CN110484300B

CN110484300B - Soil heavy metal restoration plant heat treatment device

Info

Publication number: CN110484300B
Application number: CN201910758147.XA
Authority: CN
Inventors: 金保昇; 王晓佳; 谌通
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2021-03-19
Anticipated expiration: 2039-08-16
Also published as: CN110484300A

Abstract

The invention discloses a plant heat treatment device for repairing heavy metals in soil, which is formed by coupling a medium-temperature gasification reactor and a high-temperature chemical-looping reactor, wherein the high-temperature chemical-looping reactor comprises a chemical-looping reduction reactor, a chemical-looping air reactor, a primary inertial separator, a secondary cyclone separator, a primary return pipe and a secondary down pipe; the medium-temperature gasification reactor is communicated with the chemical chain reduction reactor and the biomass spiral feeder; the chemical-looping reduction reactor is connected with a chemical-looping oxygen carrier feeder, the outlet of the chemical-looping reduction reactor is connected with a primary inertial separator and a secondary cyclone separator, the primary inertial separator is communicated with a primary downcomer, the other end of the primary downcomer is communicated with the chemical-looping air reactor, the secondary cyclone separator is communicated with a secondary downcomer, and the secondary downcomer is communicated with the medium-temperature gasification reactor. The invention realizes the cascade utilization of energy, the reformation and quality improvement of gasification products and the resource utilization of soil heavy metal restoration plants.

Description

Soil heavy metal restoration plant heat treatment device

Technical Field

The invention relates to a heat treatment device for repairing plants in the field of energy and environmental protection, in particular to a heat treatment device for repairing plants by heavy metal in soil.

Background

Along with the large-area popularization and application of the plant restoration technology, the problem of post-partum treatment of the restored plants is brought forward. If a proper postpartum disposal device is not developed, the enriched heavy metal can be returned to the environment again, so that the waste of manpower, material resources and financial resources can be caused, and the secondary pollution to the environment can be generated.

The disposal of the restoration plants mainly comprises compressed landfill, incineration, composting, liquid phase extraction and pyrolysis. The technologies develop for years, the technical route is mature, but some problems exist. The compression landfill treatment mode is simple, the equipment cost is low, secondary pollution is easy to generate, and a large amount of precious land resources are occupied; the reduction of the repaired plants can be realized by the incineration technology, but the incineration device is expensive and is easy to generate atmospheric pollutants such as dioxin, NOx and the like; the composting treatment requires simple devices and low cost, but has a long period and risks secondary pollution; although the heavy metals in the plants can be recovered by liquid phase extraction treatment to achieve the purpose of recycling, the heavy metals are difficult to be used in industrial production in a large scale and have higher cost; the pyrolysis treatment and restoration of the plant can realize the volume reduction rate of more than 90 percent and obtain the combustible gas or the bio-oil, but the requirement on pyrolysis equipment is higher and the large-scale operation is difficult to realize.

In essence, the repair plant belongs to one of biomass, so that the chemical chain gasification treatment by taking the repair plant as fuel has technical feasibility. However, compared to the main goal of maximizing resource utilization in the conventional biomass fuel chemical-looping gasification, the restoration of the phytochemical-looping gasification not only realizes the effective utilization of resources, but also more importantly realizes the harmless volume reduction treatment of heavy metal-containing plants. The treatment of heavy metal restoration plants by a chemical chain process is only reported, and different requirements and challenges are brought to the chemical chain gasification process:

(1) the enrichment temperature of the bottom slag of the heavy metal is not matched with the reaction temperature of the oxygen carrier. The optimal temperature for enriching the heavy metal to the bottom slag does not exceed 700 ℃, which is lower than the requirement that the reaction temperature of the oxygen carrier and the fuel gas in the chemical chain reduction reactor is 800-950 ℃. Therefore, the traditional chemical chain gasification mode is not beneficial to the enrichment of heavy metal to bottom slag, and further influences the recovery rate of the heavy metal.

(2) The migration and transformation rules of heavy metals under the chemical-looping gasification atmosphere are complex. The restoration phytochemistry chain is directly gasified, the process comprises a first-stage gasification reaction of fuel and a gasification agent and a second-stage gasification reaction of a gasification product and an oxygen carrier, the reaction atmosphere is richer, the reaction process is more variable, the heavy metal migration and conversion mechanism is further complicated, and the heavy metal is easy to escape to the environment along with smoke and fly ash.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the technical problems, the invention provides a soil heavy metal restoration plant heat treatment device, which couples medium-temperature gasification to the front end of a high-temperature chemical chain, thereby realizing the cascade utilization of energy and the reforming and quality improvement of combustible gas through two-stage gasification; particularly, the coordination matching between the plant gasification reaction temperature and the heavy metal bottom slag enrichment temperature is achieved through medium-high temperature two-stage gasification.

