JP2021146285A - Alkaline metal removal device and method - Google Patents

Abstract

To provide an alkaline metal removal device and method for efficiently removing alkaline metal from biomass ash and effectively utilizing the alkaline metal as a cement raw material or the like.SOLUTION: An alkaline metal removal device comprises: a preheater preheating biomass ash fed from a burning ash supply apparatus; a waste supply apparatus supplying chlorine-containing waste; a heater for forming alkaline metal chloride by heating together the preheated biomass ash and the supplied chlorine-containing waste; a flushing apparatus making the chloride-forming alkaline metals elute in a flushing liquid by flushing heat-treated materials of biomass ash and chlorine-containing waste generated in the heater; a solid-liquid separation apparatus collecting a cake of the heat-treated materials by performing the solid-liquid separation of the slurry discharged from the flushing apparatus; and a combustion furnace burning a combustion gas from the heater and supplying the exhaust gas after burning to the preheater.SELECTED DRAWING: Figure 1

Description

The present invention provides an alkali metal removing device for removing alkali metals from the combustion ash of woody biomass using chlorine-containing waste such as waste plastic in order to effectively utilize the combustion ash of woody biomass as a raw material for cement. The present invention relates to a method for removing alkali metal from combustion ash of woody biomass using the device.

For woody biomass such as tree trunks and branches, cutting chips, ash powder, bark, wood pellets, PKS (palm kernel shell), and construction waste, in parallel with technological development using fuel for power generation boilers, woody Development is also underway on a technique for effectively utilizing flying ash of combustion ash (hereinafter sometimes referred to as "biomass ash") generated by combustion of biomass.

Biomass ash is characterized by having a high content of alkali metals, particularly potassium, as compared with, for example, coal ash and waste combustion ash. Therefore, for example, when applying the cement raw material technology that enables effective utilization of a large amount of coal ash and waste combustion ash to biomass ash, the cement uses alkali metal components as repellent components, so that the biomass ash becomes alkaline. It is necessary to remove the metal. Furthermore, if alkali metals can be removed from the flying ash of woody biomass ash, it will be possible to develop applications for using flying ash of woody biomass ash as a concrete admixture or cement mixture, as is the case with coal ash (fly ash). Become.

As a technique for removing an alkali metal component from biomass ash, for example, in Patent Document 1 below, biomass ash collected by a bag filter is classified at a predetermined classification point, and fine powder combustion ash having a high potassium concentration is separated. A combustion apparatus and a method for treating combustion ash to be recovered are disclosed.

Japanese Unexamined Patent Publication No. 2017-122550

However, as described in Patent Document 1, the content of potassium contained in biomass ash and the particle size of biomass ash having a high potassium concentration vary depending on the type of woody biomass, the type of boiler used, the operation method, and the like. Therefore, in the method of Patent Document 1, it is necessary to adjust the classification point each time based on the properties of the woody biomass fuel and the like, and there is still room for improvement.

Therefore, an object of the present invention is to provide an alkali metal removing device and an alkali metal removing method using the device for efficiently removing an alkali metal from biomass ash and effectively using it as a raw material for cement or the like. ..

The alkali metal removing device of the present invention is a device for removing alkali metal from biomass ash, and is a combustion ash supply device for supplying the biomass ash and the biomass ash supplied from the combustion ash supply device. A preheating device for preheating, a waste supply device for supplying solid chlorine-containing waste, a preheated biomass ash supplied from the preheating device, and a solid supplied from the waste supply device. The heating device for heating the chlorine-containing waste in the shape together to form an alkali metal chloride, and the heat-treated product of the biomass ash and chlorine-containing waste generated by the heating device are washed with water. A water washing device for eluting the alkali metal forming chloride into a water washing solution, a solid-liquid separating device for solid-liquid separating the slurry discharged from the water washing device, and recovering the cake of the heat-treated product. It is characterized by including a combustion furnace for burning the combustion gas from the heating device and supplying the exhaust gas after combustion to the preheating device.

