JPH03181593A - Method for liqefying coal - Google Patents

Abstract

PURPOSE:To stably and efficiently carry out separation of liquefied residue and improve yield of liquefied producing oil by previously centrifuging coal liquefied slurry and feeding a component reduced in ash to a distillation tower. CONSTITUTION:A coal liquefied slurry is centrifuged and then a component reduced in ash is fed to a distillation tower, where the component is separated into liquefied producing oil having <=538 deg.C boiling point and liquefied residue having 20-35wt.% ash content. Furthermore, preferably, water produced in liquefaction reaction process is added to a component containing much ash after centrifugation of liquefied slurry and the slurry is re-centrifuged and the component reduced in ash after centrifugation is re-circulated to liquefaction process.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for liquefying coal to improve the yield of liquefied oil. The present invention also relates to a coal liquefaction method that can be carried out efficiently.

Conventional technology The coal liquefaction process includes a liquefaction reaction step to liquefy coal, a solid-liquid separation step to separate slurry liquid and residue from the liquefied product, and hydrogen addition to a part of the liquefied oil. A solvent suitable for liquefaction.

It consists of a reforming solvent hydrogenation process.

In the liquefaction reaction step, coal, a liquefaction promoting catalyst, and a liquefaction solvent whose main components are liquefied oil are supplied, and the coal is liquefied under hydrogen pressure.

In the solid-liquid separation step, the slurry after gas and water have been separated from the liquefied product is separated into a liquid and a residue, and the liquid is further separated and a portion is recycled and used as a liquefaction solvent.

In the solvent hydrogenation step, the liquefaction solvent and the hydrogenation promoting catalyst are supplied, and hydrogen is added to the liquefaction solvent under hydrogen pressure to reform the liquefaction solvent into properties suitable for liquefaction.

It is desirable that such a coal liquefaction process be applicable to a wide range of coals, as the construction cost is high and it is difficult to secure a large amount of coal for the process using one type of coal. It will be done.

Furthermore, in the coal liquefaction process, it is necessary to safely and efficiently separate the liquefaction residue in the solid-liquid separation step in order to improve the yield of liquefied oil.

Conventionally, filtration, gravity sedimentation, centrifugation, etc. have been used as solid-liquid separation methods, but filtration methods have problems with filtration speed and filter clogging, while gravity sedimentation methods have problems with sedimentation speed and separation efficiency. Both centrifugal separation methods have not been put into practical use because they do not solve the problem of separation efficiency.

For this reason, a distillation method is generally used as a solid-liquid separation method.

Problems to be Solved by the Invention In the distillation method adopted as a solid-liquid separation method for liquefied slurry, it is necessary to mix some liquefied product oil into the liquefied residue in order to ensure the fluidity of the residue extracted from the bottom of the distillation column. be.

In particular, when liquefying coal that has a high ash content and produces a small amount of liquefied residue, the ash content of the residue extracted from the bottom of the distillation column is 35% by weight.
If the temperature exceeds this level, the fluidity will drop significantly, forcing operation to reduce the separation efficiency of the distillation column and mix a large amount of liquefied oil into the liquefied residue, resulting in the problem of a decrease in the yield of liquefied oil. have

As a method to solve this problem, the ash content of the coal is removed by specific gravity separation etc. before supply to the liquefaction process, or the ash content in the liquefied slurry is removed by centrifugation etc. prior to distillation and the residue is removed from the bottom of the distillation column. There are ways to improve sex.

However, the method of removing ash from coal requires new equipment with a processing capacity greater than the amount of coal supplied to the process, and the method of removing ash from liquefied slurry requires
In both cases, it has been difficult to perform stable and efficient separation operations for a wide range of coals, as the loss of liquefied oil during centrifugation operations is large.

In view of these circumstances, this invention was developed to solve the problem of the method of reducing the ash content in the liquefied slurry by centrifugation prior to distillation and introducing it into the distillation column. This paper attempts to propose a coal liquefaction method in which the yield of liquefied oil can be improved by a two-stage solid-liquid separation method that enables separation operations.

Means for Solving the Problems As a result of intensive study based on the above facts, the inventors have found that the liquefied slurry is lightly centrifuged on the inlet side of the distillation column and then distilled to remove the ash content of the residue from the bottom of the distillation column. It is now possible to control the content to 20 to 35% by weight, and by adding water produced in the liquefaction reaction process to the ash-rich component after centrifugation and centrifuging it again, solids such as ash can be reduced. It has been discovered that it is possible to recover the adhered liquefied oil.

That is, the present invention provides a two-stage solid-liquid separation method consisting of a first-stage light separation operation using a centrifuge in a solid-liquid separation step, and a second-stage separation operation using a distillation column having the ability to process the separated components. It has the following characteristics, and its gist is as follows.
The liquefied slurry, which contains a large amount of liquefied oil, is extracted from the bottom of the distillation column using a centrifuge, and the ash content of the residue is 20%.
It is characterized by separating into a component with a low ash content, which has been lightly deashed to ~35% by weight, and a component with a high ash content, and among these, the component with a low ash content is supplied to a distillation column for solid-liquid separation. After centrifugation, the components with high ash content are centrifuged again after adding water produced in the liquefaction reaction process, and then the components with low ash content after centrifugation are liquefied in a distillation column or gas-liquid separator. This is a method for liquefying coal, which is characterized by supplying the coal to a produced oil separation device and recovering the liquefied produced oil.

