CN104214770A - A comprehensive utilization system and method for selenium extraction in stone coal power generation - Google Patents

Abstract

A system and method for comprehensive utilization of selenium in stone coal power generation. The system includes a fluidized bed boiler, a superheater and an economizer arranged in sequence in the tail flue, and a high-temperature boiler in different temperature ranges at the outlet of the tail flue. Dust removal equipment and low temperature dust removal equipment, the fluidized bed boiler includes a furnace, a separator connected to the top of the furnace, and a circulating ash discharge controller connected to the separator and the furnace; the controller on the top of the circulating ash discharge controller has an ash inlet pipe and a separator The riser pipe of the feeder at the bottom is shared or branched from the riser pipe of the feeder; the outlet of the circulating ash discharge controller is arranged with a return inclined pipe and a low-temperature ash discharge pipe. The outlet is divided into two routes, one is connected to the circulating ash conveying system, and the other is directly discharged; the invention also provides a method for the comprehensive utilization of the system for selenium extraction in stone coal power generation; it has the advantages of low energy consumption, high selenium extraction efficiency, simple system, and low investment in selenium extraction. Small scale, low selenium escape rate, low equipment investment and other advantages.

Description

A comprehensive utilization system and method for selenium extraction in stone coal power generation

technical field

The invention belongs to the technical field of comprehensive utilization of stone coal, and in particular relates to a comprehensive utilization system and method for selenium extraction by stone coal power generation.

Background technique

Stone coal is a kind of polymetallic symbiotic shale mine, which was formed in the Early Proterozoic and Early Paleozoic. It has the characteristics of high ash, high sulfur, low calorific value and high hardness. It can be used as low-quality fuel and extract selenium and vanadium from it. , uranium, molybdenum, nickel, copper, cobalt and other minerals are distributed in more than 20 provinces including Hunan, Hubei, Sichuan, Guizhou, Zhejiang, Guangxi, Jiangxi, Anhui, Shanxi, Shanxi, Henan and Gansu.

Circulating ash refers to the material in the external circulation collected by the cyclone separator of the circulating fluidized bed boiler. Sufficient circulating ash in the dense-phase area of the circulating fluidized bed is an effective means to control the bed temperature from being too high. On the contrary, if the circulating ash If the amount is too much, it will lead to low bed temperature and insufficient combustion, resulting in reduced combustion efficiency. At the same time, it will cause problems such as increased wear and increased energy consumption of the fan. Because stone coal fuel has the characteristics of high ash, low calorific value and high temperature explosion, the amount of circulating ash and fly ash after burning stone coal is relatively large.

Selenium is an essential trace element for plants, animals, and humans, but excessive intake can also cause poisoning. Most of the selenium in coal is distributed in pyrite, and selenium is also contained in clay minerals and organic components. Selenium dioxide is mainly used in the electrolytic manganese industry. About 1 kg of selenium dioxide is needed to produce one ton of electrolytic manganese (each system is slightly different), and the electrolytic manganese industry accounts for about 80% of the selenium dioxide consumption. Secondly, it is used in the feed industry to produce sodium selenite, and now it is also used as a raw material for foliar selenium fertilizer of selenium-containing crops in the agricultural industry.

Selenium migrates during coal combustion, more than 75% of selenium in coal volatilizes, and 79% of selenium enriched in fly ash is distributed in fine particles <2μm. Selenium emissions from coal-fired power stations account for more than 50% of global anthropogenic selenium emissions. Selenium poisoning caused by coal burning is mainly caused by burning high-selenium stone coal, which releases _SeO2 in the air and exists in aerosol state. In areas where high-selenium stone coal is burned, the concentration of selenium in the air can be as high as 0.6mg/m ³ , and selenium poisoning incidents of humans and animals are prone to occur.

Contents of the invention

In order to solve the above-mentioned problems in the prior art, the object of the present invention is to provide a comprehensive utilization system and method for selenium extraction in stone coal power generation, which has high boiler efficiency, low energy consumption, high selenium extraction efficiency, simple system, and large investment scale for selenium extraction. Small size, low selenium escape rate, small footprint, and low equipment investment.

