The modified grain model applied to regeneration of a coked fixed-bed reactor the catalytic effect of chromium on the coke burn-off reaction

1996 ◽  
Vol 145 (1-2) ◽  
pp. 285-295 ◽  
Author(s):  
A BRITO ◽  
R ARVELO ◽  
F GARCIA ◽  
A GONZALEZ
Keyword(s):  
Catalytic Effect ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Grain Model

An Experimental Study on N2O Reduction Over Circulating Ashes of CFB Boilers

2005 ◽  
Author(s):  
Hai Zhang ◽  
Junfu Lu ◽  
Keyu Chen ◽  
Hairui Yang ◽  
Guangxi Yue
Keyword(s):  
Experimental Study ◽  
Reaction Temperature ◽  
Catalytic Effect ◽  
Circulating Fluidized Bed ◽  
Fixed Bed ◽  
N2o Emission ◽  
Fixed Bed Reactor ◽  
Operational Parameters ◽  
N2o Reduction ◽  
O2 Concentration

An experimental study on nitrous oxide (N2O) reduction with circulating ashes of circulating fluidized bed (CFB) boilers was conducted for the development of an effective and economical technology to reduce the N2O emission from CFB boilers. The experiments were conducted with three kinds of circulating ashes, by using a fixed bed reactor with a diameter of 25mm, under various conditions of different operational temperatures, initial N2O concentrations, NH3 additions and O2 concentrations. The effects on N2O reduction were compared that with quartz sand. The experimental results showed that circulating ashes may possess remarkable catalytic effect on N2O reduction and the intensity of the catalytic effect strongly depends on operational parameters such as reaction temperature and O2 concentration. It was also found nitric oxide (NO) was produced during the process of N2O reduction and its concentration also strongly affected by reaction temperature and O2 concentration. The mechanisms of N2O reduction were discussed. The study confirmed the feasibility of injecting NH3 at the cyclone entrance of CFB boiler to form a selective catalytic reduction (SCR) process for N2O emission without using extra catalyst and provided some guidance to choose the operational parameters for N2O reduction with circulating ashes.

scholarly journals Catalytic pyrolysis of agricultural and forestry wastes in a fixed-bed reactor using K2CO3 as the catalyst

2019 ◽  
Vol 38 (1) ◽  
pp. 78-87
Author(s):  
Haojie Fan ◽  
Xuelun Chang ◽  
Jie Wang ◽  
Zhongxiao Zhang
Keyword(s):  
Rice Straw ◽  
Catalytic Pyrolysis ◽  
Catalytic Effect ◽  
Fixed Bed ◽  
The Other ◽  
Fixed Bed Reactor ◽  
Peanut Shell ◽  
Temperature Range ◽  
Significant Difference ◽  
Liquid Yield

Catalytic pyrolysis of three different agricultural and forestry wastes (pinewood, peanut shell, rice straw) was performed in a fixed-bed reactor heated slowly under a stream of purging argon in the temperature range from 300 °C to 700 °C using K2CO3 as the catalyst. The aim of this study is to investigate the gaseous, liquid, and solid products derived from three different biomasses, and to ascertain the effects of K2CO3 on the pyrolysis behaviours. The products’ yields correlated with the composition of the biomasses and the addition of catalyst in the biomasses. The addition of K2CO3 described a strong catalysis in all three phases of the products: The liquid yield decreased obviously in contrast to the increase in gas yield. The liquid yields of pinewood and peanut shell demonstrated a remarkable decrease, while that of rice straw demonstrated the least decrease owing to a significant difference between the fibre composition of rice straw and those of the other two biomasses. This catalytic pyrolysis procedure was observed to produce low yields of liquid that contained high proportions of ketones and phenols, with minor acids, aldehydes, and furans. Among the three, the phenols of rice straw indicated the most obvious increase, while guaiacols decreased significantly, indicating that K2CO3 facilitated the secondary decomposition of guaiacols. Generally, for K2CO3 catalyst, the order of catalytic effect was pinewood > peanut shell > rice straw.

