Performance study in the hydrotreatment of coal with coal-derived solvents

Hydrotreatment of coal in the presence of hydrogen donor solvents is considered to be a potential route for developing value-added carbon products. The aim of this research was to investigate the use of coal-derived solvents as replacements for expensive hydrogendonor solvents like tetralin, in the production of hydrogen rich carbon products. Three coal-derived solvents obtained from the metallurgical coke ovens, namely Heavy Creosote Oil (HCO), Carbon Black Base (CBB) and Refined Chemical Oil (RCO), were utilized as hydrogen donor solvents in the hydrotreatment process. The coal-alone conversion in producing THF solubles decreased in the order as CBB\u3eHCO\u3eRCO. Process-derived (recovered) solvents were isolated as vacuum distillation overheads and tested for their effectiveness towards producing THF solubles. The coal-alone conversion for these recovered was found to be comparable to the starting fresh solvents. An average mass loss of 7-10% was observed for the fresh solvents whereas the mass loss increased slightly to 10-13% for the recovered solvents during the hydrotreatment runs. The residue from the vacuum distillation i.e. the pitch, was characterized by testing for softening point, ash content, elemental analysis and optical texture. The coke yield and softening point of the pitch followed a linear dependence on the amount of solvents distilled from the product mixture. The effect of temperature and reaction atmosphere was also studied on the hydrotreatment process. The coal-alone conversion increased with higher temperature and a hydrogen atmosphere was found to be crucial. The optimum process temperature was found to be 450°C under 500 psig hydrogen pressure. Reaction conditions did not affect the recovered solvent performance upon recycle in producing THF solubles. The ash content of the pitches was found to be low i.e 0.2%. The optical texture of the cokes was found to have an anisotropic structure. The elemental composition of the pitches showed higher hydrogen-to-carbon ratio than the starting coal and was found to be similar irrespective of reaction conditions. Finally, successive use of only recovered solvents and/or blends of fresh and recovered solvents were studied to mimic a continuous hydrotreament operation. The coal-alone conversion decreased after going through a maximum in both the cases. While the decreasing trend continued for the pure recovered solvents, the coal-alone conversion was found to stabilize for the blends

DEVELOPMENT OF CONTINUOUS SOLVENT EXTRACTION PROCESSES FOR COAL DERIVED CARBON PRODUCTS

This NETL sponsored effort seeks to develop continuous technologies for the production of carbon products, which may be thought of as the heavier products currently produced from refining of crude petroleum and coal tars obtained from metallurgical grade coke ovens. This effort took binder grade pitch, produced from liquefaction of West Virginia bituminous grade coal, all the way to commercial demonstration in a state of the art arc furnace. Other products, such as crude oil, anode grade coke and metallurgical grade coke were demonstrated successfully at the bench scale. The technology developed herein diverged from the previous state of the art in direct liquefaction (also referred to as the Bergius process), in two major respects. First, direct liquefaction was accomplished with less than a percent of hydrogen per unit mass of product, or about 3 pound per barrel or less. By contrast, other variants of the Bergius process require the use of 15 pounds or more of hydrogen per barrel, resulting in an inherent materials cost. Second, the conventional Bergius process requires high pressure, in the range of 1500 psig to 3000 psig. The WVU process variant has been carried out at pressures below 400 psig, a significant difference. Thanks mainly to DOE sponsorship, the WVU process has been licensed to a Canadian Company, Quantex Energy Inc, with a commercial demonstration unit plant scheduled to be erected in 2011

Development of Continuous Solvent Extraction Processes For Coal Derived Carbon Products

