JP5121564B2 - Hazardous trace element elution inhibitor and method of inhibiting harmful trace element elution - Google Patents

Description

  The present invention relates to a harmful trace element elution inhibitor and a harmful trace element elution suppression method used for suppressing the elution of harmful trace elements from coal ash which is a fuel residue of coal.

  There are various methods for burning coal in a coal-fired power generation system. Among them, so-called pulverized coal combustion in which particles obtained by finely pulverizing coal are blown into a furnace and burned is mainly employed. A part of the coal ash, which is a residue after combustion, is used as civil engineering and building materials such as concrete and soil improvement materials from the viewpoint of effective use of resources, but the surplus is disposed of in landfills.

  By the way, coal used as fuel contains a trace amount of harmful elements such as boron, fluorine, selenium, arsenic and hexavalent chromium in addition to carbon. For this reason, in consideration of the environment, the allowable concentration of harmful trace elements from coal ash is regulated by law. However, there are over 100 coal types exported to Japan per year, and not all of them meet the above-mentioned regulatory values. For this reason, the technique for reducing the elution density | concentration of the harmful trace element contained in coal ash to below a regulation value is examined.

  For example, a method of adding a trace element elution inhibitor such as a chelating agent to coal ash and a method of solidifying coal ash with cement or the like are performed (see Patent Documents 1 to 3).

  Further, in Cited Document 4, in a coal thermal power generation system including a combustion boiler that burns coal, and a dust collector that is provided downstream of the combustion boiler and collects dust from the combustion residue of the coal, A method for improving the dust collection efficiency of the dust collector by adding combustion residue of the coal to the coal is disclosed. According to the invention described in the cited document 4, it is possible to increase the average particle size of the coal combustion residue as a result of physically taking in the fine mineral particles in which the coal combustion residue becomes fly ash.

JP 2003-164886 A JP 2003-200132 A JP 2002-194328 A JP 2007-333346 A

  However, the conventional techniques described in Patent Document 1 to Patent Document 3 reduce the elution concentration of harmful trace elements by adding an additive to coal ash which is a fuel residue. In this case, silos, water tanks, mixing equipment, etc. are required on a large scale as equipment for adding and mixing additives to coal ash, resulting in high processing costs and new equipment space. is there.

  Further, in the conventional techniques described in Patent Document 1 to Patent Document 3, although prevention of elution of heavy metals has been studied, studies on prevention of elution of light elements such as boron and fluorine have been insufficient.

  Furthermore, the method for improving the dust collection efficiency described in the cited document 4 is a method for improving the average particle diameter of the coal ash after combustion by adding coal ash to the coal before combustion. The composition of the harmful trace element elution inhibitor particularly suitable for suppressing the elution of harmful trace elements has not been studied at all.

  The present invention has been made in view of the above problems, and is a harmful trace element elution inhibitor used for suppressing the elution of harmful trace elements from coal ash by a simple method. It is an object of the present invention to provide a harmful trace element elution inhibitor particularly suitable for suppression, and a harmful trace element elution suppression method using the same.

  The present inventors have found that when the harmful trace element elution inhibitor contains coal ash and the calcium content is set to a predetermined amount or more, the above problems can be solved, and the present invention has been completed.

  Specifically, the present invention provides the following.

  (1) In a coal-fired power generation system, a harmful trace element elution inhibitor used to suppress the elution of harmful trace elements from coal ash, which is a combustion residue of the coal, when added to a furnace during the combustion of coal. A harmful trace element elution inhibitor containing coal ash obtained by burning coal and containing calcium in an amount of 5% by mass or more in terms of calcium oxide.

  The harmful trace element elution inhibitor (1) contains coal ash and contains 5 mass% or more of calcium in terms of calcium oxide. By adding a harmful trace element elution inhibitor containing coal ash to coal, the amount of ash in the combustion residue increases and the concentration of harmful trace elements in the combustion residue is reduced. It can be effectively suppressed.

  Moreover, in this invention, a harmful | toxic trace element elution inhibitor contains 5 mass% or more of calcium in conversion of calcium oxide. When such a toxic trace element elution inhibitor is mixed in coal, the toxic trace elements in the coal ash are physically separated by lowering the melting point of the coal ash that is the combustion residue and melting the surface of the coal ash particles. In addition to being able to be contained, the calcium component can be insolubilized by chemically reacting with some harmful trace elements.

  (2) The harmful trace element elution inhibitor according to (1), wherein the coal ash obtained by burning coal is coal ash containing 5 mass% or more of calcium in terms of calcium oxide.

