JPS6169891A - Desulfurization of coal material - Google Patents

Abstract

PURPOSE:To remove sulfur contained in coal material and improve its quality, by mixing iron oxide into a reaction system of a fluidized bed gasification of coal material. CONSTITUTION:A sulfur-contg. coal material in powder or granule (coal, coke, etc.) is placed in a processing vessel together with an iron oxide (e.g. iron ore as iron oxide source) and water vapor is blown into the system, while temp. and pressure are kept at 850-1,000 deg.C and 1-10kg/cm<2>G, respectively, so that H2O/H2+H2O ratio in cracked gas may be 0.4 or higher by volume. The mixing of iron oxide promotes shift reaction of the formula during gasification reaction to a marked extent and reaction proceeds with decreased CO content of produced gas, marked increase of H2 ratio and increase of H2S concentration. The control of amounts of water vapor and oxygen blown into the system prevents lowering of desulfurization effect due to formation of FeS as a result of reaction of reduced iron with H2S caused by too high an H2 content. Thus the sulfur content of coal material is reduced to about 2% or lower.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an improved desulfurization method that can efficiently remove sulfur contained in carbon materials such as coal and coke and improve the quality of the carbon materials. It is about the method.

[Conventional technology]

A large number of technologies have been provided to date to desulfurize carbonaceous materials such as coal and coke, but the current mainstream method is to convert sulfur in carbonaceous materials into hydrogen sulfide and remove it. . However, this mild desulfurization method requires a large amount of hydrogen, and in most cases requires a long reaction time of several hours to over ten hours. Also, Ca in the carbonaceous material
Many studies have been conducted to improve the desulfurization effect by adding desulfurization agents such as O and MgO, but this has not been put to practical use because of problems in separating and post-processing the desulfurization agent.

Furthermore, methods of injecting ammonia or pre-treating carbonaceous materials with NaOH have been proposed in order to improve the desulfurization effect, but these methods cannot necessarily be said to be advantageous in terms of cost and operability.

On the other hand, research on decomposing and gasifying carbonaceous materials using a fluidized bed method has been conducted for a long time, and many improvements have been proposed. Gasification of carbonaceous materials using the fluidized bed method is generally carried out using steam and oxygen. Steam is used as a reforming gas, and oxygen is mainly used for burning carbonaceous materials to supply reaction heat. be done.

In the gasification of carbonaceous materials by steam, equal volumes of H2 and CO are first generated by the water gasification reaction shown in the following equation (0), and C+H20→ CO+H2... (II) Also, due to the reaction between oxygen and carbonaceous materials, )The following reaction], the reaction of equation (2) occurs], and in the high temperature range, the [sword reaction also occurs].

C+ O2 → co2 ... [■] C+ 'A
O□ →co ・・・mark〕C+ CO2→
2CO... mark] Also, the generated CO further causes a steam shift reaction as shown in the CD equation and is converted into hydrogen and 002.

Co+H2O→CO2+Ht...[71 Under higher pressure, the generated hydrogen reacts with (1'D, ([1<C-?CO) to produce methane.

C+2H, →CH,... [℃ CO+3H, →CH, +H,0・-kuI By the way, in the normal gasification reaction (the reaction of formula D~(equation) mainly occurs), the Ht proportion in the produced gas is The ratio is 20-40%, C
The ratio of O is said to be about 20 to 50 inches. It is thought that the reaction of formula [71] also occurs to some extent, but the proportion thereof is small, and the reaction of formula (In, (V[]) is promoted under high pressure conditions, but at 10 kg/C
I? At pressures below It, the production rate of methane is extremely low, at a few degrees or less.

In any case, when gasifying carbonaceous materials, the first objective is to gasify as much carbonaceous material as possible. Since the residue after gasification contains a large amount of sulfur, when used as solid fuel, a large amount of SOX is produced in the exhaust gas.
This causes problems such as air pollution and acceleration of corrosion of ancillary equipment, and when used as a carbon source for iron making, the problem of increased sulfur content in hot metal arises.