In this reporting period, tonnage quantities of coal extract were produced but solid separation was not accomplished in a timely manner. It became clear that the originally selected filtration process would not be effective enough for a serious commercial process. Accordingly, centrifugation was investigated as a superior means for removing solids from the extract. Results show acceptable performance. Petrographic analysis of filtered solids was carried out by R and D Carbon Petrography under the auspices of Koppers and consultant Ken Krupinski. The general conclusion is that the material appears to be amenable to centrifugation. Filtered solids shows a substantial pitch component as well as some mesophase, resulting in increased viscosity. This is likely a contributing reason for the difficulty in filtering the material. Cost estimates were made for the hydotreatment and digestion reactors that would be needed for a 20,000 ton per year demonstration plants, with the aid of ChemTech Inc. The estimates show that the costs of scaling up the existing tank reactors are acceptable. However, a strong recommendation was made to consider pipe reactors, which are thought to be more cost effective and potentially higher performance in large scale systems. The alternate feedstocks for coke and carbon products were used to fabricate carbon electrodes as described in the last quarterly report. Gregory Hackett successfully defended his MS Thesis on the use of these electrodes in Direct Carbon Fuel Cell (DCFC), which is excerpted in Section 2.4 of this quarterly report

DEVELOPMENT OF CONTINUOUS SOLVENT EXTRACTION PROCESSES FOR COAL DERIVED CARBON PRODUCTS

The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. The largest applications are those which support metals smelting, such as anodes for aluminum smelting and electrodes for arc furnaces. Other carbon products include materials used in creating fuels for the Direct Carbon Fuel Cell, metals smelting, especially in the aluminum and steel industries, as well as porous carbon structural material referred to as ''carbon foam'' and carbon fibers. During this reporting period, coking and composite fabrication continued using coal-derived samples. These samples were tested in direct carbon fuel cells. Methodology was refined for determining the aromatic character of hydro treated liquid, based on Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR). Tests at GrafTech International showed that binder pitches produced using the WVU solvent extraction protocol can result in acceptable graphite electrodes for use in arc furnaces. These tests were made at the pilot scale

Development of Continuous Solvent Extraction Processes for Coal Derived Carbon Products Quarterly Report

The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. These carbon products include materials used in metals smelting, especially in the aluminum and steel industries, as well as porous carbon structural material referred to as ''carbon foam'' and carbon fibers. During this reporting period, efforts have focused on the facility modifications for continuous hydrotreating, as well as developing improved protocols for producing synthetic pitches

Development of Continuous Solvent Extraction Processes for Coal Derived Carbon Products Quarterly Report

The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. The largest applications are those which support metals smelting, such as anodes for aluminum smelting and electrodes for arc furnaces. Other carbon products include materials used in creating fuels for the Direct Carbon Fuel Cell, and porous carbon structural material referred to as ''carbon foam'' and carbon fibers. During this reporting period, hydrotreatment of solvent was completed in preparation for pitch fabrication for graphite electrodes. Coal digestion has lagged but is expected to be complete by next quarter. Studies are reported on coal dissolution, pitch production, foam synthesis using physical blowing agents, and alternate coking techniques

DEVELOPMENT OF CONTINUOUS SOLVENT EXTRACTION PROCESSES FOR COAL DERIVED CARBON PRODUCTS

This NETL sponsored effort seeks to develop continuous technologies for the production of carbon products, which may be thought of as the heavier products currently produced from refining of crude petroleum and coal tars obtained from metallurgical grade coke ovens. This effort took binder grade pitch, produced from liquefaction of West Virginia bituminous grade coal, all the way to commercial demonstration in a state of the art arc furnace. Other products, such as crude oil, anode grade coke and metallurgical grade coke were demonstrated successfully at the bench scale. The technology developed herein diverged from the previous state of the art in direct liquefaction (also referred to as the Bergius process), in two major respects. First, direct liquefaction was accomplished with less than a percent of hydrogen per unit mass of product, or about 3 pound per barrel or less. By contrast, other variants of the Bergius process require the use of 15 pounds or more of hydrogen per barrel, resulting in an inherent materials cost. Second, the conventional Bergius process requires high pressure, in the range of 1500 psig to 3000 psig. The WVU process variant has been carried out at pressures below 400 psig, a significant difference. Thanks mainly to DOE sponsorship, the WVU process has been licensed to a Canadian Company, Quantex Energy Inc, with a commercial demonstration unit plant scheduled to be erected in 2011

