CN107191956B - Flue gas purifying system - Google Patents

Abstract

The invention discloses a flue gas purification system. The flue gas purification system at least comprises a first reactor and a second reactor, and further comprises a heat exchanger, wherein an outlet of a first gas channel of the heat exchanger is communicated with a flue gas inlet of the first reactor, a flue gas discharge port of the first reactor is communicated with a flue gas inlet of the second reactor, and a flue gas discharge port of the second reactor is communicated with an inlet of a second gas channel of the heat exchanger. Thus, the high-temperature flue gas exhausted by the flue gas production equipment can be subjected to heat exchange with the low-temperature flue gas exhausted by the reactor through the heat exchanger, the temperature of the high-temperature flue gas is reduced, and the temperature of the low-temperature flue gas is increased. The flue gas purification system is utilized, equipment for heating low-temperature flue gas is not required to be arranged independently, the high-temperature flue gas is not required to be cooled by additionally arranging a cooler, the structure of the flue gas purification system can be simplified, and the equipment investment, the operation cost and the energy consumption are reduced.

Description

A flue gas purification system

Technical field

The invention relates to flue gas purification technology, and in particular to a flue gas purification system.

Background technique

Currently, flue gas production equipment such as thermal power generation and metal smelting will produce flue gas due to burning coal fuel; these flue gases contain pollutants such as SO ₂ and NOx, which have become the main source of air pollution.

At present, there are many methods for purifying flue gas. According to different principles, there are absorption method, adsorption method, catalytic conversion method, biological method and plasma method. Among them, the absorption method is the most commonly used method. Its main principle is to separate pollutants in flue gas through absorption, thereby achieving the purpose of removing pollutants such as SO ₂ and NOx.

The existing flue gas purification system using absorption method is equipped with a flue gas purification reactor. The flue gas to be purified and the appropriate absorbent are passed into the reactor. In the reactor, the absorbent contacts and reacts with the flue gas, and the flue gas is purified. The pollutants are absorbed to purify the flue gas, and then the purified flue gas is discharged or otherwise processed; the absorbed pollutants can be harmlessly treated or recycled accordingly. Chinese patent document CN 1156332C discloses a multi-phase flue gas purification reactor. The multi-phase flue gas purification reactor includes a flue gas purification reactor shell. A cone-type structure in which a cone ring and a cone are used together are installed in the shell. components to promote the mixing, contact and reaction of flue gas and absorbent.

In order to avoid the liquefaction of the moisture in the flue gas after purification, it is often necessary to heat the purified flue gas before discharge so that the moisture in the flue gas is discharged in a gaseous form; heating requires the installation of corresponding heating equipment; this setting of heating equipment This not only makes the structure of the flue gas purification system more complex and increases equipment cost, but also increases the operating cost and energy consumption of the flue gas purification system.

Contents of the invention

The purpose of the present invention is to provide a flue gas purification system that can not only reduce equipment investment, but also reduce the operating costs of the flue gas purification system and reduce the energy consumption of the flue gas purification system.

Based on the above objectives, the flue gas purification system provided by the present invention includes at least a first reactor and a second reactor, and also includes a heat exchanger. The heat exchanger at least includes a first gas channel isolated by a heat exchange medium and a second gas channel; the outlet of the first gas channel communicates with the flue gas inlet of the first reactor, and the flue gas discharge port of the first reactor communicates with the flue gas inlet of the second reactor, The flue gas discharge port of the second reactor communicates with the inlet of the second gas channel. In this way, the high-temperature flue gas discharged from the flue gas production equipment can first enter the first gas channel of the heat exchanger; at the same time, the low-temperature flue gas discharged from the flue gas discharge port of the second reactor passes through the second gas channel of the heat exchanger. , so that the high-temperature flue gas and the low-temperature flue gas can undergo heat exchange through the heat exchanger. The temperature of the high-temperature flue gas decreases and the temperature of the low-temperature flue gas rises. Therefore, using this flue gas purification system does not require separate equipment for heating low-temperature flue gas, which can simplify the structure of the flue gas purification system and reduce equipment investment and operating costs and energy consumption. In addition, lowering the temperature of high-temperature flue gas can reduce water evaporation during the purification reaction process, save water consumption, and reduce the moisture content of the flue gas after purification, which in turn helps reduce the corrosive effect of flue gas on equipment and reduces the need for defogging before flue gas discharge. .