The technical scheme is as follows: the invention relates to a heat treatment device for soil heavy metal restoration plants, which is formed by coupling a medium-temperature gasification reactor and a high-temperature chemical-looping reactor, wherein the high-temperature chemical-looping reactor comprises a chemical-looping reduction reactor, a chemical-looping air reactor, a primary inertial separator, a secondary cyclone separator, a primary return pipe and a secondary downcomer; the top end of the medium-temperature gasification reactor is communicated with the chemical chain reduction reactor, and the bottom of the medium-temperature gasification reactor is connected with a biomass spiral feeder; the bottom of the chemical-looping reduction reactor is connected with a chemical-looping oxygen carrier feeder, the outlet of the chemical-looping reduction reactor is sequentially connected with a primary inertial separator and a secondary cyclone separator, the primary inertial separator is communicated with a primary descending pipe, the other end of the primary descending pipe is communicated with a chemical-looping air reactor, the chemical-looping air reactor is communicated with the chemical-looping reduction reactor through a primary return pipe, the primary return pipe is provided with a primary return isolator, the secondary cyclone separator is communicated with a secondary descending pipe, and the secondary descending pipe is communicated with the medium-temperature gasification reactor.

The chemical chain reduction reactor is a combined structure of a turbulent fluidized bed and a fast fluidized bed.

The primary downcomer, the primary return pipe, the primary return isolator, the turbulent fluidized bed, the fast fluidized bed, the primary inertial separator and the primary downcomer form a primary oxygen carrier return circulation.

The medium temperature gasification reactor, the turbulent fluidized bed, the fast fluidized bed, the first-stage inertia separator, the second-stage cyclone separator, the second-stage downcomer and the second-stage J-shaped material returning valve form a second-stage repair plant material returning circulation.

The gasifying agent introduced to the bottom of the medium-temperature gasification reactor is water vapor and a small amount of oxygen, and the repaired plant forming material reacts with the gasifying agent to generate rough combustible gas CO and H₂、CH₄、CO₂、C₂H₆。

Oxygen carrier particles entering from a turbulent fluidized bed at the bottom of the chemical chain reduction reactor are contacted with the rough combustible gas, the oxygen carrier particles perform secondary gasification reforming on the rough combustible gas by releasing lattice oxygen, and simultaneously, heavy metals are solidified and adsorbed, and secondary trapping of heavy metals contained in the restoration plants is completed in cooperation with bottom slag enrichment.

The separation system composed of a primary inertia separator and a secondary cyclone separator selectively separates according to the difference between particle density and particle size, the coarse oxygen carrier is firstly separated by the primary inertia separator, enters a chemical-looping air reactor for regeneration, and is sent to a chemical-looping reduction reactor for continuous reaction by a primary return pipe and a primary return isolator; and the fine carbon residue particles are separated in a secondary cyclone separator and are sent into the medium-temperature gasification reactor through a secondary return pipe and a secondary return J-shaped valve.

The reaction temperature in the medium-temperature gasification reactor is 600-700 ℃. The reduction reaction temperature of the crude combustible gas and the oxygen carrier particles in the chemical chain reduction reactor is 800-950 ℃.

The working principle is as follows: the heat treatment device is formed by coupling a medium-temperature gasification reactor and a high-temperature chemical-looping reactor; the medium-temperature gasification reactor is in a bubbling fluidized bed structure; the high-temperature chemical-looping reactor comprises a chemical-looping reduction reactor, a chemical-looping air reactor, a two-stage separation system and a two-stage material returning device, wherein the chemical-looping air reactor is of a moving bed structure, and the two-stage separation system is a combination of a first-stage inertial separator and a second-stage cyclone separator. The medium-temperature gasification reactor is controlled to be in medium-temperature atmosphere, so that the first-stage gasification of the repaired plant is realized to obtain rough combustible gas, and most heavy metals are ensured to migrate and solidify to residues; the chemical chain reduction reactor is in high-temperature atmosphere, secondary gasification reforming of the crude combustible gas is realized by using lattice oxygen of the oxygen carrier, the oxygen carrier is used for solidifying and adsorbing heavy metals, and effective collection of heavy metals of the restoration plants is completed in cooperation with bottom slag enrichment; realizing the oxidation regeneration of the oxygen loss carrier in the chemical-looping air reactor; the separator and the material returning device realize the directional separation among combustible gas, oxygen carrier particles and carbon residue particles and the recycling of the oxygen carrier and the carbon residue particles.