That is, in the alkali metal removing device of the present invention, the biomass ash and the chlorine-containing waste are heated together in the heating device and then washed with water, so that the alkali metal chloride is roasted using chlorine in the chlorine-containing waste. The alkali metal of the biomass ash that has become can be effectively dissolved and removed in the washing liquid, and the tar, carbon monoxide, dioxin, etc. derived from chlorine-containing waste generated in the heat treatment can be removed in the combustion furnace. It can be burned to make it harmless. Then, by utilizing the apparent heat of the exhaust gas for preheating the biomass ash in the preheating device, the temperature of the biomass ash sent to the heating device can be raised, so that the temperature is suitable for the reaction in which the alkali metal becomes chloride. By being able to form the state in almost all of the heating device, the alkali metal can be effectively removed from the biomass ash.

Further, the alkali metal removing device of the present invention is for solid-gas separation of the gas treatment agent spraying device for spraying the gas treatment agent on the exhaust gas from the preheating device and the exhaust gas to which the gas treatment agent is sprayed. It is characterized by being provided with a solid air separating device.

Therefore, the alkali metal removing device of the present invention can detoxify the hydrogen chloride gas in the exhaust gas, and the chlorine component in the recovered hydrogen chloride gas can be used as a chlorine source for removing the alkali metal.

Further, the alkali metal removing device of the present invention is characterized in that the heating device is a rotary kiln.

Therefore, since the biomass ash and the chlorine-containing waste in the heating device are well mixed and heated uniformly, the alkali metal removing device of the present invention efficiently and continuously removes the alkali metal from the biomass ash. It is possible to do it. Here, the combustion method of the rotary kiln is not limited, and it may be an internal combustion type or an external heat type.

Further, the alkali metal removing device of the present invention is characterized in that the preheating device is a cyclone.

Therefore, the alkali metal removing device of the present invention can effectively utilize the waste heat from the rotary kiln and the combustion furnace as a heat source for preheating biomass ash. The radix of the cyclones constituting the preheating device is not limited, and may be a one-stage type or a multi-stage type.

Further, in the alkali metal removing device of the present invention, the combustion furnace is characterized in that it uses any of pulverized coal, natural gas or kerosene as fuel.

By using pulverized coal, natural gas, or kerosene as the fuel for the combustion furnace, tar, carbon monoxide, and dioxins contained in the exhaust gas from the preheating device are burned and rendered harmless without regenerating dioxins. Can be done.

Further, in the alkali metal removing device of the present invention, the gas treatment agent is slaked lime.

By using slaked lime as the gas treatment agent, chlorine in hydrogen chloride gas contained in the exhaust gas from the preheating device can be detoxified as calcium chloride and separated and recovered.

Further, the alkali metal removing method of the present invention is a method for removing an alkali metal from biomass ash, in which a preheat treatment step for preheating the biomass ash and the preheated biomass ash and chlorine-containing waste are combined together. It is characterized by comprising a heat treatment step of heating and a water washing treatment step of dissolving an alkali metal chloride contained in the heat-treated product obtained in the heat treatment step in water.

According to this, by providing a preheat treatment step and preheating the biomass ash, the alkali metal chloride generated in the heat treatment step is rapidly generated, so that the alkali metal chloride derived from the alkali metal in the biomass ash is used. Since it can be obtained efficiently, the amount of alkali metal in the biomass ash finally removed in the water washing treatment step can be increased.

Further, in the alkali metal removing method of the present invention, the preheat treatment step is a step of preheating the biomass ash to a temperature of 400 ° C. or higher.

According to this, it becomes easy to quickly stabilize the temperature of the biomass ash in the heat treatment step in the temperature range of 650 ° C. to 1000 ° C. where the formation reaction of the alkali metal chloride occurs, and the chloride in the alkali metal in the biomass ash becomes easy. It is possible to easily obtain a state in which roasting is stably generated. When this preheating temperature is less than 400 ° C., the time during which the temperature of the biomass ash in the heat treatment step is in the temperature range in which the chloride roasting reaction occurs is shortened, and the degree of temperature rise in the heat treatment step is increased, so that the biomass Instability occurs in the temperature control of ash, and the reaction of chlorination roasting becomes unstable.

Further, the alkali metal removing method of the present invention is characterized in that the chlorine-containing waste is polyvinyl chloride.

As a result, wastes and the like, which have a high chlorine content and are poorly used for recycling, can be effectively utilized.

Further, the alkali metal removing method of the present invention is characterized in that the size of the biomass ash is 5 mm or less.

