JP2009262047A - Method for utilizing waste material containing sludge in coal boiler for power generation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for utilizing a waste material which can efficiently use a large amount of a waste material, especially a waste material mainly comprising sludge, as fuel in a coal boiler for power generation, and at the same time promote effective utilization of coal ash generated from the coal boiler, and can reduce harmful nitrogen oxides generated from the coal boiler. <P>SOLUTION: The waste material containing sludge is partially oxidized with oxygen or oxygen enriched air in an entrained bed gasifier to be converted into combustible gas and slag. Coal and the combustible gas are burned by air in the coal boiler, and the coal ash is separated from the generated exhaust gas containing coal ash. The separated coal ash is added to the entrained bed gasifier, thereby transforming the coal ash into slag, and partially oxidizing unburned solid carbon remaining in the coal ash to transform it into combustible gas. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for effectively using activated sludge generated by biological treatment of sewage and industrial wastewater as fuel in a coal boiler for power generation.

  Woody biomass such as surplus activated sludge (hereinafter abbreviated as sludge) and timber (thinned wood, construction waste, residual lumber, etc.) generated when purifying wastewater, especially sewage by biological treatment, It is expected to be used effectively as a clean and recyclable carbonaceous resource that replaces fossil fuels. However, sludge and biomass have a high water content under normal conditions, and are solid-based fuels similar to coal, so they are poor in handling properties and have a high oxygen content. It is also a fact that it is an energy resource that is difficult to use, such as its calorific value is low compared to, and is currently treated as a kind of waste.

  As a means to effectively use sludge and woody biomass at low cost, direct fuel use is mainly used as fuel for coal boilers used mainly for power generation, and some practical examples have already been reported. Has been. However, since there are various differences between these waste materials and coal, such as basic properties (composition, ash melting point, etc.), combustibility, and handling properties, they must be mixed with coal and burned in a boiler. There was a limit to the rate at which

  In particular, sludge has a higher nitrogen content than coal or woody biomass, and when it is directly burned in a coal boiler, the amount of harmful nitrogen oxides generated accompanying combustion increases. There was also a problem of end.

  For example, Patent Document 1 discloses chlorine contained in waste fuel as one method for reducing quantitative restrictions in using waste fuel such as sludge and woody biomass in such a coal boiler. In order to reduce the burden on coal boilers due to toxic substances such as volatile compounds, waste fuel was gasified and converted to flammable gases, and toxic substances such as chlorinated compounds contained in the flammable gases were removed. Later, there has been proposed a method of using waste used as fuel for coal boilers.

JP-A-9-241666

  In Patent Document 1, waste that mainly cannot be thrown into a coal boiler for power generation is converted into a combustible gas by being treated as it is, and is contained in the combustible gas. It is said that corrosive chlorine compounds and heavy metal components are purified by washing with a venturi scrubber and then supplied as fuel to a coal boiler. However, in this method, the sensible heat of the combustible gas generated by gasifying the waste at a high temperature is not used at all, and the purpose of using the energy of the waste as much as possible effectively and efficiently. It was contrary to.

  On the other hand, coal ash (fly ash), which is generated in large quantities every day from coal boilers, is still being used effectively, although it is effectively used as a cement raw material (additive for clay substitutes), a concrete raw material, and a soil conditioner. In many cases, landfills are not landfilled, and there is a demand for the development of a wider range of effective utilization methods than ever before. In addition, even if coal ash is unavoidably finally landfilled, there is a risk of leaching of harmful metal substances (for example, As, Pb, Cr, etc.) contained in a small amount in the coal ash in the long-term span. Therefore, it is inevitable that these environmental considerations will become increasingly important in the future.

  As a means for solving various problems for effectively using the coal ash, it is extremely effective to melt the coal ash at a temperature equal to or higher than its melting point to form a slag. For example, by using slag, the conditions (granularity, strength, etc.) as a construction material (roadbed material) are satisfied, so that its application is expanded. Moreover, if it is a slag state, it will become possible to suppress the elution of the contained heavy metals which becomes a problem when using coal ash effectively by any method. Furthermore, even when landfill is unavoidable, the use of slag makes the bulk density much larger than that of coal ash, so it is meaningful for transportation to landfill and measures for extending the life of landfill. is there.