According to the invention, medium-temperature gasification is coupled to the front end of a high-temperature chemical chain, so that the cascade utilization of energy and the reforming and quality improvement of a gasification product are realized, high-quality synthesis gas is obtained, the resource utilization of soil heavy metal restoration plants is realized, the double treatment of heavy metals of the restoration plants in the heat treatment process is realized, the risk of the heavy metals entering the environment in the heat treatment process is effectively reduced, and the harmless treatment is realized.

Meanwhile, the cascade utilization of energy and the reformation and quality improvement of combustible gas are realized through two-stage reaction, the coordination and matching between the repair plant gasification reaction temperature and the heavy metal bottom slag enrichment temperature are realized, and the directional migration of heavy metals mainly based on slag enrichment is realized; the oxygen carrier is modified to realize the synergistic adsorption of the oxygen carrier on heavy metals, and the heavy metal adsorption and solidification with the oxygen carrier adsorption as an auxiliary are realized, so that ideal energy utilization rate and heavy metal recovery rate are obtained, and the postpartum restoration plants are subjected to harmless and recycling treatment.

Has the advantages that: compared with the prior art, the invention has the following technical effects:

(1) in the two-stage heat treatment device for the soil heavy metal restoration plants, the coupling of medium-temperature gasification and a high-temperature chemical chain realizes the cascade utilization of energy and the reforming and quality improvement of gasification products, obtains high-quality synthesis gas, and realizes the resource utilization of the soil heavy metal restoration plants.

(2) The device couples medium-temperature gasification and high-temperature chemical chains, realizes the directional migration and transformation of heavy metals mainly based on slag enrichment and assisted by oxygen carrier adsorption, and thus achieves the purpose of harmless volume reduction of heavy metals of restoration plants.

(3) In the invention, through scientific material screening and advanced modification technology combined, the oxygen carrier is added with a new role of heavy metal high-temperature adsorbent, so that the oxygen carrier can carry out synergistic adsorption on heavy metal of a repairing plant while maintaining the reaction performance, thereby realizing the multifunctional expansion of the oxygen carrier.

Drawings

FIG. 1 is a heat treatment apparatus for a prosthetic plant according to the present invention.

Detailed Description

As shown in FIG. 1, the heat treatment device for repairing plants of the present invention has the following specific connection modes: the top end of the medium-temperature gasification reactor 1 is communicated with the chemical-looping reduction reactor 3, the side wall of the medium-temperature gasification reactor close to the bottom is connected with a biomass spiral feeder 15, and the side wall of the chemical-looping reduction reactor 3 close to the bottom is connected with a chemical-looping oxygen carrier feeder 16; the outlet of the chemical chain reduction reactor 3 is sequentially connected with a first-stage inertial separator 6 and a second-stage cyclone separator 12, the first-stage inertial separator 6 is communicated with a first-stage descending pipe 7, the other end of the first-stage descending pipe 7 is communicated with a chemical chain air reactor 8, the chemical chain air reactor 8 is communicated with the chemical chain reduction reactor 3 through a first-stage return pipe 10, the first-stage return pipe is provided with a first-stage return separator 11, the second-stage cyclone separator 12 is communicated with a second-stage descending pipe 13, and the other end of the second-stage descending pipe is communicated with the medium-temperature gasification reactor 1 through a second-stage return J-shaped valve 14.

The specific setting steps of the heat treatment device for repairing plants are as follows:

(1) the bottom end of the medium-temperature gasification reactor 1 is provided with an air distribution plate, and a gasification agent A is blown into the medium-temperature gasification reactor 1 through the air distribution plate, wherein the gasification agent A is water vapor and a small amount of oxygen. On the side wall of the bottom end of the medium-temperature gasification reactor 1, a biomass screw feeder 15 and a secondary downcomer 13 are respectively connected. The second-stage downcomer 13 is used for returning the carbon residue particles i, the repair plant forming material g and the large-particle inert bed material f are fluidized in a bubbling manner under the fluidization of the gasification agent A in the medium-temperature gasification reactor 1, and a dense-phase region is formed at the bottom end of the medium-temperature gasification reactor 1. The temperature of the medium temperature gasification reactor 1 is controlled between 600 ℃ and 700 ℃, the repair plant forming material g reacts with the gasifying agent A to generate rough combustible gas CO and H₂、CH₄、CO₂And C₂H₆And the majority of heavy metals migrate and enrich to the residue, and a small part of heavy metals and carbon residue particles i enter the high-temperature chemical chain reactor 2 under the carrying of gas.

