CN107233792B - A common method and system for high solid-gas ratio dehumidification and desulfurization based on micronized limestone - Google Patents

Abstract

The invention relates to a high solid-gas ratio dehumidifying and desulfurizing commonness method and system based on micro powder limestone, wherein the micro powder limestone enters a humidifying and mixing system through a buffer bin and a metering system, and simultaneously enters a mixing and humidifying system and atomized water and circulating desulfurized ash, the micro powder limestone is fully humidified, activated and homogenized in the humidifying and mixing system to improve the desulfurizing reaction activity, the micro powder limestone is fluidized and conveyed through a fluidizing tank, the material is fully dispersed and enters a high solid-gas ratio reactor during conveying, the material does irregular turbulent motion along with hot flue gas in the reactor, free humidified water in the micro powder limestone is evaporated by the sensible heat of the flue gas in the motion process, ideal temperature and humidity conditions for the desulfurizing reaction are gradually formed on the surfaces of micro powder limestone particles, and SO in the flue gas ₂ Reacting with fine particle limestone to generate desulfurized gypsum, and discharging the purified flue gas into the atmosphere; the flue gas desulfurization efficiency of the invention is more than or equal to 95 percent, the investment is saved, the waste water is zero, the flue gas moisture discharge is small, the water content of the desulfurized gypsum is less than or equal to 3 percent, and the effective utilization of solid waste resources can be realized.

Description

A common method and system for high solid-gas ratio dehumidification and desulfurization based on micronized limestone

technical field

The invention belongs to the technical field of flue gas desulfurization, and in particular relates to a common method and system for high solid-gas ratio dehumidification and desulfurization based on fine powder limestone.

Background technique

A large amount of SO ₂ emissions will cause great harm to the environment and human beings. Now China is the third largest acid rain area after Europe and North America, and the area of acid rain accounts for about 30% of the country's land resources.

As environmental problems become more and more prominent on a global scale, countries around the world have also stepped up efforts in environmental governance. Flue gas desulfurization technology (FGD) - wet desulfurization is currently the most common technology and method to control SO ₂ .

Although this type of desulfurization technology has high desulfurization efficiency, it generally has the following defects: (1) In terms of environmental protection effects: wet desulfurization tail gas has low temperature, high humidity, and secondary pollution such as residual fine coal ash and newly formed sulfate particles Some experts have shown that such substances are easy to form aerosols when they are discharged into the atmosphere, thereby aggravating urban smog. The tower is easy to scale, and it is easy to generate desulfurization wastewater; (3) In terms of solid waste resource utilization: the desulfurization gypsum produced by wet desulfurization still has a moisture content of about 10-15% after pressure filtration, which limits its use as a bulk solid waste Potential for resource utilization; (4) Investment and operating costs: The existing wet desulfurization technologies generally have the disadvantages of large floor area, high initial investment, and high operation and maintenance costs.

Contents of the invention

In order to overcome the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a common method and system for high solid-gas ratio dehumidification and desulfurization based on micropowdered limestone. The treatment greatly improves the reaction activity, and can achieve the same flue gas desulfurization efficiency (≥98%) as the wet method under dehumidification conditions. The desulfurization wastewater is produced at the same time as it has the characteristics of low moisture content in the tail flue gas, which can effectively avoid Wet flue gas has a negative effect on the formation of urban smog. The proportion of desulfurized gypsum in waste residue is ≥90%, and the moisture content is ≤2%. It can be directly used as high-performance recycled gypsum to realize large-scale resource utilization in the field of building materials.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A high solid-gas ratio dehumidification and desulfurization common method based on micropowdered limestone, comprising the following steps:

Step 1: Micropowdered limestone is stored in the material buffer bin;

Step 2: Design a measuring system under the material buffer silo to measure the fine powder limestone. After the metering, it enters the mixing humidification system. At the same time, the circulating desulfurization ash and humidifying water also enter the mixing humidifying system. After the mixing humidification In the system, the materials are fully mixed and humidified;

