JPS61283340A - Preparation of desulfurization agent for fluidized bed apparatus - Google Patents

Abstract

PURPOSE:To obtain a desulfurization agent also used as a fluidizing medium having excellent capacity inexpensively, by mixing a specific amount of a limestone powder and/or a dolomite powder with the collected ash of the dust collector of a fluidized bed combustion furnace and adding water to the resulting mixture before granulating said mixture. CONSTITUTION:As the collected ash of the dust collector of a fluidized bed combustion furnace, one discharged from a fluidized bed combustion furnace using a CaO or CaO-MgO type desulfurization agent and collected by a dust collector is pref. At first, 10-90wt% of a limestone powder and/or dolomite powder with a particle size of 48 mesh or less is mixed with said collected ash and water is subsequently added to the resulting mixture while the moistened mixture is granulated into pellets pref. having a particle size of 1-3mm by a tumbling type granulator to obtain a desulfurization agent for a fluidized bed apparatus. By this method, collected ash can be effectively put to practical use and the desulfurization catalyst also used as a fluidizing medium having excellent capacity can be continuously prepared in a mass production system.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to reducing SO2, H,
The present invention relates to a method for producing a removing agent.

[Prior art] Fluidized bed heating furnaces are used in various fuel furnaces and cities due to their advantages such as the ability to use low-quality fuel, coarse fuel, low NOx value operation, easy desulfurization of exhaust gas, and low equipment costs. They are increasingly being used in fields such as dust and sludge incinerators and solid fuel gasifiers. The recent rise in energy costs has made it essential to burn fuel with a high sulfur content or to gasify solid fuel with a high sulfur content, which inevitably increases the sulfur concentration in the exhaust gas or produced gas. In addition, since urban dust sludge, which is mainly composed of human physiological or domestic waste, contains sulfur at a high concentration, the sulfur concentration in the exhaust gas during incineration is high and causes air pollution.

Currently, there is a desire for a healthy harmony between industrial activities and human life, and there is a strong demand for the development of a high-performance, inexpensive, and easily handled desulfurizing agent. On the other hand, various types of ash are discharged from fluidized bed combustion furnaces currently in operation, especially dust collection bags!
The ash collected in the ash has small particles and is bulky, so there is a big problem in the disposal of the ash.

Co
o or natural carbonate minerals whose main component is MgO, and industrial products whose main component is CaO, such as portland cement clinker, hydrated hardened portland cement, or hardened portland cement and limestone. Limestone and dolomite have advantages and disadvantages in that they can be obtained at low cost, but limestone and dolomite, which are aquatic rocks, contain water and are dense, so they are difficult to use as a fluid medium. It has the disadvantage of collapsing and producing a large amount of scattered dust. Also, limestone and dolomite become porous when decarboxylated at high temperatures. However, since the pores created by decarboxylation are minute, the micropores are blocked by the reaction products with S02 or H2S that occur afterwards, and So or H2S
The reaction of the desulfurizing agent with the surface occurs only on the surface and in the vicinity of the surface, which has the disadvantage that a desired desulfurization rate cannot be obtained unless a large amount of the desulfurizing agent is used.

Cement clinker is usually fired at a high temperature of 1450° C. or higher to become dense and the main component is calcium silicate.

Therefore, although it has the strength as a fluid medium, So2
Alternatively, since the reactivity with Has is significantly lower than that of CaO or MgO, the desulfurization performance of cement clinker is significantly inferior to that of limestone or dolomite.

The main component of the hardened Portland cement is CaOS
i Ot H20-based hydrate and Ca (OHL,
When heated above 500°C, it becomes mainly calcium silicate and CaO. This CaO has extremely high reactivity with So2 or H2S, but usually only about 15 to 25% is produced, resulting in poor desulfurization performance as a whole. However, its stability as a fluid medium at high temperatures is excellent.

Desulfurization agents made by hardening limestone or dolomite powder with cement have the advantage of excellent desulfurization performance and stability at high temperatures, but they have the disadvantage of being expensive because they use Portland cement as a raw material. are doing.

