CN113526821B - Method and device for resource utilization of oily sludge in steel plant - Google Patents
Method and device for resource utilization of oily sludge in steel plant Download PDFInfo
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- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/10—Treatment of sludge; Devices therefor by pyrolysis
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- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
- C02F11/13—Treatment of sludge; Devices therefor by de-watering, drying or thickening by heating
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- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
- C10B53/00—Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form
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- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
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Abstract
A method and a device for recycling oily sludge in a steel plant, belonging to the field of sludge treatment. Loading oily sludge into a storage bin, pressing into cakes, mincing and scattering, proportionally adding lime, uniformly mixing and granulating; heating sludge particles, preheating, dehydrating and decomposing grease by using a high-temperature molten salt external heating mode; feeding sludge particles into a rotary hearth furnace, and further deeply pyrolyzing the sludge particles under the action of a microwave field under the anaerobic condition; after the sludge material in the product bin is cooled, transporting the product bin to a sintering plant; in a sintering plant, the sludge material after pyrolysis is taken as a sintering raw material for recycling, added into a sintering proportioning bin, and mixed into a uniform mixing ore according to the proportion required by the production process; according to the requirement of the alkalinity of the sintered ore, the addition amount of the flux is correspondingly reduced, and the sintered ore is produced by uniformly mixing and sintering, so that the oily sludge in a steel mill is treated harmlessly, the treatment efficiency and the energy use efficiency of the oily sludge are improved, and the resource utilization of the oily and ferric oxide sludge is realized.
Description
Technical Field
The invention belongs to the field of sludge treatment, and particularly relates to a method and a device for treating and recycling sludge containing oil and ferric oxide in a steel plant.
Background
At present, the total amount of various oily sludge generated in China every year reaches more than 1000 ten thousand tons, wherein the sludge generated in the steel industry accounts for more than 30 percent.
In order to eliminate contact heat generated between a casting blank and a casting roller during continuous casting and deformation heat generated between a steel blank and a roller during steel rolling, an iron and steel enterprise needs to adopt emulsion or special oil for cooling and lubricating, so that wastes with high oil content and iron oxide content, including oil-containing iron oxide scales and oil-containing sludge, are generated. These wastes need to be disposed of before they can be landfilled or recycled.
At present, the treatment process of oily sludge which is applied well at home and abroad mainly comprises a chemical hot washing method, a pyrolysis method and the like.
The chemical hot washing method is to utilize thermochemical solution to wash the oily sludge repeatedly to separate oil substances from the solid surface, and is widely applied to treating the oily sludge in oil fields. The disadvantages are that the oil recovery is not thorough, the excess sludge amount is large, secondary treatment is still needed, the labor intensity of the treatment process is large, and flushing liquid needs to be separately treated and can be discharged.
The pyrolysis treatment method is to dehydrate the oily sludge and decompose the grease under the condition of oxygen deficiency and a certain temperature, convert the oily sludge into three phase substances of solid, liquid and gas, and recycle oil, non-condensable gas and residual solid substances. The method has the advantages of thorough harmless treatment, effective solving of the pollution problem of the oily sludge, and simultaneous obtaining of oil, gas and solid resources. The disadvantages are large investment of treatment facilities and high energy consumption.
The pyrolysis of the oily sludge generally adopts a spiral kiln, a rotary hearth furnace, a multi-hearth furnace and the like, and the grease is heated and decomposed by electric heating, gas heating, fuel oil heating and the like to be removed.
The traditional heating mode has low heat transfer efficiency, the internal temperature distribution of the sludge is not uniform in the heating process, and water and grease are adsorbed in solid particle capillary pores and exist in a sporophyte form, so that the water and grease on the surface can only be removed in the pyrolysis process, the oil removal rate is low, the energy consumption is high, and the reactor is easy to coke.
Compared with the traditional heating, the microwave heating has the following advantages: 1) The microwave penetration capacity is strong, the inside of the oil sludge can be heated, and the sporophytes can be damaged, so that the whole sludge particles are uniformly heated, and the oil is thoroughly removed; 2) The microwave has catalytic pyrolysis effect, can reduce pyrolysis temperature and energy consumption; 3) The oil sludge is heated up instantly in a microwave field, the heating speed is high, the heat efficiency is high, and the temperature control is flexible; 4) Simple equipment, internal heating, little tail gas and environment-friendly process.
The invention discloses a method for accelerating the microwave pyrolysis process of oil-containing sludge by utilizing self-pyrolysis residues, which is disclosed in Chinese patent with the grant publication number of CN101798163B, wherein the grant day is 2011, 9 and 7, and the technical scheme is that oil sludge or sludge is subjected to microwave treatment for 5-15 minutes at 700-850 ℃ under the condition of nitrogen filling to obtain solid residues, then the solid residues are uniformly mixed with oil sludge or sludge according to 0.5-5% of the weight of the oil sludge or sludge, and then the oil sludge or sludge is subjected to microwave pyrolysis under the condition of nitrogen filling. According to the technical scheme, the hot solid residues are used as carriers for oil sludge auxiliary contact heating, so that the pyrolysis process of the oil sludge or the sludge can be accelerated, the pyrolysis time is shortened, the energy consumption of the treatment process is effectively saved, and the residues after microwave pyrolysis can be recycled. However, the microwave temperature of the oily sludge treated by the process is high, and the obtained product is only used as a microwave absorbent, so that the sludge is not subjected to reduction treatment.
The invention discloses a resource treatment method and a resource treatment device for oil-containing sludge in an oil field by microwave pyrolysis in Chinese invention patent with the grant date of 2012, 6.27.7 and the grant publication number of CN 101838094B, and the technical scheme is that the oil-containing sludge is sent into a closed reactor heated by microwave, the oil, gas and water generated by the pyrolysis treatment are recycled and reused at the temperature of 200-900 ℃, the residue after the pyrolysis is used as a roadbed material or is modified by nitric acid or NaOH, and the modified residue is used as an adsorption material. According to the technical scheme, the sludge is pyrolyzed only by microwaves, the energy consumption is high, the product of the sludge needs to be modified by nitric acid or NaOH, the technical process is complex, a large amount of chemical reagents are used, the recovery cost is increased, and the environmental protection pressure is increased.
The published date is 2017, 10 and 31, and the publication number is CN107304096A, the invention discloses an 'oily sludge pyrolysis treatment process technology', which comprises the steps of sequentially feeding oily sludge in the petroleum and petrochemical industries into a preheating section, a low-temperature section, a medium-temperature section and a high-temperature section of a device for pyrolysis, wherein the device of each pyrolysis section adopts jacket heat exchange or internal heating (the 1 st section to the 3 rd section respectively adopt fused salts with different melting points for external heating, and the 4 th section adopts electromagnetic heating at the temperature of 400-800 ℃); and the fraction generated by pyrolysis in each section is independently condensed and separated, the gas generated by pyrolysis is recycled, and the generated oil and water enter a phase separator for oil-water separation and oil and water recovery. The pyrolysis fraction separation device of the technical scheme is various and complex, the heating temperature of the high-temperature section is high, and the energy consumption is large.
