CN109108044B

CN109108044B - Inside and outside circulation combined three-phase double-bed coupled pickling system and method

Info

Publication number: CN109108044B
Application number: CN201710491499.4A
Authority: CN
Inventors: 代建军; 张贺东; 高作鹏; 康秦豪; 敖文雅; 付洁; 毛笑; 刘洋; 冉春梅
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2017-06-24
Filing date: 2017-06-24
Publication date: 2023-06-30
Anticipated expiration: 2037-06-24
Also published as: CN109108044A

Abstract

The invention relates to an inside and outside circulation combined three-phase double-bed coupled pickling system and method. The contaminated solid and the pickling liquid are mixed in the pickling tower, the pickling liquid enters a plurality of liquid inlets of the pickling tower, and the mixing and distribution of the gas, liquid and solid phases of the pickling tower are greatly promoted, and the mass transfer efficiency and the pickling effect are improved through the rotational flow movement of the liquid, the design of a solid sedimentation section and a solid concentration section, the use of an internal circulation cylinder and the external circulation of a cyclone separator and the application of an air floatation and screw stirring, mixing, conveying and extrusion mechanism; the screw conveyor conveys the concentrated solids to the water washing unit, after liquid-solid separation, the solids enter the dryer for drying treatment, and the liquid returns to the pickling tower for recycling; the improvement of the structure of the pickling tower, the use of the internal and external circulation of the pickling liquid and the optimization of the process route and parameters improve the gas-liquid-solid three-phase distribution and the gas-liquid-solid mixing uniformity, improve the pickling efficiency and the pickling effect, save the consumption of the pickling liquid and improve the system economy.

Description

Inside and outside circulation combined three-phase double-bed coupled pickling system and method

Technical Field

The invention relates to an inside and outside circulation combined three-phase double-bed coupled pickling system and method, in particular to a system and method for pickling and cleaning polluted soil and other polluted solids.

Background

Along with the rapid development of the economy and the acceleration of the urban and industrialized processes in China, the pollution problem is also becoming serious. In the early twenty-first century, china has strictly limited and required enterprises and has closed or shifted a large number of enterprises in recent years, and the enterprises relate to various industries such as metallurgy, chemical industry, electric power and the like, so that a large number of pollution sites are left in place on factories, serious damage is caused to soil and water quality, and serious influence is brought to the life of local residents.

The contaminants can be classified into organic contaminants, inorganic contaminants, and complex contaminants. According to the national pollution condition investigation gazette, the overall environmental condition of the country is not optimistic, the soil environmental problem of the industrial and mining abandoned land is prominent, and the soil environmental quality of the cultivated land is candid. The soil is overstandard by 16.1% nationwide, and the inorganic contaminant overstandard soil accounts for 82.8% of all detection sites. The pollution distribution is characterized by gradually rising from north to south (from northwest to southwest and from northeast to southwest), and the soil pollution problem of partial areas such as Yangtze river delta, zhujiang delta, northeast old industrial bases and the like is particularly serious. The type of industry and the level of technology determine the type of contaminated site. The pollution sources mainly comprise heavy metal pollution, persistent Organic Pollutants (POPs) pollution, electronic waste pollution, organic petroleum, chemical industry, coking pollution and the like. Soil pollution is generally produced by the transformation of atmospheric and water pollution, and due to the modernization of industry and agriculture, a large amount of chemical waste and pesticides are scattered into the environment, and the pollution area is continuously enlarged by water and soil loss and wind erosion. Meanwhile, industrial and mining enterprises generate a large amount of sludge or waste catalysts of natural minerals each year, and the ecological environment is also seriously harmed. The treatment modes currently considered mainly comprise various physical (such as weather extraction and leaching methods), chemical methods (such as chemical oxidation), heat treatment (such as thermal desorption, microwave thermal restoration and electric heat restoration), biochemistry (such as plant and microorganism restoration) and other methods, and the various methods have respective advantages and also have corresponding disadvantages such as incomplete removal of organic matters or heavy metals, easy secondary pollution and the like, so that the popularization and development of the technologies are severely restricted. At present, a technology or a device for rapidly and efficiently treating and disposing the polluted solids is urgently needed in China so as to reduce or prevent the harm to the environment. The technology or the device can treat polluted solids in situ or ex situ, and the treated clean solids can be safely used without causing secondary pollution to the environment; in addition, various collected toxic and harmful substances can be intensively treated, so that the treatment capacity of the toxic and harmful substances is reduced, the treatment efficiency is improved, the treatment effect is improved, and the method has important practical significance and positive and profound ecological influence on the protection and improvement of soil and water quality.

