Flue gas de-whitening method and device

Abstract

The present invention provides a flue gas desaturation method and device, comprising the following steps: heat exchange treatment of the saturated wet flue gas after desulfurization through a flue gas heat exchanger, so that the temperature of the saturated wet flue gas after desulfurization is reduced to precipitate condensed water, and obtain flue gas with reduced moisture content; the flue gas with reduced moisture content is passed into the tail gas chimney, and the flue gas with reduced moisture content is heated by passing a heat source gas into the tail gas chimney to obtain a mixed flue gas; the temperature of the mixed flue gas is made greater than the standard saturation temperature of the mixed flue gas to ensure that the mixed flue gas is an unsaturated mixed flue gas; the unsaturated mixed flue gas is discharged from the exhaust port of the tail gas chimney. The present invention can solve the problems of the existing desaturation technology, such as high requirements on equipment materials, high system investment costs, corrosion, blockage, leakage and other phenomena after the system is put into operation, which limits the actual application.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and more specifically, to a flue gas de-whitening method and device. Background Art

[0002] After wet desulfurization, the water content in the flue gas is basically saturated. When the flue gas is discharged into the atmosphere through the chimney, the outside temperature drops, and some of the vapor water and pollutants in the flue gas condense, forming misty water vapor at the chimney outlet, producing white smoke plumes, causing serious visual pollution, causing great concerns for surrounding residents, and bringing certain pressure to the factory's environmental protection work. In addition, the condensate in the white smoke plume is weakly acidic, which will corrode nearby buildings and steel structures after floating down, and will also cause certain harm to the growth of plants.

[0003] The existing white smoke elimination technologies mainly include MGGH technology, GGH technology and direct dehumidification technology. Among them, the principle of MGGH technology is to use the heat in the high-temperature flue gas before desulfurization to heat the heat medium, and at the same time, the heat medium transfers the heat to the low-temperature flue gas after desulfurization. The heat medium circulates between the high-temperature flue gas and the low-temperature flue gas, and continuously transfers the heat in the high-temperature flue gas to the low-temperature flue gas. The increase in the temperature of the low-temperature flue gas can eliminate white smoke. The disadvantage of this technology is that it will produce a certain degree of corrosiveness, and the equipment material requirements are high, and the investment is high; GGH technology uses the high-temperature flue gas at the inlet of the desulfurization system to heat the low-temperature flue gas after desulfurization. The two flue gases are directly in indirect contact in the GGH to achieve heat exchange. The low-temperature flue gas after desulfurization is heated and then discharged into the atmosphere through the chimney to eliminate white smoke. However, the investment and operating costs of this technology are high, and there are problems such as corrosion, blockage and leakage, so its use is subject to certain restrictions. For direct dehumidification technology, if the white smoke plume is completely eliminated, the operating cost and investment cost are high, so some projects directly dehumidify after the desulfurization tower. This method has low investment and operating costs, but it cannot completely eliminate white smoke, and white smoke can still be seen when the atmospheric temperature is low.

[0004] In summary, the existing de-whitening technology has high requirements on equipment materials, which makes the system investment cost high. In addition, after the system is put into operation, there are problems such as corrosion, blockage, and leakage, which are subject to certain limitations in practical applications. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a flue gas de-whitening method and device to solve the problems of the current existing de-whitening technology, which has high requirements on equipment materials, resulting in high system investment costs, and corrosion, blockage, leakage and other phenomena after the system is put into operation, which limits its practical application.

[0006] The present invention provides a flue gas deoxidation method, which is characterized by comprising the following steps:

[0007] The saturated wet flue gas after desulfurization is subjected to heat exchange treatment by a flue gas heat exchanger, so that the temperature of the saturated wet flue gas after desulfurization is reduced to precipitate condensed water, thereby obtaining flue gas with reduced moisture content;

[0008] Passing the flue gas with reduced moisture content into a tail gas chimney, and heating the flue gas with reduced moisture content by passing a heat source gas into the tail gas chimney to obtain a mixed flue gas;

[0009] The temperature of the mixed flue gas is made greater than the standard saturation temperature of the mixed flue gas, so as to ensure that the mixed flue gas is unsaturated mixed flue gas;

[0010] The unsaturated mixed flue gas is discharged from the exhaust outlet of the tail gas chimney.

