LIQUID FUEL FROM COAL First Year of Operation of Coal Hydrogenation Demonstration Plant at Louisiana, Mo. L. L. HIRST AND C. C. CHAFFEE Bureau of Mines, Louisiana, Mo.
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HE Bureau of Mines hydrogenation demonstration plant at Louisiana, Mo. [Kastens, M. L., with Hirst, L. L., and Chaffee, C. C., IND. ENG.CHEM.,41, 870 (1949)], has now made
five runs on the hydrogenation units during the f i s t year of operations. The first was a vapor phase run at 10,000 pounds per square inch to hydrogenate petroleum and lignite-tar-oil distillates to high-quality Diesel fuel and motor gasoline. After the vapor phase run, it was considered advisable to reweld all 3/s-inch nozzles on the high-pressure piping to obtain full penetration of the weld, which required an extended shutdown to complete. Four runs have been made on the liquid phase unit, the first being a %month exploratory tar-oil run to test the performance of equipment and instrumentation. This run was followed by a second long shutdown in which over 50 important process and equipment changes were incorporated in the plant. Three runs have followed, in which substantial improvement in operation was attained and over 1000 tons of coal were hydrogenated. However, troubles with injection pumps and instruments, particularly those measuring temperature, persisted and caused early termination of the first two runs. Further changes in pumping equipment and instrumentation, along with improvements in paste preparation and solids removal from heavy recycle oils, have made possible longer runs for the produrtion of synthetic fuels. From the beginning, it was realized that injection of liquids a t 10,000 pounds presented a very severe pumping problem. At first, the difficulties seemed to hinge around selection and proper break-in of packing; accordingly, numerous tests were made using various combinations of other soft packing. Finally, it was determined that commercial rubber duck chevron packing backed up with steel support rings faced with copper gave satisfactory performance and protection to the rods. Fortunately, i t has turned out that actual operating conditions are less severe than break-in, owing to the cushioning effect of the oil and gas mixtures in the discharge piping and vessels at high pressures. Many of the liquid end blocks have developed cracks between the suction and discharge valves, which are located a t the centers of the blocks. Experience to date has shown that satisfactory steam pumps for injection must include the following: 1. Rigid construction to assure maintenance of alignment 2. The use of materials of high tensile strength in the fluid end parts subjected to high pressure 3. Openings in fluid end blocks must be held to a minimum 4. Rigid guiding of moving parts at the fluid end 5. Higher standards of workmanship and construction details than are usual in oil pumps
bestos and fiber-glass insulated wires without pressure-tight seal have been substituted. While the insulation is capable of with standing temperatures up to 1000° F., it is not moisture-resistant and a desiccant must be used to keep the installation dry. The most promising instrument in liquid-level indication and control has been the development of a gamma-ray instrument to control the level in the hot catchpot. This instrument essentially consists of an ionization chamber (super Geiger counter) measuring the radiation from a radium source inside the vessel. The variation in radiation through the oil level in the vessel is transmitted to a receiver that in turn pneumatically controls the letdown valve from the vessel. This instrument has controlled the level of the hot catchpot within a narrow range and has the distinct advantage of low maintenance. The operation of diaphragm-actuated valves has been one of the major problems in obtaining satisfactory instrument control of rates of flow, particularly with the spring-loaded valves in the letdown lines from the hot and cold catchpots and the highpressure gas scrubber. Cemented tungsten carbide valve tips and seats were shattered by impact, and in those instances where the service was hard-heavy oil-bearing suspended solidserosion was severe. Types 304 and 416 stainless steels stand u p under impact but are rapidly eroded. Chromium-cobalttungsten alloy tips have shown the best over-all resistance to both impart and erosion. The coal-paste preheater is of unusual design-a four-re11 radiant type with vertical, steam-jacketed hairpin tubes, having all joints at the top of the furnaces. As a means for heating paste this heater has given very satisfactory service over more than 100 days of operation, even when 2.5 times the design pastegas volume is added to the full throughput of paste a t 7500 pounds per square inch operating pressure, which reduces the transfer rate below that a t the design pressure, 10,300 pounds per square inch. No evidence of coke formation has been encountered to date. The responses to changes in heat input are somewhat slower than for a conventional radiant-type heater. Wyoming Rock Springs coal has been used for all the liquid phase operations to date. During the fourth run lasting 20 days an average of 48 tons of coal per day have been processed a t an average conversion temperature of 867’ F., under 7400 pounds per square inch total pressure and 6360 pounds per square inch hydrogen partial pressure. The liquefaction has not dropped below 90%. Stannous oxalate, in the proportion 0.15% of the dry coal, has been used as the catalyst, but will be replaced by an iron catalyst. RECEIVED June 29, 1950.
The principal difficulties in temperature measurements encountered to date occurred in the converters. The thermocouples are spaced a t 6-foot intervals in thermowells designed to withstand 11,000 pounds per square inch external pressure. Bare wire threaded through two-hole porcelain insulators was first used. For protection against escaping hydrogen if it penetrated the walls, the outer ends of the tubes were closed, and the thermocouple lead wires were passed through soapstone disks crushed in cover joint to make a pressure-tight seal. When well made these seals are satisfactory, but they were discarded after the second run because of the difficulty in making them. As-
CORRECTION.In the article on “Thermodynamic Correlation of Vapor-Liquid Equilibria. Determination of Activity Coefficients from Relative Volatility” [IND. ENG.CHEM.,42, 122 (1950)]a correction should be made in Equation 17. The coefficient of the term corresponding to R = 1 and T = 4 should be 5/2 rather than 15/4 as shown, and the coefficient of the term corresponding to R = 4 and T = 5 should be -24/5 rather than -6/5 as shown. ROGER GILMONT
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