Desulfurization Of Coke Oven Gas Research Articles

Efficiency, Economic, Energy, and Safety (3ES) Analyses on Different Configurations of MDEA Absorption Process for Coke Oven Gas Desulfurization

The purification of Coke Oven Gas received great attention due to its high potential of utilization for power generation and hydrogen production. This study simulated different configuration of MDEA process flowsheet and implemented the comprehensive evaluation. The comprehensive evaluation included H2S removal efficiency, energy consumption, techno-economic analysis, and safety assessment. The modified MDEA processes applied additional flash drums to enhance H2S removal efficiency and reduce heat duty of distillation column reboiler. MDEA with two intermediate flash drums showed the highest efficiency (96.5%), lowest reboiler duty (6.27 MW), and the lowest operation cost ($ 50/ Nm3-y). Conventional MDEA process exhibited the lowest capital cost ($ 1.531 million) and H2S leakage amount (30.3 kg) for an accident. MDEA with two flash drums process can be recommended when high purity coke oven gas was required. Conventional MDEA was recommended to consider safety and short-term operation with the lowest capital cost. MDEA with one flash drum can be recommended for stable desulfurization operation.

Ionic liquid screening for desulfurization of coke oven gas based on COSMO-SAC model and process simulation

1305 ionic liquids (ILs) involving 45 cations and 29 anions were computationally screened to search the optimal solvents for deep desulfurization of coke oven gas (COG) based on the combination of the COSMO-SAC model and process simulations. Firstly, the molecular structures, including those of independent ions and solutes, were constructed and geometrically optimized using density functional theory (DFT) calculation with the VWN-BP functional of generalized gradient approximation (GGA) and DNP basis set (v4.0) in DMol3 software. The σ-profiles of ion pairs for COSMO-SAC model were calculated through summation of σ-profiles of cations and anions. Secondly, Henry’s constant of various gas solutes such as H2S, COS, TS, CH4 in each ion pair was estimated by COSMO-SAC model. In order to balance the trade-off between the solubility and selectivity of various sulfides in ionic liquids, the mass-based Absorption-Selectivity-Desorption index (ASDI) combined with physical properties was employed as the evaluation metrics. Four ILs with high values of ASDI and appropriate melting point and viscosity were screened out for further process simulation. Finally, sensitivity analysis and central composite experimental design were performed to optimize the input parameters of process simulations on COG desulfurization, while total annual cost and specific energy consumption of the desulfurization processes were used to evaluate the economic and energy efficiency of various ILs. It is indicated that [C1mpyr][Oac] exhibits the high total sulfur removal ratio of 99.05% and the CH4 recovery ratio of 94.65%. In addition, its specific energy consumption and total annual cost were 5kWh/kg Sulfides and $9 million/year, respectively. In short, we proposed the combined COSMO-SAC and process simulation method that provide a comprehensive perspective of large-scale IL design for COG or similar gas mixture desulfurization.

Sulfint – the Czech gas desulfurization technology

The article describes one of the gas desulphurisation technologies which has been developed in the Czech Republic. The technology uses washing solution of organic complexes of various metals to remove H2S from gases. H2S removal is realized by its reaction with complexes of suitable metals with organic reagents. This leads to the H2S oxidation to elemental sulfur and the reduction of the metal protected by the organic complex to a lower oxidation state, which is also bound in the organic complex. Regeneration of the washing solution is performed by oxidation of the reduced form of the complex using oxygen from the air. Complexes of iron with ethylenediaminetetraacetic acid, nitrile triacetic acid or diethylenetriaminopentaacetic acid are used for the preparation of washing solutions. The reaction of the ferric complex of ethylenediaminetetraacetic acid with H2S is accompanied by a change in the color of the washing solution from a deep red color (like red wine) to a light brown color (like coffee with milk) of the ferrous complex of ethylenediaminetetraacetic acid. When this complex is completely depleted, it begins to decompose to black ferrous sulfide by further contact with H2S. This reaction is irreversible. The ferrous complex of ethylenediaminetetraacetic acid can be regenerated by reaction with oxygen, which also takes place at normal or elevated temperatures. The rate of this reaction is much slower compared to the reaction of H2S with the ferric complex. The process was discovered and intensively researched at the Institute for Fuel Research in Prague and later also at the University of Chemistry and Technology Prague. The first pilot plant tests took place with the desulfurization of coke oven gas at the Coking Plant Vítězný únor in Ostrava, where the first operating facility working with the given technology was later built. Another operating facility working with this technology was put into operation at the Antonín Zápotocký High pressure gasification plant in Ústí nad Labem and was used for desulphurization of expansion gases from pressure purification of waste gas of the Rectisol system. The technology was named Sulfint. Both facilities operated successfully until the end of operation of the town-gas supply system in the Czech Republic in the mid-1990s.

