An apparatus and method for collecting ammonium bisulfate in flue gas of a coal-fired power station

Abstract

An apparatus and method for collecting ammonium bisulfate in the flue gas of a coal-fired power plant. The apparatus includes a flue gas collection pipeline, a hot air pipe bundle, a flue gas discharge pipeline, as well as a flushing and collection loop and a temperature feedback control system. The input end of the hot air pipe bundle is connected to the flue gas collection pipeline through a gas distributor, and the output end is connected to the input end of an expander. The gas outlet of the expander is connected to the flue gas discharge pipeline. The flushing and collection loop includes an absorption liquid tank. The output end of the absorption liquid tank is connected in parallel with the flue gas collection pipeline at the input end of the hot air pipe bundle, and the input end of the absorption liquid tank is connected to the liquid outlet of the expander. The temperature feedback control system includes a fan controller, a temperature sensor arranged in the hot air pipe bundle, a variable-frequency fan and an electric heating pipe arranged successively on one side of the hot air pipe bundle. The input end of the fan controller is connected to the temperature sensor, and the output end is respectively connected to the variable-frequency fan and the electric heating pipe. The invention has a simple structure, convenient operation, high system stability, and realizes accurate and efficient operation of ammonium bisulfate sampling.

Description

Technical Field

[0001] The invention relates to the field of ammonium bisulfate sampling, and in particular to a device and method for collecting ammonium bisulfate in flue gas from a coal-fired power station. Background Art

[0002] In 2014-2015, national policy programs such as the "Action Plan for Upgrading and Renovating Coal-fired Power Plants for Energy Conservation and Emission Reduction (2014-2020)" and the "Work Plan for Comprehensively Implementing Ultra-low Emission and Energy Conservation Renovation of Coal-fired Power Plants" were successively introduced, pushing my country's coal-fired power unit pollution emission standards to a new level. In some key areas, SO2 and other emission indicators far exceeded European and American standards, becoming the "strictest in the world". SO2 and NO x The emission concentration must be controlled at 35mg / m 3 and 50 mg / m 3 Below, most power plants have already retrofitted their environmental protection equipment in accordance with ultra-low emission standards.

[0003] SCR denitrification, short for Selective Catalytic Reduction (SCR), is a widely used denitrification technology in ultra-low emission retrofits. Due to its high removal efficiency and stable operation, it has become a prevalent denitrification technology in coal-fired power plants. Common SCR denitrification units utilize a low-dust layout. However, in actual power plant operation, limitations in the denitrification flow field and ammonia injection control result in a certain amount of ammonia slipping from the denitrification outlet. This ammonia reacts with SO₂ and H₂O in the flue gas to form viscous ammonium bisulfate, which causes significant ash accumulation and increased resistance on the flue gas side of the downstream air preheater, compromising stable operation and posing a significant risk. Furthermore, in the research on the SO₂ tolerance of low- and medium-load denitrification catalysts, researchers are increasingly recognizing the critical importance of developing medium- and low-temperature catalysts, particularly those capable of resisting sulfate deposition. Therefore, studying the formation mechanism of ammonium bisulfate will help address ash plugging issues in ultra-low emission denitrification air preheaters and develop medium- and low-temperature catalysts.

[0004] Currently, the controlled condensation method has been widely used in ammonium bisulfate collection, but it also has some shortcomings, resulting in limited test accuracy. The shortcomings of existing sampling equipment are as follows:

[0005] (1) The integration level is very low, and there is a risk of burns when the condensation temperature is high;

[0006] (2) Improvised glassware is inefficient and produces unreliable results;

[0007] (3) The degree of automation is low and the requirements for operators are high. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a device and method for collecting ammonium bisulfate in the flue gas of a coal-fired power plant, which has high integration, high variable control accuracy, high automation degree and is easy to operate.