[0011] In addition, a preferred solution is that the heat exchange treatment of the desulfurized saturated wet flue gas by a flue gas heat exchanger to reduce the temperature of the desulfurized saturated wet flue gas and precipitate condensed water to obtain flue gas with reduced moisture content comprises:

[0012] Introducing the desulfurized saturated wet flue gas and air into the flue gas heat exchanger respectively;

[0013] The flue gas heat exchanger performs heat exchange treatment on the desulfurized saturated wet flue gas and the air, so that the temperature of the desulfurized saturated wet flue gas is reduced, condensed water is precipitated, and flue gas with reduced moisture content is obtained.

[0014] In addition, a preferred solution is that in the process of respectively introducing the desulfurized saturated wet flue gas and air into the flue gas heat exchanger,

[0015] Introducing the desulfurized saturated wet flue gas into the heat source inlet of the flue gas heat exchanger through a flue gas duct; and / or,

[0016] Air is introduced into the cold source inlet of the flue gas heat exchanger through a fan.

[0017] In addition, a preferred solution is to pass the flue gas with reduced moisture content into a tail gas chimney, and to increase the temperature of the flue gas with reduced moisture content by passing a heat source gas into the tail gas chimney, so as to obtain a mixed flue gas comprising:

[0018] Passing the flue gas with reduced moisture content into an exhaust chimney;

[0019] The heated air obtained after the heat exchange treatment is introduced into the tail gas chimney as a heat source gas to be mixed with the flue gas with reduced moisture content in the tail gas chimney, so that the flue gas with reduced moisture content is heated to obtain mixed flue gas.

[0020] In addition, a preferred solution is that in the process of introducing the heated air obtained after the heat exchange treatment as a heat source gas into the tail gas chimney and mixing it with the flue gas with reduced moisture content in the tail gas chimney to heat the flue gas with reduced moisture content to obtain the mixed flue gas,

[0021] The heated air is introduced into the exhaust chimney through the air duct; wherein,

[0022] The heated air enters the tail gas chimney from the rear end of the tail gas chimney;

[0023] The flue gas with reduced moisture content enters the tail gas chimney from the middle of the tail gas chimney.

[0024] In addition, a preferred solution is that the flue gas heat exchanger is a plate heat exchanger.

[0025] In addition, a preferred solution is that after the desulfurized saturated wet flue gas is subjected to heat exchange treatment by the flue gas heat exchanger to reduce the temperature of the desulfurized saturated wet flue gas to precipitate condensed water and obtain flue gas with reduced moisture content, the method further comprises:

[0026] The condensed water precipitated from the saturated wet flue gas after desulfurization during the heat exchange process is recycled.

[0027] The present invention provides a flue gas decolorization device for the flue gas decolorization method as described above, comprising a flue gas heat exchanger, a cold source introduction device and a hot source gas introduction device; wherein:

[0028] The flue gas heat exchanger comprises a heat source inlet and a cold source inlet;

[0029] The desulfurized saturated wet flue gas pipeline is connected to the heat source inlet, and the cold source introduction device is connected to the cold source inlet;

[0030] The flue gas outlet after heat exchange with the cold source of the flue gas heat exchanger is connected to the tail gas chimney through the tail gas pipeline, and the heat source gas introduction device is connected to the tail gas chimney.

[0031] From the above technical scheme, it can be seen that the method and device for eliminating white smoke provided by the present invention performs heat exchange treatment on the saturated wet smoke after desulfurization through a flue gas heat exchanger, so that the temperature of the saturated wet smoke after desulfurization is reduced to precipitate condensed water, which greatly reduces the moisture content (or relative humidity) of the exhaust smoke, thereby reducing the dew point temperature of the exhaust smoke, so that the exhaust smoke does not reach the dew point temperature in a short time after being discharged, and the moisture in the tail gas will not condense into water mist, thereby achieving the purpose of reducing white smoke. The present invention can effectively eliminate white smoke, reduce equipment corrosion, extend system life, effectively solve the blockage problem, and has the advantages of low investment and low energy consumption.

[0032] In order to achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more clear and easy to understand. In the accompanying drawings:

[0034] Figure 1 is a flow chart of a flue gas whitening method according to an embodiment of the present invention;

[0035] Figure 2 Schematic diagram of the structure of the flue gas whitening device according to an embodiment of the present invention

[0036] In the attached drawings, 1-flue gas heat exchanger, 2-exhaust gas chimney, 3-flue gas duct, 4-fan, 5-air duct, 6-exhaust gas duct, 7-saturated wet flue gas duct after desulfurization.