  The harmful trace element elution inhibitor (2) contains coal ash rich in calcium. By adding such coal ash to the harmful trace element elution inhibitor, the calcium content of the harmful trace element elution inhibitor can be maintained at a preferable value.

  (3) The toxic trace element elution according to (2), wherein the coal ash containing 5% by mass or more of calcium in terms of calcium oxide is combustion ash of domestic coal, coal mountain coal, absaloca coal, or Bayeswater coal. Inhibitor.

  The harmful trace element elution inhibitor described in (3) specifies the type of coal that produces coal ash containing a large amount of calcium. By using such coal, the harmful trace element elution inhibitor of the present invention can be easily produced.

  (4) Furthermore, by adding at least one selected from the group consisting of slaked lime, quicklime, and limestone, calcium is contained in an amount of 5% by mass or more in terms of calcium oxide, as described in any one of (1) to (3). Harmful trace element elution inhibitor.

  The harmful trace element elution inhibitor described in (4) contains at least one selected from the group consisting of slaked lime, quicklime, and limestone in addition to coal ash. By adding these calcium sources to the harmful trace element elution inhibitor, the content of calcium in the harmful trace element elution inhibitor can be increased, and the effect of suppressing the harmful trace element elution by calcium can be enhanced.

  (5) Harmful trace element elution suppression that suppresses the elution of harmful trace elements from coal ash, which is the combustion residue of coal, by adding a harmful trace element elution inhibitor to coal, which is fuel in the coal-fired power generation system A harmful trace element elution suppression method comprising using the harmful trace element elution inhibitor according to any one of (1) to (4) as a harmful trace element elution inhibitor.

  The harmful trace element elution suppression method described in (5) defines the invention described in (1) to (4) as a method invention. Accordingly, the same effects as those of the inventions described in (1) to (4) can be obtained.

  (6) The harmful trace element elution suppression method according to claim 5, wherein the harmful trace element elution inhibitor is added so that the calcium contained in the coal ash after combustion is 4% by mass or more in terms of calcium oxide. .

  The harmful trace element elution suppression method described in (6) defines the addition amount of the harmful trace element elution inhibitor. Addition amount of harmful trace element elution inhibitor so that calcium contained in coal ash after combustion becomes 4% by mass or more in terms of calcium oxide, thereby transferring calcium to coal ash after combustion Can be sufficiently secured, and the effect of suppressing the elution of harmful trace elements can be sufficiently ensured.

  According to the present invention, since the harmful trace element elution inhibitor contains coal ash, the amount of ash in the fuel residue can be increased, and the amount of harmful trace element eluted can be reduced. In addition, since the harmful trace element elution inhibitor contains a predetermined amount or more of calcium, when mixed in coal, the harmful trace amount in coal ash is reduced by lowering the melting point of coal ash and melting the surface of coal ash particles. The element can be physically contained, and the calcium component can be insolubilized by chemically reacting with a part of the harmful trace element.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<A: Configuration of pulverized coal combustion facility in coal-fired power generation system>
Hereinafter, an embodiment showing an example of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a pulverized coal combustion facility 1 in a coal-fired power generation system. Here, as shown in FIG. 1, the pulverized coal combustion facility 1 includes a coal supply unit 12 that supplies coal, a pulverized coal generation unit 14 that converts the supplied coal into pulverized coal, and a pulverized coal that burns pulverized coal. The combustion part 16 and the coal ash process part 18 which processes the coal ash produced | generated by combustion of pulverized coal are provided. FIG. 2 is an enlarged view of the vicinity of the furnace 161 in the pulverized coal combustion unit 16.

<A-1: Coal supply section>
The coal supply unit 12 includes a coal bunker 121 that stores coal, and a coal feeder 122 that supplies the coal stored in the coal bunker 121. The coal bunker 121 stores coal to be supplied to the coal feeder 122. The coal feeder 122 continuously supplies the coal supplied from the coal bunker 121 to the coal pulverized coal machine 141. Moreover, this coal feeder 122 is provided with the apparatus which adjusts the supply_amount | feed_rate of coal, and, thereby, the amount of coal supplied to the coal pulverizer 141 is adjusted. Further, a coal gate is provided at the boundary between the coal bunker 121 and the coal feeder 122, thereby preventing air from the coal feeder from flowing into the coal bunker.

<A-2: Pulverized coal generation unit>
The pulverized coal generation unit 14 includes a coal pulverized coal machine (mill) 141 that converts coal into pulverized coal capable of pulverized coal combustion, and an air supply unit 142 that supplies air to the coal pulverized coal machine 141.