How to solve the problems of complex process, low thermal efficiency, high energy consumption, large pyrolysis tail gas treatment capacity and the like of the existing pyrolysis treatment process of sludge containing oil and iron oxide in steel plants, realize resource utilization, and is a problem to be solved urgently in practical work.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method and a device for recycling oily sludge in a steel plant. Based on molten salt heating and microwave pyrolysis technologies, fuel gas generated by pyrolysis of burning oil sludge and part of blast furnace gas of a steel plant are used for heating molten salt, oil-containing sludge particles are preheated, dehydrated, heated and deoiled in a high-temperature molten salt external heating mode, and then microwaves are applied in a rotary hearth furnace for deep pyrolysis and deoiling; can completely remove grease (the oil content of the product is less than 0.1 percent, dry basis), remarkably improves the treatment efficiency and energy utilization efficiency of the oily sludge, and reduces energy consumption. The solid iron-containing substance obtained after low-temperature pyrolysis and oil removal can be used as a raw material for producing sintered ore in an iron and steel plant, and is mixed with the uniformly mixed ore, ignited and sintered to produce the sintered ore, so that the resource utilization of the sludge containing oil and ferric oxide is realized.
The technical scheme of the invention is as follows: the method for resource utilization of the oily sludge in the steel plant comprises the steps of heating the oily sludge to decompose and remove grease contained in the sludge by heating; the method is characterized in that:
1) Loading oily sludge into a storage bin, pressing into cakes, mincing and scattering, proportionally adding lime, uniformly mixing and granulating;
2) Feeding the sludge particles into a multi-stage pyrolysis kiln system, and heating and warming the sludge particles, preheating and dehydrating the sludge particles and decomposing grease in a high-temperature molten salt external heating mode;
3) Feeding sludge particles into a rotary hearth furnace, and further deeply pyrolyzing the sludge particles under the action of a microwave field under the anaerobic condition;
4) Discharging sludge particles subjected to deep pyrolysis from a discharge opening of the rotary hearth furnace, and discharging the sludge particles into a product bin through a water-cooling spiral discharging machine;
5) After the sludge material in the product bin is cooled, transporting the product bin to a sintering plant;
6) After the oil removing step is carried out on the oily sludge, the residual oil rate of the residual sludge material reaches below 0.1 percent;
7) In a sintering plant, the sludge material after pyrolysis is taken as a sintering raw material for recycling, added into a sintering proportioning bin, and mixed into a uniform mixing ore according to the proportion required by the production process; according to the requirement of the alkalinity of the sinter, the addition of the flux is correspondingly reduced, and the sinter is produced by uniformly mixing and sintering, so that the oily sludge of a steel mill is treated harmlessly, and the resource utilization is realized;
in the pyrolysis kiln system, a heating mode of externally heating high-temperature molten salt is adopted to preheat, dehydrate and heat to remove oil from sludge granules in each stage of pyrolysis kiln;
in the final pyrolysis process of the sludge, the sludge granular materials are further pyrolyzed by adopting a rotary hearth furnace kiln type and a microwave heating means;
the high-temperature molten salt is provided by a molten salt heating system;
the molten salt heating system mixes pyrolysis gas/noncondensable gas generated by the pyrolysis of the oil-containing sludge with blast furnace gas of a steel plant to heat molten salt.
The method for recycling the oily sludge in the steel plant adopts the technical scheme that the molten salt is heated by pyrolysis gas/noncondensable gas generated by pyrolysis of combustion oil sludge and part of blast furnace gas in the steel plant, and the oily sludge is preheated, dehydrated and heated to remove oil in a high-temperature molten salt external heating mode; then deep pyrolysis is carried out on the oily sludge in a rotary hearth furnace by adopting a microwave heating mode, grease in the oily sludge is removed, the treatment efficiency and the energy utilization efficiency of the oily sludge are improved, and the energy consumption is reduced; meanwhile, the solid iron-containing substance obtained after deep pyrolysis and oil removal is used as a raw material for producing sintered ore in an iron and steel plant, and is mixed with the uniformly mixed ore, ignited and sintered to produce the sintered ore, so that resource utilization of sludge containing oil and ferric oxide is realized.
Specifically, the proportion of the lime is 4-6%; controlling the diameter size of the granulated oily sludge particles within the range of 5-20 mm; the temperature of the high-temperature molten salt flowing in the jackets of the pyrolysis kilns at all stages is controlled within the range of 350-480 ℃; the temperature of the deep pyrolysis is controlled within the range of 400-500 ℃; the time of the deep pyrolysis is controlled within the range of 30-40 min.
The heating mode of the external heating of the high-temperature molten salt comprises that each stage of spiral heating kiln adopts a sleeve type double-layer structure, and the high-temperature molten salt circularly flowing in an outer sleeve of the pyrolysis kiln heats sludge particle pellet materials in an inner sleeve of each stage of pyrolysis kiln; the flow direction of the high-temperature molten salt is opposite to that of the sludge particle pellet material.
Specifically, the high-temperature molten salt enters from an external heating jacket at a middle temperature section of a multistage pyrolysis kiln system through a pipeline, then sequentially flows through a low-temperature section spiral kiln jacket and a preheating section spiral kiln jacket, and sludge particle materials in an inner cylinder of the spiral kiln are heated or preheated in a heat conduction mode, so that the integral heating of a kiln body of the spiral kiln is realized, the preheating and temperature rising speed of oil-containing sludge is improved, and the total pyrolysis energy consumption is saved;
the sludge particles pass through a preheating section, a low-temperature section and a medium-temperature section of the multistage pyrolysis kiln system, the temperature is gradually increased, water evaporation is carried out in the preheating section of the pyrolysis kiln, and water evaporation and grease decomposition are carried out in the low-temperature section and the medium-temperature section of the pyrolysis kiln.
Specifically, the molten salt heating system comprises a molten salt heating furnace; the molten salt heating furnace adopts pyrolysis gas/noncondensable gas containing oily sludge as fuel and blast furnace gas of a steel mill as auxiliary fuel gas; dust-containing gas generated during pyrolysis of the oil-containing sludge enters an oil-gas separator after dust removal, oil and pyrolysis gas/non-condensable gas are separated, and the pyrolysis gas/non-condensable gas enters a gas storage cabinet; and mixing the pyrolysis gas/non-condensable gas in the gas storage cabinet with blast furnace gas, and supplying the gas to a gas burner of the molten salt heating furnace for combustion according to the operating process requirements and conditions of the molten salt heating furnace.
Furthermore, in the technical scheme of the invention, the added lime is used for desulfurizing the pyrolysis gas in the pyrolysis treatment process of the sludge particles.