(2) In the turbulent fluidized bed 4 at the lower part of the chemical chain reduction reactor 3, an oxygen carrier h enters from a primary return pipe 10 or is supplemented from a chemical chain oxygen carrier feeder 16, contacts with the rough combustible gas at 800-950 ℃, releases lattice oxygen to realize secondary gasification reforming of the rough combustible gas, simultaneously realizes solidification adsorption of heavy metals, and completes secondary trapping of heavy metals of the restoration plants in cooperation with bottom slag enrichment.

(3) At the outlet of the fast fluidized bed 5 at the upper end of the chemical-looping reduction reactor 3, the oxygen-loss oxygen carrier particles h and carbon residue particles i after reaction are taken out by flue gas and enter a primary inertial separator 6, most of the oxygen-loss oxygen carrier particles h are separated to a primary downcomer 7 and enter a chemical-looping air reactor 8 due to the large particle size of the oxygen carrier, and part of small-particle oxygen-loss oxygen carrier and fine carbon residue particles are carried by the flue gas to pass through the primary inertial separator 6 and enter a secondary cyclone separator 12.

(4) In the chemical chain air reactor 8, the oxygen loss and carrier h separated by the first-stage inertial separator 6 carries out an oxygen carrying reaction, which specifically comprises the following steps: the oxygen loss oxygen carrier h enters from the top of the chemical-looping air reactor 8, the air B is blown from the lower part of the air reactor 8, the oxygen loss oxygen carrier h and the air B are in contact to generate an oxidation-reduction reaction, oxygen loss oxygen carrier particles h are oxidized and regenerated by the air B, and the reacted tail gas D is discharged from an outlet 9 at the upper end of the chemical-looping air reactor 8. The regenerated oxygen carrier overflows from the chemical chain air reactor 8, enters a primary return pipe 10, then enters the turbulent fluidized bed 4 through a primary return isolator 11 and continuously participates in the chemical chain reaction. The primary downcomer 7, the primary return pipe 10, the primary return isolator 11, the turbulent fluidized bed 4, the fast fluidized bed 5, the primary inertial separator 6 and the primary downcomer 7 form a primary oxygen carrier return circulation.

(5) In the secondary cyclone separator 12, a small amount of oxygen-loss oxygen carrier particles h and carbon residue particles i in the flue gas are separated and then enter a secondary downcomer 13 and a secondary J-shaped return valve 14 in sequence, and return to the medium-temperature gasification reactor 1 under the blowing of steam C for secondary reaction. The fuel circularly moves among the medium-temperature gasification reactor 1, the turbulent fluidized bed 4, the fast fluidized bed 5, the primary inertial separator 6, the secondary cyclone separator 12, the secondary downcomer 13 and the secondary J-shaped material returning valve 14 to form secondary restoration plant material returning circulation.

(6) At the outlet of the secondary cyclone 12, CH is obtained₄CO and H₂And a part of heavy metals absorbed by the restoration plants are enriched to the bottom slag, and the other part of heavy metals are absorbed and solidified by the oxygen carrier, so that the reclamation and harmless treatment of the restoration plants are completed.

The reaction system comprises restoration plant molding materials g with different particle sizes, inert bed materials f, carbon residue particles i and oxygen loss and carrier particles h; wherein the repairing plant forming material g is a strip material and is sent into the medium-temperature gasification reactor 1 through a biomass screw feeder 15; the inert bed material f is large-size coarse particles, and is fluidized only at the bottom of the medium-temperature gasification reactor 1 to form a dense-phase zone; the inert bed material and the molded material of the repair plant are in bubbling fluidization under the fluidization action of the gasification agent, so that the full pyrolysis of the repair plant is facilitated, the rough combustible gas is obtained, and meanwhile, heavy metals are enriched to ash; the carbon residue particles i are small-sized fine particles, are widely distributed in the medium-temperature gasification reactor 1, are carried to the high-temperature chemical-looping reactor 2 by airflow to continuously participate in chemical-looping gasification reaction, and finally, the unreacted part continuously enters the secondary cyclone separator 12 through the primary inertial separator 6, is separated in the secondary cyclone separator and returns to the medium-temperature gasification reactor 1 to continue reaction; the oxygen carrier particles h are small particles with medium size, only move upwards after entering the bottom of the turbulent fluidized bed 4, do not fall into the medium-temperature gasification reactor 1, are not contacted with inert bed materials f of coarse particles, can be effectively separated into the chemical chain air reactor 8 by the primary inertia separator 6, and then return to the bottom of the turbulent fluidized bed 4 through the primary return pipe 10 and the primary return isolator 11 to continuously participate in the chemical chain gasification reaction.