[0009] The present invention is realized by the following technical solutions:

[0010] A device for collecting ammonium bisulfate in the flue gas of a coal-fired power plant includes a flue gas collection pipeline, a hot air pipe bundle, a flue gas discharge pipeline, a flushing and collection loop and a temperature feedback control system;

[0011] The input end of the hot air pipe bundle is connected to the flue gas collection pipeline through a gas distributor, and the output end is connected to the input end of an expander; the gas outlet of the expander is connected to the flue gas discharge pipeline;

[0012] The flushing and collection loop includes an absorbent liquid tank. The output end of the absorbent liquid tank is connected in parallel with the flue gas collection pipeline at the input end of the hot air pipe bundle, and the input end of the absorbent liquid tank is connected to the liquid outlet of the expander;

[0013] The temperature feedback control system includes a fan controller, a temperature sensor arranged in the hot air pipe bundle, a variable-frequency fan and an electric heating pipe arranged in sequence on one side of the hot air pipe bundle; the input end of the fan controller is connected to the temperature sensor, and the output end is respectively connected to the variable-frequency fan and the electric heating pipe.

[0014] Further, the hot air pipe bundle includes a plurality of parallel air-cooled pipes. Each air-cooled pipe is made of metal and is internally provided with a temperature sensor; the hot air pipe bundle is at least one group, and each group of hot air pipe bundles is vertically installed, and adjacent two groups of hot air pipe bundles are arranged in parallel and stacked.

[0015] Further, the inside of the expander is provided with baffles arranged along the flue gas flow direction.

[0016] Further, a tee is connected to the output end of the expander. One outlet of the tee is the gas outlet, and the other outlet is the liquid outlet.

[0017] Further, a flue gas inlet electric plug valve, a filter type dust collector and a gas flowmeter are sequentially arranged on the flue gas collection pipeline.

[0018] Further, a suction pump and a tail gas absorption device are sequentially arranged on the flue gas discharge pipeline.

[0019] Further, an absorbent liquid inlet electric valve is arranged at the output end of the absorbent liquid tank.

[0020] Further, the temperature feedback control system further includes a control panel connected to the output end of the fan controller, and the control panel is provided with a temperature display.

[0021] A method for collecting ammonium bisulfate in the flue gas of a coal-fired power plant, comprising the following steps:

[0022] S1. Connect the flue gas collection pipeline to the sampling point, and adjust the gas flow velocity in the hot air tube bundle through the flue gas discharge pipeline;

[0023] S2. Start the variable-frequency fan and the electric heating tube. The fan controller controls the gears of the variable-frequency fan and the electric heating tube according to the set condensation temperature, controls the temperature to reach the condensation temperature range, and collects the gas flow rate;

[0024] S3. After reaching the set condensation time, disconnect the flue gas collection pipeline and the flue gas discharge pipe; open the flushing collection loop, start flushing the hot air tube bundle, and collect the absorption liquid for subsequent analysis after flushing is completed.

[0025] Further, after flushing is completed, replace the absorption liquid in the absorption liquid tank with deionized water, and flush the hot air tube bundle and the expansion vessel at least 3 times.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] The system of the present invention connects the flue gas collection pipeline and the flue gas discharge pipeline to the hot air tube bundle, and uses the condensation method to condense all the ammonium bisulfate in the flue gas onto the inner wall of the hot air tube bundle, the surface of the expansion vessel and the bottom of the expansion vessel, and fully absorbs the condensed ammonium bisulfate droplets with the absorption liquid, and waits for subsequent analysis to obtain the ammonium bisulfate content; moreover, the hot air tube bundle is used to provide the ambient temperature for ammonium bisulfate condensation. On the one hand, it is convenient to accurately control the condensation temperature, and on the other hand, it reduces the volume of the condensation device; at the same time, applying the absorption liquid to flush the condensation product is beneficial to improving the absorption efficiency and measurement accuracy; since the temperature feedback adjustment control system is adopted, there is no need for frequent manual operation, the system integration degree is high, and only the sample liquid needs to be collected, which greatly improves the automatic operation degree of the system; the system of the present invention overcomes the shortcomings of the traditional sampling equipment system with complex structure, cumbersome operation and low system stability, realizes accurate and efficient operation of ammonium bisulfate sampling, and has practical significance for studying the ammonium bisulfate concentration of SCR denitration equipment.

[0028] Further, the cold air tube material of the hot air tube bundle in the system of the present invention is made of a metal material with good heat transfer effect. At the same time, the hot air tube bundle includes multiple parallel air-cooled tubes and the hot air tube bundle is at least one group, effectively ensuring the condensation effect.