To achieve the above object, the present invention adopts the following technical solutions:

A comprehensive utilization system for selenium extraction by stone coal power generation, including a fluidized bed boiler for burning stone coal fuel, a superheater 8 and an economizer 9 arranged in sequence in the flue at the tail of the fluidized bed boiler, and also includes a fluidized bed boiler sequentially arranged in the fluidized bed boiler The high-temperature dedusting equipment 5 and low-temperature dedusting equipment 3 in different temperature ranges at the flue outlet at the tail of the chemical bed boiler, and the air preheater 4 arranged between the high-temperature dedusting equipment 5 and the low-temperature dedusting equipment 3 are arranged after the low-temperature dedusting equipment 3 in sequence The induced draft fan 2 and the chimney 1; the fluidized bed boiler includes a furnace 12, an air chamber 13 communicating with the bottom of the furnace 12, a separator 10 communicating with the top of the furnace 12, and a circulating ash discharge communicating with the separator 10 and the furnace 12 Controller 11; the controller ash inlet pipe 17 at the top of the circulating ash discharge controller 11 is shared with the feeder riser 14 at the bottom of the separator 10, that is, the feeder riser 14 also serves as the controller ash inlet pipe 17 or Lead a branch from the return standpipe 14 as the controller ash inlet pipe 17; the outlet of the circulating ash discharge controller 11 is arranged with a return inclined pipe 17 and a low-temperature ash discharge pipe 15, and the return inclined pipe 17 is connected to the furnace close In the phase area, the outlet of the low-temperature ash discharge pipe 15 is divided into two paths, one of which is connected to the circulating ash conveying system, and the low-temperature circulating ash is transported to the slag bin by the circulating ash conveying system; the other is directly discharged as an accidental ash discharge.

The high-temperature dust removal equipment 5 is arranged in the area where the flue gas temperature is above 360° C. after the economizer 9 , and the low-temperature dust removal equipment 3 is arranged in the area where the normal exhaust gas temperature is 130° C. after the high-temperature dust removal equipment 5 .

It also includes an ash hopper heating system 6 arranged at the bottom of the high-temperature dust removal equipment 5 and the low-temperature dust removal equipment 3 .

The ash hopper heating system 6 is a circulation type or an independent type. The ash hopper heating system 6 absorbs the heat of the ash hopper of the high-temperature dust collector and is used to heat the ash hopper of the low-temperature dust collector. The independent type is the high-temperature dust removal equipment 5 And the low-temperature dust removal equipment 3 are respectively provided with an ash hopper heating system 6 .

The superheater 8 has one or more stages.

The economizer 9 has one or more stages.

The number of the separators 10 is 2, 3, 4 or 6.

The method for comprehensively utilizing the above-mentioned system for generating selenium by stone coal power generation. The fluidization wind enters the furnace 12 from the air chamber 13 to provide fluidization power and partial combustion oxygen for the stone coal fuel. After being burned in the separator 10 for gas-solid separation; after the clean flue gas comes out of the separator 10, it passes through the superheater 8 and the economizer 9 in sequence, and then enters the high-temperature dust collector 5 to remove a large amount of selenium-free or a small amount of selenium-containing fly After that, it enters the air preheater 4 for heat exchange and cooling. After the temperature drops to 130°C in the normal exhaust gas temperature range, the low-temperature flue gas enters the low-temperature dust collector 3 for secondary dust removal, and collects the fly ash enriched in selenium dioxide. The clean flue gas is sent into the chimney 1 through the induced draft fan 2; the circulating ash separated by the separator 10 enters the circulating ash discharge controller 11 through the ash inlet pipe 17 of the controller, and the circulating ash discharge controller 11 passes through the inclined return pipe 17 and the low temperature The ash discharge pipe 15 sends the circulating ash into the furnace 12 and the slag bin respectively.

Compared with the prior art, the present invention has the following advantages:

1. The circulating fluidized bed boiler of the present invention is equipped with a circulating ash discharge controller, which is used to discharge excessive circulating ash when the circulating fluidized bed boiler burns stone coal. It can solve the problems of low bed temperature, insufficient combustion, reduced combustion efficiency, increased wear, and increased fan energy consumption caused by excessive circulating ash. At the same time, this part of ash does not contain or only contains a small amount of selenium, which is also helpful for improving the efficiency of selenium extraction. help.

2. The present invention adopts a combination of high and low temperature dust removal equipment. The high temperature dust collector is arranged in the area above 360°C at the flue outlet behind the furnace, and the dust removal efficiency is designed to be not less than 90%, which is used to remove selenium dioxide that does not contain or only contains a small amount of selenium dioxide. The low-temperature dust collector is arranged in the normal exhaust temperature area of 130°C after the high-temperature dust collector (lower than the sublimation temperature of selenium dioxide at 315°C), and is used to collect fly ash rich in selenium dioxide, so it has a higher Selenium-enhancing efficiency.

3. The present invention only slightly adjusts the layout of the heating surface in the tail flue of the conventional fluidized bed boiler, and moves the air preheater to the high-temperature electrostatic precipitator, so the flue arrangement is convenient and the system is simple.

4. The present invention utilizes the characteristic that selenium dioxide will be attached to fine ash particles when it is lower than 315°C, so the selenium escape rate is relatively low.

5. The present invention does not need to arrange an independent separation system, occupies a small space, and has low equipment investment.

In summary, this system has the advantages of high boiler efficiency, low energy consumption, high selenium extraction efficiency, simple system, small investment scale for selenium extraction, low selenium escape rate, small occupied space, and low equipment investment.

