JPS6236490A - Method of controlling coal liquefying reaction - Google Patents

Abstract

PURPOSE:To continuously liquefy coal in a high oil yield without occurrence of device troubles, by liquefying coal while controlling each operating factor so as to give a constant C of the given equation in a particular range. CONSTITUTION:1pt.wt. coal and 0.1pt.wt. or less catalyst such as iron powder are added to 1-2pts.wt. hydrogenated circulating solvent comprising a coal liquefied oil to prepare a slurry. The slurry is pressure fed together with hydrogen into a high temp. and high-pressure liquefying reactor. A liquefying reaction is conducted by concurrently ascending the slurry and gas, while the feed, G, of the hydrogen contg. gas is controlled so that the constant C in the equation [wherein G is the feed of the hydrogen contg. gas (Nl/hr); S is the feed of the slurry (l/hr); C is a constant; Po is the operating pressure (atm); Tb is the operating temp. (K); BP is the boiling point of the slurried solvent; alpha is the fraction of the weight of the solvent in the slurry] is in the range of 0.5-1.0. After completion of the reaction, the slurry is distilled to separate it into a light product oil, a circulating oil and a residue. The circulating oil is hydrogenated and the product is used as the hydrogenated circulating solvent for slurry.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a continuous coal liquefaction method, and the present invention relates to a continuous coal liquefaction method, and the present invention relates to a continuous coal liquefaction method, and the present invention relates to a continuous coal liquefaction method, and the present invention relates to a continuous coal liquefaction method. The present invention provides a control method.

(Prior art and its problems) Coal liquefaction is a technology that converts solid coal into liquid substances such as light oil and heavy oil. The method used is to add hydrogen to coal under high pressure and liquefy it. At that time, the rate at which solid coal is converted to liquid oil at room temperature is relatively slow, so generally 1
Reaction time is required before and after the reaction time, and in order to promote this reaction, a catalyst is allowed to coexist in the reaction atmosphere in order to obtain high quality liquefied oil. Furthermore, since it is difficult to continuously pump a solid powder such as coal into a high-pressure system, raw coal is pulverized in advance, mixed with a liquid solvent, and pumped in the form of a quasi-liquid slurry. . Therefore, in order to carry out the liquefaction reaction, a solvent is also required for this slurry formation, and many factors exist as so-called operating conditions.

In order to optimize a reaction that has such a large number of operating factors, it is necessary to repeat a huge number of experiments for each factor, but it is necessary to repeat a huge number of experiments for each factor. Considerable additional time and effort are required to perform difficult reactions. Therefore, in conventional studies of this type, although fairly detailed studies have been conducted on specific factors alone, there are almost no examples of comprehensively understanding and organizing these factors.

Operational factors in coal liquefaction reaction, namely raw coal, solvent,
The catalyst, gas flow rate, slurry flow rate, temperature, pressure, reaction time, etc. are considered as follows, assuming a continuous device. First, in a continuous device, it is very difficult to vary each factor over a wide range. In particular, considering that the volume of the reactor, 1 tW, etc., remains unchanged, it is hardly expected to change the slurry] Mi, that is, the average residence time of the slurry on an empty column basis. Furthermore, with regard to raw coal and catalysts, it is considered impossible to unify their types or amounts in the middle of the process. Therefore, there are four operational factors that can be varied to a certain extent in a continuous device: temperature, pressure, gas flow rate, and solvent. Therefore, in a continuous device, these four factors are appropriately controlled to continue stable operation.

Stable continuation of operation primarily means qualitatively and quantitatively stable production of liquefied oil from coal, and stable operation of the equipment is an essential condition for this purpose. This is because, in the gas-liquid-solid three-phase coal liquefaction reaction, serious problems such as solid sedimentation or coking that make it impossible to continue operation are likely to occur.
Therefore, in order to aim for stable production of coal liquefied oil,
In particular, it is necessary to establish methods to prevent and control problems such as blockages in advance, and to select operating conditions that will produce liquefied oil at a high yield. Therefore.

