Coal liquefaction design

Costs based on plant processing 26,105 Mg/d (28,776 US ton/d) of Ilbnois No. 6 coal. Source Direct Coal Liquefaction Baseline Design and Systems Analysis, prepared by Bechtel and Amoco under DOE contract no. DE-AC22-90PC89857, March 1993. 

E. Gorin, C. J. Kulik, and H. E. Lebowitz, "Deashing of Coal Liquefaction Products Via Partial Deasphalting. 2. Hydrogenation and Hydro extract ion EffluentsINEC Process Design and Developments, Vol. 16, Jan. 1977. 

Aspects of coal liquefaction have been much researched, particularly with the re-emeigence of interest caused by the oil crisis in the 1970 s. The type of reactors used in the studies has been various, ranging from small bomb type microautoclaves through larger autoclaves and bench-scale reactors to larger scale pilot or demonstration plants. The use of differently sized and designed high pressure equipment for liquefaction studies further complicates an already complex system and allows only limited comparison of results. 

Autoclaves provide reactors which can be used readily to acquire data from coal liquefaction studies but are less representative of likely commercial plant tyi reactors than small scale continuous bed-type reactors. Ideally comparisons between reactors are best made by carrying out experiments in various designs of reactors under similar reaction conditions, but, in order to cover the full range of designs adequately, a larger expenditure on equipment (beyond the budgets of most laboratories) would be necessary. However, steps can be taken to cover the... 

All the hydrocracking/hydrogenation experiments were carried out in 500 ml capacity spinning type autoclaves. Two autoclaves of this design were used and the autoclaves were compared in experiments using the model compound phenanthrene, chosen because phenanthrene and its hydro-derivatives represent a large proportion of the solvent which is recycled in coal liquefaction processes. 

The difficulty in the recovery of catalysts from unreacted coal and minerals and the poor regenerability of used catalysts forces one to use disposable catalysts, especially in the primary stage. This increases the cost of coal liquefaction considerably. This section reviews the mechanism of catalyst deactivation, design of recoverable catalysts in the primary stage, and catalyst deactivation in the secondary stage. 

The recovery, regeneration, and repeated reuse of the active catalyst are of prime importance in substantially reducing the overall cost of coal liquefaction. The used catalysts usually remain in the bottoms products, which consist of nondistillable asphaltenes, preasphaltenes, unreacted coal, and minerals. The asphaltenes and preasphaltenes can be recycled with the catalyst in bottoms recycle processes. However, unreacted coal and minerals, if present in the recycle, dilute the catalyst and limit the amount of allowable bottoms recycle because they unnecessarily increase the slurry viscosity and corrosion problems. Hence, these useless components should be removed or at least reduced in concentration. If the catalyst is deactivated, reactivation becomes necessary before reuse. Thus, the design of means for catalyst regeneration and recycle is necessary for an effective coal liquefaction process. Several approaches to achieving these goals are discussed below. 

All of these problems are related to the performances of the catalysts used in coal liquefaction. Very active, durable, recoverable, and regenerable catalysts are most wanted in the primary liquefaction stage, where catalyst poisons from asphaltenes and minerals are most severe. Multifunctional catalysts should be designed by selecting supports with specific functions, such as strong but favorable interactions with catalytic species, resistance to poisons, and improved properties to allow easy recovery, while maintaining high activity. 

XIV. Design of Multistage Coal Liquefaction with Catalysts Yet to Be Developed... 

Coal liquefaction that can provide liquid fuels at the price of current petroleum (not cost but price) is one of the most important technologies that needs to be developed. The catalyst and control of its operating conditions are still key to technology for advanced coal liquefaction. The creative design of catalyst materials and reaction schemes is an important and challenging goal for the future. 

Many of the feedstocks for the chemical industry, especially aromatic hydrocarbons, were originally obtained as by-products from the carbonization of coal. (1,2) However, nowadays, most of these chemical feedstocks are derived from petroleum. Nevertheless, it is probable that, within the next few decades, the shortage of world reserves of petroleum will mean that BTX will once again have to be produced from coal, as will ethylene. It is, therefore, appropriate to examine ways in which these materials can be produced from coal the present investigation was designed to study the formation of BTX and ethylene by the thermal cracking of coal-derived materials from the NCB coal liquefaction/hydrogenation processes. (3)... 

Gas-liquid bubble columns and gas-liquid-solid slurry bubble columns are widely used in the chemical and petrochemical industries for processes such as methanol synthesis, coal liquefaction, Fischer-Tropsch synthesis and separation methods such as solvent extraction and particle/gas flotation. The hydrodynamic behavior of gas-liquid bubble columns and gas-liquid-solid slurry bubble columns are of great importance for the design and scale-up of reactors. Although the hydrodynamics of the bubble and slurry bubble columns has been a subject of intensive research through experiments and computations, the flow structure quantification of complex multi-phase flows are still not well understood, especially in the three-dimensional region. In bubble and slurry bubble columns, the presence of gas bubbles plays an important role to induce appreciable liquid/solids mixing as well as mass transfer. The flows within these systems are divided into two... 

