CN1091151A

CN1091151A - Partial oxidation of sewage sludge

Info

Publication number: CN1091151A
Application number: CN93101893A
Authority: CN
Inventors: M·R·卡恩; R·J·麦基翁
Original assignee: Texaco Development Corp
Current assignee: Texaco Development Corp
Priority date: 1993-02-20
Filing date: 1993-02-20
Publication date: 1994-08-24
Anticipated expiration: 2013-02-20
Also published as: CN1036933C

Abstract

A kind of method of handling toxicity mud.The mud of the about 0.5-20% of extruding solid content concentrates with high strength pressure subsequently in the belt pressure filter.Variation has taken place in the form of handling back mud, and its solid content is higher.With the mud heating of dehydration, flash distillation and/or centrifugal, but and have an appointment the 10-40% dewatered sludge and have the pump fuel slurry of higher calorific value to produce the about 50-70% of total solid content and to contain with postcombustion such as liquid hydrocarbon fuel and/or solid carbon fuel mix.In usual vaporizer, produce synthetic gas and/or combustible gas by partial oxidation.The mud that the by product steam of heat and the heat energy in the exhaust flow can be used to thermal dehydration.

Description

Partial oxidation of sewage sludge

The present invention relates to the partial oxidation process of the sewage sludge of environmentally safe.

Along with the progressively restriction of burying of refuse being filled out sealing, dumping at sea, the hi-tech incinerator is not general again in a lot of fields, and the public finds to dispose sewage sludge difficulty and expensive day by day.Term used herein " sewage sludge " is broadly defined as " aqueous waste ", refer in particular to the sewage sludge that contains a kind of following material at least of city domestic sewage discharge of pipes: human body waste (movement), domesti refuse is as Municipal waste and industrial waste and sewage such as street washing fluids.The total solids of the sewage that discharge in the city is about more than 1,000,000/500(ppm) usually, and the solid major part in the sewage is animal or vegetable substance, and " organic substance ", that is, and fat, carbohydrate, and protein.Except common inorganic salt common in water supply, also there are mineral or inorganicss such as husky and clay, if sewage sludge is from raw sewerage then may contain many known to the deleterious pathogenic agent of human health, in sewage, almost can find various microorganisms, the example bacterium, Protozoa, spore and born of the same parents.

The gasification of sewage sludge is described in No. 3,687,646, the United States Patent (USP) of incorporating this paper common transfer for referencial use into to some extent.At the common United States Patent (USP) of transferring the possession of the 4th, described in 933, No. 086 and do not heated and the aqueous slurry of sewage sludge is concentrated by shearing, at the common United States Patent (USP) of transferring the possession of the 4th, described in 983, No. 296 with the organic substance in the aqueous slurry of heating method sintering sewage sludge.Yet, these reference combine individually or with it and all theme of the present invention are not instructed or hint, promptly produce the sewage sludge that highly dewaters and heat-treat then by pressurization, flash distillation, mix with postcombustion, and with gas that contains free oxygen and temperature regulato importation oxidizing gas producer.At least the pyrogen exhaust flow that is contained a kind of following material: synthetic gas, reducing gas and inflammable gas.

The present invention relates to the partial oxidation process of disposal sewage sludge free from environmental pollution, this method comprises:

(1) concentrate contain about 0.5～20%(weight meter) the solid sewage sludge, produce the 15～65%(weight meter of having an appointment that contains of highly dehydration) solid mud and from the mud of described dehydration, isolate the water of surplus:

(2) in reaction zone, in about 130 to 200 temperature range, no air stopped about 1 to 20 minute down and barometric point down the mud that in (1), obtains of heating, in about 300 to 650 temperature range, stopped about 5 to 120 minutes under the no air and be equal to or higher than under the pressure of the water vapor pressure under the thermal treatment temp and heat subsequently to produce pumpable sewage sludge aqueous slurry;

(3) in flash zone, the pressure of the sewage sludge aqueous slurry that will make from (2) (with corresponding temperature) is reduced to the certain pressure scope, promptly about atmosphere is pressed onto under about 200 to 400 temperature, the pressure range that the saturated steam of this flash zone is depressed, thereby evaporation and isolate abundant water from described sewage sludge, to produce the sewage slurry of pumpable dehydration, its range of solid content about 30 is to 70%(weight meter), and has a more high heating value (HHV), about 5,000 to 9,500BTU/LB;

The dehydration sewage sludge mud and the postcombustion that (4) will obtain from (3) mixes mutually so that pumpable about 50 to the 70%(weight of total solid content that have to be provided) and contain 10 to the 40%(weight meters of having an appointment) dehydration muddy water mud, and has a more slurry of high heating value, about 5,000 to 14,000BTU/LB; With,

(5) under about 1800-3000 and 1-30 normal atmosphere, in the producer gas generator reaction zone, with the air-flow that contains free oxygen and temperature regulato to from (4) but the pumping mud that obtains carry out partial oxidation, produce the undressed air-flow of the heat that contains following a kind of gas at least, synthetic gas, reducing gas and inflammable gas.