[0037] The same reference numerals throughout the drawings indicate similar or corresponding features or functions. DETAILED DESCRIPTION

[0038] In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. However, it is apparent that these embodiments may also be implemented without these specific details.

[0039] In view of the above-mentioned existing flue gas dewhitening technology, which has high requirements on equipment materials, resulting in high system investment costs, and corrosion, blockage, leakage and other phenomena after the system is put into operation, which limits its practical application. A flue gas dewhitening method and device are proposed.

[0040] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] In order to illustrate the flue gas deoxidation method provided by the present invention, Figure 1 The flow chart of the flue gas whitening method according to an embodiment of the present invention is shown; Figure 2 The structure of a flue gas whitening device according to an embodiment of the present invention is shown.

[0042] like Figure 1 Knot and Figure 2 As shown in the figure, the flue gas deoxidation method provided by the present invention comprises the following steps:

[0043] S1, performing heat exchange treatment on the saturated wet flue gas after desulfurization through a flue gas heat exchanger 1, so that the temperature of the saturated wet flue gas after desulfurization is reduced to precipitate condensed water, thereby obtaining flue gas with reduced moisture content;

[0044] S2, passing the flue gas with reduced moisture content into the tail gas chimney 2, and heating the flue gas with reduced moisture content by passing heat source gas into the tail gas chimney 2 to obtain mixed flue gas;

[0045] S3, making the temperature of the mixed flue gas greater than the standard saturation temperature of the mixed flue gas, ensuring that the mixed flue gas is unsaturated mixed flue gas;

[0046] S4. Discharge the unsaturated mixed flue gas from the exhaust outlet of the tail gas chimney 2.

[0047] The saturated wet flue gas after desulfurization is heat exchanged by the flue gas heat exchanger 1, so that the temperature of the saturated wet flue gas after desulfurization is reduced to precipitate condensed water, which greatly reduces the moisture content (or relative humidity) of the exhaust flue gas, thereby reducing the dew point temperature of the exhaust flue gas, so that the exhaust flue gas does not reach the dew point temperature in a short time after being discharged, and the moisture in the tail gas will not condense into water mist, thereby achieving the purpose of reducing white smoke. The present invention can effectively eliminate white smoke, reduce equipment corrosion, extend system life, effectively solve the blockage problem, and has the advantages of low investment and low energy consumption.

[0048] As a preferred embodiment of the present invention, the saturated wet flue gas after desulfurization is subjected to heat exchange treatment by the flue gas heat exchanger 1, so that the temperature of the saturated wet flue gas after desulfurization is reduced to precipitate condensed water, and the flue gas with reduced moisture content is obtained, which includes:

[0049] The saturated wet flue gas after desulfurization and air are introduced into the flue gas heat exchanger 1 respectively;

[0050] The saturated wet flue gas after desulfurization and air are heat exchanged by the flue gas heat exchanger 1, so that the temperature of the saturated wet flue gas after desulfurization is reduced, and condensed water is precipitated to obtain flue gas with reduced moisture content.

[0051] The saturated wet flue gas after desulfurization in the flue gas heat exchanger 1 is heat exchanged by introducing air, and the air obtained after the heat exchange can be discharged or used as a subsequent heat source gas, wherein the air can also be replaced by circulating water to reduce the temperature of the saturated wet flue gas after desulfurization.

[0052] As a preferred embodiment of the present invention, in the process of introducing the desulfurized saturated wet flue gas and air into the flue gas heat exchanger 1 respectively, the desulfurized saturated wet flue gas is introduced into the heat source inlet of the flue gas heat exchanger 1 through the flue gas duct 3; and / or, the air is introduced into the cold source inlet of the flue gas heat exchanger 1 through the fan 4. The flue gas duct 3 and the fan 4 are helpful to introduce the flue gas and air into the flue gas heat exchanger 1 for heat exchange, wherein the average temperature of the air at the outlet of the fan 4 is 15°C.

[0053] As a preferred embodiment of the present invention, the flue gas with reduced moisture content is introduced into the tail gas chimney 2, and the flue gas with reduced moisture content is heated by introducing a heat source gas into the tail gas chimney 2 to obtain a mixed flue gas including:

[0054] Passing the flue gas with reduced moisture content into the tail gas chimney 2;

[0055] The heated air obtained after the heat exchange treatment is introduced into the tail gas chimney 2 as the heat source gas and mixed with the flue gas with reduced moisture content in the tail gas chimney 2, so that the flue gas with reduced moisture content is heated to obtain mixed flue gas. The heated air is used as the heat source gas to achieve the effect of waste heat utilization, and other waste heat flue gas or waste heat steam can also be used as the heat source gas to utilize waste heat.

