CA2068911A1 - Separation of pollutants in the incineration of municipal solid waste - Google Patents

Abstract

56,682 ABSTRACT OF THE DISCLOSURE
Incineration of municipal solid waste (MSW) produces pollutants including hydrochloric acid, hydro-fluoric acid, sulfur compounds particularly sulfur oxides, nitrogen oxides, carbon monoxide and flyash. Disposal of MSW by incineration is not acceptable unless these pollu-tants are eliminated or reduced to a very small fraction.
There is disclosed a method of processing the products of combustion of the incineration of MSW in whose practice the products of combustion are passed through a fluid-bed filter contactor including ceramic candle filters. The products of combustion are reacted with sorbents either in the contactor or in the channel through which the products are passed to the contactor to convert the acids and the sulfur compounds into solid particulate and reacted with reactants in the presence of catalysts in the contactor to decompose the nitrogen oxides into atmospheric gases. The particulate is filtered out by the filters and deposited as ash together with the flyash which is also filtered out.
The carbon monoxide is oxidized by the air in the contactor to carbon dioxide. The atmospheric gases are vented to the atmosphere together with the filtered products of com-bustion.

Description

2~689:~1 1 56,682 SEPARATION OF POLLUTA~TS IN TIIE
INCINERATION OF MUI~ICIPAL SOLID '.!AST~

BACKGROUND OF THE INVENTION
This invention relates to the disposal of munici-pal solid waste (MSI~) and it has particular relationsh~p to such disposal by incineration. ~his invention is inti-mately related to incineration of ~ISIr and is uniquelyapplicable to thls way o~ disposing o~ MSI7. But it is to be understood that this invention may find ada~tation in other areas, for example, in the treatment o~ flue gases of power plants whose primary source of power is fossil fuel, and that such adaptatlon is within the scope of equivalents of this application and of any patent which may issue on or as a result thereof.
As landfills for MS~J become filled and it becomes more and more n~cessary totrespass on residential areas where the landfills are decidedly unwelcome, 1t has become indispensible to create other facilities than deposit in landfills for disposing of rlSI~. Among these facilities is the incineration of the MSW, usually, at the same time t-o generate electrical power. This alternative to landfills has been put into use in a number Or states in the US, In-cineration Or the waste generates pollutants,-specirically hydrochloric acid, hydrofluorlc acid, sulfur oxides, nitro-gen oxides, carbon monoxide and flyash containing unburned carbon. It is ~ssential ~hat these pollutants be separated from the flue gas which is released to the atmosphere or that their content in the gas be reduced to a very small, harmless magnitude. Indeed~ one of the handicaps, under ' '' ' , ; ;.

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2~911 2 56,682 which inclneration Or waste ln accordance wlth prior art practice suffers, ls the failure to separate or reduce the pollutants to a harmess magnitude at a reasonable cost.
It is an obJect Or this invention to suppress the toxlcity of the flue gases and the ash in the incineration of ~lSll by separating the pollutants from the gas which is discharged to the atmosphere and rrom the ash which is de-posited.
Commercial emissions control technology, in accor-dance with thé teachings of the prior art, generally performsthe functions of particulate control, sulfur oxides (herein S0x) control, ]ICl/HF control, and nitrogen oxides (herein N0x) control in a step-wise fashion, requiring large plant space and high equipment cost. Commercial particulate con-trol devices that will remove small particles such as bag-house ~abric filters and electrostatic precipitators, operate only at limited low temperatures (~250C) (482F), are very large devices and are sensitive to flue gas and particulate conditions. They may not, for example, be efrective in the removal of very fine particles or sticky particles may raise reliability concerns, and may not ~unction well under certain flue~gas compositions.
Commercial technology of the prior art for Sx and HCl/~F removal includes both wet and dry systems operated as once-through or recovery processes. The commercial mar-~et is dominated by lime-based and sodium-based systems.
These commercial processés may be able to function with MSW
incinerators, but n~aintenance, reliability and cost factors are ma~or concerns. The temperature limitations for these 3 commercial processes would place them generally after all heat transfer equipment in the plant, so none of the equip-ment would be protected from the potentlally corrosive and fouling nature Or the combustion products.
The commerclal N0x flue gas treatment processes ` 35 are large and generally expensive, and some are very sensi-tive to particulate and to flue gas conditions, requirlng particulate removal before accepting the rlue gas, and opera-tin~ over limlted temperature ranges with uniform gas flow re~luired .

