JPH0571284B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a flue gas treatment agent, and more particularly to a method for producing a flue gas treatment agent for flue gas generated from combustion of fuels such as coal and heavy oil and various wastes. [Prior art] Sulfur oxides, nitride oxides, chlorides, fluorides, etc. contained in the exhaust gas generated from the combustion of fuels such as coal and heavy oil and various wastes are harmful to buildings, structures, etc. In addition, it has been found that they have an extremely large effect on animals, plants, and even the human body, and methods for removing the above-mentioned substances from exhaust gas have been researched and a wide variety of methods have been developed. Among these methods, the so-called desulfurization and denitrification methods, which specifically remove sulfur oxides and nitrogen oxides, are broadly classified into dry methods and wet methods. Among the dry methods to which the present invention pertains, the methods shown in Table 1 are known.

【table】

[Problem that the invention seeks to solve]

The purpose of the present invention is to solve the various problems of the conventional dry desulfurization and denitrification methods described above, and to provide an easily molded flue gas that can simultaneously perform desulfurization and denitrification and also remove chlorides, fluorides, etc. An object of the present invention is to provide a method for producing a processing agent. [Means for Solving the Problems] The present invention provides a substance containing calcium oxide and/or calcium hydroxide, a sulfuric acid compound, a halogen element compound, a substance containing silicon dioxide, a substance containing aluminum oxide, and a substance containing calcium oxide and/or calcium hydroxide. thing,
and one or more substances selected from the group consisting of alkali metal hydroxides, mixed with water, subjected to humid air curing or steam curing, molded, and then humid air curing or steam curing again. This is a method for producing a flue gas treatment agent, which is characterized by heat treatment at a temperature of 0.degree. C. or higher. Examples of substances containing calcium oxide and/or calcium hydroxide of the present invention include by-products such as quicklime, slaked lime, cement, slag, dolomite plaster (containing lime), and acetylene slag. Sulfuric compounds and halogen element compounds are substances produced by combining alkaline earth metals such as calcium and magnesium, alkali metals such as sodium and potassium, and sulfuric acid and hydrogen halides, such as calcium sulfate and magnesium sulfate. , calcium chloride, magnesium chloride, sodium sulfate, potassium sulfate, calcium sulfite, calcium hydrogen sulfate, sodium chloride, strontium chloride, calcium bromide, calcium iodide,
Examples include potassium chloride, sodium thiosulfate, and black liquor combustion ash. Substances containing silicon dioxide include, for example, silicic acid, hydrous silicic acid, metasilicic acid, aluminum silicate, calcium silicate, cristobalite, tridymite, kaolin, bentonite, talc, perlite, shirasu, diatomaceous earth, glass, etc. Examples include compounds containing silicon. Examples of substances containing aluminum oxide include compounds containing reactive aluminum oxide, such as alumina, aluminum silicate, bentonite, kaolin, diatomaceous earth, zeolite, perlite, and bauxite. Examples of sulfides include calcium sulfide, iron sulfide, and zinc sulfide. Examples of the alkali metal hydroxide include sodium hydroxide and potassium hydroxide. Furthermore, when the required materials described so far are supplied by adding elemental sulfur, for example, the mutual reaction between the materials proceeds, resulting in the production of calcium sulfide, calcium sulfate, etc.
Furthermore, it also includes water glass produced by the reaction of silicic acid and caustic alkali. Examples of other substances that simultaneously contain two or more of the eight substances mentioned above include coal ash and coal fluidized bed combustion ash (sources of calcium oxide, silicon dioxide, aluminum oxide, calcium sulfate, sodium sulfate, potassium sulfate). , cement and cement clinker (calcium oxide, calcium sulfate,