In a further optional technical solution, the flue gas purification system further includes a smoke exhaust duct; the heat exchanger includes a heat exchange medium pipeline located in the smoke exhaust duct, and the heat exchange medium pipeline forms the third A gas channel, a second gas channel is formed outside the heat exchange medium pipeline; the flue gas discharge port of the second reactor is connected to the smoke exhaust pipe, and the flue gas discharge port of the second reactor passes through the The smoke exhaust pipe communicates with the entrance of the second gas channel. Placing the heat exchanger in the exhaust pipe can further simplify the structure of the flue gas purification system, make full use of the heat of high-temperature flue gas, and improve the comprehensive effects of energy saving, purification efficiency, etc. of the flue gas purification system.

In a further technical solution, the smoke exhaust pipe is installed on the upper part of the second reactor, and the flue gas discharge port of the second reactor communicates with the lower part of the smoke exhaust pipe. Installing the exhaust gas pipeline and the second reactor together can improve the integration of the flue gas purification system and save the space occupied by the flue gas purification system.

In a further technical solution, the upper end of the smoke exhaust pipe is connected to the atmosphere to form a chimney; this eliminates the need to build a specially constructed chimney, thereby helping to reduce the manufacturing cost of the flue gas purification system.

In a further technical solution, the flue gas inlet of the second reactor is located in the smoke exhaust pipe; it also includes an intermediate flue; one end of the intermediate flue is connected to the flue gas discharge port of the first reactor, The other end extends into the smoke exhaust pipe and is connected with the flue gas inlet of the second reactor. In this way, the exhaust pipe (chimney) can be combined with the reactor to increase the compactness of the flue gas purification system.

In a further technical solution, the flue gas discharge port of the second reactor is located at the lower part; it also includes a flue gas discharge branch pipe, the lower end of the flue gas discharge branch pipe is connected with the flue gas discharge port of the second reactor, and the upper end of the flue gas discharge branch pipe is connected with the flue gas discharge port of the second reactor. Communicated with the lower part of the smoke exhaust duct.

In a preferred technical solution, a plurality of flue gas discharge branch pipes located outside the second reactor are included, and a plurality of the flue gas discharge branch pipes are distributed around the outer periphery of the second reactor. This can ensure smooth flow of flue gas between the flue gas discharge port of the second reactor and the flue gas exhaust pipe.

In a further technical solution, a mist eliminator is provided between the flue gas discharge port of the second reactor and the second gas channel. This can reduce the moisture content of the exhaust flue gas, reduce moisture condensation during the evacuation process, and also reduce the need to heat the exhaust flue gas, which is conducive to the gaseous discharge of the moisture in the flue gas.

In a further technical solution, a mist eliminator is provided between the flue gas discharge port of the second reactor and the lower end of the flue gas discharge branch pipe. Demisting at the front end close to the flue gas flow can reduce the adverse impact of moisture in the flue gas on back-end equipment (such as heat exchangers).

In an optional technical solution, the heat exchanger further includes a third channel, and the third channel is isolated from the first gas channel and the second gas channel by a thermal exchange medium. In this way, when the simple heat exchange between high-temperature flue gas and low-temperature flue gas cannot meet the needs of flue gas purification, the flue gas temperature can be adjusted through the third channel. When the heat output of high-temperature flue gas cannot meet the needs of low-temperature flue gas heating, the flue gas temperature can be adjusted through the third channel. A higher temperature fluid (liquid or gas) is input through the third channel to meet the heating needs of low-temperature flue gas; conversely, a lower-temperature fluid can be input through the third channel to meet the need to reduce high-temperature flue gas.

Description of drawings

Figure 1 is a schematic structural diagram of a flue gas purification system provided by an embodiment of the present invention.

Figure 2 is a schematic structural diagram of the A-A section in Figure 1.

Figure 3 is a schematic diagram of flue gas flow according to another embodiment of the present invention.

Detailed ways

In the known technology, the temperature of the flue gas to be purified discharged from the flue gas production equipment is relatively high. Before the flue gas to be purified (high temperature flue gas) enters the flue gas purification system, a corresponding cooler needs to be set up to cool the flue gas to be purified to avoid The temperature in the reactor is too high. In view of the shortcomings of the background technology, one of the cores of the present invention is to transfer the thermal energy in the high-temperature flue gas to the purified flue gas (low-temperature flue gas) to achieve the purpose of heating the low-temperature flue gas and at the same time achieve the effect of reducing the high-temperature flue gas. . The following describes specific embodiments of the flue gas purification system provided by the present invention. The flue gas purification system can be used for desulfurization and/or denitrification or removal of other pollutants from flue gas.