Role of filter media in an anaerobic fixed-bed reactor

1995 ◽  
Vol 31 (9) ◽  
pp. 137-144 ◽  
Author(s):  
T. Miyahara ◽  
M. Takano ◽  
T. Noike
Keyword(s):  
Anaerobic Bacteria ◽  
Fixed Bed ◽  
Methanogenic Bacteria ◽  
The Other ◽  
Fixed Bed Reactor ◽  
Filter Media ◽  
Fixed Bed Reactors ◽  
Attached Bacteria ◽  
The Relationship

The relationship between the filter media and the behaviour of anaerobic bacteria was studied using anaerobic fixed-bed reactors. At an HRT of 48 hours, the number of suspended acidogenic bacteria was higher than those attached to the filter media. On the other hand, the number of attached methanogenic bacteria was more than ten times as higher than that of suspended ones. The numbers of suspended and deposited acidogenic and methanogenic bacteria in the reactor operated at an HRT of 3 hours were almost the same as those in the reactor operated at an HRT of 48 hours. Accumulation of attached bacteria was promoted by decreasing the HRT of the reactor. The number of acidogenic bacteria in the reactor packed sparsely with the filter media was higher than that in the closely packed reactor. The number of methanogenic bacteria in the sparsely packed reactor was lower than that in the closely packed reactor.

Modeling of aerated upflow fixed bed reactors for nitrification

1999 ◽  
Vol 39 (4) ◽  
pp. 85-92 ◽  
Author(s):  
J. Behrendt
Keyword(s):  
Mathematical Model ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Gas Phase ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Bulk Liquid ◽  
Initial Value ◽  
Fixed Bed Reactors ◽  
Number Of Cells

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.

Design of a continuous flow immobilized-cell reactor for biosynthetical production of L-aspartic acid

1985 ◽  
Vol 50 (10) ◽  
pp. 2122-2133 ◽  
Author(s):  
Jindřich Zahradník ◽  
Marie Fialová ◽  
Jan Škoda ◽  
Helena Škodová
Keyword(s):  
Aspartic Acid ◽  
Continuous Flow ◽  
Immobilized Cells ◽  
Scale Up ◽  
Fixed Bed ◽  
Packed Bed ◽  
Fixed Bed Reactor ◽  
Experimental Program ◽  
Design Parameters ◽  
Immobilized Cell

An experimental study was carried out aimed at establishing a data base for an optimum design of a continuous flow fixed-bed reactor for biotransformation of ammonium fumarate to L-aspartic acid catalyzed by immobilized cells of the strain Escherichia alcalescens dispar group. The experimental program included studies of the effect of reactor geometry, catalytic particle size, and packed bed arrangement on reactor hydrodynamics and on the rate of substrate conversion. An expression for the effective reaction rate was derived including the effect of mass transfer and conditions of the safe conversion-data scale-up were defined. Suggestions for the design of a pilot plant reactor (100 t/year) were formulated and decisive design parameters of such reactor were estimated for several variants of problem formulation.

scholarly journals Bio-Oil Characterizations of Spirulina Platensis Residue (SPR) Pyrolysis Products for Renewable Energy Development

2020 ◽  
Vol 849 ◽  
pp. 47-52
Author(s):  
Siti Jamilatun ◽  
Aster Rahayu ◽  
Yano Surya Pradana ◽  
Budhijanto ◽  
Rochmadi ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Spirulina Platensis ◽  
Pyrolysis Temperature ◽  
Renewable Energy Sources ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Oil Yield ◽  
Optimum Temperature ◽  
Pyrolysis Products ◽  
Bio Oil

Nowadays, energy consumption has increased as a population increases with socio-economic developments and improved living standards. Therefore, it is necessary to find a replacement for fossil energy with renewable energy sources, and the potential to develop is biofuels. Bio-oil, water phase, gas, and char products will be produced by utilizing Spirulina platensis (SPR) microalgae extraction residue as pyrolysis raw material. The purpose of this study is to characterize pyrolysis products and bio-oil analysis with GC-MS. Quality fuel is good if O/C is low, H/C is high, HHV is high, and oxygenate compounds are low, but aliphatic and aromatic are high. Pyrolysis was carried out at a temperature of 300-600°C with a feed of 50 grams in atmospheric conditions with a heating rate of 5-35°C/min, the equipment used was a fixed-bed reactor. The higher the pyrolysis temperature, the higher the bio-oil yield will be to an optimum temperature, then lower. The optimum temperature of pyrolysis is 550°C with a bio-oil yield of 23.99 wt%. The higher the pyrolysis temperature, the higher the H/C, the lower O/C. The optimum condition was reached at a temperature of 500°C with the values of H/C, and O/C is 1.17 and 0.47. With an increase in temperature of 300-600°C, HHV increased from 11.64 MJ/kg to 20.63 MJ/kg, the oxygenate compound decreased from 85.26 to 37.55 wt%. Aliphatics and aromatics increased, respectively, from 5.76 to 36.72 wt% and 1.67 to 6.67 wt%.

Sign in / Sign up

Export Citation Format

Share Document