  The coal pulverized coal machine 141 pulverizes the coal supplied from the coal feeder 122 through the coal supply pipe to a fine particle size to form pulverized coal, and is supplied from the pulverized coal and the air supply unit 142. Mix with fresh air. Thus, by mixing pulverized coal and air, the pulverized coal is preheated and dried to facilitate combustion. Air is blown onto the formed pulverized coal, thereby supplying the pulverized coal to the pulverized coal combustion unit 16.

  Examples of the type of the coal pulverized coal machine 141 include a roller mill, a tube mill, a ball mill, a beater mill, an impeller mill, and the like. However, the type of the coal pulverized coal machine 141 is not limited to these and may be any mill used in pulverized coal combustion.

<A-3: Pulverized coal combustion section>
The pulverized coal combustion unit 16 includes a furnace 161 that combusts the pulverized coal generated by the pulverized coal generation unit 14, a heater 162 (heat exchange unit) that heats the furnace 161, and an air supply that supplies air to the furnace 161. Machine 163.

  The furnace 161 is heated by the heater 162 (heat exchange unit), and combusts the pulverized coal supplied from the coal pulverized coal machine 141 via the pulverized coal pipe together with the air supplied from the air supply unit 163. By burning pulverized coal, coal ash is generated and discharged to the coal ash treatment unit 18 together with the exhaust gas.

  The furnace 161 will be described in detail with reference to FIG. 2. In FIG. 2, the furnace 161 has a substantially inverted U shape as a whole, and after the combustion gas moves in an inverted U shape along the arrow in the figure. Then, it is reversed again into a U-shape, and the outlet of the furnace 161 (the last of the arrows in FIG. 2) is connected to the denitration device 181 and the dust collector 182 in FIG. In the pulverized coal combustion facility according to the present embodiment, the height of the furnace 161 is 30 m to 70 m, and the total length of the exhaust gas passage ranges from 300 m to 1000 m.

  Below the furnace 161, a burner 161a for burning pulverized coal is disposed in the vicinity of the burner zone 161a 'in the furnace 161. Further, near the top of the U-shape in the furnace 161, a furnace upper dividing wall 161b, a final superheater 161b ′, and a first reheater 161f (all of which are heat exchange units) are arranged, and further placed horizontally from there. A primary superheater 161c (heat exchange unit) is subsequently arranged. Further, a second reheater 161f ′ is provided in parallel with the horizontal primary superheater 161c, and from the vicinity of the terminal end of the horizontal primary superheater 161c, a primary economizer 161d (heat exchange unit). A secondary economizer 161e (heat exchange unit) is provided in two stages. Here, the economizer (also referred to as ECO) is a heat transfer surface group provided for preheating boiler feedwater using heat held by combustion gas. In the present embodiment, in the furnace 161, the primary economizer 161d and the secondary economizer 161e are separately installed in two stages, but the present invention is not limited to such a form. That is, the furnace 161 may have only a single economizer.

<A-4: Coal ash treatment unit>
The coal ash treatment unit 18 includes a denitration device 181 that removes nitrogen oxides in the exhaust gas discharged from the pulverized coal combustion unit 16, a dust collector 182 that removes soot in the exhaust gas, and coal ash collected by the dust collector 182. A coal ash recovery silo 183 for primary storage.

  The denitration device 181 removes nitrogen oxides in the exhaust gas. That is, ammonia gas is injected as a reducing agent into exhaust gas at a relatively high temperature (300 to 400 ° C.), and nitrogen oxides in the exhaust gas are decomposed into harmless nitrogen and water vapor by the action of a denitration catalyst, so-called dry ammonia contact A reduction method is preferably used.

  The dust collector 182 is a device that collects coal ash in the exhaust gas with an electrode. The coal ash collected by the dust collector 182 is conveyed to the coal ash collection silo 183. Further, the exhaust gas from which the coal ash has been removed is discharged from the chimney after passing through a desulfurization apparatus (not shown).

  The coal ash collection silo 183 is a facility that primarily stores the coal ash collected by the dust collector 182.

<B: Harmful trace element elution inhibitor of the present invention>
The harmful trace element elution inhibitor of the present invention is used in a coal-fired power generation system typified by the pulverized coal combustion facility 1, and is added to the furnace 161 at the time of coal combustion in the pulverized coal combustion facility 1. Therefore, it is a harmful trace element elution inhibitor used for suppressing elution of harmful trace elements from coal ash which is a combustion residue of the coal. The harmful trace element elution inhibitor of the present invention contains coal ash obtained by burning coal, and contains calcium in an amount of 5% by mass or more in terms of calcium oxide.

