阅读说明：本技术 用于有机污染土壤热脱附的回转热脱附窑、装置及工艺 (rotary thermal desorption kiln, device and process for thermal desorption of organic contaminated soil ) 是由 毛永强 邢汉君 冉启洋 邹先军 聂芳 于 2019-08-30 设计创作，主要内容包括：本发明“用于有机污染土壤热脱附的回转热脱附窑、装置及工艺”,属于有机污染土壤处理技术领域。所述回转热脱附窑包括用于容纳有机污染土壤并对其热脱附的热脱附腔和用于燃烧热脱附产生的有机气体的燃烧室,二者均为热脱附回转热脱附窑中的独立分隔的腔室；所述热脱附腔与燃烧室之间有气体通道连通,气体通道贯穿窑头罩和窑尾罩。本发明的回转热脱附窑热能得到了充分的利用,能耗少,结构紧凑,操作控制简单,减少了投资。(the invention discloses a rotary thermal desorption kiln, a device and a process for thermal desorption of organic contaminated soil, and belongs to the technical field of organic contaminated soil treatment. The rotary thermal desorption kiln comprises a thermal desorption cavity for containing and thermally desorbing the organic contaminated soil and a combustion chamber for combusting organic gas generated by thermal desorption, wherein the thermal desorption cavity and the combustion chamber are both independent and separated chambers in the thermal desorption rotary thermal desorption kiln; and a gas channel is communicated between the heat desorption cavity and the combustion chamber and penetrates through the kiln head cover and the kiln tail cover. The rotary thermal desorption kiln has the advantages of full utilization of heat energy, low energy consumption, compact structure, simple operation and control and reduced investment.)

1. A rotary thermal desorption kiln for thermal desorption of organic contaminated soil comprises a thermal desorption cavity for containing and thermally desorbing the organic contaminated soil and a combustion chamber for combusting organic gas generated by thermal desorption, wherein the thermal desorption cavity and the combustion chamber are independently separated chambers in the thermal desorption rotary thermal desorption kiln; and a gas channel is communicated between the heat desorption cavity and the combustion chamber and penetrates through the kiln head cover and the kiln tail cover.

2. The rotary thermal desorption kiln according to claim 1, wherein the combustion chamber is a hollow cylindrical cavity structure arranged at the center of the rotary thermal desorption kiln; the space between the outer wall of the combustion chamber and the inner wall of the rotary thermal desorption kiln is the thermal desorption cavity; the kiln tail end of the thermal desorption cavity close to the rotary thermal desorption kiln is provided with a wedge-shaped annular air port, the kiln tail end of the combustion chamber close to the rotary thermal desorption kiln is opened in the rotary thermal desorption kiln, and the wedge-shaped annular air port and the kiln tail end of the combustion chamber close to the rotary thermal desorption kiln form the gas channel.

3. A rotary thermal desorption kiln according to claim 1 or 2, wherein the rotary thermal desorption kiln is provided with a negative pressure forming device;

Preferably, the negative pressure forming device comprises an annular air port of a kiln tail cover of the rotary thermal desorption kiln, a butterfly valve of an exhaust pipe on the kiln tail cover, a wedge-shaped annular air port of a kiln head and a combustor;

More preferably, a kiln tail cover is arranged at the kiln tail of the rotary thermal desorption kiln, a tail gas exhaust pipe is arranged on the kiln tail cover, and a butterfly valve is arranged on the tail gas exhaust pipe;

A kiln head cover is arranged at the kiln head of the rotary thermal desorption kiln, and a burner is arranged at the center of the kiln head cover;

Preferably, the center of the kiln head cover is inwards sunken, and temperature and pressure measuring devices are arranged above the kiln head cover and the kiln tail cover.

the burner can only be arranged on the kiln head cover, the flame is sprayed towards the interior of the kiln, and negative pressure is formed at the wedge-shaped annular air port by utilizing the spraying speed of the flame; the inward recess of the center of the kiln head cover specifically means that the outer wall of the inner wall of the kiln head cover is inward recess, so that the shape of the kiln head air port is wedge-shaped when viewed from the section, namely a wedge-shaped annular air port is formed, the air port in the shape can generate negative pressure in the kiln head cover, and only when the negative pressure is formed, hot air in the combustion chamber can enter the heat desorption cavity.

4. A rotary thermal desorption kiln according to claims 1 to 3, wherein the shell of the combustion chamber of the rotary thermal desorption kiln is formed by pouring refractory castable into the combustion chamber cylinder; the thermal desorption cavity of the rotary thermal desorption kiln comprises a rotary cylinder of the rotary thermal desorption kiln, a combustion chamber cylinder and a supporting piece for supporting the combustion chamber cylinder;

Preferably, the inclination angle of the rotary drum is 1-8 degrees, the feeding end is high, and the discharging end is low; the rotating speed of the rotary drum is 1-8 rpm; the feeding end in the rotary cylinder is provided with a material guide arc-shaped plate.

5. The rotary thermal desorption kiln of claim 4 wherein a support member is axially disposed between the housing of the combustion chamber and the rotary drum housing;

preferably, the supporting piece is 8 heat-resistant steel plates uniformly distributed along the circumferential direction of the rotary drum; 8 independent heat desorption cavities are formed among the 8 heat-resistant steel plates.