The third step: the humidified mixed material is fully fluidized through the fluidization tank and then enters the high solid-gas ratio reactor;

Step 4: Mix the material and flue gas components in the high solid-gas ratio reactor, and the water will change from liquid to gas under the action of hot flue gas, forming a certain wet environment on the surface of the _particles . Limestone reacts to generate desulfurization gypsum to achieve the purpose of desulfurization;

Step 5: After the material reacts in the high solid-gas ratio reactor, it forms desulfurization ash and enters the primary separator together with the flue gas. The material in the primary separator is separated and enters the ash return buffer bin; part of the material enters the dust collection together with the flue gas System, after being filtered and cleaned, it is collected into the ash return buffer bin; the purified flue gas is discharged into the atmosphere through the induced draft fan;

Step 6: The circulating desulfurized ash entering the ash return buffer bin is metered by the metering system under the bin and then enters the mixing humidification system, where it is mixed with desulfurizer and water, so that the process forms a cycle;

Step 7: When the circulating desulfurization ash reaches the high material level in the ash return buffer bin, the desulfurization ash is discharged to form the final desulfurization ash.

The average particle size of the particulate limestone is less than 6 μm, the moisture content of the material after humidification in the mixing humidification system is controlled at 4-6%, and the temperature of the flue gas entering the high solid-gas ratio reactor is not lower than 150°C. The temperature of the flue gas exiting the high solid-gas ratio reactor is not higher than 65°C, and the humidity is not higher than 50%. The dust concentration inside the high solid-gas ratio reactor gas is up to 3000g/Nm ³ , and the separation efficiency of the primary separator is 50-90%, and the final desulfurization ash moisture is not more than 3%.

The present invention also provides a high solid-gas ratio dehumidification and desulfurization common system based on micronized limestone, including:

Material buffer bin for storing fine powder limestone;

Ash return buffer bin for storing circulating desulfurization ash;

A metering system for metering fine powdered limestone and circulating desulfurization ash fed into the mixing humidification system;

A mixing and humidifying system for mixing and humidifying the micropowdered limestone and circulating desulfurization ash;

a water system for supplying water to the mixing humidification system;

A high solid-gas ratio reactor for desulfurizing the mixed humidified material and flue gas, and the high solid-gas ratio reactor is connected with the mixed material humidification system and the flue gas pipeline;

A primary separator and a dust collection system for material separation connected to the flue gas outlet of the high solid-to-gas ratio reactor, the material outlets of the primary separator and dust collection system are connected to the ash return buffer bin;

And, an induced draft fan that provides power is connected with the flue gas outlet of the dust collection system.

A pneumatic activation system is set under the material buffer bin to prevent the normal unloading caused by the hardening and agglomeration of fine powder limestone.

The metering system is an adjustable metering system, and the metering method is spiral metering or sealed belt metering.

The mixing humidification system is an online mixing humidification, and the process is continuous.

The system of the present invention may also include:

A fluidization tank for fluidizing the mixed humidification material before being sent into the high solid-to-gas ratio reactor.

The fluidization tank is pneumatic fluidization, and the material is in a suspended state after fluidization.

The dust collection system is a bag dust collector, such as a double-filter coated bag dust collector.

Compared with prior art, the beneficial effect of the present invention is:

1) High desulfurization efficiency;

2) Small investment;

3) Zero waste water generation;

4) The moisture content of flue gas is small;

5) The moisture content of desulfurization ash is low.

To sum up, the desulfurization efficiency of the present invention can reach more than 95%, and has high desulfurization efficiency, low investment, no waste water in production, low humidity discharge of flue gas, and low moisture content of desulfurization ash.

Description of drawings

Fig. 1 is a block diagram of the flue gas desulfurization process of the present invention.

Fig. 2 is a structural schematic diagram of Form 1 of the flue gas desulfurization system of the present invention.