Disclosure of Invention

The technical scheme for realizing the purpose of the invention is as follows: the method comprises the steps of dividing an upper section and a lower section of a pickling tower, wherein the diameter of a sedimentation section of the upper section of the pickling tower is larger, the diameter of a concentration section of the lower section of the pickling tower is smaller, pickling liquid enters a plurality of liquid inlets of the pickling tower, and solid and pickling liquid are mixed in the sedimentation section of the pickling tower, and through the rotational flow movement of the liquid, the structural design of the solid sedimentation section and the concentration section, the use of an internal circulation cylinder and the external circulation of a cyclone separator and the application of an air floatation and screw stirring, mixing, conveying and extrusion mechanism, the mixing and distribution of the gas, liquid and solid phases of the pickling tower are greatly promoted, and the mass transfer efficiency and the pickling effect are improved; the screw mixing conveyor conveys the concentrated solids to the water washing unit for water washing, the concentrated solids enter the liquid-solid separation unit after water washing, the solids enter the dryer for drying treatment, and after the liquid and the liquid discharged by the screw mixing conveyor are mixed, part of the liquid returns to the pickling tower for recycling.

The pickling system for realizing the combination of internal and external circulation and three-phase double-bed coupling of the method comprises a solid feeding system, a pickling tower and a cyclone separator, wherein a fresh pickling liquid feeding pipe, a pickling liquid mixer, a pickling liquid conveying pump, a blower, a screw mixing conveyor, a water washing unit, a liquid-solid separation unit and a drying unit, the pickling tower comprises a pickling tower sedimentation section with a larger upper diameter and a pickling tower concentration section with a smaller lower diameter, an internal circulation cylinder and a gas distributor are arranged in the pickling tower, the internal circulation cylinder is vertically fixed at the radial center position in the pickling tower, the gas distributor is communicated with the blower through a pipeline pipe, the solid feeding system is communicated with the pickling tower at the upper part of the pickling tower sedimentation section, the solid feeding system adds polluted solid and additive into the pickling tower from the upper part of the pickling tower sedimentation section, the leaching tower is communicated with the cyclone liquid separator, the cyclone liquid separator returns solids to the concentration section of the leaching tower through the solid feed back pipe of the cyclone liquid separator, the cyclone liquid separator conveys a part of liquid to the leaching liquid mixer through the liquid feed back pipe of the cyclone liquid separator at the upper part of the cyclone liquid separator, the concentration section of the leaching tower is communicated with the screw mixing conveyor below the concentration section of the leaching tower, the concentrated solids are extruded and dehydrated by the screw mixing conveyor and conveyed to the water washing unit for water washing, after water washing, the solids enter the liquid-solid separation unit for liquid-solid separation, the solids after the liquid-solid separation enter the drying unit for drying, a part of liquid output from the screw mixing conveyor and the liquid-solid separation unit is returned to the leaching liquid mixer through the liquid collecting pipe, fresh leaching liquid is input to the leaching liquid mixer through the fresh leaching liquid feeding pipe, the liquid in the pickling liquid mixer is respectively conveyed to a settling section of the pickling tower at the upper part of the pickling tower and a concentration section of the pickling tower at the lower part of the pickling tower in a tangential direction through a first liquid inlet and a second liquid inlet by a pickling liquid conveying pump.