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2~8~11 3 5~,682 It ls an ob~ect of this invention to overcome the drawbacks and deficiencies Or the prlor art and to provide for the suppression of the toxicity and corroslve erfects in the incineration o~ MSI~ reliably and economically and with mlnimum maintenance requirement.
SUMMARY OF THE INVEI~TION
In accordance with this invention, there is pro-vided a method o~ separating pollutants in the incineration of municipal solid waste in whose practice the MSW is burned and converted into flue gas and ash. The flue gas is passed to a pseudo-liquid fluid-bed filter contactor in which there are filters, typically ceramic candle ~'ilters. The gas which drives the fluid-bed may be the flue gas itself, driven, ~sually by positive and negative pressure, at a high enough velocity to produce the pseudo~ uid condition. The fluid-bed may also be driven by a separate pump-driYen gas in addition to the rlue gas which can be reactive wlth the gaseous pollutants in the flue gas. The particulate which constitutes the bed may be particulate in the flue gas or 2~ separate particulate such as aluminum oxide. Or it may be separate particulate sorbents which react with the pollutants or serve as a catalyst in pollutant reactions.
In the fluid-bed filter contactor, certain pollu-tants are converted into nontoxic particulate, by dry in~ec-tion of sorbents, ~iltered out by the filters and removedas ash. The treatment of these pollutants is a once-through operation. Other o~ the pollutants are converted into atmos-pheric gases which pass through the filters and are vented.
Specirically, the HC1 and HF are converted into salts Or 3 calcium, strontlum or sodium and o~ other alkaline or alkaline-earth elements. The SOx, SO2 and SO3 are converted into par-ticulate sulfates. The i30X, i.e., NO, NO2, N20, N204, is converted into atmospheric gases, nitrogen and oxygen, in a catalytic reaction. The carbon monoxide is converted into carbon dioxide, an atmospheric gas, by oxidation by the air ln the bed. The flyash is partlally agglomerated into lar~er particles and filtered out as ash. Since the flue gas in the 'I ` ~-`
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4 56,6~2 fluid-bed fllter contactor is at an elevated temperature, the reactions with the pollutants are accelerated.
Specifically, the lnvention comprehends the separation Or the pollutants in a fluid-bed filter contactor having high-temperature resistant ceramic filters by dr~
in~ection of HCl, HF, and desulfurizatlon sorbents and con-version of NOX by reductants operating in a catalytic re-action. The ceramic filters provide nearly complete parti-culate removal.
BRIEF DESCRIPTION OF THE DRAIrI~GS
For a better understanding Or this invention, both as to its organization and as to its operation, together with additional ob~ects and advan~ages thereof, reference is made to the following description taken in connectlon with the accompanying drawlngs, in which:
Figure 1 is a flow block diagram showing the practice of this invention and presenting as blocks typical apparatus used in the practice o~ thls invention;
Fig. 2 is a diagrar~matic view generally in longitu-dinal section showing a fluid-bed used in the practice o~
this invention;
Fig. 3 is a diagrammatic view in longitudinal section showin~ a bubblin~ fluid-bed used ln the practice o~ this invention;
Fig. 4 is a diagrammatic view in longitudinal section showing a turbulent fluid-bed used in the practice of this lnvention;
~i~. 5 is a dia~rammatic view in longitudinal section showing an entrained bed used in the practice of -this invention; and Fig. 6 is a rlow block dia~rammatic view showing specific practice of this lnvention.
DETAILED D~SCRIPTIOM OF IIIVENTIOII
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Fig. 1 shows incineration apparatus 10 in which the block 11 represents the storage and the ~eeding Or the MSW. The II~W is red, ror example, by a conveyor, into the burner 13 where it is burned~ producing flue gas and leavin~

