JPS58180586A - Liquefying coal-oil slurry by hydrogenation - Google Patents

Abstract

PURPOSE:To prevent carbonization of a coal-oil slurry in a preheating process, by effecting preheating of the coal-oil slurry to the hydrocracking temperature in the presence of a radical stabilizer, followed by liquefaction by hydrogenation. CONSTITUTION:In the production of liquefied coal oil by hydrogenation liquefaction of a slurry of slack coal in oil, the slurry is preheated to the hydrocracking temperature in the presence of a radical stabilizer selected from among the compds. of formulas I (where R is 1-15C alkyl or phenyl with 1-15C alkyl in side chain; M is metal such as Ni and Zn), II (where R1-2 are each 1-8C alkyl), III, IV (where R is 1-8C alkyl) and V. The stabilizer R is fed into a mixing tank 1 in the form of liquid or powder and is blended with slack coal C and medium B. The mixture is led into a preheater 2 and then a reaction vessel 3.

Description

Detailed Description of the Invention In the hydrogenation and liquefaction of coal, the present invention prevents carbonization of the coal-oil slurry during the preheating process by preheating the coal-oil slurry at a hydrocracking temperature of 1 in the presence of a radical stabilizer. It relates to a method for preventing hydrogenation and then liquefying the hydrogenation.

Conventionally, in direct coal liquefaction methods, such as direct water removal method, solvent extraction method, and bifurcation method, raw material coal is crushed into powder and mixed with appropriate medium oil to form powder oil slurry. , this slurry is heated to a reaction temperature of, for example, 380~
It was heated to 500°C and reacted with hydrogen under high pressure.

However, all coal liquefaction methods involve a step of raising the temperature of the coal-tower slurry to the reaction temperature, that is, a preheating step, which has the disadvantage that corking and carbonization occur during this step, which hinders long-term continuous operation. If carbonization occurs during the preheating process, carbon will precipitate on the heat transfer surface of the preheater, impairing heat transfer, and may lead to accidents such as clogging of pipes and damage due to overheating of the pipe wall temperature.

For this reason, conventional coal liquefaction plants have taken measures such as (a) reducing heat flux, (b) avoiding direct heating, and (c) introducing hydrogen sludge in front of the preheater. However, even with these measures, the drawbacks mentioned in -F could not be avoided.

In other words, (a) requires a significantly larger preheater, and (b) requires a separate combustion chamber and heating section, which inevitably makes the device more complicated and larger. In c), the temperature in the preheating process is lower than that in the reactor;
Therefore, since the reactivity of hydrogen is not large, we cannot expect much carbonization prevention effect, and the volume occupied by the slurry decreases by the amount of hydrogen introduced, and as a result, the time the slurry remains in the preheater becomes shorter. In terms of preheater performance, this is a minus.

Therefore, the present invention aims to eliminate the above-mentioned drawback, that is, the carbonization in the preheating process of direct liquefaction of coal.Compared to the conventional method, the heat flux can be made much higher, and there is less carbonization in the preheating process. It has the advantage of being able to operate safely for long periods of time without the risk of pipe blockage or damage, and that it can also be heated over a direct flame.

That is, the method for hydrogenating and liquefying coal-oil slurry of the present invention is as follows:
When producing coal liquefied oil by hydrocracking powdered coal in the form of an oil slurry, the oil slurry of the powdered coal is converted into the following general formula (I
), a monosulfide represented by the following general formula (11), a monoselenide represented by the following general formula (kawa), a monoselenide represented by the following general formula (
fV), an aromatic secondary or tertiary amine, a phosphoric acid ester represented by the following general formula (V), and a di-tert-butyl-optional phenolic antioxidant. The method is characterized in that it is preheated to a VC hydrogenolysis temperature in the presence of at least one compound selected from the group consisting of: and then hydrogenated.

RI S R2 (II), RI Se
R2 (11) ((RO)2PS2)2M
(IV) (RO)3 PO (V) Takashiku I) In the formula, R is an argyl group having 1 to 15 carbon atoms,
or represents a phenyl group that associates with an alkyl side chain having 1 to 15 carbon atoms, M is Ni, Zn + Mo + Pb
, Cd, Sn, W and Fe, in the formula (II), R1 and R2 are each equal or different alkyl groups having 1 to 8 carbon atoms, In the formula (Ill), R1 and R2 are the same alkyl groups as in the above formula (II), and in the formula (IV), R is an alkyl group having 1 to 8 carbon atoms, and M is the same as in the above formula (I). In the formula (V), R represents the above-mentioned (IV
) is an alkyl group similar to the formula.

