JPS63207891A - Liquefaction of coal - Google Patents

Abstract

PURPOSE:To remove a formed product attached to a preheater, etc., without stopping operation and to stably liquefy coal in high efficiency, by alternately using a sulfur-containing iron oxide catalyst and a pyrite catalyst at fixed time intervals. CONSTITUTION:Coal slurry consisting of (A) coal, (B) a solvent such as creosote oil, anthracene oil, etc., and (C) an iron oxide catalyst blended with sulfur as a promoter and a hydrogen gas are pressurized, sent to a preheater and the preheated slurry and the hydrogen gas are sent to a liquefying reactor. After a given time (e.g. 36hr) is passed, coal slurry consisting of the components A and B and (D) a synthetic or natural pyrite catalyst is sent instead of the above-mentioned slurry to the preheater for a given time (e.g. 36hr) and a formed product attached to the preheater, etc. is removed. Then again, the slurry of the former is made to flow and the two kinds of the slurries are alternately sent to the preheater at intervals of given time to liquefy coal.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a method for liquefying coal.

[Conventional technology]

Coal liquefaction is generally carried out by feeding a coal slurry consisting of coal, a solvent, and a catalyst under pressure into a preheater together with hydrogen gas, and then preheating the coal slurry and hydrogen gas to a reaction temperature or a temperature close to it in the preheater. It is carried out by sending preheated coal slurry and hydrogen gas to a reactor, and further adding hydrogen gas in the reactor to liquefy it.

The catalyst used for coal liquefaction increases the liquefaction efficiency of 1 coal,
It is used to relax the liquefaction reaction conditions.

The catalyst is preferably one that has high liquefaction activity, is inexpensive, and can be obtained in large quantities. Therefore, catalysts in which sulfur is added as a promoter to iron oxide catalysts such as iron ore, iron oxides, and iron compounds are generally used.

[Problem that the invention seeks to solve]

However, when the above-mentioned iron oxide catalyst (for example, red mud, laterite, etc.) is used as a catalyst and sulfur as a co-catalyst, the following problems occur. That is, under high temperature and high pressure (for example, 100 to 250 KW/(, m'G).

300 to 450°C) and in the presence of hydrogen, a solid substance mainly composed of billotite and troilite is generated, and this product is not only in the preheater but also in the preheater and reactor. It grows by adhering to the connecting conduit and the inner wall of one reactor.

As a result, the pressure loss within the preheater and within the reactor cylinder increases, leading to disturbances in the flow of the coal slurry and destabilization of the operation. Furthermore, if the adhered products grow significantly, coking will occur with the products as nuclei, so the operation should be temporarily stopped.

It becomes necessary to clean the inner walls of the preheater, reactor, etc. by mechanical or chemical methods.

Therefore, it is an object of the present invention to generate a preheater in a preheater.

To provide a coal liquefaction method capable of highly efficient coal liquefaction through stable operation by removing products adhering to a preheater reactor and conduits connecting these without stopping the operation. There is a particular thing.

[Means for solving problems]

This invention includes the following steps: 1. Pressurizing a coal slurry consisting of coal, a solvent, and a catalyst, and hydrogen gas and sending it to a preheater;
a step of preheating both the coal slurry and the hydrogen gas in the preheater to a liquefaction reaction temperature or a temperature close to this; and transferring both the coal slurry and the hydrogen gas preheated in the preheater from the preheater to a reactor. In the method for liquefying coal, the coal slurry is liquefied in the reactor;
It is characterized by using the tsquirite catalyst alternately at regular intervals.

In this invention, the reason why the pyrite catalyst is used alternately with the iron oxide catalyst at regular intervals is as follows. In other words, pyrite catalysts have the property of removing products that adhere to the inside of the preheater, etc., so by using iron oxide catalysts, it is possible to remove the products that adhere to the inside of the preheater without interrupting operation. .

This is because stable operation can be carried out over a long period of time.

Synthetic pyrite or natural pyrite is used as the pyrite catalyst. Synthetic pyrite is synthesized to obtain high liquefaction properties.

Synthesis 7′! ? Representative examples of the chemical compositions of illite and natural pyrite are shown in Table 1.

The amount of the catalyst shown in Table 1 added is preferably within the range of 2 to 10 parts by weight per 100 parts by weight of coal. However, if the amount of the catalyst added is less than 21 parts by weight, the desired effect cannot be obtained, while if the amount added exceeds 10 parts by weight, no improvement in the effect in terms of μ can be obtained.

