JPS6126552A - Cement raw material adhesion-preventive refractories - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a refractory material used for lining suspension preheaters in cement manufacturing plants.

<Prior art> In the element manufacturing plant, there is a part of the suspension preheater which is composed of a housing, a cycler, a duct, an auxiliary combustion furnace (calciner), etc. high alumina brick,
Chamots brick, high alumina electroformed brick, silicon carbide brick, spinel brick, maguro brick.

Lining refractories such as high alumina castable refractories, chamotte castable refractories, silicon carbide castable refractories, and chamotte plastic refractories have been used.

However, in the case of any of the above-mentioned refractory lining materials, the cement raw material adheres to the surface of the refractory material, which can eventually lead to clogging accidents such as cyclones. Conventionally, there was no effective and appropriate solution to this problem, so many people tried to remove it by pushing it down using a crowbar or by spraying high-pressure water. It was more difficult to rely on grueling work, and as a result, productivity declined and stable operation over a long period of time was hampered.

Although the causes of cement raw materials adhering to the refractory lining have not been fully investigated, in general, alkali chloride, alkali sulfate, calcium fluoride, alkali metals,
alkaline earth metal im double salt (2Ca SO, -K2
S 04>, calcium silicate, calcium aluminate, compound group containing iron, superlite (2CaO-8io
2.CaC0j), sulfate of pearlite (2(2Ca
0-8i O,) Ca 804) etc. and their combination J: to produce a low-temperature melting glass with a low eutectic point, in this case especially the influence of alkali metal or alkaline earth metal salts. For example, the lowest eutectic temperature of calcium sulfate, MS potassium, and potassium chloride is said to be 650°C, and the fluidity and stickiness of the glassy substance produced wets the surface of the refractory lining. It is believed that this wetting acts to bind the cement raw material to the surface of the refractory lining, and that this is how the cement raw material adhesion phenomenon occurs.

Therefore, by making the lining refractory material itself dense, the smoothness of the operating surface is improved, and adhesion due to entanglement of fibrous and flaky substances generated in and from cement raw materials is prevented. These countermeasures are powerless against adhesion caused by surface tension with the liquid phase, such as low-temperature melting glass produced from cement raw materials, and cannot be effective countermeasures. Additionally, with current technology, it is impossible to prevent low-temperature melting glass produced from cement raw materials from penetrating or penetrating by reducing the amount and diameter of pores distributed in the refractory material. However, there are limits to this, so the basolateral method cannot be an effective method. Another idea is to find a refractory raw material that will not produce sticky substances through the reaction between the low-temperature melting glass generated from cement raw materials and the refractory raw materials that make up the refractory material. Although it is possible to find a refractory raw material that reduces the amount of light to some extent, it is almost impossible to find a refractory raw material that does not completely react.

<Problems to be Solved by the Invention> An object of the present invention is to eliminate the drawback that the surface of the refractory lining is wetted by the low-temperature melting glass generated from the cement raw material, causing the cement raw material to adhere and grow.

<Means to solve the problem> As is well known, carbon/graphite materials have traditionally attracted attention only for their properties in the solid state, and they also have drawbacks in oxidation resistance, which has placed restrictions on their use. That's what I was receiving. However, the present inventors have newly focused on the gas and heat generated when carbon/graphite materials are oxidized, and the physical properties of the refractory material residue after oxidation, and examined the contribution to prevention of cement raw material adhesion. When I tried this, I surprisingly found that it worked extremely effectively.The present invention was completed based on this knowledge.

That is, the refractory material used for the lining of a part of the suspension heater of a cement manufacturing plant contains 20 to 90% by weight of a carbon/graphite material for generating oxidation gas from the inside of the refractory material through an oxidation reaction. This makes it possible to significantly improve the ability to prevent cement raw materials from adhering.

As the carbon/graphite material that is the oxidizing gas source, recarburizers and natural graphite can be used, and as binders, alumina cement and silicates can be used.

Known binders such as phosphates can be used.

The refractory material to which the carbon/graphite material and the binder are added may be any conventionally used refractory material, and the construction method may be a self-hardening monolithic refractory material such as pounding construction, pouring construction, In addition to spraying, vibration molding or press molding may be used as unfired bricks.

In the present invention, the content of carbon/R lead material is specified as 20-90% by weight, but the reason for this is that below 20% by weight,
The amount of gas produced by oxidation 2 The amount of reaction heat is too small, making the following effects insufficient, and the rate of decrease in strength of the refractory material remaining after oxidation is also small, making it impossible to peel off thinly. Moreover, if it exceeds 90% by weight, the oxidation rate will become abnormally fast and the life of the refractory material will be significantly shortened.

<Function> The gas generated when carbon and graphite materials are actively oxidized covers the surface of the refractory material and prevents cement raw materials from approaching and contacting the surface of the refractory material. Also, since the gas pressure inside the refractory material at that time is always kept higher than the atmospheric gas pressure in the furnace, it acts to prevent gaseous components such as alkali salts from entering the refractory material. Furthermore, the heat generated by oxidation keeps the temperature of the refractory material stable at a high temperature deep down, which causes the agglomeration level of alkali, etc., to migrate to the deep region.In this way, the surface of the refractory material is not wetted by alkali, etc. , it will be kept in a clean state to prevent secondary adhesion caused by adhesive force with cement raw materials.