  By containing coal ash in the hazardous trace element elution inhibitor, the amount of ash in the combustion residue can be increased, so by reducing the content of harmful trace elements in the coal ash, elution of harmful trace elements Can be effectively suppressed. Moreover, since the harmful trace element elution inhibitor contains calcium in an amount of 5% by mass or more in terms of calcium oxide, the calcium content is transferred to the coal ash after combustion, and the melting point of the coal ash is lowered to melt the surface of the coal ash particles. Thus, harmful trace elements in coal ash can be physically contained, and the harmful trace elements can be insolubilized when the calcium component chemically reacts with some harmful trace elements.

  As coal ash used as a harmful trace element elution inhibitor, what contains 5 mass% or more of calcium in conversion of calcium oxide is preferable. By using coal ash having a calcium content of the above-mentioned content, it is possible to further enhance the harmful trace element elution suppression effect by the harmful trace element elution inhibitor.

  Although the manufacturing method of coal ash used for manufacture of harmful trace element elution inhibitor is not specifically limited, For example, it can manufacture by burning desired coal in the pulverized coal combustion facility 1 mentioned above. it can. The coal used for producing the coal ash added to the harmful trace element elution inhibitor of the present invention is not particularly limited, but includes domestic coal, coal mountain coal, absaloca coal, and Bayeswater coal. It is preferable to use it. Since the coal ash produced | generated from coal of these coal types contains many calcium content, the addition effect of the coal ash in a harmful | toxic trace element elution inhibitor can be improved more.

  The harmful trace element elution inhibitor of the present invention may contain at least one selected from the group consisting of slaked lime, quicklime, and limestone as other components. By adding these calcium sources to the harmful trace element elution inhibitor, the content of calcium in the harmful trace element elution inhibitor can be increased, and the effect of suppressing the harmful trace element elution by calcium can be enhanced.

  The harmful trace element elution inhibitor is preferably granular or powdery. Specifically, the average particle size is preferably 10 μm to 100 μm, more preferably 10 μm to 80 μm, and more preferably 10 μm to 60 μm. More preferably. When the average particle size is less than 10 μm, the average particle size is too fine and it is not practical as a harmful trace element elution inhibitor. When the average particle size exceeds 100 μm, the effect of adjusting the average particle size can hardly be obtained. Moreover, when making an average particle diameter into 80 micrometers or less, the particle size of a harmful | toxic trace element elution inhibitor can be adjusted using the coal pulverizer 141, and it is efficient. Furthermore, when the average particle size is 60 μm or less, the effect of adjusting the particle size of the harmful trace element elution inhibitor can be sufficiently obtained.

<C: Method for suppressing the elution of harmful trace elements of the present invention>
The harmful trace element elution suppression method of the present invention is a harmful effect that suppresses the elution of harmful trace elements from the combustion residue of coal by adding a harmful trace element elution inhibitor to coal as fuel in a coal-fired power generation system. Although it is a trace element elution suppression method, this is demonstrated using said pulverized coal combustion facility 1. FIG.

  This step includes a coal supply step S10 for supplying coal, a pulverized coal generation step S20 for pulverizing the supplied coal to generate pulverized coal, and a pulverized coal combustion step for generating coal ash by burning the pulverized coal. S30 and a coal ash treatment step S40 that collects and stores the coal ash, and each of these steps includes a coal supply unit 12, a pulverized coal generation unit 14, a pulverized powder of the above-described pulverized coal combustion facility 1, respectively. This is performed in the charcoal combustion unit 16 and the coal ash treatment unit 18. And harmful trace element elution inhibitor addition process S50 which is the characteristics of this invention is preferably performed in either of said coal supply process S10, pulverized coal production | generation process S20, and pulverized coal combustion process S30.

<Coal supply process S10>
First, in the coal supply process, the coal stored in the coal bunker 121 is supplied to the coal pulverized coal machine 141 by the coal feeder 122. The coal supplied to the coal pulverized coal machine 141 is specifically bituminous coal, subbituminous coal, lignite, or the like, but is not limited to these coals and can be pulverized coal combustion. Good.