A high efficient absorbent for the separation of H2S from low partial pressure coke oven gas.

To high efficiently remove H2S from low partial pressure coke oven gas (COG), a novel activator (tetramethylammonium arginine, [N1111][Arg]) was used to blend with N-methyldiethanolamine (MDEA) for the absorption of H2S. High concentrated [N1111][Arg]-MDEA aqueous solution was used as absorbent. Thermodynamic properties including absorption amount and H2S loading values were measured, then the kinetic apparent absorption rate was calculated based on the change of absorption amount with time. The removal efficiency of H2S in simulated COG was verified in tray towers. Compared with monoethanolamine (MEA)-MDEA and tetramethylammonium glycinate ([N1111][Gly])-MDEA aqueous solutions, [N1111][Arg]-MDEA aqueous solution takes advantages of higher absorption capacity, absorption rate and removal efficiency. Our results showed that the proposed absorbent has good industrial application prospect in coke oven gas desulfurization, because it achieved 100% removal of H2S in the tray tower containing only 4 sieve plates under high concentrated condition (water content < 45%), which may significantly decrease the energy consumption.

ОТРИМАННЯ ВОДНО-ОЛИВНИХ ЕМУЛЬСІЙ З ВІДХОДІВ І СУПУТНІХ ПРОДУКТІВ КОКСОХІМІЧНОГО ВИРОБНИЦТВА ПрАТ «ЮЖКОКС» ДЛЯ ПОДАЧІ В КАМ’ЯНОВУГІЛЬНУ ШИХТУ

The existing experience and results of previous studies for the production of emulsions from resinous waste and by-products of coke production has been analyzed. A necessary condition for the creation of stable emulsion is the presence in its composition of three main components: diluent oil, emulsifiers and a neutralizing agent. In order to determine the suitability of waste and by-products of production of PJSC "YUZHKOKS" as components of water-oil emulsions, the physicochemical characteristics of acid tar of ammonia capture, neutralized acid tar of rectification of crude benzene, resins and oils of biochemical plant, non-boiling residues of monoethanolamine desulfurization of coke oven gas, alkaline water, storage waste and coal tar has been studied. The ability of these materials to mix with each other has been also studied. As a result of research, it has been found that the presents of coal tar in the composition of the diluent oil leads to the formation of more stable over time emulsions with low viscosity. The amount of coal tar in diluent oils should be 50-70 %. Non-boiling residues of monoethanolamine purification of coke oven gas from hydrogen sulfide proved to be a better neutralizing agent than alkaline water, in particular, for the reason that in some cases their use allowed to obtain homogeneous mixtures without delamination and separation of the aqueous layer by mixing emulsion components. It has been shown that when emulsions preparing it is important to follow the order of mixing the components. Based on the obtained data, formulations have been developed and the conditions for obtaining stable emulsions has been determined. Recommendations for obtaining emulsions for the purpose of their qualified use by feeding to the coal blend and improving the operation of the existing plant for waste and by-products utilization at the enterprise has been formulated.

Thermodynamics of Hydrogen-Sulfide Conversion in a Claus Reactor in Coke-Oven Gas Desulfurization Circuit of MMK

For the Claus reactor of byproduct-capture shop 2 in the coke plant at PAO Magnitogorskii Metallurgicheskii Kombinat (MMK), thermodynamic calculation of the equilibrium hydrogen-sulfide conversion at 200–350°C is undertaken, in the following conditions: total mixture pressure 1.3 atm (130 kPa); initial Claus ratio CR = [H2S]/[SO2] = 1.5–10.0; initial hydrogen-sulfide concentration [H2S] = 0.3–6.5 vol %. When [H2S] ~ 1 vol %, the direction of equilibrium conversion is reversed. Accordingly, it is expedient to limit the number of catalytic stages in the processing of hydrogen sulfide on the basis of its initial concentration. In selecting the catalyst in the Claus reactor, it is expedient to take account of the characteristics of the gas being processed and to lower the Claus ratio to the working value CR ≤ 2.