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2~S~9~1 56,682 a residual ash which is removed from the burner. The burner is supplied wlth alr, usuall,y forced draft to erfectuate the combustion. The flue gas, the combustion ~roducts of the burner, heats a SteaM generator 15 which, as is customary in the incineration of MSI~, generates steam to drlve a tur-bine to produce power. Typically, the steam generator 15 includes a boller, a super-heater and an evaporator (all not shown). The combustion products pass from the steam genera-tor 15 into a fluid-bed fllter contactor 17. In ~ig. 1 the fluid-bed contactor 17 is shown connected between the steam generator and a heat exchan~er 19. In actual practice the contactor 17 may be interposed between any two Or the above three listed components, for example, between the boiler and the super-heater or between the super-heater and the evapora-tor. The flue gas which rlows into the contactor 17 is typi-cally at a tem~erature o~ about 90~F (483.5C). If the contactor 17 is interposed between the boiler and the super-heater, the flue gas tem~erature is about 1500F (815.5C).
In contactor 17 the pollutants are removed from the combustlon 2~ products or reduced to a small harmless content, The result-ing cleaned gas flows into the heat exhan~er 19 whére it is cooled and then flows lnto and out of a stack 21. Some heat derived from the heat exchan~er 19 may be su~plied to preheat the combustion air for the burner 13. There is provided facilities 23 for storing and feeding the sorbents, As shown in Fig. 1, the sorbents may be ln,~ected in one or more of a number of points in the system 10, namely, into the feed chan-nel 25, conducting the flue ~as from the burner 13 to the steam generator 15; between any two of the three components 3~ of the steam generator 15, but, in this caseS the fluid-bed contactor 17 must be downstream of the ~olnt of in,~ection;
into the feed channel 27 between the boiler and the bed 17, and/or dlrectly into the fluid-bed 17. There is also ~rovlded a facility 29 for storin~ and feeAin~ a reductant for N0x.
The reductant may be supplied directly or throu~h c~lannel 27 into the flu~d-bed 1,. T~nicall~, the cat~lvser for the re-duction is lncluded with the sorbents.

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~ 56~682 Instead of beln~ exhausted f'rom a stack, the cleaned flue ~as can drive a turbine (not shown), typically in a pressurized combustion plant. In this case, the heat exchanger 19 would be omitted. ~oth the steam turblne and the flue-gas turbine may be supplied or the boiler of the steam ~enerator 15 and its turblne may be omitted. The latter alternatlve has the advanta~e that the temperature Or the flue ~as is not reduced by the boiler.
The fluid-bed filter contactor 17 ma~ be of the type disclosed in Degnen et al., US 2,54R ~ 875 or Newby et al., 4,9?3,548. Specifically~ it includes a container 31 (Fig. 2) havinga plenum 33 separated from a lower chamber 35 of the container by a tube sheet 37. A plurality of ceramic candle filters 39 are suspended from the tube sheet 37 into chamber 35. The filters 39 are hollow and closed at the bottom. They open into the plenum 33. Above the lower wall of the chamber 35, there is a distributor screen 41. The ~aseous products of combustion (the flue gas) are injected by a drive (not shown), usually positive and/or negative pressure, in the plenum 45 below the screen 41 and distributed above the screen where they produce a pseudo-liquid fluid-bed 44 by reacting physically ~ith the particu-late sorbents or with particulate of a separate material in~rt to the pollutants such as aluminum oxide. The pollu-tants HCl, HF, Sx are converted into solid particulatewhich is captured by the pores in the external surface of the filters 39. The cleaned ~as, sans the particulate, passes through the filters into the plenum 33 whencè it is emitted to the stack 21 or to a turbine. The solid particu-3 late is moved upwardly and do~lnwardly and in en~a~ement withouter surfaces Or the filters 39 and scours the surfaces, removin~ the ca~tured particulate. The particulate which forms the bed typically has a cross dimension (diameter) of 0.25-inch (o.64 cm) or less. The solid ~articulates which ` 35 result from the reaction of the sorbents and the pollutants in the flue gas are discharged as ash, together with any unused sorbent-inert particles and the f`lyash, which is also captured by the filters 39 and by the solids in the fluld-bed.