Function When centrifuging the liquefied slurry, the centrifugal separator was controlled so that the ash content of the residue extracted from the bottom of the distillation column was 20 to 35% by weight. If the content is less than 20% by weight, the viscosity at the operating temperature of the distillation column will be 1 poise or less, and it will not be possible to handle it with a normal residual liquid extraction pump.
As mentioned above, if it exceeds 5% by weight, the fluidity of the residue extracted from the bottom of the distillation column will be significantly reduced, and there will be no preliminary operation to mix a large amount of liquefied product oil into the liquefied residue to reduce the ash content. .

In this invention, coal liquefied slurry is separated into ash with a low ash content and ash with a high ash content through a first-stage light separation operation using a centrifuge, and the components with a low ash content are separated through a second-stage separation operation using a distillation column. Since the solid-liquid separation is carried out by the method, the fluidity of the residue extracted from the bottom of the distillation column does not decrease, and a stable and efficient separation operation becomes possible.

It is economical because the ash containing a large amount of ash produced in the first stage centrifuge is centrifuged again after adding water produced in the liquefaction reaction step, and then the liquefied oil in the component is recovered.

Embodiment FIG. 1 is a flow sheet showing an embodiment of the present invention, in which (1) is a coal slurry preparation tank, (2> is a preheater,
(3) is a liquefaction reaction tower, (4) is a high temperature gas-liquid separator, (5)
(6) is a distillation column, (7) is a solvent hydrogenation reaction column, and (8) is a low-temperature gas-liquid separator.

First, coal (10), a liquefaction promoting catalyst (11), and a liquefaction solvent (12) are supplied to a coal slurry preparation tank (1) to prepare a coal slurry. The respective weight ratios in this coal slurry are not much different from known conditions, and are preferably coal 1
10-50g of liquefaction accelerating catalyst and 1 liter of liquefaction solvent per kg
~2 kg.

Next, this coal slurry is supplied to a preheater (2) and heated, and then liquefied in a liquefaction reaction tower (3), and the liquefied reaction product is transferred to a high-temperature gas-liquid separator (4) and a low-temperature gas-liquid separator (8). Gas (Gl)
, water (Hl) and slurry (S L).

Note that the liquefaction reaction conditions are not particularly limited and may be conventionally used conditions, preferably a reaction temperature of 430-4
The temperature is 60°C, the reaction pressure is 150 to 190 kg/cm"G, and the reaction time is about 0.5 to 2.0 h.

Subsequently, the liquefied slurry (Sl) after separating gas and water using a high/low temperature gas-liquid separator is supplied to a centrifuge (5), and contains a large amount of liquefied oil and is distilled from the bottom extraction residue in a distillation column. It is separated into ash (S2) which has been lightly deashed so that the ash content is 20 to 35% by weight, and ash (S3) which contains a large amount of ash, and the ash (S2) is sent to a distillation column (6). supply to.

The ash content of this component (S2) varies depending on the separation performance of the distillation column to be supplied, but in the case of conventionally used vacuum distillation columns or steam distillation columns, the ash content is 20% by weight or less, preferably 5 to 10% by weight. That's about it.

In addition, when the ash content of component (S2) is 20% by weight or more, the ash content of the residue extracted from the bottom of the distillation column is 35% by weight.
If the ash content of the component (S2) decreases significantly, the amount of liquefied oil mixed into the component (S3) will increase significantly, increasing the secondary centrifugation load and liquefying it. This is not preferable because the amount of loss of produced oil increases.

On the other hand, the component (S3) containing a large amount of ash is extracted from the distillation column (6
) or low-temperature gas-liquid separator (8). At this time, by adding water produced in the liquefaction reaction step to component (S3), the specific gravity of the liquid phase is lowered and the separation efficiency is improved, and it is expected that the liquefied oil that dissolves in water can be recovered.

In the distillation column (6>), these are separated into solid and liquid to produce liquefied oil (
S) and liquefaction residue (S') with an ash content of 20-35% by weight
A part of the produced oil (S) is supplied to the solvent hydrogenation reaction tower (7).

Next, the results of a liquefaction experiment conducted under the reaction conditions shown in Table 2 using Badr River coal from Canada whose analysis values are shown in Table 1 will be described.

First, the obtained liquefied slurry was supplied to a distillation column without passing through a centrifuge, and solid-liquid separation was performed only in the distillation column.

At this time, the heat load on the distillation column was gradually increased until it became impossible to extract the residue from the bottom, and the residue was periodically sampled, and the viscosity at the operating temperature of the distillation column was measured. The results are shown in FIG.