Development of Continuous Solvent Extraction Processes for Coal Derived Carbon Products Quarterly Report

The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. These carbon products include materials used in metals smelting, especially in the aluminum and steel industries, as well as porous carbon structural material referred to as ''carbon foam'' and carbon fibers. Table 1 provides an overview of the major markets for carbon products. Current sources of materials for these processes generally rely on petroleum distillation products or coal tar distillates obtained as a byproduct of metcoke production facilities. In the former case, the American materials industry, just as the energy industry, is dependent upon foreign sources of petroleum. In the latter case, metcoke production is decreasing every year due to the combined difficulties associated with poor economics and a significant environmental burden. Thus, a significant need exists for an environmentally clean process which can used domestically obtained raw materials and which can still be very competitive economically

Development of Continuous Solvent Extraction Processes for Coal Derived Carbon Products Quarterly Report

The purpose of this DOE-funded effort is to develop continuous processes for solvent extraction of coal for the production of carbon products. The largest applications are those which support metals smelting, such as anodes for aluminum smelting and electrodes for arc furnaces. Other carbon products include materials used in creating fuels for the Direct Carbon Fuel Cell, metals smelting, especially in the aluminum and steel industries, as well as porous carbon structural material referred to as ''carbon foam'' and carbon fibers. During this reporting period, efforts have focused on the development of carbon electrodes for Direct Carbon Fuel Cells (DCFC), and on carbon foam composites used in ballistic armor, as well as the hydrotreatment of solvents used in the basic solvent extraction process. A major goal is the production of 1500 pounds of binder pitch, corresponding to about 3000 pounds of hydrotreated solvent

PRODUCTION OF CARBON PRODUCTS USING A COAL EXTRACTION PROCESS

This Department of Energy National Energy Technology Laboratory sponsored project developed carbon products, using mildly hydrogenated solvents to extract the organic portion of coal to create synthetic pitches, cokes, carbon foam and carbon fibers. The focus of this effort was on development of lower cost solvents, milder hydrogenation conditions and improved yield in order to enable practical production of these products. This technology is needed because of the long-term decline in production of domestic feedstocks such as petroleum pitch and coal tar pitch. Currently, carbon products represents a market of roughly 5 million tons domestically, and 19 million tons worldwide. Carbon products are mainly derived from feedstocks such as petroleum pitch and coal tar pitch. The domestic supply of petroleum pitch is declining because of the rising price of liquid fuels, which has caused US refineries to maximize liquid fuel production. As a consequence, the long term trend has a decline in production of petroleum pitch over the past 20 years. The production of coal tar pitch, as in the case of petroleum pitch, has likewise declined significantly over the past two decades. Coal tar pitch is a byproduct of metallurgical grade coke (metcoke) production. In this industry, modern metcoke facilities are recycling coal tar as fuel in order to enhance energy efficiency and minimize environmental emissions. Metcoke production itself is dependent upon the production requirements for domestic steel. Hence, several metcoke ovens have been decommissioned over the past two decades and have not been replaced. As a consequence sources of coal tar are being taken off line and are not being replaced. The long-term trend is a reduction in coal tar pitch production. Thus import of feedstocks, mainly from Eastern Europe and China, is on the rise despite the relatively large transportation cost. To reverse this trend, a new process for producing carbon products is needed. The process must be economically competitive with current processes, and yet be environmentally friendly as well. The solvent extraction process developed uses mild hydrogenation of low cost oils to create powerful solvents that can dissolve the organic portion of coal. The insoluble portion, consisting mainly of mineral matter and fixed carbon, is removed via centrifugation or filtration, leaving a liquid solution of coal chemicals and solvent. This solution can be further refined via distillation to meet specifications for products such as synthetic pitches, cokes, carbon foam and fibers. The most economical process recycles 85% of the solvent, which itself is obtained as a low-cost byproduct from industrial processes such as coal tar or petroleum refining. Alternatively, processes have been developed that can recycle 100% of the solvent, avoiding any need for products derived from petroleum or coal tar