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20~91 1 7 56,682 The N0x is reduced to nitrogen and oxygen by the reductant in the presence of a catalyser which is included in the sorbent. The nitrogen and oxygen pass through the candles and are released as clean gas. ~he carbon monoxide is oxidized to carbon dioxide, which is also passed throu~h the candles and released as clean gas. In the proper tem-perature range, typically 850C-1190C (1582F-2012F), the N0x may be decomposed by an ammonia reductant alone without a catalyst.
The sorbent particles mixing in the fluid-bed fllter contactor 17 protect the filter elements from stic~y particles and promotes the cleanin~ of the filter element surfaces. The agglomeration of any sticky ashparticles, fumes or tars in the combustion products, is also promoted by the highly mixed fluid-bed particles. The fluid-bed contactor environment may also provide catalytic conditions or improved contacting for the further combustion of carbon monoxide and flyash carbon. Ash particles that may accumu-late in specif`ic regions Or the fluid-bed contactor are drawn off for cooling, storage and disposal. Sorbent part-icles are drawn off at a sorbent-rich zone of the fluid-bed and are transported to separate or combined disposal with the ash.
The hydrochlor~c and hydrofluoric acid sorbents ~5 Or pri~ary interest are calclum-based materials (limestones, dolomites, quicklimes, hydrated li~es of various forms) and sodium carbonate materials available in various mineral forms. The sorbents perform effectively as either coarse partlcles or fine entrained particles in the temperature range of 600 to about 1100F (310.5C to 590.3C). Strontium carbonate is effective at temperatures in the range of 900F
to 1900 (480.3C to 1030.~C).
The sulfur sorbents of interest to the generic concept are:
Calcium hydrate sorbents in humidified flue gas at temperatures less than about 150C
(330.9F).

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2~9~1 8 56,682 Sodium-based sorbents for temperatures less than about 315C (599F).
CuO-based sorbents in the range Or 350C to 500C (662F to g320~).
Calcium hydrate sorbents in the range of 400C
to 550C (752F to 1030F).
Calcium based sorbents (limestones, dolomiteS, limes and hydrated limes) in the range of 700C
to 1100C (1292F to 2012F).
Strontium-based sorbents in the range of 980C
to 1300C (1796F to 2372F).
In the temperature range where CuO is suitable, ammonia may be inJected into the contactor to catalytically reduce NOX. The f~lters remove particulate material or aerosols generated by this process. In the temperature range of about 400C to 700C (752~F to 1292F), cyuranic acid (as developed by Sandia National Labs), or other reduc-tants, may be in~ected into the fluid-bed filter contactor to reduce NOX; the filters capture the solid reaction products.
At higher temperatures, 850C to 1100C (1562~ to 2nl2F), ammonia in~ected into the fluld-bed filter contactor reduces '~O via the Exxon noncatalytic process.
The followin~ Table I shows the various configura-tions and para~eters Or filter contactors which may be used in the practice o~ this invention.
TAB~E I
Confi~urations and Parameters of Fluid-Red Filter ~ontactors Fluid-bed re~imes:
3 - bubbling with coarse sorbent ~articles (~300 mi~rons .012-inch) shown in Fig. 3, - fully fluidized bed, - semi-fluidized bed, - hi~hly turbulent to dilute with small sorbent ~articles (~40 microns .016-inch) shown in Fig. 4, - fully fluidiæed bed, - semi-fluidized bed, - entrained with very fine sorbent particles ~20 microns .0008-inch) shown ln Fig. 5 ~4 Vessel orientation:
- vertical upward gas flow wlth bubblin~ and turbu-~
lent beds, - vertical upward, downward or horizontal gas flow with entrained beds.

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9 56,682 Filter element orientation:
- vertical, - horizontal.
Filter element parameters:
- length, 1 M - 1-1/2 M (3.28'-4.92'), - diameter~ 7.62 cm - 10.16 cm (3"-4"), - type (candle, bags, cross-flow), - spaclng and packing arrangement, 2 di~meters, - material, thiclcness and perm.eability, 0.5 cm (0.2"), - filter cleaninr technique, abrasive by particles, - ~ilter element manifold design, tub~ sheL-t.
~ed para~.eters-- sup~rficial gas velocity, 1 r1/sec (3.2~'/sec), - b~d depth, 2-3 ~l, - sorbent part~cle size distribution, ~o.64 cm (0.25"), - gas distributor desi~n, pipes, - ash and bed particle withdrawal design, pipe into dense area of bed.
The bubbling-bed filter contactor 46 shown in Fig.
3 includ~s a container 48, subdivided by a horizontal tube sheet 50 into an upper chamber or plenum 52 and a lower chamber 54. Ceramic filters 51 are suspended vertically from the tube sheet 50. The filters 51 are sealed through the tube sheet openin~ into plenum 52. rielow th~ filters 51 there is a screen or gas dlstributor 53. The holes in the distributor should be dimensioned to preclude plugging. It may also be neccessary to cool the distributor 53. Sorbents are supplied to the chamber 54 through conductor 55. The combustion products are conducted upwardly into the contactor 41 through the opening 57 and distributed in the chamber 54 by the distributor 53, producing a bubbling fluid-bed 59 between the distributor 53 and the tube sheet 50. Partlculate si e of the sorbents and the fluidizing velocity of the pro-ducts of combustion are selected so that the bed is a bubb-ling bed. The sorbents react with the gas-produclng parti-culate which is absorbed by the filters 51, resulting in clean gas which passes out through the opening 61. The ash is removed from the top part of bed 59 through conductor 63 and spent sorbent is removed from the lower part.o.f the bed throu~h conductor 65. Typically, the bed 59 has a relatively low depth, typically 1 to 2 meters (3.28-6.56 ft.).

