Hot Coke Oven Gas Research Articles

Large-eddy simulation of the non-adiabatic reforming process of hot coke oven gas using a flamelet-based approach

Large-eddy simulation of the non-adiabatic reforming process of hot coke oven gas using a flamelet-based approach

Prediction of hot coke oven gas reforming by LES coupled with the extended flamelet/progress variable approach

Large-eddy simulation (LES) coupled with the extended flamelet/progress variable approach (EFPV) has been performed to predict characteristics of reacting flows in a bench-scale hot coke oven gas (HCOG) reformer. In order to investigate the capability of capturing effects of operating conditions, simulations were carried out in two different cases in which the coke oven gas temperature and oxygen ratio were altered. Results showed that the LES coupled with the EFPV performed very well in terms of predicting temperature distribution as well as the temperature variation trend between the two cases. In addition, major species such as H2, CO, CO2, H2O and CH4, as well as minor species like benzene and some typical polycyclic aromatic hydrocarbons (PAH) were analyzed to illustrate their activities and dominant chemical events. With regards to the composition of the dry reformed gas, comparisons were made between the experimental data and the numerical simulation results, and reasonable results have been obtained. It has been confirmed that the general feature of the reacting flows in the HCOG reformer can be precisely captured by the present LES.

No.32 詳細反応速度モデル簡略化による石炭乾留ガス部分酸化改質炉内の反応性乱流解析

No.32 詳細反応速度モデル簡略化による石炭乾留ガス部分酸化改質炉内の反応性乱流解析

No.20 高温コークス炉ガス無触媒改質反応の詳細数値解析(熱分解・コークス(3))

No.20 高温コークス炉ガス無触媒改質反応の詳細数値解析(熱分解・コークス(3))

Study on Steam Reforming of Tar in Hot Coke Oven Gas for Hydrogen Production

Thermodynamic analysis and experiments of the steam reforming process of 1-methylnaphthalene as the tar model compound from coke oven gas (COG) were performed in this paper. In the thermodynamic analysis, as the temperature and steam/carbon (S/C) ratio rose, the hydrogen yield first increased and then flattened out yet with the compound completely converted and almost no coke deposition formed. In the experiments using a Ni/Mg catalyst with Ca12Al14O33 as a carrier, with the increases of the temperature and S/C ratio and the decrease of the methane-equivalent gas hourly space velocity (GC1HSV), the reforming result for hydrogen production became better gradually. After the temperature and S/C ratio increased to 800 °C and 12:1, respectively, and the GC1HSV decreased to 145 h–1, the hydrogen yield and carbon conversion could reach over 90% and 97%, respectively, even very close to the thermodynamic values. Additionally, the catalytic stability and resistance to coke formation of the used catalyst also impr...

A CFD study on the reacting flow of partially combusting hot coke oven gas in a bench-scale reformer

A computational fluid dynamics (CFD) approach to simulate reacting flow in a hot coke oven gas (HCOG) reformer is presented. The HCOG was reformed by non-catalytic partial oxidation in a tubular reactor (0.6m i.d. and ∼4.1m long) with four oxygen nozzles (0.0427m i.d.), which was installed on a platform of an operating coke oven. The reforming of HCOG, a multi-component mixture, in a turbulent flow was simulated numerically by considering both chemical reactions and fluid dynamics. The detailed chemical kinetic model, originally consisting of more than 2000 elementary reactions with 257 species, was reduced to 410 reactions with 47 species for realising a kinetic model of finite rate reactions with a k–ε turbulence model. The calculation was carried out using the eddy dissipation concept (EDC) coupled with the kinetic model, and accelerated using the in situ adaptive tabulation (ISAT) algorithm. Numerical simulations could reproduce the reformed gas compositions fairly well, such as H2, CO, CO2, and CH4, as well as the temperature profile in a HCOG reformer as measured by thermocouples.

Use of Waste Plastics in Coke Oven: A Review

To help in building a recycling-oriented sustainable society, Nippon Steel & Sumitomo Metal Corporation developed a waste plastic-recycling process using coke oven and put it into commercial operation in 2000. Now roughly 200,000 tons per year of waste plastics are processed in coke oven in Japan. In this process, the waste plastics collected from households are agglomerated to the sizes ranging from 20 to 30 mm in diameter and charged into coke ovens with coal at the blending ratio of about 1 mass%. Waste plastics are thermally decomposed into approximately 20 mass% coke, 40 mass% hydrocarbon oil (tar and light oil) and 40 mass% coke oven gas, which are utilized as iron ore-reducing agents in blast furnaces, raw materials for the chemical industry, and a fuel for power plants, respectively. Moreover, 92 mass% of the chlorine in waste plastics is released and absorbed by the ammonia liquor spray for cooling hot coke oven gas and converted to ammonium chloride. The waste plastic-recycling process using coke ovens is superior in that a large amount of waste plastics can be treated, useful materials can be recovered using the existing facilities, coke quality can be kept the same and the chlorine released from waste plastics can be fixed in the existing ammonia liquor spray system.