Optimization of Coke Oven Gas Desulfurization and Combined Cycle Power Plant Electricity Generation

Many steel refineries generate significant quantities of coke oven gas (COG), which is in some cases used only to generate low pressure steam and small amounts of electric power. In order to improve energy efficiency and reduce net greenhouse gas emissions, a combined cycle power plant (CCPP) where COG is used as fuel is proposed. However, desulfurization is necessary before the COG can be used as a fuel input for a CCPP. Using a local steel refinery as a case study, a proposed desulfurization process is designed to limit the H2S content in COG to less than 1 ppmv, and simulated using ProMax. In addition, the proposed CCPP plant is simulated in Aspen Plus and is optimized using GAMS to global optimality with net present value as the objective function. Furthermore, the carbon tax is considered in this study. The optimized CCPP plant was observed to generate more than twice the electrical efficiency when compared to the status quo for the existing steel refinery. Thus, by generating more electricity within...

Solid-liquid phase equilibria of ternary system Na2S2O3-Na2SO4-H2O in a wide range of temperatures: Measurement and application

Abstract In order to provide a fundamental basis for treatment of wastewater from desulfurization of coke oven gas to recover pure salt, solid-liquid equilibrium data of Na2S2O3-Na2SO4-H2O system at T = (278.15, 283.15, 291.15, 333.15 or 353.15) K were measured. The experimental data was obtained using the isothermal solution saturation method and Schreinemaker’s wet residue method. The solid-liquid phase diagrams of the ternary system were constructed. The ternary phase diagrams turned out to be simple eutectic type containing one invariant point, two univariant curves, and two single-salt crystallization regions. It was found that the crystallization region of Na2SO4 is larger than that of Na2S2O3 and expands with the increasing of temperature. But the crystallization region of Na2S2O3 decreases with the increasing of temperature. Through analyzing the thermodynamic characteristics of Na2S2O3 and Na2SO4, two crystallization methods for separating the mixture of Na2S2O3-Na2SO4 were put forward. A simple comparison of the two crystallization methods was carried out.

Effectiveness of the Desulfurization of Coke-Oven Gas at PAO Magnitogorskii Metallurgicheskii Kombinat

To assess the capabilities of the desulfurization system for coke-oven gas in coking-product recovery shop 2 at PAO Magnitogorskii Metallurgicheskii Kombinat (MMK), the effectiveness of all stages in sulfur recovery unit (SRU) at the shop is analyzed. It is found that the capacity for catalytic conversion of hydrogen sulfide to sulfur is not being fully utilized. Its use would raise the temperature of both stages in the SRU’s R-6201 Claus reactor. The optimum temperature of the second catalytic stage of the R-6201/2 unit and maximum conversion to sulfur cannot be achieved because of the insufficient heat-exchanger efficiency resulting from surface deposits of sulfur. Observations at waste-heat boiler 1 of the elemental-sulfur production department in the copper plant of Norilsk Nickel’s Transpolar Division show that sulfur condensation on the heatexchanger surface decreases the heat transfer in the waste-heat boiler by 20–40%. Modification of the heating system for the second stage of the R-6201 Claus reactor in coking-product recovery shop 2 at PAO MMK by introducing a regulated bypass line is proposed.

Sulfidation and regeneration of iron-based sorbents supported on activated-chars prepared by pressurized impregnation for coke oven gas desulfurization

The sulfidation and regeneration properties of lignite char-supported iron-based sorbent for coke oven gas (COG) desulfurization prepared by mechanical stirring (MS), ultrasonic assisted impregnation (UAI), and high pressure impregnation (HPI) were investigated in a fixed-bed reactor. During desulfurization, the effects of process parameters on sulfidation properties were studied systematically. The physical and chemical properties of the sorbents were analyzed by X-ray diffraction (XRD), scanning electron microscope coupled with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared (FTIR) and BET surface area analysis. The results of desulfurization experiments showed that high pressure impregnation (HPI) enhanced the sulfidation properties of the sorbents at the breakthrough time for char-supported iron sorbents. HPI method also increased the surface area and pore volume of sorbents. Sulfur capacity of sorbents was enhanced with increasing sulfidation temperatures and reached its maximum value at 400 °C. It was observed that the presence of steam in coke oven gas can inhibit the desulfurization performance of sorbent. SO2 regeneration of sorbent resulted in formation of elemental sulfur. HPIF10 sorbent showed good stability during sulfide-regeneration cycles without changing its performance significantly.

