JPS6340834B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to the treatment of solvent-refined coal in a coal liquefaction process, and in particular to the treatment of inorganic substances and/or heavy organic substances (all of which are catalyst poisons) mixed in solvent-refined coal. The present invention relates to a method for efficiently removing such substances. The heavy organic matter referred to here is
For example, substances such as benzene-insoluble/pyridine-soluble substances (puriasphaltenes) act as catalyst poisons for the hydrogenolysis catalyst of solvent-refined coal. Contains catalyst and unreacted carbon. [Prior art] A method of increasing the hydrogen/carbon ratio in coal constituents by hydrogenating coal. In other words, a high melting point condensed aromatic compound that is solid at room temperature is turned into a liquid at room temperature by hydrogenolysis, etc. Methods for making it into shapes are known. This method is generally called a coal liquefaction method, but the solvent refining method is expected to have particularly high industrial efficiency. This method involves subjecting the extracted coal to a hydrogenation reaction using a highly hydrogen-donating hydrocarbon solvent, but in reality the reaction is carried out by slurrying raw coal with the above solvent. It is unavoidable that coal-derived inorganic substances are mixed in, and it is also unavoidable that heavy organic substances as by-products remain. Therefore, inorganic substances and heavy organic substances coexist in the residual liquid (commonly known as solvent-refined coal) after gas components and light oil to medium oil fractions are removed from the hydrogenation reaction product, and the hydrogenation reaction These inorganic substances and heavy organic substances are There is concern that it may have a serious adverse effect on the reaction system. [Problems to be Solved by the Invention] For example, if inorganic substances are directly sent to the secondary hydrogenation reaction, for example, if a fixed bed reactor is used, they may accumulate at the entrance and exit of the reactor or in the transport pipes, causing blockages. This poses a problem of hindering the smooth operation of the coal liquefaction reaction. In addition to the so-called benzene soluble fraction (asphaltene fraction), which is suitable as a raw material for the hydrogenation reaction, solvent refined coal contains hydrogenation catalysts such as benzene insoluble fraction/pyridine soluble fraction (puriasphaltene fraction). There are also heavy organic substances that deteriorate the decomposition characteristics of hydrogen, and depending on the type of secondary hydrogenation catalyst used, it may be inconvenient to circulate the latter as a raw material for the hydrogenation reaction. Therefore, we focused on the solvent-refined coal that remains after removing gas and light oil from the hydrogenation reaction product, or the solvent-refined coal that remains after removing the medium oil content, and investigate what is contained in these solvent-refined coals. It is necessary to establish a method that can efficiently remove inorganic substances and heavy organic substances. However, it is necessary to recognize that the particle size of, for example, inorganic substances mixed in solvent-refined coal is very small, for example, the maximum particle size is about 20 μm. Therefore, it is not possible to obtain a practical sedimentation velocity using the normal gravity sedimentation method. The present invention was made in consideration of this situation, and as a result of searching for a method that can effectively remove inorganic substances and heavy organic substances contained in solvent-refined coal, the present invention was completed. It came to this. [Means for Solving the Problems] The method of the present invention, which is effective in achieving the above object, is to contact and mix a deasphalting solvent with solvent-refined coal at a high temperature exceeding 150°C. The gist lies in promoting the growth of these particles by utilizing the adhesion properties of coexisting heavy organic matter under high temperatures, and then reducing the adhesion of the growing particles to each other by cooling to below 150°C. As a result, it was possible to cause the grown particles to settle by gravity, to prevent them from adhering to each other after settling, and to maintain discharge workability. Note that the amount of heavy organic matter accompanying the inorganic substance can be adjusted to any desired ratio by appropriately selecting the type of solvent. [Effect] As mentioned above, the particle size of inorganic substances is small, and it was thought that promoting particle growth would be effective in obtaining a practical sedimentation rate. After conducting various studies from this point of view, we found that the solvent-refined coal contains heavy organic substances that are insoluble in solvents, and if this is softened by applying heat, the heavy organic substances surrounding the inorganic particles become adhesive. We have come to the conclusion that this may cause fine inorganic particles to adhere to each other under mixing conditions and promote particle growth. Therefore, we carried out heating melting experiments on solvent-refined coal and obtained the following results. An autoclave having an internal volume of about 8 liters was charged with deasphalting solvent and solvent refined charcoal powder at a weight ratio of 4:1, and then heated under nitrogen atmosphere with stirring. In addition, cyclohexane was used as the deasphalting solvent,
The stirring conditions were 720 rpm and the temperature increase rate was 260°C/hr. During the temperature rise, a portion of the content was extracted without stopping stirring, and the concentration of inorganic substances in the solution was measured. The results are shown in Figure 2, and the concentration of inorganic substances decreased as the temperature increased. This means that the inorganic substances precipitated as the temperature rose, and the reason for this is that as the temperature rose, the preasphaltenes increased their adhesion, promoting the growth of the coexisting inorganic particles, and causing the precipitation. This seems to be due to increased sex. The CLB (Coal Liquid
Bottom: distillation residue of coal liquefaction product) is
It consists of the composition shown in the table (based on solvent fractionation), and the raw material CLB was pulverized to a size of 250 μm or less.

