JPS5858134A - Promotion of additional desulfurization of flue gas by using solid waste material of fluidized bed combustion process - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the technology of fuel-burning fluidized bed combustion equipment. More particularly, the present invention relates to a method of using waste solids from a fluidized bed combustion process to further desulfurize flue gas.

Fluidized bed combustion in which a sulfur-containing fuel is burned in a bed of a receptor (e.g. limestone, dolomite, etc.) and the sulfur oxides are reacted with or captured by the alkaline compounds (CaO1Na20, K2O) of said receptor The device characteristically has poor receptor utilization. Furthermore, when solid fuels whose ash contains a significant alkaline content are combusted in fluidized bed combustors, fly ash is produced which is more chemically reactive than the products produced by conventional combustion techniques. Although these ash fractions have considerable potential sulfur scavenging capacity, their utilization is also inadequate. For example, when bituminous coal is burned with a limestone receptor, only 25-50% of the theoretical alkalinity value and 10-20% of the ash content of the receptor is utilized.

The aim of the present invention is to increase the economics of the fluidized bed combustion process by fully exploiting the alkaline chemistry in the useful waste produced. Fluidized bed combustion must act as a calciner for acceptors that produce oxides from carbonates, hydroxides, bicarbonates, etc. In the most widely used dry or wet flue gas deflow processes, special consideration must be taken to obtain a finely ground or precalcined receptor.6 Low-cost Improvements According to the Invention According to the present invention, the fluidized bed combustion process can be endowed with the ability to produce finely ground and pre-calcined receptors.

The present invention is a flue gas desulfurization process that uses solid waste from a fluidized bed combustor, where the solid waste is enriched with alkaline chemistry to provide scavenging of sulfur oxides in the combustion products. The combusted limestone acts as an alkaline acceptor in the fluidized bed combustor and is removed from the fluidized bed in the form of powder contained in the effluent stream or in the form of solid waste exiting the fluidized bed combustor nozzle. .

The coarse solid waste is combined with the powder and the mixture of coarse particles and powder is finely divided into powder, slurry or solution form before being reintroduced to the fluidized bed. Alternatively, the mixture can be used as a collector in a wet or dry scrubber.

In the present invention, the solid waste of fluidized bed combustion is brought into a finely divided and chemically reactive state in the form of a dry powder, a thick alkaline slurry or a watery alkaline solution for use in: provided.

(al floor, freeboard 1' (freeboard
), the gas collection base (multi-bed unit), the stage before the secondary dust collection, the stage before the final dust collection (along with dry gas collection), etc. to improve the fluidized bed combustion method. Plan.

(b) Use as a gas collection line in other conventional combustion systems producing gases containing sulfur oxides. This use is
A fluidized bed combustion unit can be used to produce a collection system. If the ash from the conventional combustion system is reactive, 1 it can be incorporated into the process.

In this way, the normally occurring fluidized bed combustion waste can be activated, improving the waste removal efficiency and improving the acceptor utilization efficiency of the basic fluidized bed combustion process. In addition, a dry gas collection device (Bruven spray-dryer design (p.
Efficiency used for desulfurization of gases from conventional combustion devices incorporated into prior art gas collection devices such as wet gas collection devices (using Venturi designs or tray designs) For the production of good dry or wet gas collection lines, it becomes possible to use fluidized bed combustion waste.

1 is a schematic diagram illustrating the general principle of the method;

In a fluidized bed combustion device (hereinafter abbreviated as FBC device) 10, fuel particles 14 such as coal are mixed with air 12.
is used to combust in a fluidized bed of receptor particles 16, such as limestone. The particle size of the receptor particles is 3.
2 + m X O (-inch XQ). The FBC device 1o acts as a basic smoker for the receptor particles 16, and generates alkaline compounds (CablNa 20, K2O, etc.), and these alkaline compounds react with sulfur oxides generated by combustion to generate sulfur oxides. Capture.

FBC device 10 produces two forms of alkaline waste. The first form of product is small-sized dust particles (fly ash) collected from the flue gas, and the second form of product is typically in the size range 3.2 + aX Q (-in. )"t' Apparatus 10 (7) These are coarse particles 2o coming out from the pipe port or extraction port.