The present inventors conducted various studies regarding the above operating conditions and completed the following invention.

(Structure of the Invention) The present invention prepares a slurry by mixing coal, a solvent, and a catalyst, introduces the slurry together with a hydrogen-containing gas into a high-temperature, high-pressure reaction zone to liquefy the coal, and converts the slurry into a product after the reaction. oil,
In the coal liquefaction method, the circulating oil is separated into circulating oil and residue, and the circulating oil is then subjected to hydrogenation treatment and then circulated to the slurry preparation castle as a slurry forming solvent.
It is characterized by controlling each operating factor of the coal liquefaction reaction, or especially the gas supply amount, so that

×(exp [3,1□8 x lo= B P +3
．． 44ol)"""""""where G: Hydrogen-containing gas supply amount [N sentences/hr]] S slurry supply amount [1/hr] C: Constant PO: Operating pressure [atml Tb: Operating temperature [@K ] BP Nislurry Forming Solvent Average Boiling Point [°K]α Solvent Weight Fraction in Nisslurry (Embodiments and Functions) In the present invention, first, a hydrogenation circulation solvent consisting of coal liquefied oil, coal and a catalyst are mixed to form a slurry. Prepare. At this time, the mixing ratio of coal and solvent is 1:1 to 1:2 by weight.
As for the catalyst, for example, an iron-based powder catalyst is used in an amount of about 10 wt % or less based on the coal. It is preferable to prepare a slurry with such a mixing ratio by thoroughly stirring and mixing it in advance. This is because each component in the slurry has a different specific gravity depending on the wood quality, so when it is left still, This is because phase separation between solid and liquid occurs, making it difficult to convey to the next step.

The slurry thus prepared is then subjected to a high-temperature, high-pressure reaction step, ie, is pumped together with a hydrogen-containing gas to a reaction tower and subjected to a liquefaction reaction. Generally, as this liquefaction reactor, an open column reactor with a column height/column diameter ratio of around 20 is adopted,
The slurry and gas pass through it in co-current upward flow. Therefore, when a coal liquefaction reaction is carried out in such a reaction tower, the following inconveniences and troubles generally tend to occur. ■ Inability to overflow solids (dry-up) due to evaporation of liquids, mainly solvent, ■ Sedimentation of solid particles and bottom sedimentation due to poor mixing conditions in the reaction tower, ■ Increased gas holdup. Reduction in the reaction volume of the slurry phase due to (1) one run of reaction temperature, kneeking.

Although the phenomenon of such troubles has been recognized for a long time, unfortunately, very little research has been done on methods to reliably prevent them. ■ Only an example of overcoming the solid sedimentation from the viewpoint of slurry flow rate control is disclosed, and the other troubles mentioned above can be avoided.
Furthermore, in actual continuous equipment, which is even more important, no knowledge or insight has been obtained regarding control methods that have good responsiveness even during operation.

Therefore, the present inventors conducted intensive research on a control method to avoid these problems, and finally found the form of equation (1), more specifically, the constant C in equation (1) is 0.5 to 1. It has been confirmed that by controlling operational factors, particularly the gas supply amount, so that the above-mentioned troubles are within the range of 0, it is possible to achieve a good liquefied oil yield without causing the above-mentioned troubles.