6. Device for ex situ thermal desorption of organically contaminated soil, characterized in that it comprises a rotary thermal desorption kiln according to any of claims 1 to 5.

7. The apparatus of claim 6, further comprising a feed system and an effluent cooling system; the feeding system, the rotary thermal desorption kiln and the discharging cooling system are sequentially connected;

preferably, the feeding system comprises a receiving hopper A, a feeding belt conveyor, a receiving hopper B and a feeding screw conveyor;

The discharging cooling system comprises a discharging cooler and a discharging belt conveyor;

Preferably, the outlet of the receiving hopper A is connected with the feeding end of a feeding belt conveyor; an inlet of the receiving hopper B is connected with a discharge end of the feeding belt conveyor, and an outlet of the receiving hopper B is connected with a feed end of the feeding spiral conveyor; the feeding screw conveyer is arranged below the end surface of a kiln tail cover of the rotary thermal desorption kiln, and the discharge end of the conveyer belt extends into a material guide arc plate of a rotary cylinder of the rotary thermal desorption kiln;

a feed port of the discharge cooler is connected with a discharge port of a kiln head cover of the rotary thermal desorption kiln, and the discharge port is connected with a discharge belt conveyor;

the discharging cooler is a water tank type water-cooling three-level screw conveyor, and water is introduced into a screw shaft of the discharging cooler for cooling.

8. the apparatus of claim 6 or 7, further comprising an off-gas treatment system; the tail gas treatment system comprises a cyclone separator, a bag-type dust collector, a spray cooling tower, an ash discharging belt conveyor and a tail gas fan;

The outlet of the cyclone separator is connected with the feed inlet of the discharge cooler; the outlet of the bag-type dust collector is connected with the ash discharging belt conveyor; the outlet end of the spray cooling tower is connected with a sewage treatment system;

preferably, star-shaped blanking valves are arranged at the outlet ends of the cyclone separator, the bag-type dust collector and the spray cooling tower; the ash discharging belt conveyor is provided with a water nozzle.

9. A process for ex situ thermal desorption of organically contaminated soil, comprising: use of a rotary thermal desorption kiln according to any one of claims 1 to 5 and/or a device according to any one of claims 6 to 8 for thermal desorption of organically contaminated soil.

10. The process of claim 9, further comprising: carrying out a pretreatment step of the organic contaminated soil before thermal desorption and a tail gas treatment step after thermal desorption;

preferably, the off-gas treatment step is carried out by an off-gas treatment system using the apparatus according to any one of claims 6 to 8;

Preferably, the step of pretreating the organic contaminated soil comprises naturally drying the organic contaminated soil, then crushing, screening and grading;

Preferably, the crushed particles of the organic contaminated soil are classified according to the particle sizes of more than 50mm, 50-30 mm, 30-10 mm and less than 10mm, and the soil with different particle sizes is separately treated during thermal desorption.

Technical Field

The invention belongs to the field of soil remediation, and particularly relates to a rotary thermal desorption kiln, a device and a process for thermal desorption of organic contaminated soil.

Background

The existing heterotopic thermal desorption technology for organic contaminated soil mainly adopts a drum-type thermal desorption technology, and the technology is introduced from foreign countries. The domestic technology mainly adopts a rotary kiln to carry out thermal desorption, and then adopts different modes to treat gas generated by thermal desorption, such as a biological method, a condensation method, an adsorption method, a secondary combustion method and the like, for example:

the invention patent application 201710713790.1 discloses an external heating type thermal desorption rotary kiln, which comprises a furnace tube and a hearth, wherein the furnace tube and the hearth are mutually hermetically isolated, one end of the furnace tube is a feeding end, the other end of the furnace tube is a discharging end, and the hearth is coated outside the space between the two ends of the furnace tube and provides heat for the furnace tube.

The invention patent application 201810163495.8 provides a soil thermal desorption remediation device comprising: the screw feeder comprises a feeder cylinder, and the feeder cylinder is provided with a feeding hole and a discharging hole; the electric heating furnace comprises a sealed furnace body and an electric heating device positioned in the furnace body; the roller penetrates through the furnace body and has freedom degree of axial rotation, a spiral material guide plate is arranged on the inner wall of the roller, and the discharge end of the feeder cylinder is connected with the feed end of the roller; and the driving device is connected with the roller and drives the roller to rotate around the shaft.

It can be seen that the existing thermal desorption equipment reported at present is that the organic gas generated by the thermal desorption and desorption of the organic polluted soil is respectively treated by two processes, and the process is long and the energy consumption is high.

disclosure of Invention

Aiming at the defects of the prior art, the invention provides a novel organic contaminated soil ex-situ thermal desorption device and a novel organic contaminated soil ex-situ thermal desorption process, aiming at solving two working procedures of integrated treatment of organic gas generated by thermal desorption and organic contaminated soil thermal desorption, shortening the flow, improving the efficiency and reducing the energy consumption.