Another embodiment of the partial oxidation process of sewage sludge comprises:

(1) contain about 0.5 to 20%(weight meter with usual continuous band pressure filter extruding is described) the solid sewage sludge, make it concentrated, optionally on the continuous high strength pressing machine of routine, push subsequently to produce containing of highly dehydration and have an appointment 15 to 65%(weight) the solid sewage sludge, from described dehydration sewage sludge, isolate excessive water;

(2) in temperature range about 130 °F to 260 °F, normal atmosphere and no air exist down, the sewage sludge that obtains in the heating (1) in reaction zone is about 1 to 20 minute, then in the presence of about 300 to 650 the no air of temperature range, heated 5 to 120 minutes and be equal to or higher than the pumpable sewage sludge aqueous slurry of the following production of pressure condition of the water vapor pressure under the thermal treatment temp approximately; With in described heat-treatment zone, described dehydration sewage sludge and the indirect contact of inflammable gas hot gas flow; Produce wherein said inflammable gas in this method downstream;

(3) in flash zone, the pressure of the sewage sludge aqueous slurry that will make from (2) and relevant temperature reduce, the Saturated water vapor pressure when pressure range after the reduction is about 200 to 400 for about atmosphere is pressed onto this flash zone temperature, thereby from described sewage sludge the evaporation and isolate enough water to produce pumpable dehydration sewage sludge slurry, its range of solid content about 30 is to 70(weight) %, and has more high heating value (HHV), about 5000 to 9500BTU/LB;

(4) passage by the hyperchannel annular burner will be from (3) but the pumping slurry of the sewage sludge of the dehydration that obtains be input to the reaction zone of partial oxidation gas generator, contain the gas stream of free oxygen with other passage input of burner simultaneously and the fuel that replenishes separately selected flows from one group of fuel being made of the water slurry and their mixture of liquid hydrocarbon fuel, solid carbon-containing fuel, solid carbon-containing fuel;

(5) in the partial oxidation reaction district described in (4), under about 1800 to 3000 and about 1-30 normal atmosphere, make described material reaction contain a kind of untreated exhaust flow of heat of following gas at least with generation; Synthetic gas, reducing gas and combustible gas;

(6) cooling, purification and purifying derive from the combustible gas stream of (5); With

(7) in internal combustion turbine, burn derive from (6) thus described combustible gas produce mechanical energy and combustion gas, and make the exhaust flow that carries out heat exchange with indirect mode and described dewatered sludge that heat-treatment zone in (3) that provided as (2) is provided.

Can understand the present invention better with reference to the accompanying drawings, accompanying drawing only is schematically illustrating of present method preferred embodiment.

It is free from environmental pollution to put sanitary sewage mud with method processing of the present invention.In this method, produce the highly mud of dehydration by extruding, carry out heat treated, flash distillation then, mix with postcombustion, in the partial oxidation gas reactor, react with the gas and the temperature regulation that contain free oxygen, produce the undressed hot waste gas stream that contains a kind of following gas at least: synthetic gas, reducing gas and combustible gas.

The carbonaceous fuel that replenishes and dehydration sewage sludge (weight meter) portion rate are respectively about 5-7 than for example about 6: 1 of 0.5-2.Dehydration sewage sludge and carbonaceous fuel that replenishes and the gas that contains free oxygen carry out partial oxidation reaction in free-pouring on-catalytic gas reactor.Poison sewage mud can be disposed safely and free from environmental pollution with method of the present invention, in addition, except that by product air-flow and hot water, a kind of useful and nontoxic synthetic gas, reducing gas and combustible gas can also be produced at least.Isolate free of contamination ash and slag from gas stream, ash and slag can be used as the filler of roadbed and can be used to make cement block.Method of the present invention in addition can be carried more substantial sewage sludge in the partial oxidation gasifier, like this, the energy that the sewage sludge of processing unit mass needs still less.This method has following advantage:

(a) poison sewage or industrial sludge can be handled and free from environmental pollution, and clean combustible gas and/or synthetic gas can be produced.

(b) the by product combustible gas that produces from the partial oxidation gasifier can be used as the fuel of turbo-generator, the by product synthetic gas can be used for the catalysis of organic chemicals such as methyl alcohol synthetic in.

(c) present method has been utilized the used heat that obtains from combustible gas.Usually can not change into to very economical energy cycle because this used heat temperature is too low, and can only be excreted in the atmosphere.

(d) slag that in the partial oxidation of the mixture of mud and solid carbon fuel, produces do not contain pollutent, and with being safe.This slag also can not leaching in addition.

(e) present method has higher thermo-efficiency, and interior generation steam that produces in waste heat boiler and/or the water that produces in flash zone can be used to the thermal dehydration sewage sludge, and steam also can be used as the working medium of expansion of vapo(u)r turbine.Typical combustiblematerials results of elemental analyses is shown in the table I in the sewage sludge, and the results of elemental analyses of the representational noncombustibles material of inert is shown in the table II in the mud.Dried sewage sludge has more high heating value (BTU/Lb), about 3000 to 7000.