The FBC device 1o is an exhaust gas 11 containing SO2 and SO3.
and this gas would exceed environmental standard limits without the invention. A conventional combustion device 22 can be placed next to the FBC device 10, and this device 2
2, the fuel particles 26 are combusted using air 24 to produce conventional ash particles 28 with a high alkaline gas scavenging value.

The coarse particles 20 and, if the alkali value is high, the conventional ash particles 14 are fed to a mechanical grinding device 30 to grind and disintegrate the waste particles and ash particles into finely divided particles. Particles 33 are created. , examples of the grinding device 30 include a ball mill or a roll mill.
) k can be listed.

The preferred particle size range of the finely divided particles 33 is 70
The particle size range is from 90% by weight to pass through a 200 mesh sieve. Alternatively, as shown in FIG. 1, coarse waste particles 20 and ash particles 28 may be introduced into a treatment vessel where they are treated with a water/steam treatment 32 prior to mechanical grinding. Hot waste particles 20 by water/steam treatment 32
and ash particles 28 burst into finely divided particles 33
The generation of is encouraged.

In FIG. 1 illustrating an embodiment of the invention, finely divided dry particles 33 with increased alkali number are combined with fine dust particles 18 and injected into a fluidized bed combustion apparatus lO via a feed line 40. Desulfurization inside the device 10 is strongly promoted. Finely divided particles 33 and fine dust particles 18 are passed through a supply line 41 to a dry flapper.
42 to remove sulfur oxides from the exhaust gas 11. The exhaust gas 11 is then sent to a final dust removal device 52 where the resulting dry solid waste 56 is
is removed and the purified gas 54 is discharged to the atmosphere.

In another embodiment of the invention, shown in FIG.
tor) 34, where it is mixed with water 36 to form a concentrated alkaline slurry 3 containing calcium hydroxide.
You can also make 8. This thick alkaline slurry 38 is supplied to the fluidized bed combustion apparatus 1 through a supply line 40.
The gas is injected into the exhaust gas 11, and is supplied to the dry sfluppers 42 via the supply line 44 to react with the sulfur oxides in the exhaust gas 11 and capture the sulfur oxides.

Finely divided dry alkaline waste particles 33 or thick alkaline slurry l -3g are fed into a fluidized bed combustion apparatus 10.
By injecting into the gas, the direct desulfurization properties can be improved to such an extent that final gas collection is often unnecessary.

In yet another embodiment, shown in FIG. 1, finely divided dry particles 33 and fine dust particles 18 are combined and fed to a digester/hydrator 34 where they are mixed with water to form calcium hydroxide. A thin alkaline gas collection liquid 44 containing . A thin alkaline gas collection liquid 44 is injected into the wet flappers 46, and the exhaust gas is
Sulfur oxides are removed from 1 to produce a purified gas 50, and the spent sludge 48 is extracted.

FIG. 2 shows a fluidized bed 64 consisting of fuel particles 70 and receptor particles 72 having a freeboard area 62 above a fluidized bed 64 which is fluidized by air 68 flowing upwardly through a grid 66. The method of the present invention employs a digester/hydrogenator (a general method is shown in FIG. FIG. 3 is a diagram illustrating an embodiment of the present invention in more detail.

Exhaust gas 81 is discharged from gas column 74 and passes through dust collector 7
6, where fine dust particles with an alkaline value (
Fly ash) 77 is removed and reinjected into the fluidized bed 64. Alternatively, some of the fine dust particles 77 may be conveyed to the consumable holding container 98. After exiting the precipitator 76, the exhaust gas 81 is routed through an air header 100 to a gas/solids contact dry flapper 102. Exhaust gas 104 at a temperature above the dew point passes through a baghouse 108 where dry solid waste 112 is removed and the purified gas is released into the atmosphere through a chimney 110. .

As shown in FIG. 2, a carbon combustion cell (CBC) has a freehold area 80 above a fluidized bed 82 which is fluidized by air 86 flowing upwardly through a grid 84.
78 can also be incorporated into the plant. Some of the fine dust particles 77 may also be injected into the fluidized bed 82 to increase the desulfurization capacity of the bed 82.