The concentration of coal in the coal slurry is 20-45%.

In particular, it is preferably within the range of 30 to 40%.

This is because if the concentration of Kakedashi 1 coal is less than 20%, the amount of solvent in the coal slurry is too large and the liquefaction efficiency decreases, and if it exceeds 45%, the viscosity of the coal slurry increases, making it unfavorable for handling.

Preheating of coal slurry @ degree is 300~480℃, especially 35
It is preferably within the range of 0 to 450°C. However, if it is less than 300°C, there is a large difference in temperature between the coal slurry and the reactor to which it is sent next, resulting in poor thermal efficiency.
This is because coking will occur if the temperature exceeds ℃.

The temperature of the coal slurry in the reactor is 350-480°C.

In particular, it is preferably within the range of 410 to 470°C.

However, the reaction efficiency is poor below 350°C.
This is because if it exceeds C, caulking will occur.

The pressure of the stream consisting of coal slurry and hydrogen gas in the preheater and reactor is 100 to 350 K.
It is preferable to fall within the range of g/JG.

However, if it is less than 100Kp/iG, the liquefaction efficiency is poor.

This is because exceeding 350 K9/caG is unfavorable in terms of pump performance and handling.

As the solvent, anthracene oil, creosote oil, coal liquefied oil, or a mixture thereof can be used.

As the hydrogen gas, hydrogen gas alone or a gas mainly composed of hydrogen gas can be used.

FIG. 5 is a process diagram showing an outline of a coal slurry preheating device in a coal liquefaction device.

As shown in FIG. 5, 1 coal slurry preheating device (hereinafter referred to as this device) includes a storage tank 1 for storing coal slurry,
A high-pressure slurry pump 2 provided in the middle of a conduit 15 for pressurizing the coal slurry discharged from the storage tank 1 and sending it to a first preheater 4 to be described later, and a tank for pressurizing hydrogen gas and sending it into the coal slurry. , a hydrogen gas compressor 3 provided in the middle of a hydrogen gas conduit 16, a first preheater 4 and a second preheater 5 for preheating the coal slurry and the hydrogen gas, and a first preheater. 4 and a heat exchanger 6 for cooling the coal slurry and hydrogen gas preheated by the second preheater 5, and a gas-liquid separator for separating the coal slurry cooled by the heat exchanger 6 from the hydrogen gas. It consists of 7. Separated coal slurry and hydrogen gas are
Then, it is sent to a post-processing device such as a reactor (not shown) and processed. This apparatus configured as described above is equipped with a set of equipment necessary for preheating coal slurry at high temperature and high pressure.

As the preheater, a normal preheater or a heat exchanger type preheater can be used.

Next, the present invention will be explained using examples and comparing with comparative examples.

[Comparative example]

Coal was liquefied by the method described below using a coal liquefaction apparatus including the present apparatus shown in FIG.

100 parts by weight of coal (Pacific coal) with the chemical composition shown in Table 2, 233 parts by weight of anthracene oil as a solvent, and 4 parts of red mud with the chemical composition and particle size shown in Table 3 as a catalyst.
．． 2 parts by weight and 0.8 parts by weight of sulfur,
Coal slurry IJ+ with a concentration of 30% (concentration of 31.1% as the total amount of slurry) was prepared.

The coal slurry is transferred from the storage tank 1 shown in FIG.
6 and conduit 15 to 7.5Nrr? Both are fed under pressure to the first preheater 4 and the second preheater 5 at a flow rate of /hour. The temperature of the coal slurry is 300 at the outlet of the first preheater 4.
The temperature was adjusted to 300°C at the inlet of the second preheater 5 and 480°C at the outlet of the second preheater 5, and the pressure was adjusted to maintain 250 Kg/mG at the outlet of the second preheater 5. . As the preheating coil of the second preheater 5, a SUS 316 stainless steel pipe with an inner diameter of 4 m and a length of 10 m was used.

Under these conditions, the coal slurry was poured into this device and heated for 36 minutes.
Operated for hours.

At the inlet and outlet of the second preheater 5 during operation of this device,
The pressure of the coal slurry that is fed under pressure with hydrogen gas is measured, and the pressure difference between the inlet and outlet is measured.

That is, FIG. 6 shows the relationship between pressure loss ΔP and operating time.