If the size of the biomass ash is larger than 5 mm, the efficiency of the dealkali reaction in the heat treatment step may decrease. The size of the biomass ash is the size of the opening of the sieve, and the size of 5 mm or less means that the biomass ash passes through the sieve having a opening of 5 mm.

Further, the alkali metal removing method of the present invention is characterized in that the size of the chlorine-containing waste is 80 mm or less.

When the size of the chlorine-containing waste is larger than 80 mm, the entire chlorine-containing waste cannot be heated to a predetermined temperature in the heat treatment step, and a large amount of chlorine is contained in the combustion residue of the chlorine-containing waste. May remain. The size of the chlorine-containing waste is the size of the opening of the sieve, and the size of 80 mm or less means that the waste passes through the sieve having an opening of 80 mm.

As described above, according to the present invention, it is possible to provide an alkali metal removing device and an alkali metal removing method for efficiently removing alkali metals from biomass ash, and the biomass ash is effectively used as a cement raw material or the like. Will be possible.

It is an overall block diagram which shows one Embodiment of the alkali metal removing apparatus which concerns on this invention. It is a flow chart which shows the procedure of the alkali metal removal method in embodiment shown in FIG.

Biomass ash present invention is applied, an alkali metal (Na, K) chloride, carbonate, sulfate, containing a silicate glass, _{R 2} O terms _{(R 2 O = Na 2 O} + 0.658 × contains about 3 wt% to 50 wt% in K ₂ O).

According to the alkali metal removal process of the present invention, reducing the concentration of the alkali metal component contained in the biomass ash, 2.0% by weight or less in the R _{2 O} terms, to a 1.5% by mass or less and more typically Therefore, it becomes possible to effectively use the biomass ash as a raw material for cement and the like. The concentration of the alkali metal in the biomass ash can be measured by a well-known method, and for example, a method based on JIS R 5204 "Fluorescent X-ray analysis method of cement" is preferably exemplified.

Hereinafter, the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to the aspects described with these drawings.

FIG. 1 shows an overall configuration diagram showing an embodiment of the alkali metal removing device according to the present invention. In FIG. 1, the flow of solids such as biomass ash is indicated by a solid line with an arrow, and the flow of air or exhaust gas is indicated by a broken line with an arrow.

The alkali metal removing device 1 according to this embodiment includes a combustion ash supply device 2 for supplying the biomass ash BA1, a preheating device 3 for preheating the biomass ash BA1 supplied from the combustion ash supply device 2, and a chlorine-containing waste. Waste supply device 4 for supplying the product PL to the heating device 5, heating device 5 for heating the preheated biomass ash BA2 and chlorine-containing waste PL at the same time, biomass ash BA2 and chlorine content discharged from the heating device 5 A water washing device 6 for washing the heat-treated product BA3, which is a mixture of combustion residues of waste PL, and a cake BA4 containing the heat-treated product BA3 after solid-liquid separation of the slurry S1 discharged from the water washing device 6 Gas treatment agent for the solid-liquid separation device 7 for recovering the A gas treatment agent spraying device 9 for spraying the biomass, and a solid air separation device 10 for separating and recovering the chlorine component P1 in the exhaust gas G4 from the gas treatment agent spraying device 9 and then transporting the chlorine component P1 to the waste supply device 4. ..

The combustion ash supply device 2 is provided to supply the received biomass ash BA1 to the preheating device 3. The combustion ash supply device 2 may be provided with a storage tank for the received biomass ash BA1. Further, the combustion ash supply device 2 may be provided with a storage place for drying the biomass ash BA1 and a drying device, and further, a crushing device for crushing the large-diameter biomass ash BA1 is attached. You may. These drying devices and the like may be appropriately used depending on the state of the received biomass ash BA1.

The combustion ash supply device 2 is not particularly limited as long as it can quantitatively discharge the biomass ash BA1, and a loss-in weight type hopper, a hopper provided with a quantitative feeder or a rotary feeder, or the like can be preferably used.

The preheating device 3 is provided for preheating the biomass ash BA1. The preheating device 3 shown in FIG. 1 is a multi-stage cyclone type preheating device composed of two cyclones, a cyclone 3a and a cyclone 3b. In this preheating device 3, the biomass ash BA1 supplied from the combustion ash supply device 2 to the upper cyclone 3a rises from below when it descends toward the lower cyclone 3b and further to the heating device 5 due to gravity. Heat is exchanged with the high-temperature exhaust gas G2 in each cyclone to preheat it, and it becomes biomass ash BA2 having a temperature of 550 ° C to 750 ° C and is sent to the heating device 5.