From Figure 2, as the heat load on the distillation column increases and the ash content of the bottom extraction residue increases, the viscosity increases.When the ash content exceeds 35% by weight, it exceeds the capacity of the bottom extraction pump, and when it reaches 40% by weight, the viscosity increases. It is recognized that it becomes impossible to extract.

Next, the liquefied slurry is fed to a centrifuge and subjected to mild centrifugation, and then the component with a low ash content (s2) is fed into a distillation column, and the component with a high ash content (s3) is the water produced in the liquefaction reaction process. was added and centrifuged again, and this component with a low ash content was supplied to a distillation column to carry out a two-stage solid-liquid separation method.

At this time, by changing the centrifugation time of the liquefied slurry,
Components with different ash contents were prepared and supplied to the distillation column, and the relationship between the ash content of the residue extracted from the bottom of the distillation column at that time and the amount of component (s3) produced after centrifugation was investigated. As shown in the figure.

From Figure 3, as the natural content of component (S2>) increases, the ash content of the residue extracted from the bottom of the distillation column decreases;
It is observed that the amount of component (33) that requires secondary centrifugation increases, and that a large amount of liquefied product oil is mixed into this.

In addition, when solid-liquid separation is performed only in a distillation column, when only the component (S2) after the first centrifugation in a two-stage solid-liquid separation method that includes a centrifugal separator is supplied to the distillation column, and when the The separated component (S3) is subjected to secondary centrifugation to obtain the component (S3).
Table 3 shows a comparison of the liquefied product yield when 2> is also supplied to the distillation column, and Table 4 shows the analysis results of the residue extracted from the distillation column.

From Tables 3 and 4, when solid-liquid separation is performed only in the distillation column, the liquefied oil yield is at most 34% per anhydrous coal.
．． However, at this time, the ash content of the residue extracted from the bottom of the distillation column reached 43.1% by weight, and soon it became impossible to extract it from the bottom of the distillation column.

On the other hand, when implementing a two-stage solid-liquid separation method that includes a centrifugal separator, if only the first centrifugal separation fraction (S2) is supplied to the distillation column, the liquefied oil yield is 31.6 wt. %, which was slightly lower than when solid-liquid separation was performed using only the distillation column, but it was possible to continuously and stably extract the residue from the bottom of the distillation column.

Furthermore, when the second centrifugal fraction (S3) is also supplied to the distillation column, the yield of liquefied oil reaches 44.4% by weight, and the ash content of the residue extracted from the bottom of the distillation column at this time is 3.
0. Good fluidity was shown in terms of OfE amount %.

From the above results, the effectiveness of the two-stage solid-liquid separation method according to the present invention was confirmed.

Table (it%, dry) Table (weight%) As explained in detail, this invention involves a light separation operation in the first stage using a centrifuge, and a distillation column having the ability to process the separated components. The two-stage solid-liquid separation method consisting of the second-stage separation operation enables stable and efficient separation operations that correspond to the properties of the liquefied residue. This is an extremely excellent invention that provides the necessary technically and economically suitable liquefaction process.

[Brief explanation of drawings]

FIG. 1 is a flow sheet showing an apparatus according to an embodiment of the present invention.
Figure 2 is a diagram showing the relationship between viscosity and ash content at the distillation column operating temperature in an example of this invention, and Figure 3 is the same.
FIG. 3 is a diagram showing the relationship between the ash content of the residue extracted from the distillation column and the amount of solid components produced after centrifugation in Examples. 1... Coal slurry preparation tank 3... Liquefaction reaction tower 5... Centrifugal separator 7 - Solvent hydrogenation reaction tower 2... Preheater 4... High temperature gas-liquid separator 6... Distillation column No. Figure 2 Figure 3 Ash content (wtP) of the residue extracted from the distillation column Voluntary procedure amendment 1゜Indication of the case Flat bottom 1 year Patent Application No. 321958 2゜Name of the invention Coal liquefaction method 3゜Person making the amendment 4゜Agent 5゜Subject of amendment 1, Mei N5, page 12, line 11, r43.1% by weight'', line 17, r31.6% by weight''
and r31.9% by weight, respectively. 2.Page 15, line 15 of the same specification “Solid components after centrifugation”
is corrected to "of the component containing a large amount of ash after the first centrifugation."that's all

Claims (1)

[Scope of Claims] 1. In the solid-liquid separation step of a coal liquefaction process, when a liquefied slurry is separated into a liquefied oil with a boiling point of up to 538°C and a liquefied residue in a distillation column, the ash content of the residue extracted from the bottom of the distillation column A method for liquefying coal, which comprises centrifuging a liquefied slurry in advance so that the liquefied slurry has a ratio of 20 to 35% by weight, and then supplying a component with a low ash content to a distillation column. 2. Water produced in the liquefaction reaction step is added to the ash-rich component of the liquefied slurry after centrifugation, and the liquefied slurry is centrifuged again, and the ash-rich component after centrifugation is recycled to the liquefaction process. The method of liquefying coal according to claim 1.