The carbonization prevention method of the present invention involves adding a specific additive, that is, a carbon stabilizer, to the raw material powder coal-oil slurry in order to prevent carbonization from occurring during the preheating process of the direct coal liquefaction method. There are certain characteristics. The additive used in the present invention is at least one compound selected from the group consisting of (1) to (7) below.

(1) N,N-disubstituted/thiocarbamine salt represented by the following general formula (I).

Here, in the formula (I), R is an alkyl group having 1 to 15 carbon atoms,
Kashida represents a phenyl group having an alkyl side chain having 1 to 15 carbon atoms, and M is Ni + Zn, Mo.

There are 21 metal pieces selected from the group consisting of Pb, Cd, Sn, W and Fe.

(2) Monosulfite represented by the general formula (n).

R, -8-R2 (II) In the formula (II), R1 and R2 are each the same or different alkyl groups having 1 to 8 carbon atoms.

(3) A monoselenide represented by the following general formula (III).

R+ Se R2(m) (TTI) In the formula, R3 and R2 are the same or different alkyl groups having 1 to 8 carbon atoms, respectively, as in the above formula (II).

(4) A dialkyl/thiophosphate metal salt represented by the following general formula (IV).

((RO)2PS2 '12 M (IV) In the above formula (IV), R is an alkyl group having 1 to 8 carbon atoms, and M is Ni or Zn as in the above formula (I).

Mo, Pb, Cd, Sn, W and F
It is a divalent metal selected from the group consisting of e.

(5) Aromatic secondary or tertiary amine.

Tatoeha, diphenylamine, triphenylamine, phenylnaphthylamine, diphenylphenylenediamine, dinaphthylphenylenediamine/etc.

(6) A phosphoric acid ester represented by the following general formula (V).

(RO)3PO(V) In formula (V), R has 1 to 1 carbon atoms, as in formula (IV) above.
8 alkyl group.

(7) Di-tert-butyl substituted phenolic antioxidant.

For example, 2,6-tert-butyl-p-FureH
3 4,4'-methylenebis(2,6-tert-butylphenol).

tert C4 tert C4 4,4'-thiobis(6-tert-butyl-Q-cresol).

H3CH3 4,4'-bis(2,6-tert-butylphenol) tertC4tertC4 and the like belong to this phenolic antioxidant.

The compounds shown in (1) to (7) above have the function of stabilizing free radicals generated in the process of hydrogenolysis and liquefaction of coal, as described below. At least one compound selected from the group consisting of 11 to (7) is added to the pulverized coal-oil slurry as a radical stabilizer.

When such a radical stabilizer is added to a powdered coal-oil slurry, the reaction is carried out, for example, as follows.

FIG. 1 is a process diagram showing a generally employed direct hydrogenation and liquefaction process for coal. It is mixed with C and medium oil B, and is sent together with hydrogen to the preheater 2 to be preheated in a state contained in -pulverized coal-oil slurry-, and then supplied to the reactor 6.

Here, the amount of the radical stabilizer added to the powdered coal-oil slurry is usually about 10-5 to 10-1 mol per kg of anhydrous ash-free coal of raw material coal.

If the amount of radical stabilizer added is less than 10-5 mol, it will not be possible to sufficiently stabilize the radicals generated from coal during the coal preheating process, and if the amount added exceeds 10-1 mol, the radicals will no longer be stabilized. Its function as a stabilizer reaches a saturated state, and even if it is added more than 1, no difference in effectiveness will be observed.

The coal used in the present invention is usually used in the form of fine powder coal smaller than about 60 mesh, preferably less than about 100 mesh, and the medium oil for slurry formation is an aromatic oil obtained by coal liquefaction, such as Although oil is generally used, it is not limited thereto. 'Also, the coal concentration in the slurry can be selected as appropriate; for example, a coal concentration of 20 to 50% by weight is generally employed.

As mentioned above, the pulverized coal-oil slurry to which the fuel/cal stabilizer has been added is preheated because the raw coal usually undergoes thermal decomposition and hydrocracking reactions at 380 to 500°C, preferably 400 to 480°C. 380-500° from room temperature in container 2
The temperature is raised to C. The pressure during this preheating process is
It is determined by the pressure required for the next coal liquefaction reaction, and usually 50 to 500 atmospheres from normal pressure is adopted. The coal-coal slurry supplied to the reactor 6 was heated at 380 to 500'C, 50
It is maintained at ~500 atmospheres and hydrogenated and liquefied. The reaction product is sent to a gas-liquid separator 4 for gas-liquid separation, and then the gas component is washed by a gas washer 5 and used as a pipe incas 6 or LPG 7. The hydrogen residue is still sent to the preheater 2 via the pipeline 8 and subjected to reaction.

