CN116159853A - Porous medium combustion type organic matter polluted soil pile heat restoration method and system - Google Patents

Abstract

The invention relates to the field of contaminated soil treatment, and discloses a method and system for thermal restoration of porous media combustion organic matter polluted soil. The method includes: turning on the heating pipe to heat the soil pile, using a gas pumping well to extract the desorbed gas, sending at least part of it into a porous medium combustion tube for combustion, and using the gas pumping well to The soil pile is injected with air so that the pilot material burns in the presence of oxygen; and the oxidizer is added through the tonic well. By adopting the system and method, the polluted soil can be treated more efficiently, the full reuse of the desorbed organic gas can be realized, the energy consumption and the load of the post-processing equipment can be reduced, and it is more environmentally friendly.

Description

Method and system for thermal remediation of porous media combustion organic matter polluted soil

technical field

The invention relates to the field of contaminated soil treatment, in particular to a method and system for thermal restoration of porous media combustion organic matter polluted soil.

Background technique

Due to the rapid development of the petrochemical industry and the wide application of petrochemical products, the problem of soil pollution has become more and more serious. Organic pollutants can destroy soil physical and chemical properties, affect plant growth, crop quality and endanger human health. Therefore, rapid and efficient remediation of organic polluted soil is of great value for the sustainable development of the ecological environment.

Thermal desorption technology is an efficient organic contaminated soil remediation technology. Its basic principle is to heat the contaminated soil above the boiling point of the pollutants, so that the pollutants can be desorbed from the soil and effectively removed. The desorbed pollutants are usually used Exhaust gas is discharged after treatment by the exhaust gas treatment system. The exhaust gas before discharge is generally recovered by waste heat recovery equipment, but the waste heat recovery equipment is complicated, and a large amount of heat will be lost during the heat exchange process, resulting in energy waste. Therefore, there is an urgent need to develop a more efficient and less energy-intensive treatment method for organically polluted soil.

CN215430793U discloses a kind of soil thermal pile restoration device, heats into the heating pipe through the heating assembly, makes the heating pipe heat the heap body to be repaired, and slowly rotates and stirs, so that the organic matter in the soil is heated and evaporated, the device adopts multiple stirring The bump heating tube has high system energy consumption and high processing cost, and the exhaust gas is directly discharged.

CN213763426U discloses a kind of energy-saving and high-efficiency stack type thermal desorption system, and this system reduces floor area and improves soil thermal desorption efficiency by reducing the amount of slope; By using reusable thermal insulation wall and thermal insulation layer, Materials and energy are saved, but the single thermal repair method does not reduce the energy consumption leading to the interior of the pile, and at the same time cannot achieve rapid repair.

The above devices or systems have the disadvantages of high energy consumption, long repair period, and low repair efficiency.

Contents of the invention

The object of the present invention is to overcome the above-mentioned problems existing in the prior art, and to provide a method and system for thermal restoration of porous media combustion-type organic matter-contaminated soil. By using the system and method, the contaminated soil can be treated more efficiently and the soil can be fully removed. organic pollutants, realize the full reuse of the desorbed organic gas, reduce energy consumption and the load of post-processing equipment, and be more environmentally friendly.

In order to achieve the above object, on the one hand, the present invention provides a porous media combustion type organic matter-contaminated soil heap thermal repair method, which is implemented in a system including a main body repair module;

Wherein, the main repair module includes a soil heap to be treated, and the soil heap is sequentially provided with a tonic well, a gas injection well, a porous medium combustion tube and a heating tube from top to bottom;

The tonic well is used to add oxidant to the soil pile; the porous medium combustion tube is filled with the first porous medium, and the porous medium combustion tube is used to burn and release heat to the soil pile; the gas injection well is used to inject air into the soil pile or extract air from the soil The gas extracted and desorbed in the pile; the heating pipe is used to heat the soil pile; the gas injection well is connected with the porous medium combustion pipe, so that the gas extracted by the gas injection well can enter the porous medium combustion pipe for combustion ; An igniting substance is laid around the heating pipe, and the igniting substance is doped with a second porous medium;

The method includes: turning on the heating pipe to heat the soil pile, using a gas pumping well to extract the desorbed gas, sending at least part of it into a porous medium combustion tube for combustion, and using the gas pumping well to The soil pile is injected with air so that the pilot material burns in the presence of oxygen; and the oxidizer is added through the tonic well.

A second aspect of the invention provides a system as described in the first aspect.

The invention realizes the maximum utilization of organic matter and multiple combined restoration modes, has high efficiency and saves energy consumption. Has the following advantages:

(1) Combustion of the ignited substance doped with the second porous medium can make the organic matter in the soil continuously and stably self-combust, the temperature is higher, and the organic pollutants in the soil can be better removed; burning through the porous medium The combustion in the tube not only realizes the full reuse of the desorbed organic gas, but also further increases the temperature in the reactor and reduces the discharge of organic pollutants, thereby reducing the energy consumption and load of post-processing equipment, reducing environmental risks, and achieving green and efficient restoration effects ;

(2) Preferably in the later stage of the treatment, that is, when the desorbed organic gas is not sent to the porous media combustion tube for combustion, the oxidation efficiency of the residual organic pollutants can be effectively improved by coupling the residual heat with the chemical oxidant, which can also reduce the heat Energy consumption required for stack heating, shortening soil remediation time;

(3) A foamed cement layer covering heat insulation is laid on the outside of the pile body, which can effectively prevent energy loss and pollutants from spreading to the external environment. The materials used are environmentally friendly and economical, and have good energy utilization effects.

Description of drawings

Fig. 1 is the front view of the main repair module of a system for realizing thermal restoration of organic-contaminated soil provided by a preferred embodiment of the present invention;

Fig. 2 is a left view of a main repair module of a system for realizing thermal restoration of organic-contaminated soil provided by a preferred embodiment of the present invention.