Figure 3 shows the relationship between flue gas desulfurization efficiency and calcium-sulfur ratio in the high solid-gas ratio dehumidification and desulfurization pilot test platform.

Figure 4 shows the relationship between flue gas desulfurization efficiency and humidity in the high solid-gas ratio dehumidification desulfurization pilot platform experiment.

Figure 5 shows the relationship between flue gas desulfurization efficiency and SO ₂ inlet concentration in the high solid-gas ratio dehumidification and desulfurization pilot test platform.

Detailed ways

The implementation of the present invention will be described in detail below in conjunction with the drawings and examples.

As shown in Figure 1, a high solid-gas ratio dehumidification and desulfurization common method based on micronized limestone includes the following steps:

Step 1: Store desulfurizing agent micropowdered limestone in the material buffer bin. Micropowdered limestone is an ultrafine calcium-based desulfurizing agent whose mineral is CaCO ₃ , with an average particle size of less than 6 μm.

Step 2: Design a metering system under the buffer bin to measure the desulfurizer, and then enter the mixing humidification system. At the same time, circulating desulfurization ash and humidifying water also enter the mixing humidification system. In the mixing humidification system Inside, the material is fully mixed and humidified. The mixing humidification system is an online mixing humidification process. The process is continuous. After humidification, the moisture content of the material is controlled at 4-6%, and the material fluidity is good.

Step 3: The humidified mixed material is fully fluidized through the fluidization tank and then enters the high solid-gas ratio reactor. The fluidization tank is pneumatic fluidized, and the material is in a suspended state after fluidization.

Step 4: In the high solid-gas ratio reactor, the material is mixed with the flue gas components at a temperature not lower than 150°C, and the moisture changes from liquid to gaseous under the action of hot flue gas, forming a certain wet environment near the surface of the particles, SO _2. In this wet environment, it reacts with fine powdered limestone to form solid matter to achieve the purpose of desulfurization.

Step 5: The material reacts in the high solid-gas ratio reactor. The dust concentration inside the high solid ratio reactor gas can reach up to 3000g/Nm ³ . After the reaction, desulfurization ash is formed and enters the primary separator together with the flue gas. Part of the material is separated into the ash return buffer bin. The separation efficiency of the primary separator is 50-90%. For bag dust collectors, such as double-coated high-efficiency dust collectors. The temperature of the purified flue gas is not higher than 65°C, the humidity is not higher than 50%, and it is discharged into the atmosphere through the induced draft fan.

Step 6: The circulating desulfurized ash entering the ash return buffer bin is metered by the metering system under the bin, and then enters the mixing humidification system, where it is mixed with desulfurizer and water, and the process forms a cycle at this point. The metering system can be an adjustable meter, and the metering method can be spiral metering, sealed belt metering or other adjustable dynamic metering methods.

Step 7: When the circulating desulfurization ash reaches a high material level in the ash return buffer bin, the desulfurization ash is discharged to form the final desulfurization ash. The moisture content of the desulfurization ash is not more than 3%, and the desulfurization efficiency of the system is greater than 95%.

The present invention also provides a corresponding system, including the following forms.

As shown in Figure 2, it is one of the forms of the system of the present invention:

