JPS63134028A - Dry desulfurizing method - Google Patents

Abstract

PURPOSE:To simultaneously perform desulfurization and dust removal of reducing gas in the same vessel by passing sulfide-contg. reducing gas jetted with iron oxide powder through a deposited layer of iron oxide formed on the surface of a filter consisting of porous ceramic. CONSTITUTION:An absorbent layer 2 is formed by depositing iron on the surface of a filter 1 consisting of porous ceramic. H2S incorporated in reducing gas is absorbed and removed by the following reaction equation when it is passed through the absorbent layer 2 consisting of iron oxide. Fe2O3+2H2S+H2 2FeS +3H2O. Since the particle diameter of the used absorbent is regulated to 10-100mu and is very small, the surface area per unit volume is large and also the contact time is made short and the usage of a desulfurizing agent is reduced. Further in the above-metnioned reaction, since only the surfaces of iron oxide particles are allowed to react, the smaller the particle diameter is, the larger the absorption capacity per unit volume is made and the utilization factor of iron oxide is enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a desulfurization method, and in particular to a method for removing sulfides from reducing gas produced by gasification of hydrocarbon fuel under high temperature and high pressure conditions. Regarding how to.

[Conventional technology]

The soaring price of crude oil and the heavier imports of crude oil are bleaking the future outlook for Japan's energy and chemical raw materials. As a solution to this problem, consideration is being given to gasifying the residue obtained by distilling light components from crude oil, so-called distillation residue, or coal as a raw material, and using the resulting carbon monoxide (CO) and hydrogen (H2). That is, C obtained in this way
o,)1. Policies for alternative energy to petroleum are being proposed, such as using it directly as fuel, or converting it to ethylene, propylene acetic acid, etc. obtained from petroleum (naphtha) in the future.

Sulfur compounds in heavy oil and coal are converted into sulfides and
It is mainly converted to H, 5 (approximately 10% COS) and mixed into the reducing gas of CO and H2. In addition to these H and S, the reducing gas also contains fine dust, that is, dust. Therefore, when used as fuel,
Since sulfur oxides and soot become a source of air pollution, and in the case of two synthetic raw materials, they poison the catalyst, two different purification methods have been proposed, and some of them are currently in operation.

One of them is a wet method, which removes hydrogen sulfide by chemical absorption.

This method allows hydrogen sulfide to be absorbed into the solution, so dust can also be removed at the same time, but the gas needs to be cooled, resulting in problems such as energy loss, regeneration of the absorption liquid, and wastewater treatment.

Another method is to absorb it into an absorbent (for example, iron oxide, molybdenum oxide, etc.) at a high temperature of 300 to 800°C, and then desorb it as sulfur oxide with oxygen and regenerate the absorbent. A so-called dry method has also been proposed, which involves repeated use. In this case, in addition to the above-mentioned desulfurization treatment, a dust removal treatment must also be performed, and therefore equipment related to the dust removal treatment must also be provided.

[Problem that the invention seeks to solve]

Iron oxide has been well known as a desulfurization agent. Iron ore itself has desulfurization performance as iron oxide, but a method has also been proposed in which iron oxide is supported on a heat-resistant carrier 2 such as silica, alumina, titania, etc. in order to be pulverized by adsorption and regeneration.

The inventors of the present invention encountered the first problem as a result of extensive research into a fixed bed dry desulfurization method using iron oxide as an adsorbent supported on a heat-resistant carrier.

The maximum amount of iron oxide Fe 203 that can be supported on a heat-resistant carrier is 30% by weight, and with a granular desulfurizing agent of about 3 mm, Fe2O3 can be adsorbed to a practical H2S removal rate of 80%. The response rate (utilization rate) is only 22%. In other words, since only 7% of the desulfurizing agent was used, it is necessary to prepare a large amount of desulfurizing agent.

In addition to the above-mentioned desulfurization treatment, a dust removal treatment must also be performed, and therefore equipment related to the dust removal treatment must also be provided. Especially in coal gasification combined cycle power plants, 40
It is necessary to perform dust removal under high temperature and high pressure conditions of 0 to 500'C and 10 to 3 Q ata, and existing electrostatic precipitators and back filters cannot be used, so a dedicated dust collector was also developed in addition to the desulfurization equipment development mentioned above. It's inside.

[Means for solving problems]

The present invention removes sulfides by injecting iron oxide powder into a reducing gas containing sulfides, mainly H2S, and passing the reducing gas through a deposited layer of iron oxide formed on the surface of a filter made of porous ceramics. This is a dry desulfurization method characterized by:

Here, the dry absorbent for removing sulfides in the method of the present invention is granular iron oxide, and the appropriate particle size of the granules is 10 to 100 microns. In addition to this absorbent component, other inorganic components such as alumina may be added in consideration of breathability, adhesion, and prevention of moisture absorption.

Silica, alumina silicate, zeolite.

(diatomaceous earth, perlite, feldspar, white clay, etc.) can also be added.

In the present invention, a porous ceramic filter is used to form the deposited layer of the absorbent. Here, FIG. 1 is an external view showing one example of a porous ceramic filter according to the present invention.

FIG. 2 is a partial longitudinal cross-sectional view of the filter of FIG. 1, showing the state of the ceramic filter during desulfurization.

In FIG. 1, 1 is a cylindrical filter made of porous ceramics with an absorbent deposited on its surface. In Figure 2,
Reference numeral 2 denotes an absorbent layer deposited on the surface of the porous ceramic filter body 3. Examples of the porous ceramic filter body 3 include cordierite, mullite, zirconia, alumina, silica, silicon carbide, silicon nitride, and sialon. In the figure, G1 is raw gas containing sulfides such as H and S and dust,
G2 communicates with the absorbent deposit layer 2 and the filter main body 3,
It is a processed clean gas.