The waste supply device 4 is provided to supply the received chlorine-containing waste PL to the heating device 5. The waste supply device 4 may be provided with a storage tank for the received chlorine-containing waste PL. Further, a classification device for removing coarse matter from the received chlorine-containing waste PL and a crushing classification device for making the coarse matter into a predetermined particle size may be attached to the upstream side of the storage tank. These classifying devices and crushing classifying devices may be appropriately used depending on the state of the received chlorine-containing waste PL.

The waste supply device 4 is provided with a discharge amount adjustment device such as a discharge amount adjustment valve so that the supply amount of chlorine-containing waste PL to the heating device 5 can be adjusted. Therefore, by controlling the discharge amount adjusting device, it becomes possible to appropriately control the amount of chlorine supplied to the heating device 5.

In the heating device 5, the biomass ash BA2 and the chlorine-containing waste PL are heated together, so that the alkali metal in the biomass ash BA2 reacts with chlorine in the chlorine-containing waste PL to generate an alkali metal chloride. ..

In order to efficiently generate the alkali metal chloride formation reaction in the heating device 5, it is desirable that the biomass ash BA2 and the chlorine-containing waste PL are heated in a sufficiently mixed state, and therefore, it is shown in FIG. In the embodiment, an internal combustion type rotary kiln is used as the heating device 5. If the rotary kiln is a rotary kiln in which the fired portion rotates, the heat treatment can be performed while physically and continuously mixing and stirring the biomass ash BA2 to be heat-treated and the chlorine-containing waste PL. be.

The heating device 5 is not particularly limited as long as it can heat the biomass ash BA2 and the chlorine-containing waste PL at 650 ° C to 1000 ° C, and is a fixed furnace, a stoker furnace, a rotary kiln, a fluidized bed furnace, a vertical furnace, and the like. A heating furnace such as a multi-stage furnace can be used. Of these, a rotary kiln is preferable from the viewpoint of being able to perform the above-mentioned physical stirring.

In the heating device 5, the combustion gas G1 injected from the internal combustion burner 51 flows in the direction of the flow of the mixture of the biomass ash BA2 and the chlorine-containing waste PL. As a result, the gas components generated by heating and burning the biomass ash BA2 and the chlorine-containing waste PL move to the combustion furnace 8 by the flow of the combustion gas G1. The flow of the combustion gas G1 generated by the injection of the atmosphere A is formed by the air supply fan F1 and the intake fan F3.

The gas components generated by heating and burning the above-mentioned biomass ash BA2 and chlorine-containing waste PL include, in addition to a part of volatilized alkali metal and chlorine, tar and carbon monoxide derived from combustion of chlorine-containing waste PL. And dioxins.

From the heating device 5, in addition to the biomass ash BA2 from which the alkali metal has been removed, the combustion residue of the chlorine-containing waste PL, and the alkali metal chloride derived from the alkali metal of the biomass ash BA2 and the chlorine of the chlorine-containing waste PL. Things are discharged. The heat-treated product BA3, which is a mixture of these, is sent to the washing device 6.

In the water washing apparatus 6, after the heat-treated product BA3 and water W1 are mixed to generate the slurry S1, the slurry S1 is continuously stirred to dissolve the alkali metal chloride in the heat-treated product BA3 in the liquid phase.

The water washing device 6 is provided with a supply hopper 61 for the heat-treated product BA3 and a water W1 supply device 62, and mixes the heat-treated product BA3 and water W1 and stirs the slurry S1 produced by the mixing. A slurry stirring device 63 for this purpose is attached. A crushing device for crushing the large-diameter material in the received heat-treated product BA3 to an appropriate size may be attached to the upstream side of the supply hopper 61. This crushing device may be appropriately used depending on the state of the heat-treated product BA3 supplied from the heating device 5.

As the slurry stirring device 63, for example, a general paddle type or screw type may be used, and in the embodiment shown in FIG. 1, a stirring blade is provided.