Coal liquefaction processes are designed to clean coal chemically by removing ash, sulfur and to a lesser extent, nitrogen from a feed coal. The principal differences between the fuels tested at Plant Sweatt and their petroleum counterparts are that synthetic fuels have a higher carbon/hydrogen molar ratio (C/H,... 

The goal of the EDS coal liquefaction project is to develop the process to a state of commercial readiness. This means that the technology should be available at the end of the project to design and build a full-scale, pioneer commercial plant with a reasonable and acceptable level of risk. 

ER E discussions with Texaco and with Shell on bottoms processing are summarized herein. Texaco has indicated that its partial oxidation process could be applied to coal liquefaction bottoms on a commercial scale and that operation of their 12 T/D pilot plant with coal liquefaction bottoms representative of a projected commercial feedstock would be adequate to set the design basis for a commercial facility. Texaco indicated that three to four years after successful operation of the 12 T/D unit a commercial facility could be ready for startup. In initial discussions, Shell has indicated that development of the Shell/ Koppers partial oxidation process for coal liquefaction bottoms would involve operations of both their 6 T/D pilot plant and their 150 T/D demonstration unit. It was estimated that the 150 T/D facility might become available in the late 1980/early 1981 time frame for possible operation on vacuum bottoms. 

EDS Coal Liquefaction Project Technical Progress Reports prepared for the Department of Energy Interim Report FE-2353-13, EDS Commercial Plant Study Design, February,1978 1976 Phase IIIA Annual Report FE-2353-9, December, 1977 Phase IIIA Final Report, March, 1978 1977-1978 Phase IIIB Annual Report, FE-2893-17, September, 1978. 

We have our work divided into process engineering, process chemistry, catalysis, and support technology. As an example, one of the indirect liquefaction projects, tube wall reactor, deals with the design and operation of high thermal efficiency catalytic reactors for syn-gas conversion. Other activities are coal liquefaction properties of coal minerals, the role of catalysts, coal liquid product stability, and environmental impact—to name a few. 

The size of this investment, as well as the technological intensity, limits the number of companies capable of designing and efficiently operating coal liquefaction plants, and, as of... 

The SRC-I coal liquefaction process is designed to produce a clean, coal-derived solid fuel in a single, noncatalytic reaction step. (1) Design of a demonstration plant for the SRC-I process is new under way. (2) A two-step, hydrogen efficient modification of the noncatalytic SRC I technology has been proposed and studied extensively on a laboratory scale. (3-6) Two-step SRC I technology is also being tested in pilot plant scale facilities. 07, S)... 

Summary of Experiments. Fifteen coal liquefaction experiments were done using two coals and two solvents supplied by Mobil Research and Development Corporation. Each coal-solvent combination was tried at conditions designed to give conversions to pyridine solubles of about 65 and 80 percent of MAF coal. 

The measure used to designate the pyrrhotites observed in coal liquefaction residues is com monly the atom percent iron. Pollack and Spitler (4) have described the adaptation of the well-established x-ray diffraction method of determining atom percent iron in natural pyrrhotites to coal liquefaction residues. The atom percent iron was estimated by this technique to 0.1 atom percent. The atom percent iron values observed in liquefaction residues, and in natural pyrrhotites, range from about 46 to 50. The latter would be the essentially stoichiometric FeS, troilite (high pyrrhotite). Experimentally, substances with all compositions from 43 to 50 atom percent iron have been prepared (2). The pyrrhotites found in nature manifest atom percent iron values clustered around 46.67 (Fe Sg ... 

High-resolution MS provides significant information on the heterocompounds present in coal liquids. The technique can be applied equally well to coal extracts and to coal liquids. This information can be related to processing parameters. The method supports research and development efforts designed to either liquefy coal or to upgrade coal liquefaction products. The approach is limited only by instrumental resolving power and sample volatility. 

This reactor is a modification of the conventional moving-basket Carberry reactor. In the design of a falling-basket reactor for coal liquefaction, Alcorn et al. (1974) set five requirements ... 

Reactions involving gas, liquid, and solid are often encountered in the chemical process industry. The most common occurrence of this type of reaction is in hydroprocessing operations, in which a variety of reactions between hydrogen, an oil phase, and a catalyst have been examined. Other common three-phase catalytic reactions are oxidation and hydration reactions. Some three-phase reactions, such as coal liquefaction, involve a solid reactant. These and numerous other similar gas-liquid solid reactions, as well as a large number of gas-liquid reactions, are carried out in a vessel or a reactor which contains all three phases simultaneously. The subject of this monograph is the design of such gas-liquid -solid reactors. 

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