JPH0128078B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for pre-treating coking coal for coal liquefaction. More specifically, the present invention relates to a method for pre-treating coking coal for coal liquefaction, including pulverization, deashing, and dehydration of coal.

Recently, coal liquefaction technology has been actively researched as a measure to cope with the depletion of oil resources. However, since coal is solid, it needs to be crushed before use, and since it contains a lot of ash, it needs to be removed as much as possible.Moreover, moisture adhering to coal reduces the performance of coal liquefaction plants. Therefore, it is necessary to remove it.

The inventors of the present invention have carried out intensive studies to interpret these problems in a technically and economically advantageous manner, and as a result, have completed the present invention which solves the above problems and is also capable of mass processing.

That is, the present invention provides at least one type of water selected from coal, light oil, wastewater from the flotation separator process in this process, wastewater from the oil-water separator in this process, wastewater from the coal liquefaction process, and make-up water. The slurry is crushed and then introduced into a flotation separator to be separated into a deashed coal stream and an ash stream, and heavy oil is mixed with the deashed coal stream. Then, the mixed oil is introduced into a separator and separated into wet heavy oil and a slurry of deashed and dehydrated coal and heavy oil, and then the wet heavy oil is separated into water and heavy oil in an oil-water separator. death,
The separated water is used for coal water slurry.
This is a pretreatment method for coking coal for coal liquefaction, which is characterized by adding a portion of the separated heavy oil to a slurry of deashed and dehydrated coal and heavy oil.

Normally, coal is brought to a coal liquefaction plant after it has been subjected to ordinary coal cleaning and has been deashed to some extent. However, if the coal liquefaction plant is close to a coal mine, the coal is brought in unwashed, and in this case the normal coal washing method is carried out, but the coal is generally washed in lumps, so the particle size after washing is The distribution is quite wide. The present invention targets coal having a wide particle size distribution as raw coal for liquefaction.

Next, the present invention will be explained based on one embodiment shown in FIG.

Coking coal, light oil, and water are charged into a water slurry tank 1 to form a slurry and sent to a wet crusher 2. When grinding a slurry consisting of coking coal, light oil, and water, the smaller the particle size of the coal, the easier it is to separate the ash, but on the other hand, the smaller the particle size, the more burden is placed on the grinder and transport of the slurry. It is preferable to crush it to about 1 mm or less. In addition, wet pulverization in water as in the present invention has the advantage that the power cost required for pulverization is low and the components can be separated easily.

Next, the slurry of pulverized coal, light oil, and water is introduced into the flotation separator 3 and separated into a deashed coal stream a and an ash stream b, and the stream a is dehydrated by the coal belt filter 4 and becomes heavy It is mixed with heavy oil in an oil mixing tank 6 and sent to a centrifuge 7. The heavy oil to be mixed here is preferably heavy oil having a boiling point of 250° C. or more and a specific gravity of 1 or more produced in the coal liquefaction step and/or heavy oil d separated in the oil-water separator of this step. The separator 7 may use either a natural sedimentation method or a pressure dehydration method in which natural sedimentation is performed at a temperature of 100 to 200°C under the saturated vapor pressure of water at that temperature, but in the present invention, water is removed by the difference in specific gravity. Adopt a centrifuge. In this case, there are many advantages such as no need for a pressure vessel, large-scale processing possible, water removal without evaporation, no need for latent heat of vaporization, and advantageous thermal efficiency.

The coal and heavy oil slurry discharged from the centrifuge 7 is mixed with heavy oil d from the oil-water separator 9 in a coal and heavy oil slurry tank 10 to become raw coal for the coal liquefaction process. In addition, the flow c of the water-containing heavy oil separated by the separator 7
passes through a water-containing heavy oil heater 8 and reaches an oil-water separator 9 where it is separated into a heavy oil stream d and a wastewater stream e, and the heavy oil is sent to a heavy oil mixing tank 6 and/or a coal heavy oil slurry tank. 10 cycles. Further, the waste water e separated in the oil-water separation tank 9 is sent to the water slurry tank 1 together with the waste water e from the coal belt filter 4 and the ash belt filter 5, and used for producing coal water slurry.

The oil/water separator 9 can use the natural sedimentation method, centrifugation method, etc. as with the separator 7, but it is possible to use water-containing heavy oil at 100℃ or higher.
The pressurized dehydration method, in which water is heated to a temperature of 200°C and a pressure higher than the vapor pressure of water at that temperature and allowed to settle naturally, is advantageous in terms of equipment costs, maintenance costs, etc.

Water slurry tank 1 uses wastewater from the oil-water separator in this process and wastewater from the coal liquefaction process, but these wastewaters contain hydrocarbon oil, which is part of the flotation agent. Not only can it be used as a fuel, but most of it adheres to the coal, so waste water from coal belt filters and ash belt filters can be easily treated.