The table I

The typical element analysis of sewage sludge

Element % (weight meter)

Carbon 29-50

Hydrogen 4-6

Nitrogen 4-5

Oxygen 12-30

Sulphur 1-3

Ash 20-46

The table II

The analysis of inertia typical case noncombustibles material in the sewage sludge

The dried solid of element M G/KG

Total sodium 1.515

Water-soluble sodium (mg/l) 83

Total potassium 800

Water-soluble potassium (mg/l) 53

Arsenic 4.58

Beryllium 0.38

Cadmium 3.27

Chromium 244

Copper 289

Iron 150

Plumbous 147

Zinc 468

Nickel 63

Mercury 0.68

Gasification wastewater mud whether economy largely depends on the concentration that the mud that is subjected to from the Residential areas that produces mud is toppled over expense and sent to the sewage sludge the pumpable slurry of gasifier.Contain 20 to the 50(weight of having an appointment) sewage sludge that contains of the mixture of % solid dehydration sewage and solid carbonaceous fuel such as coal enough with burnt economically usually too sticking can not pumping.The present invention has overcome this problem and other problem.

Treatment step and equipment with routine can obtain sewage sludge from raw waste water, for example, the sewage of discharging in the urban sewage pipe is removed massive stone by grizzly, and timber, metal and other may block pipeline or damage the refuse of the pump housing.In settling pit, big and heavy fireproof inorganic thing such as gravel, slag and sand are settled down then, sewage is separated into contains aqueous suspension sewage sludge and liquid subsequently.Available any method that is suitable for separate solid and liquid concentrates sewage, and for example, gravitational settling filters, and is centrifugal, hydrocyclone or its combination.For example, preferred pre-treatment step is to be incorporated into through settling pit screening overflow (as at Perry ' s Chemical Engineers ' Handlook, McGrow-Hill, the 4th edition, 1963, shown in the 19th～50 page) continuously in the primary settling groove such as settling pond, about 1 to 24 hour of residence time in subsider was exactly to produce the pumpable aqueous slurry of preliminary sludge, its solid content about 0.5 is to 20(weight) %, the primary settling groove also can be used as storage tank so that the discontinuity of sewage composition is overcome, and also can use independent storagetank.For example, as being input in the storagetank and with elementary sewage sludge, mixes the pumpable aqueous slurry of second stage sewage sludge.About 1 to the 10(weight of the range of solid content of second stage sewage sludge) % and derive from overflow liquid in the above-mentioned primary settling groove, handle overflow liquid in a usual manner producing second stage sewage sludge, and reduce BOD and organic solid content and isolated waste water from the sewage sludge of the second stage is carried out purifying and demineralization.According to the end-use of isolated water, the processing of the overflow liquid in the primary settling groove comprises combination any or preferred the following step: regulate PH; Reduce organic solid and BOD to about 20ppm or lower, preferred aeration biochemical is handled; Clarification is optionally condensed; Filtration or centrifugal; Demineralization materialization; Activated carbon treatment; For example control bacterium with sterilization with chlorization.Too high as the acid of waste water or alkalescence, can be neutralized and PH is adjusted to about 6 to 9.Preferably use anaerobion and aerobic bioremediation to reduce economically because the pollution of the caused oxygen consumption bacterium of waste water of exhausting low-concentration Organic pollutants.Suitable conventional biological treatment comprises active sludge equipment, aerated stabilization basin and trickling filter.The United States Patent (USP) 3,687,646 of common transfer is seen in other description; 4,933,086; With 4,983,296, it is for referencial use that these files are incorporated this specification sheets into.

The water that purifying is crossed can be used in this law subsequent technique.For example, the water crossed of purifying can be in quench tank with direct contact or in waste heat boiler with the mode of indirect heat exchange refrigerant as the product gas that obtains in the partial oxidation gasifier.After removing the dissolved solid, can produce the by product steam, hot water or steam can be used to the inventive method in other air-flow carry out indirect heat exchange.For example, be used for preheating also in view of the above the mode that further describes is condensed sewage sludge water in suspension liquid.Excessive water can be discharged from system or is used for industry from the outside.

Containing the underflow mud of discharging from the primary settling groove of elementary sewage sludge or the underflow mud of discharging from storagetank that contains elementary sewage sludge is a mixture, the total sewage sludge of 0-50%(that is about B-grade sewage mud by weight is basic shape), fluid layer mud under this is further dewatered to produce spissated water in suspension liquid.In a step of present method, to sewage sludge with about 0.5 to the 20 weight % of solids content scope preferably with the press filtration of continuous band pressure filter to make it concentrated, produce the sewage sludge that highly dewaters, it is because of about 15 to the 65 weight % of content range, 30 to 40 weight % according to appointment, such as 35 weight %.Make us unexpectedly, this sewage sludge is behind this mechanical treatment, and variation has taken place its form, and for example, combination water has been disengaged and the mud that forms also is best.But can obtain to contain greater concn solid pumping mud with similar mechanical dewatering equipment.With the continuous band pressure filter press filtration of routine, at this moment sewage sludge by between carrying roller or pass through on the carrying roller two the motion belts between press filtration.The surface pressure about 20 that imposes on the sewage sludge arrives the 200psi(pound per square inch, about 1/2 to 60 minute of time length, 1 to 30 minute according to appointment, 3 minutes according to appointment, therefore promptly squeezes out liquid water from sewage sludge.For example, u s company (Texas) at ambient temperature, the about 20psi continuous filter press of the surface pressure of executing (CPF) has generation the press cake of about 20 to the 50 weight % of solids content for Andritz Co., Arlington.After optionally unloading from CPF, the said firm (Andritz Co.) is further dewatered to cake of press.The press filtration of the continuous skin formula of high strength pressure filter, impose surface pressure and similar operations time about 200psi, can obtain having the press cake of about 25 to the 55 weight % of solids content according to appointment in 1/2 to 60 minute, optionally, when carrying out the extruding of described high strength, also this mud can be heated to about 100 ℃ to 140 ℃ with further dehydration.Further dewater as need, the inorganic filter additive of available routine (5-30 weight %) for example, has particle diameter less than about 2mm, according to appointment the CaCo of 1mm ₃Or coal, exist or do not exist and handle the press cake that derives from continuous filter press under the steam, in a case study on implementation, flocculating aids is selected from ickings, and refinery coke breeze and their mixture are in another case study on implementation, flocculating aids chosen from Fe compound, calcium cpd, silicon compound and their mixture.Can be in view of the above with the solid content of the press cake that from the high strength pressure filter, obtains and then be increased to about 35 to 65 weight %.In a case study on implementation, continuous band pressure filter and centrifugal combining are concentrated mud.