Description of drawings

Fig. 1 is a schematic diagram of the system of the present invention.

Figure 2 is a schematic diagram of a circulating ash discharge controller.

Figure 3 is a schematic diagram of the ash hopper heating system (circulation type).

Figure 4a is a schematic diagram of the arrangement of two separators.

Figure 4b is a schematic diagram of the arrangement of three separators.

Figure 4c is a schematic diagram of the arrangement of four separators.

Figure 4d is a schematic diagram of the arrangement of six separators.

In the figure: 1. Chimney; 2. Induced fan; 3. Low temperature dust collector; 4. Air preheater; 5. High temperature dust collector; 6. Ash hopper heating system; 7. Main steam header; 8. Superheater; 9. Economizer; 10. Separator; 11. Circulating ash discharge controller; 12. Furnace; 13. Air chamber; 14. Feeder standpipe 15. Low temperature ash discharge pipe 16. Controller ash inlet pipe 17. Return ramp.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1 and Figure 2, a comprehensive utilization system for stone coal power generation and selenium extraction includes a fluidized bed boiler for burning stone coal fuel, a superheater 8 and a coal-saving boiler arranged in sequence in the tail flue of the fluidized bed boiler The device 9 also includes high-temperature dedusting equipment 5 and low-temperature dedusting equipment 3 sequentially arranged in different temperature regions of the tail flue outlet of the fluidized bed boiler, and an air preheater 4 arranged between the high-temperature dedusting equipment 5 and the low-temperature dedusting equipment 3 , the induced draft fan 2 and the chimney 1 arranged in sequence after the low-temperature dedusting equipment 3; 10 is a circulating ash discharge controller 11 connected to the furnace 12; the controller ash inlet pipe 17 at the top of the circulating ash discharge controller 11 is shared with the returner standpipe 14 at the bottom of the separator 10, that is, the returner standpipe 14 It is also used as the ash inlet pipe 17 for the controller or branched from the standpipe 14 of the return feeder as the ash inlet pipe 17 for the controller; the outlet of the circulating ash discharge controller 11 is arranged with a return inclined pipe 17 and a low temperature ash discharge pipe 15, The return inclined pipe 17 is connected to the dense-phase area of the furnace, and the outlet of the low-temperature ash discharge pipe 15 is divided into two routes, one of which is connected to the circulating ash conveying system, and the low-temperature circulating ash is transported to the slag bin by the circulating ash conveying system; the other is directly discharged, Discharge ash as an accident.

As a preferred embodiment of the present invention, the high-temperature dust removal equipment 5 is arranged in the area where the flue gas temperature is above 360°C after the economizer 9, and the low-temperature dust removal equipment 3 is arranged in the area where the normal exhaust gas temperature is 130°C after the high-temperature dust removal equipment 5 .

As a preferred embodiment of the present invention, it also includes an ash hopper heating system 6 arranged at the bottom of the high-temperature dust removal equipment 5 and the low-temperature dust removal equipment 3 .

Further, the ash hopper heating system 6 is a circulating type or an independent type, and the independent type, that is, the high-temperature dust removal equipment 5 and the low-temperature dust removal equipment 3 are respectively provided with an ash hopper heating system 6 . As shown in Figure 3, it is a circulating ash hopper heating system, that is, the ash hopper heating system 6 absorbs the heat of the ash hopper of the high-temperature dust collector to heat the ash hopper of the low-temperature dust collector, and reasonably designs and controls the temperature of the ash hopper to prevent ash from hardening.

As a preferred embodiment of the present invention, the superheater 8 has one or more stages.

As a preferred embodiment of the present invention, the economizer 9 has one or more stages.

As a preferred embodiment of the present invention, the number of the separators 10 is 2, 3, 4 or 6. As shown in Fig. 4a, Fig. 4b, Fig. 4c and Fig. 4d, they are schematic diagrams of the arrangement of 2, 3, 4 and 6 separators 10 around the furnace 12, respectively.

The present invention also provides a method for comprehensively utilizing the above system for selenium extraction in stone coal power generation. The fluidization wind enters the furnace 12 from the air chamber 13 to provide fluidization power and partial combustion oxygen for the stone coal fuel. After being burned in the furnace 12, it enters the separator 10 for gas-solid separation; after the clean flue gas comes out of the separator 10, it passes through the superheater 8 and the economizer 9 in sequence, and enters the high-temperature dust collector 5 to remove a large amount of non-selenium or a small amount of selenium. Selenium fly ash then enters the air preheater 4 for heat exchange and cooling. After the temperature drops to 130°C in the normal exhaust temperature range, the low-temperature flue gas enters the low-temperature dust collector 3 for secondary dust removal, and the fly ash enriched in selenium dioxide is collected. Finally, the clean flue gas is sent into the chimney 1 through the induced draft fan 2; the circulating ash separated by the separator 10 enters the circulating ash discharge controller 11 through the ash inlet pipe 17 of the controller, and the circulating ash discharge controller 11 passes through the inclined return pipe 17 and the low-temperature ash discharge pipe 15 send the circulating ash into the furnace 12 and the slag bin respectively.