As shown in FIG. 6, as the operating time elapses, the pressure loss between the inlet and outlet of the second preheater 5 increases;
8 after 6 hours. OKf/! It became. At this time,
The results of observing the inner surface of the preheating coil 8 by cutting the preheating coil 8 of the second preheater 5 shown in FIG. 7 at the locations indicated by numbers (1) to (9) in the figure.

The product was uniformly attached to the inner wall of the preheating coil 8. 1
0 is the coal slurry outlet, and 1) is the coal slurry population. Particularly at the first stage of the preheating coil 8 near the coal slurry outlet 10, that is, at the position indicated by number (1) in FIG. 7, where the temperature of the slurry reaches up to 480°C.

As shown in the enlarged view of the cut section of the preheating coil in FIG.

Adhesion of product 9 with a thickness of 0.7 g was confirmed. 12 is an outer wall surface, 13 is an inner wall surface, and 14 is an embedded resin.

[Example 1] Coal was liquefied by the method described below using a coal liquefaction apparatus including the present apparatus shown in FIG.

100 parts by weight of coal (Pacific coal) with the chemical composition shown in Table 2, 233 parts by weight of anthracene oil as a solvent, and 4 parts of red mud with the chemical composition and particle size shown in Table 3 as a catalyst.
．． 2 parts by weight and 0.8 parts by weight of sulfur,
Coal slurry with a concentration of 30% (concentration of the total amount of slurry was 31.1%) was prepared.

Then, the coal slurry was passed through the apparatus under the same conditions as in the comparative example, and the apparatus was operated for 36 hours.

Then, instead of red mud and sulfur as catalysts.

A coal slurry prepared at a concentration of 30% by adding 5 parts by weight of synthetic pyrite having the chemical composition and particle size shown in Table 3 was passed through the apparatus for an additional 36 hours, and the apparatus was operated for a total of 72 hours.

At the inlet and outlet of the second preheater 5 during operation of this device,
The pressure of the coal slurry that is fed under pressure with hydrogen gas is measured, and the pressure difference between the inlet and outlet is measured.

That is, FIG. 1 shows the relationship between pressure loss ΔP and operating time.

After 72 hours of operation using this device, the product remaining and adhering to the preheating coil 8 of the second preheater 5 was scraped from each position, and the amount of adhesion at each position was measured. the second
It is indicated by a solid line A in the figure. In FIG. 2, the broken line shows the amount of product deposited on the preheating coil 8 after 36 hours of operation using red mud and sulfur as catalysts, and the solid line B shows the amount of product deposited on the preheating coil 8 together with hydrogen gas under pressure. Coal slurry IJ
+ temperature changes are shown continuously for each position of the preheating coil 8.

As is clear from Figure 1, the pressure loss when using red mud and sulfur as catalysts is 8. However, after replacing the catalyst from red mud and sulfur with synthetic pyrite, the pressure drop gradually decreased to 4.81' l/i at the end of the run.

As is clear from FIG. 2, the amount of product deposited was significantly reduced compared to when 36 hours had passed using red mud and sulfur as catalysts.

[Example 2] Coal was liquefied by the method described below using a coal liquefaction apparatus including the present apparatus shown in FIG.

100 parts by weight of coal (Pacific Coal) having the chemical composition shown in Table 2, 233 parts by weight of anthracene oil as a solvent, and 4 parts of red mud with the chemical composition and particle size shown in Table 3 as a catalyst.
．． 2 parts by weight and 0.8 parts by weight of sulfur,
Coal slurry with a concentration of 30φ (concentration of 31.1% as the total amount of slurry) was prepared.

Then, the coal slurry was passed through the apparatus under the same conditions as in the comparative example, and the apparatus was operated for 36 hours.

Next, in place of the red mud and sulfur as a catalyst, 5 parts by weight of natural tsquirite having the chemical composition and particle size shown in Table 3 was added to make the coal slurry have a concentration of 30%, and one coal slurry was poured into the apparatus for an additional 36 hours. 1 It was operated for a total of 72 hours.

At the inlet and outlet of the second preheater 5 during operation of this device,
The pressure of the coal slurry that is fed under pressure with hydrogen gas is measured, and the pressure difference between the inlet and outlet is measured.

That is, FIG. 3 shows the relationship between pressure loss ΔP and operating time.