The next step of present method is, sewage sludge to highly dehydration is heat-treated, in about 130 to 200 temperature range, no air exists down, under normal atmosphere, about 1 to 20 minute, subsequently in about 350 to 650 temperature range, no air existence continued about 5 to 120 minutes down and is equal to or higher than under the pressure of the vapour pressure of water under this thermal treatment temp, but the sewage sludge of height dehydration is carried out preheating to produce pumping sewage sludge aqueous slurry.Therefore, can be in autoclave with the mode thermal dehydration sewage sludge of direct or indirect heat exchange, for example, steam or part refrigerative synthetic gas sewage sludge that present method downstream of being passed through produces carry out direct or indirect heat exchange, foregoingly can cause the decarboxylation and the dehydrogenation of mud, and then produce about 5 to the 20 microns mud of particle size range at about 300 to 650 temperature range thermal treatment dehydration sewage sludge.Thereby produce pumpable aqueous slurry with more highly filled sewage sludge.That discharges from reactor such as autoclave contains CO ₂, H ₂O, H ₂The waste gas of S and CPS etc. is admitted to conventional smell control unit or sterilizating area, thereby handles toxic gas safely, and don't contaminate environment.

In a case study on implementation, can remove the hot water of about 300 to 500 cleaning of temperature range from the bottom of reactor, and it is used for and the sewage sludge sent in the reactor carries out indirect heat exchange.

The pumpable aqueous slurry that will obtain from reactor is input in the flash zone, the pressure of flash zone be reduced to about barometric point to this district 200 full pressure ranges of closing vapor pressure to 400 following water, thereby evaporation and isolate enough water in the sewage sludge in the flash zone, produce pumpable dehydration sewage sludge, slurry with about 30 to the 70 weight % of range of solid content.The scope of the more high heating value (HHV) of this dehydration sewage sludge is about 5,000 to 9,500BTU/Lb, according to appointment 5,500 to 7,000BTU/Lb such as about 6,500BTU/Lb.Biao Shi whole more high heating value is with the calculating of butt material herein.Optionally, isolated at least a portion water is under about 200 to 500 temperature in the flash zone, and the same sewage sludge in autoclave carries out direct or indirect heat exchange, and then has improved the thermo-efficiency of present method.Selectively, can carry out centrifugation step after the flash distillation step anhydrates to remove.In another case study on implementation, but be cooled to about room temperature to 200 and substitute the flash distillation step with the centrifugal method of routine is isolated enough water from mud step with the pumping aqueous slurry of the heat that will from reactor, obtain.Thereby obtain the dehydration sewage sludge slurry of about 30 to the 70 weight % of pumpable solids content, more high heating value (HHV) scope of this dehydration sewage sludge is about 5,000 to 9,500BTU/Lb, according to appointment 5,500 to 7,000BTU/Lb.

To have HHV scope about 6,000 to 18, the postcombustion of 000BTU/Lb mixes to produce the slurry of pumpable dehydration sewage sludge and postcombustion mutually with the dehydration sewage sludge that derives from flash zone, and this pumpable slurry contains the sewage sludge of the 10-40 weight % that has an appointment and has about 50 to the 70 weight % of total solids level, 50 to 65 weight % and HHV scope about 5 according to appointment, 000 to 14,000BTU/Lb, according to appointment 7,000 to 12,000BTU/Lb, for example 9,000BTU/Lb.The about 5-7 of scope is than 0.5-2 separately for the carbonaceous fuel that replenishes and the ratio of described dehydration sewage sludge parts by weight, and 6 parts of heavy postcombustions are than the described dehydration sewage sludge of 1 part of weight according to appointment.Selectively, the water of condensation that obtains from flasher can be used to prepare the grout of solid carbon fuel, and these grouts then mix mutually with described postcombustion.