The above-mentioned internal and external circulation combination, three-phase double-bed coupled pickling system and method, the first liquid inlet is in the tangential inlet position of the settling section of the pickling tower, the second liquid inlet is in the tangential inlet position of the concentrating section of the pickling tower, the diameter of the settling section of the pickling tower is greater than that of the concentrating section of the pickling tower, the liquid enters the pickling tower from the tangential direction of the settling section of the pickling tower and the concentrating section of the pickling tower respectively, so as to form a swirl motion from top to bottom, the polluted solid and fluid are in vigorous forward flow and backward flow in the turbulent swirl motion, so that severe liquid-solid interaction is produced, toxic and harmful substances are separated from the polluted solid, so that the solid is subjected to pickling and purification, clean and high-density solid particles are settled in the swirl motion and concentrated in the concentrating section of the pickling tower, the water is carried up to the settling section of the pickling tower in the swirl motion, the liquid-solid separation is continued by the cyclone separator, and the settling section of the pickling tower and the concentrating section of the pickling tower can be respectively provided with 1 or more liquid inlets, and the polluted solid enters the pickling tower is at normal temperature or higher temperature.

According to the inside and outside circulation combined three-phase double-bed coupled pickling system and method, the inner circulation cylinder is vertically fixed at the radial center position inside the pickling tower, the inner walls of the inner circulation cylinder and the pickling tower form a flow passage with the cross section area gradually reduced from top to bottom, the rotational flow motion of pickling liquid and polluted solids occurs in the flow passage with the cross section area gradually reduced from top to bottom, the soaked solids are enriched in the narrow flow passage of the concentration section of the pickling tower under the rotational flow motion and the action of gravity, the water-soluble substances or the substances with smaller density are extruded and dehydrated by the screw mixing conveyor and conveyed to the water washing unit, and the water-soluble substances or the substances with smaller density float to the sedimentation section of the pickling tower, so that the liquid-solid separation is further carried out by the cyclone separator.

According to the inside-outside circulation combined three-phase double-bed coupled pickling system and method, the air blower is communicated with the gas distributor through the pipeline, the gas distributor is arranged in the inner circulation cylinder and at the bottom of the inner circulation cylinder, the gas outlet of the gas distributor is upward, the air bubbles move upward, the components lighter than water in the water phase are air-floated, and the components rise to the sedimentation section of the pickling tower along with the bubbles and enter the cyclone separator along with the water phase to carry out liquid-solid separation, meanwhile, the rising bubbles in the inner circulation cylinder enable the inner circulation cylinder and the inside of the pickling tower to generate circulation, and the rotational flow movement in the pickling tower is combined, so that the turbulence degree of fluid and the mass transfer between the three phases of gas, liquid and solid are promoted, the pickling efficiency is improved, and the pickling effect is improved; the addition of additives (such as a leaching agent, a chelating agent, a flocculating agent or a coagulant, etc.) and the use of an air floatation principle promote the leaching effect and the liquid-solid separation; the air blower can also convey the hot gas to the internal circulation cylinder and the pickling tower through the gas distributor, so that the pollutant removal efficiency is further improved, and the pickling effect is improved.

The inside and outside circulation combined three-phase double-bed coupled pickling system and method are characterized in that a pickling tower concentration section is communicated with a screw mixing conveyor at the lower part, concentrated solids enter the screw mixing conveyor from the pickling tower concentration section, the screw of the screw mixing conveyor extrudes and dewaters the concentrated solids, and extruded water phase is discharged through small holes below the tail end of the extrusion section of the screw mixing conveyor.

The solid feeding system adds polluted solid and additive (such as various flocculating agents or coagulants and the like) into the pickling tower from the upper part of a settling section of the pickling tower, fresh pickling liquid is input into a pickling liquid mixer through a fresh pickling liquid feeding pipe and is mixed with liquid which is circulated and reflowed from the upper part of a cyclone separator and liquid which is circulated and reflowed from a screw mixing conveyor and a liquid-solid separation unit in the pickling liquid mixer, the mixed liquid is respectively conveyed into the settling section of the pickling tower with larger diameter and a concentrating section of the pickling tower with smaller diameter in the tangential direction through a liquid inlet I and a liquid inlet I by a pickling liquid conveying pump, so that rotational flow movement taking an inner circulating cylinder as a center is formed, and a flow channel of rotational flow movement is gradually narrowed from top to bottom; the air blower blows air or hot air into the bottom of the inner circulation cylinder through the air distributor, the air bubble is light in weight, and the bottom of the inner circulation cylinder moves upwards to air float the pollutant with small density and send the pollutant to the sedimentation section of the pickling tower; the combination of the rotational flow movement and the internal circulation movement greatly promotes the turbulence degree of the fluid and the mixing and mass transfer of the gas, the liquid and the solid, improves the pickling efficiency and improves the solid pickling effect. The water phase, the light-density pollutants and some entrained particles are subjected to liquid-solid separation by a hydrocyclone, the high-density particles are returned to a concentration section of the pickling tower by a solid return pipe of the hydrocyclone, one part of the light-density water phase and the entrained matters are returned to a pickling liquid mixer, and the other part of the light-density water phase and the entrained matters are sent to a downstream unit for further treatment. The solid enriched at the bottom of the concentrating section of the leaching tower is extruded and dehydrated by a screw mixing conveyor and is conveyed to a washing unit for further washing so as to thoroughly wash toxic and harmful substances, the washed solid enters a liquid-solid separation unit, the solid separated by the liquid-solid separation unit enters a drying unit for drying treatment, and after the liquid separated by the liquid-solid separation unit is mixed with the liquid separated by the screw mixing conveyor, one part of the liquid returns to a leaching solution mixer, and the other part of the liquid enters a downstream unit for further treatment.