The invention also provides a device for recycling the oily sludge of the steel plant by adopting the method, which is characterized in that:
the device at least comprises a mixer, a spiral feeder, a multi-stage spiral pyrolysis kiln system, a rotary hearth furnace, a pyrolysis oil-gas leading-out and separating system, a spiral discharging machine and a storage bin which are connected in sequence;
the mixer and the screw feeder are used for mixing the oily sludge with lime in proportion, and uniformly mixing and granulating the oily sludge;
the multi-stage spiral pyrolysis kiln system is used for preheating and heating the oily sludge to realize water evaporation and grease decomposition;
the rotary hearth furnace is provided with a microwave generator and an electric control system and is used for further carrying out grease pyrolysis on the oily sludge so as to realize the final deep pyrolysis process of the oily sludge;
the molten salt heating circulation system comprises a molten salt heating furnace, a molten salt circulating pump, a molten salt melting tank and a molten salt circulating pipeline; molten salt in the melting tank is sent into a molten salt heating furnace by a molten salt circulating pump to be heated, and is heated and melted into high-temperature molten salt fluid which is then conveyed to a pyrolysis kiln system; the high-temperature molten salt fluid flows to the preheating section pyrolysis kiln jacket from the middle-temperature section pyrolysis kiln jacket and the low-temperature section pyrolysis kiln jacket in sequence under the driving of the molten salt circulating pump, and finally flows back to the molten salt melting tank through the pipeline;
the pyrolysis oil gas leading-out and separating system is used for leading out and removing dust of high-temperature oil gas mixture containing dust, water vapor and gaseous oil mist generated by water evaporation and grease pyrolysis in the oil-containing sludge in the rotary hearth furnace and the low-temperature section and the medium-temperature section pyrolysis kiln; after dedusting, the collected dust returns to a sludge storage bin for retreatment. The high-temperature oil gas enters a spraying oil catching device, oil products and non-condensable gas are separated after spraying and cooling, the mixture of oil and water is subjected to oil-water separation in an oil-gas separation tower, oil products are recovered, and the non-condensable gas enters a gas storage cabinet;
the non-condensable gas entering the gas storage cabinet is mixed with blast furnace gas of the iron and steel plant and sent into a molten salt heating furnace to heat molten salt.
The multi-stage spiral pyrolysis kiln system consists of 2-4 stages of spiral heating kilns; all the spiral heating kilns adopt a sleeve type structure, the outer surface of the spiral heating kiln is covered with a heat insulation material, and the inner cylinder is provided with a shaftless spiral which is driven by a motor to drive the oil-containing sludge to turn over and move.
Specifically, the tail part of the preheating section pyrolysis kiln is provided with a hot waste gas inlet, and the hot waste gas of 400-500 ℃ generated after fuel gas of the molten salt heating furnace is mixed with air to be cooled to below 250 ℃ and enters from the inlet to exchange heat of sludge in a gas-solid convection mode and take away moisture evaporated from the surface.
Specifically, the inner cylinders of the low-temperature section pyrolysis kiln and the middle-temperature section pyrolysis kiln and the top of the rotary hearth furnace are respectively provided with an exhaust hole which is connected with an oil gas exhaust main pipe through an exhaust pipeline; the oil gas discharge main pipe is connected with the dust remover; each exhaust branch pipe and each exhaust main pipe are coated with heat insulation cotton or are subjected to electric tracing for heat preservation; hot flue gas coil pipes are arranged on a section of exhaust main pipe close to the dust remover and a lower cone of the dust remover, and 250-300 ℃ hot waste gas generated by mixing waste gas combusted by the molten salt heating furnace and part of cold air is added is introduced to carry out external heating and heat preservation, so that the temperature of oil gas volatilized by sludge pyrolysis is not lower than 160 ℃, and oil substances are prevented from being separated out to block pipelines and the dust remover; the hot waste gas passing through the hot flue gas coil pipe and the water gas exhausted from the preheating section heating kiln are pumped out by an induced draft fan and exhausted to the atmosphere.
Furthermore, the oil-containing sludge enters a feed inlet of the preheating section pyrolysis kiln and the product materials are discharged to a discharge outlet of a discharge hopper from the rotary hearth furnace, two gate valves are respectively arranged and are controlled in an interlocking manner, so that the situation that air is difficult to enter the rotary hearth furnace and the inner barrel of the spiral heating kiln when feeding, discharging and stopping is ensured, and oil gas combustion is prevented.
The molten salt heating furnace adopts a three-return vertical cylindrical coil gas molten salt heating furnace.
The microwave generator comprises microwave generator magnetrons, wherein at least 2 microwave generator magnetrons are connected in series to form a plurality of groups of microwave generators, each group of microwave generators is arranged above a grate plate of the rotary hearth furnace, each group can be independently started and stopped, and microwave heating power is controlled according to the temperature of sludge pellets discharged by the spiral heating kiln at the middle temperature section and the temperature requirement of the pellets in the rotary hearth furnace, so that the pyrolysis temperature can be flexibly controlled and adjusted.
Furthermore, the microwave generator magnetrons are connected in series by 3 groups, are arranged in 3-4 groups, are uniformly distributed above a grate plate of the rotary hearth furnace, and directly act on the oily sludge material through the metal waveguide, so that the oily sludge material on the cross section of the grate is uniformly and quickly heated integrally. After pyrolysis treatment at 400-500 ℃ for 30-40min, the organic grease in the pellets is also fully decomposed, and the oil removal process of deep pyrolysis is completed.
According to the technical scheme, lime is added into sludge containing oil and ferric oxide, the sludge is mixed and pelletized, the sludge is preheated and heated by high-temperature molten salt after entering a pyrolysis kiln system, microwave is applied to the sludge for pyrolysis after the temperature reaches about 400 ℃, organic matters in the sludge are completely decomposed by the rapid temperature rise and integral heating of a metal waveguide and the penetrating and wall-breaking effects on the inside of sludge pellets, and the oil content is reduced to be below 0.1%;
the residual solid matters after treatment are directly used as iron-containing raw materials of steel plants for producing sintered ores, so that the oily sludge of the steel plants is harmlessly treated, and resource utilization is realized.
