JPH0598269A - Prevention of blockage of slurry preheater - Google Patents

Abstract

PURPOSE:To prevent the blockage of a slurry preheater by using a pre-sulfided metal oxide as a catalyst for a coal liquefaction reaction. CONSTITUTION:A metal oxide (e.g. iron ore) as a catalyst, an oil (e.g. crystal- free anthracene oil) as a medium and a promoter (e.g. powdered sulfur) are fed to a preparation tank and subjected to pre-sulfidation. The promoter sulfur is used in an amount to give an atomic ratio to the iron atoms of the catalyst of 0.2-1. The presulfidation is performed for at least 15min at 50-500 deg.C in a hydrogen stream. After the presulfidation, powdered coal and powdered sulfur are mixed into the mixture to form a slurry. The coal (Pacific coal which can pass a 100-mesh screen) is used in a concentration of 30-50% and the catalyst is used in an amount to give an Fe/DAF coal weight ratio of 0.02-0.03 in the presulfidation. The promoter sulfur in the liquefaction is used in an amount to give an S/Fe atomic ratio of 0.02-3. The liquefaction is performed for 30-90min at 420-460 deg.C under a reaction pressure of 170-200kg/cm<2> in a hydrogen stream. According to this process, the liquefier can be operated continuously for a long time without blocking the slurry preheater.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing clogging of a slurry preheater in coal liquefaction.

[0002]

2. Description of the Related Art In recent years, coal liquefaction has been advantageous because it has the advantage of directly supplying petroleum alternatives in the face of problems such as fuel oil resources, provision of chemical raw materials, diversification of chemical products, and energy diversification. Technology development is essential. Regarding this coal liquefaction, a method of pulverizing coal, heating it, and adding hydrogen as necessary to obtain a liquefied product containing a gas and a solid substance has been studied for many years, and many techniques are known.

Even today, the technological development is very active,
Many new technologies are being developed. However, there are still many problems in terms of the economical efficiency seen in the synthetic crude oil production method and the liquefaction yield, and the efficient production of high-quality fuel oil, gasoline or chemical feedstock oil. For example, it may be necessary to add expensive catalysts or catalysts that are not desirable in terms of pollution or pollution, or to form carbides during the reaction.

The coal liquefaction reaction is very complicated, and is roughly classified into thermal decomposition of coal, hydrogenation of free radicals produced,
It is divided into three steps, hydrogenolysis and hydrogenation, which involve the cleavage of aromatic rings. Therefore, in order to control these reactions well, the reaction conditions in the coal reactor, in particular the choice of the catalyst among them, is of course an important factor in determining the quality of the liquefied oil, and of course it is a selective factor in the coal liquefaction process. It can be said that the contribution of the catalyst is the largest in the complete hydrogenation and hydrocracking. For this reason, various catalysts having different chemical species and physical shapes have been developed, including addition methods.

There are a great number of conventionally known coal liquefaction catalysts, but among them, there are many typical examples of zinc chloride, tin chloride, aluminum chloride, nickel chloride, iron chloride, etc. Belong to For sulfides, tin sulfide, molybdenum sulfide, lead sulfide, copper sulfide, zinc sulfide, nickel sulfide, for oxides nickel oxide, silica, alumina, iron oxide, cobalt oxide, molybdenum oxide, titanium oxide, tungsten oxide, vanadium oxide, etc. There are also known uses of mixtures thereof, red mud, iron ore and the like.

The above catalysts can be roughly divided into three systems. The first system is a halide system, especially a chloride system, which exhibits an excellent catalytic effect for coal liquefaction. Among them, the molten salt method, which is used at high concentration, is rich in the production of light oil, produces a small amount of gas, and can obtain a high coal liquefaction rate, but of course there are major restrictions on the equipment materials, and coexisting hydrogen chloride gas. There is a problem such as corrosion due to. The second system is a petroleum-based catalyst, which is effective for hydrogenating heavy oils, as is mainly found in oxides or sulfides of transition metals such as Co, Mo, Ni, W, etc. Since it is easily received and used under severe conditions, there is a drawback that the catalyst activity is significantly reduced and the catalyst life is short.

Since these catalysts are generally expensive, H-
Coal process, secondary hydrogenation, devised to remove deteriorated catalyst in the reactor like the boiling bed found in upgrading, regeneration, supply system, or using the catalyst at a very low concentration like Dow method, In addition, most of them are reused and recycled, and original emulsion catalysts are being developed, but there are many problems such as optimal emulsification method and selection of emulsifier. That is, none of them have reached the stage of completion. The third system is an iron-based catalyst. It is cheap and often used as a disposable catalyst. Among them, iron hydroxide, red mud, iron ore, iron oxide, iron sulfate, etc. are typical.
Usually, these catalysts are used by suspending them in a slurry composed of coal and a solvent, but deterioration due to ash deposition on the catalyst is inevitable. Therefore, in order to maintain activity, it is required to have a fine and large surface area, and a measure to improve dispersibility,
Alternatively, it is necessary to take measures such as increasing the amount used. The activity of these iron compounds increases dramatically when sulfur coexists. Therefore, it has also been proposed to add sulfur to coal for use in coal having a low sulfur content.

