NL2028848B1 - Flue gas treatment method and device thereof - Google Patents

Abstract

The present invention discloses a flue gas treatment process and device thereof. The device 5 is composed of a roaster, a flue gas conveying pipeline, a calciner, a waste heat boiler, a desulfurization and dust removal device, an induced draft fan and a chimney. Flue gas generated in the production process of the roaster is introduced into a first - layer fire path of the calciner. The flue gas generated in the production process of the roaster is burned in a fire path of the calciner to remove harmful substances of asphalt fume and benzopyrene. The high - temperature 10 flue gas after combustion passes through a collecting flue and then enters the waste heat boiler for heat exchange to produce saturated or superheated steam for production or power generation. To avoid affecting the service life of the calciner due to high temperature of the fire path of the calciner, the calciner is designed with an exogenous volatile passage; and redundant flue gas of the roaster is introduced directly into the collecting flue of the calciner through the exogenous 15 volatile passage of the calciner for incineration.

Description

FLUE GAS TREATMENT METHOD AND DEVICE THEREOF Technical Field The present invention relates to the technical field of environmental protection, in particular to a flue gas treatment method and device thereof.

Background In the production process of a prebaked anode for aluminum, during roasting of carbon blocks, because of insufficient combustion of volatiles, the flue gas contains harmful substances such as asphalt fume, SO: and benzopyrene. The flue gas is generally treated abroad by the incineration method and then desulfurized by the lime - gypsum method.

However, although the incineration method can remove the harmful substances such as asphalt fume, SO: and benzopyrene, the equipment investment is high and an external heat source needs to be consumed to aid combustion. In China, the electric detarring precipitator is used to remove the asphalt fume from the flue gas, and then the lime - gypsum method is used for desulfurization. Although the method can also remove the asphalt fume and SO, the benzopyrene cannot be effectively in treated and a large amount of by - product, gypsum, which contains light fraction, is formed.

Therefore, the technical problem to be urgently solved by those skilled in the art is how to provide a flue gas treatment process and device thereof which can effectively treat the harmful substances such as benzopyrene and have low cost ad low energy consumption.

Summary In view of this, the present invention provides a flue gas treatment device and a flue gas treatment process using the device. A roaster and a calciner are integrated, which saves project floor space and equipment investment cost. Meanwhile, heat energy generated by flue gas combustion can be used to produce steam for electricity generation or sale to produce economic benefits.

To achieve the above purpose, the present invention adopts the following technical solution: A flue gas treatment device comprises a roaster, and a flue gas conveying pipeline, a calciner, a waste heat boiler, a desulfurization and dust removal device, an induced draft fan and a chimney which are successively connected with the roaster.

Further, the above calciner comprises a collecting flue and a plurality of layers of fire paths; the fire paths are arranged on both sides in the calciner; the collecting flue is arranged on one side of the bottom of the calciner, wherein the collecting flue is communicated with a bottom - layer fire path; the conveying pipeline is communicated with a first - layer fire path; the waste heat boiler is connected with the collecting flue.

Further, eight layers of fire paths are arranged, and a second - layer fire path is provided with a temperature measurement device.

In the present invention, the measurement device comprises a measurement end and a display end. The measurement end is used to measure the temperature of the fire paths, and the display end is used to display a temperature number. The measurement device runs through the side wall of the calciner. The measurement end is located on a second - layer fire path, and the display end is located on the outer side wall of the calciner.

Further, the above calciner also comprises an exogenous volatile passage; the exogenous volatile passage comprises an exogenous volatile vertical sub - passage and an exogenous volatile transverse sub - passage which are mutually perpendicular; the exogenous volatile vertical sub - passage is arranged along the longitudinal direction of the calciner; the bottom of the exogenous volatile vertical sub - passage is communicated with one end of the exogenous volatile transverse sub - passage; and the other end of the exogenous volatile transverse sub - passage is communicated with the collecting flue.