[Effect]

It is thought that hydrogen sulfide H and S in the reducing gas are absorbed and removed by a quadratic equation when passing through the absorbent layer 2 made of iron oxide.

Fe20s + 2H, S + H2→2Fe S +
3H20 The absorption rate of the absorbent used in this method increases as the contact area with the raw gas increases.1 The particle size of the absorbent used in the method of the present invention is extremely small, 10 to 100μ, so the surface area per unit volume is The number of contacts is huge, so the contact time is short.

The amount of desulfurization agent used can be reduced. Further, in the above reaction, only the surface of the iron oxide particles reacts, so the smaller the particle diameter, the larger the absorption capacity per unit volume, that is, the utilization rate of iron oxide improves. Also from this point of view, the method of the present invention using fine particles is effective.

It is a well-known fact that in desulfurization reactions using iron oxide as an absorbent, the smaller the particle size of iron oxide, the more advantageous it is. However, if fine particles are included in the gas after desulfurization, it can cause clogging of pipes downstream. The main body of the filter used in the present invention is made of porous ceramics with sufficient heat resistance, which traps and absorbs powdered iron oxide on its surface. At the same time as forming a deposited layer of the agent, it also collects dust in the raw gas, similar to a pre-coated bag filter.

Note that the absorbent and dust collected and deposited on the filter body are usually backwashed and the supply of raw gas is stopped, and conversely, clean gas is vented from the processing gas side. brush it off.

Iron sulfide, partially unreacted iron oxide, and dust taken out from the desulfurization equipment are reacted with air, and the regenerated iron oxide is separated and used again as an absorbent.

According to the present invention, desulfurization and atom removal of the reducing gas can be performed simultaneously in the same container.

[Comparative example]

Commercially available titanium oxide [anatase type Tt 02].

Spherical 2-4 in: ] with 76 wt% TiO2 1Fe
It was impregnated with an aqueous ferric nitrate solution to a concentration of 24% by weight as 203, dried, and then baked at 450°C for 3 hours to obtain a sorbent.

Absorbent prepared by the above method 2 s, 1 t (20 m6
) was carried out under the test conditions shown in Table 1 by filling a small reactor with granular absorbent as shown in Figure 3 and carrying out a desulfurization test.

In the figure, 4 is a quartz reaction tube, and 5 is a granular absorbent.

6 is a ceramic porous plate.

Note that G1 in Figure 1 is the raw gas shown in Table 1, and G2 is the processing gas that has passed through the granular absorbent layer.

Curve A in Figure 5 shows the state of H2S adsorption in this test.
It was shown to. The H2S adsorbed until the H2S removal rate reached 77% was 16.8 mmol and f? -0 [Actual case] After drying the ferric nitrate aqueous solution used in the comparative example, it was heated to 450°C.
After firing for 3 hours, iron oxide was first obtained. This iron oxide was crushed and passed through a 35o mesh sieve.To 6.07 (2 ml) of powdered iron oxide, 0.69 pearlite with an average particle size of 20μ was added, and a cake layer was placed on the ceramic filter on two discs. I made it. Using this powder absorbent layer consisting of a cake layer, a desulfurization test was carried out by installing the cake-like absorbent layer in a small reactor as shown in Figure 4 under the same test conditions as in the comparative example shown in Table 1. went. In the figure, 7 is a cake-like absorbent layer made of powdered iron oxide, and 8 is a porous ceramic filter. The composition of this filter is mainly 3A lx
Os・2SiO2 (mullite), a small amount of 5in2
Contains, porosity = 32%, pore diameter (nominal) = 1
00μ, plate thickness = 7 rra. The state of H7S adsorption in this test is shown in curve B in FIG. At this time, the adsorption H and S were 40.2 m molf.

From FIG. 5, it can be seen that the adsorption time for maintaining the H, S removal rate of 80% or more was 314 minutes for the powder absorbent of the present example, compared to 116 minutes for the comparative example, which was significantly improved. Especially until the 250th minute, it's H, S! Once.

599 m or less, and showed desulfurization performance that completely removed H2S.

In addition, in this test, as the inlet gas G1 in Fig. 4, Is'
Table 2 shows the results of measuring the dust removal performance when dust of /Nrn' was entrained.

As is clear from the table, the dry desulfurization method according to the present invention exhibited an excellent dust removal function as well as a desulfurization function.

〔Effect of the invention〕

According to the dry desulfurization method of the present invention, iron oxide powder is injected into a reducing gas containing sulfide, and the reducing gas is applied to a deposited layer of iron oxide formed on the surface of a porous ceramic filter. It is possible to provide a gas treatment device that can remove sulfides with high efficiency by allowing the gas to pass therethrough, and also has a dust removal function at the same time.

[Brief explanation of the drawing]

Figure 1 is an external view of the porous ceramic filter used in the present invention, Figure 2 is a partial cross-sectional view of the filter in Figure 1 cut in the longitudinal direction, and Figure 3 is granular absorption in the desulfurization test explained in the comparative example. Explanatory diagram showing the filling situation of the agent, No. 4
The figure is an explanatory diagram showing the situation in which the powdered absorbent according to the example of the present invention was deposited in a cake shape during a desulfurization test.
The figure is a diagram showing the results of a desulfurization performance test according to the present invention.

Claims (1)

[Claims] Inject iron oxide powder into reducing gas containing sulfide,
A dry desulfurization method characterized in that the reducing gas is then passed through the deposited layer of iron oxide formed on the surface of a filter made of porous ceramics to remove sulfides.