[0029] Further, the system of the present invention uses an expansion vessel to slow down the flow velocity of the flue gas and the condensed droplets (crystals) carried by the flue gas, and by arranging baffles along the flue gas flow direction inside the expansion vessel, the droplets (crystals) can be intercepted to achieve gas-liquid (solid) separation, thereby effectively improving the condensation effect.

[0030] Furthermore, the system of the present invention adopts a method of setting a tee at the output end of the flash tank, which can conveniently realize the switching between the flue gas path and the absorption liquid path, facilitate the collection of the absorption liquid, and improve the working efficiency.

[0031] Furthermore, the system of the present invention is provided with a filter type dust collector on the flue gas collection pipeline to separate the fly ash in the flue gas; at the same time, a gas flow meter is also provided to detect the gas flow rate, enabling the operator to adjust the condensation speed according to the actual situation at any time and record parameters such as the flow rate and volume of the collected flue gas.

[0032] Furthermore, the system of the present invention is sequentially provided with a suction pump and a tail gas absorption device on the flue gas discharge pipeline to accelerate the discharge of the flue gas and effectively carry out absorption treatment.

[0033] Furthermore, the system of the present invention is provided with an electric control valve at the output end of the absorption liquid tank, which improves the degree of automation and is convenient to operate.

[0034] Furthermore, the system of the present invention adopts a temperature feedback control system connected to the electric heating tube, and transmits the temperature information to the temperature display on the control panel, and the result is displayed on the display screen of the control panel, which is convenient for the operator to manually control and adjust the condensation process when necessary and can obtain relevant sampling data in real time.

[0035] The method of the present invention has a high degree of integration and can realize automatic control, avoiding the influence of factors such as easy damage of glass instruments, low airtightness of the device, complex and dangerous water bath heating operation in the traditional sampling method, and can realize accurate and efficient sampling operation of ammonium bisulfate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram in an embodiment of the present invention.

[0037] Figure 2 It is a schematic diagram of the position arrangement of the hot air duct bundle group, variable frequency fan and electric heating tube of the present invention.

[0038] Figure 3 It is a schematic cross-sectional structure diagram of the hot air duct bundle of the present invention.

[0039] In the figure: 1. Electric plug valve for flue gas inlet, 2. Filter type dust collector, 3. Gas flow meter, 4. Gas distributor, 5. Hot air duct bundle, 6. Variable frequency fan, 7. Temperature sensor, 8. Baffle plate, 9. Flash tank, 10. Air extraction pump, 11. Electric control valve for absorption liquid inlet, 12. Fan controller, 13. Control panel, 14. Electric heating tube, 15. Tail gas absorption device, 16. Absorption liquid tank, 17. Temperature display. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings. The following is an explanation of the present invention rather than a limitation.

[0041] An ammonium bisulfate collection device in the flue gas of a coal-fired power station according to the present invention, as Figure 1 and Figure 2 shown, includes a flue gas collection pipeline, a hot air pipe bundle 5 and a flue gas discharge pipeline, as well as a flushing and collection circuit and a temperature feedback control system; specifically includes a flue gas inlet electric slide gate 1, a filter-type dust collector 2, a gas flow meter 3, a gas distributor 4, a hot air pipe bundle 5, a variable-frequency fan 6, a temperature sensor 7, a baffle 8, an expander 9, an air extraction pump 10, a fan controller 12, a control panel 13, an electric heating tube 14, a temperature display 17, a flue gas discharge pipeline, a tail gas absorption device 15, an absorption liquid tank 16 and an absorption liquid inlet electric valve 11;