Explanation of reference signs

1-heating controller, 2-heating pipe, 3-metal heat pipe, 4-ignition material, 5-porous media combustion pipe, 6-gas delivery pipe, 7-valve, 8-gas pumping well, 9-collection Pipeline, 10-Tail gas feedback adjustment optimization device, 11-Water gas separator, 12-Tail water and tail gas treatment components, 13-Pharmaceutical regulator, 14-Tonic well, 15-Rock wool board, 16-Foamed cement layer, 17 - Tonic well branch.

Detailed ways

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

The first aspect of the present invention provides a porous media combustion type organic matter-contaminated soil pile thermal repair method, the method is implemented in a system including a main repair module;

Wherein, the main repair module includes a soil heap to be treated, in which a tonic well 14, a gas injection well 8, a porous medium combustion tube 5 and a heating tube 2 are sequentially arranged from top to bottom;

The tonic well 14 is used to add oxidant to the soil pile; the first porous medium is filled in the porous medium combustion pipe 5, and the porous medium combustion pipe 5 is used for burning and releasing heat to the soil pile; the gas injection well 8 is used to inject heat into the soil pile. Inject air or extract the desorbed gas from the soil pile; the heating pipe 2 is used to heat the soil pile; the gas extraction well 8 is connected with the porous medium combustion pipe 5, so that the gas extracted by the gas injection well 8 , can enter the porous medium combustion tube 5 for combustion; an igniting substance 4 is laid around the heating tube 2, and the igniting substance 4 is doped with a second porous medium;

The method includes: turning on the heating pipe 2 to heat the soil pile, extracting the desorbed gas by using the gas pumping well 8, sending at least part of it into the porous medium combustion tube 5 for combustion, and using the gas pumping The injection well 8 injects air into the soil pile, so that the ignition substance 4 burns in the presence of oxygen;

The inventors of the present invention found in research that according to the above method, the organic pollution in the soil can be desorbed from the soil under heating conditions. After the desorbed gas is extracted, it is sent to the porous medium combustion tube 5 for combustion, which not only recovers the desorbed organic gas, further improves the temperature in the soil pile, reduces the emission of organic pollutants, and also It reduces the energy consumption and load of post-processing equipment, reduces environmental risks, and achieves green restoration effects. The first porous medium filled in the porous medium combustion tube 5 can also better radiate heat into the soil. The combustion of the igniting substance can make the organic gas in the nearby soil burn together, and fully remove the organic pollutants therein, especially the second porous medium doped in it, which can make the combustion more stable and the temperature higher, and can Better removal of organic matter in the soil. The addition of the oxidant makes the coupling of the oxidant and the heating work under the condition of heating, and removes the organic pollutants in the soil more efficiently, and can complete the desorption treatment of the organic-contaminated soil in a short period of time.

It can be understood that laying igniting substances around the heating pipe 2 means laying igniting substances in the area surrounding the heating pipes.

According to the present invention, preferably, the soil pile is in the shape of a trapezoid.

Preferably, the height of the soil pile is 2-4m.

Preferably, the slope of the soil pile is 1:(3-4). It can be understood that the gradient refers to the ratio between the height H of the slope and the horizontal distance L of the slope.

Preferably, the total volume of the soil pile is 500-5000 m ³ .

Preferably, the aspect ratio of the bottom surface of the soil pile is (8-9):1.

Preferably, in the soil pile, the total concentration of organic pollutants is 1000-20000 mg/kg.

Wherein, the specific types of organic pollutants are not particularly limited, for example, they may be petroleum hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and the like.

According to the present invention, preferably, in the direction vertical to the ground, the soil pile is divided into upper, middle and lower parts equally according to height, and the tonic well 14 is located at the upper part of the soil pile.

According to the present invention, preferably, the tonic well 14 is in the form of a tube with a height of 1.25-1.8% of the soil pile, and the tonic well 14 is placed parallel to the long side or wide side of the cross section of the soil pile.

According to the present invention, preferably, the tonic well 14 is placed in the center of the soil pile cross section at the same height in a manner parallel to the broad side of the soil pile cross section.

According to the present invention, preferably, the distance between the upper end of the tonic well 14 and the upper surface of the soil pile is 2.5-3% of the height of the soil pile.

According to the present invention, preferably, a plurality of branch pipes 17 are arranged symmetrically on both sides of the medicine well 14, and a plurality of drug outlet holes are arranged on the branch pipes 17 to disperse the oxidant into the soil; 20-45% of the broadside of the section, and the diameter of the branch pipe 17 is preferably 0.5-1% of the height of the soil pile.

According to the present invention, preferably, the oxidizing agent is selected from at least one of sodium persulfate, ozone and Fenton's reagent.

According to the present invention, preferably, the main body repair module further includes a drug regulator 13 to control the addition of oxidants. It can be used to control the amount and advance rate of the oxidant.

According to the present invention, preferably, the gas injection well 8 is in a tubular shape with a diameter of 3-5% of the height of the soil pile, and the gas injection well 8 is placed parallel to the long side or wide side of the cross section of the soil pile.

According to the present invention, preferably, the gas injection well 8 is placed parallel to the broadside of the soil pile cross section, and the length of the gas pump injection well 8 is 90-95% of the broadside of the soil pile cross section at the same height .

According to the present invention, preferably, there are multiple gas pumping and injecting wells 8, and the multiple gas pumping and injecting wells 8 are preferably arranged on the same horizontal plane and arranged at equal intervals in the horizontal direction. 10-20% of the broad side of the section. The spacing refers to the distance between the cross-sectional centers of two adjacent gas pumping and injection wells.

The gas injection well 8 is located in the area below the tonic well 14 . Preferably, the center of the section of the gas injection well 8 is located at a height of 70-80% of the height of the soil pile.

Under the above conditions, the desorbed organic gas can be more fully resolved.