[0056] As a preferred embodiment of the present invention, the heated air obtained after the heat exchange treatment is introduced into the tail gas chimney 2 as the heat source gas to be mixed with the flue gas with reduced moisture content in the tail gas chimney 2, so that the flue gas with reduced moisture content is heated to obtain the mixed flue gas.

[0057] The heated air is introduced into the exhaust chimney 2 through the air duct 5; wherein,

[0058] The heated air enters the tail gas chimney 2 from the rear end of the tail gas chimney 2;

[0059] The flue gas with reduced moisture content enters the tail gas chimney 2 from the middle of the tail gas chimney 2 .

[0060] It is convenient for the flue gas with reduced moisture content to be fully mixed with the heated air, so that the temperature of the flue gas with reduced moisture content can be raised more evenly.

[0061] As a preferred embodiment of the present invention, the flue gas heat exchanger 1 is a plate heat exchanger, which has a better heat exchange effect.

[0062] As a preferred embodiment of the present invention, after the saturated wet flue gas after desulfurization is subjected to heat exchange treatment by a flue gas heat exchanger to reduce the temperature of the saturated wet flue gas after desulfurization to precipitate condensed water and obtain flue gas with reduced moisture content, the method further comprises:

[0063] The condensed water generated during the heat exchange process of the saturated wet flue gas after desulfurization is recycled and reused. The collected condensed water can be reused in the system.

[0064] The flue gas decolorization device provided by the present invention for the flue gas decolorization method as described above comprises a flue gas heat exchanger 1, a cold source introduction device and a hot source gas introduction device; wherein,

[0065] The flue gas heat exchanger 1 includes a heat source inlet and a cold source inlet;

[0066] The saturated wet flue gas pipeline 7 after desulfurization is connected to the heat source inlet, and the cold source introduction device is connected to the cold source inlet;

[0067] The flue gas outlet after heat exchange with the cold source of the flue gas heat exchanger 1 is connected to the tail gas chimney 2 through the tail gas pipeline 6, and the heat source gas introduction device is connected to the tail gas chimney 2.

[0068] As a preferred embodiment of the present invention, the cold source introduction device is a fan 4; the heat source gas introduction device is an air duct 5; and the air duct 5 is connected to the hot gas outlet after heat exchange with the heat source of the flue gas heat exchanger 1.

[0069] In order to better illustrate the smoke whitening method and device provided by the present invention, specific embodiments are provided as follows:

[0070] After desulfurization, the flue gas is 42℃ saturated wet flue gas (water content 8.1%), and the flue gas flow rate is 238846Nm 3 / h, enters the flue gas heat exchanger, exchanges heat with the blown air and cools down to 37℃ (water content 6.2%), and the flue gas flow rate becomes 234008Nm 3 / h.

[0071] The average temperature of the fan outlet air is 15°C, and the flow rate is 300000Nm 3 / h, after heat exchange with the flue gas after desulfurization, the temperature rises to 39.3℃, and the flow rate remains unchanged.

[0072] The desulfurized flue gas after cooling is mixed with the heated air in the chimney. The flue gas temperature is 38.3℃ (water content 3.2%) and the flow rate is 534008Nm 3 / h, 13℃ higher than the saturation temperature. At this time, the mixed flue gas is in an unsaturated state, and no condensed water mist or white smoke will be generated during discharge.

[0073] It can be seen from the above specific embodiments that the flue gas whitening method and device provided by the present invention performs heat exchange treatment on the saturated wet flue gas after desulfurization through a flue gas heat exchanger, so that the temperature of the saturated wet flue gas after desulfurization is reduced to precipitate condensed water, greatly reducing the moisture content (or relative humidity) of the exhaust flue gas, thereby reducing the dew point temperature of the exhaust flue gas, so that the exhaust flue gas does not reach the dew point temperature in a short time after being discharged, and the moisture in the tail gas will not condense into water mist, thereby achieving the purpose of reducing white smoke. The present invention can effectively eliminate white smoke, reduce equipment corrosion, extend system life, effectively solve the blockage problem, and has the advantages of low investment and low energy consumption.