[Problem that the invention seeks to solve]

Based on the above-mentioned known techniques, the present invention aims to provide an improved method for the former desulfurization of carbonaceous materials, but the starting point was a method for improving the desulfurization of carbonaceous materials using a fluidized bed method. This is a new knowledge obtained from the carbonization technology, namely the fact that ``desulfurization of carbonaceous materials progresses significantly when iron oxide coexists in the gasification reaction system of carbonaceous materials.'' The present invention utilizes this knowledge to provide a novel desulfurization technology for carbonaceous materials using iron oxide such as iron ore.

[Means to solve the problem]

In the present invention, granular carbonaceous material containing sulfur is charged into a processing container together with granular iron oxide, and the H
The gist lies in blowing water vapor and oxygen into the treatment system so that t O/(H20+Hz ) has a volume ratio of 0.4 or more.

[Effect]

According to the inventors' preliminary experiments on fluidized bed gasification of carbonaceous materials, when powdered iron ore is mixed into the fluidized bed of carbonaceous materials, the CD shift of the gasification reaction occurs. The reaction is significantly promoted, CO in the produced gas decreases, the Ht ratio increases significantly, and at the same time the degrees of KH and SJ also increase. That is, due to the coexistence of iron ore, the desulfurization reaction of the carbonaceous material progresses, and sulfur is removed as H and S. However, if the H2 concentration in the generated gas is too high, iron sulfide will be produced by the reaction between metallic iron produced by the reduction reaction and hydrogen sulfide (Fe+H2S # FeS+H2), and the iron sulfide will gradually accumulate in the reaction system and become carbon. The desulfurization effect on the material decreases. However, it has been confirmed that if the reaction conditions are controlled so that the H2 concentration in the produced gas is below a specific value, the production of iron sulfide can be suppressed and the desulfurization of the carbon material can proceed efficiently. The most effective way to suppress the H7 concentration is to adjust the amount of steam injected as reformed gas. It is only necessary to adjust the amount of steam and oxygen blown so that the volume ratio is less than 2 or more, and the sulfur content of the carbon material can be reduced to about 2% or less. Since the sulfur content of the oil coke used as a fuel coke is said to be less than 2%, the above method can yield a low-value carbonaceous material useful as a raw material for blast furnace injection.The pressure in the reaction system is 1 to 10 kg/crr to promote desulfurization effect
It should be set within the range of FG. Also, the temperature is 850℃
It should be set above 850° C., and the equilibrium reaction for desulfurization will not proceed efficiently. However, if the reaction temperature is too high, a sticking phenomenon (
Since a phenomenon in which the fluidization of the fluidized bed stops may occur, it is preferable to suppress the temperature to about 100°C or less.

In addition, mill scale, dust, etc. can be used as a substitute for the iron ore as the powdered iron oxide, and a part of these may be mixed with the iron ore. Furthermore, the particle size of the iron oxide is 30~ It is best to use one adjusted to 500 μm.

〔Example〕

The inventors have confirmed through experiments that when powdery iron ore is allowed to coexist in the reaction system when carbon material in a fluidized bed is gasified by steam, the following results are produced. It has become clear that as the hydrogen concentration in the gas increases, large amounts of H and S are produced by the desulfurization reaction. Incidentally, Table 1 shows the composition of the produced gas when fluidized bed gasification is performed under the following conditions (using carbonaceous material alone and using carbonaceous material and iron ore in combination).

