JPS6099920A - Agent for raising melting point of combustion ash - Google Patents

Abstract

PURPOSE:To absorb melted ash, raise a melting point of melting ash and to restrict its hindering item by a method wherein additive composed of a specific compound is formed to a ball shape with gloiopeltis glne, casein, Arabian rubber or solidifying agent of high molecule and then is fed at the peep hole in a boiler. CONSTITUTION:Additive agent composed of more than one Mg compound, Ca compound and Al compound or additive agent composed of more than one of these compounds and Si compound is formed to a ball shape with gloiopeltis glne, casein, Arabian rubber or solidifying agent of high molecule. Then, the additive agent is fed from the peep holes 12 arranged in the combustion chamber wall 11 of the boiler toward the melting ash 13 accumulated at the furnace bottom. With this arrangement, the material of the container is reached to the furnace bottom while it is being ignited, the melting ash is absorbed there and a chemical reaction is occurred with it.

Description

[Detailed description of the invention] The present invention relates to an agent for increasing the melting point of combustion ash.

In wheelers that use petroleum-based fuel, vanadium (V) is contained as an impurity in the fuel.

It is known that sodium (Na) and sulfur (S) are the main components and cause heat transfer problems and corrosion.

In particular, corrosion damage caused by fuel ash is often experienced in the so-called high-temperature parts of boilers such as superheater tubes and reheater tubes, and the cause is the accelerated oxidation effect of V compounds contained in the fuel ash. Because of this, it is also called vanadium attack. However, the melting point of the single compound is not so low (approximately 660°C for VtOs), and boiler tubes kept below this temperature are unlikely to suffer severe corrosion, and Na and S compounds usually coexist in fuel ash. Then, the melting point decreases to about 500 to 550°C, and the corrosivity becomes extremely severe. Corrosion damage caused by fuel ash is called vanadium attack, and Na'pS compounds also play an important role.

Generally, fuel ash, which is a product of V, Na, and S compounds, has a low melting point, but on the surface of the boiler tube to which it is attached, it becomes solid due to the cooling effect of water and steam flowing inside the tube.

Where it is strongly affected, it becomes a molten material and flows, flowing down the furnace evaporation tube or dripping to the bottom of the boiler.

If this phenomenon continues for a long time, molten fuel ash will accumulate at the bottom of the reactor. The bottom of the boiler is made up of evaporation tubes, so molten fuel ash (hereinafter referred to as
The upper layer (molten ash) is directly exposed to the combustion gas and its radiant heat, but the lower layer is exposed to the evaporator tube (660
~400°C), so there was no corrosion or wear.

However, recently, due to the deterioration of the fuel situation, it has become difficult to obtain high-quality fuel, and although the use of low-quality fuel requires exhaust gas treatment equipment (for pollution prevention purposes), the fuel cost is low. Many boilers use low-quality fuel. In such a boiler, the melting point of the fuel ash further decreases to below 500°C, and the molten ash that remains at the bottom of the furnace becomes more fluid due to the influence of the combustion flame, and in severe cases, it becomes like a whirlpool. It may flow.

As a result, some parts of the evaporator tubes forming the bottom of the furnace, where no abnormality was previously observed even when molten ash remained, are now showing signs of corrosion and wear and tear.9 If left untreated, serious accidents could occur. There is also a risk that it may be triggered.

As a countermeasure, compounds such as Mg and Ca are added to the fuel, and when the fuel is burned, they are chemically reacted with V, Na, and 8 compounds to raise the melting point of the fuel ash and suppress its corrosivity (fuel Ash exhibits very strong chemical reactivity when it is in a molten state, but has no reactivity when it is in a solid state.