[0042] The filter-type dust collector 2 is connected to the gas flow meter 3 downstream of the flue gas inlet electric slide gate 1; the input end of the hot air pipe bundle 5 is connected to the flue gas collection pipeline through the gas distributor 4; the flue gas collection pipeline after the gas flow meter 3 and the output end of the absorption liquid tank 16 are connected in parallel to the input end of the hot air pipe bundle 5; the input end of the expander 9 is connected to the output end of the hot air pipe bundle 5, and the output end of the expander 9 is connected to a tee. One outlet of the tee is a gas outlet, and the other outlet is a liquid outlet; the baffle 8 is located inside the expander 9; the air extraction pump 10 is connected to the gas outlet of the tee; the tail gas absorption device 15 is connected to the air extraction pump 10; the input end of the absorption liquid tank 16 is connected to the liquid outlet of the tee; the absorption liquid inlet electric valve 11 is connected to the absorption liquid tank 16 through a pipeline; the temperature sensor 7 is respectively arranged inside multiple air-cooled pipes of the hot air pipe bundle 5 and is connected to the input end of the fan controller 12 through a wire; as Figure 2 shown, the variable-frequency fan 6 is located on the side of the hot air pipe bundle 5 and is connected to the output end of the fan controller 12 through a wire, and the electric heating tube 14 is located on the other side of the variable-frequency fan 6 relative to the hot air pipe bundle 5; the control panel 13 is connected to the output end of the fan controller 12 through a wire.

[0043] Among them, a gas flow meter 3 is arranged on the passage where the flue gas inlet pipe bundle of the flue gas collection pipeline is located, which can detect the gas flow rate, enabling the operator to adjust the condensation speed according to the actual situation at any time and record parameters such as the flow rate and volume of the collected flue gas.

[0044] Among them, the temperature feedback control system composed of the temperature sensor 7, the fan controller 12, and the variable-frequency fan 6 transmits the temperature information in the hot air duct bundle 5 to the fan controller 12 for processing, and controls the rotation speed of the variable-frequency fan 6 and the temperature of the electric heating tube 14, and finally controls the temperature of the hot air duct bundle 5. Specifically, the temperature sensor 7 is connected to the input end of the fan controller 12. The temperature sensor 7 converts the temperature information in the hot air duct bundle 5 into an electrical signal and transmits it to the fan controller 12. The fan controller 12 compares the feedback temperature signal with the set temperature and controls the rotation speed of the variable-frequency fan 6, so as to control the temperature in the hot air duct bundle 5 within the set temperature. Therefore, the integration degree of this embodiment is relatively high, and it can achieve automatic control, avoiding the disadvantages of complex operation and low precision in traditional sampling methods, and realizing accurate and efficient ammonium bisulfate sampling operations.

[0045] Among them, at least one group of the hot air duct bundles 5 is provided, and each group is vertically loaded, and two adjacent groups are arranged horizontally; the cold air duct of the hot air duct bundle 5 is made of a metal material with good heat transfer effect.

[0046] Among them, as Figure 3 shown, the hot air duct bundle 5 can provide five flue gas passages, increasing the contact area between the flue gas and the metal, improving the heat exchange efficiency and the condensation efficiency; at the same time, the hot air duct bundle group and the variable-frequency fan 6 can provide a constant temperature environment of about 200 °C, so as to achieve selective and stable condensation.

[0047] Among them, the current of the variable-frequency fan 6 is adjusted through the control panel 13 and the temperature feedback control system to achieve adjustable temperature.

[0048] Among them, the absorption liquid tank 16, the absorption liquid inlet electric door 11, and the three-way joint can wash and collect the condensation products in the hot air duct bundle 5. Specifically, the absorption liquid tank 16 and the absorption liquid inlet electric door 11 are arranged on the flushing and collection loop, so that the hot air duct bundle 5 can be flushed after condensation is completed, and the condensation products are absorbed. The three-way joint at the bottom of the expansion vessel 9 can realize the switching between the flue gas path and the absorption liquid path.

[0049] Among them, the air extraction pump 10 is arranged at the rear end of the flue gas discharge pipeline, which can overcome the negative pressure of the flue and extract the sample gas, and control the flow rate of the sample gas in the condensation path to ensure the condensation effect.