According to the present invention, preferably, the diameter of the porous medium combustion tube 5 is 4-8% of the height of the soil pile, and the porous medium combustion tube 5 is placed parallel to the long side or wide side of the cross section of the soil pile.

According to the present invention, preferably, the porous medium combustion tube 5 is placed parallel to the broadside of the soil pile cross section, and the length of the porous medium combustion pipe 5 is 90-95% of the broadside of the soil pile cross section at the same height .

According to the present invention, preferably, there are a plurality of porous media combustion tubes 5, and the plurality of porous media combustion tubes 5 are preferably arranged on the same horizontal plane and arranged at equal intervals in the horizontal direction. 10-20% of the long side of the section. The spacing refers to the distance between the cross-sectional centers of two adjacent porous media combustion tubes.

According to the present invention, preferably, in the porous medium combustion tube 5 , the filling height of the first porous medium is 60-80% of the diameter of the porous medium combustion tube 5 . It can be understood that when the tube is filled with material, it must be filled horizontally to ensure that the filling height does not change. Therefore, when the filling height is determined, the total filling amount of the first porous medium is also determined.

The porous media burner tube 5 is in the region below the gas injection well 8 . Preferably, the center of the section of the porous media combustion tube 5 is located at a height of 40-60% of the height of the soil pile.

According to the present invention, preferably, the first porous medium is alumina spheres with a particle diameter of 0.5-1.5 cm and a porosity of 0.35-0.5. The inventors of the present invention also found in their research that by using the above-mentioned first porous medium, the turbulent vortex generated by the gas in the first porous medium further enhances the momentum heat and mass transfer, further improves the flame stability and prolongs the flammability limit .

According to the present invention, preferably, the heating pipe 2 is located at the middle and lower part of the soil pile.

According to the present invention, preferably, the diameter of the heating pipe 2 is 2-3% of the height of the soil pile, and the heating pipe 2 is placed parallel to the long side or wide side of the cross section of the soil pile.

According to the present invention, preferably, the heating pipe 2 is placed parallel to the broadside of the cross-section of the soil pile, and the length of the heating pipe 2 is 90-95% of the broadside of the cross-section of the soil pile at the same height.

According to the present invention, preferably, there are a plurality of heating pipes 2, and the plurality of heating pipes 2 are preferably arranged on the same horizontal plane and arranged at equal intervals in the horizontal direction, and the spacing is preferably the long side of the cross-section of the soil pile at the same height 10-20% of. The pitch refers to the distance between the centers of the cross-sections of adjacent heating tubes.

According to the present invention, preferably, the periphery of the heating pipe 2 is provided with a plurality of metal heat-conducting pipes 3 in a mace shape, so as to lead heat from the heating pipe 2 to the soil pile, and the diameter of the metal heat-conducting pipes 3 is preferably the diameter of the heating pipe (2) 10-20% of; the length of the metal heat pipe 3 is preferably 12-15% of the height of the soil pile.

The heating tube 2 is located in the area below the porous media combustion tube 5 . Preferably, the center of the cross-section of the heating tube 2 is 20-30% of the height of the stack.

Under the above conditions, the soil pile can be heated more uniformly, resulting in a more uniform desorption.

The heating method in the heating tube 2 is not particularly limited, preferably, the heating method in the heating tube 2 is gas or electric heating.

According to the present invention, preferably, the main body repair module further includes a heating controller 1 to control the heating pipe 2 . It can be used to control the temperature in the heating pipe, etc.

According to the present invention, preferably, the thickness of the ignition substance 4 is 5-7.5% of the height of the soil pile. It can be understood that, in the case of multiple heating tubes 2, the thickness of the igniting substance 4 around each heating tube can be within this range, and the specific thickness can also be adjusted according to the distance between multiple heating tubes .

According to the present invention, preferably, the second porous medium is quartz sand, and relative to the total weight of the igniting substance and the quartz sand, the doping amount of the quartz sand is 20-50% by weight. This can change the porosity of the soil, enhance the air permeability of the soil, and further ensure the continuous and stable self-combustion of the organic matter in the soil. The higher the temperature, the better the removal of the organic matter in the soil.

According to the present invention, preferably, the second porous medium is prepared by the following method: under an anaerobic environment with an oxygen content not higher than 0.1% by volume, the average particle size is 0.5-1mm (for example, it can be 0.5 mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1mm and the range formed by any two of the above values and the value within the range) sandy soil at 900-1000°C (for example, it can be 900°C, 910°C, 920°C , 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C and the range formed by any two values above and the value within the range) under heat treatment for 0.3-1h (for example, it can be 0.3 h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h and the range formed by any two of the above values and the value within the range); then the heat-treated material should be kept at an oxygen content of not higher than 0.1 Under the anaerobic environment of volume %, mix with gac, wherein, the quality consumption of gac is the 10-30wt% (for example, can be 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt% of the total mass of mixed material) , 25wt%, 28wt%, 30wt%, and the range formed by any two of the above values and the value within the range).

Preferably, the water content of the sandy soil is lower than 0.01wt%, and the specific surface area is 900-1200cm ² /g (for example, it can be 900cm ² /g, 950cm ² /g, 1000cm ² /g, 1100cm ² /g, 1200cm ² /g and the range formed by any two of the above values and the value within the range), the porosity is 40-55% (for example, it can be 40%, 42%, 45%, 47%, 49%, 50%, 52% %, 55% and the range formed by any two of the above values and values within the range).

Preferably, the specific surface area of activated carbon is 1600-2500cm ² /g (for example, it can be 1600cm ² /g, 1700cm ² /g, 1800cm ² /g, 1900cm ² /g, 2000cm ² /g, 2100cm ² /g, 2200cm ² /g, 2300cm ² /g, 2400cm ² /g, 2500cm ² /g and the range formed by any two of the above values and values within the range), the porosity is 80-90% (for example, it can be 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90% and the range formed by any two of the above values and the values within the range).