Coarse waste particles 61 from the main cell 60 are conveyed to a drawer 9 through the cell port/outlet to an attritor/disintegrator and cooler 90 where the hot waste particles 61 (typically 538-8
(1000-1500F) is cooled by air flow 92. Coarse waste particles 83 coming out of the carbon combustion cell 8 are extracted from the cell's pipe opening/sampling cap and conveyed to a grinder/disintegrator/cooler 90. Reactive fly ash from adjacent conventional combustion equipment 88
It can also be fed to the upper part of the attritor/disintegrator/cooler 90.

The combined coarse waste particles flow through a grinder/disintegrator 90 and are processed by a mechanical grinder 94 to a particle size that preferably allows 70 to 90% by weight to pass through a 200 mesh screen. As such, the particle size is reduced. The finely divided particles are pneumatically conveyed by air stream 96 back to the top of attritor/disintegrator 90 where they are combined with finely divided reactive fly ash 88 . The combined finely divided particles 97 are then conveyed by air pressure to a consumable holding container 98. These finely divided particles exit from the bottom of the holding vessel 98 and are transferred to the digester/hydrogenator 1.
14 where it is mixed with water to form a thick alkaline slurry containing calcium hydroxide. If necessary, it is treated with a wet milling process using a milling device 116 and pumped back to the digester/hydrogenator 116.

A thick alkaline slurry 118 is pumped through a feed line 117 to a gas/solid contact dry scrubber.
1 (j2) and inject the slurry into said slapper by any suitable injection means of the prior art, such as a nozzle device. At the same time, via feed line 115, the concentrated alkaline sludge IJ-118 is transferred to the fluidized bed combustion apparatus. Pump the slurry to several locations on the floor 6.
4 height point, freehold area 62 height point,
They are a gas column 74 and a dust collector 76. To this end, the prior art pouring slurry, for example a nozzle, is rapidly dried to a fine powder, reacts with the sulfur oxides, and traps the sulfur oxides in a fluidized bed combustion device (dry This directly improves the operating characteristics of the flapper (acting as a flapper).

In another embodiment of the process of the invention (the general principle is shown in FIG. 1), shown in detail in FIG. 3, the fluidized bed combustion waste is finally brought into a finely divided state and then Injected by air pressure in the form of a dry powder. Components that are the same as those shown in FIG. 2 are designated by the same reference numerals in FIG.

A fluidized bed combustion apparatus 6o is one having a freeboard area 62 above a fluidized bed 64 consisting of fuel particles 70 and receptor particles 72 which are fluidized by air 68 flowing upwardly through a grate 66. Or it has two or more main cells. The exhaust gas 81 is passed through a gas column 74 to a collector 76 where fine dust particles (fly ash) 77 having an alkaline value are removed and reinjected into the fluidized bed 64 . Exhaust gas 81 is directed through air header 100 to gas/solid contact dry scrubber nos. 122. The exhaust gas 104, which is at a temperature above the dew point, passes through a baghouse 108 where dry solid waste is removed and the purified gas is released to the atmosphere.

As illustrated in FIG.
) 78 can also be incorporated into the plant. Also, some of the fine dust particles 77 can be injected into the fluidized bed 82 to increase the desulfurization capacity of the fluidized bed.

Coarse waste particles 61 coming out of the main cell 60 are transferred to the cell pipe opening/
The hot waste particles 61 are extracted from the extraction port and conveyed to a grinder/disintegrator/cooler 90 where the hot waste particles 61 are cooled by an air flow 92 . Coarse waste particles 83 are similarly extracted from the pipe/extraction port of the carbon combustion self 8 and transferred to the grinder/disintegrator 9.
Transport to 0.

Reactive fly ash 88 from an adjacent conventional combustion device may be fed to the top of the fort crusher/disintegrator 90.

