JPS6247919B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method of hydrogenating coal to produce an oily substance, and more particularly to a coal liquefaction method that improves the oily substance yield by incorporating a circulation system. Generally, a single-stage hydrogenation method and a two-stage hydrogenation method are known as coal liquefaction reactions, but the method of the present invention can be applied to either hydrogenation method. [Prior art] A method of increasing the hydrogen/carbon ratio in coal constituents by hydrogenating coal, that is, replacing a high melting point hydrocarbon compound (solid at room temperature) with a low melting point hydrocarbon compound (room temperature liquid). Methods for converting into () are well known. This method is generally referred to as a coal liquefaction method, and is carried out by applying high-temperature, high-pressure hydrogen in a highly hydrogen-donating hydrocarbon solvent in the presence or absence of a catalyst. Therefore, the products obtained by this reaction (generally hydrogenation reaction) include (1) various inorganic substances (ash) coexisting in the coal, and (2) hydrocarbons on which the hydrogenation reaction has not proceeded. system compound, (unreacted carbon),
(3) intermediate melting point hydrocarbons in which the hydrogenation reaction has progressed only slightly and the hydrogen/carbon ratio has not been sufficiently increased; (4) hydrocarbons in which the hydrogenation reaction has progressed moderately and a low melting point has been achieved; (5) Gaseous components that have undergone excessive hydrogenation or have a low molecular weight due to thermal decomposition, (6) Others (solvent, water, hydrogen gas, etc.) are mixed together. These separations or second-stage hydrogenation [the above components (2) and (3) are further hydrogenated to form (4)
Special attention has been paid to reactions that produce a large amount of components. [Problems to be solved by the invention] Substances contained in coal hydrogenation reaction products can be broadly classified into substance groups (1) to (6) as described above, but the main Considering the purpose, it can be said that the low melting point liquid hydrocarbons classified as (4) are very desirable targets. Therefore, it is required to further hydrogenate unreacted or insufficiently reacted substances classified as (2) and (3) to increase the yield of low-melting liquid hydrocarbons. On the other hand, in the method using hydrocarbon solvents as described above (commonly known as solvent refining method), low melting point liquid hydrocarbons are collected as distillate oil (naphtha and solvent fraction) by distillation after the hydrogenation reaction is completed. At the same time, the distillation residue [containing each of the substance groups (1), (2), and (3) above] is called solvent-refined coal, and its utilization means and uses are being explored. For example, one method is to use it itself as a fuel, but by providing a second hydrogenation reaction process and supplying it as a raw material,
Efforts are also being made to contribute to improving the yield of distillate oil as described above. However, since solvent-refined coal is essentially a distillation residue, it contains various components.For example, the components classified as (3) also include asphaltenes (components soluble in benzene and toluene) and puriasphaltenes (components soluble in benzene and toluene). There is also the problem that puriasphaltenes exhibit catalyst toxicity and inhibit the progress of the second stage hydrogenation reaction. Concerned about the above-mentioned circumstances, the present inventors focused on the fact that puriasphaltenes in solvent-refined coal have not been blessed with very good means of utilization or applications, and they ) We conducted various studies thinking that it would be a good idea to circulate it to the hydrogenation reaction region and contribute to improving the yield of distillate oil. Furthermore, when circulating puriasphaltenes, it is necessary to take measures to eliminate the harmful effects of accumulation of unnecessary substances due to circulation. [Means for Solving the Problems] The present invention is characterized in that the hydrogenation reaction product is subjected to an ash removal process to prevent ash accumulation in the circulation line, and that the preasphaltenes separated in the deasphalting process are The purpose of this method is to improve the yield of distillate by circulating it to the hydrogenation reaction. [Operation] The conditions of the hydrogenation reaction themselves are not limited in any way in the present invention. Therefore, the properties and particle size of the supplied coal, the type of solvent (use of circulating solvent), the reaction temperature and pressure, the presence or absence and type of catalyst, the amount of raw materials and various solvents used, etc. are determined according to the conventional method or improved method. It is only necessary to select a suitable hydrocarbon, and the object of the present invention is a method of adding hydrogen to the room-temperature solid hydrocarbon that constitutes coal to turn it into a room-temperature liquid hydrocarbon. Furthermore, there are no particular restrictions on whether or not to add secondary hydrogenation, or on the secondary hydrogenation reaction conditions at this time. FIG. 1 is a conceptual diagram illustrating the hydrogenation process of the present invention, and shows a process in which secondary hydrogenation is added. The present invention will be explained below according to this process. A slurrying solvent and a catalyst are added to the coal powder, heated to a high temperature, and added into the primary hydrogenation reaction zone. High-pressure hydrogen is introduced here, and a primary hydrogenation reaction is carried out at high temperature and high pressure. The obtained hydrogenated product is subjected to distillation, and the naphtha and solvent fractions, which are low-boiling fractions, are recovered, and the naphtha and excess solvent are made into products, and the solvent is circulated as a slurry solvent to the primary hydrogenation reaction zone. . The distillation residue is the solvent-refined coal (Coal Liquid) mentioned above.