The measuring method of the above-mentioned specific surface area and porosity is a gas adsorption method (BET method).

According to the present invention, preferably, in the soil whose volume near the ignition substance 4 is 30-50% of the total volume of the soil pile, the concentration of organic pollutants is not less than 3000 mg/kg. Within the above range, the self-combustion of organic pollutants in the soil can be further ensured. It can be understood that the total concentration of organic pollutants in the soil in areas other than the above-mentioned areas, or in the entire soil pile may not be lower than 3000 mg/kg, as long as the volume near the igniting substance 4 is 30% of the total volume of the soil pile. The concentration of organic pollutants in -50% of the soil is not less than 3000mg/kg, which can further ensure the realization of the spontaneous combustion of organic pollutants in the soil.

Wherein, the specific type of the ignition substance 4 is not particularly limited, for example, it may be biomass, wood chips and the like.

According to the present invention, preferably, the main body repair module further includes a collection pipe 9 , an exhaust gas feedback adjustment optimization device 10 , a water and gas separator 11 and a tail water and tail gas treatment component 12 .

According to the present invention, preferably, a plurality of gas injection wells 8 are all communicated with the collection pipe 9, so that the extracted gas is sent into the collection pipe 9, and the collection pipe 9 communicates with the porous medium combustion pipe 5 through the gas delivery pipe 6, so as to The gas in the collection pipeline is sent into the porous media combustion tube 5 for combustion. Wherein, the gas conveying pipe 6 can also extend to the igniting substance, so that when the gas injection well 8 injects air into the soil pile, the air can smoothly contact with the igniting substance.

According to the present invention, preferably, the tail gas feedback adjustment optimization device 10 is used to record and feed back the state of the extracted gas. For example, the composition, concentration, and quantity of the extracted gas can be recorded and fed back, so that the operator can know the treatment status of the soil, and can regulate the operation of the soil pile accordingly.

According to the present invention, preferably, the tail water and tail gas treatment unit 14 communicates with the collection pipe 9 to treat the organic gas and water extracted but not sent into the porous media combustion tube 5 .

According to the present invention, preferably, the tail water and tail gas treatment unit 14 includes a vacuum pump device, an activated carbon adsorption device and a waste water temporary storage device. The vacuum pump device can extract water, carbon dioxide and other tail gases, and the activated carbon adsorption device can absorb toxic and harmful substances in the tail gas to prevent discharge to the external environment. The waste water temporary storage device can collect and store condensed water.

Wherein, near the junction of the porous medium combustion tube 5 and the gas delivery tube 6, on the porous medium combustion tube 5, SiC foamed ceramics (two or more can be arranged) with a thickness of 20-50cm and a porosity of 20-25ppi block), which can prevent the flame from escaping out of the nozzle when it moves from the downstream of the porous media combustion tube 5 (near the ignition port) to the gas source, thereby ensuring the safe operation of the equipment.

According to the present invention, preferably, the system further includes an external control module, and the external control module includes an electrical control system, a data acquisition system, a data transmission system and a stack operation system. The electrical control system can control the power input and output of the entire thermal stack system. The data acquisition system can monitor the temperature, pressure, moisture and other parameters in the system in real time. The data transmission system can transmit the collected parameters to the stack operation system. The stack operation system can It is used for real-time adjustment of the operating parameters of the heating controller, chemical regulator, and exhaust gas feedback adjustment and optimization device.

According to the present invention, preferably, a rock wool board 15 is laid on the top of the soil pile, and a foamed cement layer 16 is laid above the rock wool board 15 and around the soil pile.

According to the present invention, preferably, the thickness of the rock wool board 15 is 1.25-7.5% of the height of the soil pile.

According to the present invention, preferably, the thickness of the foamed cement layer 16 is 1-5% of the height of the soil pile.

Within the above range, it can effectively prevent energy loss and pollutants from spreading to the external environment, further reduce energy consumption, and fully ensure the temperature of the soil pile.

According to the present invention, preferably, the method includes: opening the heating pipe 2, so that the temperature in the heating pipe 2 is 200-800°C; injecting air into the soil pile through the gas injection well 8, and injecting the air until the igniting substance 4 is completely burned ; use the gas extraction well 8 to extract the desorbed gas, when the tail gas feedback adjustment optimization device 10 shows that in the extracted gas, the organic gas concentration is not less than 500mg/m ^When the extracted gas is sent into the water vapor In the separator, the organic gas and water are separated, and at least part of the separated organic gas is sent to the porous medium combustion tube 5 through the gas delivery pipe 6;

When the exhaust gas feedback adjustment optimization device 10 shows that in the extracted gas, the organic gas concentration is lower than 500mg/ ^m3 , stop sending the extracted desorbed gas into the porous media combustion tube 5; and maintain the stack by the heating controller The body temperature is 100-150°C, and the oxidant is added through the tonic well 14. The total amount of oxidant added is 1-4mmol relative to the mass of 1g of soil heap, and the oxidant is completely added within 1-3h.

According to the present invention, preferably, the air feed rate for injecting air into the soil pile through the gas injection well 8 is 5-30 m ³ /h (relative to the total volume of the soil pile of 1500 m ³ ).

In the early stage, the soil heap has been heated for a period of time, and the extracted desorbed gas is not sent into the porous media combustion tube 5, and in the presence of rock wool boards and foamed cement layers, the soil There is almost no significant difference in temperature across the stack.

Wherein, under the condition that the air pressure in the porous medium combustion tube 5 is not too large, all the organic gases separated in the water-gas separator can be sent into the porous medium combustion tube 5 (can also be based on the combustion in the porous medium combustion tube 5 Situation, adopt air blower etc. to blow into air in porous media combustion tube 5, so that in maintaining the combustion therein). Moreover, it can be understood that when the gas injection well 8 injects air into the soil pile, the air can enter the porous medium combustion tube 5 through the gas delivery pipe 6 and can also contact with the igniting substance.