Catalysts for the desulfurization of coke-oven gas

Two promising catalysts are tested in the desulfurization of coke-oven gas at OAO Magnitogorskii Metallurgicheskii Kombinat in a pilot plant (with a gas flow rate of up to 0.78 m3/h): AOK-78-57 titaniumoxide catalyst (produced by OOO Katalizator, Novosibirsk); and VA-2 vanadium catalyst on an aluminumoxide substrate (developed at the Institute of Catalysis, Siberian Branch, Russian Academy of Sciences and produced by OOO Novomichurinskii Katalizatornyi Zavod). The VA-2 catalyst shows some benefits in the conversion of hydrogen sulfide, with practically the same activity in the conversion of organosulfur components (CS2 and COS). With a final temperature of 450°C, CS2 conversion at VA-2 catalyst exceeds 99.5%, on average. Accordingly, VA-2 catalyst is promising for use in the first stages of catalytic conversion in sulfurremoval units of Claus type, including those for the desulfurization of coke-oven gas.

Regeneration of Fe–Zn–Cu Sorbents Supported on Activated Lignite Char for the Desulfurization of Coke Oven Gas

In this paper, the regeneration characteristics of activated-char-supported Fe–Zn–Cu sorbents were studied. The desulfurization and regeneration experiments were carried out using a quartz fixed-bed reactor at ambient pressure. The effects of regeneration conditions, such as space velocity, temperature, and steam concentration, on the regeneration performance were examined. The crystal phase, chemical structure of activated components, and physical structure of sorbents before and after regeneration were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) surface area. The experimental results indicated that the char-supported Fe–Zn–Cu sorbents can be regenerated at temperatures above 500 °C. The optimal regeneration parameters with a space velocity of 5000 h–1, temperature of 700 °C, and steam concentration of 50 vol % have been obtained. The result of regener...

Sulfidation Behavior of Fe-Zn Sorbents Supported on Lignite Char during Coke Oven Gas Desulfurization

Lignite char supported Fe-Zn sorbents were prepared by means of impregnation of Fe and Zn into coal followed by steam gasification. The sulfidation experiments were carried out using a fixed-bed quartz reactor in the temperature range of 473 to 673 K using simulated coke oven gas with a gas space velocity of 1,000 h–1. Strcuture changes of sorbents during sulfidation were analyzed using X-ray diffraction and scanning electron microscopy. The results show that the sorbents can remove both H2S and coke oven gas from the simulated coke oven gas with high efficiency, and the desulfurization efficiency increased with increasing metal loading level.

Intensification of sulfur extraction from the working solutions in the oxidative desulfurization of coke-oven gas

A deficiency of the oxidative removal of hydrocarbons from coke-oven gas is the insufficient extraction of elementary sulfur from the absorbing solution; the sulfur is formed by the oxidation of H2S. Sulfur buildup in the working solution interferes with the process and calls for periodic purification of the apparatus. To improve the extraction of sulfur from the solution, structural improvements are proposed. An inexpensive remedy is to supply surfactant so as to improve sulfur flotation. In this research, the surfactant used for wetting and flotation of the sulfur is analyzed. Classification of the reagents in terms of their hydrophilic properties is considered. Industrial samples of reagents intended to improve flotation are tested. The ascent and descent of sulfur particles in surfactant solutions is studied; the limiting wetting angle between the liquid drop and the solid surface of the sulfur particle is measured. Dynamic research on the flotation of sulfur particles by air bubbles is undertaken. The selected reagent is very effective in dynamic conditions, since the hydrophobic properties are maximized in the flotation process.

Desulfurization of coke oven gas using char-supported Fe-Zn-Mo catalysts: Mechanisms and thermodynamics

Sulfidation properties of char-supported Fe-Zn-Mo sorbents prepared by ultrasonic impregnation method were investigated during simultaneous removal of H2S and COS from coke oven gas (COG) using a fixed-bed quartz reactor. Sorbent samples before and after sulfidation were analyzed using X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The experimental results showed that the addition of Mo significantly improved the desulfurization properties (i.e., breakthrough time, sulfur capacity and desulfurization efficiency) of Fe-Zn sorbents. Desulfurization reactions were exothermic and thermodynamically favorable in the temperature range of 200–400 °C. Thermodynamic analysis of the sorbents indicated that higher concentration of H2S and lower concentration of H2 favors the reaction of metal oxides with H2S to form metal sulfides.

