JPS6249114A - Incinerated ash solidifying method - Google Patents

Abstract

PURPOSE:To make a solid form of collected ashes in a short period of time without decreasing an effect of reducing a volume of ashes and without using any cement and to prevent the ashes from being formed into lump by a method wherein powder particles of calcium compound is mixed with an incinerator or its discharged gas, the incinerated ashes including the mixed powder particles are collected from the incinerated discharged gas and the collected incinerated ashes are humidified to form a solid. CONSTITUTION:A desired amount of particle dolomite 11 of calcium compound is mixed in a refeeding circulation passage of fluidized sand by a feeding amount adjusting unit 12 and then fed into the incinerator 1 together with the fluidized sand. Either powder of CaO or CaCO2 thus generates is flown up from the fluidized bed 2 together with the ignited adhes, CaCO2 powder becomes CaO under hot temperature or a fire or combustion discharged gas, discharged out of the incinerator 1 together with the combustion discharged gas, its temperature is decreased by a gas cooling equipment 13 and almost all the adhes are collected by a dust removing equipment 14. The incinarated ashes discharged and accumulated in an ash banker 24 can turned into solidified ashes by means of particle formation or molding by a particle forming machine 16 and only by humidifying with an ash humidifying machine 15 without mixing cement or something like that.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention uses cement to incinerate incineration ash generated when incinerating materials such as municipal waste and sewage sludge in a fluidized bed type or other incinerator. It relates to a method of solidifying without

[Conventional technology]

In recent years, incineration ash generated when municipal waste and sewage sludge are incinerated has been increasingly subjected to granulation or compaction treatment to suppress the elution of harmful substances, prevent dust scattering, and facilitate handling. It's coming. A common method for this is to add 2 to 3 ounces of cement to the incinerated ash collected from the exhaust gas by a dust removal device, then humidify and knead it, and then granulate it or form it into blocks. ing.

[Problem that the invention seeks to solve]

However, such conventional methods have the following problems: (1) The volume of the material reduced by incineration is increased by adding cement, and the volume reduction effect is increased. .

(2) Cement material costs increase.

(3) Due to the action of assimilation rate regulators such as stone eel contained in cement, the solidification time becomes long (and curing is required. Depending on the case, curing may be performed using Hari-Kufu or Kuhe-wata) .

(4) Granules adhere to each other in the curing bunker and form agglomerates.

These are some of the problems.

The purpose of the present invention is to solve the above-mentioned problems of the conventional methods, and to provide a method for solidifying incinerated ash that does not use cement, does not impair the volume reduction effect, solidifies in a short time, and prevents agglomeration. That is.

[Means for solving problems]

The present invention, as a means to solve the above-mentioned problems, mixes calcium compound powder and granules into the incinerator or incineration exhaust gas when incinerating materials to be incinerated, and removes the mixed powder and granules from the incineration exhaust gas. Collect and remove the incineration ash containing
It is an object of the present invention to provide an incineration ash assimilation method characterized by humidifying and solidifying the collected incineration ash.

As the calcium compound to be mixed, powders and particles of dolomite, limestone, slaked lime, etc. are used.

The method of mixing the calcium compound powder into the incineration exhaust gas is to add the calcium compound in the form of granules to the fluidized sand in the re-input circulation path of the fluidized sand to form a fluidized bed. , a method in which it is introduced into an incinerator together with circulating fluidized sand or supplementary fluidized sand, a method in which it is blown in the form of powder into a high-temperature part (e.g. 600°C or more) of a freeboard or exhaust gas path together with transport air, a method in which granules or powder are A method is used in which the mixture is mixed with municipal waste, sewage sludge, and other materials to be combusted and then thrown into an incinerator.

[Effect]

In this way, CaCo is removed in the incinerator or in the combustion exhaust gas.
Calcium compounds mixed in the form of 3, Ca (OH) z, etc. undergo decarboxylation or dehydration reaction under high heat to produce CaO powder. This CaO powder is mixed with the incinerated ash and is carried by the exhaust gas, and is collected by a dust collector or the like. Since CaO powder is mixed in the incineration ash collected in this way, it can be solidified by humidification, and there is no need to add cement.

〔Example〕

The present invention will be explained with reference to the drawings based on examples.

In Fig. 1, 1 is an incinerator, with a fluidized bed section 2 at the bottom.
is formed, and the upper part serves as a freeboard section 3. The incinerator 1 is supplied with municipal waste 4 to be incinerated, fluidized air 5, and auxiliary fuel 6, and incineration is performed.

The noncombustibles are discharged together with the fluidized sand from the solid matter removal lower, removed by a noncombustible vibrating sieve 8, and discharged as noncombustibles 9.