Although this method exhibits certain effects, adding large amounts of Mg and Ca compounds (hereinafter simply referred to as additives) increases operating costs and causes undesirable phenomena in boiler operation. In other words, when a large amount of additives adheres to the furnace evaporation tube, the white color of these additives reduces the heat absorption of the evaporation tube, which suppresses the decrease in combustion gas temperature and causes the additive to move downstream. . For this reason,
The heat absorption balance of the boiler as a whole is disrupted, and the phenomenon that normal operation becomes impossible becomes apparent.

Therefore, when injecting additives, even when the purpose is to prevent corrosion of fuel ash, it is necessary to take into account the operating condition of the boiler at all times, and as a result, it is not possible to use a large amount of additives. It is not possible to completely prevent molten ash from accumulating at the bottom of the furnace.

One of the inventors previously proposed a method of coating the bottom of the furnace with a refractory material and an alkaline earth metal compound as a countermeasure to one such problem. (Jitsugan 53-03υ178)
This method is sufficiently effective when the molten ash remains at the bottom of the furnace, but even if inferior fuel is used, molten ash may not necessarily remain due to the boiler structure, combustion method, etc. Therefore, in such a case, it is inevitable that applying the method 1IJL coating of the prior art to the hearth bottom in advance will lead to an increase in costs.

In view of the above-mentioned current situation, the present invention has developed a system that incorporates a high melting point compound with physical adsorption performance in the bottom of the furnace after confirming from the beep hole that molten ash has started to accumulate at the bottom of the furnace after the boiler is operated. By introducing the ball-shaped container, the molten ash is absorbed and the melting point of the molten ash is raised to suppress the damage caused by the molten ash. Although this high melting point compound can be introduced in the form of powder, it is easier to reach the bottom of the furnace and more effective if it is contained in a ball-shaped container.

The present invention has been made in view of the above point KN, and includes an additive consisting of one or more of Mg compounds, Ca compounds, and 11 compounds, or an additive consisting of one or more of these compounds and a Si compound. The present invention relates to an agent for increasing the melting point of combustion ash, which is formed into a ball shape using cloth seaweed, casein, gum arabic, or a polymeric fixing agent.

The S1 compound may be porous or nonporous.

The features of the present invention will be explained below.

(1) M g (OH)2 r M as a high melting point compound
g O+ Mg cOsCab, Ca(OH)t *
The point of using A 120B is basically the same as conventional knowledge, but if it is put into the bottom of an operating furnace in powder form, the flow of combustion gas and air for combustion gas will cause the boiler to burn. The group moves into the furnace, but does not reach the desired bottom of the furnace. In the present invention, the ash is formed into a ball shape using a binding agent and then introduced through the beep hole, so the material in the container burns and reaches the bottom of the furnace, where it absorbs the molten ash and undergoes a chemical reaction. .

(2) All high-melting point compounds can be used, each alone is effective, and there is no harm in mixing them, but when mixing, it is preferable to include carbonate (MgCOs) so that they come into contact with the molten ash. In this case, the high melting point compounds are better mixed with the molten ash due to the pressure of Co and gas generated when the tori decomposes.

(3) Since the high melting point compound is formed into a ball shape,
With moisture in the air even when not in use! There is no contact, therefore the powder is agglomerated p, Mg(OH)z is M
Since there is no change in gC0, the quality is stable, but if CaO or the like is contained, it is advantageous from a safety standpoint.

(4) It is easy to handle and can be used when and in the required amount.

(5) As the fixing material for forming into a ball shape, funoori,
Casein, gum arabic and polymeric adhesives (e.g. commercially available water-soluble polymeric adhesives such as acrylic resin and vinyl acetate)
is used.

(6) The shape of the high melting point compound may be a powder, a lump, or a single grain, and there are no restrictions on the shape. In addition, the ball shape is not limited to a spherical shape, but may also be a chicken egg shape or a Zigbee ball shape.