Predicting the temperature and reactant concentration profiles of reacting flow in the partial oxidation of hot coke oven gas using detailed chemistry and a one-dimensional flow model

A numerical approach is presented for predicting the species concentrations and temperature profiles of chemically reacting flow in the non-catalytic partial oxidation of hot coke oven gas (HCOG) in a pilot-scale reformer installed on an operating coke oven. A detailed chemical kinetic model consisting of 2216reactions with 257species ranging in size from the hydrogen radical to coronene was used to predict the chemistries of HCOG reforming and was coupled with a plug model and one-dimensional (1D) flow with axial diffusion model. The HCOG was a multi-component gas mixture derived from coal dry distillation, and was approximated with more than 40compounds: H2, CO, CO2, CH4, C2 hydrocarbons, H2O, aromatic hydrocarbons such as benzene and toluene, and polycyclic aromatic hydrocarbons up to coronene. The measured gas temperature profiles were reproduced successfully by solving the energy balance equation accounting for the heat change induced by chemical reactions and heat losses to the surroundings. The approach was evaluated critically by comparing the computed results with experimental data for exit products such as H2, CO, CO2, and CH4, in addition to the total exit gas flow rate. The axial diffusion model slightly improves the predictions of H2, CO, and CO2, but significantly improves those of CH4 and total exit flow rate. The improvements in the model predictions were due primarily to the improved temperature predictions by accounting for axial diffusion in the flow model.

No.31 反応熱と改質炉外壁からの放熱を考慮した石炭乾留ガス部分酸化改質反応の数値解析(研究発表)

No.31 反応熱と改質炉外壁からの放熱を考慮した石炭乾留ガス部分酸化改質反応の数値解析(研究発表)

Catalytic Reforming of Model Tar Compounds from Hot Coke Oven Gas over Pd Promoted Ni/Mg(Al)O Catalysts

Pd (0.1-1 wt%) loaded Ni/Mg(Al)O catalysts have been prepared by co-precipitation and impregnation methods, and their catalytic activities were tested in the catalytic reforming of tar components from hot coke oven gas (COG) with lower steam/carbon (S/C) molar ratio. The 0.5%Pd-12%Ni/Mg3(Al)O bimetallic catalyst derived from hydrotalcite showed excellent catalytic activity. The effect of reaction temperature on the catalytic performance was investigated in detail. Toluene could be completely converted into small gas molecules of CH4, CO and CO2 over the catalyst at S/C=0.42 and 600°C under atmospheric pressure.

Catalytic Reforming of Model Tar Compounds from Hot Coke Oven Gas for Light Fuel Gases Production over Bimetallic Catalysts

The catalytic reforming of toluene was performed to investigate the possibility for directly converting tar components from hot coke oven gas (COG) with lower steam/carbon (S/C) molar ratio to light fuel gases. The Ni0.25Me0.25/Mg2.5(Al)O (Me=Fe, Cu, Zn, Mn) bimetallic catalysts derived from hydrotalcite showed excellent catalytic activity. The effects of various reaction conditions on the catalytic performance were investigated in detail. Toluene could be completely converted into small gas molecules of CH4, CO and CO2 over the catalyst at S/C=0.7 and 650-750 oC under atmospheric pressure. Lower reaction temperature and higher H2 content in feed gas both could promote the formation of CH4, while higher S/C molar ratio benefited the CO yield.