In addition, in a flotation separator, iron sulfide in the coal component, which is known to be a good catalyst during coal liquefaction, floats together with the coal and is not removed. This can be said to be an extremely advantageous method.

The present invention will be explained in more detail below using examples, but is not limited thereto.

Example 1 Coal with a raw coal ash content of 36% was cut using a water jig whose specific gravity was adjusted to 1.8 to reduce the ash content to 18% and adhering moisture.
Raw coal was obtained after 10% primary coal washing. The raw coal is mixed with waste water from the flotation separator process and oil-water separator process, waste water from the coal liquefaction process, and 5wt% of light oil with a boiling point of 250°C or less produced in the coal liquefaction process based on the weight of the raw coal. A water slurry with a raw coal concentration of 10% was obtained. This water slurry was passed through a disc-type wet mill and placed in a flotation separator to float the coal and remove the ash from the bottom. The coal content was easily dehydrated using a belt filter to obtain deashed coal with an ash content of 11% and moisture content of 30%. When the ash was dehydrated using a belt filter, the moisture content was 40% and the ash content was 82%. On the other hand, the water discharged from each belt filter contained less than 10 ppm of oil and less than 50 ppm of phenol, and had physical properties that could be discharged as is, depending on the situation. The deashed coal was mixed and stirred with heavy oil with a boiling point of 250°C or more and a specific gravity of 1.05 produced in the coal liquefaction process, and then passed through a continuous centrifuge at 1000G for 5 minutes, resulting in 70% coal and moisture on the sludge side. 4.2%, oil content 25.8% coal,
Heavy oil slurry and coal 1.7%, moisture 8.3%, oil content
A 90.0% water-containing heavy oil was obtained. Next, add water-containing heavy oil.
Introduced into an oil-water separator maintained at 120℃ and 3Kg/cm ² G, the water content is 95.1%, SS content is 0.4%, and oil content is 4.4% from the top.
1.0% moisture, 1.8% SS content, and oil content from the bottom.
97.2% heavy oil was obtained. 65% of this heavy oil was mixed with coal and heavy oil slurry to make raw material slurry for coal liquefaction, and 35% was recycled and reused in the heavy oil mixing tank. The wastewater from the upper part of the oil-water separator was circulated to a water slurry tank and used for slurrying coal.

[Brief explanation of drawings]

FIG. 1 shows a flow sheet of one embodiment of the present invention. In the figure: 1... water slurry tank, 2... wet crusher, 3... flotation separator, 4... belt filter for coal, 5... belt filter for ash, 6
...Heavy oil mixing tank, 7...Centrifugal separator, 8...Water-containing heavy oil heater, 9...Oil-water separator, 10...Coal, heavy oil slurry tank, a...Deashed Flow of coal, b...Flow of ash, c...Flow of hydrous heavy oil, d...Flow of heavy oil, e...Flow of wastewater.

Claims (1)

[Claims] 1. At least one type selected from coal, light oil, wastewater from the flotation separator process in this process, wastewater from the oil-water separator in this process, wastewater from the coal liquefaction process, and make-up water. Mix with water to make a water slurry,
After crushing, the slurry is introduced into a flotation separator and separated into a deashed coal stream and an ash stream, and heavy oil is mixed with the deashed coal stream and the mixed oil is introduced into the separator. The water-containing heavy oil is separated into a slurry of deashed and dehydrated coal and heavy oil.The water-containing heavy oil is then separated into water and heavy oil in an oil-water separator, and the separated water is separated into coal water. A method for pretreating coking coal for coal liquefaction, which is used as a slurry and is characterized by adding a part of the separated heavy oil to a slurry of deashed and dehydrated coal and heavy oil. 2. The pretreatment method according to claim 1, wherein the light oil mixed with the coal is a hydrocarbon oil with a boiling point of 250° C. or less and is 0.5 wt% to 5.0 wt% based on the raw coal. 3. The pretreatment method according to claim 1 or 2, wherein a slurry of coal, light oil, and water is pulverized so that the particle size of the coal is 1 mm or less. 4. Claim 1, in which the heavy oil mixed with the deashed coal stream is heavy oil with a boiling point of 250°C or higher and a specific gravity of 1 or higher, and/or heavy oil separated by an oil-water separator in this process. The preprocessing method for any one of the above, the second term, and the third term. 5. Claim 1, wherein the separator for separating the mixture of deashed coal stream and heavy oil into water-containing heavy oil and a slurry of deashed and dewatered coal and heavy oil is a centrifuge. Pretreatment method described in section. 6. The pretreatment method according to claim 5, wherein the oil-water separator for separating water-containing heavy oil into heavy oil and water is a centrifuge. 7 The oil-water separator that separates water-containing heavy oil into heavy oil and water is a separator that uses a natural sedimentation method at a temperature of 100°C to 200°C and a pressure higher than the saturated vapor pressure of water at that temperature. The pretreatment method according to scope item 5.