(7) Compound 81 can also be mixed with the high melting point compound of (1) above. Porous Si compounds (for example, silica gel, bisque, etc.) generally do not chemically react with molten ash, but they physically adsorb molten ash, so they can capture molten ash that is several times its own volume. , has the effect of preventing the disorder. Moreover, since it can withstand relatively high temperatures, it will not lose its function even if it is thrown into molten ash. In addition,
The amount of Si compound added is 20 to 50 vr in the high melting point compound.
It is preferable to make it account for t%.

(8) The effects of the ball-shaped additive of the present invention on molten ash can be broadly classified as follows: ■ Mg, Ca, and Al compounds cause a chemical reaction with the molten ash components to produce a high-melting point compound; ■ Porous. The S1 compound physically adsorbs a large amount of molten ash and immobilizes it (adsorbed molten ash has no adverse effect, so Mg.

(requires less Ca compounds).

It aims to achieve its purpose by dividing it into two parts.

In addition, in the present invention, a non-porous Si compound (for example, 810!
) can also be used, and the non-porous sio, does not have the effect of ■■ above, but it has the effect of making the molten ash extremely brittle and making it easier to take out when discharging the molten ash outside the furnace after the boiler has stopped. effective.

The present invention can be advantageously applied to heavy oil combustion boilers and the like.

The agent of the present invention is introduced into the molten ash 15 remaining at the bottom of the furnace through a beep hole 12 provided in the combustion chamber wall 11 of the boiler shown in FIG. In addition, 14 and 15 are superheaters, and 16 shows the flow of combustion gas. For charging, compressed air may be used to fill the inside of a steel pipe with the agent of the present invention and blow it out. The introduced agent of the present invention burns due to the heat in the furnace and reaches the molten ash, and the porous 8102 adsorbs the molten ash, and the high melting point compound comes into contact with the molten ash and causes a chemical reaction, reducing its melting point. to rise. for example,
Mg compounds (MgO, Mg(OH)t
+ MgCO5), it reacts with the compound (■) in the molten ash, producing 2Mg0・V,O, (melting point 865℃),
5Mg0・Vt0Il (melting point 1.191°C) is produced,
Ca compound (Cab.

ca(OH),, caco3), 2CaO-
V2O5 (melting point 778°C) produces 3CaO-V20s (melting point 1.016°C), ■, 0. Single melting point (approximately 66
When the temperature is much higher than 0℃), the phenomenon of melting at the bottom of the furnace disappears. Moreover, when the boiler is stopped, the ash at the bottom of the furnace is very soft and can be easily discharged from the furnace. In addition, porous 5 in 1, for example, silica gel 11 is 5 to 10
It has the ability to adsorb F molten ash.

Experimental example 1 Use the following additives (1) to (4), funoori, and casein.

Gum arabic or a commercially available water-soluble polymeric adhesive (acrylic resin, emulsion type containing fine particles of vinyl acetate) was added, stirred well, formed into a ball shape, and allowed to stand.

(1) Porous S1O, containing (silica gel) Mg0
70 wt%, 5i02 (porous) 30 wt% (2
Unglazed (including porous porosity Mg050wt%, A11035vrt%.

Unglazed 45wt (3) Porosity 810. Does not contain MgO100
wt Chi (4) Porous S10. CaCO350wt%, Mg(OH), 50wt%
Due to the release of moisture into the atmosphere and subsequent drying, the ball-shaped mass becomes hard and is extremely easy to handle. In particular, those using a polymer adhesive form a thin polymer film on the outer surface of the pole, which also has a waterproof effect.

Add the additives (1) to (4) above to 1 kg of molten ash.
The increase in melting point was measured. The results are as follows: 5102. Additives containing bisque had the highest increase in melting point.

Type of fixing agent (melting point) Additive 0 agent Funori Casein Gum arabic Type of polymeric fixing agent (1) a2o s1!5 s05' 821 (2)
802 800 795 810(3) 745 74
1 745 740 (4) 770 76.0 761
766 (Note) The melting point of molten ash (before additive injection) is 548
It is ℃.

