Gasification Of Petroleum Coke Research Articles

Greenhouse Gas Analysis for Hydrogen Fuel Cell Vehicles

Hydrogen can be produced from many feedstocks with different production and delivery pathways. Production options include conversion from a variety of feedstocks and energy sources. Delivery modes for vehicle fueling include compressed gas in tube trailers and pipelines, liquefied hydrogen in trucks, or on-site production. Alternative carrier options such as chemical hydrides are also being investigated. The energy inputs and greenhouse gas emissions (GHG) were analyzed for different production pathways for hydrogen fuel cell vehicles (FCVs) and comparable gasoline fueled vehicles. The results for on-site reforming of natural gas, central plant natural gas reforming, petroleum coke gasification, central plant biomass pyrolysis, and on-site electrolysis using a mix of natural gas based and renewable power are presented in this paper. Well to wheel energy inputs and GHG emissions were determined from primary energy inputs to the fuel cycle using analysis tools developed by TIAX, which account for the contribution of energy from natural gas, biomass, petroleum, and electric power.

The use of petroleum coke as fuel in chemical-looping combustion

Chemical-looping combustion is a novel technique used for CO2 separation that previously has been demonstrated for gaseous fuel. This work demonstrates the feasibility of using solid fuel (petroleum coke) in chemical-looping combustion (CLC). Here, the reaction between the oxygen carrier and solid fuel occurs via the gasification intermediates, primarily CO and H2. A laboratory fluidized-bed reactor system for solid fuel, simulating a CLC-system by exposing oxygen-carrying particles to alternating reducing and oxidizing conditions, has been developed. In each reducing period, 0.2 g of petroleum coke was added to 20 g of oxygen carrier composed of 60% active material of Fe2O3 and 40% inert MgAl2O4. The effect of steam and SO2 concentration in the fluidizing gas was investigated as well as effect of temperature. The rate of reaction was found to be highly dependent on the steam and SO2 concentration as well as the temperature. Also shown was that the presence of a metal oxide enhances the gasification of petroleum coke. A preliminary estimation of the oxygen carrier inventory needed in a real CLC system showed that it would be below 2000 kg/MWth.

Modeling reaction kinetics of petroleum coke gasification with CO 2

Kinetics characteristics of petroleum coke gasification with CO 2 at 1248–1323 K and 0.1 MPa were studied using a pressurized thermogravimetric analyzer (TGA). It is shown that gasification rate increases with increasing conversion and then decreases after reaching a peak value around x = 0.3. The poor initial porosity is the main reason of the occurrence of maximal gasification rate. A normal distribution function model was proposed to fit the kinetics data. Results show it can describe well the variation of gasification rate at different temperatures. Relationship between the parameter r m in the model and temperature T obeys to the Arrhenius law. Activation energy of petroleum coke CO 2 gasification is 198 kJ mol −1 and the reaction order is 0.54–0.88 in the investigated temperature range, which are in accordance with reported data.

Kinetic Modeling for the Combined Pyrolysis and Steam Gasification of Petroleum Coke and Experimental Determination of the Rate Constants by Dynamic Thermogravimetry in the 500−1520 K Range

The detailed kinetic mechanisms for the combined endothermic pyrolysis and steam gasification of petroleum coke are formulated using elementary chemisorption and reaction steps. The pyrolysis model is based on a linear combination of first-order decomposition rates of pseudo components. The gasification model is based on the oxygen-exchange mechanism describing reversible O-transfer surface reactions followed by a unidirectional gasification step, and on an extended mechanism describing, in addition, reversible steam sorption as OH/H groups and irreversible surface chemistry. The kinetic rate laws of Langmuir−Hinshelwood type are derived by assuming sorption equilibrium and by considering inhibition due to recombination of adsorbed oxygen and competition for active sites. The Arrhenius parameters of the rate constants for the pyrolysis and gasification of Flexicoke and Petrozuata Delayed coke are experimentally determined by dynamic thermogravimetric analyses with Ar, H2O, CO2, and H2O−CO2 mixtures in the...