[0050] In practical applications, when using this embodiment for ammonium bisulfate sampling of power plant flue gas, the following operation steps are included:

[0051] S1. The sampling device instrument is powered on for self-checking;

[0052] S2. Connect the flue gas collection pipeline of the sampling device to the sampling point, open the flue gas inlet electric plug door 1, start the air extraction pump 10, and adjust the power of the air extraction pump 10 to realize the adjustment of the air flow rate;

[0053] S3. Start the variable-frequency fan 6 and the electric heating tube 14, set the condensation temperature and the gear of the electric heating tube 14. When the temperature reaches the condensation temperature range, start the gas flowmeter 3;

[0054] S4. Start sampling. After sampling is completed, close the flue gas inlet electric slide gate 1, and then sequentially close the air extraction pump 10 and the gas flowmeter 3; adjust the variable-frequency fan 6 to the cold air gear. After the temperature of the sampling tube decreases, open the absorption liquid inlet electric door 11 to start flushing. After flushing is completed, switch the three-way valve to the liquid outlet to collect the absorption liquid for subsequent analysis;

[0055] S5. After sampling is completed, replace the absorption liquid in the absorption liquid tank 16 with deionized water and flush the sampling circuit at least 3 times.

[0056] In the above step S1, the self-inspection items include electrical short circuit, calibration of the gas flowmeter 3, and whether each component operates normally; the main components include the variable-frequency fan 6, the air extraction pump 10, the absorption liquid inlet electric door 11, the flue gas inlet electric slide gate 1, the fan controller 12, the control panel 13, the temperature display 17, the gas flowmeter 3, and the temperature sensor 7, etc.

[0057] In summary, in the present invention, the condensation pipe path is arranged in the hot air duct bundle 5 and is connected to the inlet pipe of the flue gas collection pipeline at the upper end. The convective heat transfer principle is used to make the flue gas in the hot air duct bundle 5 reach the condensation temperature of ammonium bisulfate; a filter-type dust collector 2 is arranged on the inlet pipe of the flue gas collection pipeline to separate the fly ash in the flue gas; an absorption liquid tank 16 is arranged inside the device to store the absorption liquid. After condensation is completed, the condensation products on the condensation pipe wall can be flushed out to facilitate the detection of the ammonium bisulfate content; the expansion vessel 9 is used to slow down the flow rate of the flue gas and the condensed liquid droplets (crystals) carried by the flue gas. The baffle 8 in the expansion vessel 9 can intercept the liquid droplets (crystals) to achieve gas-liquid (solid) separation; the three-way valve can switch the path to facilitate the collection of the absorption liquid; the fan controller 12 serves as the processor of the temperature feedback control system, receives the signal of the temperature sensor 7 and controls the rotation speed of the variable-frequency fan 6; the temperature feedback control system is connected to the electric heating tube 14 and transmits the temperature information to the temperature display 17 on the control panel 13, and the result is displayed on the display screen of the control panel 13, which is convenient for the operator to manually control and adjust the condensation process when necessary. The present invention has a high degree of automation and high measurement accuracy, and will also promote the engineering applications related to the research of ammonium bisulfate.

[0058] Based on the above device, the present invention also provides a method for collecting ammonium bisulfate in the flue gas of a coal-fired power station, including the following steps,

[0059] S1. Connect the flue gas collection pipeline to the sampling point and adjust the gas flow rate in the hot air duct bundle 5 through the flue gas discharge pipeline;

[0060] S2. Start the variable-frequency fan 6 and the electric heating tube 14. The fan controller 12 controls the gears of the variable-frequency fan 6 and the electric heating tube 14 according to the set condensation temperature, controls the temperature to reach the condensation temperature range, and collects the gas flow rate.

[0061] S3. After reaching the condensation set time, disconnect the flue gas collection pipeline and the flue gas discharge pipe; open the flushing collection circuit, start flushing the hot air tube bundle 5, and collect the absorption liquid after flushing for subsequent analysis.

[0062] Among them, after flushing, replace the absorption liquid in the absorption liquid tank 16 with deionized water, and flush the hot air tube bundle 5 and the expander 9 at least 3 times.

[0063] Finally, it should be noted that for the specific embodiments described in this specification, the shapes, names of the components, etc. can be different. Any equivalent or simple changes made according to the structure, features, and principles described in the inventive concept of this invention patent are included in the protection scope of this invention patent. Those skilled in the technical field to which this invention pertains can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the structure of this invention or exceed the scope defined by this claim book, they should all fall within the protection scope of this invention.