[0074] As described above, the flue gas deoxidation method and device proposed in the present invention are described by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various improvements can be made to the flue gas deoxidation method and device proposed in the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the attached claims.

Claims

1. A method for eliminating flue gas whiteness, characterized in that: The steps include: The saturated wet flue gas after desulfurization is subjected to heat exchange treatment by a flue gas heat exchanger, so that the temperature of the saturated wet flue gas after desulfurization is reduced to precipitate condensed water, thereby obtaining flue gas with reduced moisture content; The flue gas with reduced moisture content is passed into a tail gas chimney, and a heat source gas is passed into the tail gas chimney to heat the flue gas with reduced moisture content to obtain a mixed flue gas, including: passing the flue gas with reduced moisture content into the tail gas chimney; passing the heated air obtained after the heat exchange treatment into the tail gas chimney as a heat source gas to mix with the flue gas with reduced moisture content in the tail gas chimney, so as to heat the flue gas with reduced moisture content to obtain a mixed flue gas; wherein, in the process of passing the heated air obtained after the heat exchange treatment into the tail gas chimney as a heat source gas to mix with the flue gas with reduced moisture content in the tail gas chimney, so as to heat the flue gas with reduced moisture content to obtain a mixed flue gas, the heated air is introduced into the tail gas chimney through an air duct; the heated air enters the tail gas chimney from the tail end of the tail gas chimney; the flue gas with reduced moisture content enters the tail gas chimney from the middle of the tail gas chimney through the tail gas pipe; The temperature of the mixed flue gas is made greater than the standard saturation temperature of the mixed flue gas, so as to ensure that the mixed flue gas is unsaturated mixed flue gas; The unsaturated mixed flue gas is discharged from the exhaust outlet of the tail gas chimney.

2. The flue gas deoxidation method according to claim 1, characterized in that: The step of performing heat exchange treatment on the desulfurized saturated wet flue gas through a flue gas heat exchanger to reduce the temperature of the desulfurized saturated wet flue gas and precipitate condensed water to obtain flue gas with reduced moisture content comprises: Introducing the desulfurized saturated wet flue gas and air into the flue gas heat exchanger respectively; The flue gas heat exchanger performs heat exchange treatment on the desulfurized saturated wet flue gas and the air, so that the temperature of the desulfurized saturated wet flue gas is reduced, condensed water is precipitated, and flue gas with reduced moisture content is obtained.

3. The flue gas deoxidation method according to claim 2, characterized in that: In the process of respectively introducing the desulfurized saturated wet flue gas and air into the flue gas heat exchanger, Introducing the desulfurized saturated wet flue gas into the heat source inlet of the flue gas heat exchanger through a flue gas duct; and / or, Air is introduced into the cold source inlet of the flue gas heat exchanger through a fan.

4. The flue gas deoxidation method according to claim 1, characterized in that: The flue gas heat exchanger is a plate heat exchanger.

5. The flue gas deoxidation method according to claim 1, characterized in that: After the desulfurized saturated wet flue gas is heat exchanged by the flue gas heat exchanger to reduce the temperature of the desulfurized saturated wet flue gas to precipitate condensed water and obtain flue gas with reduced moisture content, the method further includes: The condensed water precipitated from the saturated wet flue gas after desulfurization during the heat exchange process is recycled.

6. A flue gas decolorization device used in the flue gas decolorization method according to any one of claims 1 to 5, characterized in that: It includes a flue gas heat exchanger, a cold source introduction device and a hot source gas introduction device; wherein, The flue gas heat exchanger comprises a heat source inlet and a cold source inlet; The desulfurized saturated wet flue gas pipeline is connected to the heat source inlet, and the cold source introduction device is connected to the cold source inlet; The flue gas outlet after heat exchange with the cold source of the flue gas heat exchanger is connected to the tail gas chimney through the tail gas pipeline, and the heat source gas introduction device is connected to the tail gas chimney through the heat source gas pipeline; wherein, The cold source introduction device is a fan; the heat source gas introduction device is an air duct; the air duct is connected to the hot gas outlet after heat exchange with the heat source of the flue gas heat exchanger; The heated air is introduced into the tail gas chimney through the air duct; the heated air enters the tail gas chimney from the tail end of the tail gas chimney; the flue gas with reduced moisture content enters the tail gas chimney from the middle of the tail gas chimney through the tail gas pipeline.

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