  However, it is of course possible to melt coal ash in a furnace such as an electric furnace or an arc furnace to make slag, but when comparing the costs (equipment cost, operation cost) for the effect, at present the coal ash is slag The reality is that it is economically difficult.

  Moreover, it is known that the coal ash contains at least 1% by mass or more, on average about 5 to 10% by mass, of unburned carbon that could not be combusted in the boiler. When coal ash is landfilled, these unburned carbon components are naturally discarded without being used for any energy. In addition, the carbon contained in the coal ash is a problem at present in making effective use of the coal ash. For example, when used as a cement raw material, stable operation in a cement kiln is hindered, and when mixed with concrete and used as a roadbed material, it causes a decrease in strength. Accordingly, if the carbon contained in the coal ash can be reduced or effectively used, it is extremely preferable from the viewpoint of effective use of the coal ash as well as the energy.

  Therefore, an object of the present invention is to use waste, particularly waste mainly composed of sludge, as a fuel in a large amount and efficiently in a coal boiler for power generation, and at the same time promote effective utilization of coal ash generated from the coal boiler, Is to provide a waste utilization method that can reduce harmful nitrogen oxides generated from coal boilers.

In order to achieve the above object, the gist of the present invention is as follows.
(1) In a spouted bed gasifier, waste containing sludge is partially oxidized with oxygen or oxygen-enriched air to convert it into combustible gas and slag, and the coal and the combustible gas are converted into air using a coal boiler. The coal ash is separated from the exhaust gas containing coal ash that is burned and generated, and the separated coal ash is input to the spouted bed gasification furnace to convert the coal ash into slag, and the coal A method for using waste containing sludge in a coal boiler for power generation, characterized in that the unburned solid carbon remaining in the ash is partially oxidized and converted into a combustible gas.
(2) The method for using waste containing sludge in a coal boiler for power generation according to (1), wherein the sludge is dried sludge dried by a sludge drying facility.
(3) The method for using waste containing sludge in a coal boiler for power generation according to (1) or (2), wherein the waste containing sludge contains woody biomass.
(4) The nitrogen oxide contained in the exhaust gas generated in the coal boiler is reacted with ammonia contained in the combustible gas generated by being converted in the spouted bed gasifier. The utilization method of the waste containing the sludge in the coal boiler for electric power generation of any one of (1)-(3) to do.
(5) In any one of (2) to (4), exhaust gas containing ammonia discharged from the sludge drying facility is introduced into the spouted bed gasifier or the coal boiler. The utilization method of the waste containing the sludge in the coal boiler for power generation as described.
(6) By mixing the ash in the waste containing the sludge and the ash in the coal ash in the spouted bed gasifier, the melting point of the ash after mixing is determined in the coal ash The method for using waste containing sludge in a coal boiler for power generation according to any one of (1) to (3), wherein the melting point is lower than the melting point of ash.

  According to the present invention, waste, particularly waste mainly composed of sludge is used as a fuel in a large amount and efficiently in a coal boiler for power generation, and at the same time, effective utilization of coal ash generated from the coal boiler is promoted. It is possible to reduce harmful nitrogen oxides generated from the boiler.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  FIG. 1 is an explanatory diagram showing a flow of a waste utilization method according to an embodiment of the present invention.

  In the present embodiment, an example is shown in which waste containing sludge and woody biomass is used, but the present invention can be implemented even with sludge alone.

  The spouted bed type gasification and melting furnace (hereinafter referred to as “entrained bed type gasification furnace”) described below is generally a gasification raw material that is pulverized to 10 mm or less using a gas such as nitrogen or air. The gasification raw material is put into the furnace by air current conveyance, and instantaneously reacts with oxygen (gasification reaction, partial oxidation reaction, incomplete combustion reaction) and oxygen introduced into the furnace at the same time as the gasification raw material. In general, the gasification furnace is defined as a type of gasification furnace that has a function of converting into gas within 20 sec) and simultaneously melting ash contained in the gasification raw material to form slag.