Claims (8)

1. A comprehensive utilization system for selenium extraction by stone coal power generation, comprising a fluidized bed boiler for burning stone coal fuel, a superheater (8) and an economizer (9) arranged successively in the tail flue of the fluidized bed boiler, It is characterized in that it also includes high-temperature dedusting equipment (5) and low-temperature dedusting equipment (3) arranged sequentially in different temperature regions of the flue outlet at the tail of the fluidized bed boiler, and arranged between the high-temperature dedusting equipment (5) and low-temperature dedusting equipment (3) ) between the air preheater (4), the induced draft fan (2) and the chimney (1) arranged in turn after the low temperature dedusting equipment (3); the fluidized bed boiler includes a furnace (12), and a furnace (12 ) the air chamber (13) communicated at the bottom, the separator (10) communicated with the top of the furnace (12) and the circulating ash discharge controller (11) communicated with the separator (10) and the furnace (12); The controller ash inlet pipe (17) at the top of the discharge controller (11) is shared with the feeder vertical pipe (14) at the bottom of the separator (10), that is, the feeder vertical pipe (14) also serves as the controller ash inlet pipe (17) or lead a branch from the feeder standpipe (14) as the controller ash inlet pipe (17); the outlet of the circulating ash discharge controller (11) is arranged with a return inclined pipe (17) and a low-temperature ash discharge The pipe (15) and the return inclined pipe (17) are connected to the dense-phase area of the furnace. The outlet of the low-temperature ash discharge pipe (15) is divided into two paths, one of which is connected to the circulating ash conveying system, and the low-temperature circulating ash is fed by the circulating ash conveying system. Transported to the slag bin; directly discharged all the way, as an accidental ash discharge. 2. A comprehensive utilization system for stone coal power generation and selenium extraction according to claim 1, characterized in that: the high-temperature dust removal equipment (5) is arranged in the area where the flue gas temperature is above 360°C after the economizer (9), and the The low-temperature dedusting equipment (3) is arranged behind the high-temperature dedusting equipment (5) in the normal exhaust gas temperature area of 130°C. 3. A comprehensive utilization system for stone coal power generation selenium extraction according to claim 1, characterized in that: it also includes an ash hopper heating system (6) arranged at the bottom of the high temperature dust removal equipment (5) and the low temperature dust removal equipment (3) . 4. a kind of stone coal power generation selenium comprehensive utilization system according to claim 3, is characterized in that: described ash hopper heating system (6) is circulation type or independent type, and described circulation type is ash hopper heating system ( 6) Absorb the heat from the ash hopper of the high-temperature dust collector to heat the ash hopper of the low-temperature dust collector. The independent high-temperature dust removal equipment (5) and the low-temperature dust removal equipment (3) are respectively equipped with ash hopper heating systems (6). 5 . The comprehensive utilization system for selenium extraction by stone coal power generation according to claim 1 , characterized in that: the superheater ( 8 ) has one or more stages. 6 . 6. A comprehensive utilization system for selenium-enhancing stone coal power generation according to claim 1, characterized in that: the economizer (9) has one or more stages. 7. A comprehensive utilization system for selenium extraction by stone coal power generation according to claim 1, characterized in that: the number of said separators (10) is 2, 3, 4 or 6. 8. The method for comprehensively utilizing the system of claim 1 for selenium extraction in stone coal power generation is characterized in that: the fluidization wind enters the furnace (12) from the air chamber (13) to provide fluidization power and partial combustion for the stone coal fuel Oxygen content, stone coal burns in the furnace (12) of the fluidized bed boiler, and then enters the separator (10) for gas-solid separation; after the clean flue gas comes out of the separator (10), it passes through the superheater (8) and The economizer (9) enters the high-temperature dust collector (5) to remove a large amount of fly ash that does not contain selenium or contains a small amount of selenium, and then enters the air preheater (4) for heat exchange and cooling, and the temperature drops to 130°C in the normal exhaust gas temperature area Finally, the low-temperature flue gas enters the low-temperature dust collector (3) for secondary dust removal, collects the fly ash enriched with selenium dioxide, and finally sends the clean flue gas into the chimney (1) through the induced draft fan (2); the separator (10 ) separated circulating ash enters the circulating ash discharge controller (11) through the controller ash inlet pipe (17), and the circulating ash discharge controller (11) passes through the inclined return pipe (17) and the low temperature ash discharge pipe (15) respectively The circulating ash is sent into the furnace (12) and the slag bin.