[0008] In particular, the use of iron ore, red mud, laterite, iron oxide, scrap iron, and the like, which are by-products after the acquisition of valuable materials, has received much attention because they are inexpensive. Conventionally, such a catalyst is
In order to improve the catalyst performance, the case of using finely pulverized was the mainstream. In this case, the problem is that the iron ore +
With S, iron oxide + S, red mud + S, and laterite + S as catalysts, the pressure loss of the slurry preheater gradually increased with the passage of operating time, and after 50 hours,
It is about 5 kg / cm ² . Further, when the operation is continued, the pressure loss becomes remarkably large, and finally the operation becomes impossible, so that the operation for a long time cannot be achieved.

In the open inspection after the completion, during the liquefaction reaction, the deposits were deposited almost uniformly on the inner wall of the vessel (inner wall of the tube) along the coil heater wound along the outer periphery of the preheater. This phenomenon was almost the same when an iron oxide catalyst was used. When the deposit was analyzed, it was thought to be the catalyst component and the ash content in the coal. From this, it is considered that the iron oxide-based catalyst on the vessel wall has a higher adhesive force at high temperature and further adheres to the vessel wall, and ash is adhered and grown using the adhered catalyst as a binder. Iron oxide catalysts have the following problems in summary. Strong adhesion. Low activity, required in large amount to maintain liquefaction performance. It adheres in the preheater, causing a large pressure loss and becoming a blockage,
It becomes impossible to operate. Continuous operation for a long time at a liquefaction plant (1000-2000
There are few results of (time). The heat transfer loss of the preheater is large. The physical properties of the liquefaction change due to local overheating of the preheater.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to enable a long-term continuous operation of a liquefaction plant.

[0011]

Means for Solving the Problems The inventors of the present invention have made extensive studies to solve these problems, and have developed an ideal liquefaction method in coal liquefaction, as will be described later. This method, as represented by iron ore, has established a treatment method that solves all of the above-mentioned problems including cost reduction, which is the greatest advantage.

[0012] After pre-sulfurizing the iron ore, etc., of the catalyst used in the medium oil in advance, coal is added to form a slurry, and the deposited matter does not adhere to the inner wall of the vessel or deposit on the bottom and goes through the preheater to the reactor. It has made it possible to provide a method of advancing and performing stable coal liquefaction for a long time here. By the way, no pressure loss was observed in the preheater after 50 hours of operation, and the differential pressure was about 2 kg / cm ² .

That is, the present invention is a method for preventing clogging of a slurry preheater in coal liquefaction, which is characterized by using a pre-sulfurized metal acid compound as a catalyst. The present invention is
By pre-sulfiding the catalyst such as iron ore to be used in the medium oil in advance, it is highly dispersed in the coal slurry and the adhesion of the catalyst is relaxed to eliminate the adhesion to the inner wall of the preheater,
Further, it is possible to prevent the ash content in the coal using the catalyst as a binder and to promote stable liquefaction.

By the way, the presulfurization referred to in the present invention will be described. Usually, the coal liquefaction reaction is 43 under H ₂ flow.
The slurry prepared by adding powdered coal to medium oil and sulfur as a catalyst and a cocatalyst in advance is fed into a reactor kept at 0 to 500 ° C. and 150 to 250 kg / cm ² , Pre-sulfurization means that a catalyst used for coal liquefaction and sulfur as a co-catalyst are added to medium oil in advance before coal chlorination, and a sulfurization reaction is performed at 200 to 400 ° C. which is lower than the temperature of coal liquefaction.

In this case, the sulfur content of the cocatalyst can be adjusted to carry out the sulfurization reaction of all or part of the added catalyst, but sulfurization of about 20 to 50% is preferable. Further, after the reaction is completed, coal can be liquefied by adding coal to form a slurry and sending it to the reactor through a preheater without separating the catalyst. Further detailed study revealed that the method of preventing scale adhesion to the preheater is not limited to presulfurization.
For example, the liquefaction reaction using iron ore mixed with a small amount of pyrite as a catalyst showed a similar effect to the case of presulfiding.

The metal oxide referred to in the present invention means oxides of iron, nickel, cobalt, molybdenum, zinc, tin, etc., iron ore, scrap iron, illuminite, laterite, ore, etc. Alternatively, it may be added on a carrier. When used, it may be one kind or a mixture of two or more kinds. And iron ore is limonite (carol), magnetite (itabira,
Any of the loblibers) may be used and is not of course specified. In order to reduce the proportional manufacturing cost of the catalyst,
Iron scrap or the like can be used as a starting material for iron. In particular, itabila and lobliber are easy to pre-sulfide. The particle size of the iron ore may be about 2 to 5 μm as a 50% average particle size, and the specific surface area is about 5 to 50 m ² / g.