The fine powder limestone is stored in the material buffer bin 01, and the manual gate valve 02 is installed under the warehouse. The manual gate valve 02 is in the normally open state, and it is closed for maintenance when there is a problem in the subsequent system. The lower part of manual gate valve 02 is equipped with a metering system composed of frequency conversion impeller feeder 03 and screw metering scale 04. The desulfurization agent is accurately metered and then enters the humidification mixer 05. At the same time, the desulfurization circulating ash and humidification water also enter the humidification mixer. Wet mixer 05, the materials in the humidifying mixer 05 are fully mixed, humidified and activated and then enter the fluidization tank 06, and the power of the fluidization tank comes from the fluidization fan 07. The material is transported to the material spreading box 08 through the fluidization tank 06, and then enters the high solid-gas ratio reactor 09 after being dispersed by the material spreading box 08. In the high solid-gas ratio reactor 09, the material and flue gas components are mixed, and the moisture changes from liquid to gas under the action of hot flue gas, forming a certain wet environment near the surface of the particles. In this wet environment, SO ₂ and ultrafine calcium The base material reacts to form a solid substance to achieve the purpose of desulfurization. After the desulfurization agent reacts, the circulating ash is formed and enters the primary separator 11 with the wind, and some materials are separated in the primary separator 11, and are discharged into the ash return buffer bin 15 through the impeller feeder 12 for buffer storage. The rest of the desulfurizing agent enters the bag filter 13 together with the wind, and the desulfurizing agent is completely collected in the bag filter 13, and enters the ash return buffer bin 15 through the impeller feeder 14. There is a manual gate valve 16 under the warehouse, which is in the normally open position and closed for maintenance when the lower process fails. The lower part of the manual gate valve 16 is provided with double material paths, one of which is equipped with an electric gate valve 18 to discharge the desulfurized ash, and one of the other is equipped with an electric gate valve 17 to control the disconnection of the desulfurized ash cycle. The lower part of the electric gate valve 17 is equipped with a metering system composed of a frequency conversion impeller feeder 19 and a screw feeder scale 20, which accurately measures the circulating desulfurization ash and then enters the humidifying mixer 05 to form a cycle of desulfurization ash. The gas treated by the bag filter 13 is discharged into the atmosphere by the induced draft fan 21 .

The desulfurization efficiency of the present invention is with calcium-sulfur ratio, humidity and SO _The inlet concentration experiment is as follows:

Under the conditions of flue gas inlet temperature of 180±10°C and flue gas volume of 300m ³ /h, different calcium-sulfur ratios, different humidity levels, and different SO ₂ inlet concentrations were selected for experiments on a high-solid-gas ratio dehumidification and desulfurization pilot platform to investigate The relationship between flue gas desulfurization efficiency and the above factors is shown in Figure 3, Figure 4 and Figure 5. As the calcium-sulfur ratio increases from 50 to 250, the flue gas SO ₂ concentration decreases from 72 mg/Nm ³ to 5 mg/Nm ³ , and the desulfurization efficiency increases from 93% to 99.5%. When the calcium-sulfur ratio reaches 250, it has reached the flue gas desulfurization efficiency of the limestone-gypsum method, fully meeting the requirements of ultra-clean emissions. Under the same calcium-sulfur ratio, the flue gas desulfurization efficiency increases from 85% to 96% when the humidity increases from 16% to 39%, but if the humidity continues to increase, the growth trend of the flue gas desulfurization efficiency slows down. It is advisable that the humidity of the flue gas should not exceed 50% under on-site working conditions. With the increase of the concentration of sulfur dioxide in the flue gas, the outlet emission values were kept below 10mg/Nm ³ stably.

Claims (5)