[Reaction conditions]

Reaction temperature = 900°C Reaction pressure Crab 5kg/cffItG Iron ore/charcoal material: 85/15 or 100/Q (weight ratio)
Nisteam 100% as gas and other agents Gasifier: See Figure 1 (88Mφ) As is clear from the comparison of the generated gas composition in Table 1, when iron ore is used together, CO in the generated gas decreases and H7 It is clear that the shift reaction of the above formula [Ma] is promoted as the ratio of . The degree of HtSm in the generated gas has increased significantly, and the desulfurization reaction of the carbonaceous material has progressed considerably. By the way, according to the results obtained in the above experiment, approximately 33'M of carbonaceous material was gasified by the combination of iron ore, but the initial S content in the carbonaceous material was 5.5%. However, the amount decreased to 1.6% by weight after the gasification reaction. Since the S content of commercially valuable carbonaceous materials is generally considered to be about 2% or less, this method can be fully utilized as a desulfurization method for carbonaceous materials. In addition, if the surface quality time of the carbon material is increased, the desulfurization reaction will proceed further, but on the other hand, the consumption of carbon material due to gasification will also progress, so the residence time is determined by considering the balance with the target yield of low value carbon material. do it.

In this way, when iron ore coexists in the fluidized bed gasification reaction system of carbonaceous materials, the desulfurization reaction of the carbonaceous materials progresses, but on the other hand, the reduction of iron ore progresses due to the increase in H2 concentration due to promotion of the shift reaction, and metallic iron is produced. reacts with hydrogen sulfide in the reaction system to produce iron sulfide.

Fe+H2S q FeS+H.

Therefore, if iron ore is recycled as a melting medium for desulfurization reaction,
Iron sulfide gradually accumulates. And H.

As the gas is consumed for iron sulfide and desulfurization, the desulfurization effect on carbonaceous materials cannot be sufficiently exerted.

If the iron ore is in the state of hematite or magnetite, sulfidation of iron components can occur from an equilibrium perspective, and even if it is reduced to the wustite stage, sulfidation will not occur at the a2sa degree obtained in the above experiment. . However, when iron ore is reduced to metallic iron, there is a possibility that it will react with H and S to produce FeS. Therefore, if the production of metallic iron by reduction of iron ore is prevented, the production of FeS can also be necessarily prevented. From this viewpoint, various reaction conditions were investigated, and it was confirmed that the production of metallic iron could be prevented if the H2 ratio in the produced gas was kept low. In other words, Figure 2 is a graph showing the reduction equilibrium relationship of iron oxide in a mixed gas of H2 and H,0), and the reduction state of iron oxide is determined by temperature and Hz O/(Ht O+Ht).
Since it is determined by the ratio, the generation of metallic iron can be prevented by appropriately adjusting the generated H2 ratio and the amount of steam introduced.

By the way, in a fluidized bed reaction, since the reaction is operated at a terminal velocity below the terminal velocity (that is, the critical gas flow velocity) at which the fluidized particles fly out of the fluidized bed, there is an upper limit to the amount of steam blown into the reactor. When gasification is carried out at normal pressure, the ratio of H2 generated when steam is blown in at an appropriate flow rate and unreacted H20 is the same as shown in ■ in Figure 2. This may occur. By the way, ■ when performing gasification experiments at normal pressure and 900°C! The ratio of 20/(I(20+H2)) was approximately 035, and the analysis results of the iron ore showed that approximately 20 parts by weight of metallic iron had been produced.Moreover, X-ray diffraction confirmed a significant amount of FeS in the phase. It was confirmed that sulfur was migrating to the iron ore side. However, as is clear from Figure 2, the gas composition must be adjusted so that the H, WH20 + HD ratio in the reaction system is 0.4 or more. If possible, it is possible to eliminate the formation of metallic iron.Therefore, the reaction system H20/
As a result of conducting research to find a method that would allow the (H20+H2) ratio to be 0.4 or higher, it was concluded that the pressure in the reaction system could be increased. In other words, if the pressure of the reaction system is increased, the amount of steam blown can be increased in proportion to the pressure even if the gas flow rate is the same, whereas the gasification rate of carbonaceous material is almost constant, almost unaffected by pressure, and the amount of steam produced is H4 remains unchanged.