  The slag described here means one in which ash contained in sludge is melted at a temperature equal to or higher than its melting point (including one that has been cooled and solidified again). The melting point of ash means the melting point temperature defined in JIS (M8801 Ash Meltability Test Method).

  The coal boiler described below uses coal as an energy source, generates steam using the heat of combustion reaction, and uses the heat energy of the generated steam using a power generation facility (steam turbine and generator) 17. It is defined as a device that generates high-temperature and high-pressure steam in a steam power plant that converts it into electrical energy. There are various types of boilers, such as natural circulation boilers, forced circulation boilers, and once-through boilers, but supercritical pressure once-through boilers are mostly used as large-volume boilers for power generation in recent years. is there.

  Part of the sludge (so-called dehydrated cake) 1 discharged from the biological treatment facility of the sewage treatment plant is introduced into a sludge drying facility 2 such as a hot air dryer or a conduction heat transfer dryer, and subjected to a drying treatment. . At this time, it is desirable to reduce the moisture in the dried sludge after the drying treatment as much as possible in order to increase the thermal efficiency in the latter gasification melting furnace. However, if the drying of the sludge is advanced more than necessary, it will lead to an increase in the scale of the sludge drying equipment, an increase in the required fuel, etc. Therefore, the moisture content in the dried sludge makes it easy to pulverize the dried sludge. What is necessary is just to set it as the mass% or less.

The dried sludge 3 discharged from the sludge drying facility 2, the woody biomass 4 processed into fine powder (chips), and the coal ash 23 generated from the coal boiler 16 are spouted bed type gasified by air flow of nitrogen or air. Charged into the melting furnace 7. In the gasification melting furnace 7, the organic matter (unburned matter) mainly composed of carbon in the dry sludge 3 and the woody biomass 4 and the coal ash 23 is gasified from oxygen 5 or oxygen-enriched air. It is gasified at a high temperature of 1100 to 1700 ° C. by the partial oxidation reaction (incomplete combustion) used as an agent, and becomes a high-temperature combustible gas 15 (main components are H ₂ , CO, CH ₄ , CO ₂ , H ₂ O). And turn. At the same time, the ash in the dried sludge 3 and the woody biomass 4 and the ash in the coal ash 23 are melted and converted into slag. Most of the slag is extracted from the bottom of the gasification melting furnace 7 and recovered as product slag 11, but a part of it is scattered in the high-temperature combustible gas 15 discharged from the gasification melting furnace 7, It is desirable to prevent ash adhesion trouble (slagging) by blowing spray water or quench gas 12 in the gas cooler 8 at the upper part of the gasification melting furnace 7 and cooling it to 1000 ° C. or less, and solidifying the scattered molten slag. . At this time, if the gas cooling is performed more than necessary, the sensible heat of the gas cannot be effectively used in the coal boiler 16 at the subsequent stage, and the size of the gas cooler 8 is increased. It is not preferable. Therefore, the gas temperature at the outlet of the gas cooler 8 is desirably 800 to 1000 ° C.

  The high-temperature combustible gas 15 discharged from the gasification melting furnace 7 is put into a coal boiler 16 and burned by air 19 together with fuel coal 18 to be effectively used as boiler fuel. Unlike the case where the waste is supplied directly to the coal boiler 16 in the solid state as a fuel, the combustibility of these waste-derived fuels in the coal boiler 16 is changed by supplying the combustible gas to the coal itself. As a result, it becomes possible to use a large amount of waste as fuel in the coal boiler 16 without impeding the efficiency and operability of the original coal boiler 16. .

  At this time, the combustible gas 15 discharged from the gas cooler 8 is immediately put into the coal boiler 16, so that even the sensible heat of the combustible gas 15 is a steam production heat source (that is, a heat source for power generation) in the coal boiler 16. It can be used effectively. Of course, for this purpose, the combustible gas 15 must not contain a large amount of corrosive substances that may cause any damage to the coal boiler 16 side. In the present invention, it is desirable not to use waste such as waste plastic mainly composed of

  The exhaust gas 25 containing coal ash discharged from the coal boiler 16 is purified through a denitration facility 20, an air preheater 21, a dust removal facility 22 (electric dust collector), and a desulfurization facility 24, and then as a purified exhaust gas 26 from a chimney. Dissipated.