That is, S and α in Equation 1 are the amount of slurry supplied and the weight fraction of solvent in the slurry, respectively, and these generally take almost fixed values as long as the size of the reaction column remains unchanged. Therefore, the manipulated variables are G, Po, Tb, and BP, but among these, first of all, regarding the average boiling point (BP) of the slurry forming solvent, it is practically impossible to arbitrarily change this value. This is almost impossible because the solvent is a constant fraction of the distillate after the liquefaction reaction and is used cyclically, and furthermore, the range of this fraction is almost inevitably determined. Because it belongs to Generally, the slurry after the reaction is separated into various fractions such as light oil, medium oil, and heavy oil by separation means such as distillation. From this, relatively light liquefied oils such as light oil and medium oil are extracted as product oil, and the remaining medium oil and heavy oil are recycled and used as a slurry solvent. Become. Therefore, as long as the circulating solvent is produced in this way, there is little freedom to change its properties, and only a small amount of processing is allowed in the next hydrotreating process. For this reason, first of all, it is difficult to arbitrarily change BP, but secondly, operating pressure (Po) and operating temperature (Tb) can be arbitrarily changed in principle.

However, these methods are extremely inefficient when considered from the viewpoint of so-called response or control time.

This is because, as is well known to those skilled in the art, changing the pressure rapidly can cause trouble, so very careful operation is required when changing the pressure. On the other hand, regarding temperature changes,
Even if this was attempted to be done by manipulating the heat source, the sensitivity would be extremely low. This is because high-temperature, high-pressure liquefaction equipment is a container,
Because all piping and other equipment is made of thick-walled pressure-resistant materials, and in most cases heat is supplied using an external heating method, even if an external heat source is operated, it takes a long time before the change is transmitted to the internal fluid. This will result in a considerable response delay. Therefore, although these values can be arbitrarily determined as initial settings, it is not very desirable to change these values during operation.On the other hand, when the hydrogen-containing gas supply ff
Regarding i (G), in actual equipment, the flow rate is controlled by a flow rate control or pressure control valve.

Therefore, regarding G, it is possible to arbitrarily change the flow rate by changing the valve opening, and furthermore, with a general air-driven type, the setting change can be completed in almost seconds. is possible.

Therefore, when controlling the liquefaction reaction using the formula (1), it can be said that the most preferable form is to establish the formula (1) by appropriately controlling G. However, it is not possible to change G indefinitely, and a value such that C in formula (1) is 0.5 to 1.0 is preferable, and as long as it is operated within this range. This makes it possible to avoid the troubles within the reaction tower described above.

That is, under conditions where C is smaller than this range, solid particles tend to settle and the yield of liquefied oil decreases, which is undesirable. This increases the risk of increased hold-up and even dry-up, which should be avoided from the viewpoint of stable rotation of the device. Furthermore, although the liquefied oil yield improves markedly as G increases up to approximately C=1, the effect diminishes thereafter and is not economically preferable. still,
Equation (1) was derived from ideal gas theory and detailed experimental research regarding this, and the process will be explained as follows.

Now, in an ideal gas, the following equation holds.

Therefore, if we greatly simplify the inside of the liquefaction reactor and consider that it consists only of the supply gas and the slurrying solvent, and further assume that these obey the ideal gas law, the following equation holds true.

Here, PH and Pv indicate the partial pressures of the supply gas and solvent vapor, respectively, and V)4. V indicates each volume. On the other hand, if the total pressure is Po, the left side of equation (3) is expressed as equation (4).

On the other hand, regarding the right side of equation (3), it should be possible to convert it into the flow rate ratio of gas and solvent vapor, and if we also consider the case where the entire amount of solvent becomes vapor, equation (5) is obtained. However, the specific gravity of the solvent is 1, and the average molecular weight is M
Let it be τ.

W Here, as a result of various studies regarding pY, M, and r, the present inventors discovered a good correlation as shown in Figures 2 and 3, and from this, PT, Mv are (6) , it was found that it is expressed by equation (7).