As mentioned above, the ash collected by the dust collector in the fluidized bed combustion furnace is fine particles and bulky, so it may cause dust pollution or increase transportation costs, so it is difficult to use the ash effectively or to make it cheaper. Establishment of processing technology is strongly desired.

[Problems to be Solved by the Invention] The present invention provides a fluidized bed apparatus that has excellent desulfurization performance and can remove Sol, H, and S from gas by using the ash collected by a fluidized bed combustion furnace dust collector. It is an object of the present invention to provide a method for manufacturing a fluid medium at low cost using simple equipment.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for producing a fluidized medium with desulfurization performance for a fluidized bed apparatus, in which limestone powder, limestone powder, Another object of the present invention is to provide a method of producing a dolomite powder by mixing the dolomite powder or both in an amount of 10% by weight or more and 90% by weight or less, adding water, and granulating the mixture.

[Effect] The ash used in the present invention is CaO or Cao-Mg.

Ash collected by a dust collector discharged from a fluidized bed combustion furnace using a desulfurization agent is preferable.
There are S O4, Cao, CxA, C4A F, etc., and when hydrated, the entry guide (C, A・3 Ca
It has hydraulic properties because SO + 32H20) is generated,
It is a fine powder containing approximately 90% of ash of 10μ or less, exhibits a Blaine specific surface area of 10,000 or more, and is preferable because it hardens when mixed with water.Ashes other than the above that come out of a fluidized bed combustion furnace are granular (1 to 31). For example, overflow ash discharged from a fluidized bed combustion furnace cannot be used as it is, so it is undesirable.
Further, the dust collector-collected ash (fly ash) discharged from the pulverized coal combustion furnace is not preferable because it lacks hydraulic properties when used alone.

The limestone and dolomite powder used in the present invention should preferably have a mesh size of 48 mesh or less; a mesh size of 48 mesh or more is not preferable because the desulfurization performance and granulation properties deteriorate.

The amount of limestone or dolomite powder added to the collected ash of the fluidized bed combustion furnace dust collector is preferably 10% by weight or more and 90% by weight or less. If it is less than 10% by weight, the desulfurization performance will decrease.
Moreover, when it exceeds 90% by weight, the strength of the desulfurizing agent decreases, which is not preferable.

The molding is preferably carried out by a transfer granulation method.

Extrusion molding is not preferred because continuous operation is difficult due to problems such as controlling the amount of water added and curing within the extruder.

As the transfer type granulator, any type of granulator such as a pan type, a drum type, or a cone type can be used. The size of the molded product (pellet) is preferably 1 to 3I, lsg.

The following cases are not preferred because they tend to scatter when used as a heat medium. Moreover, when it is 31 or more, desulfurization performance deteriorates, which is not preferable. Although the pellets can be used as a desulfurizing agent as they are, it is preferable to use them after drying; however, it is not preferable to use the pellets after drying, since the pellets will burst if they are thrown into a fluidized bed combustion device without drying.

Experimental example-1 Fluidized bed combustion furnace dust collector collection ash (hereinafter abbreviated as FA) and limestone powder with the chemical components listed in Table-1 were mixed at varying blending ratios, and a small pan pelletizer (φ= 600
L1++*) was used to granulate pellets of various sizes. The pellets were then dried in IIO'C and then sieved to prepare pellets of 2.00 to 2.36 s+m.

The particle sizes of the FA and limestone used are shown below: FA: 20μ or less 95% limestone powder:
250 mesh or less 91%: - Item Chemical component raw material Tgloss In5ol 5iOz
^1203 Fe2O, CaOMgO503F^
F, 8 14.9 1B, 5 16.9
5.3 29.0 4.5 5.0 Limestone
42.4 0.2 1.5 0.9 0.6 53
．． 4 Fill a fixed bed with 2 g of 0.7 tr pellets and
An SO2 or H2S absorption test was conducted by passing a gas containing O2, H, or S. For comparison, limestone was crushed and sieved to prepare particles of 2.00 to 2.36 mm, and an SO2 or H2S absorption test was conducted in the same manner.
It took 10 minutes for H2S and 9 minutes for H2S.

