JPS63270792A - Coal liquefaction method - Google Patents

Abstract

PURPOSE:To perform coal liquefaction, in which various types of coals are employed, without trouble in a vacuum distillation column, by regulating the ash content and solvent-extractable content of coal liquefaction residue so as to be in particular ranges on the basis of the test data of the properties of each type of coal previously obtd. using simple experimental apparatuses. CONSTITUTION:The properties of coal liquefaction residue when each type of coal is used are previously tested using simple experimental apparatuses, such as an autoclave. Based on the test data, the mixing ratio of different types of coals is selected so as to cause the ash content to be 0.4 or less and cause the content of toluene solubles, out of solvent extractable components, to be 0.3 or more.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for establishing stable operation of a coal liquefaction process by stabilizing the ability to extract liquefied residue from a distillation column.

(Prior art) In the general coal liquefaction method, pulverized coal of a single coal type is made into a slurry with a solvent and heated to 400 to 450°C in a preheater.
The coal is liquefied by hydrogenation at 100 to 300 atmospheres in a liquefaction reaction tower, and gas,
Light oil, solvent fraction, and solid content are separated, and the pressure is further reduced in a low-pressure separation tower, and the liquefied product is separated into solid content such as solvent, liquefied oil, ash, and unreacted carbon (hereinafter referred to as r residue J) in a solid-liquid separation process. )
Separate into two parts. Here, as the solid-liquid separation step, there are methods of separating a liquid component and a solid component by distillation, centrifugation, etc. depending on the subsequent use, but a vacuum distillation column is usually adopted for ease of industrialization.

As is well known, this vacuum distillation column is a device that distills and refines high-boiling fractions at a temperature below the decomposition temperature by distilling under reduced pressure, and is especially essential for loading and recovering coal-based and petroleum-based fuels. belongs to.

When this vacuum distillation is used in the coal liquefaction method, the liquefied product, catalyst, and ash are inserted into a distillation column in the form of a slurry.
Remove the remaining pickle from the bottom of the tower. This residue contains unreacted coal and a considerable amount of ash, and thermal alteration also occurs, so the ability to extract the residue from the bottom of the column has a large effect on the yield of liquefied oil. .

Here, the ability to extract the residue from the vacuum distillation column is determined by the viscosity of the residue. Normally, there are no pumps that can be used industrially for viscosity of 50 boids or more, so it is necessary to maintain the temperature at the bottom of the column within an appropriate range in order to maintain the viscosity below that value. In this way, the viscosity of the residue is deeply involved in the quality of the extractability of the residue, and the viscosity of the residue is determined by temperature and properties of the residue (heptane soluble content (H3), toluene soluble content (TS).
), quinoline soluble content (QS), ash content, etc.). Regarding temperature dependence, it is known that there is a linear relationship between the logarithm of viscosity and the reciprocal of temperature (absolute temperature). There is the inconvenience of having to measure the viscosity while changing the temperature, and depending on the type of coal, it is necessary to leave the high-boiling fraction in the residue to lower the viscosity of the residue and extract it.

(Problems to be Solved) The purpose of this invention is to use a relatively simple device to enable extraction of liquefied residue under the maximum load condition of the vacuum distillation column (538°C cut in terms of normal pressure). It is an object of the present invention to provide a method for evaluating the properties of the liquefied residue of each type of raw coal in advance and improving the properties of the residue so as to lower the viscosity of the residue.

(Means for Solving the Problems) The present inventors have conducted various studies in order to achieve the above object. First, in order to examine whether it is possible to easily investigate the properties of liquefaction residue, we investigated the relationship between viscosity and the reciprocal of temperature, which is used to evaluate the ability to extract various liquefaction residues in a conventional continuous coal liquefaction unit (large size). When the experimental data of an autoclave apparatus and the data of a small continuous apparatus using a pseudo-solvent were plotted in the figure, it was found that they lie almost on the same straight line as shown in FIG. In other words, if you want to investigate the properties of liquefied residue, you can conduct a liquefaction experiment using a relatively simple device such as an autoclave, and use the distillation residue to create a viscosity-temperature correlation diagram. We found that it is possible to estimate the viscosity of

Therefore, it was determined that by investigating the properties of the distillation residue of each coal type using an autoclave device, it would be possible to estimate the viscosity of the residue from the liquefaction plant and evaluate the extractability of each coal type. Therefore, the results of investigating the properties of the liquefied residue for each coal type (A-C) are shown in FIG. In Figure 2, the horizontal axis shows the softening point of the residue, and the vertical axis shows the pour point of the residue, but for coal type C, there is no pour point under the maximum load condition of the vacuum distillation column, and viscosity measurement is difficult. An impossible situation has been reached.

Therefore, it is necessary to reduce the viscosity of such coal by lowering the load on the vacuum distillation column.

I just conducted a J4 survey on the properties of the residue for coal type C.
It was found that the ash content and TS greatly affected the viscosity of the residue.

Therefore, we performed deashing treatment on coal type C, created coals with various persimmon ash contents, and conducted liquefaction experiments in an autoclave apparatus to measure the softening point and pour point of the distillation residue, and found that the ash content of the liquefied residue was It was found that when it exceeds 40%, a softening point exists, but a pour point no longer exists. This has an ash content of 40
% or more, the liquefaction residue lost its uniformity, and the clay content was measured and it was determined that this was due to an abnormally high pour point.