Claims

1. An ammonium bisulfate collection device in the flue gas of a coal-fired power station, characterized in that, It includes a smoke collection pipeline, a hot air pipe bundle (5) and a smoke exhaust pipeline, as well as a flushing collection circuit and a temperature feedback control system; The input end of the hot air tube bundle (5) is connected to the flue gas collection pipeline via the gas distributor (4), and the output end is connected to the input end of the expander (9); the gas outlet of the expander (9) is connected to the flue gas exhaust pipeline; The hot air pipe bundle (5) includes a plurality of parallel air cooling pipes, each air cooling pipe is made of metal and is provided with a temperature sensor (7) therein; the hot air pipe bundle (5) is at least one group, each group of hot air pipe bundles (5) is vertically installed, and two adjacent groups of hot air pipe bundles (5) are arranged in parallel and stacked; The expander (9) is provided with folding plates (8) arranged along the direction of smoke flow; The flushing and collecting circuit includes an absorption liquid tank (16), the output end of the absorption liquid tank (16) and the flue gas collection pipeline are connected in parallel to the input end of the hot air tube bundle (5), and the input end of the absorption liquid tank (16) is connected to the liquid outlet of the expansion tank (9); The temperature feedback control system comprises a fan controller (12), a temperature sensor (7) arranged in the hot air tube bundle (5), a variable frequency fan (6) and an electric heating pipe (14) arranged in sequence on one side of the hot air tube bundle (5); the variable frequency fan (6) is located on the side of the hot air tube bundle (5), and the electric heating pipe (14) is located on the other side of the variable frequency fan (6) relative to the hot air tube bundle (5), and the convection heat transfer principle is used to make the flue gas in the hot air tube bundle (5) reach the condensation temperature of ammonium bisulfate; The input end of the fan controller (12) is connected to the temperature sensor (7), and the output end is respectively connected to the variable frequency fan (6) and the electric heating tube (14).

2. The ammonium bisulfate collection device in the flue gas of a coal-fired power station according to claim 1, wherein, The output end of the expansion container (9) is connected to a tee, one outlet of the tee is a gas outlet, and the other outlet is a liquid outlet.

3. The sampling device for ammonium bisulfate in the flue gas of a coal-fired power station according to claim 1, wherein The flue gas collection pipeline is provided with a flue gas inlet electric plug-in door (1), a filter-type dust collector (2) and a gas flow meter (3) in sequence.

4. The sampling device for ammonium bisulfate in the flue gas of a coal-fired power station according to claim 1, wherein The smoke exhaust pipeline is provided with a suction pump (10) and a tail gas absorption device (15) in sequence.

5. The sampling device for ammonium bisulfate in the flue gas of a coal-fired power station according to claim 1, wherein The output end of the absorption liquid tank (16) is provided with an absorption liquid inlet electric door (11).

6. The sampling device for ammonium bisulfate in the flue gas of a coal-fired power station according to claim 1, characterized in that, The temperature feedback control system further comprises a control panel (13) connected to the output end of the fan controller (12), and the control panel (13) is provided with a temperature display (17).

7. A method for collecting ammonium bisulfate in the flue gas of a coal-fired power plant, characterized in that, The device according to any one of claims 1 to 6 comprises the following steps: S1. Connect the flue gas collection pipe to the sampling point and adjust the air flow velocity within the hot air bundle (5) through the flue gas exhaust pipe; S2 starts the variable frequency fan (6) and the electric heating tube (14), the fan controller (12) controls the gear of the variable frequency fan (6) and the electric heating tube (14) according to the set condensing temperature, controls the temperature to reach the condensing temperature range, and collects the gas flow; S3. After the condensation setting time is reached, the flue gas collection pipeline and the flue gas exhaust pipe are disconnected; the flushing collection loop is opened and the hot air tube bundle (5) is started to be flushed. After the flushing is completed, the absorption liquid is collected for subsequent analysis.

8. A method for collecting ammonium bisulfate in the flue gas of a coal-fired power plant according to claim 7, characterized in that, After rinsing is completed, replace the absorbent liquid in the absorbent liquid tank (16) with deionized water, and rinse the hot air duct bundle (5) and the expansion vessel (9) at least three times.

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