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10 56,682 The bed mixing is relatively gentle. There ls segregation of the smaller and llghter ash particles which results in effective separation which allows the reinJection Or t~e fine sorbent particles in th~ gas.
The turbulent contactor 71 includes a container 73 having an opening 75 at the bottom and sealed at the top 77.
Chambers 79 are sealed through the side wall of the contain-er 73. Generally, horlzontal filters ~1 are sealed in oppositely arrayed columns through the chambers 79 openin~
into the chambers. The chambers79 are sealed at the bottom and open at the top. Sorbents are in~ected into the contain-er 73 through conductor 83. The combustion products are in~ected throu~h opening 75 producing opposite vertical beds 85. Ash is removed from the regions at the top through con-ductor 87 and spent sorbent from the region at the bottom through conductor 89. The clean gas is filtered into cham-bers 79 and is emitted from the open tops 90 of the chambers.
The turbulent reactor 71 generally operates at higher fluidizing velocities and with smaller bed particles than are used in the bubbling réactor 46. ~as and sollds rnixing in the bed are more vigorous, and the bed has lower density than in the bubblin~ reactor 46~ resulting in the use of deeper beds.
There are two types each of bubblin~ or turbulent fluid-beds. In one, a "fully" fluidized bed, one where surficient ~as velocity exists at the up~er bed surface to maintain fluidization of the particles at the upper bed surface, is produced by placing some filter surface above the bed as in .`~lewby so that all the gases are not removed 3 within the béd. In the other type, a "semi-fluidized" bed, where all the gas ~s removed lnternall~ to the bed and the top portlon Or the bed is nonfluldized, is produced by sub-merging all of the filter in the bed as in Degnen. This latter type is still free to expand, in contrast to the sèmi-fluidized beds dlscussed ln the open literature that have rlgid filter caps placed on top of the bed. In-bo~h cases, a very smalI-freeboard region is re~uired above the bed com-pared to thè large freeboard reglon normally needl~d above - .
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' . ': ` ' ': . ,i, 2~68~1 11 56,~2 fluidized beds, 3 to 5 meters, (9.84 to 16.40 ~t.) in most commercial ~luid-beds. The large rreeboard region in prlor-art beds is demanded because some particles in the bed are driven to substantial height.
The entrained contactor 91 lncludes a container 93 having an openin~ 95 at the top and taperlng at the bottom to form a hopper 97 throu~h which ash and spent sor-bent are removed. The sorbents and reductants are in~ected at the top through conductor 99 and the combustion products are transmitted downwardly through opening 95. An elongated chamber 101 is sealed through the wall of container 93 and sup~orts a row of horizontal ceramic filters 103, The fll-ters are sealed through the wall of the chamber 101 and are in communication of the chamber~ The filters extend sub-stantially across the container 93. The chaMber is closed at the top and open at the bottom.