P, =exp[(2,50x10Tb-3,33xlO
)BP+11 ・・・・−・−(6)M, = e
x p [3,118xlOB F+3.4401
- (7) Based on the above equations (4) to (7), the present inventors found equation (1), and further conducted studies by varying the value of G based on equation (1). , the value of constant C is 0.
It was confirmed that a good liquefied oil yield could be achieved in the range of 5 to 1.0 without causing any equipment trouble.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Example 1] Hydrotreated solvent with an average boiling point of 270°C (543°K) 1.
A slurry was prepared by using 1 part by weight of subbituminous coal and 0.03 part by weight of an iron-based catalyst to 5 parts by weight, and a coal liquefaction experiment was conducted in a continuous coal liquefaction apparatus. The experimental conditions were a reaction temperature of 450°C (723@K) and a pressure of 150°C.
ATM, average residence time 60 minutes, slurry supply amount 5 sentences/
hr, and the amount of hydrogen gas supplied was varied.

The slurry after the reaction was separated by distillation into distillate oil with a boiling point of 540°C or less and a residue, and from this the yield of liquefied oil with a boiling point of 540°C or less was calculated.
4°K) using a hydrotreated solvent at a pressure of 190 at.
A liquefaction experiment was carried out under the same conditions as above except that
The liquefied oil yield was calculated. These results are shown in Figure 1. In Figure 0, A is the result under a pressure of 150 atm and B is the result under a pressure of 190 atm, but both are under the hydrogen gas supply amount where C is in the range of 0.5 to 1-0. It can be seen that this shows a good liquefied oil yield. On the other hand, it can be seen that in the range where C is 1 or more, the liquefied oil yield hardly improves and the effect of increasing the gas amount is hardly recognized.

[Example 2] Using a hydrogenated solvent with a homogeneous temperature of 270°C, the pressure was 150a.
The same liquefaction experiment as in Example 1 was carried out by adjusting the amount of hydrogen gas supplied so that C was 0, 2, and 0.8 at tm.

First, continuous operation was carried out for 72 hours under the condition of C=0.8, but almost no change in pressure over time before and after the reaction tower was observed. On the other hand, as a result of continuous operation under the condition of C = 0.2, the pressure at the inlet of the reaction tower increased after about 25 hours, and as a result of continued operation, a rapid increase in pressure occurred after about 31 hours. occurred, and when the pressure reached 240 atm, the device interlock was activated and the device was stopped. After cooling, one reaction tower was opened and the inside was inspected, and solid matter was deposited at the bottom of the first reaction tower, blocking the inlet.

From this result, 2. C is within the range of 0.5 to 1.0.
If =0.8, continuous operation is possible, but if it is outside this range, 0 or 2, trouble will occur and continuous operation will not be possible.

(Effects of the Invention) According to the present invention, continuous coal liquefaction operation with a high oil yield is possible without causing equipment trouble.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the value of C and the liquefied oil yield in Example 1, Figures 2 and 3 are graphs showing the relationship between BP and py (solvent partial pressure of steam)
and is a graph showing the correlation between BP and M-pr (average molecular weight of solvent).

Claims (2)

[Claims] (1) Prepare a slurry by mixing coal, a solvent, and a catalyst, introduce the slurry together with a hydrogen-containing gas into a high-temperature, high-pressure reaction zone to liquefy the coal, and after the reaction, the slurry is used as product oil, circulating oil, and residue. In the coal liquefaction method, the circulating oil is then hydrotreated and then circulated to the slurry preparation area as a slurry solvent.
1. A method for controlling a coal liquefaction reaction, characterized in that each operating factor is set such that 0.5 to 1.0. G/α・S=C{P_0/exp[(2.50×10^
-＾5Tb-3.33×10＾-＾2) BP+11]-
1}X{22400/exp[3.118×10^-^
3BP+3.440]}・・・・・・・・・(1) Here, G: Hydrogen-containing gas supply amount [Nl/hr] S: Slurry supply amount [l/hr] C: Constant P_0: Operating pressure [atm ] Tb: Operating temperature [°K] BP: Average boiling point of slurry forming solvent [°K] α: Weight fraction of solvent in slurry (2) By controlling G, the value of C can be adjusted from 0.5 to 1.
A method for controlling a coal liquefaction reaction according to claim (1), wherein the coal liquefaction reaction is within a range of 0.