The invention is realized by the following technical scheme:

a rotary thermal desorption kiln for thermal desorption of organic contaminated soil comprises a thermal desorption cavity for containing and thermally desorbing the organic contaminated soil and a combustion chamber for combusting organic gas generated by thermal desorption, wherein the thermal desorption cavity and the combustion chamber are independently separated chambers in the thermal desorption rotary thermal desorption kiln; and a gas channel is communicated between the heat desorption cavity and the combustion chamber and penetrates through the kiln head cover and the kiln tail cover.

The combustion chamber is of a hollow cylindrical cavity structure arranged at the center of the rotary thermal desorption kiln; the space between the outer wall of the combustion chamber and the inner wall of the rotary thermal desorption kiln is the thermal desorption cavity; the kiln tail end of the thermal desorption cavity close to the rotary thermal desorption kiln is provided with a wedge-shaped annular air port, the kiln tail end of the combustion chamber close to the rotary thermal desorption kiln is opened in the rotary thermal desorption kiln, and the wedge-shaped annular air port and the kiln tail end of the combustion chamber close to the rotary thermal desorption kiln form the gas channel.

The rotary thermal desorption kiln is provided with a negative pressure forming device;

Preferably, the negative pressure forming device comprises an annular air port of a kiln tail cover of the rotary thermal desorption kiln, a butterfly valve of an exhaust pipe on the kiln tail cover, a wedge-shaped annular air port of a kiln head and a combustor;

More preferably, a kiln tail cover is arranged at the kiln tail of the rotary thermal desorption kiln, a tail gas exhaust pipe is arranged on the kiln tail cover, and a butterfly valve is arranged on the tail gas exhaust pipe;

A kiln head cover is arranged at the kiln head of the rotary thermal desorption kiln, and a burner is arranged at the center of the kiln head cover;

preferably, the center of the kiln head cover is inwards sunken, and temperature and pressure measuring devices are arranged above the kiln head cover and the kiln tail cover.

The burner can only be arranged on the kiln head cover, the flame is sprayed towards the interior of the kiln, and negative pressure is formed at the wedge-shaped annular air port by utilizing the spraying speed of the flame; the inward recess of the center of the kiln head cover specifically means that the outer wall of the inner wall of the kiln head cover is inward recess, so that the shape of the kiln head air port is wedge-shaped when viewed from the section, namely a wedge-shaped annular air port is formed, the air port in the shape can generate negative pressure in the kiln head cover, and only when the negative pressure is formed, hot air in the combustion chamber can enter the heat desorption cavity.

The shell of the combustion chamber of the rotary thermal desorption kiln is formed by pouring refractory castable into a cylinder body of the combustion chamber; the thermal desorption cavity of the rotary thermal desorption kiln comprises a rotary cylinder of the rotary thermal desorption kiln, a combustion chamber cylinder and a supporting piece for supporting the combustion chamber cylinder;

Preferably, the inclination angle of the rotary drum is 1-8 degrees, the feeding end is high, and the discharging end is low; the rotating speed of the rotary drum is 1-8 rpm; the feeding end in the rotary cylinder is provided with a material guide arc-shaped plate.

a support piece is axially arranged between the shell of the combustion chamber and the shell of the rotary cylinder;

Preferably, the supporting piece is 8 heat-resistant steel plates uniformly distributed along the circumferential direction of the rotary drum; 8 independent heat desorption cavities are formed among the 8 heat-resistant steel plates.

a device for organic contaminated soil dystopy thermal desorption, characterized in that includes gyration thermal desorption kiln.

The device also comprises a feeding system and a discharge cooling system; the feeding system, the rotary thermal desorption kiln and the discharging cooling system are sequentially connected;

preferably, the feeding system comprises a receiving hopper A, a feeding belt conveyor, a receiving hopper B and a feeding screw conveyor;

The discharging cooling system comprises a discharging cooler and a discharging belt conveyor;

preferably, the outlet of the receiving hopper A is connected with the feeding end of a feeding belt conveyor; an inlet of the receiving hopper B is connected with a discharge end of the feeding belt conveyor, and an outlet of the receiving hopper B is connected with a feed end of the feeding spiral conveyor; the feeding screw conveyer is arranged below the end surface of a kiln tail cover of the rotary thermal desorption kiln, and the discharge end of the conveyer belt extends into a material guide arc plate of a rotary cylinder of the rotary thermal desorption kiln;

a feed port of the discharge cooler is connected with a discharge port of a kiln head cover of the rotary thermal desorption kiln, and the discharge port is connected with a discharge belt conveyor;

the discharging cooler is a water tank type water-cooling three-level screw conveyor, and water is introduced into a screw shaft of the discharging cooler for cooling.

The device also comprises a tail gas treatment system; the tail gas treatment system comprises a cyclone separator, a bag-type dust collector, a spray cooling tower, an ash discharging belt conveyor and a tail gas fan;

the outlet of the cyclone separator is connected with the feed inlet of the discharge cooler; the outlet of the bag-type dust collector is connected with the ash discharging belt conveyor; the outlet end of the spray cooling tower is connected with a sewage treatment system;

Preferably, star-shaped blanking valves are arranged at the outlet ends of the cyclone separator, the bag-type dust collector and the spray cooling tower; the ash discharging belt conveyor is provided with a water nozzle.