The liquid valve from the gas-liquid separator 4 is fractionated in a fractionator 9 to become light oil 10, which is then distilled in a vacuum distiller 11 and then taken out as fuel oil 12. Residual oil goes to pipeline 16
The hydrogen is sent to the gasification furnace 14, where it is gasified in the presence of water vapor 15° and oxygen 16, and is supplied to the preheater 2 as hydrogen 18 through the conversion refiner 17. Further, the liquid valve 19 from the gas-liquid separator 4 is supplied as medium oil B to the mixing tank 1.

The type of coal used in the present invention can be arbitrarily selected and is not limited to bituminous coal, but includes subbituminous coal, brown coal,
A wide variety of coals, such as lignite, can be used, each with significant effects as described below.

Next, the present invention will be discussed from the viewpoint of the reaction mechanism. Usually, the reaction of hydrogenating coal to obtain a liquid product is considered to be a radical reaction. That is, the thermal decomposition of coal produces only free radicals. The free runcal is stabilized by combination with molecular hydrogen or hydrogen supplied from the slurry media oil to produce a liquid product. However, since thermal decomposition of coal already starts around 300°C, free runcal generated by thermal decomposition of coal already exists in the preheater. If these free radicals are not stabilized by molecular hydrogen or hydrogen from the slurry medium, they will undergo polycondensation reactions and progress to carbonization reactions. However, since there is a temperature region in the preheater during heating that is not as high as in the reactor, molecular hydrogen or hydrogen from the slurry medium is usually not activated enough to contribute to the reaction, and therefore free radicals are stable. It is not enough to become a standard. However, even in a relatively low-temperature region where the 1,1-radical stabilization mechanism (by molecular hydrogen or hydrogen supplied from medium oil) cannot be expected,
When a radical stabilizer is present as in the present invention, free radicals are quickly stabilized and carbonization is prevented from occurring within the preheater.

1- According to the present invention as described above, the following excellent effects can be achieved by preheating the pulverized coal-oil slurry from room temperature to the hydrogenation and liquefaction reaction temperature in the presence of a fuel/cal stabilizer.

(a) Powdered coal-oil slurry During the preheating process, free radicals generated by the thermal decomposition of coal are stabilized by the gas/cal stabilizer. It suppresses the carbonization of free radicals caused by polycondensation reactions, prevents coking and carbonization caused by coke on the walls and pipes of the reactor, and allows safe continuous operation over long periods of time.

(b) As a result of preventing carbonization on the inner wall of the preheater, a decrease in the heat retention coefficient is prevented, and there is almost no pressure drop in the preheater. Accidents such as damage and breakage are prevented.

(c) The heat flux in the preheater is usually 5,000 to 10,000 Btu/ft2/h for the purpose of reducing carbonization.
However, according to the present invention, the heat flux is s, o
Expanded to oo ~ 30,000 Btu/ft2/hr. It is possible to make the slave-to-C pre-M device compact.

In addition, since carbonization is prevented, the preheater can be of the ILi fire heating type. Therefore, there is no need to separate the heating section from the combustion chamber of the preheater, and it is possible to avoid complication and enlargement of the device.

Since the amount of radical stabilizer used in the present invention may be extremely small, it does not change the slurry properties of the pulverized coal-oil slurry, and it can be applied to existing coal liquefaction plant equipment with almost no changes. Moreover, since the radical stabilizer can be easily obtained or synthesized, the cost of the liquefied product does not increase.

(f) By using a radical stabilizer, there is no need to introduce hydrogen into the preheater to prevent carbonization, and the volume of the preheater can be reduced by the volume occupied by hydrogen.

(g) The radical stabilizer only stabilizes free radicals generated by thermal decomposition of icocoal during the preheating process, and has no adverse effect on the hydrogen liquefaction reaction.

Examples of the present invention will be described below.