In addition, porous 5102. When unglazed ceramics and other materials are added with moisture or a fixing agent, they also adsorb them, but at high temperatures, these (
It is thought that all moisture, adhesives, etc. will evaporate, and the material will return to its original porous state and perform its original function. Furthermore, the porous 5iO1° bisque reacts chemically with the molten ash and adsorbs a large amount of it, so even if the chemical action of the high melting point compound added at the same time is the same, a much larger amount of molten ash will be absorbed. It becomes the benevolent that suppresses the hindrance of ash. After the test, 12
The adsorption amount of molten ash of porous sio, (silica gel) is 5~
ior, the adsorption amount of bisque 1f was 3 to 5f.

Experimental Example 2 A granular additive (3 to 5 mm in diameter) of MgC0 and CaCO5 was prepared using Funori, and 200 pieces of this were poured into the molten ash staying at the bottom of a heavy oil combustion furnace. As a result, the molten ash, which had been in a fluid state before being added, stopped moving9, and an increase in the melting point was observed even from outside the furnace. Just in case, put it in 4 i Qzl 7 ll + 1), EkFjhn ding ha Jj
J-441! As shown in Case 1 of the Ushidb't-a-ZL'R1 table, the effect of adding lye and water was observed.

A similar experiment was conducted using a different boiler. In this case, the high melting point compound is M, gO25wt% + A
l2O3S wt Chi, non-porous Sin! ! 50wt%.

Ca (OH), 20 wt% was used, and the effect of increasing the melting point was also observed in this case (see Case 2 in Table 1).
.

Experimental Example 3 The same one used in Experimental Example 1 was used, but high-melting point compounds with and without carbonate were prepared separately as shown below.

(1) Mixed carbonate MgCO, 50wt%, Mg(OH), 50wt%
.

51ot (porous) 20wt% (2) No carbonate Mg(OH) 280wt%, 5i02 (nonporous) 20
wt% The particle size of the additive is 1 to 3 WR.

The above additive was introduced toward the center of the molten ash in Example (1) in Table 1, and after the boiler was stopped, the distribution of the additive was investigated. After charging, additives containing carbonate rise after contact with molten ash,
It decomposes while producing carbon dioxide gas, but at the same time it becomes a fine powder and can be widely dispersed in the molten ash.

For example, MgCO3 is 540℃, CaCO3 is 898℃
, CaMg(C03)2 decomposes at 730-760°C.

After the boiler was stopped, we collected molten ash and investigated the distribution of additive components. As a result, the additive containing carbonate (1) was detected even from a location tsm away from the point of injection. On the other hand, in the case (2) in which no carbonate was added, the distribution of the components remained within 35 cm of the injection point.

Incidentally, similar effects were obtained using ￥CaCO3 as a carbonate, so not only M'gCO3 but also CaCO3 and the double salt Ca made of both of them can be used as a carbonate.
Mg(COs)t can also be used.

As detailed above, the present invention, in addition to conventional additives,
It is also characterized by the fact that porous materials are mixed in and the molten ash is physically adsorbed. therefore,
Materials that have this effect do not necessarily have to react with molten ash, but materials other than silica gel and unglazed ceramics can be used as long as they have the ability to withstand the temperature when they come into contact with molten ash. For example, various types of unglazed refractory bricks include Fe103, S102, and A1403.

ZrO2 etc. can be used.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a boiler in which the agent of the present invention is used. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (2)

[Claims] (1) Additives consisting of one or more of Mg compounds, Ca compounds, and Al compounds to funoori and casein. An agent for increasing the melting point of fuel ash, which is formed into a ball shape using gum arabic or a polymer binder and has a concentration of 1 c%. (2) Melting point of fuel ash characterized by forming an additive consisting of one or more of Mg compounds, Ca compounds, and Al compounds and a Si compound into a ball shape with funoori, casein, gum arabic, or a polymeric binding agent. elevating agent.