Compared with the prior art, the invention has the advantages that:
1. after the technical scheme is adopted to remove oil from oily sludge in a steel plant, the residual oil rate of the remaining substances can reach below 0.1 percent (dry basis), and the oil is completely and thoroughly removed; the deoiled solid bulk material has higher iron-containing grade and contains a certain amount of alkaline oxide (CaO), and is directly used for sintering production, so that the oily sludge of a steel mill is subjected to harmless treatment and resource utilization is realized; the oily sludge is added with lime, so that the surface moisture and grease can be absorbed favorably, the viscosity of the oily sludge can be reduced favorably, the materials can be dispersed and granulated conveniently, and the oily sludge can be uniformly dispersed in the inner cylinder of the spiral heating kiln favorably; the part of lime can be used as a flux for producing sintered ores;
2. according to the technical scheme, the microwave pyrolysis technology is adopted according to the physical characteristics of the oily sludge of the steel plant and the strong wave absorption characteristics of iron oxides in the oily sludge, the non-gradient, uniform and integral pyrolysis of oily sludge balls can be realized, the wall breaking effect of a microwave field on organic matters is exerted, the deoiling rate is high, the oil removal is thorough, the heating speed is high, the pyrolysis temperature is low, the treatment time is short, the treatment efficiency of the oily sludge can be greatly improved, and the energy consumption is reduced; the pyrolysis equipment of the rotary hearth furnace is adopted, the cross section area of microwave treatment is large, and the treatment capacity of the equipment is high;
3. the non-contact heating mode of the fused salt external heating and the microwave field is adopted, no waste gas enters the sludge pyrolysis oil gas in the treatment process, the treatment capacity of the flue gas is small, the heat value of the pyrolysis gas is high, and the pyrolysis gas is used as the fuel gas of the fused salt heating furnace; in addition, only one molten salt heating system is adopted to heat each section of spiral heating kiln, so that the process equipment is simple and the operation and the control are convenient;
4. the oily sludge is heated and pyrolyzed in a preheating section, a low-temperature section and a middle-temperature section by adopting a multi-stage spiral kiln, the sludge is driven to turn and advance by a shaftless spiral blade, oily sludge globules move along the inner wall of an inner cylinder of the kiln and are continuously scraped by the blade, the heating is uniform, the oily sludge is not easy to adhere to the inner wall and coke, the process is stable, and the failure rate of a spiral feeding device is low;
5. the high-temperature molten salt is used as a heat source for preheating and heating the oil sludge, the heat conduction efficiency is high, the heating is uniform, pyrolysis gas generated by the sludge is used as energy in the oil sludge preheating and heating process, the microwave heating is only adopted in a main pyrolysis section, the two heating modes are combined, the energy is reasonably and efficiently used, and the total energy consumption is low; the waste gas of the molten salt heating furnace is also used for heat preservation of an oil-gas pipeline and a dust remover, and the residual energy is fully utilized;
6. the oil gas evaporated and volatilized from the oily sludge in the treatment of the spiral heating kiln and the pyrolysis kiln of the rotary hearth furnace is treated by a fraction separation system in a centralized way, and the process equipment is simple; in the sludge pyrolysis treatment process, the added lime is used for desulfurizing the pyrolysis gas, no pollutant gas is discharged, and the whole treatment process is environment-friendly.
Drawings
FIG. 1 is a schematic view of the process flow of the present invention for removing oil from oily sludge by pyrolysis;
FIG. 2 is a schematic diagram of the equipment system of the oil-containing sludge pyrolysis oil removal process.
In the figure, 1 is a preheating section, 2 is a low-temperature section, 3 is a middle-temperature section, 4 is a microwave generator, and 5 is a discharge screw.
Detailed Description
The oily sludge (sludge for short) in the technical scheme is sludge containing lubricating grease and ferric oxide in a steel plant, and the sludge usually comprises oily (usually 13-20%), water (usually 15-22%) containing steel rolling oily sludge, oily (usually 0.5-1.5%) containing oil and water (usually 2-10%) containing oily ferric oxide.
Unlike oil-containing sludge from oil fields, sludge from steel plants is sludge containing lubricating greases and iron oxides, which are high in iron oxide content (typically 35-45%) and low in water content (2-20%). But the technical scheme can also be suitable for the oil removal treatment of various oily sludge in the petroleum and metallurgy industries.
As an extension, when the technical scheme of the invention is adopted, the oily iron scale can be mixed into the hot-rolled oily sludge for subsequent oil removal treatment.
The technical solution of the present invention will be further explained below with reference to the schematic process flow diagram shown in fig. 1 and the schematic process equipment system diagram of fig. 2.
Loading oily sludge into a storage bin, pressing into cakes, mincing, scattering, adding 4-6% of lime, uniformly mixing, and granulating, wherein the diameter size of a sludge ball is controlled within the range of 5-20 mm.
The sludge pellets are then fed into the pyrolysis kiln system by a screw conveyor (labeled as screw feeder in the figure).
The pyrolysis kiln system is a multilayer (or multi-section) spiral heating kiln (also called a sludge heating kiln or a heating kiln).
And a rotary hearth furnace is arranged at the discharge end of the pyrolysis kiln system.
A distributor is arranged between the discharge end of the pyrolysis kiln system and the rotary hearth furnace; a plurality of groups of microwave generators are arranged above the rotary hearth furnace; the discharge end of the rotary hearth furnace is correspondingly connected with the feed end of the water-cooling spiral discharge machine through a pipeline; the discharge end of the water-cooling spiral discharge machine is connected with the storage bin through a pipeline.
The sludge pellets are firstly preheated for dehydration and heated for temperature rise in a multi-section spiral heating kiln (3 sections of spiral heating kilns are taken as an example in figure 2, wherein 1 is a preheating section of the spiral heating kiln, 2 is a low-temperature section of the spiral heating kiln, and 3 is a middle-temperature section of the spiral heating kiln), then are pyrolyzed for 30-40min under the anaerobic condition at the temperature of 400-500 ℃ under the action of a microwave field in a rotary hearth furnace, are discharged from a discharge port, are discharged into a product bin through a water-cooled spiral heating machine, and are transported to a sintering plant after being cooled.
The sludge heating kiln is heated from a preheating section, a low-temperature section to a medium-temperature section by high-temperature molten salt circularly flowing in an outer sleeve of the sludge heating kiln, and the high-temperature molten salt is provided by a molten salt heating system (a molten salt heating furnace for short).
The molten salt heating furnace adopts oil-containing sludge pyrolysis gas (non-condensable gas) as fuel and blast furnace gas of a steel mill as auxiliary fuel gas. Dust-containing gas generated during pyrolysis of the oil-containing sludge enters an oil-gas separator after dust removal, oil and non-condensable gas are separated, and the non-condensable gas enters a gas storage cabinet.
After the non-condensable gas in the gas storage cabinet is mixed with blast furnace gas, the mixed gas is supplied to a gas burner of the molten salt heating furnace for combustion according to the operation process requirements and conditions of the molten salt heating furnace.
The temperature of the fused salt at the outlet of the fused salt heating furnace is controlled between 450 and 550 ℃. Under the action of a molten salt pump (not shown in the figure), heated molten salt enters from an external heating jacket of a middle-temperature section of the spiral heating kiln through a pipeline, then flows through the jacket of the spiral kiln of the low-temperature section and the jacket of the spiral kiln of the preheating section in sequence, and oil sludge in an inner cylinder of the kiln is heated or preheated in a heat conduction mode, so that the sludge is gradually raised from the normal temperature to reach about 400 ℃ in the last section (middle-temperature section). The molten salt circularly flows in a pipeline of the molten salt heating system.
The sludge pellets enter a first section of spiral kiln (preheating section) from a feeding hole, slowly move forwards and turn over under the drive of a spiral blade, pass through the preheating section, the low-temperature section and the medium-temperature section, gradually rise in temperature, evaporate moisture in the preheating section, and evaporate moisture and decompose grease in the low-temperature section and the medium-temperature section.
The hot sludge pellets (called hot pellets or sludge pellets for short) from the last section (middle temperature section) of the spiral heating kiln enter the rotary hearth furnace for further pyrolysis.
The thermal pellets are uniformly distributed on a grate plate which rotates in the rotary hearth furnace through a distributing device, a plurality of groups of microwave generators 4 are arranged at the top of the rotary hearth furnace, and the thermal pellets directly act on the sludge pellets through metal waveguides, so that the temperature of the pellets on the cross section of the grate is uniformly and rapidly raised integrally. The organic grease in the pellets is also fully decomposed by the pyrolysis treatment at the temperature of 400-500 ℃ for 30-40min, and the oil removing process is completed.