  All or a part of the coal ash 23 recovered in the dust removal equipment 22 is put into the gasification melting furnace 7, and the organic matter mainly composed of carbon contained in the coal ash 23 is converted into a combustible gas. At the same time, most of the ash content is slag.

Since the gasification reaction in the gasification melting furnace 7 is a reaction under a so-called reducing atmosphere, nitrogen contained in waste such as sludge 1 and woody biomass 4 (particularly nitrogen contained in a large amount in sludge). ) Is mostly converted to ammonia (NH ₃ ). In addition, the sludge 1 originally contains ammonia derived from ammonium ions (NH ⁴⁺ ) contained in a form dissolved in sewage, and these ammonia is released as a gas during drying and gasification. Accordingly, a considerable amount of ammonia is contained in the combustible gas 15 generated as a result of gasifying the waste gas containing the dried exhaust gas 27 and the sludge 1 generated when the sludge 1 is dried by the sludge drying facility 2. Become.

  Although different depending on the method of the sludge drying facility 2, the dry exhaust gas 27 is a component in which water vapor, ammonia, and odor components (such as methyl mercaptan) generated from the sludge are mixed in air such as hot air used in the drying process. Usually, dry exhaust gas requires a gas treatment facility for removing ammonia and odor components contained therein, but in the present invention, it is appropriate to use it as a part of combustion air in the coal boiler 16. The odor component contained in the dry exhaust gas 27 is burned and decomposed in the coal boiler 16.

Ammonia blown into the coal boiler 16 as part of the dry exhaust gas 27 and combustible gas is combined with nitrogen oxide (NO _x ) generated when the coal burns in the coal boiler 16 by the following reaction. It reacts and contributes to their detoxification and reduction. That is, in the present invention, nitrogen oxide contained in the exhaust gas produced in the coal boiler is reacted with ammonia contained in the combustible gas produced by conversion in the spouted bed gasifier, thereby producing nitrogen. Oxide can be reduced.
NO _X + NH ₃ + O ₂ → H ₂ O + N ₂

  In general, a denitration facility 20 for removing nitrogen oxides contained in the exhaust gas 25 is required after the coal boiler 16, but in the present invention, the effect of reducing nitrogen oxides by ammonia is reduced. Therefore, it is possible to reduce the scale of the denitration facility (or reduce the operating capacity of the denitration facility).

The melting point of various ash components is the content of basic components (Fe ₂ O ₃ , CaO, MgO, K ₂ O, Na ₂ O) and acidic components (SiO ₂ , Al ₂ O ₃ , TiO ₂ ) in the ash. It is known to be related to That is, the melting point is lowered by increasing the basic component, and conversely, the melting point is increased by increasing the acidic component. Therefore, the ratio of the basic component and the acidic component in the ash (defined below) , Referred to as “basicity”) as an index, it is a relative measure of the melting point.
Basicity = (Fe ₂ O ₃ + CaO + MgO + K ₂ O + Na ₂ O) / (SiO ₂ + Al ₂ O ₃ + TiO ₂ )
* The unit of ash composition is [mass%].

  The composition and properties of the coal ash 23 generated from the coal boiler 16 naturally vary depending on the type of coal, but in general, in order to avoid ash adhesion troubles in the coal boiler 16, coal typically used for boiler fuel applications As 18, there is a strong tendency to adopt coal (1300 ° C. or higher) having a relatively high melting point of ash. Similarly, the composition and properties of the ash contained in the sludge 1 and the woody biomass 4 are various, but the content of the basic component is larger than the ash in the coal 18 and the melting point is significantly low. The case is common.