The slurry S1 after the alkali metal chloride is dissolved in the liquid phase is sent to the solid-liquid separation device 7. Here, for transporting the slurry S1 to the solid-liquid separation device 7, a normal slurry liquid transport device (not shown) such as a slurry centrifugal pump, a piston pump, and a mono pump may be used.

As the solid-liquid separator 7, a filter press, a pressurized leaf filter, a screw press, a belt press, a normal filtration device such as a belt filter, or the like may be used, and in the embodiment shown in FIG. 1, a filter press is used. There is.

The solid-liquid separation device 7 uses the conveyed slurry S1 as BA4 (solid phase) (hereinafter, this may be referred to as “cake BA4”), which is a cake made of a heat-treated product BA3 dealkalimetalized. It is separated into wastewater W2 (liquid phase) containing alkali metal.

The combustion furnace 8 is arranged directly connected to the exhaust port of the heating device 5, and includes an exhaust gas combustion burner 81 for burning the combustion gas G1.

The combustion furnace 8 is provided for burning tar, carbon monoxide, and dioxins in the combustion gas G1 to make them harmless, but simply burning the combustion gas G1 will generate new dioxins. there is a possibility. Therefore, the fuel of the burner 81 for exhaust gas combustion has a low hydrocarbon content in order to suppress the regeneration of dioxin, and can generate a combustion temperature of 900 ° C. to 1250 ° C. that can reliably decompose tar and the like. From the viewpoint that pulverized coal, natural gas (LNG) or kerosene is preferably used.

In the combustion furnace 8, since the atmosphere A is introduced by the air supply fan F2 as the combustion gas of the exhaust gas combustion burner 81, the exhaust gas G2 exhausted from the combustion furnace 8 has a larger air volume than the combustion gas G1. The temperature is rising. Therefore, in order to use the sensible heat of the exhaust gas G2 as a heat source in the preheating device 3, the exhaust port of the combustion furnace 8 is connected to the cyclone 3b. The flow of the exhaust gas G2 is formed by the air supply fan F1, the air supply fan F2, and the intake fan F3.

The gas treatment agent spraying device 9 is provided for spraying the gas treatment agent to the exhaust gas G3 exhausted from the preheating device 3. The exhaust gas G3 may contain hydrogen chloride gas derived from chlorine-containing waste, and a gas treatment agent is sprayed on the exhaust gas G3 in order to detoxify the gas.

As the gas treatment agent, from the viewpoint of neutralizing hydrogen chloride gas to make it harmless, any one of quicklime (CaO), slaked lime (Ca (OH) ₂ ) and baking soda (NaHCO ₃ ) is preferable, and it is obtained by neutralizing. Quicklime or slaked lime is more preferable from the viewpoint of utilizing the obtained chloride as a chlorine source in the heating device 5, and slaked lime is further preferable from the viewpoint of reaction efficiency and handling.

The gas treatment agent is preferably powder from the viewpoint of handling, and the size of the gas treatment agent is preferably 200 μm or less from the viewpoint of reaction efficiency and forming a good mixed state with the exhaust gas G3. Here, the average particle size of the gas treatment agent is a value measured by a laser diffraction particle size distribution measuring device using ethanol as a dispersion medium.

The exhaust gas G4 containing the gas treatment agent reaches the solid air separation device 10, and on the filter cloth surface of the solid air separation device 10, for example, the bag filter, the neutralization reaction product P1 (derived from hydrogen chloride gas and the gas treatment agent) ( Solid) is produced.

In the solid air separation device 10, the exhaust gas G5 after the hydrogen chloride gas is removed is exhausted to the outside of the system, and the neutralization reaction product P1 is separated and recovered.

When quicklime (CaO) or slaked lime (Ca (OH) ₂ ) is used as the gas treatment agent, calcium chloride is obtained as the neutralization reaction product P1. Here, since the calcium component in calcium chloride can be effectively used as a raw material for cement, calcium chloride may be used as a chlorine source instead of the chlorine-containing waste PL. Therefore, in the embodiment of FIG. 1, the recovered neutralization reaction product P1 can be transported to the waste supply device 4.

Next, a method for removing the alkali metal will be described. FIG. 2 is a flow chart of the alkali metal removing method of the present invention according to the embodiment of FIG.