The fluidized sand from which incombustibles have been removed is transported to an elevator lO for sand circulation.
The waste is lifted up and put into the incinerator 1 again.

During this re-injection of the fluidized sand, a predetermined amount of granular dolomite 11 is mixed in as a calcium compound by the supply amount regulator 12, and the fluidized sand is introduced into the incinerator I.

The input municipal waste 4 is completely combusted in the fluidized bed section 2, and some of the generated unburned matter is also combusted in the freeboard section 3. In the fluidized bed section 2, fluidized sand with a particle size of around 1 mm is suspended and fluidized by fluidized air 5, which also serves as combustion air, blown in from the floor surface. The temperature is desirably 700°C or higher), and usually 800°C or lower where there is no fear that the fluidized sand will melt.

Since the municipal waste 4 contains incombustibles such as stones, rubble, and iron, in order to prevent the concentration of incombustibles from increasing in the fluidized bed section 2 during operation, the incombustibles are extracted along with the fluidized sand from the solids removal lower. Noncombustibles are sieved by a vibrating sieve 8 with a sieve diameter of about 3 to 5 mm, and the fluidized sand under the sieve is directly lifted up by a sand circulation elevator IO and put into the incinerator 1.

The dolomite mixed in this fluidized sand is usually crushed to a particle size of 3 mm or less so that it is not discharged together with the incombustibles through the incombustible vibrating sieve 8, and the particle size is such that it can be flowed with the fluidized sand by the fluidizing air. .

In the temperature range of 600 to 800°C in the fluidized bed section 2, decarboxylation and dehydration reactions occur, and dolomite itself MgCO
Dolomite flows in the same way as fluidized sand, and crumbles while gradually producing granular CaO and CaC0 while being mixed in with the fluidized sand. The decarboxylation reaction starts at around 500°C. However, since the reaction rate slows down as the temperature decreases, it is desirable that the fluidized bed temperature be 700° C. or higher.

The CaO powder or CaCO3 powder generated in this way flies up from the fluidized bed part 2 together with the incinerated ash and becomes CaCO
3 becomes CaO due to flame and high temperature of 14Vl exhaust gas,
It is discharged from the incinerator 1 together with the combustion exhaust gas, and the gas cooling stage #
The temperature is reduced in i13, and most of it is collected in the dust removal equipment 14.

The combustion exhaust gas becomes exhaust gas that contains almost no soot and dust, and the J&
Eventually, it is emitted into the atmosphere through chimneys.

The incinerated ash collected by the dust removal equipment 14, settled by the gas cooling equipment 13, discharged and stored in the ash bunker 24 contains CaO powder, various salts, burned products, etc. in a sufficiently mixed form in advance. ing. Therefore, by simply humidifying the ash in the ash humidifier 15 without mixing cement, solidified ash can be obtained by granulation or molding in the granulator 16. In this case, CaO
Due to the heat generated by the hydration reaction, the temperature of the product rises, and it hardens in a much shorter time compared to things like Portland cement.

17 is a curing facility, and 18 is a product bunker.

In addition to CaO produced from dolomite, MgO5 derived from MgCO1 in dolomite, dQ, Δp201 originating from metal An including aluminization, which is large in municipal waste, or It also contains CaO derived from Ca compounds such as oysters and shellfish, which react with the water added to the incineration ash and release various types of hydration while also incorporating metal oxides and salts contained in the incineration ash. It produces salt, grows crystals, and solidifies the ash.

As a result, harmful components such as heavy metals in the ash are incorporated into the crystals.

Compared to CaO, M g O, Af, 0. The assimilation reaction caused by hydrates is a temperature-dependent reaction, so it is quick and has a large ability to fix harmful components.

Therefore, similar assimilation ability can be expected from limestone or crushed shellfish, but dolomite is more preferable in terms of immobilizing harmful components.

In addition, dolomite has weaker crystalline strength than limestone due to its MgC content and is more likely to become powdered by collision with fluidized sand, and the decarboxylation reaction rate of MgCO3 is different from that of CaCO3, resulting in finer CaO formation. It also has the advantage of being easy to use.

It is desirable to adjust the amount of dolomite added so that the mixing rate is appropriate for ash assimilation, and the amount added is adjusted depending on the ash production efficiency. The ratio of CaO is usually about 5 to 30%, and is adjusted depending on the condition of the solidified product and the requirements for the solidified product.

In addition, compressed air 19 is intermittently blown into the lower part of the ash bunker 24 to prevent bridging of the ash bunker 24 and to prevent the ash bunker 24 from bridging.
It is also preferable to homogenize the ash by stirring the ash ('I') for stable operation of the incineration and solidification system (liii).