The invention has the positive effects that: (1) The pickling tower of the method or the system comprises a settling section of the pickling tower with a larger upper diameter and a concentrating section of the pickling tower with a smaller lower diameter, so that a flow channel which is gradually narrowed from top to bottom is formed; (2) The leaching solution enters the leaching tower in the tangential direction of the sedimentation section and the concentration section of the leaching tower respectively, and forms rotational flow motion taking an inner circulation cylinder as the center in the leaching tower, so that the gas-liquid-solid mixing and mass transfer are promoted; (3) The gas or hot gas is added at the bottom of the inner circulation cylinder, rises in the inner circulation cylinder, floats the pollutant with light density to the sedimentation section of the pickling tower to form the inner circulation of the pickling tower, the pollutant with light density enters the cyclone liquid separator and is discharged from the top of the cyclone liquid separator, and the inner circulation is coupled with the cyclone movement, so that the turbulence degree is greatly improved, the gas-liquid-solid mixing and mass transfer are promoted, the pickling efficiency is improved, and the pickling effect is improved; (4) The water phase discharged by the pickling tower, the light-density pollutants and entrained particles are subjected to liquid-solid separation in the cyclone separator, the heavy-density flow is returned to the concentration section of the pickling tower through the solid feed back pipe of the cyclone separator, a part of the light-density flow is returned to the pickling liquid mixer and further enters the sedimentation section of the pickling tower and the concentration section of the pickling tower respectively in the tangential direction, so that the outer circulation of the pickling tower is formed, and the use of the inner circulation and the outer circulation promotes the gas-liquid-solid mixing and mass transfer, improves the pickling efficiency and improves the pickling effect; (5) The pickling tower and the screw mixing conveyor are coupled to realize the integration of concentration, enrichment, extrusion and dehydration of solids, so that the liquid-solid separation efficiency and the pickling efficiency are improved.

Drawings

In order that the invention may be more readily understood, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, in which

FIG. 1 is a schematic diagram of a pickling system according to the present invention;

wherein:

1 a solid feeding system, 2 a pickling tower, 3 a settling section of the pickling tower, 4 a concentrating section of the pickling tower, 5 an inner circulation cylinder, 6 a gas distributor, 7 a cyclone separator, 8 a cyclone separator solid feed back pipe, 9 a fresh pickling liquid feed pipe, 10 a pickling liquid mixer, 11 a pickling liquid delivery pump, 12 a blower, 13 a first liquid inlet, 14 a second liquid inlet, 15 a cyclone separator liquid feed back pipe, 16 a liquid collecting pipe, 17 a screw mixing conveyor, 18 a water washing unit, 19 a liquid-solid separation unit, 20 a drying unit