Bottom: CLB), which contains ash derived from coal or catalyst in addition to unreacted high melting point hydrocarbon coal that has been insufficiently hydrogenated. Therefore, in this specification, the former high melting point hydrocarbon is referred to as CLB in the narrow sense, and the latter ash classification is sometimes referred to collectively as ash content. The basic gist of the present invention is to separate puriasphaltenes from this distillation residue and recirculate and feed it to the primary hydrogenation reaction zone. There is a problem of how to solve the problem of accumulation of reactive carbon. In other words, although the present invention is not limited to the means for separating puriasphaltenes from the distillation residue, since puriasphaltenes belong to a group of substances with a large number of carbon atoms in the distillation residues, separation of puriasphaltenes is necessary. With such a separation means, there is a problem that ash and unreacted charcoal are separated along with the preasphaltenes. For example, as mentioned above, puriasphaltenes are a hydrocarbon source that is insoluble in benzene and toluene, so a method of separating puriasphaltenes using the difference in solubility in benzene and toluene may be adopted; Since ash and unreacted charcoal behave together with the preasphaltenes as insoluble components, the separated preasphaltenes will be contaminated with ash and unreacted charcoal. Distillation and liquid chromatography methods can also be used as means for separating puriasphaltenes, but even with these methods, it is important to separate puriasphaltenes without contamination with ash. is not always easy. Therefore, when considering circulating and supplying the preasphaltenes separated from the distillation residue to the primary hydrogenation reaction zone as mentioned above, this preasphaltenes undergoes a hydrogenation reaction sequentially to lower its melting point, and is converted into, for example, benzene or Since it dissolves in toluene and is removed from the circulation line, there is no unreasonable reason for it to accumulate in the line, but the end-reacted coal and ash do not undergo hydrogenation, but rather are used as raw material coal. The problem arises of gradual accumulation in the line, as the catalyst is continually being replenished with new supplies. Therefore, in the present invention, a deashing step is provided as shown in Fig. 1 or 2 to prevent ash and unreacted coal (large particle size), which can be removed relatively easily, from accumulating in the system. A line will be provided to discharge the liquid to the outside of the system. (hereinafter referred to as rough demineralization). Common demineralization treatments include centrifugation, gravity sedimentation, solvent demineralization, filtration, etc., and CLB in the narrow sense mentioned above.
A part of it is also separated along with the ash. However, since only particles with a relatively large particle size are deashed, the deashing process can be simplified, and CLB accompanying ash and unreacted carbon can be minimized. The process will be explained below according to the flow shown in FIGS. 1 and 2. In Figure 1, the distillation residue is subjected to a rough deashing process, and the CLB, which contains fine ash content (ash content) that is relatively difficult to deash and unreacted charcoal, is sent to the deashing process, as described above. The puriasphaltenes are removed by means. In this step, the pre-asphaltenes that are removed are recycled to the primary hydrogenation step together with the previously separated ash and unreacted carbon that are difficult to deash. Further, as long as ash and unreacted carbon do not accumulate, CLB can be recycled as is to the primary hydrogenation step. Therefore, in Figure 1, there are two lines for removing ash and unreacted coal from the system, but the main line is the line for removing the deashed products, and the line for separating the deashed products is the main line. becomes secondary. The application ratio for these areas is based on the demineralized separate.
It should be determined by taking into consideration the CLB contamination rate and the ash contamination rate in the deasphalted material. Deashed oil is thus decalcified and demineralized.
oil (DAO) is supplied to the secondary hydrogenation process along with a portion of the solvent recovered in the distillation process. The naphtha that is the result of hydrogenation is recovered as a product, and the medium oil that has not been reduced to naphtha is
1 as HDAO (Hydrogenated Deashed oil)
It is recycled to the next hydrogenation step, but may be recovered as a product. Next, FIG. 2 will be explained. In the case of FIG. 2, the product liquid of the primary hydrogenation is directly subjected to the rough deashing step. The selection of deashing target and deashing method is as follows:
This is the same as the explanation in FIG. In Figure 1, the distillation residue is subjected to a rough deashing process, but the distillation residue is solid at room temperature, and although it becomes liquid when the temperature is raised, it has a high viscosity and requires the addition of a solvent for rough deashing. Is required. The method shown in FIG. 1 has advantages over the method shown in FIG. 2 in that an appropriate solvent can be selected, its recovery is easy, and the amount of distillation residue to be treated is significantly smaller than the amount of produced liquid. On the other hand, the second
In the figure, since the product liquid itself is liquid at room temperature, even if it is subjected to crude deashing as it is or a solvent is added for the purpose of adjusting the viscosity, the amount is small, and naphtha is recovered by distillation. It also has the advantage of being able to use medium-quality oil as is. The selection of Figure 1 or Figure 2 should be determined by the demineralization method employed. In the process shown in FIG. 1 of the present invention, deashing is performed before deashing, but there is no problem if it is performed after deashing. [Example] The following experiment was conducted using a 5-capacity autoclave. The initial pressure of hydrogen is 60.
Kg/cm ²・G, and the reaction temperature is 430°C and 460°C.
The temperature was divided into two series for comparison. In addition, the catalyst is iron-based and contains 3.0% by weight in terms of Fe (based on anhydrous and ash-free coal standards).
used. The results are shown in Table 1. Experiment 1: Coal and solvent (equivalent to no circulation). Experiment 2: Toluene solubles in CLB were added to coal and solvent (corresponding to asphaltene circulation). Experiment 3: Toluene insoluble content in CLB was added to coal and solvent (circulation of preasphaltene after rough deashing: equivalent to the example of the present invention).