The treated sludge pellets or pellet bulk materials are discharged from a discharge port of the rotary hearth furnace through a discharge screw 5 (short for a discharge screw), and then are discharged into a product bin through a water-cooling screw discharging machine of a discharging hopper, and can be transported to a sintering plant after being cooled.
Lime (CaO) added into the oily sludge and SO in the grease pyrolysis gas in the pyrolysis process 2 The reaction absorbs gas sulfide (which is fixed in solid materials), and reduces the pollution emission of pyrolysis gas (when the molten salt heating furnace is burnt).
Made of potassium nitrate (KNO) 3 ) Sodium nitrite (NaNO) 2 ) And sodium nitrate (NaNO) 3 ) The formed mixed molten salt has low melting point, high working temperature under normal pressure, stable property (no expansion and no gas generation) at high temperature (150-550 ℃), large specific heat capacity and thermal conductivity 2 times that of other organic heat carriers (such as heat conduction oil). And the material is not explosive and not combustible.
The high-temperature molten salt liquid is used as a preheating and heating medium of the sludge, so that the whole heating of the spiral kiln barrel can be realized, the preheating and temperature rising speed of the sludge is improved, and the total pyrolysis energy consumption is saved.
Obviously, as shown in fig. 2, the flow direction of the high-temperature molten salt liquid in the technical scheme is opposite to the flow direction of the sludge globule material, which is a conventional heat exchange mode in the heat exchange technology, and the heat exchange principle thereof is not described herein.
As mentioned above, the technical scheme of the invention adopts the rotary hearth furnace kiln type and the microwave heating means in the final sludge pyrolysis process.
The microwave heating can realize gradient-free, integral, synchronous and uniform heating of the sludge, the temperature rise is rapid, the pyrolysis temperature is reduced under the action of microwave catalysis, and the treatment time is shortened; more prominent effect is that microwave energy can effectively break the wall of oil and water existing in oil sludge by sporophytes, so that water in sludge pellets is thoroughly evaporated, organic matters such as grease and the like are thoroughly decomposed, solid and liquid are thoroughly separated, and the oil removal rate of sludge is greatly improved.
Microwave heating equipment controllability is good, and it is convenient to maintain, and safety (microwave leakage absolute control is within the safe limit), pyrolysis process are clean, only mud self pyrolysis flue gas produces, compare interior hot type (burning coal gas) heating, are showing the handling capacity that has reduced the pyrolysis smoke and dust.
Since the microwave heating device is a prior art, the structure, connection mode or operation principle of the microwave generator and the microwave control system (also called an electric control system) shown in fig. 2 will not be further described.
In the technical scheme, because the chemical components of the oily sludge contain iron, a microwave absorbent does not need to be added, the microwave temperature is low, and the obtained product can be used for sintering, so that the sludge is reduced and recycled.
As described in the above treatment process, the device specifically related to the technical scheme of the invention comprises a multistage spiral molten salt heating kiln, a microwave rotary hearth furnace pyrolysis kiln and a logistics control system thereof, a molten salt heating circulation system, a microwave generator, an electric control system, a pyrolysis oil gas leading-out and separating system (including an exhaust fan) and the like.
Wherein, the spiral heating kiln is composed of 2-4 stages (sections), and the number of the sections can be selected according to the sludge treatment capacity, the length of the spiral heating kiln, the temperature and the flow of the molten salt, the heating power of microwave equipment of the rotary hearth furnace and the like.
The spiral heating kilns at all levels (sections) adopt a sleeve type structure, are covered with heat insulation materials, are provided with shaftless spirals in the inner cylinder, and are driven by a motor to drive the oily sludge to turn over and move.
The material outlet of the upper section of spiral heating kiln is connected with the material inlet of the lower section of spiral heating kiln by a short pipe lined with refractory material; the outer cylinder (jacket) of each stage (section) of the spiral heating kiln is filled with molten salt with the temperature of 350-480 ℃, and molten salt fluid flows from the jacket of the middle-temperature section heating kiln to the jacket of the preheating section heating kiln under the power drive of a molten salt pump and then flows back to the molten salt heating furnace for heating.
The tail part of the heating kiln of the preheating section is provided with a hot waste gas inlet, and the hot waste gas of 400-500 ℃ generated after the fuel gas of the molten salt heating furnace is mixed with air to be cooled to below 250 ℃, and enters from the inlet to exchange heat of the sludge in a gas-solid convection mode and take away moisture evaporated from the surface.
The inner cylinder of the low-temperature section and the middle-temperature section heating kiln and the top of the rotary hearth furnace are respectively provided with an exhaust hole which is connected with an oil gas exhaust main pipe through an exhaust pipeline (branch pipe), and the oil gas exhaust main pipe is connected with a dust remover. The exhaust branch pipes and the exhaust main pipe are coated with heat insulation cotton or electric tracing heat for heat preservation, a section of the exhaust main pipe close to the dust remover and a lower cone of the dust remover are respectively provided with a hot flue gas coil pipe, 250-300 ℃ hot waste gas generated by mixing waste gas combusted by a molten salt heating furnace and part of cold air is added is introduced to carry out external heating heat preservation, the temperature of oil gas volatilized by sludge pyrolysis is not lower than 160 ℃, and oil substances are prevented from being separated out to block pipelines and the dust remover.
The hot waste gas passing through the hot flue gas coil pipe and the water gas exhausted from the preheating section heating kiln are pumped out by an induced draft fan and exhausted to the atmosphere.
The mixture containing dust, vapor and gaseous oil mist generated by moisture evaporation and grease pyrolysis of oily sludge in the rotary hearth furnace and the low-temperature section and the medium-temperature section heating kiln is pumped out under the negative pressure action of the Roots blower, dust is removed firstly, and the collected dust returns to the sludge storage bin for treatment. And the high-temperature oil gas enters a two-stage spraying oil catching device, oil products and non-condensable gas are separated through spraying and condensation, the mixture of the oil and the water is subjected to oil-water separation, oil products are recovered, and the non-condensable gas enters a gas storage cabinet.
The feed inlet that gets into the preheating section heating kiln at oiliness mud and the discharge gate that the product material discharged the hopper from the rotary hearth furnace all set up twice push-pull valve, and the interlocking control of twice push-pull valve (can only one open, another is closed), guarantees that the air is difficult to get into rotary hearth furnace and spiral heating kiln inner tube when feeding, ejection of compact and shut down, prevents oil gas burning.
The molten salt heating system is composed of a molten salt heating furnace, a molten salt circulating pump, a molten salt melting tank and a molten salt circulating pipeline. The molten salt heating furnace comprises a molten salt heating furnace body, a gas pipeline, a burner, a combustion fan, a combustion control device and the like.
The fused salt circulating pipelines are all insulated by adopting an insulation material, so that the fused salt cooling is slowed down and the fused salt solidification is prevented.
After the hot waste gas generated by the combustion of blast furnace gas used by the molten salt heating furnace is heated and melted by the heating pipe in the melting tank and flows sufficiently, the molten salt is sent into the molten salt heating furnace by the circulating pump to be heated, and is conveyed to the spiral heating kiln system (entering from an outer jacket of the heating kiln at the last stage, namely the middle-temperature section) after reaching the required outlet temperature, and finally returns to the melting tank.