Detailed Description

Example 1, see FIG. 1

The example comprises a solid feed system 1, a pickling tower 2, a hydrocyclone 7, a fresh pickling liquid feed pipe 9, a pickling liquid mixer 10, a pickling liquid delivery pump 11, a blower 12, a screw mixing conveyor 17, a water washing unit 18, a liquid-solid separation unit 19, and a drying unit 20. The solid feeding system 1 adds heavy metal contaminated soil, citric acid and lime into the pickling tower 2 from the upper part of the settling section 3 of the pickling tower, nitric acid is input into the pickling liquid mixer 10 from the fresh pickling liquid feeding pipe 9, liquid which is circulated and reflowed from the upper part of the cyclone separator 7 and liquid which is circulated and reflowed from the screw mixing conveyor 17 and the liquid-solid separation unit 19 are mixed with fresh pickling liquid in the pickling liquid mixer 10, the mixed liquid is heated to 90 ℃, and the mixed liquid is respectively conveyed to the settling section 3 of the pickling tower with larger diameter and the concentrating section 4 of the pickling tower with smaller diameter from the tangential direction through the first liquid inlet 13 and the second liquid inlet 14 by the pickling liquid conveying pump 11, so that rotational flow movement taking the inner circulation cylinder 5 as the center is formed, and the flow path of the rotational flow movement is gradually narrowed from top to bottom; the air blower 12 blows air into the bottom of the inner circulation cylinder 5 through the gas distributor 6, the air bubbles have light weight, and the air bubbles move upwards from the bottom of the inner circulation cylinder 5 to air float the pollutant with low density and send the pollutant to the sedimentation section 3 of the pickling tower; the combination of the rotational flow movement and the internal circulation movement greatly promotes the turbulence degree of the fluid and the mixing and mass transfer of the gas, the liquid and the solid, improves the pickling efficiency and improves the solid pickling effect. The aqueous phase, the light-density pollutants and some entrained particles are subjected to liquid-solid separation by a hydrocyclone 7, the high-density particles are returned to the concentration section 4 of the pickling tower by a hydrocyclone solid return pipe 8, one part of the light-density aqueous phase and the entrained matters are returned to a pickling liquid mixer 10, and the other part of the light-density aqueous phase and the entrained matters are sent to a downstream unit for further treatment. The solid enriched at the bottom of the concentrating section 4 of the leaching tower is extruded and dehydrated by a screw mixing conveyor 17 and is conveyed to a washing unit 18 for further washing to thoroughly wash toxic and harmful substances, the washed solid enters a liquid-solid separation unit 19, the solid separated by the liquid-solid separation unit 19 enters a drying unit 20 for drying treatment, and after the liquid separated by the liquid-solid separation unit 19 is mixed with the liquid separated by the screw mixing conveyor 17, one part of the liquid returns to the leaching solution mixer 10, and the other part of the liquid enters a downstream unit for further treatment.

Example 2, see FIG. 1

The difference between this embodiment and embodiment 1 is that: the solid feed system 1 adds heavy metal contaminated soil, citric acid and polysilicate ferric sulfate to the pickling tower 2 from the upper part of the settling section 3 of the pickling tower, and normal temperature water is fed to the pickling liquid mixer 10 from the fresh pickling liquid feed pipe 9. The other system composition was the same as in example 1.

Example 3, see FIG. 1

The difference between this embodiment and embodiment 1 is that: the solid feeding system 1 adds clay catalyst polluted by organic matters and polysilicic acid flocculant into the pickling tower 2 from the upper part of the settling section 3 of the pickling tower, normal-temperature water is input into a pickling liquid mixer from a fresh pickling liquid feeding pipe 9, and a blower 12 blows hot air at 120 ℃ into the inner circulation cylinder 5 through a gas distributor 6. The other system composition was the same as in example 1.

While the foregoing is directed to embodiments of the present invention, other and further details of the invention may be had by the present invention, it should be understood that the foregoing description is merely illustrative of the present invention and that no limitations are intended to the scope of the invention, except insofar as modifications, equivalents, improvements or modifications are within the spirit and principles of the invention.