A process for ex situ thermal desorption of organically contaminated soil, comprising: the rotary thermal desorption kiln is utilized, and/or the device is used for carrying out thermal desorption on the organic contaminated soil.

The process further comprises: carrying out a pretreatment step of the organic contaminated soil before thermal desorption and a tail gas treatment step after thermal desorption;

Preferably, the off-gas treatment step is carried out by an off-gas treatment system using the apparatus according to any one of claims 6 to 8;

Preferably, the step of pretreating the organic contaminated soil comprises naturally drying the organic contaminated soil, then crushing, screening and grading;

Preferably, the crushed particles of the organic contaminated soil are classified according to the particle sizes of more than 50mm, 50-30 mm, 30-10 mm and less than 10mm, and the soil with different particle sizes is separately treated during thermal desorption.

A novel organic contaminated soil ex-situ thermal desorption device and a novel organic contaminated soil ex-situ thermal desorption process are characterized by comprising the following steps:

Step one, organic contaminated soil pretreatment

The organic contaminated soil excavated by the excavator is transported to a greenhouse by a muck truck for stacking, is naturally dried, is crushed by a crusher and is screened and classified by a screening machine, and the step is a conventional step for pretreating the organic contaminated soil in the field.

Step two thermal desorption unit process

the thermal desorption unit process consists of a feeding system, a novel thermal desorption device and a discharging cooling system.

Step three tail gas treatment

the tail gas from the kiln tail exhaust pipe consists of a cyclone separator, a spray tower, a bag-type dust remover tail gas fan and an emptying pipe, and the tail gas treatment step is the conventional operation of tail gas treatment in the field.

In the first step, the particle sizes of the particles are graded according to the particle sizes of more than 50mm, 50-30 mm, 30-10 mm and less than 10 mm.

and in the second step, the feeding system consists of a receiving hopper, a feeding belt conveyor, a receiving hopper and a feeding spiral conveyor, all components of the feeding system are conventional parts in the field, and the connection relationship between the components is conventional in the field.

in the second step, the novel thermal desorption device consists of a rotary cylinder with gear transmission, a rolling ring and a riding wheel group, the rotary cylinder with the components is conventional in the field, and the rotary cylinder comprises a kiln head cover and a kiln tail cover.

the inclination angle of the rotary drum is 1-8 degrees, the rotating speed is adjustable at 1-8 rpm, the feeding end is high, and the discharging end is low; a material guide arc-shaped plate is arranged at the feeding end in the rotary cylinder, a combustion chamber is arranged in the middle, refractory casting materials (which are conventional materials in the field and can be obtained commercially) are cast in the inner cylinder, and eight heat-resistant steel plates are uniformly distributed and supported and fixed between the middle combustion chamber and the rotary cylinder to form a thermal desorption cavity; and preserving heat outside the rotary cylinder.

The feeding screw conveyer with a receiving hopper is arranged below the outer end face of the kiln tail cover, the screw conveyer stretches into the position of a guide arc plate of the rotary drum, the exhaust pipe with a valve is arranged at the center, the exhaust pipe stretches into a certain position in the central combustion chamber, and the temperature and pressure measuring device is arranged above the exhaust pipe.

the section of the kiln head cover is concave in the center, refractory casting materials are cast, a burner is arranged in the center of the inner end surface, and a temperature and pressure measuring device is arranged above the burner. The whole kiln head cover is cast by refractory casting material, and the temperature and pressure measuring device can be arranged at any position above the inner end surface of the kiln head cover.

and in the second step, the discharging cooling system consists of a discharging cooler and a discharging belt conveyor, and all components of the discharging cooling system are conventionally arranged in the field.

In the third step, the dust separated by the cyclone separator in the tail gas treatment is discharged to a discharge cooler through a star-shaped discharge valve (the separated dust is equivalent to the soil after thermal desorption treatment); the dust separated by the bag-type dust collector is discharged to a dust discharging belt conveyor to a storage yard (the storage yard connected with the dust discharging belt conveyor can be the same storage yard or not) through a star-shaped discharging valve, and the dust discharging belt conveyor is provided with a water nozzle to moisten soil and reduce raised dust; and discharging the wastewater from the spray tower to a sewage treatment system.

The cooler is a water tank type water-cooling three-stage screw conveyor, and water is introduced into screw shafts of the three-stage screw cooler for cooling; the outlet of the cooler is provided with a water spray head to moisten soil and reduce dust.

A novel organic contaminated soil ex-situ thermal desorption device and a novel organic contaminated soil ex-situ thermal desorption process comprise the following steps:

Step one, organic contaminated soil pretreatment

and stacking the excavated and transported organic contaminated soil in a greenhouse, and respectively stacking the classified organic contaminated soil after natural drying, crushing and screening.

Step two thermal desorption unit process

Organic contaminated soil gets into novel thermal desorption device through feed system, through the arc stock guide in the rotary drum, and feeding thermal desorption intracavity carries out the heat exchange with the hot-blast direct contact who gets into from the kiln tail cover, produces desorption gas, and the soil after thermal desorption is followed the kiln head cover ejection of compact, gets into the cooling machine cooling back and is delivered to the storage yard by ejection of compact band conveyer.