When the water in suspension liquid that solid content is surpassed the common sludge of about 20 weight % mixes with coal, produce very sticking slurry.Therefore, form the moisture sewage sludge coal slurry material of about 50 to the 60 weight % of range of solid content when the Portland cement slurry is mixed with coal particle or coal water slurry, the slurry of formation is too sticking at all can't pumping.Yet the present invention has overcome this deficiency, uses the present invention, but can produce moisture sewage sludge slurry of pumping about 50 to the 70 weight % of total solid content, that can send into part oxic gas device and postcombustion.About 10 to the 30 weight % of scope of the amount of solid that sewage sludge provides in total fuel of carrying, 20 to 30 weight % according to appointment.All the other solids are that postcombustion provides in total fuel in sending into gasifier.This point has superiority economically because the benefit that in the pneumatolysis of subsequently mud, is produced be by the sewage sludge postcombustion of sending in the part oxidation reaction zone in the percentage of sewage sludge determined.This use " and/or " normal implication, for example, it may represent that postcombustion is a kind of material A that is selected from, the material of the mixture of material B and they.

With the postcombustion of height dewatered sludge by partial oxidation gasification can be to have more high heating value (HHV) at least about 14, the 000BTU/Lb(butt) solid carbon fuel or (more high heating value) HHV be at least about 10, the liquid hydrocarbon fuel of 000BTU/Lb.In a case study on implementation, postcombustion is the carburet hydrogen class A fuel A, inflammable gas for example, the about 75BTU of the every at least standard cubic foot of the HHV of this gas.Preferably, solid carbon fuel is the aqueous slurry of coal and/or petroleum coke, and coal and/or petroleum coke can be replaced by the particle diameter of sieve (ASTM E11 Standard Sieve Designation1.40mm), available #14 to 100 weight % by pregrounding.The term coal comprises hard coal, bituminous coal, subbituminous coal, the coke that makes from coal, brown coal, the residuum that obtains on from gelatin liquefaction and their mixture.Petroleum coke by the delay of routine or the fluid pyrogenic process make, after the height dewatered sludge that makes at this mixes, but the dehydration sewage sludge that forms and about 50 to the 70 weight % of pumping aqueous slurry solid content of solid carbon fuel and tool be high heating value more, (HHV) at least about 5, the 000BTU/Lb(butt), about 500 to 3,000 centipoises of range of viscosities.

The mud of the height dehydration that from flasher, obtains with high pressure sewage sludge feed pump delivery and in-line or in mixing vessel with moisture coal that from the coal slurry fresh feed pump, obtains and/or the mixing mutually of petroleum coke slurry stream, obtain more high heating value (HHV) (at least 5, but the stream of pump fuel 000BTU/lb), this fuel stream then is transported in the partial oxidation reaction district of gasifier.Another embodiment is that the sludge stream that the height that obtains from flasher dewaters is failed with high pressure mud transferpump and burner tip and postcombustion and the mixed gases that contains free oxygen gasifier.For example, feeding contains the gas of free oxygen and the isolating air-flow of water coal and/or petroleum coke on the isolating passage in burner.As a result, mixed flow carries out partial oxidation reaction in the reaction zone of gasifier.This method can make the considerable material in the mud, and gasification and still need handle pumpable mud is so more mud input gasifier is handled the required energy of the mud of unit mass then still less.Further, the gasifier burner atomizes fuel stream fully and has avoided the problem of any flame stability.

To and contain the clog-free dirty vertical refractory-lined steel wall pressure force container of fuel stream input unrestricted flow of the air-flow of free oxygen as the aqueous slurry of sewage sludge and coal and/or petroleum coke, in this container, carry out partial oxidation reaction, the United States Patent (USP) the 3rd of incorporating this paper common transfer for referencial use into, shown in 544,291 and described a kind of typical producer gas generator.

As be incorporated in annular two or the three stream annular burners shown in No. the 3rd, 847,564, accompanying drawing for referencial use and the common United States Patent (USP) of transferring the possession of herein and can be used to feedstream is input in the partial oxidation gas generator.For example, according to United States Patent (USP) the 3rd, 847, No. 564 introductions, the gases that can will contain free oxygen simultaneously by the center conduit 18 and the logical birth 14 of outer ring-type of described burner import, the gas that contains free oxygen is selected from pure substantially oxygen and for example is higher than the 95(mole) %O ₂Oxygen-rich air as, be higher than the 21(mole) %O ₂, and air, supply with the gas that contains free oxygen in about 100 to 1000 temperature range; Under the temperature of about room temperature to 650, feed sewage sludges and as the aqueous slurry of the solid carbon fuel of coal and/or petroleum coke by more intermediate annular passage 16.

Top inlet by the on-catalytic synthetic gas generator inserts the sets of burners component downwards, and burner extends along the central longitudinal axis of producer gas generator, and this producer has fuel, contains the gas of free oxygen and as H ₂O, CO ₂, N ₂Deng the multiphase mixture of temperature regulato directly enter the discharge end of reaction zone.Feedstream collides mutually near the burner top, so be atomized and thorough mixing.