Claims

1. The utility model provides a soil heavy metal restores vegetation heat treatment device which characterized in that: the device is formed by coupling a medium-temperature gasification reactor (1) and a high-temperature chemical-looping reactor (2), wherein the high-temperature chemical-looping reactor (2) comprises a chemical-looping reduction reactor (3), a chemical-looping air reactor (8), a primary inertial separator (6), a secondary cyclone separator (12), a primary return pipe (10) and a secondary downcomer (13); the top end of the medium-temperature gasification reactor (1) is communicated with the chemical chain reduction reactor (3), and the bottom of the medium-temperature gasification reactor is connected with a biomass spiral feeder (15); the bottom of the chemical chain reduction reactor (3) is connected with a chemical chain oxygen carrier feeder (16), the outlet of the chemical chain reduction reactor (3) is sequentially connected with a primary inertial separator (6) and a secondary cyclone separator (12), the primary inertial separator (6) is communicated with a primary downcomer (7), the other end of the primary downcomer (7) is communicated with a chemical chain air reactor (8), the chemical chain air reactor and the chemical chain reduction reactor are communicated through a primary return pipe (10), the primary return pipe is provided with a primary return separator (11), the secondary cyclone separator is communicated with a secondary downcomer (13), and the secondary downcomer is communicated with a medium-temperature gasification reactor.

2. The soil heavy metal restoration plant heat treatment device of claim 1, wherein: the chemical chain reduction reactor (3) is a combined structure of a turbulent fluidized bed (4) and a fast fluidized bed (5).

3. The soil heavy metal restoration plant heat treatment device of claim 2, wherein: the primary downcomer (7), the primary return pipe (10), the primary return isolator (11), the turbulent fluidized bed (4), the fast fluidized bed (5), the primary inertial separator (6) and the primary downcomer (7) form a primary oxygen carrier return circulation.

4. The soil heavy metal restoration plant heat treatment device of claim 2, wherein: the medium-temperature gasification reactor (1), the turbulent fluidized bed (4), the fast fluidized bed (5), the primary inertial separator (6), the secondary cyclone separator (12), the secondary downcomer (13) and the secondary J-shaped return valve (14) form a secondary restoration plant return circulation.

5. The soil heavy metal restoration plant heat treatment device of claim 1, wherein: the gasifying agent (A) introduced to the bottom of the medium-temperature gasification reactor (1) is water vapor and a small amount of oxygen, and the repaired plant forming material reacts with the gasifying agent to generate rough combustible gas CO and H₂、CH₄、CO₂、C₂H₆。

6. The soil heavy metal restoration plant heat treatment device of claim 2, wherein: oxygen carrier particles (h) entering from the turbulent fluidized bed (4) at the bottom of the chemical chain reduction reactor (3) are contacted with the crude combustible gas, the oxygen carrier particles (h) carry out secondary gasification reforming on the crude combustible gas by releasing lattice oxygen, and simultaneously, the heavy metals are solidified and adsorbed, and secondary trapping of heavy metals contained in the restoration plants is completed in cooperation with bottom slag enrichment.

7. The soil heavy metal restoration plant heat treatment device of claim 1, wherein: the coarse oxygen carrier is firstly separated by a first-stage inertia separator (6), enters a chemical-looping air reactor (8) for regeneration, and is sent into a chemical-looping reduction reactor (3) for continuous reaction through a first-stage return pipe (10) and a first-stage return material isolator (11); and the fine carbon residue particles (i) are separated in a secondary cyclone separator (12) and are sent into the medium-temperature gasification reactor (1) through a secondary return pipe (13) and a secondary return J-shaped valve (14).

8. The soil heavy metal restoration plant heat treatment device of claim 1, wherein: the reaction temperature in the medium-temperature gasification reactor (1) is 600-700 ℃.

9. The soil heavy metal remediation phytothermal treatment apparatus of any one of claims 1 to 8, wherein: the reduction reaction temperature of the crude combustible gas and the oxygen carrier particles in the chemical chain reduction reactor (3) is 800-950 ℃.