Flame of the kiln head burner is sprayed into the central combustion chamber, the temperature of the combustion chamber reaches 850-1100 ℃, negative pressure is formed at the kiln head cover, and thermal desorption gas is brought into the combustion chamber along with the flame under the negative pressure to be combusted; and adjusting a butterfly valve on an air outlet pipe of the kiln tail cover to enable the interior of the kiln tail cover to be in micro negative pressure, enabling one part of high-temperature flue gas in the central combustion chamber to enter the kiln tail cover, carrying out thermal desorption on the organic contaminated soil in a thermal desorption cavity, and enabling the other part to enter a tail gas treatment process through an exhaust pipe.

Step three tail gas treatment

Most of dust is separated from tail gas discharged from the kiln tail exhaust pipe through a cyclone separator, then the tail gas enters a spray cooling tower and is sprayed and washed by high-pressure water, the temperature is reduced to 130-180 ℃, further dust is removed through a bag-type dust remover, and finally the tail gas is exhausted through a tail gas fan and is discharged after reaching the standard.

a novel organic contaminated soil ex-situ thermal desorption device and a novel organic contaminated soil ex-situ thermal desorption process comprise the following steps:

Step one, organic contaminated soil pretreatment

the organic contaminated soil excavated by the excavator is transported to a greenhouse by a muck truck for stacking, is naturally dried and is screened by a crusher and a screening machine.

Step two thermal desorption unit process

The thermal desorption unit consists of a receiving hopper, a feeding belt conveyer, a novel thermal desorption device, a material cooler and a discharge belt conveyor.

The novel thermal desorption device consists of a rotary cylinder with gear transmission, a rolling ring and a riding wheel group, a kiln head cover and a kiln tail cover.

The rotary cylinder forms a certain inclination angle with the horizontal plane, the feeding end is high, and the discharging end is low; a material guide arc-shaped plate is arranged at the feeding end in the rotary drum, a combustion chamber is arranged in the middle, and eight heat-resistant steel plates are uniformly distributed, supported and fixed between the middle combustion chamber and the rotary drum to form eight thermal desorption cavities; and preserving heat outside the rotary cylinder.

the end face of the kiln tail cover is provided with a feeding screw conveyor with a receiving hopper below, the feeding screw conveyor stretches into the position of a guide arc plate of the rotary cylinder, the center of the feeding screw conveyor is provided with an exhaust pipe with a valve, the exhaust pipe stretches into a certain position in the central combustion chamber, and the temperature and pressure measuring device is arranged above the feeding screw conveyor.

The kiln head kiln has a central concave section, a burner in the center of the end face, and a temperature and pressure measuring device above the burner.

The discharge port of the novel thermal desorption device is provided with a discharge cooler and a discharge belt conveyor.

Step three tail gas treatment

the tail gas treatment system from the kiln tail exhaust pipe consists of a cyclone separator, a spray tower, a bag-type dust remover tail gas fan and an emptying pipe.

The dust separated by the cyclone separator is discharged to the cooler through the star-shaped blanking valve.

the dust separated by the bag-type dust remover is discharged to the dust discharging belt conveyor to the storage yard through the star-shaped discharging valve.

And the wastewater from the spray tower is discharged to a sewage treatment system through a star-shaped blanking valve.

Preferably, in the step one, the grading is divided into particles with the particle size of more than 50mm, 50-30 mm, 30-10 mm and less than 10 mm.

In the preferred scheme, in the second step, the inclination angle of the rotary drum is 1-8 degrees, and the rotating speed is adjustable at 1-8 rpm.

Further preferably, the refractory material is cast in the kiln head cover and the intermediate combustion chamber.

Further preferably, a wedge-shaped closing-in is formed between the kiln head cover and the end face of the cylinder body of the intermediate combustion chamber.

Preferably, in the second step, the cooler is a water tank type water-cooled three-stage screw conveyor, and the screw shafts of the three-stage screw cooler are cooled by water.

Further preferably, a water spray head is arranged at the outlet of the cooler to wet soil and reduce dust.

the preferable scheme is that the novel organic contaminated soil ex-situ thermal desorption device and the process comprise the following steps:

Step one, organic contaminated soil pretreatment

and stacking the excavated and transported organic contaminated soil in a greenhouse, and respectively stacking the classified organic contaminated soil after natural drying, crushing and screening.

Step two thermal desorption unit process

organic contaminated soil is subjected to thermal desorption in a thermal desorption cavity between the rotary drum and the middle combustion chamber through an arc-shaped material guide plate in the hopper, the feeding belt conveyor, the receiving hopper, the feeding screw conveyor and the rotary drum, is directly contacted with hot air entering from a kiln tail cover to generate desorption gas, is discharged through a kiln head cover after thermal desorption of the soil, enters a cooling machine for cooling, and is delivered to a storage yard through the discharging belt conveyor.