The three-pass vertical cylindrical coil gas molten salt heating furnace has the advantages of compact structure, high heat efficiency, strong gas adaptability, safety, reliability, quick start, convenient operation and the like.
The microwave generator magnetron arranged on the rotary hearth furnace adopts 3 sets of series connection, a plurality of sets can be arranged, generally 3-4 sets are arranged, the sets are distributed in a balanced manner, each set can be started and stopped independently, and the microwave heating power is controlled according to the temperature of sludge pellets discharged by the medium-temperature spiral heating kiln and the temperature requirement of pellets in the rotary hearth furnace, so that the pyrolysis temperature can be flexibly controlled and adjusted.
In summary, according to the technical scheme of the invention, lime is added into sludge (including oily iron scale) containing oil and iron oxide, the sludge is mixed and pelletized, the sludge is preheated and heated by high-temperature molten salt after entering a pyrolysis kiln system, the temperature reaches about 400 ℃ (usually 370-420 ℃), then microwave is applied for pyrolysis, the pyrolysis temperature is 400-500 ℃, the pyrolysis time is 30-40min, organic matters in the sludge are completely decomposed by rapid temperature rise and integral heating of a metal waveguide and penetration and wall breaking effects on the inside of the sludge pellets, and the oil content is reduced to below 0.1%.
The residual solid matter after treatment is directly used as iron-containing raw material of steel plant for producing sintered ore. Combustible gas generated by oil sludge pyrolysis is used as fuel, molten salt is heated after full combustion, and hot waste gas generated by combustion is used for supplying heat to the oil-gas pyrolysis pipeline and dust removal equipment for heat preservation and is used for melting the molten salt.
Example (b):
example 1:
in this example, the physical properties of hot-rolled oily sludge in a steel plant are shown in Table 1.
TABLE 1 oily sludge Properties
| Name(s) | Water content of% | Oil content, percent | Bulk density, g/cm 3 |
| Oil-containing iron scale | 9.32 | 1.98 | 2.50 |
| Hot rolling oil-containing sludge | 5.19 | 10.97 | 1.02 |
Adding the oily sludge into a storage bin, mincing, adding 6% of lime, stirring, uniformly mixing and granulating.
Starting a molten salt heating system and a pyrolysis flue gas treatment system, circulating and flowing liquid molten salt in each section of jacket of the spiral heating kiln for 5-10min, then starting a spiral feeder and motors of each section of spiral kiln, and increasing the blast furnace gas amount of the molten salt heating furnace to enable the outlet molten salt temperature of the molten salt heating furnace to reach 500 ℃.
And starting the rotary trolley of the rotary hearth furnace and the microwave heating electric control system, and preheating and heating the oil-containing sludge through the first section to the third section of the spiral kiln.
And (3) after the temperature of the sludge reaches 400 ℃, entering a microwave rotary hearth furnace, and controlling the rotating speed of a rotary trolley of the rotary hearth furnace and the power of microwaves to pyrolyze sludge particles for 40min at 460-470 ℃ in the rotary hearth furnace.
Starting the rotary hearth furnace discharging screw, successively opening 2 discharging valves of the rotary hearth furnace discharging port, and discharging the processed solid materials to a finished product bin by a water-cooling screw discharging machine.
When the sludge pyrolysis system normally operates for a certain time and the pyrolysis non-condensable gas storage cabinet reaches a certain gas storage amount, the pyrolysis gas pipeline valve is opened to be communicated with the blast furnace gas pipeline, the gas of the molten salt heating furnace is changed into mixed gas, and the blast furnace gas consumption of the molten salt heating system is correspondingly reduced.
The oil content of the treated solid was found to be 0.08% by inspection, and the chemical composition is shown in Table 2.
Table 2 chemical composition of oily sludge after oil removal (%)
| TFe | FeO | SiO 2 | CaO | MgO | Al 2 O 3 | P 2 O 5 | K 2 O | Na 2 O | Cl | PbO | ZnO |
| 67.78 | 43.55 | 0.82 | 2.91 | 0.05 | 0.42 | 0.18 | ＜0.01 | ＜0.05 | 0.08 | ＜0.005 | 0.038 |
Example 2:
in this example, hot-rolled oily sludge from a steel plant is taken as an example, and the physical properties thereof are shown in table 1.
Adding the oily sludge into a storage bin, mincing, adding 5% of lime, stirring, uniformly mixing and granulating.
Starting a molten salt heating system and a pyrolysis flue gas treatment system, enabling liquid molten salt to circularly flow in each section of jacket of the spiral heating kiln for 5-10min, then starting a spiral feeder and a motor of each section of spiral kiln, and increasing the blast furnace gas amount of the molten salt heating furnace to enable the outlet molten salt temperature of the molten salt heating furnace to reach 500 ℃.
Starting a rotary trolley of the rotary hearth furnace and a microwave heating electric control system, preheating and heating the oil-containing sludge through the first section to the third section of the spiral kiln, and feeding the sludge into the microwave rotary hearth furnace after the temperature of the sludge reaches 380 ℃.
The rotating speed of the rotary trolley of the rotary hearth furnace and the power of the microwave are controlled, so that the sludge particles are pyrolyzed for 30min at 480 ℃ in the rotary hearth furnace.
Starting the rotary hearth furnace discharge screw, successively opening 2 discharge valves of the rotary hearth furnace discharge port, and discharging the processed solid material to a finished product bin by a water-cooling screw discharge machine.
When the sludge pyrolysis system normally operates for a certain time and the pyrolysis non-condensable gas storage cabinet reaches a certain gas storage amount, the pyrolysis gas pipeline valve is opened to be communicated with the blast furnace gas pipeline, the gas of the molten salt heating furnace is changed into mixed gas, and the blast furnace gas consumption of the molten salt heating system is correspondingly reduced.
The oil content of the treated solid was found to be 0.06%, and the chemical composition is shown in Table 3.
TABLE 3 chemical composition (%) of deoiled oily sludge
| TFe | FeO | SiO 2 | CaO | MgO | Al 2 O 3 | P 2 O 5 | K 2 O | Na 2 O | Cl | PbO | ZnO |
| 68.85 | 42.62 | 0.85 | 2.96 | 0.06 | 0.41 | 0.19 | ＜0.01 | ＜0.05 | 0.085 | ＜0.005 | 0.038 |
The rest is the same as example 1.
Example 3:
in this example, the physical properties of hot-rolled oily sludge in a steel plant are shown in Table 1.
Adding the oily sludge into a storage bin, mincing, adding 4% of lime, stirring, uniformly mixing and granulating. Starting a molten salt heating system and a pyrolysis flue gas treatment system, circulating and flowing liquid molten salt in each section of jacket of the spiral heating kiln for 5-10min, then starting a spiral feeder and motors of each section of spiral kiln, and increasing the blast furnace gas amount of the molten salt heating furnace to enable the outlet molten salt temperature of the molten salt heating furnace to reach 500 ℃.
Starting a rotary trolley of the rotary hearth furnace and a microwave heating electric control system, preheating and heating the oil-containing sludge through the first section to the third section of the spiral kiln, feeding the sludge into the microwave rotary hearth furnace after the temperature of the sludge reaches 400 ℃, and controlling the rotating speed of the rotary trolley of the rotary hearth furnace and the power of microwaves to pyrolyze sludge particles in the rotary hearth furnace for 30min at 500 ℃.
