JPS61276891A - Method for liquefying coal containing circulation system - Google Patents

Abstract

PURPOSE:To improve the yield of a liquid hydrocarbon, by subjecting solvent- purified coal obtained by hydrogenation reaction of coal to a deashing step, removing only the ash, and circulating preasphaltene separated in the deasphalting step through the hydrogenation reaction. CONSTITUTION:For example, a slurrying agent and catalyst are added to coal dust, and the resultant mixture is brought to a high-temperature state. The mixture is then fed to the primary hydrogenation region, and high-pressure hydrogen is introduce thereinto to carry out the primary hdrogenation reaction at a high temperature under high pressure. The hydrogenated material is then distilled to separate naphtha and a solvent fraction as a product. The solvent- purified coal (CLB) is then subjected to a deashing step and deashed to prevent the accumulation of the ash in the system. After deashing, the CLB is fed to a deasphalting step to separate preasphaltene, which is circulated through the primary hydrogenation step to improve the yield of the distillate oil.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing an oil component by hydrogenating coal.
In detail, it relates to a coal liquefaction method that improves oil fraction 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.

C. Prior Art] A method of increasing the hydrogen/carbon ratio in the coal composition by hydrogenating coal, that is, replacing a high melting point hydrocarbon compound (solid at room temperature) with a low melting point hydrocarbon compound (liquid at room temperature). 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 and 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) hydrocarbon compounds on which the hydrogenation reaction has not proceeded.

(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, and (4) hydrocarbons in which the hydrogenation reaction has progressed moderately. Liquid hydrocarbons with a low melting point, (5) gaseous components that have undergone excessive hydrogenation or have a low molecular weight due to thermal decomposition, (6) others (solvents, water, hydrogen gas, etc.), etc. However, much attention has been paid to their separation or second-stage hydrogenation (a reaction in which components (2), 4, and (3) are further hydrogenated to produce a large amount of component (4)), etc. ing.

[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 the most desirable target substances. 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 a hydrocarbon solvent as described above (commonly known as the 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 [above ((
1), (2).

(3) containing each substance group] is called solvent-refined coal, and its usage and applications are being explored. For example, one method is to use it itself as a fuel, but the second hydrogenation reaction step Efforts have also been made to contribute to improving the yield of distillate oil as described above by supplying it as a raw material. However, since solvent-refined coal is essentially a distillation residue, it contains various components.For example, the components classified in (3) also include asphaltenes (components soluble in benzene and toluene) and puriasphaltenes (components soluble in benzene and toluene). Concerned about the above situation, the inventors of the present invention are concerned about the above-mentioned circumstances, and have developed a solvent-refined coal. We focused on the fact that the puriasphaltenes in the water have not been well-utilized or used in the past, and we improved the yield of distillate by circulating them back to the hydrogenation reaction region (corresponding to the first stage). We considered that it would be a good idea to contribute to this, and conducted various studies. 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 step to prevent the accumulation of ash in the circulation line, and that the preasphaltenes separated in the removal step are removed by water. The purpose of this is to improve the yield of distillate oil by circulating it to the addition 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 of a catalyst and the type, as well as the amount of raw materials and various solvents used, etc. are selected according to conventional or improved methods. In short, the subject of the present invention is a method of adding hydrogen to room-temperature solid hydrocarbons constituting coal to make them into room-temperature liquid hydrocarbons. 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 to the primary hydrogenation reaction area as a slurry solvent. do. The distillation residue is treated with the above-mentioned solvent-refined coal (CoalLi).
(quid bottom: CLB), which contains ash from coal white rice or catalyst-derived ash 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 a narrow sense, and the latter ash classification is sometimes referred to collectively as ash content.

The basic point of the present invention is to separate puriasphaltenes from this distillation residual liquid and circulate and supply them to the primary hydrogenation reaction zone. There is a problem of how to solve the problem of accumulation of reactive carbon. That is, although the present invention does not limit the means for separating puriasphaltenes from the distillation residue, since puriasphaltenes belong to the group of substances with the largest number of carbon atoms in the distillation residue, the separation is aimed at separating puriasphaltenes. With this method, there is a problem that ash and unreacted substances are separated along with the preasphaltenes. For example, as mentioned above, since the preasphaltenes are hydrocarbons that are insoluble in benzene and toluene, A method of separating puriasphaltenes using the difference in solubility can be adopted, but in this method, ash and unreacted substances act together with the puriasphaltenes as insoluble components, so the separated puriasphaltenes contain ash and unreacted components. Unreacted particles will be mixed in.

