Efficiency Improvement in Entrained Flow Gasification

2011 ◽  
Author(s):  
Ankit Bhatnagar ◽  
S. Pushpavanam
Keyword(s):  
Oxygen Consumption ◽  
Single Stage ◽  
Stage Model ◽  
Two Stage ◽  
Entrained Flow ◽  
Second Stage ◽  
Cold Gas Efficiency ◽  
Stage System ◽  
Gas Efficiency ◽  
Cold Gas

In this work a one dimensional steady state model is developed for a single stage and two-stage bottom fed entrained flow coal gasifier for. The single stage model was first analysed for two different oxidants (i) oxygen and (ii) air to study their effects on gasification. Analysis proved oxygen to be the better oxidant. The model is then extended to a two stage gasifier. Here 30 (70) percent of the coal is fed in the first stage (second stage). The first (second) stage operates in oxidant rich (lean) environment. The performances of single stage and two-stage models are compared in terms of their cold gas efficiencies for the same coal feed rates. It is observed that a two-stage system has better cold gas efficiency (77%) than a single stage system (72%) with lower oxygen consumption. The two-stage model is used to optimise the O2/Coal ratio as the H2O/Coal ratio is varied in the 2nd stage. The optimum yields the highest cold gas efficiency with minimum possible oxygen consumption.

Study on Gasification Characteristics of Petroleum Asphalt in a Two-Stage Gasifier

2014 ◽  
Vol 953-954 ◽  
pp. 1673-1677
Author(s):  
Guang Yu Li ◽  
Shi Sen Xu ◽  
Jun Cang Xia ◽  
Yong Qiang Ren
Keyword(s):  
Bituminous Coal ◽  
Heterogeneous Reaction ◽  
Reaction Model ◽  
Utilization Rate ◽  
Two Stage ◽  
Petroleum Asphalt ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Gas Efficiency ◽  
Cold Gas

The gasification performance of petroleum asphalt in a two-stage gasifier was investigated through experiments and simulations. The analysis results of asphalt samples show that the asphalt has characteristics of high volatile content, high calorific value, and low ash content. Coal pyrolysis model, gas-solid heterogeneous reaction model, gas homogeneous reaction model and Gibbs free energy minimization method were employed to build the two-stage entrained flow gasification model and simulate the asphalt gasification process using Aspen Plus software. The results indicate that the cold gas efficiency of asphalt is 3% higher than that of bituminous coal, while the consumption of coal and oxygen is 40% lower than that of bituminous coal. The gasification performance of asphalt is superior to that of coal. In addition, the cold gas efficiency of asphalt can be increased by about 3% when the two-stage gasification process is employed. The utilization rate of coal in the two-stage gasifier is much higher than that in traditional one-stage gasifier.

Characteristic Research on CaO Sorption Enhanced Biomass Directional Entrained-Flow Gasification

2014 ◽  
Vol 953-954 ◽  
pp. 211-215
Author(s):  
Chao Chen ◽  
Jin Song Zhou ◽  
Yang Yang Xiang ◽  
Zhong Yang Luo
Keyword(s):  
Influence Factors ◽  
Energy Utilization ◽  
Liquid Fuels ◽  
Temperature Ratio ◽  
Entrained Flow ◽  
Cold Gas Efficiency ◽  
Gas Efficiency ◽  
Entrained Flow Gasification ◽  
Gasification Temperature ◽  
Cold Gas

As the only renewable energy which can be converted into liquid fuels, biomass has developed various technologies of energy utilization. In order to adjust the syngas composition, increase the ratio of H2/CO and reduce CO2 content, this paper conducted biomass gasification experiment in an entrained flow bed on CaO sorption. The paper studied influence factors like the gasification temperature, ratio of CaO/B and gasification parameters, such as ratio of H2/CO, cold gas efficiency, cold gas yield or tar content in syngas. The result showed that raising gasification temperature or increasing added content of CaO which were beneficial to the improvement of H2 content. A maximum H2 output with a concentration of 62.7% and H2/CO ratio of 3.19 was achieved at CaO/C=1, H2O/B=0.3 and T=1100°C, meanwhile the cold gas efficiency was 86.07%, the cold gas yield reached 1.2Nm3/kg biomass, and the tar content was dropped to 314.6mg/Nm3.