Application of an Existing Detailed Chemical Kinetic Model to a Practical System of Hot Coke Oven Gas Reforming by Noncatalytic Partial Oxidation

For more efficient utilization of coke oven gas (COG), a byproduct from the production of metallurgical cokes, a reforming technology of hot COG (HCOG) was developed to obtain material gases suitable for methanol production. A test plant was installed on a platform of an operating coke oven. HCOG was fed into a tubular reactor (0.6 m i.d. and 3.2 m long) at flow rates from 28 to 103 Nm3/h and was partially oxidized by injecting O2 (from 12 to 30 Nm3/h) from nozzles near the inlet. Exhaustive test runs identified the appropriate reforming conditions required to achieve more than 2.2-fold syngas amplifications, and the optimum product gas composition for methanol synthesis. Numerical simulations using detailed chemical kinetics coupled with a plug-flow reactor model were also conducted. The kinetic model developed by Richter and Howard [Phys. Chem. Chem. Phys. 2002, 4, 2038−2055] including 257 chemical species and 2216 elementary steplike reactions was used. HCOG was modeled as a multicomponent gas mixture involving H2, CO, CO2, CH4, C2 hydrocarbons, H2O, and 31 aromatic hydrocarbons such as benzene and toluene, as well as polycyclic aromatic hydrocarbons up to coronene, to represent the HCOG tar. Satisfactory agreement was observed in comparisons between the predictions from the numerical simulations and the data measured from the 20 test runs, indicating that the model can be a promising tool toward designing a demonstration/commercial HCOG reforming plant.

Catalytic Conversion of Tar Components from Hot Coke Oven Gas over Ni/MgAl(O) Catalyst

Catalytic Conversion of Tar Components from Hot Coke Oven Gas over Ni/MgAl(O) Catalyst

Catalytic reforming of model tar compounds from hot coke oven gas with low steam/carbon ratio over Ni/MgO–Al 2O 3 catalysts

The catalytic reforming of toluene and naphthalene was performed to investigate the possibility for directly converting tar components from hot coke oven gas (COG) with lower steam/carbon (S/C) molar ratios to light fuel gases. The NiO/MgO–Al 2O 3 catalysts reduced exhibited excellent catalytic activity, stability and sulphur tolerance. The effects of various reaction conditions and S/C ratios on the catalytic performance were investigated in detail. Toluene and naphthalene were completely converted into small gas molecules at 700–800 °C and S/C = 0.28. An appropriate amount of steam benefited the methanation reaction of CO and H 2. The effects of N 2, CH 4 or CO in COG were also discussed. Relative to N 2, CO contributed to the conversion of toluene and the formation of CH 4, but the opposite was true for CH 4. The sulphur tolerance was tested by adding H 2S in the feed gas. The reaction results were explained by a water cycle mechanism.

Catalytic conversion of tar from hot coke oven gas using 1-methylnaphthalene as a tar model compound

High concentration (1.3vol.%) of 1-methylnaphthalene was selected as a tar model compound to investigate the catalytic conversion of tar from hot coke oven gas (COG) with lower steam content under atmospheric pressure over the Ni/MgO/Al2O3 catalysts. The catalysts were prepared by impregnating boehmite (AlOOH) with an aqueous solution of magnesium nitrate and nickel nitrate. The effects of Ni loading, reaction temperature, steam/carbon (S/C) molar ratio on the catalytic performance of the catalysts were discussed in detail. The catalysts exhibited excellent activity, stability and resistance to carbon deposition. Tar compounds could be completely converted into light fuel gases over 10% Ni/MgO/Al2O3 at 775°C and S/C=0.7. The effect experiments of sulphur were performed by adding 1000 and 2500ppm H2S in the feed. The used catalysts were characterized by XRD and TG analyses. It was first found that addition of H2S in the feed could greatly inhibit the carbon formation on the catalyst surface and lead to significant improvement in the activity and stability of the catalyst. This phenomenon has never been reported previously in the tar steam reforming.

Numerical Simulation of the Partial Oxidation of Hot Coke Oven Gas with a Detailed Chemical Kinetic Model†

The non-catalytic partial oxidation of hot coke oven gas (HCOG) was numerically simulated using a detailed chemical kinetic model and a completely mixed batch reactor model. The kinetic model was primarily based on that developed by Richter and Howard [Phys. Chem. Chem. Phys. 2002, 4 (11), 2038−2055], including more than 200 chemical species and more than 2000 elementary-step-like reactions. The HCOG was modeled as a multi-component gas mixture involving H2, CO, CO2, CH4, C2 hydrocarbons, H2O, and 31 aromatic hydrocarbons, such as benzene and toluene, as well as polycyclic aromatic hydrocarbons up to coronene, to represent the HCOG tar. The effect of oxygen addition in the inlet gas mixture was investigated at oxygen concentrations from 0 to 15 vol %. The simulations indicated that oxygen was consumed almost completely for the combustion of reactive light gases, such as H2 and CO, and light hydrocarbons, such as CH4 and C2H6, within a reaction time of a few tens of milliseconds when the inlet gas temperature was 1173 K. In reforming the tar involved in HCOG, the primary role of oxygen should be to induce temperature increases of the reacting gas by combustion, thereby accelerating the subsequent reforming of the tar by steam. A reaction pathway analysis suggested that the co-existence of oxygen and aromatic hydrocarbon radicals was necessary to decompose aromatic compounds into compounds of lower molecular mass.