silicon dioxide, aluminum oxide sources), slag and shirasu, andesite, chaat, quartz trachyte, opal, zeolite, feldspar, clay minerals, ettrin guides (sodium oxide, silicon dioxide, aluminum oxide, calcium oxide), etc. Examples include minerals containing silicon dioxide, sodium, aluminum, calcium, etc., chlorides, sulfates, etc., as well as in-furnace desulfurization ash such as fluidized bed combustion ash, and waste desulfurization agents after flue desulfurization. The present inventors have discovered the above eight types of substances (calcium oxide, calcium hydroxide, sulfuric acid compounds, halogen element compounds, silicon dioxide, aluminum oxide, sulfides, alkali metal hydroxides) (hereinafter these are abbreviated as base materials). The present invention was completed based on the discovery that various combinations of the following materials were combined, mixed with water and cured, and tested for flue gas treatment, and that depending on the combination and preparation method, unexpected performance was exhibited. The substance containing calcium oxide and/or calcium hydroxide may be an alkaline earth metal, a sulfuric acid compound of an alkali metal, or a halogen element compound, a substance containing silicon dioxide, a substance containing aluminum oxide, a sulfide, or a sulfuric acid compound of an alkali metal. Extremely excellent flue gas treatment performance can be obtained by combining hydroxides in the following formulation. The proportion of the base material is at least 1% as CaO, at least 0.1% as a sulfuric acid compound of an alkaline earth metal or alkali metal and/or a halogen element compound, as SiO ₂ 0-90% as Al ₂ O ₃ 0-70% as sulfide. At least 0.1% At least 0.1% as alkali metal hydroxide, preferably as CaO 1 to 80% As alkaline earth metal or alkali metal sulfuric acid compounds and/or halogen element compounds, preferably CaSO ₄ , Na ₂ SO ₄ , CaCl ₂ , NaCl
0.1-70% as SiO ₂ 5-90% as Al ₂ O 3 5-70% as Al 2 O ₃ Preferably calcium sulfide as sulfide 0.1-50% as alkali metal hydroxide
NaOH and/or KOH is 0.1-10%. The raw materials are mixed after being crushed if necessary, and water is further added and mixed. Water-soluble salts are dissolved in water before use. The amount of water added is per 100 parts of dry matter,
Preferably about 20 parts to about 80 parts, more preferably about 37 parts.
~70 copies. The resulting slurry or slurry mixture is then subjected to a first stage of wet air curing or steam curing. The conditions for moist air curing at this time are preferably a temperature of 10° C. to 40° C. and a relative humidity of 50% to 100% for several minutes to several tens of hours.
In addition, steam curing requires a temperature of 40°C to 180°C and a relative humidity of 100°C.
% for several minutes to 48 hours. This curing step is essential for molding the flue gas treatment material of the present invention after providing sufficient moisture necessary for the generation of active substances in the treatment agent to advance the flue gas treatment reaction. be. A slurry or muddy mixture is
By going through this step, the important initial stage of active compound formation necessary for flue gas treatment is completed, during which most of the water is consumed in the compound formation reaction, and the first stage of curing is completed. It is preferable to carry out this under conditions such that an appropriate moisture state is obtained for molding and granulating the mixture after curing. Next, the material that has undergone the first stage of curing is molded using a briquette machine or the like or molded (granulated) using a pelletizer or the like. Molding is performed easily and with a high yield because it goes through the steps described above. This molded product undergoes a second stage of curing and is sized to obtain the flue gas treatment agent of the present invention. The second stage of curing is 10℃ to 40℃ in moist air curing.
At a relative humidity of 50% to 100%, a period of about 1 day to 1 week is preferable, and for steam curing, a period of from 10 minutes to 72 hours at a temperature of 40° C. to 180° C. and a relative humidity of 100% is preferable. Furthermore, after curing, the molded product should be kept at a temperature above 30℃, preferably
The performance of the processing agent can be further improved by performing heat treatment in the range of 50°C to 200°C for 0.3 to 10 hours. The present invention will be described in more detail below with reference to Examples. Example 1 Commercially available slaked lime was mixed with coal ash, the chemical composition of which is shown in Table 2, and a solution of calcium chloride and water was mixed according to the formulation shown in Table 4, water was added, and the mixture was mixed again. do. Next, steam curing at 100°C under normal pressure was performed for 1 hour, and the obtained soft cured product was passed through a 5 mm sieve to prepare seeds for granulation, which was then granulated using a tube pelletizer, and again at 100°C under normal pressure. Steam curing is performed for 6 hours. The obtained granules are 1.7 mm ~
Sorted to 2.5 mm and as it is (undried product, Example 1)
-1) and 130°C for 2 hours to obtain a flue gas treatment agent of the present invention (Example 1-2). The performance test was conducted under the conditions shown in Table 3 (space velocity
A desulfurization and denitrification test (SO ₂ , NO _x removal test) was conducted at a gas temperature of 130°C (6000h ^-1 ). Note that the specific surface area was also measured. The specific surface area was measured by the BET method after degassing the sample at 200°C. These results are shown in Table 5.