The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity

1998 ◽  
Vol 38 (4-5) ◽  
pp. 29-35 ◽  
Author(s):  
C. J. Banks ◽  
P. N. Humphreys
Keyword(s):  
Ph Control ◽  
Anaerobic Treatment ◽  
Buffering Capacity ◽  
Single Stage ◽  
Stable Operation ◽  
Reactor Performance ◽  
Two Stage ◽  
Ph Buffering ◽  
Stage System ◽  
The Stability

The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.

scholarly journals Analysis of coal gasifier performance. Quantitative evaluation of development subjects and the analysis of factors influencing cold gas efficiency.

1985 ◽  
Vol 64 (9) ◽  
pp. 716-733
Author(s):  
Takehiko FURUSAWA ◽  
Toshinori KOJIMA ◽  
Seiji TOKAWA ◽  
Shuichi TANAKA ◽  
Takuya KAWANISHI ◽  
...  
Keyword(s):  
Quantitative Evaluation ◽  
Cold Gas Efficiency ◽  
Coal Gasifier ◽  
Factors Influencing ◽  
Gas Efficiency ◽  
Cold Gas

scholarly journals Two-Stage Fuzzy Portfolio Selection Problem with Transaction Costs

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yanju Chen ◽  
Ye Wang
Keyword(s):  
Transaction Costs ◽  
Portfolio Selection ◽  
Optimal Solution ◽  
Single Stage ◽  
Selection Problem ◽  
Stage Model ◽  
Two Stage ◽  
Portfolio Selection Problem ◽  
Fuzzy Portfolio Selection ◽  
Proposed Model

This paper studies a two-period portfolio selection problem. The problem is formulated as a two-stage fuzzy portfolio selection model with transaction costs, in which the future returns of risky security are characterized by possibility distributions. The objective of the proposed model is to achieve the maximum utility in terms of the expected value and variance of the final wealth. Given the first-stage decision vector and a realization of fuzzy return, the optimal value expression of the second-stage programming problem is derived. As a result, the proposed two-stage model is equivalent to a single-stage model, and the analytical optimal solution of the two-stage model is obtained, which helps us to discuss the properties of the optimal solution. Finally, some numerical experiments are performed to demonstrate the new modeling idea and the effectiveness. The computational results provided by the proposed model show that the more risk-averse investor will invest more wealth in the risk-free security. They also show that the optimal invested amount in risky security increases as the risk-free return decreases and the optimal utility increases as the risk-free return increases, whereas the optimal utility increases as the transaction costs decrease. In most instances the utilities provided by the proposed two-stage model are larger than those provided by the single-stage model.

scholarly journals A Fast Learning Method for Accurate and Robust Lane Detection Using Two-Stage Feature Extraction with YOLO v3

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4308 ◽  
Author(s):  
Xiang Zhang ◽  
Wei Yang ◽  
Xiaolin Tang ◽  
Jie Liu
Keyword(s):  
Learning Algorithm ◽  
Structural Parameters ◽  
Feature Learning ◽  
Automatic Generation ◽  
Detection Algorithm ◽  
Lane Detection ◽  
Stage Model ◽  
Two Stage ◽  
Label Data ◽  
Second Stage

To improve the accuracy of lane detection in complex scenarios, an adaptive lane feature learning algorithm which can automatically learn the features of a lane in various scenarios is proposed. First, a two-stage learning network based on the YOLO v3 (You Only Look Once, v3) is constructed. The structural parameters of the YOLO v3 algorithm are modified to make it more suitable for lane detection. To improve the training efficiency, a method for automatic generation of the lane label images in a simple scenario, which provides label data for the training of the first-stage network, is proposed. Then, an adaptive edge detection algorithm based on the Canny operator is used to relocate the lane detected by the first-stage model. Furthermore, the unrecognized lanes are shielded to avoid interference in subsequent model training. Then, the images processed by the above method are used as label data for the training of the second-stage model. The experiment was carried out on the KITTI and Caltech datasets, and the results showed that the accuracy and speed of the second-stage model reached a high level.