The strength of the remaining refractory material after oxidation of the carbon/graphite material rapidly decreases, and the refractory material exhibits the effect of continuously peeling off in thin layers from the surface of the refractory material. This is also extremely effective in preventing the adhesion and growth of cement raw materials.

<Effects of the Invention> Although the oxygen concentration in the suspension preheater controlled to achieve the best thermal efficiency is approximately 2% or less and the temperature is in the range of 300-1100°C, the present invention The refractory material gently and continuously causes an oxidation reaction of the carbon/graphite material under such weak oxidation conditions, and generates and supplies oxidation product gas and oxidation reaction heat.

Due to the above-mentioned effects of the oxidation generated gas, the heat of the oxidation reaction, and the residual refractory material after oxidation, the phenomenon of cement adhesion growth is fundamentally improved, and it can be quickly removed using a crowbar or sprayed with high-pressure water. There is no need to go through the trouble of letting it drop and removing it. For this reason, although the present invention does not extend to those skilled in the art and has enormous benefits, it is by no means an exaggeration.
isn't it.

<Example> Example 1: A polygonal cylinder composed of a plurality of rectangular test specimens was installed in the gas path so that its axial direction was perpendicular. , 45° upward diagonal of the polygonal cylinder
A triple tube that can rotate at a rate of 10 revolutions per minute at an angle of It can be sprayed onto the inner surface.

A total of B11 types were prepared, including rectangular test samples 1i8a-'-d according to the present invention and e-11 conventional products as comparative examples not according to the present invention.

a. Using a recarburizing material as a carbon/graphite raw material, adding water to a mixture of the recarburizing material, silicon carbide, and aluminum dog cement, kneading, casting, and drying; b. Using the same recarburizing material, and adding water to the mixture; Add water to a mixture of carbonaceous material, silicate, and hardening agent, cross-wire cast, and dry! , : Item, C1 Same as carburizer, knead the carburizer, silicon carbide, and phosphate, and dry after rammer molding. d. Use natural graphite as the carbon/graphite raw material, and mix natural graphite and magnesia. Kneaded with phenolic resin, press-molded and dried, e. High alumina fired brick f, Spinel fired brick Q, Silicon carbide brick h, High alumina high strength dense castable refractory bar" (Group J The rainbow cement raw material was recovered from New Suspension Preheater, which actually manufactures Portland cement, and its chemical composition is shown in Table 1.

Table 1 Using the above test setup, the air ratio is 1.05 to 1.1.
2 kg/
The cement raw material was injected onto the test specimen at a rate of hr. The oxygen concentration at this time was 2% or less. Test piece surface temperature 1
The temperature was adjusted to 000 to 1100°C, and the experiment was conducted continuously for 60 hours.

2. Test results Table 2 shows the ratio of the cement raw material adhering area to the surface area of the test body in %.

From Table 2, it can be seen that there is a significant difference in the ability to prevent adhesion of cement raw materials between the products of the present invention and the comparative examples not according to the present invention. When observing the cross section of the specimen in the direction perpendicular to the operating surface, it was found that the black color caused by carbon and graphite had disappeared to a depth of 1 to 2 mm from the operating surface in all cases a to d, and the structure was slightly porous. In other parts, the black color indicating residual carbon and graphite remained completely. From this, it can be inferred that the oxidation rate of carbon and graphite was slow, and considering that even if carbon and graphite disappeared from the operational surface, almost no adhesion phenomenon of cement raw materials occurred. The oxidation gas and heat generated from inside the refractory material due to the oxidation reaction of carbon and graphite protect the working surfaces of the refractory material and the inside of the carbonized material, and prevent contact, adhesion, and penetration of cement raw materials, or even if they contact It is presumed that even if it adheres, it has the effect of causing it to peel off while still being slight, and in any case, it was confirmed that it is extremely effective in preventing cement raw materials from adhering.

Example 2: After constructing an insulating castable refractory material with a thickness of 5Qmm as a lining on the side wall of an actual The Suspension preheater,
A self-hardening monolithic refractory using carburized material, chamotte, and alumina cement was poured to a construction thickness of 230+11111. When the condition was observed after three months of use, there was very little adhesion of cement raw materials. Furthermore, when the deposit was rubbed by hand, it was easily peeled off. When the cut surface in the direction perpendicular to the operating surface was observed, the black color caused by the carburizer had disappeared to a depth of 5 mm from the operating surface.

Similar parts were constructed using conventional chamots castable refractories for comparison, and in the core part, adhesion of cement raw materials was observed from the beginning of use, and because the degree of adhesion was strong, high pressure was applied periodically. I had no choice but to spray water on it and peel it off.

Claims (1)

[Claims] 1. A refractory material used for the lining of a suspension preheater in a cement manufacturing plant, the refractory material containing carbon and carbon to generate oxidation gas from an oxidation reaction from inside the refractory material. A refractory material for preventing adhesion of cement raw materials, characterized by containing 20 to 90% by weight of graphite material. 2. The refractory material for preventing adhesion of cement raw materials according to claim 1, wherein the carbon/graphite material is artificial graphite or amorphous carbon. 3. The refractory material for preventing adhesion of cement raw materials according to claim 1, wherein the carbon/graphite material is natural graphite.