Partial oxidation of simulated hot coke oven gas to syngas over Ru-Ni/Mg(Al)O catalyst in a ceramic membrane reactor

Hydrogen amplification from simulated hot coke oven gas (HCOG) was investigated in a BaCo 0.7Fe 0.2Nb 0.1O 3-δ (BCFNO) membrane reactor combined with a Ru-Ni/Mg(Al)O catalyst by the partial oxidation of hydrocarbon compounds under atmospheric pressure. Under optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 13.3 ml/(cm 2·min). By reforming of the toluene and methane, the amount of H 2 in the reaction effluent gas was about 2 times more than that of original H 2 in simulated HCOG. The Ru-Ni/Mg(Al)O catalyst used in the membrane reactor possessed good catalytic activity and resistance to coking. After the activity test, a small amount of whisker carbon was observed on the used catalyst, and most of them could be removed in the hydrogen-rich atmosphere, implying that the carbon deposition formed on the catalyst might be a reversible process.

Hydrocracking of Tar Components from Hot Coke Oven Gas over a Ni/Ce-ZrO2/γ-Al2O3 Catalyst at Atmospheric Pressure

Abstract Ni/Ce-ZrO 2 /γ-Al 2 O 3 catalysts with different Ce-ZrO 2 contents and Ni loadings were prepared by a two step impregnation method and characterized by X-ray diffraction, transmission electron microscopy, N 2 adsorption, and temperature-programmed reduction. The catalysts were used for the hydrocracking of toluene and naphthalene, which were model tar compounds in hot coke oven gas, under atmospheric pressure at 800 °C. They showed excellent catalytic activity, stability, and some sulfur tolerance. Both toluene and naphthalene was converted into light fuel gases even at a low mole ratio of steam to carbon (S/C = 0.44). During the testing period of 7 h, no coke deposition was observed on the surface of the catalysts. The results indicated that the addition of Ce-ZrO 2 limited the sintering of Ni particles and enhanced the catalytic activity. The Ni/Ce-ZrO 2 /γ-Al 2 O 3 catalyst is promising for the direct removal of tar compounds in hot coke oven gas with low S/C ratios.

Hydrogen production from simulated hot coke oven gas by catalytic reforming over Ni/Mg(Al)O catalysts

Hydrogen production by catalytic reforming of simulated hot coke oven gas (HCOG) with toluene as a model tar compound was investigated in a fixed bed reactor over Ni/Mg(Al)O catalysts. The catalysts were prepared by a homogeneous precipitation method using urea hydrolysis and characterized by ICP, BET, XRD, TPR, TEM and TG. XRD showed that the hydrotalcite type precursor after calcination formed (Ni, Mg)Al 2O 4 spinel and Ni-Mg-O solid solution structure. TPR results suggested that the increase in Ni/Mg molar ratio gave rise to the decrease in the reduction temperature of Ni 2+ to Ni 0 on Ni/Mg(Al)O catalysts. The reaction results indicated that toluene and CH 4 could completely be converted to H 2 and CO in the catalytic reforming of the simulated HCOG under atmospheric pressure and the amount of H 2 in the reaction effluent gas was about 4 times more than that in original HCOG. The catalysts with lower Ni/Mg molar ratio showed better catalytic activity and resistance to coking, which may become promising catalysts in the catalytic reforming of HCOG.

Hydrogen Production by Reforming of Simulated Hot Coke Oven Gas over Nickel Catalysts Promoted with Lanthanum and Cerium in a Membrane Reactor

Catalysts of Ni/Mg(Al)O promoted with lanthanum and cerium were tested in a BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) membrane reactor by catalytic partial oxidation of simulated hot coke oven gas (COG) with toluene as a model tar compound under atmospheric pressure. Analysis of the catalysts suggested that the hydrotalcite precursor after thermal treatment lead to a good dispersion of nickel forming the solid solution NiO−MgO and spinel (Ni,Mg)Al2O4. The promoted catalysts had higher oxygen permeation flux, better catalytic activity, and better resistance to carbon formation, which will be promising catalysts in the catalytic partial oxidation reforming of hot COG.