It can be understood that in the extracted gas (which will contain water vapor, carbon dioxide and organic gases), when the concentration of organic gases is lower than 500mg/ ^m3 , the concentration of organic gases is already low at this time, indicating that it has made the Most of the organic gases that can be desorbed have been desorbed, and at this time, recycling them to the porous media combustion tube 5 is not enough to maintain the combustion therein. Stop at this moment (valve can be provided with on gas conveying pipe 6 and porous medium combustion pipe 5, can control whether conveying by valve opening and closing) the desorbed gas of extraction is sent in porous medium combustion pipe 5, and by maintaining The heating of the heating pipe 2 and the addition of the oxidizing agent, the coupling of the oxidizing agent and the heating function, can fully remove the residual organic matter from the soil. Especially in the case of adding the total amount, advancing speed, and adding time of the above-mentioned limited oxidant, the residual organic matter can be more fully removed from the soil.

Wherein, temperature sensors may be installed at different positions of the stack to know the temperature conditions at different positions. In addition, a temperature sensor can also be arranged near the igniting substance. When the igniting substance burns, the temperature is relatively high. When the temperature there drops significantly, it can be determined that the igniting substance has completely burned.

In a second aspect, the invention provides a system as described in the first aspect.

The present invention will be described in detail below by way of examples.

In the following examples, the concentration of organic pollutants (organic pollutants of concern is petroleum hydrocarbons) in the soil is detected according to the national standard method, and the calculation method of organic pollutant degradation rate is: 100% * (initial organic pollutant concentration-treatment ends concentration of organic pollutants at the time)/initial concentration of organic pollutants.

The following embodiments are implemented in the system shown in Figures 1-2.

As shown in Figure 1-2, 1 is the heating controller, 2 is the heating pipe, 3 is the metal heat pipe, 4 is the ignition material, 5 is the porous medium combustion pipe, 6 is the gas delivery pipe, 7 is the valve, and 8 is the gas pump. Injection well, 9 is the collection pipeline, 10 is the tail gas feedback adjustment optimization device, 11 is the water and gas separator, 12 is the tail water tail gas treatment part, 13 is the chemical control instrument, 14 is the tonic well, 15 is the rock wool board, 16 is Foamed cement layer, 17 is the medicine well branch pipe.

As shown in Figure 1-2, the soil pile is in the shape of a trapezoid with a height of 3m and a slope of 1:4. The total volume of the soil pile is 1500m ³ , the length of the bottom is 80m, the width is 10m, and the aspect ratio is 8: 1. In the soil pile, the total concentration of organic pollutants (petroleum hydrocarbons) was 8500 mg/kg. On the top of the soil pile, a rock wool board 15 is laid, and a foam cement layer 16 is laid on the top of the rock wool board 15 and around the soil pile; the thickness of the rock wool board 15 is 5% of the height of the soil pile; the foam cement Layer 16 has a thickness of 2% of the height of the soil pile.

In the direction vertical to the ground, the soil pile is equally divided into upper, middle and lower parts according to height. The tonic well 14 is located at the top of the soil heap, the upper end is 8cm away from the upper surface of the soil heap, and is placed in the center of the soil heap cross section at the same height in a manner parallel to the broadside of the soil heap cross section, and the tonic well 14 is a tubular shape with a diameter of 5cm . A plurality of branch pipes are symmetrically arranged on both sides of the tonic well 14, and a plurality of drug outlet holes are arranged on the branch pipes to disperse the oxidant in the soil; the length of the branch pipes is 3 cm, and the diameter of the branch pipes is 2 cm.

The gas pumping and injecting wells 8 are tubular with a diameter of 10 cm; there are 8 gas pumping and injecting wells 8, and the 8 gas pumping and injecting wells 8 are arranged on the same horizontal plane and arranged at equal intervals in the horizontal direction with a spacing of 70 cm; 8 Two gas injection wells 8 are placed parallel to the broadside of the soil heap cross section, and the length of each gas injection well 8 is 90% of the broadside of the soil heap cross section at the same height; Located below the tonic well 14, the center of the section of the gas injection well 8 is at a height of 70% of the height of the soil pile.

The diameter of the porous media combustion tube 5 is 20 cm, and there are 9 porous media combustion tubes 5, and the 9 porous media combustion tubes 5 are arranged on the same horizontal plane with equal intervals in the horizontal direction, and the spacing is 5 m; The medium combustion tubes 5 are placed parallel to the broadside of the soil pile cross-section, and the length of each porous medium combustion tube 5 is 90% of the broadside of the soil pile cross-section at the same height. The porous medium combustion tube 5 is located below the gas pumping well 8, and the center of the section of the porous medium combustion tube 5 is at a height of 40% of the height of the soil pile. Each porous media combustion tube 5 is filled with alumina pellets with a particle size of 1 cm and a porosity of 0.45, and the filling height of the alumina pellets is 60% of the diameter of the porous media combustion tube 5 .

The diameter of the heating pipe 2 is 6cm, and there are 9 heating pipes 2, and the 9 heating pipes 2 are arranged on the same horizontal plane, and are arranged at equal intervals in the horizontal direction, and the spacing is 7cm; the 9 heating pipes 2 are parallel to the soil. The broadside of the pile cross-section is placed, and the length of the heating pipe 2 is 90% of the broadside of the soil pile cross-section at the same height; 20% of the stack height. The periphery of each heating pipe 2 is provided with a plurality of metal heat-conducting pipes 3 in a mace shape, so as to lead heat from the heating pipe 2 to the soil pile. The diameter of the metal heat-conducting pipe 3 is 1 cm; the length of the metal heat-conducting pipe 3 is 36 cm; The heating method in the tube 2 is electric heating. The heating tube 2 is connected with the heating controller 1 to control the heating tube.