<Pulverized coal production process S20>
Next, in the pulverized coal generation step, the coal supplied from the coal feeder 122 is pulverized by the coal pulverized coal machine 141, thereby generating pulverized coal. The generated pulverized coal is supplied to the furnace 161. At this time, the average particle size of the pulverized coal formed in the pulverized coal generation step may be a particle size range generally used in pulverized coal combustion, and generally 74 μm under 80 wt% or more. The degree of pulverization. This range can also be applied when a harmful trace element elution inhibitor is added.

<Pulverized coal combustion process S30>
Next, in the pulverized coal combustion process, the pulverized coal generated by the coal pulverized coal machine 141 is burned by the furnace 161. As shown in FIG. 2, the pulverized coal is burned in the burner zone 161a ′, and the temperature at this time ranges from 1300 ° C. to 1500 ° C., and the coal ash generated by the combustion rises in the direction of the arrow. And the exhaust gas through the furnace upper partition wall 161b, the final superheater 161b ', the first reheater 161f, the second reheater 161f', and the horizontal primary superheater 161c (all of which are heat exchange units). The primary economizer 161d (heat exchange unit) and the secondary economizer 161e (heat exchange unit) are sequentially passed. As described above, the vicinity of the heat exchange unit is an area where the temperature is maintained at about 850 ° C. to about 900 ° C., and heat transfer provided for preheating boiler feedwater using the heat held by the combustion gas. By passing through the plane group, heat is exchanged, and the temperature decreases. The time required for the exhaust gas to reach from the burner zone 161a ′ to the vicinity of the economizer is approximately 5 to 10 seconds. Then, it is sent to a denitration device 181 and a dust collector 182 at the subsequent stage. The coal ash produced in this pulverized coal combustion process is usually in the form of a powder having an average particle size in the range of 1 μm to 100 μm.

<Coal ash treatment process S40>
Thereafter, the coal ash generated by burning pulverized coal is discharged to the denitration device 181 together with the exhaust gas, and sent to the coal ash recovery silo 183 through the dust collector 182. The dust collector 182 is preferably provided in a plurality of stages.

<Harmful trace element elution inhibitor addition step S50>
As shown in FIG. 1, the harmful trace element elution inhibitor addition step S50, which is a process of adding the harmful trace element elution inhibitor, which is a feature of the present invention, is preferably the coal supply step S10 and the pulverized coal generation step S20 described above. The pulverized coal combustion step S30 is performed (S51, S52, S53 in FIG. 1 respectively).

  In addition, the addition place of a harmful | toxic trace element elution inhibitor will not be specifically limited if it is a state of coal, For example, the transfer path between coal supply process S10 and pulverized coal production | generation process S20, pulverized coal production | generation process S20, It may be performed in a transfer path between the pulverized coal combustion step S30 and the like.

  Specifically, for example, a method of supplying and mixing a harmful trace element elution inhibitor on a belt conveyor that is being transferred when transporting from the coal feeder 122 to the coal pulverizer 141, a harmful trace element elution inhibitor, A method of directly feeding into a coal hopper (not shown) of the coal pulverized coal machine 141, a method of supplying an agent charging port in a pipe between the coal pulverized coal machine 141 and the furnace 161, and directly to the furnace 161 together with combustion air A method of charging, a furnace upper dividing wall 161b, a final superheater 161b ′, a first reheater 161f, a second reheater 161f ′, a horizontal primary superheater 161c, which constitute a part of the furnace 161; However, the method is not limited to these. As described above, the method of the present invention does not require a new facility, and can be applied by a slight improvement of the existing facility. Therefore, the existing facility can be used effectively, which is advantageous in terms of cost.

  It is preferable to add the harmful trace element elution inhibitor to the coal so that the calcium contained in the coal ash after combustion is 4% by mass or more in terms of calcium oxide. When the calcium content in the coal ash after combustion is less than 4% by mass in terms of calcium oxide, the effect of adding a harmful trace element elution inhibitor cannot be substantially obtained. On the other hand, the harmful trace element elution inhibitor is preferably less than 10% by mass from the viewpoint of preventing slugging and fouling associated with the addition of calcium. The preferable value of the calcium content in the coal ash after combustion is 5% by mass.

  The harmful trace element elution inhibitor is preferably added so that the melting point of coal ash produced as a result of combustion is 1200 ° C. or higher, and more preferably 1300 ° C. or higher. Since the melting point of coal ash is 1200 ° C. or higher, it is possible to prevent the coal ash from being excessively melted inside the furnace 161 and causing slagging and fouling. Furthermore, by adding so that the melting point of coal ash becomes 1300 ° C. or higher, the effect of preventing the occurrence of such slugging and fouling can be obtained more strongly.