Examples 1 to 10 Pacific coal C (subbitten charcoal), which had been crushed in advance to 100 methane or less, and anthracene oil B were mixed in a mixing tank 1 to prepare a slurry having a coal concentration of 30% by weight. Next, various carcin/cal stabilizers R are added to this powdered coal-oil slurry (coal IK2 (anhydrous,
8.4 x 10-' mol added to ash-free coal
The slurry was mixed and passed through a preheater 2 as shown in FIG. 2 at a predetermined feed rate. This preheater 2 has an outer diameter of 5 mm.
, inner diameter 3 mm, length 20? ? + SUS 316
A flexible tube 2A manufactured by Amadeus Co., Ltd. was immersed in a melt bath 2B heated to 400°C by a heater 2C, and the pressure loss △P between input port PI and exit port P2 was measured at the start of slurry supply, 50 hours later, and 100 hours later. The degree of charring in the pipe was evaluated. The results are shown in Table 1 below.

The coal:media oil mixing ratio is 4:6, the slurry flow rate is 0.5009/hr, and the slurry population temperature is 60
The pressure inside the C1 spiral tube was 300 to 9/-G. Also,
In the table, Example 1 became inoperable 40 hours after the slurry was supplied, and Example 2 became inoperable 80 hours after the slurry was supplied.

As is clear from Table 1, the compounds used in the present invention have a remarkable anti-IL effect on carbonization, and this effect is greater than that of hydrogen addition in the conventional preheating process.

Note that similar results were obtained when the radical stabilizers used in Examples 1 to 10 were used in combination.

(Margins below this page) Examples 11 to 20 Under the same conditions as Examples 1 to 10, the degree of carbonization during the preheating process was examined when the compound of formula (I) was used as a radical stabilizer.

The results are shown in Table 2 below. From this Table 2, N.

It can be seen that N-disubstituted dithiocarno-mic acid metal salts are effective as radical stabilizers.

Examples 21 to 45 Under the same conditions as Examples 1 to 10, compounds used in formulas (II), (■), and (■), aromatic secondary or tertiary amines, and (V ) compounds of the formula and ter
The radical stabilizing effect of each t-butyl-substituted phenolic antioxidant was investigated. The results are shown in Table 3 below. The results in Table 3 also show that each of the above-mentioned compounds is effective as a radical stabilizer.

Example 46 In Example 3, (R=tert-)゛chill, M
= Zn), and the added amount was changed, and the pressure loss ΔP (mmAq) after 100 hours of slurry supply was measured. The results are shown in Figure 3. It is clear from FIG. 3 that almost no pressure loss is observed when the amount of radical stabilizer added is in the range of approximately 10-5 to 101 mol per 1 K9 of coal equivalent to anhydrous ash-free coal.

[Brief explanation of the drawing]

Fig. 1 is a process diagram showing an example of the present invention, Fig. 2 is a schematic diagram of a preheating device for pulverized coal-oil slurry used for evaluation of the present invention,
FIG. 3 is a diagram showing the relationship between the amount of N,N-di-tert-bunaldithioruhamic acid zinc added and the pressure loss of the preheater. 1... Mixing tank, 2... Preheater, 6... Reactor. Agent: Patent Attorney Makoto Ogawa − Patent Attorney: Ken Noguchi Patent Attorney: Kazuhiko Saishita

Claims (1)

[Scope of Claims] When producing coal liquefied oil by hydrocracking powdered coal in the form of an oil slurry, the oil slurry of the powdered coal is prepared by the following general formula (I
), a monosulfide represented by the following general formula (II), a monoselenide represented by the following general formula (III), and a monoselenide represented by the following general formula (■). selected from the group consisting of alkyl dithiophosphate metal salts, aromatic secondary or tertiary amines, phosphoric acid esters represented by the following general formula (V), and di-tert-butyl-containing noenol antioxidants. preheating to hydrogenation station temperature in the presence of at least one compound;
A method for hydrogenating and liquefying a coal-oil slurry, which comprises then hydrogenating the slurry. RR R,-8-R2(n), R,-8e-R2(lu
ll)L (RO)2PS2)2M
(IV) (RO+3PO(V) Tataku I) In the formula, R is an alkyl group having 1 to 15 carbon atoms,
Or alkyl il having 1 to 15 carbon atoms! Represents a phenyl group having an I chain, M is Ni + Zn, Mo. A divalent gold fly selected from the group consisting of Pb, Cd, Sn, W and Fe, in the formula (■), R1 and R2 are each equal or different, with carbon numbers 1 to 8
In the formula (■), R1 and R2 are the same alkyl groups as in the formula (n), and in the formula (IV),
R is an alkyl group having 1 to 8 carbon atoms, M is a divalent metal similar to the above formula (I), and in the formula (V), R is the above (IV)
It is an alkyl group similar to the formula.