The combustion products are introduced at a velo-city such as to produce a vertical entrained bed 105. The pollutants react with the sorbents and reductants, producing solids, ~hich adhere to the surface of the filters and are removed and are dischar~,ed throu~h hopper 97, and atmospheric ~ases which together with the clean gas pass throu~h the filters 103 and are vented through the open end 107 of the chamber 101. The sorbent particulate in the entrained con-?5 tactor which are agitated in the bed are not effective to scour the adhered cake from the filters 103. Cleanin~ ~ulses fro~. source 109 are necessar~ to dislodge the cake from the filters 103. Since the sorbent particles are small, the reactlons producing the cleanin~ are rapid, and the gas 3 velocities are very high compared to the velocities in the bubblin~ and turbulent reactors. Since se,~regatlon of ash and sorbent does not occur in the entrained reactor as it does in the bubblin~ and turbulent reactors, the sorbents are once through.
'35 Fi~. 6 shows speci~lc practice of thls invention in the temperature range be~ore the heat exchanger 19, some-times referred to as an "economizer", of about 400C to .
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12 56,6~2 550C (752F to 1022F). The lime hydrate 111 (or atmos-pheric pressure dolomitic hydrate or pressure hydrated dolomite), a particularly effectlve calcium-bascd sorbent, is in~ected as fine particles (-325 mesh) to convert simul-taneously the ~Cl, I~F and Sx into solid particulate and to filter out and remove this particulate as ash.
The Cu~O4 particulate 113 is in coarse rorm, typically -0.25-inch (-o.64 cm) and constitutes particulate which serves as the pseudo-liquid medium of the fluidized-bed and, in additlon, serves as the catalyst for the reduc-tion of NOX. ~hese coarse bed particles remain in the fluidized-bed ~!ith only limited replacement for long-time oeriods. The calcium hydrate sorbent and flyash are removed separately from the fluidized-bed by the natural segregation of these fine particles to the top of the fluidized-bed.
There~is a "drain'1 115 near the top Or the bed through which the fine particles flow like a liquid.
The followint~ Table II presents the factors that control the performance of this invention:
TABL~ II
Performance Factors 1. ~he MSW properties and the nature of the flyash particles produced.
2. The M~t! incinerator and operating conditions, ~5 and the temperature of the combustion products, the compo-sition of the combustion products, the dust loading, and the fluctuations in these conditions.
3. For retrofit appllcations, the avallable space.
4. rhe selected design and op~ratin~. conditions 3 of the emissions control device, particularl~ those influ-encing the preC~sure drop across the fluidized-bed and the pressure drop across the filter elements.
Ty~i~al operatin~ conditions and vessel size of the apparatus for practicinÆ this invention ls based on a gas pressure dro~ throu~h the fluid-bed and filter of about 40 inches (100 cm) of water, a plant size of 50 million Btu/hr, (V5.275 x 101 Joules/hr), a ceramic candl~ filter face velocity of 15 ft/min (4.6 M/min) in close-packed verti-cal or horizontal bundles. The vessel slze is from 2 to 3 ~1 .. ~. , : . :
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13 56,682 (6,56 to 9.84 ft.) in diameter, and 2 to 4 M (~.56 to 13.12 ft.) in height, respectively, with the CuO or CuSO4 catalyst o~ mean particle size about 400 mlcrons (.016-inch) ln dia-meter. The s~perficlal ~as velocities range from 1 to 3 M/s (3.3 to 9.8 ft/sec), respectively, and bed depths of 1 to 2.5 M(3.3 to 9.9 ft.), respectively. The performance estlmates for a typlcal Fig. 6 system are shown in Table III.
TABLE III
Performance Estimates 1. Partlculate control: ~ 99.9;~.
2, HCl/HF removal: ~ 90% potential.
3. Sx removal:~> 90% potential.
4. Sorbent consumption: Calcium-to-HCl molar feed ratio of about 1Ø