J'JXW6 When an air blowing mechanism is installed, it is customary to install an exhaust bag filter 20 on the top of the ash bunker 24 to exhaust the blown air; otherwise, air containing ash from the ash conveyor etc. will come out and manipulate the environment.

Furthermore, even if slaked lime powder, CaC0, or powder is blown into the incinerator freeboard section 3 or the smoke area of the combustion exhaust gas at a temperature of 600°C or higher together with the transport air, since they are fine, dehydration and decarboxylation reactions will occur, causing the formation of limestone and dolomite. Since CaO powder is generated in the same way as in fluidized bed addition, similar ash assimilation can be expected. At temperatures below 600° C., the decarboxylation reaction rate is too slow to sufficiently calcinate to CaO.

FIG. 2 shows an embodiment of a calcium compound supply mechanism using the above-mentioned pneumatic transportation method, in which slaked lime powder or calcium carbonate powder is stored in a silo 21 equipped with a bag filter.
Place it on the pneumatic transport line by the pneumatic transport blower 22,
A predetermined amount of air regulated by a supply amount regulator 23 is guided to an incinerator or a high/L (600°C or higher) flue. It is also used to assimilate incinerated ash in a stoker furnace that does not have a fluidized bed section.

In addition to the method of charging dolomite and limestone into the furnace, it is also good to mix it with the incineration material such as municipal waste into the furnace, or to provide a completely independent charging line into the furnace.

In the case of a sludge incinerator, the particle size of the incombustibles is usually smaller than that of fluidized sand, so the sand circulation system is omitted because the sludge burns and simultaneously becomes fly ash and is entrained in the incineration exhaust gas. In such cases, it may be added to the sand supply line, added to the sludge input line, or provided with an independent input line.

Of course, the above applies to sewage sludge, human waste sludge, and other sludge incinerators and other general incinerators, even if the waste is not particularly municipal waste.

According to the embodiments described above, it has become possible to perform assimilation of incineration ash similar to cement solidification without adding cement. Furthermore, since there are no additives that are unavoidable with cement or unnecessary contaminants such as gypsum that slow down the solidification rate, it is possible to suppress the increase in electricity generated by incinerated ash. In addition, this method requires shorter solidification time than ash solidification using Portland cement, etc., and curing equipment can be saved or omitted. Also,
Since it can be substituted with limestone, which is a raw material before firing cement, or inexpensive crushed dolomite stone that can be purchased at a similar price, the cost of the solidifying material is less than half the cost in terms of effective Cadi. In particular, when dolomite is used, it has excellent solidification speed and ability to fix harmful substances.

In addition, the addition of these Ca compounds causes Ca to react with harmful components such as MCI and SOx in the exhaust gas.
It can also play a role as a SOx removal and HC1 removal device. The Ca compound for removing SOx and H1 directly serves as an ash solidifying agent.

As for the component equipment, it is only necessary to lead the dry ash from the ash bunker through a low-power humidifier to the molding machine, and the mixing of ash and cement using expensive instrumentation and the mixing of ash and cement using motorized equipment are all that is necessary. All equipment for mixing cement, such as a machine, can be omitted. In addition, it has the same effect as hot air curing or heat "iIA curing" and shortens the curing time, making it possible to reduce or eliminate the curing section capacity due to the short curing time, making storage measures much easier. Become.

〔Effect of the invention〕

According to the present invention, it is possible to provide an incineration ash solidification method that does not use cement, does not impair the volume reduction effect of incineration, solidifies in a short time, and prevents nodule formation, and has extremely great practical effects.

[Brief explanation of the drawing]

The drawings relate to embodiments of the present invention; FIG. 1 is a flow diagram, and FIG. 2 is a flow diagram of an example of a calcium compound supply mechanism. ■...Incinerator, 2...Fluidized bed section, 3...Freeboard section, 4...Municipal waste, 5...Fluidized air, 6...
- Auxiliary fuel, 7... Solid matter outlet, 8... Non-combustible material vibrating sieve, 9... Non-combustible material, 10... Elevator, 11
... Dolomite, 12... Supply amount regulator, 13...
・Gas cooling equipment, 14... Dust removal equipment, 15... Ash humidifier, 16... Granulator, 17... Curing equipment, 18.
... Product bunker, I9... Compressed air, 20... Bag filter, 21... Silo, 22... Air transport blower, 23... Supply amount regulator, 24... Ash bunker.

Claims (1)

[Claims] 1. When incinerating materials to be incinerated, calcium compound powder was mixed into the incinerator or incineration exhaust gas, and the incineration ash containing the mixed powder was collected and collected from the incineration exhaust gas. An incineration ash solidification method characterized by humidifying and solidifying incineration ash.