Flame of the kiln head burner is sprayed into the central combustion chamber, the temperature of the combustion chamber reaches 850-1100 ℃, negative pressure is formed at the kiln head cover, and thermal desorption gas is brought into the combustion chamber along with the flame under the negative pressure to be combusted; and adjusting a butterfly valve on an air outlet pipe of the kiln tail cover to enable the interior of the kiln tail cover to be in micro negative pressure, enabling one part of high-temperature flue gas in the central combustion chamber to enter the kiln tail cover, carrying out heat exchange with the organic contaminated soil in a thermal desorption cavity, and enabling the other part to enter a tail gas treatment process through an exhaust pipe.

step three tail gas treatment

most of dust is separated from tail gas discharged from the kiln tail exhaust pipe through a cyclone separator, then the tail gas enters a spray cooling tower and is sprayed and washed by high-pressure water, the temperature is reduced to 130-180 ℃, further dust is removed through a bag-type dust remover, and finally the tail gas is discharged after reaching the standard through a tail gas fan.

The invention has the beneficial effects that:

According to the invention, thermal desorption and secondary combustion are integrated in the thermal desorption rotary thermal desorption kiln to be completed, but before the invention, no report is found about the organic contaminated soil remediation process integrating thermal desorption and secondary combustion in the field, and by adopting the rotary thermal desorption kiln and the thermal desorption process with the special structure, heat energy is fully utilized, the energy consumption is low, the structure is compact, the operation and the control are simple, and the investment is reduced; the tail gas is treated and then discharged after reaching the standard. The method is characterized in that thermal desorption and desorption gas combustion are not integrated, two combustors are generally arranged, for example, the two combustors are designed according to the treatment capacity of 10t/h organic polluted soil, the oil consumption of the thermal desorption combustor is 500-600 kg/h, the oil consumption of the organic gas secondary combustor is 180-230 kg/h, the oil consumption of the secondary combustor is about one third of that of thermal desorption, and the energy consumption is more than one third.

Drawings

FIG. 1 is a flow chart of an ectopic thermal desorption process for organic contaminated soil

In the drawings: 1-receiving hopper A, 2-feeding belt conveyor, 3-receiving hopper B, 4-rotary thermal desorption kiln, 5-cyclone separator, 6-star-shaped blanking valve, 7-spray cooling tower, 8-bag dust remover, 9-tail gas fan, 10-star-shaped blanking valve, 11-ash-discharging belt conveyor, 12-star-shaped blanking valve, 13-discharging belt conveyor, 14-discharging cooling machine and 15-tail gas exhaust pipe.

FIG. 2 is a schematic view of a kiln structure dedicated for ex-situ thermal desorption of organic contaminated soil

4-1-butterfly valve, 4-2-kiln tail cover, 4-3-guide arc plate, 4-kiln outer cylinder, 4-5-casting fire-resistant layer, 4-6-combustion chamber cylinder, 4-7-heat-insulating layer, 4-8-kiln head cover, 4-9-burner, 4-10-thermal desorption cavity, 4-11-supporting piece, 4-12-wedge annular air port, 4-13-riding wheel group, 4-14-gear transmission component and 4-15-feeding screw conveyer.

Detailed Description

The present invention will be described in further detail with reference to examples.

Group 1 example, rotary thermal desorption kiln of the invention

The embodiment of the group provides a rotary thermal desorption kiln for thermal desorption of organic contaminated soil. As shown in fig. 1 and 2, the rotary thermal desorption kiln 4 comprises a thermal desorption cavity 4-10 for accommodating and thermally desorbing the organic contaminated soil and a combustion chamber for combusting organic gas generated by thermal desorption, wherein the thermal desorption cavity and the combustion chamber are independent and separated chambers in the thermal desorption rotary thermal desorption kiln; the heat desorption cavity 4-10 is communicated with the combustion chamber through a gas passage, and the gas passage penetrates through the kiln head cover 4-8 and the kiln tail cover 4-2.

the core of the invention is to utilize the heat generated by the combustion of organic pollutants and directly carry out thermal desorption on the organic polluted soil. Whereas the invention patent application 201710713790.1 is an indirect thermal desorption. The direct thermal desorption process mainly depends on the rotary thermal desorption kiln with the innovative structure, and the rotary thermal desorption kiln integrating the combustion chamber and the thermal desorption cavity is never reported in the field.

In some embodiments, the combustion chamber is a hollow cylindrical cavity structure arranged in the center of the rotary thermal desorption kiln; the space between the outer wall of the combustion chamber and the inner wall of the rotary thermal desorption kiln is the thermal desorption cavity; the kiln tail end of the thermal desorption cavity close to the rotary thermal desorption kiln is provided with a wedge-shaped annular air port, the kiln tail end of the combustion chamber close to the rotary thermal desorption kiln is opened in the rotary thermal desorption kiln, and the wedge-shaped annular air port and the kiln tail end of the combustion chamber close to the rotary thermal desorption kiln form the gas channel.