5. N0x reduction: Satisfy applicable emissions standards.

6. Am~onia consumption: Stoichiometric ratio about 1.2:1 ammonia to N0x.

7. Solid waste generation: Similar in nature but smaller quantity than in other dry, calcium-based or sodium-based sorbent in~ection schemes.
I~lhile preferred practice of this inYention has been disclosed herein, many modifications thereof are feas-ible. This invention is not to be restricted except insofar as is necessitated by the spirit of the prior art.

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Claims (17)

1. In the incinerating of municipal solid waste the method of separating pollutants from the products of combustion of the solid waste; said method comprising:
passing said products of combustion through a fluidized-bed filter contactor including filter means, introducing sorbents in reactive relationship with said products of combustion to convert certain of said pollutants into solid particulate, reacting reactants with said products of combustion to con-vert other of said products of combustion into atmospheric gases, passing the gas resulting from the reaction of the products of combustion with said sorbents and with said reactants through said filter means in said contactor to filter out substantially said particulate, venting the filtered gas and said atmospheric gas, and separating out the filtered solids as ash.

2. The method of claim 1 characterized by that the sorbents and the reactants are introduced into the products of combustion as said products pass to the fluid-bed filter contactor before said products of combustion enter said contactor.

3. The method of claim 1 characterized by that the sorbents are introduced directly into the fluid-bed filter contactor.

4. The method of claim 1 wherein the certain of the pollutants are selected from the group consisting of hydrochloric acid, hydrofluoric acid, and sulfur compounds and the other of said pollutants are selected from the group consisting of nitrogen oxides and carbon dioxide and 56,682 the sorbents react with the certain of said pollutants to produce solid salts, and the reactant includes a catalyst and a reduction agent and reacts to decompose the nitrogen oxides into nitrogen and oxygen and the carbon monoxide is reacted with air in the filter contactor to produce carbon dioxide.

5. The method of claim 4 characterized by the introduction into the products of combustion sorbents selected from the group consisting of calcium-based materials, sodium-based materials, strontium carbonate and copper oxide to convert the hydrochloric and hydrofluoric acids, calcium hydrate material, sodium-based material, copper oxide-based materials, and strontium-based material to convert the sulfur compounds and a reactant selected from the group consisting of cyuranic acid and ammonia to decompose the nitrogen oxides in a catalytic reaction with the ammonia.

6. The method of claim 5 wherein the copper oxide acts both as a sorbent in the conversion of the sulfur oxide and as a catalyst in the decomposition of nitrogen oxides in the reaction with ammonia.

7. The method of claim 5 including the step of adding copper sulfate to the fluid-bed filter contactor as the catalyst in the decomposition of nitrogen oxides in the reaction with ammonia.

8. The method of claim 11 characterized by the step of reacting the hydrochloric and hydrofluoric acids with sorbents selected from the group consisting of calcium-based materials and strontium carbonate to convert the said acids into solid particulate.

9. The method of claim 8 wherein the calcium-based materials are minerals selected from the group consisting of limestones, dolomites, quicklimes and hydrated limes.

10. The method of claim 1 wherein the incineration of the municipal solid waste produces flyash characterized by that the flyash is passed into the fluid-bed filter con-tactor with the products of combustion and is separated from the products of combustion in the contactor and deposited as ash with the filtered solids.

56,682

11. The method of claim 1 wherein copper sulfate particulate serves both as the pseudo-fluid particulate for the fluid-bed of the contactor and as the catalyst in the conversion of the other of the particulate into atmospheric gases.

12. The method of claim 4 wherein copper sulfate serves both as the catalyst and for the moving pseudo-fluid particulate of the fluidized-bed of the contactor.

13. The method of claim 7 wherein the copper sulfate is in particulate form and serves also as the parti-culate which constitutes the pseudo-liquid of the bed.

14. The method of claim 1 wherein the reaction of the other products of combustion to convert them into atmos-pheric gases is in the presence of a catalyst selected from the group consisting of copper oxide and copper sulfate.

15. The method of separating pollutants from the products of a combustion process that generates certain pollutants convertible into solid particulate by sorbents and at other of said pollutants are decomposible into atmos-pheric gas by a reductant in the presence of a catalyser;
the said method comprising: passing said products of com-bustion into a fluidized-bed filter contactor having a pseudo-liquid medium injecting into said contactor sorbents to convert said certain pollutants into solid particulate, introducing in said bed a catalyser and a reductant to decompose said other of said pollutants into atmospheric gases, filtering out the particulate and depositing it as ash and venting the gas from which the particulate has been filtered out together with said atmospheric gases; the said method being characterized by a fluidized-bed filter contactor whose pseudo-liquid medium comprises particulate composed of the catalyst.

16. The method of separating pollutants from the products of a combustion process that generates certain pollutants convertible into solid particulate by sorbents and at other of said pollutants are decomposible into atmos-pheric gas by a reductant in the presence of a catalyser;

17 56,682 the said method comprising: passing said products of combustion into a fluidized-bed filter contactor having a pseudo-liquid medium injecting into said contactor sorbents to convert said certain pollutants into solid particulate, introducing in said bed a catalyser and a reductant to decompose said other of said pollutants into atmospheric gases, filtering out the particulate and depositing it as ash and venting the gas from which the particulate has been filtered out together with said atmospheric gases; the said method being characterized by a fluidized-bed filter contac-tor whose pseudo-liquid medium comprises particulate composed of at least one of the sorbents.
17. The method of claim 15 characterized by that the other of the pollutants are oxides of nitrogen and the catalyser constituting the pseudo-liquid medium is selected from the group consisting of copper oxide and copper sulfate and the reductant is ammonia.