Starting the rotary hearth furnace discharge screw, successively opening 2 discharge valves of the rotary hearth furnace discharge port, and discharging the processed solid material to a finished product bin by a water-cooling screw discharge machine.
When the sludge pyrolysis system normally operates for a certain time and the pyrolysis non-condensable gas storage cabinet reaches a certain gas storage amount, the pyrolysis gas pipeline valve is opened to be communicated with the blast furnace gas pipeline, the gas of the molten salt heating furnace is changed into mixed gas, and the blast furnace gas consumption of the molten salt heating system is correspondingly reduced.
The oil content of the treated solid was found to be 0.04%, and the chemical composition is shown in Table 4.
Table 4 chemical composition of deoiled oil-containing sludge (%)
| TFe | FeO | SiO 2 | CaO | MgO | Al 2 O 3 | P 2 O 5 | K 2 O | Na 2 O | Cl | PbO | ZnO |
| 68.73 | 41.58 | 0.87 | 2.89 | 0.06 | 0.40 | 0.18 | ＜0.01 | ＜0.05 | 0.08 | ＜0.005 | 0.038 |
The rest is the same as example 1.
The solid products (also called solid iron-containing materials) obtained in the three embodiments can be used as sintering raw materials for recycling.
Specifically, the solid iron-containing material treated by the technical scheme of the invention is transported to a sintering plant to be recycled as a sintering raw material, and then is added into a sintering proportioning bin to be proportioned into a uniform mixing ore according to the proportion required by the production process; according to the requirement of the basicity of the sintered ore (usually 1.8-2.0), the addition amount of the flux is correspondingly reduced, and the sintered ore is produced by uniformly mixing and sintering, so that the oily sludge of a steel mill is harmlessly treated, and the resource utilization is realized.
The oily sludge pyrolysis system provided by the technical scheme of the invention can treat oily sludge (including steel rolling oily iron scale, hot rolling oily sludge, machining oily sludge and the like) in a steel plant and can also treat oily sludge in an oil field.
According to the technical scheme, lime is added into sludge containing oil and ferric oxide (including oily iron scale), the sludge is mixed and pelletized, the sludge is preheated and heated through high-temperature molten salt after entering a pyrolysis kiln system and reaches about 370-420 ℃, then microwave is applied to carry out pyrolysis, the pyrolysis temperature is 400-500 ℃, the pyrolysis time is 30-40min, organic matters in the sludge are completely decomposed through rapid temperature rise and integral heating of a metal waveguide and penetration and wall breaking effects on the interior of sludge pellets, and the oil content is reduced to be below 0.1%. The residual solid matter after treatment can be directly used as iron-containing raw material of steel plants for producing sinter. Combustible gas generated by pyrolysis of oil sludge is used as fuel, molten salt is heated after full combustion, and hot waste gas generated by combustion is used for heat preservation of an oil-gas pyrolysis pipeline and dust removal equipment and is used for melting the molten salt.
The invention can be widely used in the fields of treatment and resource utilization of sludge containing oil and ferric oxide in steel plants.
Claims (10)
1. A method for resource utilization of oily sludge in steel plants comprises heating the oily sludge to decompose oil contained in the sludge and remove the oil; the method is characterized by comprising the following steps:
1) Loading oily sludge into a storage bin, pressing into cakes, mincing and scattering, proportionally adding lime, uniformly mixing and granulating;
2) The sludge particles are sent into a multi-stage pyrolysis kiln system, pyrolysis gas/noncondensable gas generated by pyrolysis of the burning oil sludge and part of blast furnace gas of a steel plant are used for heating molten salt, and heating, preheating and dehydration and grease decomposition are carried out on the sludge particles in a high-temperature molten salt external heating mode;
3) Sludge particles are fed into a rotary hearth furnace, a microwave heating mode is adopted in the rotary hearth furnace, and under the action of a microwave field, deep pyrolysis oil removal is further performed under the anaerobic condition, so that the treatment efficiency and the energy use efficiency of oily sludge are improved, and the energy consumption is reduced;
4) Discharging sludge particles subjected to deep pyrolysis from a discharge opening of the rotary hearth furnace, and discharging the sludge particles into a product bin through a water-cooling spiral discharging machine;
5) After the sludge material in the product bin is cooled, transporting the product bin to a sintering plant;
after the oil removing step is carried out on the oily sludge, the residual oil rate of the residual sludge material reaches below 0.1 percent;
6) In a sintering plant, the sludge material after pyrolysis is recycled as a raw material for producing sintered ore in an iron and steel plant, and is added into a sintering proportioning bin and mixed into uniform mixed ore according to the proportion required by the production process; according to the requirement of the alkalinity of the sintered ore, the addition amount of the flux is correspondingly reduced, and the sintered ore is produced by uniformly mixing and sintering, so that the oily sludge in a steel mill is treated harmlessly, and the resource utilization is realized;
wherein the proportion of the lime is 4-6%; controlling the diameter size of the granulated oily sludge particles within the range of 5-20 mm; the temperature of the high-temperature molten salt flowing in the jacket of each stage of pyrolysis kiln is controlled within the range of 350-480 ℃;
the temperature of the deep pyrolysis is controlled within the range of 400-500 ℃; the time of the deep pyrolysis is controlled within the range of 30-40 min;
the high-temperature molten salt enters from an external heating jacket at a middle temperature section of the multistage pyrolysis kiln system through a pipeline, then sequentially flows through a low-temperature section spiral kiln jacket and a preheating section spiral kiln jacket, and sludge particle materials in an inner cylinder of the spiral kiln are heated or preheated in a heat conduction mode, so that the whole body of the spiral kiln body is heated, the preheating and temperature rising speed of the oily sludge is improved, and the total pyrolysis energy consumption is saved;
the sludge particles pass through a preheating section, a low-temperature section and a medium-temperature section of the multistage pyrolysis kiln system, the temperature is gradually increased, water evaporation occurs in the preheating section of the pyrolysis kiln, and water evaporation and grease decomposition occur in the low-temperature section and the medium-temperature section of the pyrolysis kiln.
2. The method for resource utilization of oily sludge in a steel and iron plant according to claim 1, wherein the heating mode of external heating of the high-temperature molten salt comprises that each stage of spiral heating kiln adopts a sleeve type double-layer structure, and the high-temperature molten salt circularly flowing in an outer sleeve of the pyrolysis kiln heats sludge particle pellet materials in an inner sleeve of each stage of pyrolysis kiln; the flow direction of the high-temperature molten salt is opposite to that of the sludge particle pellet material.
3. The method for resource utilization of oily sludge in a steel plant according to claim 1, wherein the molten salt heating system comprises a molten salt heating furnace; the molten salt heating furnace adopts pyrolysis gas/noncondensable gas containing oily sludge as fuel and blast furnace gas of a steel mill as auxiliary fuel gas; dust-containing gas generated during pyrolysis of the oil-containing sludge enters an oil-gas separator after dust removal, oil and pyrolysis gas/non-condensable gas are separated, and the pyrolysis gas/non-condensable gas enters a gas storage cabinet; and mixing the pyrolysis gas/non-condensable gas in the gas storage cabinet with blast furnace gas, and supplying the gas to a gas burner of the molten salt heating furnace for combustion according to the operating process requirements and conditions of the molten salt heating furnace.