It is seen from fig. 2 that the thermal desorption cavity is an annular structure formed by eight separate fan-shaped cavities when viewed from the kiln tail, and the annular air ports 4-12 of fig. 2 are the kiln tail end and are formed by the exhaust pipe and the combustion chamber at intervals and are used for leading part of hot air of the combustion chamber into the kiln tail cover and entering the eight thermal desorption cavities to carry out direct thermal desorption on soil. The rotary thermal desorption kiln has a high-temperature end as a kiln head end and a low-temperature end as a kiln tail end. The wedge-shaped annular tuyere is arranged at the kiln head. The end surface of the kiln head cover is inwards recessed, and the annular wedge-shaped tuyere is in an upper wedge shape and a lower wedge shape when viewed from the section of the kiln head cover, namely the section shape of the kiln head cover illustrated in figure 1 is wedge-shaped, and the section shape of the tuyere is matched with the section shape of the tuyere, so that the section of the tuyere is in a wedge shape and is in an annular shape when viewed from the end surface of the kiln head cover, and the tuyere is called as a wedge-shaped annular tuyere. And the kiln tail is provided with an annular air port which is formed by a tail exhaust pipe and a combustion chamber inner cylinder at the kiln tail.

In a specific embodiment, the rotary thermal desorption kiln 4 is provided with a negative pressure forming device;

In a preferred embodiment, the negative pressure forming device comprises a butterfly valve 4-1 of an exhaust pipe on a kiln tail cover 4-2 of the rotary thermal desorption kiln, a wedge-shaped annular air opening 4-12 at the kiln tail and a combustor 4-9;

In a more preferable embodiment, a kiln tail cover 4-2 is arranged at the kiln tail of the rotary thermal desorption kiln 4, a tail gas exhaust pipe 15 is arranged on the kiln tail cover 4-2, and a butterfly valve 4-1 is arranged on the tail gas exhaust pipe 15;

The kiln head of the rotary thermal desorption kiln is provided with a kiln head cover 4-8, and the central position of the kiln head cover 4-8 is provided with a burner 4-9;

In the preferred embodiment, the center of the kiln head cover 4-8 is sunken inwards, and temperature and pressure measuring devices are arranged above the kiln head cover 4-8 and the kiln tail cover 4-2.

the burner 4-9 can only be arranged on the kiln hood 4-8, the flame is sprayed towards the inside of the kiln, and negative pressure is formed at the wedge-shaped annular air port 4-12 by utilizing the spraying speed of the flame; the inward depression of the center of the kiln head cover 4-8 means that the outer wall of the inner wall of the kiln head cover is all inward depression, thus a wedge-shaped annular air opening 4-12 can be formed, negative pressure can be generated in the kiln head cover 4-8, and only when negative pressure is formed, hot air in the combustion chamber can enter the heat desorption cavity.

in other embodiments, the shell of the combustion chamber of the rotary thermal desorption kiln 4 is formed by pouring refractory castable into the combustion chamber cylinders 4-6; the thermal desorption cavity of the rotary thermal desorption kiln comprises a rotary cylinder of the rotary thermal desorption kiln, a combustion chamber cylinder body 4-6 and a supporting piece 4-11 for supporting the combustion chamber cylinder body 4-6;

In a preferred embodiment, the inclination angle of the rotary drum is 1-8 degrees, the feeding end is high, and the discharging end is low; the rotating speed of the rotary drum is 1-8 rpm; a material guide arc plate 4-3 is arranged at the feeding end in the rotary cylinder.

in the rotary thermal desorption kiln, eight steel plates are welded between the middle combustion chamber and the rotary cylinder into a whole, so that the combustion chamber and the thermal desorption cavity rotate simultaneously;

The material guide arc-shaped plate is specifically arranged in the depth of about 1.5 meters of the inner cylinder body at the tail part of the rotary thermal desorption kiln, has an arc-shaped spiral structure, is used for guiding flow, and is a conventional part of the rotary thermal desorption kiln in the field.

In a specific embodiment, a support member 4-11 is axially arranged between the shell 4-6 of the combustion chamber and the shell of the rotary cylinder;

In a preferred embodiment, the supporting pieces 4-11 are 8 heat-resistant steel plates uniformly distributed along the circumferential direction of the rotary drum; 8 independent thermal desorption cavities 4-10 are formed among the 8 heat-resistant steel plates.

The rotary drum is provided with gear transmission parts 4-14, rolling rings and idler groups 4-13 which are conventional and are arranged according to the conventional structure of the rotary drum in the field.

Group 2 example, thermal desorption apparatus of the invention

the group of embodiments provides a device for ex-situ thermal desorption of organic contaminated soil, which is characterized by comprising a rotary thermal desorption kiln according to any one of the group 1 embodiments.

In a further embodiment, as shown in FIG. 1, the apparatus further comprises a feed system and an effluent cooling system; the feeding system, the rotary thermal desorption kiln 4 and the discharging cooling system are sequentially connected;

in a preferred embodiment, the feeding system comprises a receiving hopper a1, a feeding belt conveyor 2, a receiving hopper B3, a feeding screw conveyor 4-15;

The discharging cooling system comprises a discharging cooler 14 and a discharging belt conveyor 13;

in a preferred embodiment, the outlet of the receiving hopper a1 is connected to the feed end of the feed belt conveyor 2; the inlet of the receiving hopper B3 is connected with the discharge end of the feeding belt conveyor 2, and the outlet is connected with the feed end of the feeding screw conveyor; the feeding screw conveyer 4-15 is arranged below the end surface of the kiln tail cover of the rotary thermal desorption kiln 4, and the discharge end of the conveyer belt extends into a guide arc plate 4-3 of a rotary cylinder of the rotary thermal desorption kiln 4;

A feed inlet of the discharge cooler 14 is connected with a discharge outlet of a kiln head cover 4-8 of the rotary thermal desorption kiln 4, and the discharge outlet is connected with a discharge belt conveyor 13;

The discharging cooler 14 is a water tank type water-cooling three-stage screw conveyor, and water is introduced into a screw shaft of the discharging cooler for cooling.

