthesis gases.
Bubble column reactor
Particle (ecology)
Cite
Citations (0)
Plug flow
Cite
Citations (16)
Ammonia production from synthesis gas is one of the most important processes in the petrochemical industry. A heterogeneous model is used to improve the efficiency of an industrial ammonia synthesis reactor including three adiabatic catalyst beds. In this model, the effectiveness factor was determined by considering the diffusion reaction equation. Reasonable agreement was achieved between simulated results and industrial data in terms of reactor component mole fraction and temperature. This mathematical model was modified to use for improving the ammonia converter performance and predict the effectiveness factors, nitrogen fractional conversion, temperature, and hydrogen and ammonia mole fraction profiles. The competency of the modified model has been investigated for industrial application by manipulating the reactor operation conditions and observing their effects on reactor output and results revealed the reliability of the developed model. The model is employed to obtain the optimum temperature profiles of each catalyst bed in the reactor based on equilibrium curve of ammonia synthesis reaction. Operating condition of the reactor was changed to achieve the optimum temperature profile according to model results by manipulating the reactor quench valves. After implementing changes in the reactor, the reactor performance and efficiency has improved with increasing ammonia conversion from 15.26% to 15.45% that increases ammonia production by 3t/d and energy saving by 1.66 Gj/h. The differential temperature of the first catalyst bed significantly increased by 6 °C and overall differential temperature through ammonia converter is increased by around 4 °C. This increases steam production by 2 t/h through loop boiler.
Ammonia production
Mole fraction
Petrochemical
Cite
Citations (28)
Modelling of catalytic ammonia oxidation reactor for nitric oxide production in nitric acid plant over gauzes of Pt/Rh catalyst was the subject of current study. Viscosity, mass transfer and kinetic equations were used for the gas mixture feeding the reactor, partial pressure and mole fraction of ammonia was essential, also wire diameter was considered to detect platinum losses during oxidation operation. In order to investigate the performance of catalytic oxidation reactor, ordinary equation for determining of conversion yields of ammonia to nitric oxide was solved in mathematical model numerically. Variations of conversion with inlet mixture temperature, mixture concentration, inlet pressure and gauze temperature during cycle were investigated. Platinum losses rate as platinum oxide (PtO2) was studied with gauzes surface temperature by using numerical solution of the mathematical model. Modelling results were compared with an industrial reactor data. Comparing industrial data for all studied variables with those obtained by using mathematical model have shown the higher degree of accuracy of the model to predict the operating values with minimum deviation.
Nitric acid
Cite
Citations (4)
To perform the catalytic conversion of natural gas to synthesis gas, a compact radial reactor supplied with a structured porous metal catalyst has been designed. The reactor was tested at normal pressure using natural gas and air. The reactor can operate without preheating of the inlet gas mixture. A novel structured porous metal catalyst was developed on the basis of the 7% Ni/α-Al2O3 commercial catalyst and Ni−Cr powders. The catalyst is characterized by a low hydraulic pressure drop and a high tortuosity coefficient of the regular structure. The coefficient of heat conductivity of the structured catalyst and the coefficient of mass transfer between a gas flow and the catalyst were determined in special experiments. The catalyst temperature and outlet gas concentrations were experimentally investigated with respect to the gas−air flow rate and methane concentration in the mixture. The catalyst temperature drop along the reactor radius was no higher than 230 °C. The maximum catalyst temperature does not exceed 1090 °C for all runs. At volumetric flow rates of the gas mixture of 4000−40 000 h-1 and O2/CH4 ratios of 0.6−0.9, methane is completely converted, and the maximum space time yield (STY) of the reactor is about 1 L of CH4 per second per liter of reactor. A mathematical model for this process was developed. The results of modeling agree well with the experimental data. One possible application of the developed syngas generator in internal combustion engines is discussed.
Space velocity
Cite
Citations (12)