The careful relative proportion of adjusting fuel, water and oxygen in the feedstream of sending into producer gas generator can make the most of carbon in the fuel, for example, up to about 90% or the carbon of higher (weight meter) change into carbonic acid gas; And the temperature that keeps the spontaneous reaction district is at about 1800 °F to 3500 °F, in the gasifier preferably temperature range be about 2200 °F to 2800 °F, to produce the stove quarrel of melting.In addition, H in feedstream ₂O to the weight ratio of carbon about 0.2 to 3.0, according to appointment 1.0 to 2.0.Free oxygen is about 0.8 to 1.4 to the atomic ratio of carbon in feedstream, according to appointment 1.0 to 1.2.More advantageously, when the amount of fixed oxygen in the sewage sludge is high, the consumption of free oxygen then will reduce.

About 1 to 10 second of residence time scope in reaction zone is preferably about 2 to 8 seconds, as in producer gas generator, import be pure basically oxygen the time, the waste gas of from producer gas generator, discharging (mole %, butt) composed as follows: H ₂10 to 60, CO20 to 60.CO ₂5 to 40, CH ₄0.01 to 5, H ₂S+COS O to 5, N ₂O to 5, and ArO to 1.5.Contain unconverted carbon, ash in the exhaust flow, or the stove of fusing quarrel, different according to forming with purposes, and exhaust flow is called synthetic gas, reducing gas, or combustible gas.The ash content of coal is higher, for example about 10 to 30 weight %, and surprisingly, coal ash has sealed the noncombustibles material in the mud, and this is a kind of useful record, and the material of sealing flows out from the reaction zone of producer gas generator as the stove quarrel of inertia fusing in fact.In the various case study on implementation of this paper, available said solid carbon fuel is with by water, liquid hydrocarbon, and the liquid of selecting in one group of compound that liquid hydrocarbon containing fuels and its mixture are formed provides as the form of the pumpable coal of medium and/or petroleum coke mud.

The used heat air-flow of synthetic gas generator reaction zone in quench tank by the direct quenching of water, or the form by indirect heat exchange for example with the waste heat boiler that produces steam in the feedwater indirect heat exchange and be cooled to rapidly below the temperature of reaction, to about 250 °F to 700 °F.The exhaust flow of available ordinary method purification and purifying gasifier.For example, referring to No. the 4th, 052,176, the common United States Patent (USP) of transferring the possession of, from the exhaust flow of conventional gas zone purification, remove H in this patent ₂S, COS and CO ₂Method can be used as reference of the present invention.

In a case study on implementation, in the partial oxidation reaction district, import additive, to promote sealing and removal to the stove quarrel of the inertia fusing that is present in the noncombustibles material in sewage sludge and the solid carbon fuel with other raw material.Additive is selected from iron compound, and calcareous material, silicon-containing material and their mixture for the noncombustibles material of every part of weight, add 0.1 to 10 part approximately and re-add agent in gasifier.Iron-containing additive can be selected from for example iron, ferric oxide, iron carbonate, iron nitrate and their mixture; Additives containing calcium is selected from for example calcium oxide, calcium hydroxide, lime carbonate, nitrocalcite, Calcium Fluoride (Fluorspan), calcium phosphate, lime borate and their mixture; Silicon-containing additive is selected from for example silicon-dioxide, quartz, silicate, volcanic ash and their mixture.

The synthetic gas of the purification that present method produces can be used for the catalysis of organic chemical industry's product synthetic in.For example, by method synthesizing methanol and the acetate described in No. the 4th, 081,253, the United States Patent (USP) that is incorporated in this paper common transfer for referencial use.

The inflammable gas that present method produces can burn in the combustion chamber of internal combustion turbine, and the stack gas that produces in the combustion chamber of internal combustion turbine can be used as the working medium of the expansion gas-turbine that drives generator.The heat energy of gas-turbine waste gas can be reclaimed in the recovery of heat steam generator, for example, make oiler feed and gas-turbine waste gas carry out heat exchange in the indirect heat exchange mode, can produce low-heat, moderate fever with the superheated steam flow to be used for present method.

The gas-turbine waste gas that also is known as stack gas contains CO basically ₂, N ₂And H ₂The U of O and about 1-10 volume % ₂In a case study on implementation, stack gas is used for the sewage sludge of thermal treatment dehydration, and the input temp scope contacts with the sewage sludge that highly dewaters indirectly to the stack gas of 300 ° of G for about 150 °F in autoclave.In autoclave with about 350 to 650 temperature, no air exists down and under about 1 to 45 minute of the residence time condition heat-treats, pressure in the reactor is the water vapor pressure that is equal to or higher than under thermal treatment temp, produces the pumpable sewage sludge aqueous slurry because of the about 20-50 weight of content range %.

In a case study on implementation, the combustible gas that a part produces in partial oxidation gas generator is as the postcombustion in the partial oxidation gas generator.For example, directly feed the dehydration sewage sludge that obtains the flasher from a passage of annular burner, burner is contained in the ingress, top of producer gas generator, feeds inflammable gas from another passage of burner; With, feed the gas that contains free oxygen from another or two passages of burner.For example, in burner, feed the air-flow that contains free oxygen, feed pumpable dehydration sewage sludge aqueous slurry from middle circular channel, feed combustible gas stream from the outer ring passage from center conduit with center conduit and two annular concentric passages.