Distillation and liquid chromatography can also be used as means for separating puriasphaltenes, but even with these methods, it is not always easy to separate puriasphaltenes without ash contamination. Therefore, when considering circulating and supplying the preasphaltene separated from the distillation residue to the primary hydrogenation reaction zone as mentioned above, this preasphaltene undergoes a hydrogenation reaction sequentially to lower its melting point, and, for example, benzene Since it is dissolved in toluene and removed from the circulation line, there is no unreasonable problem of accumulation in the line, but unreacted and ash content does not undergo hydrogenation, but rather is removed from the circulation line. Since new supplies of coal and catalyst are constantly being received, the problem arises of gradual accumulation in the line.

Therefore, in the present invention, a deashing step is provided as shown in Figure 1 or Figure 2 to prevent ash that can be relatively easily deashed and unreacted particles (large particle size) 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), the commonly used demineralization processes are centrifugation and double gravity sedimentation.

This method is a solvent deashing method, a filtration method, etc., and a part of the CLH in the narrow sense mentioned above is 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 caused by ash content and unreactedness can be minimized. Part 1 below
This will be explained according to the flow shown in FIG.

For the first cause, the distillation residue is subjected to a rough deashing process, and the CLB containing relatively hard fine ash (ash content ■) and unreacted content (■) is sent to the deashing process. , Priasqualten is removed by means such as those described above. In this step, the unseparated ash (1) and unreacted ash, which are difficult to deash, and the unreacted puriasphaltenes are recycled together with the puriasphaltenes to the primary hydrogenation step.

In addition, as long as ash and unreactedness do not accumulate, CLB
can also be recycled as is to the primary hydrogenation step.

Therefore, in Figure 1, there are two lines for removing ash content and unreacted substances from the system, but the main line is the line for removing the demineralized products, and the line for separating the tax base removal products is the secondary line. become a target. The amount or application ratio of these should be determined in consideration of the CLB mixing rate in the demineralized product and the ash content in the demineralized product.

The oil thus deashed and taxed (Deashed)
il:DAO) is supplied to the secondary hydrogenation step together with a portion of the recovered solvent in the distillation step. The naphtha that is the result of hydrogenation is recovered as a product, and the medium oil that has not yet been reduced to naphtha is processed into HD A O (H7
It is recycled to the primary hydrogenation step as drogenated deashed oil, but it may be recovered as a product.

Next, FIG. 2 will be explained. In the case of Figure 2, the product liquid of the primary hydrogenation is directly subjected to the crude deashing process, and the selection of the deashing target and deashing method is as follows.

This is the same as the explanation for No. 11N. 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 no solvent for rough deashing. Addition, etc. is required. Compared to the method shown in FIG. 2, the method shown in FIG. 1 has the advantage that an appropriate solvent can be selected, its recovery is easy, and the amount of distillation residue to be treated is significantly smaller than that of the produced liquid. On the other hand, in Figure 2, since the product liquid itself is liquid at room temperature, even if it is subjected to rough deashing as it is or a solvent is added for the purpose of adjusting the viscosity, the quantity is small and it can be recovered by distillation. It has the advantage that naphtha and medium-quality oil can be used as they are.

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 51-capacity autoclave. The initial hydrogen pressure is 60 kg/cs in both cases.
+2 San G? The reaction temperature is 430℃ and 460℃.
The temperature was divided into two series and compared. In addition, the catalyst is iron-based, and Fe
It was used in an amount of 3.0% by weight (based on anhydrous and ash-free coal).

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: corresponds to the example of the present invention).

As can be seen in Table 1, the yield of the 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, there was no color retention, and rather a good result was obtained that surpassed Experiment 2 in terms of total oily yield.

Also, looking at the conversion rate, in the case of the non-recycling type, there is still a considerable amount of raw material converted from raw coal in Central America, but the pre-asphaltene recycling type of the present invention (Experiment 3) is different from that of the asphaltene recycling type (Experiment 2).
) shows an almost complete conversion rate, which helps to understand 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 tax revenue to the hydrogenation process, and by extension, to improve the total yield of oily products. I was able to achieve this.

In addition, by combining the coarse deashing process, it is possible to prevent ash accumulation in the circulation line, and by simplifying the deashing process itself to the extent that prevents accumulation, the coal liquefaction process can be made more economical and productive. We were able to make significant progress on both fronts.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams of an embodiment of the process of the present invention. Applicant: Kobe Steel, Ltd. (and 4 others) Figure 1 coal powder Slurrying solvent catalyst naphtha Figure 2- naphtha

Claims (1)

[Claims] 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 step to remove only the ash contained in the solvent-purified coal to prevent accumulation in the system, and then A coal liquefaction method including a circulation system characterized in that preasphaltene, which is supplied to a deasphalting step and separated, is circulated and supplied to a hydrogenation reaction zone.