Please refer to Figures 1 and 2. Figure 1 is a schematic structural diagram of a flue gas purification system provided by an embodiment of the present invention. Figure 2 is a schematic structural diagram of the A-A cross-section in Figure 1. The flue gas purification system provided by the embodiment of the present invention includes at least two reactors, called the first reactor 100 and the second reactor 200. The first reactor 100 and the second reactor 200 are configured in series, that is, the first reactor 100 and the second reactor 200. The flue gas discharge port 102 of the first reactor 100 and the flue gas inlet 201 of the second reactor 200 are connected through the intermediate flue 500, so that the flue gas discharged from the first reactor 100 can enter the second reactor 200. The flue gas is purified at least twice.

In this embodiment, both the first reactor 100 and the second reactor 200 may be provided with a cone-type structural member using a cone ring and a cone body according to known technology. The flue gas inlet 101 of the first reactor 100 and the flue gas inlet 201 of the second reactor 200 are both located at the upper part, and the flue gas discharge port 102 of the first reactor 100 and the flue gas discharge port 202 of the second reactor 200 are both located at the upper part. lower part.

Those skilled in the art can understand that the first reactor 100 and the second reactor 200 can be used to purify the same pollutant, such as desulfurization, or they can also be used to purify different pollutants, such as the first reactor 100 is mainly used to purify different pollutants. It is used to remove sulfur (such as SO ₂ ) in the flue gas. The second reactor 200 is mainly used to remove (a small amount of SO ₂ ), nitrate, dust, water vapor, etc. (such as NOx) in the flue gas. Of course, according to actual needs, three or four reactors connected in series can be set up, and different reactors can have different or the same main functions; of course, the specific structure and working mode of the reactor can also be set according to actual needs.

In addition, the flue gas purification system provided by the embodiment of the present invention also includes a heat exchanger 300. The heat exchanger 300 at least includes a first gas channel and a second gas channel isolated by a heat exchange medium; the outlet of the first gas channel is connected to the first gas channel. The flue gas inlet of the reactor 100 is in communication, and the flue gas discharge port 202 of the second reactor 200 is in communication with the inlet of the second gas channel.

Utilizing this flue gas purification system, the high-temperature flue gas (temperature range is roughly 150-160 degrees) discharged from the flue gas production equipment (boiler, metallurgical furnace or other equipment) can be communicated with the first gas channel inlet of the heat exchanger 300 ( Directly connected or indirectly connected), so that the high-temperature flue gas enters the first gas channel of the heat exchanger 300 first. At the same time, the low-temperature flue gas (temperature range is approximately about 50 degrees) discharged from the flue gas discharge port 202 of the second reactor 200 passes through the second gas channel of the heat exchanger 300 . In this way, the heat exchanger 300 can perform heat exchange between high-temperature flue gas and low-temperature flue gas, so that the temperature of the high-temperature flue gas decreases and the temperature of the low-temperature flue gas increases. Reducing the temperature of high-temperature flue gas can reduce water evaporation during the purification reaction process, save water consumption, and reduce the moisture content of the flue gas after purification, which in turn helps reduce the corrosive effect of flue gas on equipment and reduces the need for defogging before flue gas emission.

Compared with the existing technology that specially sets up heating equipment to heat purified low-temperature flue gas, this flue gas purification system does not need to separately set up equipment for heating low-temperature flue gas; in addition, since the temperature of high-temperature flue gas can be reduced at the same time, thus There is no need to install a cooler to cool the high-temperature flue gas, which can simplify the structure of the flue gas purification system and reduce equipment investment, operating costs and energy consumption.

Please refer to Figure 1 again. In this embodiment, the flue gas purification system also includes a smoke exhaust pipe 400 located above the second reactor. The lower end of the smoke exhaust pipe 400 is connected to the second reactor 200, and the upper end extends upward. An exhaust pipe 400 is formed inside. Smoke cavity.