Therefore, if the reaction pressure is increased and the amount of steam blown is increased, the H2 intensity of the reaction system can be relatively lowered and the H20/(H3O+H2) ratio can be increased. For example, when the fluidizing gas flow rate is kept constant at 40 cm/sec, as the pressure increases, H2
The 0/(H20+H2) ratio gradually increases, and at 51(g〆)G, it is completely in the Fe, O, stabilization region.

In this way, if the pressure of the fluidized bed gasification reaction system is increased and steam is injected so that the Hto/(H, o+at) ratio of the produced gas becomes 0.4 or more, metallic iron can be produced by reducing iron ore. Iron ore can be effectively used as a catalyst for desulfurization of carbonaceous materials without causing deterioration of the desulfurization effect due to generation and accumulation of iron sulfide. Moreover, iron ore can easily be used as Fe, 03(
(hematite) to pesoa (magnetite), the carbonaceous material and iron ore after desulfurization treatment can be easily separated by magnetic separation, and the iron ore can be recycled as a desulfurization catalyst. However, if the pressure of the reaction system is too high, the methanation reaction shown in the formula (Ll, [:V2O) will be promoted, H2 gas will be consumed, and the desulfurization effect will decrease, so the pressure should be 1 to 10 kg/ It is preferable to set the reaction temperature to about 850°C or higher to allow the gasification reaction of formula 13 and the shift reaction of CD formula to proceed efficiently. 1000℃ to prevent sticking caused by iron ore fusion.
It is best to keep it below a certain level.

FIG. 3 is a flow diagram showing a typical example of carrying out the carbonaceous material desulfurization method of the present invention, in which powdery carbonaceous material and iron ore are charged into a fluidized bed reactor l from the upper part, and steam ( Gasification and desulfurization reactions of the carbonaceous material proceed in a fluidized state while blowing in a small amount of oxygen). The reaction conditions in this case are appropriately adjusted according to the above explanation. The generated gas is then sequentially extracted out of the furnace, while a mixture of carbonaceous materials and iron ore is extracted little by little from appropriate positions in the fluidized bed. And then separate the carbonaceous materials and iron ore through magnetic selection? 9 In addition, the iron ore is circulated as a desulfurization medium, and the desulfurized carbonaceous material is sequentially extracted as a product.

By recycling iron ore as a catalyst in this way, carbonaceous materials can be efficiently desulfurized. In the present invention, as mentioned above, the gasification and desulfurization reactions of the carbonaceous material proceed in parallel, but the more you try to reduce the sulfurization of the carbonaceous material, the higher the gasification rate and the lower the recovery rate of the low-value carbonaceous material. is decreasing. Therefore, the residence time etc. may be adjusted according to the target sulfur concentration of the carbonaceous material, and the generated gas may be subjected to denaturation, dehydration, etc. as necessary, and then used as fuel, reducing gas, etc.

〔Effect of the invention〕

The present invention is carried out as described above, but the point is that by coexisting iron ore in the fluidized bed gasification reaction of carbonaceous materials, desulfurization of unreacted carbonaceous materials can proceed efficiently, and the carbonaceous materials can be desulfurized efficiently. It has now become possible to establish a new desulfurization technology for wood.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the experimental method of fluidized bed gasification, Fig. 2 is a graph showing the gas composition in the reaction system and the reduction equilibrium state of iron ore, and Fig. 3 is a flow diagram showing an example of the present invention. It is.

Claims (1)

[Claims] Powdered carbonaceous material containing sulfur is charged into a processing container together with powdered iron oxide, and the temperature is set at 850-1000°C and the pressure is set at 1-10°C.
H_2 in decomposition gas while maintaining kg/cm^2G
A method for desulfurizing carbonaceous materials, characterized by blowing steam and oxygen into a treatment system so that O/(H_2+H_2O) has a volume ratio of 0.4 or more.