On the other hand, when we investigated the relationship between viscosity and temperature using the liquefied residue of coal (B and C) whose ash content was deashed to the same level as conventional coal, we found that
The results shown in the figure were obtained, and although coal types B and C had almost the same ash content, the viscosity of coal type C was higher than m, and it was found that the extractability of the residue could not be evaluated based on the ash content alone. . Therefore, as a result of investigating the properties of the above sample, it was found that the TS content was lower than that of conventional charcoal residue. Therefore, in order to improve the extractability of the liquefied residue, it is necessary to consider not only the ash molecular chain but also the TS fraction in the residue.

That is, when we conducted a liquefaction experiment with qt German coal type B, we attempted to mix BR type, which has a relatively low viscosity, with c4 type, and found that
As shown in the figure, it has been found that it is possible to increase the TS content and lower the pour point of C coal type.

In general, the temperature at the bottom of the distillation column is said to be 350°C or less from the viewpoint of rapid thermal deterioration of the liquefied residue and the maximum load of the distillation column. The highest pour point of the residue is assumed to be around 230"C based on the viscosity that can be extracted from the pump in Figure 3. Therefore, from the relationship between the properties of the residue and the pour point in Figure 4, the TS in the residue is 30".
% or more is required.

As described above, in order to maintain the maximum load on the vacuum distillation column and improve the ability to extract the liquefied residue, the use of mixed charcoal is a good means. It was found that it is sufficient to mix the ingredients so as to satisfy 2).

ASH=(Σxi ASH, φ1)/(ΣX, φi)≦
0.4---- (1) Ts= (r, x, ``rs
t<61)/(ΣXtφ1゛)≧0.3---
(2) Here, xl: residue yield of each coal type (-)TS,
: TS fraction in the residue of each coal type (%) ASH, : Ash content in the residue of each coal type (%) φ1 : Mixing ratio of coal types (-) In other words, the gist of the present invention is that each The properties of the coal liquefaction residue when using a single coal type are evaluated in advance using a simple experimental device (such as an autoclave), and the coal type is adjusted so that the ash content and the amount extracted by an appropriate solvent are within the limit range. This is a coal liquefaction method characterized by adjusting the blend.

Next, the present invention will be specifically explained with reference to Examples.

(Example 1) Using coal liquefaction equipment with a coal throughput of 40 kg/d, the first
Liquefaction reaction temperature 4 for each coal type A and B shown in the table
Table 2 shows the properties of the liquefied residue obtained by liquefying the product under the conditions of 50° C. and 170 atm reaction pressure, and distilling the liquefied product at the maximum load of the vacuum distillation column (538° C. cut in terms of normal pressure).

As a result, coal types A and B can be sufficiently extracted from the bottom of the distillation column.

(Example 2) Using coal liquefaction equipment with a coal throughput of 1 t/d, coal type C shown in Table 3 was liquefied under conditions of a liquefaction reaction temperature of 450°C and a reaction pressure of 170 atm, and the product after liquefaction was As a result of operating the vacuum distillation column near its maximum load (500°C cut in terms of normal pressure), the pump at the bottom of the distillation column malfunctioned, making it impossible to extract the liquefied residue. Thereafter, the load on the distillation column was lowered and the distillation was taken out, and when the operation was about to end, the distillation column was operated again near the maximum load. Table 4 shows the results of investigating the properties of the products accumulated in the distillation column.

(Example 3) Using a coal liquefaction facility with a coal throughput of 40 kg/d, 50 kg of coal types B and C shown in Tables 1 and 3 were each used.
% and liquefaction reaction temperature 450" C1 reaction pressure 170
Table 5 shows the properties of the liquefied residue obtained by liquefying the product under atmospheric pressure and distilling the liquefied product near the maximum load of the vacuum distillation column (538° C. cut in terms of normal pressure). As a result, by blending B coal type, it became possible to extract C coal type under the highest load condition of the distillation column.

Table 5 In addition, the residue yield and properties of the residue for each coal type m taste by the autoclave device are as shown in Table 6, (1), (
2) ASHI and T of coal type B+C calculated from the formula
Srd was 32% and 35%, which were almost the same as the examples shown in Table 5.

(Effects of the Invention) According to the present invention, by investigating the properties of liquefied residue from each type of coking coal in advance using a simple device,
Trouble in the vacuum distillation column can be completely prevented and efficient coal liquefaction can be achieved.

[Brief explanation of drawings]

FIG. 1 is a viscosity-temperature correlation diagram of liquefied residual material obtained when changing the liquefaction device. FIG. 2 is a correlation diagram of the softening point and pour point of liquefied residue for coal types A to C. FIG. 3 is a viscosity-temperature correlation diagram of liquefied residues for Sumigami B and C whose ash content was adjusted to 31% to the same level as conventional coal. FIG. 4 is a diagram showing how the pour points of liquefied residues in blended coals of coal types B and C are lowered.

Claims (2)

[Claims] (1) Evaluate the properties of coal liquefaction residue when using each type of coal in advance using a simple experimental device (such as an autoclave), and make sure that the ash content and extractables with an appropriate solvent are within the limits. , a coal liquefaction method characterized by adjusting the blend of coal types. (2) Ash content in the residue ≦0.4, toluene soluble content ≧0.
3. The coal liquefaction method according to claim (1), wherein the blend of coal types is adjusted so that the amount of coal is liquefied.