The water tank type water-cooling three-stage screw conveyor is simple and small in occupied area and high in cooling efficiency, and can be replaced by other cooling machines such as an external cooling type roller cooling machine and an inner cylinder type air cooling machine.

in still further embodiments, the apparatus further comprises an off-gas treatment system; the tail gas treatment system comprises a cyclone separator 5, a bag-type dust collector 8, a spray cooling tower 7, an ash discharging belt conveyor 11 and a tail gas fan;

The outlet of the cyclone separator 5 is connected with the feed inlet of the discharge cooler 14; the outlet of the bag-type dust collector 8 is connected with an ash discharging belt conveyor 11; the outlet end of the spray cooling tower 7 is connected with a sewage treatment system;

in a preferred embodiment, star-shaped blanking valves 6, 10 and 12 are arranged at the outlet ends of the cyclone separator 5, the bag-type dust collector 8 and the spray cooling tower 7; the ash discharging belt conveyor 11 is provided with a water spray head.

These components that make up the exhaust treatment system: the cyclone 5, bag-type dust collector 8, spray cooling tower 7, ash belt conveyor 11 and tail gas blower and the connections between them are conventional components and common arrangements in the art. The tail gas fan is used for generating power of system tail gas.

the star-shaped blanking valves 12 arranged at the outlet ends of the cyclone separator 5, the bag-type dust collector 8 and the spray cooling tower 7 can be used for blanking and locking air, and can also be replaced by other types of blanking valves, such as: gravity type blanking valve.

Group 3 example thermal desorption process of the invention

the group of embodiments provides a process for ectopic thermal desorption of organic contaminated soil, which is characterized by comprising the following steps of: carrying out thermal desorption on the organic contaminated soil by using the rotary thermal desorption kiln of any one of the group 1 embodiments or the device of any one of the group 2 embodiments.

In a further embodiment, the process further comprises: carrying out a pretreatment step of the organic contaminated soil before thermal desorption and a tail gas treatment step after thermal desorption;

In a preferred embodiment, the off-gas treatment step is carried out by an off-gas treatment system employing the apparatus of any of group 2 embodiments;

In a preferred embodiment, the organic contaminated soil pretreatment step comprises naturally drying the organic contaminated soil, then crushing, screening and grading;

In a preferred embodiment, the crushed particles of the organic contaminated soil are classified according to the particle sizes of more than 50mm, 50-30 mm, 30-10 mm and less than 10mm, and the soil with different particle sizes is separately treated during thermal desorption.

In a most specific embodiment, taking the thermal desorption pentachlorophenol contaminated soil with a particle size of less than 10mm as an example, according to the pilot plant test data, the optimal thermal desorption temperature range of the pentachlorophenol contaminated soil is 350-400 ℃, and the desorption time is 20 min.

as shown in fig. 1 and fig. 2, the thermal desorption rotary thermal desorption kiln 4 is started, the rotating speed is adjusted to enable the soil retention time in the kiln to be 20min, the burner 4-9 is started to enable the rotary thermal desorption kiln to be heated to 850 ℃, the tail gas treatment system is started, meanwhile, the micro negative pressure in the kiln tail cover is adjusted, and the feeding system and the discharging cooling system are started.

Organic contaminated soil with the soil particle size smaller than 10mm after being dried, crushed and screened is added into a receiving hopper 1 through a loading machine, the organic contaminated soil passes through a feeding belt conveyor 2 to the receiving hopper 3, a feeding screw conveyor 4-15 feeds the organic contaminated soil into a rotary thermal desorption kiln 4, the soil is fed into a thermal desorption cavity 4-10 through a guide arc plate 4-3 to exchange heat with hot air, the desorbed soil automatically enters a discharge cooler 14 from a kiln head to be cooled, is sprayed with water to be wet and is sent to a storage yard through a discharge belt conveyor 13.

The tail gas discharged by the exhaust pipe 15 is subjected to gas-powder separation through the cyclone separator 5, the gas enters from the bottom of the spray cooling tower 7 and is cooled by contacting with high-pressure water mist sprayed from the bottom of the spray cooling tower, the gas flows out from the upper part of the spray cooling tower, enters the pulse bag-type dust collector 8 for further dust removal, and is finally emptied by the tail gas fan 9.

The dust at the conical bottom of the cyclone separator 5 is discharged into a discharge cooler 14 through a star-shaped discharge valve 6.

The water at the bottom of the spray cooling tower 7 is discharged to a sewage treatment device through a star-shaped discharging valve 12.

and dust at the lower part of the pulse bag-type dust collector 8 is discharged to an ash discharging belt conveyor 11 through a star-shaped blanking valve 10, is sprayed with water mist to be wetted and then is conveyed to a storage yard.