  Therefore, the melting point of the ash formed by mixing the ash in each raw material (sludge, woody biomass, coal ash) blown in the gasification melting furnace 7 is the ash melting point of the coal ash 23 occupying most of the ash. Compared to this, there is a significant melting point drop. In addition, the gasification melting furnace 7 has a so-called reducing atmosphere condition filled with a reducing combustible gas. The coal ash 23 has a melting point of 50 ° C. or higher in the reducing atmosphere than in the oxidizing atmosphere. Is also known to decrease. Therefore, even when the temperature in the gasification melting furnace 7 is lower than the melting point of ordinary coal ash, the melting slag can be promoted, and the slag can be sufficiently formed for most coal ash. Thus, it is possible to achieve a significant energy saving as compared with the case where the coal ash 23 is made into slag by using an electric furnace alone. That is, in the present invention, the ash content in the waste containing sludge and the ash content in the coal ash are mixed in a spouted bed gasification furnace so that the melting point of the ash after mixing is reduced in the coal ash. By making it lower than the melting point of ash, melting slag can be promoted.

In particular, woody biomass contains a large amount of acidic components such as K ₂ O and Na ₂ O, and thus has a great effect on the melting point drop of coal ash. Therefore, it is desirable to use 20% by mass or more of the waste put into the gasification melting furnace 7 as woody biomass.

  The temperature in the gasification melting furnace 7 is such that the ash and coal ash 23 contained in the waste such as the sludge 1 and the woody biomass 4 are sufficiently melted and slagged, and stabilized from the bottom of the gasification melting furnace 7. The temperature is higher than the temperature at which the low viscosity state can be extracted, but if it is higher than necessary, the life of the furnace wall in the gasification melting furnace 7 is extremely shortened, and heat loss due to heat dissipation also increases. For this reason, the temperature is preferably 1600 ° C. or lower. More preferably, if it can be set to 1300 ° C. or lower, it is not necessary to use a special refractory (chromium refractory) or the like, which is preferable.

  The solid carbon contained in the coal ash 23 is a so-called unburned component (unburned material) that could not be burned in the coal boiler 16 by ordinary air combustion, and is extremely poor in reactivity with oxygen ( The gasification rate and the combustion rate are slow.) By using oxygen or oxygen-enriched air as a gasifying agent during gasification, the unburned solid carbon can be reacted. In order to convert carbon contained in such coal ash 23 into gas with high conversion efficiency, and also from the viewpoint of reducing sensible heat brought out by accompanying nitrogen, oxygen is preferable as the gasifying agent. Furthermore, it is more preferable to use oxygen as high as possible as the oxygen 5. However, the production of oxygen at a concentration higher than necessary only increases the demerits such as an increase in input energy in the oxygen production facility 10 and has little influence on the gasification itself. Therefore, the oxygen 5 used here is a general one. A concentration (80% by volume or more) that can be produced by an oxygen production method (adsorption separation method <PSA>, cryogenic separation method) may be used.

  In order to reduce the scale of the oxygen production facility 10, oxygen-enriched air obtained by mixing oxygen 5 produced from the air 9 by the oxygen production facility 10 with air may be used instead of oxygen. At this time, if the oxygen concentration in the oxygen-enriched air is higher than the oxygen concentration normally contained in the air, the efficiency of the gasification melting furnace 7 due to the sensible heat of the accompanying nitrogen is somewhat avoided. it can. However, in order to improve the thermal efficiency in the gasification melting furnace 7 and to convert the carbon in the coal ash 23 into gas with a little higher efficiency (carbon conversion rate), the gasifying agent is 80 volumes more than oxygen-enriched air. It is desirable to use at least% oxygen.

The amount of oxygen added here is an amount of oxygen smaller than the amount of oxygen (so-called theoretical oxygen amount) necessary for complete combustion of all organic matter in the sludge 1, woody biomass 4, and coal ash 23. The organic matter here means a portion (mainly carbon, hydrogen, nitrogen, sulfur, oxygen) from the ash content in the dry base sludge. The ratio varies depending on how much the calorific value in each raw material and the internal temperature of the gasification melting furnace 7 are set, but is a relative ratio (an index defined as an oxygen ratio) when the theoretical oxygen amount is 1. It is preferable to adjust within the range of 0.2-0.8. When the oxygen ratio is less than 0.2, the amount of organic matter that is converted into unburned material without being gasified becomes extremely large. When the oxygen ratio exceeds 0.8, combustible gas components (H ₂ , CH ₄ ) and the like, and most of them are converted to combustion gases (CO ₂ , H ₂ O), which is not preferable for the purpose of the present invention. More preferably, the adjustment is made within the range of 0.4 to 0.7. If gasification is performed within this range, the proportion of unburned matter generated with respect to the organic matter contained in the sludge is suppressed to 30% by mass or less, and the proportion of combustible components contained in the combustible gas is 40% by volume or more. (Based on dry gas).