An igniter 4 is laid around the heating pipe 2, the thickness of the ignite 4 is 15 cm, and the ignite is doped with quartz sand. In the soil whose volume near the igniting substance 4 is 30% of the total volume of the soil pile, the concentration of organic pollutants is 8500mg/kg.

The main body repair module also includes a collection pipeline 9, an exhaust gas feedback adjustment optimization device 10, a water and gas separator 11, and tail water and tail gas treatment components 12;

The 8 gas pumping and injection wells 8 are all communicated with the collection pipeline 9 to send the extracted gas into the collection pipeline 9, and the collection pipeline 9 communicates with the gas delivery pipe 6 and the porous medium combustion pipe 5 to send the gas in the collection pipeline to into the porous medium combustion tube 5 for combustion; the gas delivery pipe 6 extends downward to the igniter 4, so that when the gas injection well 8 injects air into the soil pile, the air can smoothly contact with the igniter.

The tail gas feedback adjustment optimization device 10 is used to record and feed back the state of the extracted gas;

Tail water and tail gas treatment unit 14 communicates with collection pipeline 9 to treat the organic gas and water extracted but not sent into porous media combustion tube 5;

The tail water and tail gas treatment unit 14 includes a vacuum pump device, an activated carbon adsorption device and a waste water temporary storage device;

At the junction of the porous media combustion pipe 5 and the gas delivery pipe 6, two pieces of SiC foam ceramics with a thickness of 20 cm and a porosity of 20 ppi are arranged on the porous media combustion pipe 5;

The system also includes an external control module, which includes an electrical control system, a data acquisition system, a data transmission system and a stack operation system. The electrical control system is used to control the power input and output of the entire thermal stack system. The data acquisition system monitors the temperature, pressure, moisture and other parameters in the system in real time. The data transmission system is used to transmit the collected parameters to the stack operation system. It is used for real-time adjustment of the operating parameters of the heating controller, chemical regulator, and exhaust gas feedback adjustment and optimization device.

Example 1

The system shown in Fig. 1-2 is adopted, wherein, relative to the total weight of the ignition substance and the quartz sand, the doping amount of the quartz sand is 35% by weight.

Turn on the heating tube 2 so that the temperature in the heating tube 2 is 400°C; inject air into the soil pile through the gas injection well 8 at a speed of 1 m ³ /h, and inject the air until the igniter 4 (wood chips) is completely combusted.

Then, adopt the gas extraction and injection well 8 to extract the desorbed gas, when the tail gas feedback adjustment optimization device 10 shows that in the extracted gas, the organic gas concentration is not lower than 500mg/ ^m3 , the extracted gas is sent into the water In the gas separator, the organic gas and water are separated, and all the separated organic gas is sent to the porous medium combustion tube 5 through the gas delivery pipe 6 .

When the exhaust gas feedback adjustment optimization device 10 shows that in the extracted gas, the organic gas concentration is lower than 500mg/ ^m3 , stop sending the extracted desorbed gas into the porous media combustion tube 5; and maintain the stack by the heating controller The body temperature is about 120°C, and the oxidizing agent (sodium persulfate) is added through the tonic well 14. The total amount of oxidizing agent added is 1 mmol relative to the mass of 1 g of soil heap, and the oxidizing agent is completely added within 2 hours.

The concentration of organic pollutants in the soil was monitored every day, and it was found that when heating for 30 days (calculated from the time when the heating tube reached 400°C), the concentration of organic pollutants in the soil dropped to 442mg/kg, and the degradation rate of organic pollutants was 94.8%.

Example 2

Carry out in the same manner as in Example 1, except that, relative to the total weight of the igniting substance and the quartz sand, the doping amount of the quartz sand is 20% by weight.

The concentration of organic pollutants in the soil was monitored every day, and it was found that when heated for 30 days, the concentration of organic pollutants in the soil dropped to 620mg/kg, and the degradation rate of organic pollutants was 92.7%.

Example 3

Carry out in the same manner as in Example 1, except that, relative to the total weight of the igniting substance and the quartz sand, the doping amount of the quartz sand is 5% by weight. The concentration of organic pollutants in the soil was monitored every day, and it was found that when heated for 30 days, the concentration of organic pollutants in the soil dropped to 986mg/kg, and the degradation rate of organic pollutants was 88.4%.

Example 4

The method is carried out in the same manner as in Example 1, except that each porous media combustion tube 5 is filled with alumina pellets with a particle diameter of 0.3 cm and a porosity of 0.15. The concentration of organic pollutants in the soil was monitored every day, and it was found that when heated for 30 days, the concentration of organic pollutants in the soil dropped to 1080mg/kg, and the degradation rate of organic pollutants was 87.3%.

Example 5

Carry out according to the mode among the embodiment 1, difference is, the quartz sand doped in the igniting substance is replaced by the product prepared according to the following method:

Under an anaerobic environment with an oxygen content not higher than 0.1 volume percent, the sandy soil with an average particle size of 0.7 mm (wherein the water content is lower than 0.01 wt %, the specific surface area is 1000 cm ² /g, and the porosity is 45%) at 950 Heat treatment at ℃ for 0.5h; then mix the heat-treated material with activated carbon (specific surface area ^2000cm2 /g, porosity 85%) in an anaerobic environment with an oxygen content not higher than 0.1% by volume, wherein the activated carbon The mass dosage is 20wt% of the total mass of the mixed material.

The concentration of organic pollutants in the soil was monitored every day, and it was found that when heated for 30 days, the concentration of organic pollutants in the soil dropped to 420mg/kg, and the degradation rate of organic pollutants was 95.1%.

Comparative example 1

Proceed in the same manner as in Example 1, except that the igniter is not doped with quartz sand.

When heated for 30 days, the concentration of organic pollutants in the soil dropped to 1542mg/kg, and the degradation rate of organic pollutants was 81.9%.