Further, an adjusting insertion board is arranged in the middle - upper part of the exogenous volatile vertical sub - passage.

The temperature of the calciner is generated by volatile combustion. When there are many volatiles, heat energy generated by combustion is great, and the temperature the fire path is high. When the temperature of the fire path is too high, redundant volatiles directly enter the collecting flue through the exogenous volatile passage by means of the adjusting insertion board to keep the temperature of the fire path relatively stable.

In the present invention, the collecting flue not only plays the role of collecting the flue gas, but also plays the role of continuous incineration. The exogenous redundant volatiles are continuously incinerated in the collecting flue. When the volatiles that pass through the fire paths reach the collecting flue, the volatiles are almost completely burned.

Another purpose of the present invention is to provide a flue gas treatment method for the above flue gas treatment device, comprising: under the action of the induced draft fan, enabling flue gas generated by the roaster to enter the first - layer fire path of the calciner through the flue gas conveying pipeline; circuitously reaching the bottom - layer fire path by the flue gas through the first - layer fire path, and incinerating the flue gas in the layers of fire paths; making the incinerated flue gas enter the collecting flue; recycling waste heat by the waste heat boiler; then purifying the flue gas by the desulfurization and dust removal device; and discharging the purified flue gas which reaches standards by the induced draft fan to high altitude through the chimney.

Further, when the temperature of the fire path is greater than 1350°C, the adjusting insertion board is opened, and redundant flue gas or volatiles directly enter the collecting flue through the exogenous volatile passage for incineration.

Further, the temperature in the above collecting flue is 200 - 1000°C.

It can be known from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

1. The present invention solves the traditional purification mode of the flue gas in the roaster. The flue gas generated in the production process of the roaster is introduced into the first - layer fire path of the calciner. The flue gas generated in the production process of the roaster is burned in the fire paths of the calciner to effectively remove harmful substances of asphalt fume and benzopyrene. The high - temperature flue gas after combustion passes through the collecting flue and then enters the waste heat boiler for heat exchange to produce saturated or superheated steam for production or power generation.

2. The low - temperature flue gas after waste heat utilization is treated with a set of flue gas treatment device to complete desulfurization, dust removal and purification, thereby saving the investment cost and energy consumption of environmental protection equipment and improving the quality of desulfurization gypsum. The desulfurization gypsum is converted from hazardous waste into ordinary solid waste and directly introduced into the market. Meanwhile, the heat energy generated by flue gas combustion can be used to produce steam for electricity generation or sale to produce economic benefits.

Description of Drawings To more clearly describe the technical solution in the embodiments of the present invention or in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be simply presented below. Apparently, the drawings in the following description are merely the embodiments of the present invention, and for those ordinary skilled in the art, other drawings can also be obtained according to the provided drawings without contributing creative labour.

Fig. 1 is a structural schematic diagram of a flue gas treatment device provided by the present invention; Fig. 2 is a structural schematic diagram of an exogenous volatile passage of a flue gas treatment device provided by the present invention; and Fig. 3 is a structural schematic diagram of an adjusting insertion board of a flue gas treatment device provided by the present invention.

In the figures: 1 - roaster; 2 - flue gas conveying pipeline; 3 - calciner; 4 - first - layer fire path of calciner; 5 - exogenous volatile passage; 51 - exogenous volatile vertical sub - passage; 52 - exogenous volatile transverse sub - passage; 6 - adjusting insertion board; 61 - insertion board box; 62 - insertion board; 7 - collecting flue; 8 - temperature measurement device; 9 - waste heat boiler; 10 - desulfurization and dust removal device; 11 - induced draft fan; 12 - chimney.

Detailed Description The technical solution in the embodiments of the present invention will be clearly and fully described below in combination with the drawings in the embodiments of the present invention. Apparently, the described embodiments are merely part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those ordinary skilled in the art without contributing creative labour will belong to the protection scope of the present invention.