The coalesced waste particles flow through a grinder/disintegrator 90 and are treated in a mechanical crusher 94 in a trench which preferably results in a particle size range of 70 to 90 weight particles passing through a 200 mesh screen. Particle size is reduced. Alternatively, the coarse waste particles can be subjected to high velocity steam/water injection treatment in the attritor/disintegrator 90. The steam/water injection process provides in-situ/remote digestion/waterification to yield a finely divided limestone product suitable for injection. Attritor/disintegrator/cooler 9 shown as an external device in Fig. 3
It is easy to understand that 0 can also be integrated into a fluidized bed combustion apparatus.

The finely divided particles are then conveyed by air stream 96 back to the top of attritor/disintegrator 90 where they are combined with reactive fly ash 88. The combined finely divided particles are conveyed pneumatically and injected into a gas/solid contact dry scrubber 122 by a suitable injection means. Simultaneously, finely divided dry particles 124 are injected into the fluidized bed combustor 60 at the level of the bed 64, at the level of the freeboard zone 62, into the gas column 74 and into the precipitator 76. Any conventional and suitable injection means may be used for this purpose. The finely divided dry particles react with and scavenge the sulfur oxides, directly enhancing the operating characteristics of the fluidized bed combustor, which acts as a "dry scrubber".

In another embodiment of the method of the invention (the general principle is shown in FIG. 1), shown in detail in FIG. A dilute alkaline gas capture liquid or flue gas desulfurization solution is prepared for use.

Some parts have been omitted from FIG. 4 for clarity of illustration. Components omitted from FIG. 4 are common to those illustrated in FIGS. 2 and 3, which include fuel particles 70 and receptors being fluidized by air 68 flowing upwardly through grid 66. Fluidized bed combustion apparatus 60. having one or more main cells 60 with a fluidized bed 64 consisting of particles 72 and a fluidized bed 64 consisting of particles 72. Exhaust gas 81 passes through a gas column 74 and is sent to a precipitator 76 to remove fine dust particles (fly ash) 77 having an alkaline value, and is reinjected into the fluidized bed 64. Air flows upward through a grid 84. A carbon combustion cell 8, which can be incorporated into a plant, with a freeboard area 80 above a fluidized bed 82, which is fluidized by 86, a fluidized bed 8
A portion of the fine dust particles 77 that can be injected into
Coarse waste particles 61 are conveyed to the alkaline material holding container 130 shown in Figure 4. Similarly, the alkaline substance holding container 13 is extracted from the pipe port/extraction cap of the carbon combustion self 8.
Coarse waste particles 83 conveyed to the alkaline storage container 130, as well as fine dust particles 77 and reactive fly ash 88, etc. from an adjacent conventional combustion apparatus, which are fed to the alkaline holding vessel 130, are omitted.

In the embodiment shown in FIG. 4, a source of coarse fluidized bed combustion waste particles, a source of fine dust particles, and a source of reactive fly ash are illustrated as being in separate locations. Therefore, each of the above-mentioned materials can be transported from a distant place and supplied to the alkaline substance holding container 130.

As shown in FIG. 4, the pre-milled material 132 having a sufficiently small particle size is conveyed directly from the alkaline material holding container 130 to the digester/hydrogenator/mixer 140. Larger coarse particles are sent from holding vessel 130 to attritor/disintegrator 134 . Coarse waste particles are removed by mechanical grinding equipment 138
preferably between 70 and 90% weight
The particle size is reduced to a particle size that passes through a 0.00 mesh sieve. Next, the finely divided particles are
36 pneumatically conveyed by the attritor/disintegrator 134
sent to the top of the page. The finely divided particles 135 are then conveyed to a holding container 139 by air pressure. A portion of the finely divided particles 135 is stored in a holding container 139.
is conveyed to the outside from the upper part of the exhaust gas 81 and joins with the exhaust gas 81.

The remainder of the finely divided particles 135 is stored in a holding container 139.
and enters the digester/hydrator 140.

In the digester/waterizer 140, the finely divided particles are mixed with water and, if necessary, treated in a wet miller 142 to form an alkaline gas-trapping liquid 144 containing calcium hydroxide. .