[Table] As can be seen in Table 1, the yield of total oil was significantly improved in Experiments 2 and 3, which corresponded to experiments with circulation, compared to Experiment 1 without circulation. Also, when comparing Experiments 2 and 3, Experiment 3 uses toluene-insoluble matter, which was conventionally only discarded or discarded as an energy source, whereas Experiment 3 uses toluene-soluble matter, which was originally recognized to have recycling value. Even when compared to Experiment 2, it does not have any dark color, but rather gives a good result that surpasses Experiment 2 in terms of total oil yield. Also, looking at the conversion rate, in the case of the non-recycling type, there remains a considerable amount of unconverted material in the raw coal, but the pre-asphaltene recycling type (Experiment 3) of the present invention is similar to the asphaltene recycling type (Experiment 2). This shows an almost complete conversion rate, which shows the high hydrogenation efficiency. [Effects of the Invention] Since the present invention is configured as described above, it is possible to improve the hydrogenation rate by circulating and supplying the puriasphaltenes obtained by deasphalting to the hydrogenation process, and as a result, to improve the total yield of oily substances. We were able to achieve an improvement in the rate.
Also, by combining the rough deashing process, it is possible to prevent ash accumulation in the circulation line, and
By simplifying the deashing process itself to the extent that it prevents accumulation, the coal liquefaction process could be greatly advanced in terms of both economic efficiency and productivity.

[Brief explanation of the drawing]

FIGS. 1 and 2 are explanatory diagrams of embodiments of the process of the present invention.

Claims (1)

[Claims] 1 In a coal liquefaction method in which coal is subjected to a hydrogenation reaction, the solvent-purified coal obtained by the hydrogenation reaction is subjected to an ash removal process, and only the ash contained in the solvent-purified coal is removed to prevent accumulation in the system. A coal liquefaction method comprising a circulation system characterized in that the puriasphaltenes which are then supplied to a deasphalting step and separated are circulated and supplied to a hydrogenation reaction zone.