In the case of pre-sulfurization, the medium oil used is preferably liquefied oil of coal or an oil obtained by hydrogenating liquefied oil, but creosote oil, anthracene oil, petroleum distillate and the like may be used alone or a mixture thereof. It may be oil. The boiling point of the medium oil is preferably about 150 to 600 ° C. The amount of catalyst and the amount of medium oil at the time of presulfiding may actually be any ratios, but it is convenient as long as the slurry concentration and the amount of catalyst that are set are set at the time of coal liquefaction.

The amount of the co-catalyst S added may be 0.2 to 1 in atomic ratio with respect to Fe of the catalyst, but 0.2 to 0.5 is sufficient without adding more than necessary. The reaction temperature for presulfiding is 5
It may be 0 to 500 ° C., preferably 200 to 400
℃ is good. If the reaction time of presulfurization is 15 minutes or more, there is no adverse effect even if it is a long time. 30-60 in most cases
Minutes are enough. Also, the sulfurization atmosphere does not necessarily have to be under H ₂ flow, but considering the liquefaction reaction after sulfurization, H _2
2 It is more convenient to use an atmosphere under circulation.

When the pre-sulfurization reaction is completed, powdery coal is added to maintain the concentration at 30 to 50%, but in many cases, 40% or less is preferable in view of fluidity. The amount of catalyst is set to 0.02 to 0.03 (weight ratio) of Fe / DAF on the basis of anhydrous ashless coal (hereinafter referred to as DAF) at the time of presulfiding. The co-catalyst S in the liquefaction reaction may have an atomic ratio of S / Fe of about 0.5 to 3, preferably 1 to 1.4, but usually about 1.2.

In order to enhance the performance in liquefaction, the temperature is usually 420 to 460 ° C., the reaction time is 30 to 90 minutes, and the reaction pressure is 170 to 200 kg / cm ² under H ₂ flow.
Better keep it at. This condition must be set appropriately according to the type of coal used. Hereinafter, the present invention will be specifically described with reference to examples.

[0021]

【Example】

[0022]

Example 1 and Comparative Example 1 Pre-sulfurization and coal liquefaction are shown in FIG.
The continuous reactor shown in 20 kg / day was used. The operating conditions are as follows. Presulfidation (1) Catalyst concentration: Iron ore (as Fe) / anthracene oil = 0.02 (weight ratio) (2) S addition amount: S / Fe = 0.5 (atomic ratio) (3) Reaction temperature: 300 ℃ (4) Reaction time: 30 minutes Coal liquefaction (1) Coal: Pacific charcoal (100 mesh pass) (2) Medium oil: Decrystallized anthracene oil used for pre-sulfurization (3) Slurry concentration: 40Wt% (4) Catalyst concentration: Fe / DAF = 0.03 (weight ratio) S
/Fe=1.2 (atomic ratio) (5) Reaction pressure: 170 kg / cm ² H ₂ flowing (6) Reaction temperature: 450 ° C. (7) Reaction time: 80 minutes Iron ore crushed to an average particle size of 15 μm ( Robliber, Fe
64.7Wt%) and decrystallized anthracene oil, powder S
(200 mesh pass) was charged into the mixing tank 2 and pre-sulfided. Then, Taiheiyo charcoal and powder S were added to prepare a slurry. Transfer to measuring tank 3 and paste pump 5 from circulation line.
Then, it was fed into the reactor 7 through the preheater 6 and continuously operated for 50 hours. The temperature gradient between the inlet and outlet of the preheater is 18
It was 0-410 degreeC. The slurry discharged from the reactor was separated by the gas-liquid separator 8 and the liquefied crude oil was extracted into the storage tank 9. The gas leaving the gas-liquid separator was discharged through the mist separators 10 and 11. Table 1 shows changes over time in the pressure loss of the slurry preheater during operation.

[0023]

[Table 1]

It was found that without pre-sulfurization, the pressure loss gradually increased with the liquefaction time as shown in Table 1, and continuous operation for a long time was not possible. In the open inspection after the completion, there was a considerable blockage due to adhesion to the pipe wall, bottom, etc., but no scale adhesion was observed when presulfiding was performed.

[0025]

The method of the present invention enables continuous operation for a long period of time without closing the preheater of the slurry, but in order to achieve the purpose of this kind, synthetic pyrite (FeS ₂ ) Was the most effective catalyst, but the biggest drawback is the high production cost. INDUSTRIAL APPLICABILITY The present invention enables the use of much cheaper iron ore.

[Brief description of drawings]

FIG. 1 is a process diagram of a pre-sulfurization and coal liquefaction apparatus of Example 1.

[Explanation of symbols]

 1. Hydrogen compressor 2. Mixing tank 3. Weighing tank 4. Circulation pump 5. Paste pump 6. Preheater 7. Reactor 8. Gas-liquid separator 9. Storage tank 10. Cyst separator 11. Cyst separator 12. Storage device 13. Gas meter

Claims (1)

[Claims] 1. A method for preventing clogging of a slurry preheater, which comprises using a pre-sulfided metal oxide as a catalyst in a coal liquefaction reaction.