After 72 hours of operation using this device, the product remaining and adhering to the preheating coil 8 of the second preheater 5 was scraped from each position, and the amount of adhesion at each position was measured. The fourth
It is indicated by a solid line A in the figure. In FIG. 4, the broken line shows the amount of product deposited on the preheating coil 8 after 36 hours of operation using red mud and sulfur as catalysts, and the solid line B shows the amount of product deposited on the preheating coil 8 together with hydrogen gas under pressure. Changes in the temperature of the coal slurry introduced are shown continuously for each position of the preheating coil 8.

As is clear from Figure 3, the pressure loss increased to 8.0 Kg/Ca when red mud and sulfur were used as catalysts, but the pressure drop after replacing red mud and sulfur with natural pyrite as catalysts The loss gradually decreased to 4.6 kg/- at the end of the operation.

As is clear from FIG. 4, the amount of product deposited is .

This was significantly reduced compared to the 36 hour period when red mud and sulfur were used as catalysts.

〔Effect of the invention〕

μ As mentioned above, the products deposited by using red mud and sulfur as catalysts then.

Significant removal was achieved by using synthetic or natural pyrite as a catalyst, which also resulted in a significant reduction in pressure drop.

Synthetic pyrite and natural pyrite both exhibited high adhesion product removal effects when used as catalysts, resulting in highly stable coal liquefaction operations.

Although pyrite catalysts are more expensive than conventional catalysts made of iron oxide catalysts such as red mud and laterite, and sulfur, they can be used alternately with these conventional catalysts to reduce the cost of coal. Liquefaction operation becomes possible.

As described above, according to the method of the present invention, an inexpensive iron oxide catalyst and sulfur can be used as catalysts for coal liquefaction, and stable coal liquefaction operation can be performed continuously for a long time. 1. An industrially useful effect is brought about in which coal liquefaction is performed with high efficiency and low cost.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the pressure loss of the second preheater in Example 1, and FIG. 2 is a diagram showing the amount of product deposited on the preheating coil.
FIG. 3 is a diagram showing the pressure loss of the second preheater in Example 2, and FIG. 4 is a diagram showing the amount of product deposited on the preheating coil.
FIG. 5 is a process diagram showing an overview of the coal slurry preheating device, FIG. 6 is a diagram showing the pressure loss of the second preheater in a comparative example,
FIG. 7 is a schematic view of the second preheater, and FIG. 8 is an enlarged view of a cut section of the preheating coil. In the drawing. 1...Storage tank, 2...High pressure slurry pump. 3... Hydrogen gas compressor, 4... First preheater. 5...Second preheater, 6...Heat exchanger. 7... Gas-liquid separator, 8... Preheating coil. 9...Product, 10...Coal slurry outlet. 1) Coal slurry population, 12... External wall surface. 13...Inner wall surface, 14...Embedded resin. 15.16... Conduit.

Claims (9)

[Claims] (1) Coal slurry consisting of coal, solvent, and catalyst;
a step of pressurizing hydrogen gas and sending it to a preheater; a step of preheating both the coal slurry and the hydrogen gas to a liquefaction reaction temperature or a temperature close to this in the preheater; A coal liquefaction method comprising the steps of feeding the coal slurry and hydrogen gas together from the preheater to a reactor, and liquefying the coal slurry in the reactor, wherein sulfur as the catalyst A method for liquefying coal, characterized in that an iron oxide-based catalyst to which is added and a pyrite-based catalyst are used alternately at regular intervals. (2) The method for liquefying coal according to claim (1), wherein the pyrite is synthetic pyrite. (3) The method for liquefying coal according to claim (1), wherein the pyrite is natural pyrite. (4) The method for liquefying coal according to claim (1), wherein 2 to 10 parts by weight of a catalyst is added to 100 parts by weight of coal. (5) The coal liquefaction method according to claim (1), wherein the preheating temperature of the coal slurry is in the range of 300 to 480°C, and the reaction temperature in the reactor is in the range of 350 to 480°C. (6) Increase the pressure in the preheater and reactor to 100-35
Claim No. 1 (1) which is in the range of 0Kg/cm^2G
) The coal liquefaction method described in section 2. (7) The method for liquefying coal according to claim (1), wherein creosote oil, anthracene oil, coal liquefied oil, or a mixed oil thereof is used as the solvent. (8) The method for liquefying coal according to claim (1), wherein the hydrogen gas is hydrogen gas alone or a gas mainly composed of hydrogen gas. (9) The coal liquefaction method according to claim (1), wherein a normal preheater or a heat exchanger type preheater is used as the preheater.