Embodiment 1 Referring to Fig. 1, a flue gas treatment device comprises a roaster 1, a flue gas conveying pipeline 2, a calciner 3, a temperature measurement device 8, a waste heat boiler 9, a desulfurization and dust removal device 10, an induced draft fan 11 and a chimney 12. Eight layers of fire paths 4 are arranged inside the calciner 3, and a collecting flue 7 is arranged on one side of the bottom. The relative distance between the roaster 1 and the calciner 3 shall be as small as possible during construction. A flue outlet of the roaster 1 and an inlet of the first - layer fire path 4 in the calciner 3 are connected through the flue gas conveying pipeline

2. The second - layer fire path 4 is provided with the temperature measurement device 8. A test end of the temperature measurement device is located on the second - layer fire path, and a display end is located on the outer side wall of the calciner 3. The bottom - layer fire path 4 is communicated with the collecting flue 7. The waste heat boiler 9 is installed close to the outlet of the collecting flue 7 of the calciner and connected with the collecting flue 7 through the pipeline. The outlet of the waste heat boiler 9 is connected to the inlet 10 of the desulfurization and dust removal device 10 through a carbon steel pipeline. The outlet of the desulfurization and dust removal device 10 is connected with the inlet of the induced draft fan 11. The outlet of the induced draft fan 11 is connected with the chimney 12.

Referring to Fig. 2, an exogenous volatile passage 5 is also arranged in the calciner 3; the exogenous volatile passage 5 comprises an exogenous volatile vertical sub - passage 51 and an exagenous volatile transverse sub - passage 52 which are mutually perpendicular; the exogenous volatile vertical sub - passage 51 is arranged along the longitudinal direction of the calciner; the bottom of the exogenous volatile vertical sub - passage 51 is communicated with one end of the exogenous volatile transverse sub - passage 52; and the other end of the exogenous volatile transverse sub - passage 52 is communicated with the collecting flue 7.

Referring to Fig. 3, an adjusting insertion board © is arranged on the exogenous volatile vertical sub - passage 51. The adjusting insertion board is built in the middle - upper part of the exogenous volatile vertical sub - passage 51 to divide the exogenous volatile vertical sub - passage 51 into an upper section and a lower section. The adjusting insertion board 6 is composed of an insertion board box 61 and an insertion board 62. The insertion board box 61 is built on the exogenous volatile vertical sub — passage.

Embodiment 2 A flue gas treatment process using the flue gas treatment device provided in embodiment 1 specifically comprises: under the action of the induced draft fan 11, enabling flue gas generated by the roaster 1 to 5 enter the first - layer fire path 4 of the calciner 3 through the flue gas conveying pipeline 2; circuitously reaching the bottom - layer fire path 4 by the flue gas through the first - layer fire path 4, and incinerating the flue gas in the layers of fire paths 4; making the incinerated flue gas enter the collecting flue 7; recycling waste heat by the waste heat boiler 9; then purifying the flue gas by the desulfurization and dust removal device 10; and discharging the purified flue gas which reaches standards by the induced draft fan 11 to high altitude through the chimney 12.

To avoid too high temperature of the fire path of the calciner 3, when the temperature measurement device 41 detects that the temperature of the fire path 4 is greater than 1350°C, the adjusting insertion board 6 is opened, and redundant flue gas or volatiles directly enter the collecting flue 7 through the exogenous volatile passage 5 for incineration.