The heat exchanger 300 can be formed in the smoke exhaust duct, specifically including the heat exchange medium pipeline located in the smoke exhaust duct 400 . The heat exchange medium pipeline extends laterally in the smoke exhaust pipe 400, and a first gas channel is formed inside. A second gas channel is formed outside the heat exchange medium pipeline. Of course, in order to improve the heat exchange efficiency, the heat exchange medium pipeline can be arranged in a spiral, U-shaped or other shape. In order to guide the flow direction of gas outside the heat exchange medium pipeline, the heat exchange medium pipeline can be provided with a predetermined shape to increase the flow path of the low-temperature flue gas, increase the time for passing through the heat exchanger 300, and improve the heat exchange efficiency.

As shown in Figures 1 and 2, since the flue gas discharge port 202 of the second reactor 200 is located at the lower part, a plurality of flue gas discharge branch pipes 600 are provided around the second reactor 200, so that the lower ends of the flue gas discharge branch pipes 600 are in contact with each other. The flue gas discharge port 202 of the second reactor 200 is communicated with the upper end of the second reactor 200 and the lower part of the flue gas exhaust pipe 400 . In this way, the flue gas (low-temperature flue gas) discharged from the lower part of the second reactor 200 can be introduced into the lower part of the flue gas exhaust pipe 400 through the flue gas discharge branch pipe 600, and then reaches the heat exchanger of the heat exchanger 300 through the flue gas exhaust pipe 400. The outside of the medium pipeline (the second gas channel) then conducts heat exchange with the high-temperature flue gas in the first gas channel inside the heat exchange medium pipeline.

Providing multiple flue gas discharge branch pipes 600 outside the second reactor 200 can ensure smooth flow of flue gas between the flue gas discharge port of the second reactor 200 and the flue gas exhaust pipe 400 .

Since the flue gas inlet 201 of the second reactor 200 is located in the smoke exhaust duct 400; in this embodiment, the smoke exhaust duct 400 is provided with corresponding holes so that one end of the intermediate flue 500 extends into the smoke exhaust duct 400 and connects with the second The flue gas inlets 201 of the reactor 200 are connected. In this way, the smoke exhaust pipe 400 (chimney) can be combined with the reactor, thereby increasing the compactness of the flue gas purification system. Of course, heat exchange can also be performed between the low-temperature flue gas entering the flue gas duct 400 through the flue gas discharge branch pipe 600 and the flue gas in the intermediate flue 500, so as to reduce the temperature of the flue gas entering the second reactor 200 and increase the temperature of the flue gas entering the exhaust pipe 400. The temperature of the flue gas in the flue pipe 400 is conducive to improving the comprehensive effect of flue gas treatment in the flue gas purification system.

In this embodiment, the heat exchanger 300 is arranged in the smoke exhaust pipe 400, which can further simplify the structure of the flue gas purification system, make full use of the heat in the high-temperature flue gas, and improve the energy saving and purification efficiency of the flue gas purification system. Comprehensive effect. In addition, in this embodiment, installing the flue gas pipeline 400 and the second reactor 200 together can improve the integration of the flue gas purification system and save the space occupied by the flue gas purification system.

Of course, the upper end of the smoke exhaust pipe 400 can be connected to the atmosphere to form a chimney; this eliminates the need for a specially built chimney, thereby helping to reduce the manufacturing cost of the flue gas purification system. It can be understood that, according to the specific structure of the second reactor 200, those skilled in the art can configure appropriate pipes to guide the flow of flue gas to achieve the purpose of the present invention.

In order to reduce the moisture content of the exhaust flue gas (eg, exhaust flue gas), a mist eliminator may be provided between the flue gas discharge port 202 of the second reactor 200 and the second gas channel. In order to reduce the possibility of condensation during the evacuation of moisture, it is beneficial to discharge the moisture in the flue gas in the gaseous state. In this embodiment, a demister 700 is provided between the flue gas discharge port 202 of the second reactor 200 and the lower end of the flue gas discharge branch pipe 600 . In this way, defogging at the front end close to the flue gas flow can reduce the adverse effects of moisture in the flue gas on the corrosion of back-end equipment (such as heat exchangers).

Those skilled in the art can understand that the reactor and heat exchanger 300 can be appropriately arranged according to different reactor structures, as shown in Figure 3, which shows a schematic diagram of the flue gas flow direction according to another embodiment of the present invention. In this embodiment, the flue gas inlet of the first reactor 100 is located at the upper part, and the flue gas discharge port is located at the lower part; the flue gas inlet of the second reactor 200 is located at the lower part, and the flue gas discharge port is located at the upper part. In this flue gas purification system, the flue gas flow path is: the first gas channel of the heat exchanger 300 → the first reactor 100 → the second reactor 100 → the second gas channel of the heat exchanger 300. High-temperature flue gas and low-temperature flue gas undergo heat exchange in the heat exchanger 300 . Of course, in the actual construction of a flue gas purification system, flue gas pipes of appropriate length and effective cross-section can be set up as needed to guide the flow of flue gas.