  In addition, organic materials mainly composed of carbon in waste materials such as sludge 1 and woody biomass 4 and organic materials contained in coal ash 23 have greatly different gasification reaction rates, so gasification is performed from separate burners. It is desirable to put it into the melting furnace 7 and manage the oxygen ratio with each appropriate value. That is, the oxygen ratio of the burner 14 for coal ash whose gasification reaction rate is slower (difficult to gasify) than the oxygen ratio of the burner 13 for sludge 1 and woody biomass 4 having a fast gasification reaction rate (easy to gasify). It is desirable to raise it.

  Further, steam 6 may be used in combination with oxygen 5 as a gasifying agent. In particular, in the burner 14 for the coal ash 23 that is difficult to gasify, it is desirable to add the steam 6 as a gasifying agent together with the oxygen 5 in order to improve the carbon conversion rate.

  The pressure in the gasification melting furnace 7 is not particularly specified, but if the pressure is lower than the atmospheric pressure, there is a risk of explosion due to air leakage from the outside, which is not preferable. Further, when the pressurization condition is higher than the atmospheric pressure, there is an advantage that the gasification melting furnace 7 can be made compact.

  Wastes other than the sludge 1 thrown into the gasification melting furnace 7 are those that do not contain a large amount of corrosive substances such as chlorine, wood biomass, grass biomass, waste plastic, food residue, Any carbon material can be used as long as it can be introduced into the gasification melting furnace 7 by airflow conveyance. Further, instead of waste, coal (pulverized coal) may be used as a gasification raw material together with the sludge 1.

  In order to maximize the reduction effect of nitrogen oxides generated from coal boilers, it is better to use only sludge containing a lot of ammonia from the beginning as waste to be put into the gasification melting furnace. Other nitrogen other than ammonia contained in other wastes is also converted into ammonia during gasification, and the same effect as ammonia originally contained in the sludge is exhibited. Any sludge occupies 30% by mass or more of the waste put into the furnace (the sludge weight is based on the weight after the sludge dryer).

  As sludge 1 used in the present invention, in addition to sewage sludge, surplus activated sludge generated from biological wastewater treatment facilities (for example, coke oven wastewater (safe water) treatment equipment, stainless pickling wastewater treatment equipment, Excess sludge discharged from wastewater treatment facilities of various food factories) may be used.

  According to the flow shown in FIG.

  The analytical values of the sewage sludge 1, woody biomass 4 and coal ash 23 used are shown in Table 1, Table 2 and Table 3, respectively. In addition, this sewage sludge is what was discharged | emitted from the dehydrator of the sewage treatment plant (dehydrated cake).

  After drying sewage sludge 1 (dehydrated cake) 150 t / day in the sludge drying facility 2, the finely divided dried sludge 3 (32 t / day, moisture content 5.1 mass%) produced is also finely divided (chip-like) wood. The biomass 4 (50 t / day) together with the same burner 13 (two), and the coal ash 23 (50 t / day) generated from the coal boiler 16 from another burner 14 (two) by gas transportation by air. It was put into the chemical melting furnace 7.

In the gasification melting furnace 7, oxygen 5 (oxygen concentration 93%) produced in the oxygen production facility 10 was supplied to each burner as a gasifying agent (47500 Nm ³ / day). The oxygen ratio in the burner 13 for No. 4 was adjusted to 0.55, and the oxygen ratio in the burner 14 for coal ash was adjusted to 0.62. Moreover, steam 6 was supplied to the burner 14 for coal ash together with oxygen 5 as a gasifying agent (2 t / day).