Relate to the method that in boiler or incinerator perfect combustion sewage sludge prepares fuel in another embodiment, this method comprises:

(1) concentrates with the band platen press and contain about 0.5～20 weight solid sewage sludge and contain the sewage sludge of about 15～65 weight % solid height dehydration, from described dewatered sludge, isolate excessive water with generation;

(2) under about 130～200 of temperature range, the existence of no air, about 1～20 minute of the residence time and barometric point, the sewage sludge that heating obtains from (1) in reaction zone, then exist at about 300～650 of temperature range, no air, about 5～120 minutes of residence time and being equal to or higher than under the pressure of vapour pressure of the water under this thermal treatment temp heats, to produce pumpable dirty aqueous slurry;

(3) in flash zone, the pressure and the relevant temperature of the mud aqueous slurry that will make from (2) are reduced to the pressure range that about atmosphere is pressed onto water saturation water vapor pressure under described flash zone temperature, about 200～400 of the temperature range of described flash zone, thereby from described mud evaporation with separate enough water to produce about 30～70 weight % of pumpable range of solid content and high heating value (HHV) scope about 5 more, 000～9, the dewatered sludge aqueous slurry of 500BTU/Lb; With

(4) the dewatered sludge slurry that will obtain from (3) mixes with postcombustion and forms the about 50-70 weight of total solid content scope % and contain the 10-40 weight % dewatered sludge of having an appointment that to reach more the high heating value scope about 5,000-14, but the pump fuel slurry of 000BTU/Lb.

Accompanying drawing with reference to the preferred case study on implementation of explanation the present invention can more completely be understood the present invention, but the present invention is not limited to described ad hoc approach or raw material.

The about 0.5-20 weight of range of solid content in pipeline 1 %, 15 weight % according to appointment, with the about room temperature to 212 of temperature range, according to appointment 70 municipal sludge at random with derive from pipeline 2 in the solid carbon fuel for example pulverized of filtration adjuvant mix mutually, by pipeline 3 mixture is input to belt filter press 4, the water of emitting from pipeline 5 is sent to conventional water purification system, sending highly by pipeline 6 from belt filter 4, the mud of the about 20-50 weight of the range of solid content % of dehydration also can pass through pipeline 7, valve 8 and pipeline 9 and 10 are sent it into reactor 15, and the steam that produces in present method downstream of waste heat boiler 16 is sent with direct or indirect heat exchange method by pipeline 17 provides the heating sewage sludge required heat in reactor 15.In another case study on implementation, dewatered sludge in the pipeline 6 is by pipeline 19, valve 20 and pipeline 21 are delivered to high strength extrusion machine 22, once push again at this, remove by pipeline 23 and to anhydrate and water is delivered in the conventional purifier apparatus, send into reactor 15 by the height dewatered sludge that pipeline 25 is emitted from high strength pressure filter 22 from pipeline 10, highly Tuo Shui mud is in reactor 15, with temperature range about 130 °F-650 °F, in the presence of no air, to be equal to or higher than under the pressure of the water vapor pressure under this temperature of reactor, heated about 6-140 minute, promptly produce pumpable mud aqueous slurry.Also available another kind of method provides heat to reactor 15, promptly carrying out indirect heat exchange by pipeline 36 combustible gases that send, that produce in the dirty expansion gas-turbine 35 of the inventive method provides, and the tail gas that produces from reactor 15 is sent into conventional gas purification unit (not shown) by pipeline 26.

The heat treated mud of emitting from reactor 15 is through pipeline 18 input flash zone 38, in flash zone 38 pressure of the aqueous slurry of mud reduced to about atmosphere and is pressed onto in the pressure range of distinguishing the Saturated water vapor pressure under 38 temperature.By pipeline 39 evaporation with remove enough water, these water are used in the aqueous slurry of preparation solid postcombustion in the mixing tank 41, the dewatered sludge slurry of emitting the about 30-50 weight of pumpable range of solid content % by pipeline 40.

But the additional carbonaceous fuel of sending from pipeline 42 mixes mutually with the dewatered sludge aqueous slurry of sending from pipeline 40 mixing tank 41 and produces the pump fuel that HHV has increased.For example, liquid hydrocarbon fuel or the solid carbon water-in-fuel mud sent from pipeline 42 mix mutually with the mud of the height dehydration of sending from pipeline 40 mixing tank 41, but the HHV about 5 of the pumping mixture that forms, 000 to 14,000BTU/Lb, this mixture is input in the conventional refractory-lined non-catalytic partial oxidation synthetic gas generator 49 of unrestricted flow by the outer ring-like passage 51 of pipeline 50 and burner 52, the about room temperature to 1 of temperature range in the pipeline 53,000 gas that contains free oxygen such as air feed center conduit 54, and burner 52 vertically is installed on central authorities mouthful 55 places on gasifier 49 tops.