The alkaline gas capture liquid 144 is pumped to a conventional final wet suffler 146 and supplied to a liquid reservoir 147;
For example, sulfur oxides are removed by contact with a spray nozzle. Spray nozzle 1 from the bottom of the reservoir 147
The gas capture liquid is returned to the gas capture chamber via 48. The spent gas capture liquid is pumped to a separator 156 to remove the sludge waste 150 and the reused water 158 is sent to the digester/
It is refluxed to the waterizer 140. The purified gas exits through a mist remover 151 which is periodically flushed with water 152 and is discharged through a reheater 154 to the atmosphere.

The above embodiments are provided for illustrative purposes only and are not intended to limit the technical scope of the present invention. The scope of the invention is defined in the claims, and all equivalents are included within the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic process diagram showing the general principle of the present invention. Figure 2 shows how fluidized bed combustion waste can be used to act as a "dry collector" to improve the operating characteristics of fluidized bed combustion (FBC) processes or to collect gases from other conventional combustion units. It is a schematic process diagram showing an example in which This example is a digester/hydrator.
r) to make a thick alkaline slurry.
This is an example of pressurized injection into various parts of a fluidized bed combustion equipment and a dry scrubber. Figure 3 shows the use of fluidized bed combustion (FBC) waste to act as a "dry collector" to improve the operating characteristics of fluidized bed combustion or to collect gases from other conventional combustion units. FIG. 2 is a schematic process diagram showing an example in which In this example, fluidized bed combustion is used. FIG. 4 is a schematic process diagram illustrating an example of the use of fluidized bed combustion (FBC) waste in the production of alkaline gas capture liquid for flue gas devaluation using a conventional final wet gas capture process. I'll go. In the figure, 10 is a fluidized bed combustion device, 22 is a storage/combustion device,
30 is a grinding/disintegration processing device, 42 is a dry flapper,
46 is a final wet flapper, and 52 is a final dust removal device.

Claims (1)

[Claims] 1) A method for further desulfurizing flue gas using solid waste from a fluidized bed combustion apparatus in which a sulfur-containing fuel is burned in a bed containing acceptor particles, comprising: (1) ) extracting coarse waste particles from the fluidized bed combustion apparatus; (2) grinding and disintegrating the coarse waste particles to reduce the particle size into finely divided particles having a high alkaline chemical value; and +81 the step of injecting said finely divided waste particles into said fluidized bed combustor to further desulfurize the flue gas. 2. Process according to claim 1, characterized in that it comprises another step of injecting said finely divided particles into a final gas/solid contacting device. 3) A method for further desulfurizing flue gas using solid waste from a fluidized bed combustor in which a sulfur-containing fuel is combusted in a bed containing acceptor particles, the method comprising: (1) said fluidized bed combustor; (2) grinding and disintegrating the coarse waste particles to reduce the particle size into finely divided particles having a high alkaline chemical value; (8) ) feeding the finely divided particles into a digester/hydrogenator to mix the particles with water to form an alkaline slurry; 4) injecting said alkaline slurry into a final solid/liquid contacting device. The method described in section. 5) collecting ash particles from a prior art combustion device; combining said ash particles with said coarse waste particles; and combining said combined ash particles and said coarse waste particles. and grinding and disintegrating to reduce the size of the combined ash particles and coarse waste particles into finely divided particles having a high alkali value. The method described in Section 3. 6] The step of treating the alkaline slurry formed in step (8) with a wet grinding means to reduce the particle size of particles in the slurry, according to claim 3. the method of. 7) A method for desulfurizing flue gas using solid waste from a fluidized bed combustor in which a sulfur-containing fuel is combusted in a bed containing acceptor particles, the method comprising: a step of extracting the granular waste particles; (2) a step of reducing the particle size of the coarse waste particles to crushed and disintegrated particles; (4) injecting the alkaline gas-trapping liquid into a conventional final wet gas-trapping device; 8) Collecting ash particles from a prior art combustion device and combining said ash particles with said coarse waste particles. a step of grinding and disintegrating the combined ash particles and the coarse waste particles to finely divide the combined ash particles and the coarse waste particles with a high alkali chemical value; 8. The method according to claim 7, further comprising the step of reducing the size of the particles. 9) A patent characterized in that it has a step of treating the alkaline gas-trapping liquid formed in the step (8) with a wet grinding means to reduce the particle size of particles in the gas-trapping liquid. The method according to claim 7.