4. The method for recycling oily sludge in a steel and iron plant according to claim 1, wherein the pyrolysis gas is desulfurized by adding lime during the pyrolysis treatment of the sludge particles.
5. A device for resource utilization of oily sludge in a steel plant by adopting the method of claim 1, which is characterized in that:
the device at least comprises a mixer, a spiral feeder, a multi-stage spiral pyrolysis kiln system, a rotary hearth furnace, a pyrolysis oil gas leading-out and separating system, a spiral discharging machine and a storage bin which are connected in sequence;
the mixer and the screw feeder are used for mixing the oily sludge with lime in proportion, and uniformly mixing and granulating the mixture;
the multi-stage spiral pyrolysis kiln system is used for preheating and heating the oily sludge to realize water evaporation and grease decomposition;
the rotary hearth furnace is provided with a microwave generator and an electric control system and is used for further carrying out grease pyrolysis on the oily sludge so as to realize the final deep pyrolysis process of the oily sludge;
the molten salt heating circulation system comprises a molten salt heating furnace, a molten salt circulating pump, a molten salt melting tank and a molten salt circulating pipeline; the molten salt in the melting tank is sent into a molten salt heating furnace by a molten salt circulating pump to be heated, and is heated and melted into high-temperature molten salt fluid which is then conveyed to a pyrolysis kiln system; the high-temperature molten salt fluid flows to the preheating section pyrolysis kiln jacket from the middle-temperature section pyrolysis kiln jacket and the low-temperature section pyrolysis kiln jacket in sequence under the driving of the molten salt circulating pump, and finally flows back to the molten salt melting tank through a pipeline;
the pyrolysis oil gas leading-out and separating system is used for leading out and removing dust of high-temperature oil gas mixture containing dust, water vapor and gaseous oil mist generated by water evaporation and grease pyrolysis in the oil-containing sludge in the rotary hearth furnace and the low-temperature section and the medium-temperature section pyrolysis kiln; after dust removal, the collected dust returns to a sludge storage bin for retreatment; the high-temperature oil gas enters a spraying oil catching device, oil products and non-condensable gas are separated after spraying and cooling, the mixture of oil and water is subjected to oil-water separation through an oil-gas separation tower, oil products are recovered, and the non-condensable gas enters a gas storage cabinet; the non-condensable gas entering the gas storage cabinet is mixed with blast furnace gas of the iron and steel plant and sent into a molten salt heating furnace to heat molten salt
The microwave generator comprises microwave generator magnetrons, at least 2 microwave generator magnetrons are connected in series to form a plurality of groups of microwave generators, each group of microwave generators is arranged above a grate plate of the rotary hearth furnace, each group can be independently started and stopped, and microwave heating power is controlled according to the temperature of sludge pellets discharged by the spiral heating kiln at the middle temperature section and the temperature requirement of pellets in the rotary hearth furnace so as to flexibly control and adjust the pyrolysis temperature;
the microwave generator magnetrons are connected in series by adopting 3 groups and are arranged in 3-4 groups, are uniformly distributed above a grate plate of the rotary hearth furnace, and directly act on the oily sludge material through the metal waveguide, so that the oily sludge material on the cross section of the grate is integrally uniformly and quickly heated; after pyrolysis treatment at 400-500 ℃ for 30-40min, the organic grease in the pellets is also fully decomposed, and the oil removal process of deep pyrolysis is completed.
6. The apparatus for resource utilization of oily sludge of steel and iron works according to claim 5, wherein said multi-stage spiral pyrolysis kiln system is composed of 2-4 stages of spiral heating kilns; all the spiral heating kilns adopt a sleeve type structure, the outer surface of the spiral heating kiln is covered with a heat insulation material, and the inner cylinder is provided with a shaftless spiral which is driven by a motor to drive the oil-containing sludge to turn over and move.
7. The apparatus as claimed in claim 5, wherein an inlet for hot waste gas is provided at the end of the preheating section pyrolysis kiln, and the hot waste gas of 400-500 ℃ generated by the combustion of the fuel gas in the molten salt heating furnace is mixed with air to cool to below 250 ℃ and enters from the inlet to transfer heat in the form of gas-solid convection to the sludge and take away moisture evaporated from the surface.
8. The apparatus for resource utilization of oily sludge in iron and steel plants as claimed in claim 5, wherein the inner cylinders of the low-temperature section and the medium-temperature section pyrolysis kilns and the top of the rotary hearth furnace are provided with an exhaust hole, and the exhaust hole is connected with the oil gas exhaust main pipe through an exhaust pipeline;
the oil gas discharge main pipe is connected with the dust remover;
each exhaust branch pipe and each exhaust main pipe are coated with heat insulation cotton or electric tracing for heat preservation;
hot flue gas coil pipes are arranged on a section of exhaust main pipe close to the dust remover and a lower cone of the dust remover, and 250-300 ℃ hot waste gas generated by mixing waste gas combusted by the molten salt heating furnace and part of cold air is added is introduced to carry out external heating and heat preservation, so that the temperature of oil gas volatilized by sludge pyrolysis is not lower than 160 ℃, and oil substances are prevented from being separated out to block pipelines and the dust remover;
the hot waste gas passing through the hot flue gas coil and the water gas discharged from the preheating section heating kiln are pumped out by an induced draft fan and discharged to atmosphere.
9. The apparatus as claimed in claim 5, wherein two gate valves are respectively disposed at the inlet of the pyrolysis kiln at the preheating section and the outlet of the discharge hopper from the rotary hearth furnace, and the two gate valves are controlled in an interlocking manner to prevent air from entering the rotary hearth furnace and the inner cylinder of the spiral heating kiln during feeding, discharging and stopping, thereby preventing oil gas combustion.
10. The apparatus for resource utilization of oily sludge of steel and iron plants according to claim 5, wherein the molten salt heating furnace is a three-pass vertical cylindrical coil gas molten salt heating furnace.
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| CZ2010807A3 (en) * | 2010-11-08 | 2010-12-22 | Key@Group@Holding@@s@r@o | Organic waste treatment process, organic waste treatment device and use of treated products |
| CN104962300B (en) * | 2015-06-24 | 2018-03-13 | 南京三乐微波技术发展有限公司 | Coal microwave destructive distillation equipment and its coal microwave destructive distillation processing method |
| CN108793650B (en) * | 2017-04-26 | 2021-05-14 | 宝山钢铁股份有限公司 | Treatment method of steel rolling oily sludge |
| CN107098560A (en) * | 2017-06-19 | 2017-08-29 | 重庆航天机电设计院 | Sludge, greasy dirt are combined pyrolysis system |
| CN210085224U (en) * | 2019-04-29 | 2020-02-18 | 北京云水浩瑞环境科技有限公司 | Vertical reactor for fused salt pyrolysis sludge and system with vertical reactor for treating sludge |
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