Liquid-metal based coal gasification

Significant environmental benefits are secured in the gasification of coal, petroleum coke, biomass and similar carbonaceous materials, if the ash content is rendered non-leachable by the production of a vitreous slag. By combining float glass and generic melt circulation technologies, a new liquid-metal based process for gasification is proposed. The first case considered focuses on low sulphur feeds for which the proposed basic flowsheet involves a pressurised horizontal liquid-metal transport gasifier, to which solid charge materials are simply introduced onto the moving liquid metal surface via a barometric leg entrained in liquid metal. The solids are transported in a straight line through an air and steam top-blown zone to gasify the solids and produce a liquid sheet of molten slag, analogous to float glass manufacture, except that the liquid-metal is force circulated through the gasifier and external heat and mass transfer functions, involving direct countercurrent contacting in irrigated packed or moving beds to remove solid particulates and gaseous pollutants at high temperature. In the context of advanced power generation, the fuel gas is cooled to around 240°C to permit straightforward filtration and then is re-heated again by direct liquid-metal contacting to at least 730°C for transmission to the combustors of a gas turbine, which yields enhanced combined cycle efficiencies. More complex flow-sheets are then explored in which metallic zinc is added non-intrusively in a separate gas circuit independent of the fuel gas circuit to effect desulphurisation and to yield a valuable by-product, zinc sulphide. It is shown that not only can a slag be produced in a single stage air-blown cycle without the need for air separation and oxygen production, but also toxic components in air,in general, can be removed; in the particular case of mercury, this can be recovered directly in elemental form.

CO<sub>2</sub> Gasification of Petroleum Coke with Metal Hydroxide Catalysts

Gasification of petroleum coke with metal hydroxide catalysts has been carried out in CO2 at 850°C with a thermobalance. KOH is impregnated with coke, and Ca(OH)2 and fine particles of FeOOH are separately mixed with coke in water, metal loading being 3wt% in every case. Fixed carbon conversion excluding volatile matter was 7% and 55% after 120min without and with Fe, respectively, and it reaches 100% after 60min and 70min with K and Ca, respectively. Thus, K and Ca catalysts can promote the gasification remarkably. Initial rates per remaining carbon with K and Ca are as great as 50 and 100 times that without catalyst, respectively. The extent of rate enhancement by K addition is larger at the latter part of reaction, because the rate of K-catalyzed gasification increases exponentially with increasing fixed carbon conversion. When the samples after 50% conversion are subjected to X-ray diffraction measurements, the K is most highly dispersed among the three catalysts, and their presence lowers carbon crystallinity, irrespective of type of catalyst. Since inexpensive Ca(OH)2 is remarkably effective by simple mixing with coke in water, and is higher in thermal stability than KOH, which is known to vaporize readily as metal as the gasification proceeds, it can be concluded that the Ca is the most promising catalyst in coke gasification.

98/03764 Large rate enhancement by calcium catalysts in the gasification of petroleum coke

Isothermal gasification of petroleum coke with Ca(OH){sub 2} and CaCO{sub 3} has been carried out mainly under a high partial pressure of steam (80 kPa) with a thermobalance. These compounds, mixed with coke in water, increase the reaction rate, and CaCO{sub 3} shows almost the same catalytic activity as Ca(OH){sub 2} at the latter part of gasification. Fixed carbon conversion at 850 C without the Ca is 65 wt% after 2 h, whereas the catalysts achieve complete gasification within 1 h. The apparent activation energy is almost unchanged by Ca addition. H{sub 2} is the main product. The Ca increases H{sub 2} and CO{sub 2}, but it decreases CO, which leads to much higher H{sub 2}/CO ratio in the presence of the Ca. Thus, Ca(OH){sub 2} and CaCO{sub 3} promote shift reaction of CO formed with steam and are suitable for the production of H{sub 2}-rich gas from petroleum coke. (orig.)

98/02897 MTCI/ThermoChem steam reforming process for biomass: Mansour, M. N. et al. Proc. Biomass Conf. Am.: Energy, Environ., Agric. Ind., 2nd, 1995, 543–552

The design of a gasification plant includes the gasifier reactor as well as its auxiliary or support equipment. This chapter deals with the design of the gasifier reactor. Gasifiers are classified mainly on the basis of their gas–solid contacting mode and gasifying medium. Based on the gas–solid contacting mode, gasifiers are broadly divided into three principal types fixed or moving bed, fluidized bed, and entrained flow. One gasifier type is not necessarily suitable for the full range of gasifier capacities. There is an appropriate range of application for each. Entrained flow is the most successful and widely used gasifier type for largescale gasification of coal, petroleum coke, and refinery residues. It is ideally suited to most types of coal except low-rank coal, which, like lignite and biomass, is not attractive because of its large moisture content. High-ash coal is also less suitable because cold-gas efficiency decreases with increasing ash content. For slurry-fed coal, the economic limit is 20% ash; for dry feed it is 40%. The gasification temperature of an entrained-flow gasifier generally well exceeds 1000°C. This allows production of a gas that is nearly tar-free and has a very low methane content. A properly designed and operated entrained-flow gasifier can have a carbon conversion rate close to 100%. The product gas, being very hot, must be cooled in downstream heat exchangers that produce the superheated steam required for gasification.