Emissions at Coke Plants: European Environmental Regulations and Measures for Emission Control

At coke plants several pollutants are formed during coking, which are released to ambient air. To protect human health and to avoid harmful impacts on ambient air quality effective control of coke oven emissions is most significant. At coke plants the main source of emissions of NOx, SO2 and particulate matter is the flue gas from combustion of cleaned coke oven gas in the battery underfiring. Hence, advanced processes for coke oven gas cleaning in the by-product plant, like scrubbing processes for desulfurization of coke oven gas, are important measures at coke plants to reduce emissions to air. Effective filter equipments are available to abate emissions of dust from coke pushing and coal charging. Fugitive emissions at the batteries from leaking oven doors, lids and ascension pipes as well as fugitive emissions in the by-product plant from leaking pipes, flanges and valves can be abated by effective sealings, smooth operation and regular maintenance of all equipments. Inside the European Union emissions at coke plants are regulated in EU-directives on basis of Best Available Techniques (BAT) and monitored regularly by stipulation of national and local authorities. This paper focuses on (1) Legal EU-regulations on abatement of coke oven emissions into air, (2) Modern emission control measures available nowadays at coke plants.

Aging of aluminum-oxide catalyst in the claus reactor during desulfurization of coke-oven gas

The activity of CR-31 aluminum-oxide catalyst (La Roche Chemicals) over a period of 6.5 years (2000–2007) in the Claus reactor of byproduct-trapping shop 2 is monitored within the coke plant at OAO Magnitogorskii Metallurgicheskii Kombinat. The rate and extent of irreversible deactivation of the aluminum-oxide catalyst due to hydrothermal aging are found to be fundamentally different in the conversion of hydrogen sulfide than in the conversion of carbonyl sulfide. It is expedient to use different catalysts in different stages of sulfur extraction: in the first stage, the catalyst should be optimized for the conversion of organosulfur compounds; in the second stage, the best choice is a traditional aluminum-oxide catalyst for the Claus conversion of hydrogen sulfide.

Purification of waste gases in the desulfurization of coke-oven gas

The operation of equipment for the hydrolysis of waste gases from the desulfurization of coke-oven gas is analyzed on the basis of chromatographic data. Specifically, the data relate to the operation of such equipment in shop 2 for trapping coking byproducts at OAO Magnitogorskii Metallurgicheskii Kombinat, over a period of four years (2004–2008). The reduced efficiency of the system in the third year of operation is due to sharp deactivation of the CR-31 aluminum-oxide catalyst (La Roche Chemicals) in the R-6301 reactor on account of sulfate formation on opening the reactor. In normal operation, the life of the catalyst in the R-6301 reactor is at least 2–3 years. To restore the efficiency of hydrolysis, the catalyst in the R-6301 reactor must be completely replaced, preferably with a specialized catalyst for hydrolysis and hydrogenation.

Frequency-phase characteristics of the automatic control system for the desulfurization of coke-oven gas at OAO MMK

Fourier analysis of the response function illuminates the frequency-phase characteristics of the automatic control system for sulfur extraction from coke-oven gas at OAO MMK, with an ADA-900 photometric gas analyzer. The control system based on the ADA-900 instrument tolerates external perturbations of the input parameters with a characteristic period no less than ∼10 min. This indicates the limits on the applicability of the instrument in the control systems of Claus equipment.

Operational experience with the automatic control system for the desulfurization of coke-oven gas at OAO Magnitogorskii Metallurgicheskii Kombinat

Operational experience with the automatic control system for the desulfurization of coke-oven gas at OAO Magnitogorskii Metallurgicheskii Kombinat is considered. This system was designed by Krupp-Koppers. Problems with the control system are analyzed—in particular, problems typical of control systems with feedback and photometric instruments. In practice, perturbation-based automatic control systems are more likely to ensure reliable and stable operation of the desulfurization system, if the operator periodically corrects the parameters in the control algorithm on the basis of independent monitoring of the process.