The alkali metal removing method shown in FIG. 2 includes a preheat treatment step ST1 for preheating powdered biomass ash BA1, a heat treatment step ST2 for heating the preheated biomass ash BA2 and chlorine-containing waste PL together, and heating. It is provided with a water washing treatment step ST3 for dissolving the alkali metal chloride contained in the heat-treated product BA3 obtained in the treatment step ST2 in water.

In the preheat treatment step ST1, it is preferable to preheat the received biomass ash BA1 so that the temperature becomes 550 ° C to 750 ° C. In order to efficiently perform this preheat treatment, the particle size of the biomass ash BA1 to be preheated is preferably pulverized in advance to 5 mm or less, preferably 4 mm or less, and more preferably 3 mm or less, if necessary. The particle size of the biomass ash refers to the minimum value of the size of the sieve through which the biomass ash passes.

As the heat source in the preheat treatment step ST1, the sensible heat of the exhaust gas G2 obtained by detoxifying the combustion gas G1 discharged from the heat treatment step ST2 of the next step by combustion is used. The temperature of the exhaust gas G2 is preferably 900 ° C. or higher, more preferably 950 ° C. or higher at the inlet of the cyclone 3b in FIG. When the temperature of the exhaust gas G2 is this temperature, the temperature of the exhaust gas G2 that has moved to the cyclone 3a after the heat exchange in the cyclone 3b is 400 ° C. to 500 ° C., and the temperature of the exhaust gas G3 after the heat exchange in the cyclone 3a is The temperature is 250 ° C. or lower, while the temperature of the biomass ash BA2 preheated by heat exchange between the cyclone 3a and the cyclone 3b is 400 ° C. or higher at the outlet of the cyclone 3b.

The biomass ash BA2 preheated to 400 ° C. or higher is sent to the heat treatment step ST2.

In the heat treatment step ST2, the biomass ash BA2 is heated together with the chlorine-containing waste PL to react the alkali metal in the biomass ash BA2 with the chlorine in the chlorine-containing waste PL to cause the alkali metal chloride. To generate. At this time, the generated alkali metal chloride is fixed to the heat-treated product BA3, which is the residue after the heat treatment.

The chlorine-containing waste PL heated together with the biomass ash BA2 is not particularly limited as long as it contains 1.2% by mass or more of chlorine and does not contain a large amount of alkali metal, and is waste poly. Waste plastics containing at least one organic chlorine in a monomer such as vinyl chloride and waste containing inorganic compound chlorine such as calcium chloride can be effectively used. Here, the concentration of chlorine in the chlorine-containing waste PL can be measured by a well-known method, for example, JIS K 7229 "Method for quantifying chlorine in chlorine-containing resin", or simply JIS R. A method based on 5204 “Method for analyzing fluorescent X-rays of cement” is preferably exemplified.

The ratio of the biomass ash BA2 treated in the heat treatment step ST2 to the chlorine-containing waste PL is the molar amount (A) of all alkali metal components in the biomass ash BA2 provided to the heat treatment step ST2 during a unit time. The ratio A: B to the molar amount (B) of total chlorine in the chlorine-containing waste PL subjected to the heat treatment step ST2 during the unit time is preferably 1: 1.5 to 1: 5, more preferably. It is set to be 1: 2 to 1: 5. When this ratio A: B is smaller than 1: 1.5, all of the alkali metal components treated in the heat treatment step ST2 may not be able to react with chlorine because the amount of chlorine is small. Further, when the ratio A: B is larger than 1: 5, the amount of chlorine volatilized and dissipated may increase and the progress of corrosion of the equipment may be accelerated.

The size of the chlorine-containing waste PL is preferably 80 mm or less, more preferably 40 mm or less, and particularly preferably 10 mm or less, from the viewpoint of efficiently performing the reaction with the biomass ash BA2. The size of the chlorine-containing waste refers to the minimum value of the size of the sieve through which the chlorine-containing waste passes.

Further, from the viewpoint of efficiently reacting the biomass ash BA2 and the chlorine-containing waste PL, it is preferable to heat the biomass ash BA2 and the chlorine-containing waste PL in a sufficiently mixed state, and mix them. A heat treatment method having an effect, for example, a heat treatment using a rotary kiln is preferable.