98/01217 Large rate enhancement by calcium catalysts in the gasification of petroleum coke: Ohtsuka, Y. et al. DGMK Tagungsber., 1997, 9703 (Proceedings ICCS '97, Volume 2), 1245–1248

98/01217 Large rate enhancement by calcium catalysts in the gasification of petroleum coke: Ohtsuka, Y. et al. DGMK Tagungsber., 1997, 9703 (Proceedings ICCS '97, Volume 2), 1245–1248

97/00304 Prevention of ash component deposit on wall of gasifier in gasification of petroleum coke

97/00304 Prevention of ash component deposit on wall of gasifier in gasification of petroleum coke

97/00300 Method for gasification of petroleum coke with removal of heavy metals

97/00300 Method for gasification of petroleum coke with removal of heavy metals

The inorganic geochemistry of coal, petroleum, and their gasification/combustion products

The inorganic makeup of coal and petroleum differ in several crucial ways. The origins of these differences include the disparate geologic environments of formation, the contrasting parent materials (plant versus planktonic) and hence distinct organic species, and the physical state of the fuels (solid versus liquid). The inorganic chemistry of petroleum is usually controlled by the type and abundance of its organic compounds (i.e., V, Ni, ± Fe-bearing porphyrins and S-bearing thiols, sulfides, disulfides, thiophenic derivatives, resins, and asphaltenes), with significant, though often smaller contributions from entrained mineral phases. This near balance of inorganic compositional control causes petroleum to form combustion/gasification (pyrochemical) slag and ash with a large number of elements (i.e., V, Ni, S, Fe, Ca, Na, K, Mg, Si, and Al) in significant relative concentrations. This balance provides also opportunities for large departures from any given “norm”. The inorganic chemistry of coal, on the other hand, is dominantly controlled by its contained detrital and authigenic mineral matter, with relatively small contributions from organically carried elements other than sulfur. Detrital minerals are those that survive the geological processes of weathering and transport, and hence are a small group of physically resistant and chemically stable minerals including quartz, clay minerals, and oxides of Fe and Ti. The most abundant authigenic minerals in coal include clay minerals, pyrite/marcasite, carbonates, Ca- and Fe-sulfates, and Fe-oxides and hydroxides. Pyrochemical slag and ash from coal are therefore primarily enriched in Si, Al, Ca, Fe, and S. From a processing standpoint, the behavior of slag and fly ash is largely a function of the complexity of the fuel's inorganic chemistry (including the original mode of occurrence of the various elements), and the observed oxygen fugacity. Pyrochemical environments vary from reducing to oxidizing as a result of proximity to the flame and operational mode (combustion versus gasification). Consequently, multivalent elements further contribute to the complexity of slag/ash behavior by essentially behaving as separately unique elements when in their various valence states. In coal, the two abundant, multivalent inorganic elements are Fe (0, + 2, and +3) and S (−2, 0, +2, +4, and +6). In petroleum there are four abundant, multivalent inorganic elements: Ni (0 or +2), Fe (0, +2, and +3), V (+2, +3, +4, and +5), and S (−2, 0, +2, +4, and +6). The larger number of abundant inorganic elements in petroleum than coal, as well as the broader range of associated valence states, leads to more diverse slag/ash species formed during petroleum combustion/gasification, and consequently less predictable slag/ash behavior. A phase characterization of slags produced by the gasification of petroleum coke (a petroleum refining byproduct) illustrates their increased complexity with respect to typical coal slags.

Studies in catalytic steam gasification of petroleum coke with special reference to the effect of particle size

The object of this work is to study the effect of particle size, porosity, and thickness of a pellet on the gasification of very low ash (<0.5%) petroleum coke with steam both in the presence and absence of catalyst. Isothermal runs were carried out in the temperature range 695-880/sup 0/C using different sizes of particles (0.037-0.59 mm) and also different thicknesses of flat plates (0-7 mm) prepared from these particles. The experimental results showed some unusual behavior. The rate constant was observed to increase with an increase in particle size as well as with a decrease in thickness of the flat plates.