Comparative example 2

Proceed in the same manner as in Example 1, except that the organic gas separated by the water-gas separator 11 is not sent into the porous media combustion tube 5, that is, the porous media combustion tube 5 is not opened.

The concentration of organic pollutants in the soil was monitored every day, and it was found that when heated for 30 days, the concentration of organic pollutants in the soil dropped to 1635mg/kg, and the degradation rate of organic pollutants was 80.8%.

Comparative example 3

Proceed in the same manner as in Example 1, except that no igniting substance 4 is laid around the heating pipe 2, and air does not need to be injected into the igniting substance 4 until the igniting substance 4 is completely burned.

The concentration of organic pollutants in the soil was monitored every day, and it was found that when heated for 30 days, the concentration of organic pollutants in the soil dropped to 2380mg/kg, and the degradation rate of organic pollutants was 72%.

Comparative example 4

Proceed in the same manner as in Example 1, except that no oxidizing agent is added through the supplementary well 14 .

The concentration of organic pollutants in the soil was monitored every day, and it was found that when heated for 30 days, the concentration of organic pollutants in the soil dropped to 2150mg/kg, and the degradation rate of organic pollutants was 74.7%.

Comparative example 5

Proceed according to the system in Example 1, the difference is that the heating tube 2 is not opened from the beginning to the end, and the porous medium combustion tube is not opened, and the oxidant is only added according to the addition method of the oxidant in Example 1, through the gas pumping well 8 Extract gas. At 30 days, the concentration of organic pollutants in the soil dropped to 5320mg/kg, and the degradation rate of organic pollutants was 37.4%.

The preferred embodiments of the present invention have been described in detail above, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims (10)

1. A porous medium combustion type organic matter contaminated soil heap thermal remediation method, which is characterized in that the method is implemented in a system comprising a main body remediation module;

the main body repairing module comprises a soil pile to be treated, wherein a chemical supplementing well (14), a gas pumping and injecting well (8), a porous medium combustion tube (5) and a heating tube (2) are sequentially arranged in the soil pile from top to bottom;

the chemical supplementing well (14) is used for adding an oxidant into the soil pile; the porous medium combustion pipe (5) is filled with a first porous medium, and the porous medium combustion pipe (5) is used for burning and releasing heat to the soil pile; the gas pumping and injecting well (8) is used for injecting air into the soil pile or extracting the desorbed gas from the soil pile; the heating pipe (2) is used for heating the soil pile; the gas pumping and injecting well (8) is communicated with the porous medium combustion pipe (5) so that the gas pumped by the gas pumping and injecting well (8) can enter the porous medium combustion pipe (5) for combustion; a pilot substance (4) is paved around the heating pipe (2), and a second porous medium is doped in the pilot substance (4);

The method comprises the following steps: starting a heating pipe (2) to heat the soil pile, extracting desorbed gas by adopting a gas extraction and injection well (8), sending at least part of the desorbed gas into a porous medium combustion pipe (5) for combustion, and injecting air into the soil pile by adopting the gas extraction and injection well (8) to enable the ignition material (4) to burn in the presence of oxygen; and oxidant is added through the drug supplementing well (14).

2. The method of claim 1, wherein the soil pile is trapezoidal in shape;

and/or the height of the soil pile is 2-4m.

And/or the gradient of the soil pile is 1 (3-4);

and/or the total volume of the soil pile is 500-5000m ³ ；

And/or the aspect ratio of the bottom surface of the soil pile is (8-9): 1, a step of;

and/or the total concentration of organic pollutants in the soil pile is 1000-20000mg/kg.

3. The method of claim 2, wherein the soil pile is divided into three parts, an upper part, a middle part and a lower part by height in the vertical ground direction, and the chemical supplementing well (14) is positioned at the upper part of the soil pile;

preferably, the medicine supplementing well (14) is in a tubular shape with the diameter of 1.25-1.8% of the height of the soil pile, and the medicine supplementing well (14) is placed in a mode of being parallel to the long side or the wide side of the cross section of the soil pile;

preferably, the patch well (14) is placed in the centre of the cross section of the pile at the same level in a manner parallel to the broadsides of the cross section of the pile;

Preferably, the distance between the upper end of the medicine supplementing well (14) and the upper surface of the soil pile is 2.5-3% of the height of the soil pile;

preferably, a plurality of branch pipes (17) are symmetrically arranged at two sides of the medicine supplementing well (14), and a plurality of medicine outlet holes are formed in the branch pipes (17) so as to disperse the oxidant into the soil; the length of the branch pipe (17) is preferably 20-45% of the wide side of the cross section of the soil pile at the same height, and the diameter of the branch pipe (17) is preferably 0.5-1% of the height of the soil pile;

and/or the oxidant is selected from at least one of sodium persulfate, ozone and Fenton reagent;

and/or the main body repair module further comprises a medicament regulating and controlling instrument (13) for controlling the addition of the oxidant.

4. A method according to claim 3, wherein the gas injection well (8) is tubular with a diameter of 3-5% of the height of the pile, the gas injection well (8) being placed parallel to the long or wide sides of the pile cross section;

preferably, the gas pumping and injecting well (8) is placed in a mode of being parallel to the wide side of the cross section of the soil pile, and the length of the gas pumping and injecting well (8) is 90-95% of the wide side of the cross section of the soil pile at the same height;

preferably, the plurality of gas pumping and injecting wells (8) are arranged in a mode of being uniformly spaced in the horizontal direction, wherein the spacing is preferably 10-20% of the broadsides of the cross section of the soil pile at the same height;