The heating temperature in the heat treatment step ST2 is set from the viewpoint of not melting the biomass ash BA2 while efficiently performing the reaction of forming the alkali metal chloride by the alkali metal in the biomass ash BA2 and the chlorine in the chlorine-containing waste PL. 650 ° C to 1000 ° C is preferable, 700 ° C to 950 ° C is more preferable, and 750 ° C to 950 ° C is particularly preferable. Here, if the heating temperature is less than 650 ° C., the reaction of chloride roasting of the alkali metal becomes insufficient, and the alkali metal chloride may not be produced or the production efficiency may be lowered. Further, when the heating temperature exceeds 1000 ° C., the biomass ash BA2 is partially melted or the diameter is increased, so that the reaction efficiency of chloride roasting is lowered.

The heating time in the heat treatment step ST2 may be set within the range of 10 minutes to 2 hours depending on the heating temperature. This heating time needs to be short when the heating temperature is high and long when the heating temperature is low, from the viewpoint of sufficiently reacting the alkali metal in the biomass ash BA2 with chlorine in the chlorine-containing waste PL. There is. Specifically, when the heating temperature is 650 ° C, it is 1 hour or more and 2 hours or less, and when the heating temperature is 1000 ° C, it is 10 minutes or more and 30 minutes or less.

The atmosphere in the heating device of the heat treatment step ST2 is not particularly limited and may be an oxidizing atmosphere or a reducing atmosphere, but the atmosphere is preferable from the viewpoint of convenience.

The subsequent water washing treatment step ST3 is a step of dissolving the alkali metal component that has become a water-soluble chloride in the heat treatment step ST2 in water to produce cake BA4 made of biomass ash with reduced alkali metal.

As the solvent and cake washing water used in the water washing treatment step ST3, working water (fresh water) is preferable. Both potassium chloride (KCl) and sodium chloride (NaCl) have very high solubility in water, and the solubility does not change significantly even if the water temperature is changed. Therefore, water W1 used as a solvent is a heat-treated product of normal temperature water. An amount of 3 times or more, preferably 4 times or more, more preferably 5 times or more the mass of BA3 may be used.

Further, as for the water used as the cake washing water in the solid-liquid separator 7, the amount of water at room temperature is 3 times or more, preferably 4 times or more, more preferably 5 times or more the mass of the heat-treated product BA3. It may be used.

The stirring time of the slurry S1 in the water washing treatment step ST3 is preferably 10 minutes or more, more preferably 15 minutes or more, and particularly preferably 20 minutes or more. Generally, alkali metal chloride is very soluble in water, so no special conditions are required for stirring the slurry S1.

Since the concentration of the alkali metal component in the cake BA4 obtained in the water washing treatment step ST3 is reduced to 2.0% by mass or less, more typically 1.5% by mass or less, it is effectively used as a raw material for cement or the like. be able to.

Hereinafter, specific test examples will be shown in order to explain the present invention in more detail, but the present invention is not limited to the aspects of these test examples.

As the biomass ash BA1, fly ash collected by an exhaust gas dust collector (bug filter) of a biomass power generation plant (circulating fluidized bed boiler) was used. Table 1 shows the chemical composition of biomass ash BA1 obtained by ICP emission spectroscopy analysis of acid decomposition samples for alkali metals and fluorescence X-ray analysis of pellet samples for other chemical components. show. In addition, R _{2 O of Table 1 shows the value of "R 2} O = Na ₂ O + 0.658 × K ₂ O" as the total amount of alkali metal components in this composition.

Moreover, when the particle size distribution of the biomass ash BA1 shown in Table 1 was measured based on the laser diffraction / scattering method, the D ₁₀ value was 4.4 _{μm, the D 50} value was 20 μm, and the D ₉₀ value was 64 μm. Note that, for example, the D ₁₀ value means a particle diameter at cumulative 10% in the particle size distribution based on volume.

In the above biomass ash BA1, the chlorine content Cl (PL) (mol) in the chlorine-containing waste PL is _{higher than the content R 2} O (BA1) (mol) of the alkali metal component in the biomass ash BA1. _{R 2 O (BA1): Cl} (PL) = 1: 2 and comprising an amount, after mixing the waste polyvinyl chloride crushed to sieve was Tooru Tamotsu the sieve 1 mm, the alkali metal removal device 1 shown in FIG. 1 The content of the alkali metal component of cake BA4 was compared with and without the preheat treatment step. The results are shown in Table 2.