  The melting point of coal ash is greatly affected by the components of coal ash. That is, when there is a large amount of iron (III) oxide, calcium oxide, magnesium oxide, sodium oxide, potassium oxide, etc. in the coal ash, the melting point of the coal ash tends to be relatively low, When a large amount of silicon oxide, aluminum oxide, titanium oxide or the like is present, the melting point of coal ash tends to be relatively high. When adding the harmful trace element elution inhibitor, the melting point of coal ash can be adjusted by adjusting the content of these components in the coal ash.

Moreover, in this invention, adding the elution inhibitor for coal addition so that pH of the aqueous solution produced | generated by adding 10 mass parts of coal ash with respect to 100 mass parts of water may become 12.0 or more. You can also. Elements such as selenium, boron, and arsenic have a property that the higher the pH of coal ash, the more difficult it is to elute from coal ash. For this reason, it can suppress effectively that these elements elute from coal ash by making pH of coal ash 12.0 or more.
The limestone is preferably added so that the pH of the aqueous solution adjusted under the above conditions is 12.5 or more, and more preferably 13.0 or more. By adding limestone to such a pH, it is possible to further enhance the elution suppressing action of elements such as selenium, boron and arsenic.

  11.4 parts by mass of coal ash was added to 100 parts by mass of Senakin coal, which is Indonesian bituminous coal, and this mixed coal was pulverized by a mill. The calcium content in the added coal ash was 3.5% by mass in terms of calcium oxide. This mixed coal was supplied to a pulverized coal combustion facility and burned. Coal ash, which is a combustion residue, was collected from the horizontal portion and an electric dust collector (EP).

The concentration of harmful trace elements eluted from the collected coal ash was measured by the method described in Ministry of the Environment Notification No. 46 (1991). In this test, 500 ml of distilled water was mixed with 50 g of coal ash to prepare a sample solution, and the prepared sample solution was shaken continuously for 6 hours using a shaker at normal temperature and pressure, and then a membrane having a pore diameter of 0.45 μm. It filtered with the filter and was set as the test solution. The results are shown in Table 1.

  From Table 1, when coal ash is added, it turns out that the elution amount from the coal ash of boron, trivalent chromium, and hexavalent chromium has decreased significantly. From these results, it was found that by using a harmful trace element elution inhibitor containing coal ash, the elution of harmful trace elements from coal ash, which is a combustion residue, can be suppressed.

It is a schematic block diagram of the pulverized coal combustion facility in the coal thermal power generation system which shows one Embodiment of this invention. It is an enlarged view of the vicinity of the furnace in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pulverized coal combustion facility 12 Coal supply part 121 Coal bunker 122 Coal feeder 14 Pulverized coal production | generation part 141 Coal pulverized coal machine 142 Air supply machine 16 Pulverized coal combustion part 161 Furnace 162 Heating machine 163 Air supply machine 18 Coal ash processing part 181 Denitration equipment 182 Dust collector 183 Coal ash recovery silo S10 Coal supply process S20 Pulverized coal generation process S30 Pulverized coal combustion process S40 Coal ash treatment process S50 Hazardous trace element elution inhibitor addition process

Claims (4)

This is a harmful trace element elution suppression method that suppresses the elution of harmful trace elements from coal ash, which is the combustion residue of coal, by adding a harmful trace element elution inhibitor to coal that is fuel in a coal-fired power generation system. And
As the harmful trace element elution inhibitor , containing coal ash obtained by burning coal , using a harmful trace element elution inhibitor containing 5 mass% or more of calcium in terms of calcium oxide ,
The harmful trace element elution inhibitor is added so that the calcium contained in the coal ash after combustion is 4% by mass or more and less than 10% by mass in terms of calcium oxide. . The harmful coal as defined in claim 1, wherein the coal ash obtained by burning coal uses a harmful trace element elution inhibitor which is coal ash containing 5 mass% or more of calcium in terms of calcium oxide. Trace element elution suppression method. The coal ash containing 5% by mass or more of calcium in terms of calcium oxide is characterized by using a harmful trace element elution inhibitor that is combustion ash of domestic coal, coal mountain charcoal, absaloca charcoal, or Bayeswater charcoal. The method for suppressing elution of harmful trace elements according to claim 2. Furthermore, by using at least one selected from the group consisting of slaked lime, quick lime, and limestone, a harmful trace element elution inhibitor containing 5 mass% or more of calcium in terms of calcium oxide is used. The harmful trace element elution suppression method according to any one of 1 to 3.

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