Preferably, the center of the cross section of the gas pumping and injecting well (8) is positioned at the height of 70-80% of the soil pile height;

and/or the diameter of the porous medium combustion tube (5) is 4-8% of the height of the soil pile, and the porous medium combustion tube (5) is placed in a manner of being parallel to the long side or the wide side of the cross section of the soil pile;

preferably, the porous medium combustion tube (5) is placed in a manner of being parallel to the broad side of the cross section of the soil pile, and the length of the porous medium combustion tube (5) is 90-95% of the broad side of the cross section of the soil pile at the same height;

preferably, the porous medium combustion pipes (5) are a plurality of, the porous medium combustion pipes (5) are preferably arranged on the same horizontal plane in a mode of equal spacing in the horizontal direction, and the spacing is preferably 10-20% of the long side of the cross section of the soil pile at the same height;

and/or, in the porous medium combustion tube (5), the filling height of the first porous medium is 60-80% of the diameter of the porous medium combustion tube (5);

preferably, the center of the cross section of the porous medium combustion tube (5) is positioned at the height of 40-60% of the soil pile height;

and/or the first porous medium is alumina sphere with particle diameter of 0.5-1.5cm and porosity of 0.35-0.5.

5. A method according to claim 3, wherein the heating pipe (2) is located in the lower middle part of the soil pile;

Preferably, the diameter of the heating pipe (2) is 2-3% of the height of the soil pile, and the heating pipe (2) is placed in a manner of being parallel to the long side or the wide side of the cross section of the soil pile;

preferably, the heating pipe (2) is placed in a manner parallel to the broadside of the cross section of the soil pile, and the length of the heating pipe (2) is 90-95% of the broadside of the cross section of the soil pile at the same height;

preferably, the heating pipes (2) are a plurality of, and the plurality of heating pipes (2) are preferably arranged on the same horizontal plane in a mode of equidistant horizontal direction, wherein the distance is preferably 10-20% of the long side of the cross section of the soil pile at the same height;

preferably, a plurality of metal heat-conducting pipes (3) are arranged on the periphery of the heating pipe (2) in a wolf tooth shape so as to lead heat from the heating pipe (2) to the soil pile, and the diameter of each metal heat-conducting pipe (3) is preferably 10-20% of the diameter of the heating pipe (2); the length of the metal heat-conducting pipe (3) is preferably 12-15% of the height of the soil pile;

preferably, the center of the section of the heating pipe (2) is positioned at the height of 20-30% of the soil pile height;

preferably, the heating mode in the heating pipe (2) is gas or electric heating;

preferably, the body repair module further comprises a heating controller (1) to control the heating pipe (2).

6. A method according to claim 3, wherein the thickness of the ignition material (4) is 5-7.5% of the height of the soil pile;

And/or the second porous medium is quartz sand, and the doping amount of the quartz sand is 20-50 wt% relative to the total weight of the ignition substance and the quartz sand;

and/or, the second porous medium is prepared by the following method: under anaerobic environment with oxygen content not higher than 0.1 volume%, heat treating sand with average particle size of 0.5-1mm at 900-1000deg.C for 0.3-1 hr; then mixing the heat-treated material with activated carbon in an anaerobic environment with the oxygen content not higher than 0.1 volume percent, wherein the mass dosage of the activated carbon is 10-30wt% of the total mass of the mixed material;

and/or, the concentration of organic pollutants in the soil, the volume of which is 30-50% of the total volume of the soil pile, near the ignition substance (4) is not less than 3000mg/kg.

7. The method of claim 4, wherein the body repair module further comprises a collecting pipe (9), an exhaust gas feedback conditioning optimizing device (10), a moisture separator (11) and a tail water exhaust gas treatment component (12);

the gas pumping and injecting wells (8) are communicated with the collecting pipeline (9) so as to send the pumped gas into the collecting pipeline (9), and the collecting pipeline (9) is communicated with the porous medium combustion pipe (5) through the gas conveying pipe (6) so as to send the gas in the collecting pipeline into the porous medium combustion pipe (5) for combustion;

The tail gas feedback adjustment optimizing device (10) is used for recording and feeding back the extracted gas state;

the tail water tail gas treatment component (14) is communicated with the collecting pipeline (9) so as to treat the organic gas and water which are extracted but not fed into the porous medium combustion pipe (5);

the tail water and tail gas treatment component (14) comprises a vacuum pump device, an activated carbon adsorption device and a wastewater temporary storage device;

preferably, the system further comprises an external control module, wherein the external control module comprises an electrical control system, a data acquisition system, a data transmission system and a stack operation system.

8. The method according to claim 7, wherein on top of the pile there is laid rock wool boards (15), above which rock wool boards (15) and around the pile there is laid a layer of foamed cement (16);

preferably, the thickness of the rock wool board (15) is 1.25-7.5% of the soil pile height;

preferably, the foamed cement layer (16) has a thickness of 1-5% of the soil pile height.

9. According to claimThe method of 8, wherein the method comprises: starting the heating pipe (2) to enable the temperature in the heating pipe (2) to be 200-800 ℃; injecting air into the soil pile through the gas pumping and injecting well 8 until the ignition substances (4) are completely combusted; the desorbed gas is extracted by a gas extraction and injection well (8), and when the tail gas feedback adjustment optimizing device (10) shows that the concentration of the organic gas in the extracted gas is not lower than 500mg/m ³ When the gas is pumped, the pumped gas is sent into a water-gas separator to separate organic gas and water, and at least part of the separated organic gas is sent into a porous medium combustion pipe (5) through a gas conveying pipe (6);

when the tail gas feedback regulation optimizing device (10) shows that the concentration of the organic gas in the extracted gas is lower than 500mg/m ³ When the desorption gas is not fed into the porous medium combustion tube (5); and maintaining the temperature of the pile body at 100-150 ℃ through a heating controller, adding an oxidant through a chemical supplementing well (14), wherein the total adding amount of the oxidant is 1-4mmol relative to the mass of 1g of the soil pile, and the oxidant is completely added within 1-3 h.

10. The system of any one of claims 1-9.

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