1. A common method for high solid-gas ratio dehumidification and desulfurization based on micropowdered limestone, the system based on which includes: A material buffer bin for storing micropowdered limestone; a pneumatic activation system is set under the material buffer bin to prevent normal unloading caused by micronized limestone hardening and agglomeration; Ash return buffer bin for storing circulating desulfurization ash; A metering system for metering fine powdered limestone and circulating desulfurization ash fed into the mixing humidification system; A mixing and humidifying system for mixing and humidifying the micropowdered limestone and circulating desulfurization ash; a water system for supplying water to the mixing humidification system; A high solid-gas ratio reactor for desulfurizing the mixed humidified material and flue gas, and the high solid-gas ratio reactor is connected with the mixed material humidification system and the flue gas pipeline; A primary separator and a dust collection system for material separation connected to the flue gas outlet of the high solid-to-gas ratio reactor, the material outlets of the primary separator and dust collection system are connected to the ash return buffer bin; And, an induced draft fan connected to the flue gas outlet of the dust collection system to provide power; It is characterized in that, comprising the steps of: Step 1: Micropowdered limestone is stored in the material buffer bin; Step 2: Design a measuring system under the material buffer silo to measure the fine powder limestone. After the metering, it enters the mixing humidification system. At the same time, the circulating desulfurization ash and humidifying water also enter the mixing humidifying system. After the mixing humidification In the system, the materials are fully mixed and humidified; The third step: the humidified mixed material is fully fluidized through the fluidization tank and then enters the high solid-gas ratio reactor; Step 4: Mix the material and flue gas components in the high solid-gas ratio reactor, and the water will change from liquid to gas under the action of hot flue gas, forming a certain wet environment on the surface of the _particles . Limestone reacts to generate desulfurization gypsum to achieve the purpose of desulfurization; Step 5: After the material reacts in the high solid-gas ratio reactor, it forms desulfurization ash and enters the primary separator together with the flue gas. The material in the primary separator is separated and enters the ash return buffer bin; part of the material enters the dust collection together with the flue gas System, after being filtered and cleaned, it is collected into the ash return buffer bin; the purified flue gas is discharged into the atmosphere through the induced draft fan; Step 6: The circulating desulfurized ash entering the ash return buffer bin is metered by the metering system under the bin and then enters the mixing humidification system, where it is mixed with desulfurizer and water, so that the process forms a cycle; Step 7: When the circulating desulfurization ash reaches the high material level in the ash return buffer bin, the desulfurization ash is discharged to form the final desulfurization ash; Wherein, the average particle size of the micropowdered limestone is less than 6µm, the moisture content of the material after humidification in the mixing humidification system is controlled at 4-6%, and the temperature of the flue gas entering the high solid-gas ratio reactor is not lower than 150°C. The temperature of the flue gas exiting the high solid-gas ratio reactor is not higher than 65°C, and the humidity is not higher than 50%. The dust concentration inside the high solid-gas ratio reactor gas is up to 3000g/Nm ³ , and the separation efficiency of the primary separator is 50~90%, and the final desulfurization ash moisture is not more than 3%. 2. A high solid-gas ratio dehumidification and desulfurization common system based on micropowdered limestone, characterized in that it includes: A material buffer bin for storing micropowdered limestone; a pneumatic activation system is set under the material buffer bin to prevent normal unloading caused by micronized limestone hardening and agglomeration; Ash return buffer bin for storing circulating desulfurization ash; A metering system for metering the fine powdered limestone and circulating desulfurized ash fed into the mixing humidification system; the metering system is an adjustable metering system, and the metering method is spiral metering or sealed belt metering; A mixing humidification system for mixing and humidifying the micronized limestone and circulating desulfurization ash; the mixing humidification system is an online mixing humidification, and the process is continuous; a water system for supplying water to the mixing humidification system; A high solid-gas ratio reactor for desulfurizing the mixed humidified material and flue gas, and the high solid-gas ratio reactor is connected with the mixed material humidification system and the flue gas pipeline; A primary separator and a dust collection system for material separation connected to the flue gas outlet of the high solid-to-gas ratio reactor, the material outlets of the primary separator and dust collection system are connected to the ash return buffer bin; An induced draft fan connected to the flue gas outlet of the dust collection system to provide power; And, a fluidization tank for fluidizing the mixed humidified material before being sent into the high solid-to-gas ratio reactor. 3. The high solid-gas ratio dehumidification and desulfurization common system based on micronized limestone according to claim 2, characterized in that the fluidization tank is pneumatic fluidization, and the material is in a suspended state after fluidization. 4. The high solid-gas ratio dehumidification and desulfurization common system based on fine powdered limestone according to claim 2, characterized in that the dust collection system is a bag filter. 5. The high solid-gas ratio dehumidification and desulfurization common system based on fine powder limestone according to claim 4, characterized in that, the bag filter is a double-filter coated bag filter.

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