In each test with or without the preheat treatment step, the heat treatment step and the water washing treatment step had the same conditions as described below.
Temperature of the heating part of the rotary kiln used for heat treatment: 950 ° C ± 25 ° C
Heat treatment time: 10 minutes (Rotary kiln rotation speed is the same in both tests)
Heat-treated product in water washing treatment BA3: Water W1 = 1: 4
Stirring time in water washing treatment: 10 minutes The temperature of biomass ash BA2, which is a difference depending on the presence or absence of the preheat treatment step, was 25 ° C without the preheat treatment step and 600 ° C with the preheat treatment step. ..

As can be seen from Table 2, the alkali metal content of the biomass ash is low when there is a preheat treatment step. This is because the biomass ash sent to the heat treatment process was preheated, so that the temperature range in which the alkali metal changes to chloride in the heat treatment process occurs quickly is reached, and the temperature range continues for a long time. It is thought that this is due to.

1 Alkali metal removal device 2 Combustion ash supply device 3 Preheating device 3a, 3b Cyclone 4 Waste supply device 5 Heating device 51 Internal combustion burner 6 Water washing device 61 Heat-treated product BA3 supply hopper 62 Water W1 supply device 63 Slurry stirring device 7 Solid-liquid separation device 8 Combustion furnace 81 Burner for exhaust gas combustion 9 Gas treatment agent spraying device 10 Solid air separation device A Atmosphere BA1, BA2 Biomass ash BA3 Biomass ash and chlorine-containing waste heat-treated product BA4 Biomass ash and chlorine-containing waste Cake of heat-treated product F1, F2, F3 Fan G1 Combustion gas G2, G3, G4, G5 Exhaust gas P1 Neutralization reaction product PL Chlorine-containing waste S1 Slurry W1 Water W2 Drainage

Claims (11)

A device for removing alkali metals from biomass ash.
A combustion ash supply device for supplying the biomass ash and
A preheating device for preheating the biomass ash supplied from the combustion ash supply device, and
A waste supply device for supplying solid chlorine-containing waste,
A heating device for heating the preheated biomass ash supplied from the preheating device and the solid chlorine-containing waste supplied from the waste supply device together to form an alkali metal chloride.
A water washing device for washing the heat-treated product of biomass ash and chlorine-containing waste generated in the heating device with water to elute the alkali metal forming the chloride into the washing liquid.
A solid-liquid separation device for solid-liquid separation of the slurry discharged from the water washing device and recovery of the cake of the heat-treated product.
An alkali metal removing device comprising a combustion furnace for burning the combustion gas from the heating device and supplying the exhaust gas after combustion to the preheating device. A gas treatment agent spraying device for spraying the gas treatment agent on the exhaust gas from the preheating device, and
The alkali metal removing device according to claim 1, further comprising a solid air separating device for solid-gas separating the exhaust gas to which the gas treatment agent is sprayed. The alkali metal removing device according to claim 1 or 2, wherein the heating device is a rotary kiln. The alkali metal removing device according to any one of claims 1 to 3, wherein the preheating device is a cyclone. The alkali metal removing device according to any one of claims 1 to 4, wherein the combustion furnace uses any one of pulverized coal, natural gas, and kerosene as fuel. The alkali metal removing device according to any one of claims 2 to 5, wherein the gas treatment agent is slaked lime. A method of removing alkali metals from biomass ash,
A preheat treatment step for preheating the biomass ash and
A heat treatment step of heating the preheated biomass ash and chlorine-containing waste together, and
A method for removing an alkali metal, which comprises a washing treatment step of dissolving an alkali metal chloride contained in the heat-treated product obtained in the heat treatment step in water. The alkali metal removing method according to claim 7, wherein the preheat treatment step is a step of preheating the biomass ash to a temperature of 400 ° C. or higher. The alkali metal removing method according to claim 7 or 8, wherein the chlorine-containing waste is polyvinyl chloride. The alkali metal removing method according to any one of claims 7 to 9, wherein the size of the biomass ash is 5 mm or less. The alkali metal removing method according to any one of claims 7 to 10, wherein the size of the chlorine-containing waste is 80 mm or less.

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