Considering that the input amount of high-temperature flue gas and the discharge amount of low-temperature flue gas are limited by the processing capacity of the flue gas purification system, in order not to affect the processing capacity of the flue gas purification system, the heat exchanger 300 also includes a third channel, and the third channel is connected with the first The gas channel and the second gas channel can be isolated by a thermal communication medium, and the third channel can be a liquid channel or a gas channel. In this way, when the simple heat exchange between high-temperature flue gas and low-temperature flue gas cannot meet the needs of flue gas purification, the temperature of low-temperature or high-temperature flue gas can be adjusted through the third channel. When the heat output of high-temperature flue gas cannot meet the needs of low-temperature flue gas heating, When needed, a higher temperature fluid (liquid or gas) can be input through the third channel to meet the heating needs of low-temperature flue gas; conversely, a lower-temperature fluid can be input through the third channel to meet the need to reduce high-temperature flue gas. needs; this can increase the adaptability of the flue gas purification system. According to actual needs, the heat exchanger 300 can be configured as a gas-gas heat exchanger or a liquid-gas heat exchanger.

The above description is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered. regarded as the protection scope of the present invention.

Claims (6)

1. A flue gas cleaning system comprising at least a first reactor (100) and a second reactor (200), characterized by further comprising a heat exchanger (300), the heat exchanger (300) comprising at least a first gas channel and a second gas channel separated by a heat exchange medium;

the outlet of the first gas channel is communicated with the flue gas inlet of the first reactor (100), the flue gas discharge port (102) of the first reactor (100) is communicated with the flue gas inlet (201) of the second reactor (200), and the flue gas discharge port (202) of the second reactor (200) is communicated with the inlet of the second gas channel;

also comprises a smoke exhaust pipe (400); the heat exchanger (300) comprises a heat exchange medium pipeline positioned in the smoke exhaust pipeline (400), wherein the first gas channel is formed in the heat exchange medium pipeline, and a second gas channel is formed outside the heat exchange medium pipeline; the fume exhaust port (202) of the second reactor (200) is communicated with the inlet of the second gas channel through the fume exhaust pipeline (400);

the smoke exhaust pipeline (400) is arranged at the upper part of the second reactor (200), and the smoke exhaust port (202) of the second reactor (200) is communicated with the lower part of the smoke exhaust pipeline (400);

-the flue gas inlet (201) of the second reactor (200) is located in the flue gas duct (400);

also comprises an intermediate flue (500); one end of the middle flue (500) is connected with the smoke discharge port (102) of the first reactor (100), and the other end of the middle flue extends into the smoke discharge pipeline (400) to be connected with the smoke inlet (201) of the second reactor (200);

the fume discharge port (202) of the second reactor (200) is positioned at the lower part; the device also comprises a smoke discharge branch pipe (600), wherein the lower end of the smoke discharge branch pipe (600) is communicated with the smoke discharge port (202) of the second reactor (200), and the upper end of the smoke discharge branch pipe is communicated with the lower part of the smoke discharge pipeline (400).

2. The flue gas cleaning system according to claim 1, wherein the upper end of the flue gas exhaust duct (400) is vented to atmosphere to form a stack.

3. The flue gas cleaning system according to claim 1, comprising a plurality of flue gas discharge branches (600) located outside the second reactor (200), a plurality of said flue gas discharge branches (600) being distributed at the periphery of said second reactor (200).

4. A flue gas cleaning system according to claim 1, characterized in that a mist eliminator (700) is arranged between the flue gas discharge (202) of the second reactor (200) and the second gas channel.

5. A flue gas cleaning system according to claim 4, wherein a mist eliminator (700) is arranged between the flue gas discharge opening (202) of the second reactor (200) and the lower end of the flue gas discharge branch pipe (600).

6. A flue gas cleaning system according to any one of claims 1-5, wherein the heat exchanger (300) further comprises a third channel, which is isolated from both the first gas channel and the second gas channel by a heat exchange medium.