【table】

[Table] Through the above basic experiment, we found that the concentration of inorganic substances sharply decreases when the temperature is higher than about 150°C (in other words, the sedimentation property of inorganic substances sharply increases). We conducted the following experiments from the perspective of applying this method to the operation of Figure 3 shows a continuous deashing flow, in which powdered or fluidized solvent-refined coal and a deasphalting solvent (e.g. cyclohexane) are mixed, preheated to 80 to 120°C, and then a spiral tube type After heating and melting in the preheater and reaching the specified temperature, the material is transferred to a sedimentation tank (vertical type,
(inner diameter: 50 mmφ, height: approximately 1.5 m), and gravity sedimentation separation using upward flow was performed. The relationship between the melting temperature and the deashing/deashing performance is shown in Table 2, and when the melting temperature was about 130°C, deashing/deashing was insufficient. This point is consistent with the trend shown in Figure 2, and is preferably
It has been found that it is better to contact at a high temperature of over 150°C. However, this temperature cannot be uniformly determined because it varies depending on the softening temperature of the heavy organic matter contained in the solvent-refined coal.

[Table] In this experiment, the heavy organic substances to be removed were puriasphaltenes (benzene soluble/pyridine insoluble). On the other hand, if the contact temperature is too high or the contact time is too long, the adhesion of the heavy organic substances It was predicted that the contact temperature would be too strong or the particles would grow too much over time, causing various problems.
It has been learned that it is best to keep the temperature below 250°C, more preferably below 220°C, and for the contact time to be 30 minutes or less. If the contact time is too short, the particles will not grow sufficiently and will not exhibit good settling properties, so a contact time of about 5 minutes or more is desired. However, since the contact time and the contact temperature are related to each other, a short time is better if the temperature is high, and a long time is better if the temperature is low, so there is no limitation here. Unless active cooling means are applied to the heated liquid, it will remain preheated for a considerable period of time, depending on its heat capacity, and the precipitated inorganic substances will adhere to each other. In such a state, bridging occurs in the discharge piping, particularly in the throttle piping, making it easy to cause a blockage accident, making it impossible to discharge the sediment. Therefore, in the present invention, the temperature of the sedimentation system is actively lowered to 150°C or less, for example, immediately after mixing or by mixing a cooling solvent into the sedimentation part, to prevent excessive adhesion of sediment particles. . Note that the cooling means may be a general heat transfer type heat exchanger, and the cooling means is not limited to the present invention. Note that the solvent-refined coal that is the subject of the present invention is not limited to one that is finally taken out as a powder, but may be a liquid distillation residue from a coal liquefaction process. For example, deashing is performed by contacting at high temperature and then cooling through heat transfer type heat exchange. The results of deasphalting are shown in Table 3.

[Table] [Example] Fig. 1 is a flow explanatory diagram of an example of an implementation apparatus created based on the above considerations, in which solvent-refined coal and deasphalted solvent are brought into contact in a contactor, and inorganic particles are growth is promoted. A cooling solvent is added after an appropriate time and the particles are introduced into the settling tank while overgrowth occurs. Here, since the inorganic substances settle in a time that does not cause any practical problems, the sediment is extracted as sludge, and the recovered deasphalt solvent is circulated. On the other hand, the toplight liquid contains almost no inorganic substances or heavy organic substances (for example, when it comes to inorganic substances,
1000ppm or less), and when this is separated and subjected to heated flash distillation, a demineralized oil is obtained. The remainder may be used cyclically as a deasphalting solvent. [Effects of the Invention] Since the present invention is configured as described above, sedimentation separation can be performed by growing inorganic particles, and even particles that could not be removed by conventional filter methods can be removed by gravity. It has become possible to grow them to a size suitable for sedimentation. In addition, heavy organic substances can also be removed, and the removal rate can be controlled by the contact temperature, contact time, and selection of the deasphalting solvent. As inorganic substances and heavy organic substances can be easily and efficiently removed as described above, clogging of the secondary hydrogenation reaction system by the former is prevented, and the secondary hydrogenation catalyst is prevented from being blocked by the latter. This prevented deterioration and ultimately contributed significantly to smoothing the hydrogenation reaction and improving reaction efficiency.

[Brief explanation of the drawing]

FIG. 1 is a flow explanatory diagram showing an embodiment of the present invention;
FIG. 2 is a graph showing the relationship between contact temperature and inorganic substance concentration, and FIG. 3 is a flow diagram of the experimental apparatus.

Claims (1)

[Claims] 1. When removing inorganic substances and heavy organic substances from solvent-refined coal using the gravity sedimentation method, a deasphalting solvent is used.
After promoting the growth of particles of inorganic substances and heavy organic substances by contact-mixing with solvent-refined coal at a high temperature exceeding 150°C, and then cooling the mixture to below 150°C to reduce the adhesion of the grown particles to each other. A method for removing inorganic substances and heavy organic substances from solvent-refined coal, which comprises removing sediments from the system in a gravity sedimentation process.