【table】

[Table] Example 2 Coal ash was mixed with commercially available slaked lime, water was added to calcium chloride to dissolve it, the liquid was mixed at the ratio shown in Table 4, water was added and mixed again, and the mixture was heated at normal pressure at 100°C. After steam curing for 1 hour, the resulting soft cured product was passed through a 5 mm sieve to produce seeds for granulation.
Pelletize using a pan-type pelletizer and heat to 125℃ again.
High-pressure steam curing was performed for 3 hours, and the resulting granules were
The particles were sized to 1.7 to 2.5 mm and heat treated at 130°C for 2 hours to obtain the flue gas treatment agent of the present invention. The performance test was conducted under the same conditions as in Example 1, and the results are shown in Table 5. Example 3 Adding coal ash and calcium sulfate to commercially available slaked lime
Mix according to the formulation shown in the table, add water and mix. Hereinafter, in the same manner as in Example 1, flue gas desulfurization agents were obtained by the method of the present invention, unheated (Example 3-1) and heat treated (Example 3-2), and tested under the same conditions as in Example 1. The results shown in Table 5 were obtained. Example 4 Coal ash and calcium sulfate were added to commercially available slaked lime.
Add and mix in the proportions shown in the table, then add water to make the moisture content 42 parts per 100 parts by weight of raw material dry matter and mix again.
Next, steam curing at 100°C under normal pressure was performed for 1 hour, and the resulting soft cured product was passed through a 5 mm sieve to prepare seeds for granulation, granulated using a pan-type pelletizer, and again at 100°C under normal pressure. Steam curing is performed for 6 hours. The obtained granules are crushed and sized to 0.5 to 0.71 mm,
A heat treatment was performed at 130°C for 2 hours to obtain a flue gas treatment agent of the present invention. The performance test was conducted under the same conditions as in Example 1 except that the space velocity was 10,000 h ^-1 , and the results are shown in Table 5. Examples 5 to 14 Commercially available slaked lime and coal ash were contaminated with [MgSO ₄ ], [CaCl ₂ +S], and [CaCl _{2 +} ], respectively, as shown in Table 4.
FeS], [NaCl], [KCl], [Na ₂ SO ₄ ], [K ₂ SO ₄ ],
[S ₂ Cl ₂ ], [MgCl ₂ ], [CaSO ₄ + Na ₂ S ₂ O ₃ ]. In this case, if the raw materials other than slaked lime and coal ash are soluble in water, a portion of the amount of water used is After dissolving, slaked lime, and coal ash were mixed in powder, an aqueous solution thereof was added, and the remaining water used was added and mixed. Thereafter, granules were obtained in the same manner as in Example 4, and performance tests were conducted, with the results shown in Table 5 being obtained. Examples 15-16 Commercially available slaked lime, silicic acid, and aluminum hydroxide are mixed in the proportions shown in Table 4, and an aqueous calcium chloride solution is added and mixed again. Thereafter, a granulated product was obtained in the same manner as in Example 4, and a performance test was conducted, and the results shown in Table 5 were obtained. Example 17 Commercially available slaked lime and silicic acid are mixed, an aqueous calcium chloride solution is added, and the mixture is mixed again at the proportions shown in Table 4. Thereafter, a granulated product was obtained in the same manner as in Example 4, and a performance test was conducted, and the results shown in Table 5 were obtained. Example 18 Commercially available slaked lime and silicic acid are mixed in the proportions shown in Table 4, water is added, and the mixture is mixed again. Thereafter, a granulated product was obtained in the same manner as in Example 4, and a performance test was conducted, and the results shown in Table 5 were obtained. Example 19 Commercially available slaked lime and coal ash are mixed with sulfur in the proportions shown in Table 4, water is added, and the mixture is mixed again. Thereafter, a granulated product was obtained in the same manner as in Example 4, and a performance test was conducted, and the results shown in Table 5 were obtained. Example 20 Coal ash is added to commercially available slaked lime and mixed. A solution obtained by adding water to sodium hydroxide is mixed according to the formulation shown in Table 4, and water is added and mixed again. Thereafter, a granulated product was obtained in the same manner as in Example 4, and a performance test was conducted, and the results shown in Table 5 were obtained. Comparative example 1 100℃ after granulation with a pan-type pelletizer, 6
A preparation was prepared in the same manner as in Example 4, except that the atmospheric pressure steam curing was omitted, and the same performance tests as in Example 4 were conducted, and the results shown in Table 5 were obtained. Comparative Example 2 Coal ash is mixed with commercially available slaked lime, and a solution obtained by adding water to calcium chloride is mixed according to the formulation shown in Table 4, and water is added and mixed again. Next, we proceeded to the same granulation process as in Example 1 without performing the first stage of curing, but with a water content of 42%, the mixture was so soft that it was completely impossible to mechanically granulate and mold it. Ta. For this purpose, the performance test preparations were manufactured by rolling them one by one by hand. Next, steam curing at 100℃ for 6 hours at normal pressure, grading to 0.5 to 0.71mm, and heating at 130℃ for 2 hours.
A comparative sample was obtained by heat treatment for a period of time, and the same performance test as in Example 1 was conducted, and the results are shown in Table 5. Comparative Example 3 Coal ash is mixed with commercially available slaked lime, calcium sulfate is mixed according to the formulation shown in Table 4, and water is added and mixed again. Next, the same granulation process as in Example 1 was carried out without performing the first stage of curing, but the amount of water
At 42% the mixture is very soft and mechanically granulated;
It was completely impossible to mold it. For this purpose, the performance test preparations were manufactured by rolling them one by one by hand. Next, normal pressure steam curing was performed at 100℃ for 6 hours, and the temperature was 0.5~0.71.
Comparative samples were obtained by sizing them to a size of 1.5 mm and heat-treated at 130° C. for 2 hours, and the same performance tests as in Example 1 were conducted, and the results are shown in Table 5.