Embodiment 3 By taking flue gas treatment of a prebaked anode roaster 1 of 10kt/year as an example, the flue gas of 40000 Nm?h /h is produced in the production process at temperature of about 150°C. The flue gas is conveyed to the inlet of the first - layer fire path 4 of the calciner 3 through flue gas conveying pipeline 2, and part of the flue gas enters fire path 4 for combustion. Part of the flue gas enters the collecting flue 7 through the exogenous volatile passage 5 for combustion. The asphalt fume contains a large number of flammable substances with the main component of hydrocarbon. Combustion temperature is controlled at 800 - 1000°C, and oxygen is sufficient. When the residence time of the asphalt fume is about 0.5s, the hydrocarbon substances in the asphalt fume can be fully burned, and the removal efficiency can reach 99%. At the same time, the benzopyrene in the asphalt fume is fully removed, and the removal efficiency can also reach 99%. The mixed flue gas amount after combustion is about 80000 Nm?/h, and the temperature is about 900°C. After heat exchange of the mixed flue gas through the waste heat boiler 9, the temperature of the flue gas is decreased to about 180°C. The flue gas is used as a heat preservation heat source of the conveying pipeline between the roaster 1 and the calciner 3 to ensure that the asphalt fume does not condense in the conveying process. After the heat exchange of the high - temperature flue gas through the waste heat boiler 9, an added steam capacity is about 11T/h. Under the condition of fully benefiting the waste heat, the investment cost of an incinerator is saved. The concentration of the asphalt fume after purification: 5.5 mg/m?®, and benzopyrene content: 0.000005mg/m3. The emission concentrations of the asphalt fume and the benzopyrene generated by the roaster 1 after incineration and waste heat utilization by the calciner 3 are better than the emission standard of pollutants for aluminium industry (GB25465 - 2010) and corresponding limit requirements in the modification list.

Each embodiment in the description is described in a progressive way. The difference of each embodiment from each other is the focus of explanation. The same and similar parts among all of the embodiments can be referred to each other. For a device disclosed by the embodiments, because the device corresponds to a method disclosed by the embodiments, the device is simply described. Refer to the description of the method part for the related part.

The above description of the disclosed embodiments enables those skilled in the art to realize or use the present invention. Many modifications to these embodiments will be apparent to those skilled in the art. The general principle defined herein can be realized in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principle and novel features disclosed herein.

Claims (7)

CONCLUSIONS An apparatus for treating flue gases, the apparatus comprising a burner, and a flue gas transport pipeline, a roaster, a waste heat boiler, a desulfurization and dust removal device, an induced draft fan and a chimney connected sequentially to the burner. The flue gas treatment apparatus of claim 1, wherein the roaster comprises a collector channel and a plurality of fire path layers, the collector channel communicating with a fire path lower layer; the transport pipeline communicates with a first firing path - layer; the waste heat boiler is connected to the collecting duct. The device for treating flue gases according to claim 2, wherein a second fire path layer is provided with a temperature measuring device. The flue gas treatment apparatus of claim 3, wherein the roaster also includes an exogenous volatiles passageway; wherein the exogenous volatiles passageway comprises an exogenous transversely disposed volatiles sub-passage and an exogenous transversely disposed volatiles sub-passage that are perpendicular to each other; wherein the exogenous vertical volatile sub-passage is located in the longitudinal direction of the roaster; wherein the bottom of the exogenous vertical volatile sub-passage communicates with one end of the exogenous transverse volatile sub-passage; and the other end of the exogenous transverse volatile sub-passage communicates with the collecting duct. The flue gas treatment apparatus according to claim 4, wherein a control valve is located in the mid-upper portion of the exogenous volatile vertical sub-passage for volatiles. The flue gas treating method for the flue gas treating apparatus according to claim 5, the apparatus comprising: under the action of the induced draft fan, entering through the flue gas conveying duct flue gas generated by the burner in the first fire path - low; allowing the flue gas to reach the bottom — fire layer through the first fire path — layer in orbit, and burning the flue gas in the layers of the fire paths; introducing the burnt flue gas into the collecting duct, recycling waste heat through the waste heat boiler; then purifying flue gas through the desulfurization and dust removal apparatus; and the discharge of the purified flue gas that complies with the standards through the chimney at a great height by the induced draft fan. The flue gas treatment method according to claim 6, wherein when the temperature of the firing path exceeds 1350°C, the control valve is opened and excess flue gas or volatiles pass directly through the exogenous volatiles passage into the collection channel for combustion.