Contain H ₂, CO, CO ₂, H ₂O, N ₂And CH ₄The untreated waste gas of heat emit from gasifier 49 bottoms by pipeline 56 and waste heat boiler (WHB) 16, be cooled to about 600 °F～2600 °F, the also available another kind of method cooling of this waste gas, i.e. the exhaust flow (not shown) of water quenching heat.Oiler feed in pipeline 37 changes into steam and emits by pipeline 17 in 16, in water and the cleaning by solvent in the gas sweetening of routine and zone purification 61 of the former air-flow of part refrigerative in pipeline 60 at 16 tops, according to operational condition and raw material, by pipeline 62, valve 63 and pipeline 64 are removed synthetic gas from 61 districts, also can pass through pipeline 65,66, valve 67 and pipeline 64 are removed combustible gas from 61 districts, to be used in the about 180-350BTU/SCF of thermal capacity of other local this combustible gas of present method, this combustible gas can be through pipeline 70, and valve 71 and pipeline 72 are sent in the burner 73.Contain combustible gas perfect combustion burner 73 of the air of sending from pipeline 74, stack gas is sent in the expansion gas-turbine 35 that drives generator 76 by pipeline 75.In a case study on implementation, also the heat treated dewatered sludge in the pipeline 40 is directly sent into first circular channel of burner, this burner has a center conduit and two annular concentric passages.Described burner can be installed in the top of gasifier 49 to substitute burner 52.The gas that contains free oxygen is sent into the combustible gas in the second circular channel pipeline 68 that center conduit feeds this burner.At this moment, as not using mixing tank 41, then in gasifier, carry out mixing of mud and inflammable gas.

Method of the present invention has been carried out general description by embodiment, and the raw material of relevant particular composition only is used for clarification and explanation the present invention.Clearly, can be under the inspiration of the described content of preamble to this area professional to method disclosed herein and various modifications that raw material is done, but these are revised all within the determined scope of the present invention of claims.

Claims

1, a kind of method that is used for preparing fuel from sewage sludge, this method comprises:

(1) in belt filter pressing section, concentrates and contain about 0.5-20 weight % solid sewage sludge and contain about 15-65 weight % solid height sewage sludge that dewaters, and from described dehydration sewage sludge, isolate excessive water with generation;

(2) in about 130-200 heat-treatment temperature range, no air exists, under about 1-20 of the residence time minute and the barometric point, the sewage sludge that heating obtains from (1) in reaction zone, about 300 °F-650 °F subsequently in heat-treatment temperature range, no air exists down, about 5-120 of the residence time minute and continue to heat under the pressure of the vapour pressure that is equal to or higher than the water under this thermal treatment temp so that this sewage sludge decarboxylation and dehydrogenation and produce pumpable sewage sludge aqueous slurry;

(3) in flash zone, the pressure and the relevant temperature of the aqueous slurry of the sewage sludge that will obtain from (2) drop to the pressure range that about atmosphere is pressed onto the Saturated water vapor pressure under about 200-400 the described flash zone temperature of temperature range, from described sewage sludge, to evaporate and to separate enough water, obtain solids content about 30-70 weight % and have higher calorific value (HHV) about 5,000-9, the pumpable dehydration sewage sludge aqueous slurry of 500BTU/Lb;

(4) will be from (3) thus the slurry of the dewatered sludge that obtains and postcombustion mix the dehydration sewage sludge that obtains total solid content about 50-70 weight % and contain the 10-40 weight % that has an appointment mutually and to have higher calorific value about 5,000-14, but the pumping slurry of 000BTU/Lb.

2, a kind of method according to claim 1, this method comprises:

(5) under temperature about 1800-3000 and the about 1-30 barometric point of pressure, in the reaction zone of producer gas generator, with the materials flow that contains oxygen free body and temperature regulato will be from (4) but the pumping slurry partial oxidation that obtains contain the untreated exhaust flow of the heat of at least a gas of from following one group of gas, selecting with generation: synthesis gas, reducing gas and combustible gas.

3, a kind of basis the process of claim 1 wherein that the said pumpable fuel slurry that obtains from (4) can perfect combustion boiler or incinerator.

4, a kind of each method according to 1-3 item claim wherein concentrates the said sewage sludge in (1) under the following conditions, and this mud surface is applied 20-200psi(pound/square inch) left and right sides pressure, when continuing about 1/2-60 minute.

5, a kind of each method according to 1-3 item claim, wherein the sewage sludge in (1) be with the continuous belt press filtration and centrifugal combine carry out spissated.

6, a kind of each method according to 1-3 item claim is wherein preceding in step (4), will import centrifugal district from the pumpable dewatered sludge slurry that (3) obtain earlier and dewater.

7, a kind of method according to claim 1, wherein in (1), in continuous band press filtration district, in succession said mud is pressurizeed and make it concentrated, the about 20-200psi of surface pressure of the pressurization first time, about 1/2-60 minute clamping time, the about 200psi of surface pressure of the pressurization second time, the time of clamping time and the described first time of pressurization is close.

8, a kind of method according to claim 7, wherein described second time pressure dwell said mud is heated to about 100 ℃-140 ° and further dewaters.

9, a kind of basis the process of claim 1 wherein to the mud described in (1) pressurization, adds particle diameter simultaneously and further dewaters less than the flocculating aids of 2mm.

10, a kind of method according to claim 9, wherein said flocculating aids is selected from ickings and CaCO ₃

11, a kind of according to 1,2, the method for each of 3,7,8,9 and 10 claims, wherein the mud in (2) is heated to required temperature by carrying out heat exchange indirectly with steam or synthetic gas.