Effect of Swirl on Gasification Characteristics in an Entrained-flow Coal Gasifier

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Rongbin Li ◽  
Mingzhuang Xie ◽  
Hui Jin ◽  
Liejin Guo ◽  
Fengqin Liu
Keyword(s):  
Coal Gasification ◽  
Three Dimensional ◽  
Reaction Model ◽  
Gas Temperature ◽  
Swirl Number ◽  
Entrained Flow ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Product Composition ◽  
Gas Efficiency

AbstractThe three-dimensional (3-D) comprehensive mathematical model was developed to simulate the coal gasification process in an entrained flow gasifier with a swirl burner. The models employed or developed includes the coal devolatilization model, the char combustion and gasification model, the gas homogeneous reaction model, the random-trajectory model, gas turbulence model, and the P-1 radiation model. The solution of models was executed based on the computational fluid dynamics (CFD). By qualitatively comparing the results at different swirl number, the significant influences of swirl on characteristics of coal gasification such as flow distributions, gas temperature and product composition including hydrogen (H2), carbon monoxide (CO), etc., and on the performance of coal gasification such as averaged exit product composition, carbon conversion rate and cold gas efficiency, were in detail discussed. Especially, a proper swirl number (S ≤ 0.65) in favor of gasification was found for the investigated gasifier in this paper.

HAEMODYNAMIC CONTRIBUTIONS TO THE PATHOGENESIS OF PREECLAMPSIA AND ECLAMPSIA

2008 ◽  
Vol 19 (1) ◽  
pp. 85-104 ◽  
Author(s):  
IRA M BERNSTEIN ◽  
MARILYN J CIPOLLA
Keyword(s):  
Endothelial Injury ◽  
Trophoblast Invasion ◽  
Stage Model ◽  
Abnormal Placentation ◽  
Two Stage ◽  
Second Stage

Current hypotheses regarding the origins of preeclampsia have focused on the “Two stage model”. This model suggests that the primary steps in the pathophysiologic sequence of preeclampsia are initiated by abnormal placentation including the classic finding of abnormal trophoblast invasion of maternal decidual spiral arteries. The second stage of the sequence includes the elaboration of a single or multiple substances from these disordered placentas which contribute to the generalized maternal systemic illness, eventually manifesting as endothelial injury, hypertension and proteinuria. Recent studies have focused on the role of pro and anti-angiogenic peptides as potential placentally derived aetiologic agents in this pathophysiologic sequence, although other placental products have been highlighted in recent research. Despite the fact that this modeling of preeclampsia has widespread support significant limitations to this hypothesis can be identified.

scholarly journals Evidence for a two-stage model of microbial infection

1968 ◽  
Vol 66 (2) ◽  
pp. 273-280 ◽  
Author(s):  
G. G. Meynell ◽  
Joan Maw
Keyword(s):  
Standard Error ◽  
Stage Model ◽  
Microbial Infection ◽  
Two Stage ◽  
Second Stage ◽  
Initial Stage ◽  
The Mean ◽  
Pass Through

SUMMARYColony counts on mice given the same number ofSalmonellaalways differ considerably. However, the standard error of the mean log count does not increase after the first 1·5 hr. of infection until the 8th or 10th day. These infections therefore appear to pass through an initial stage lasting a few hours, in which a varying proportion of the inoculum is killed, followed by a prolonged second stage in which the scatter in individual colony counts remains constant.

scholarly journals Co-Gasification Characteristics of Coal and Biomass Using CO2 Reactant under Thermodynamic Equilibrium Modelling

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7384
Author(s):  
M. Shahabuddin ◽  
Sankar Bhattacharya
Keyword(s):  
Steady State ◽  
Thermodynamic Equilibrium ◽  
Operating Conditions ◽  
Heating Value ◽  
Entrained Flow ◽  
Cold Gas Efficiency ◽  
Lower Heating Value ◽  
Entrained Flow Gasifier ◽  
Gas Efficiency ◽  
Increasing Temperature

This study assessed the entrained flow co-gasification characteristics of coal and biomass using thermodynamic equilibrium modelling. The model was validated against entrained flow gasifier data published in the literature. The gasification performance was evaluated under different operating conditions, such as equivalence ratio, temperature, pressure and coal to biomass ratio. It is observed that the lower heating value (LHV) and cold gas efficiency (CGE) increase with increasing temperature until the process reaches a steady state. The effect of pressure on syngas composition is dominant only at non-steady state conditions (<1100 °C). The variation in syngas composition is minor up to the blending of 50% biomass (PB50). However, the PB50 shows a higher LHV and CGE than pure coal by 12%and 18%, respectively. Overall, biomass blending of up to 50% favours gasification performance with an LHV of 12 MJ/kg and a CGE of 78%.

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