So! The conditions for the absorption test were: gas composition: SO2706ppm, 0251 COw
l 2%, remaining N1, gas flow 12117 minutes, fixed bed cross-sectional area near, 07en2, fixed bed temperature = 850°C
The conditions for the H2S absorption test were: gas composition: H2S E'50ppn+, remaining N2° gas flow 12,117 minutes, fixed bed cross-sectional area +7.07cm", fixed bed temperature: 850°C
It is.

The desulfurization rate shown in the figure was calculated using the following formula: However, in the above formula, 'SO2/H2SJ is 'Sow or H2S.
J, and the inlet concentration and outlet concentration are the concentrations in ppm of SO□ or H2S at the inlet or outlet, respectively.

The vertical axes in Figures 1 and 2 indicate the time during which the desulfurization rate was maintained at 80% or more, and the horizontal axes indicate the amount of limestone powder added.
The figure shows the results of the S02 absorption test, and Figure 2 shows the results of the H and S absorption test.

It can be seen from FIGS. 1 and 2 that the desulfurization performance is significantly improved when limestone powder is added to FA.

It can be seen that the amount of limestone added is preferably 10% or more.

Experimental Example-2 1,19-1.68m prepared as in Experimental Example-1
- A fluidization test was conducted on the pellets to measure the amount of pellet wear due to fluidization, and the results shown in Figure 3 were obtained.

The conditions for the fluidization test are as follows: Fluidized bed temperature: 2850°C, Fluidization gas: Air flow cross-sectional area near, 07 cm', Layer thickness of input pellets: 50+*Fluidization speed: 0.7 m/sec, Fluidization Time: 2 hours From FIG. 3, it can be seen that as the amount of limestone powder added increases, the amount of pellet wear increases significantly.

It can be seen that the amount of limestone powder added to FA is preferably 90% or less. - Experimental Example-3 The dolomite powder described in Experimental Example-2 (150 mesh or less, 89z) and FA (20μ or less, 84%) were mixed in a weight ratio of 2 parts of dolomite powder and 1 part of FAI.
In the same manner as i, pellets 1 to 31 were made vl and actual examples-
SO□ absorption test and fluidization test were conducted in the same manner as 1 and 2, and the following results were obtained: Old = 34 Item Chemical component raw material 1g1oss In5ol 5i02
^1203 Fe2O3CaOt4+rO503F
^ 19. o 18.514.014.93.721.
62.25.5 do 01ite 44.7
0.1 0.6 0.2 0.5
35.1 18.1 trS Oz absorption test results: Time during which the desulfurization rate was maintained at 80% or higher: 157 minutes Fluidization test results: Pellet loss amount: 4.0% [Effects of the invention: According to the manufacturing method of the present invention, the following Effective: 1) The ash collected by the fluidized bed combustion furnace dust collector can be effectively used; 2) A large amount of fluidized medium for the fluidized bed equipment, which has excellent desulfurization performance and excellent stability at high temperatures, can be used continuously. Can be manufactured.

[Brief explanation of the drawing]

Figure 1 shows the results of the S02 absorption test, and is a diagram showing the relationship between the amount of limestone powder added and the time for which a desulfurization rate of 80% or more was maintained. FIG. 3 is a diagram showing the relationship between the amount of time the desulfurization rate was maintained at 80% or more, and FIG. 3 is a diagram showing the relationship between the amount of limestone powder added and the amount of wear of the pellet.

Claims (1)

[Claims] A desulfurization agent characterized by mixing limestone powder, dolomite powder, or both in the ash collected by a fluidized bed combustion furnace dust collector in an amount of 10% by weight or more and 90% by weight or less, and granulating the mixture by adding water. manufacturing method.