  As a result of maintaining the temperature in the gasification melting furnace 7 at 1300 ° C., the organic matter in each raw material was converted into the combustible gas 15, and the furnace temperature was lower than the melting point of coal ash. However, the ash content in each raw material is mixed in the gasification melting furnace, and the melting slag is promoted by the melting point decrease due to the ash content of the dry sludge 3 and the woody biomass 4 and the melting point decrease due to the reducing gas atmosphere. It was able to collect as product slag 11 without. The generated high-temperature combustible gas is cooled to 1000 ° C. by water spray in the gas cooler 8 at the upper part of the gasification melting furnace, and then introduced into the coal boiler 16, which is effective as a fuel for generating electricity in the coal boiler 16. It was used for.

Moreover, the dry exhaust gas 27 discharged | emitted from the sludge drying equipment 2 was thrown into the coal boiler as a part of combustion air (not shown). The dry exhaust gas contains 1.2% by mass of ammonia, and the combustible gas contains 0.3% by mass (3000 ppm) of ammonia. The exhaust gas discharged from the coal boiler 16 due to the effect of introducing ammonia. concentration of NO _X in the became 130 ppm (denitration equipment 20 inlet). As a comparative example, only coal was also operated burned in a boiler, NO _X concentration in the exhaust gas is 200 ppm (also denitrification equipment 20 inlet) and, in the embodiment, the generation amount of significant nitrogen oxides in the exhaust gas It was possible to reduce.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

It is explanatory drawing which shows the flow of the utilization method of the waste which concerns on one Embodiment of this invention. It is explanatory drawing which shows the flow and mass balance of the utilization method of the waste in the Example of this invention.

Explanation of symbols

1 Sludge (dehydrated cake)
2 Sludge drying equipment 3 Dry sludge 4 Wood biomass 5 Oxygen 6 Steam 7 Gasification melting furnace 8 Gas cooler 9 Air 10 Oxygen production equipment 11 Product slag 12 Spray water or quench gas 13 Sludge or sludge and wood biomass burner 14 Coal ash Burner 15 Combustible gas 16 Coal boiler 17 Power generation equipment (steam turbine and generator)
18 Coal 19 Combustion air 20 Denitration equipment 21 Air preheater 22 Dedusting equipment 23 Coal ash 24 Desulfurization equipment 25 Exhaust gas 26 Purified exhaust gas 27 Dry exhaust gas

Claims (6)

In a spouted bed gasifier, waste containing sludge is partially oxidized with oxygen or oxygen-enriched air and converted into combustible gas and slag.
In a coal boiler, coal and the combustible gas are combusted by air, and the coal ash is separated from exhaust gas containing coal ash,
The separated coal ash is charged into the spouted bed gasifier and converted into slag, and the unburned solid carbon remaining in the coal ash is partially oxidized to be combustible. A method for using waste containing sludge in a coal boiler for power generation, characterized by being converted to gas.   The said sludge is the dry sludge dried with the sludge drying equipment, The utilization method of the waste containing the sludge in the coal boiler for electric power generation of Claim 1 characterized by the above-mentioned.   The waste containing a sludge in the coal boiler for power generation according to claim 1 or 2, wherein the waste containing the sludge contains woody biomass.   The nitrogen oxide contained in the exhaust gas generated in the coal boiler is reacted with ammonia contained in the combustible gas generated by conversion in the spouted bed gasifier. The utilization method of the waste containing the sludge in the coal boiler for electric power generation of any one of claim | item 1-3.   The coal for power generation according to any one of claims 2 to 4, wherein the exhaust gas containing ammonia discharged from the sludge drying facility is introduced into the spouted bed gasifier or the coal boiler. How to use waste containing sludge in boilers. By mixing the ash in the waste containing the sludge and the ash in the coal ash in the spouted bed gasification furnace, the melting point of the ash after mixing is reduced to the ash content in the coal ash. The utilization method of the waste containing the sludge in the coal boiler for electric power generation of any one of Claims 1-3 characterized by making it lower than melting | fusing point.

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