Claims

1. The utility model provides a pickling system of inside and outside circulation combination, three-phase double bed coupling, includes solid feed system (1), pickling tower (2), hydrocyclone (7), fresh pickling liquid inlet pipe (9), pickling liquid blender (10), pickling liquid delivery pump (11), air-blower (12), screw rod mixed conveyer (17), washing unit (18), liquid-solid separation unit (19), drying unit (20), its characterized in that: the pickling tower (2) comprises a pickling tower sedimentation section (3) with a larger upper diameter and a pickling tower concentration section (4) with a smaller lower diameter, an inner circulation cylinder (5) and a gas distributor (6) are arranged in the pickling tower (2), the inner circulation cylinder (5) is vertically fixed at the radial center position in the pickling tower (2), the gas distributor (6) is communicated with a blower (12) through a pipeline pipe fitting, the solid feeding system (1) is communicated with the upper part of the pickling tower sedimentation section (3), polluted solid and additive are added into the pickling tower (2) from the upper part of the pickling tower sedimentation section (3), the pickling tower (2) is communicated with a cyclone separator (7), the cyclone separator (7) is communicated with the pickling tower concentration section (4) through a cyclone separator solid return pipe (8) at the upper part, the cyclone separator (7) is communicated with a pickling liquid mixer (10) through a cyclone separator liquid return pipe (15) at the upper part of the cyclone separator, the pickling tower concentration section (4) is communicated with a mixer (17) at the lower part of the cyclone separator, a mixer (17) is communicated with a screw (17) is communicated with a solid-liquid separator (17), a screw (17) is communicated with a solid-liquid separator (19), and a solid-liquid separator (17) is communicated with a screw unit (19 is communicated with a solid-liquid separator unit (17) is communicated with a screw unit (19) A part of liquid output by the liquid-solid separation unit (19) is returned to the leaching liquor mixer (10) through the liquid collecting pipe (16), fresh leaching liquor is input to the leaching liquor mixer (10) through the fresh leaching liquor feeding pipe (9), the liquid in the leaching liquor mixer (10) is respectively conveyed to the leaching tower sedimentation section (3) at the upper part of the leaching tower (2) and the leaching tower concentration section (4) at the lower part of the leaching tower through the first liquid inlet (13) and the second liquid inlet (14) at the tangential inlet position of the leaching tower sedimentation section (3), the diameter of the leaching tower sedimentation section (3) is larger than that of the leaching tower concentration section (4), one or more liquid inlets can be respectively arranged in the leaching tower sedimentation section (3) and the leaching tower concentration section (4), the leaching liquor in the leaching tower (2) is at normal temperature or higher temperature, the first liquid inlet (13) is at the tangential inlet position of the leaching tower sedimentation section (3), the inlet (12) is at the tangential inlet position of the leaching tower sedimentation section (3), the inlet (2) is at the air inlet position of the leaching tower sedimentation section (6), the inlet (6) is at the normal temperature, the air circulation section (6) is at the air circulation section (6), and the air circulation section (6) is at the bottom of the air circulation section (6) is at the normal temperature, and the air circulation section is at the air circulation section (6) is at the air circulation section at the air circulation temperature.

2. A pickling system according to claim 1, characterized in that the inner circulation cylinder (5) is vertically fixed at a radial center position inside the pickling tower (2), and a flow passage with a gradually decreasing cross-sectional area from top to bottom is formed between the outer wall of the inner circulation cylinder (5) and the inner wall of the pickling tower (2).

3. A pickling system according to claim 1, characterized in that the pickling tower concentration section (4) communicates with the screw mixing conveyor (17) at the lower part, the screw of the screw mixing conveyor (17) extrudes concentrated solids for dewatering, and a plurality of holes are arranged below the end of the extrusion section of the screw mixing conveyor (17).

4. A pickling method of a pickling system according to claim 1 is characterized in that the diameter of a settling section (3) of a pickling tower is larger, the diameter of a concentration section (4) of the pickling tower is smaller, pickling liquid enters a plurality of liquid inlets of the pickling tower (2), solids and the pickling liquid are mixed in the settling section (3) of the pickling tower, and the mixing and distribution of gas, liquid and solid phases of the pickling tower (2) are greatly promoted and the mass transfer efficiency and the pickling effect are improved by the rotational flow of the liquid, the design of the solid settling section and the concentration section, the use of an inner circulation cylinder and the outer circulation of a cyclone separator and the application of an air floatation and screw mixed conveying extrusion mechanism; the screw mixing conveyor (17) conveys the concentrated solids to the water washing unit (18) for water washing, the solids enter the drying unit (20) for drying treatment after being separated by the liquid-solid separation unit (19), and part of the liquid is returned to the pickling tower (2) for recycling after being mixed with the liquid discharged by the screw mixing conveyor (17).