【table】

【table】

【table】

【table】

[Table] * Integral for 3 hours after test gas ventilation Removal rate Examples 21 to 23 The flue gas treatment agent obtained in Example 1-2 was crushed to 0.5
The grains were sized to ~0.71 mm, and 200 ppm of HCl was added to the simulated gas in Example 21 and in Example 22 as shown in Table 3.
100 ppm of HF and 500 ppm of SO ₃ were added in Example 23, respectively, and a removal test was conducted under the test conditions shown in the same table (space velocity: 10000 h ^-1 ). The results obtained are shown in the table below.

〔Effect of the invention〕

The flue gas treatment agent produced by the method of the present invention differs from conventional absorption and adsorption agents in that its raw materials contain a substance containing calcium oxide and/or calcium hydroxide, a sulfuric acid compound, a halogen element compound, and silicon dioxide. Coal ash, cement, slag, glass waste, fluidized bed combustion ash, In-furnace desulfurization ash, etc. can also be used,
Available raw materials are inexpensive and wide-ranging. Furthermore, the manufacturing process is relatively simple and the manufacturing equipment does not require particularly sophisticated equipment, so the production cost is advantageous compared to conventional products. In addition, by going through the steps of curing in the first stage → molding → curing in the second stage, which is a feature of the present invention, granulation can be carried out in a state where sufficient moisture is provided to generate the active substance in the treatment agent. It is possible to obtain a flue gas treatment agent that can be molded, is sufficiently cured, and has stable flue gas treatment performance. The flue gas treatment agent produced by the method of the present invention has high desulfurization and denitrification performance, and also shows excellent ability to remove HCl, HF, etc., so it can treat flue gas not only by burning fuel combustion flue gas but also by burning various wastes. can also be carried out effectively and can greatly contribute to pollution prevention. Further, as mentioned above, the raw materials used in the method of the present invention include coal ash, slag, gas slag, fluidized bed combustion ash,
Since waste such as in-furnace desulfurization ash can be utilized, it is also useful as a resource recycling technology.

Claims (1)

[Claims] 1. From the group consisting of substances containing calcium oxide and/or calcium hydroxide, sulfuric compounds, halogen element compounds, substances containing silicon dioxide, substances containing aluminum oxide, sulfides, and alkali metal hydroxides. It is characterized by mixing one or more selected substances with water, curing in humid air or steam, forming it, curing in humid air or steam again, and then heat-treating it as it is or at a temperature of 30°C or higher. A method for producing a flue gas treatment agent.