Desulfurization wastewater flue gas drying system with temperature compensation function

Abstract

A desulfurization waste water flue gas drying system with a temperature compensation function comprises a flue gas mixer, the leading-in end of the flue gas mixer is connected with a low-temperature flue gas pipeline and a high-temperature flue gas pipeline respectively, the leading-out end of the flue gas mixer is provided with a flue gas leading-in pipeline, the flue gas leading-in pipeline is connected with a drying spray tower, and the drying spray tower is connected with the flue gas mixer. And the drying spray tower is also connected with a desulfurization wastewater pipeline. The flue gas mixer is adopted to mix the low-temperature flue gas pipeline and the high-temperature flue gas pipeline, and then energy is supplied to the drying spray tower, so that the wastewater introduced from the desulfurization wastewater pipeline can be dried as soon as possible according to requirements, and various problems caused by unsmooth adjustment are avoided.

Description

Technical Field

[0001] The present application relates to a desulfurization wastewater flue gas drying system with supplementary temperature. Background Art

[0002] In the treatment of desulfurization wastewater, the traditional spray drying technology is used. The desulfurization wastewater is atomized into fine droplets with a particle size of about 10-60μm by a rotary atomizer and sprayed into the drying tower. The hot flue gas from the boiler before the air preheater is used as a heat source. The wastewater is evaporated in the spray drying tower through the bypass flue, and the water enters the flue gas. After drying, part of the salt in the wastewater falls to the bottom of the drying tower and is collected and transported. The remaining dry products enter the dust collector with the flue gas for treatment, thereby achieving the purpose of zero discharge of desulfurization wastewater.

[0003] Under the current energy transformation background of coal-fired power units, they are often in deep peak-shaving operation mode, which requires the bypass flue gas volume adjustment range of the bypass flue to be wide enough to meet the requirements of flexible operation of the unit. However, under extremely low load, on the one hand, the amount of desulfurization wastewater generated is limited; on the other hand, the temperature of the bypass flue gas is greatly reduced. Even if the bypass flue gas volume is the largest, it cannot meet the heat requirements of drying desulfurization wastewater and the wide load operation mode of the unit, and will eventually lead to dust accumulation, scaling, blockage, corrosion and other problems in the drying tower. Summary of the invention

[0004] In order to solve the above problems, the present application proposes a flue gas drying system for desulfurization wastewater with supplementary temperature, including a flue gas mixer, the inlet end of the flue gas mixer is respectively connected to the low-temperature flue gas pipeline and the high-temperature flue gas pipeline, and an inlet flue gas pipeline is arranged at the outlet end of the flue gas mixer, the inlet flue gas pipeline is connected to the drying spray tower, and the drying spray tower is also connected to the desulfurization wastewater pipeline. The present application adopts a flue gas mixer to mix the low-temperature flue gas pipeline and the high-temperature flue gas pipeline, and then supplies energy to the drying spray tower, so that the wastewater introduced from the desulfurization wastewater pipeline can complete the drying as soon as possible to meet the requirements, avoiding various problems caused by poor regulation.

[0005] Preferably, the flue gas mixer comprises a mixing shell, the low-temperature flue gas duct leads into the mixing shell from a side, and the high-temperature flue gas duct leads into the mixing shell from an axial direction.

[0006] Preferably, it also includes a plurality of economizers connected to the boiler, and the low-temperature flue gas duct is connected to the rear end of the economizer; a denitrification reactor, a low-temperature baffle and a low-temperature regulating valve are arranged on the low-temperature flue gas duct.

[0007] Preferably, the low-temperature flue gas duct is further provided with an air preheater branch pipe, and the air preheater branch pipe is connected to the air preheater.

[0008] Preferably, a plurality of lateral connecting pipes are arranged between economizers and / or between economizers and heat exchange pipes and / or between heat exchange pipes, and the lateral connecting pipes are connected to the high-temperature flue gas pipe, a high-temperature regulating valve is also arranged on the high-temperature flue gas pipe, and a side baffle is arranged on the lateral connecting pipe. The present application controls the temperature of the introduced flue gas by the position of the lateral connecting pipe, mainly because the adjustment of the boiler load is gradual, and this method is just adapted to its gradualness, and can ensure the drying effect while saving energy as much as possible.

[0009] Preferably, the flue gas outlet end of the air preheater is connected to the electrostatic precipitator, the induced draft fan and the desulfurizer in sequence, and then introduced into the flue gas introduction duct.

[0010] Preferably, the dry spray tower is provided with a powder outlet at the bottom of the dry spray tower, a spray outlet pipe is provided on the side of the dry spray tower, the spray outlet pipe is connected to the pipes of the air preheater and the electrostatic precipitator, and a residue valve is provided on the spray outlet pipe.

[0011] Preferably, a temperature monitor is also provided on the air preheater branch pipe;

[0012] When the power plant boiler is transformed from a high-load operation state to a low-load operation state, the monitoring temperature of the temperature monitor exceeds the set temperature, the low-temperature flue gas duct is opened, and the high-temperature flue gas duct is closed. The drying effect of the spray drying tower is monitored by the monitoring temperature of the temperature monitor. When the temperature is too low, the flow rate of the low-temperature flue gas duct is increased to control the high-load operation requirements. When the low-temperature flue gas duct is adjusted to the maximum flow rate, the outflow flow rate of the drying spray tower reaches the maximum flow rate, and the monitoring temperature of the temperature monitor drops to the set temperature, the critical load state is reached;

[0013] When the load is lower than the critical load, the high-temperature flue gas duct is gradually opened, and the high-temperature flue gas entering the flue gas mixer is adjusted by adjusting the flow rate of the high-temperature flue gas duct so that the monitoring temperature of the temperature monitor is not lower than the set temperature;

[0014] When opening the high-temperature flue gas duct, the lateral connecting ducts are opened in the order of the lateral connecting ducts between economizers, the lateral connecting ducts between economizers and heat exchange ducts, and the lateral connecting ducts between heat exchange ducts.

[0015] When the power plant boiler is converted from a low-load operating state to a high-load operating state, the above-mentioned operating steps are performed in reverse.

[0016] Preferably, the flue gas housing includes a mixing pipe, a side channel is arranged on one side of the mixing pipe, the low-temperature flue gas pipe is connected to the side channel, the introduction flue gas pipe is connected to the mixing pipe away from the side channel, an introduction pipe is arranged in the middle of the mixing pipe close to the side channel, the introduction pipe is connected to the high-temperature flue gas pipe, and the other end of the introduction pipe is inserted into the mixing pipe and arranged coaxially with the mixing pipe;

[0017] The inlet pipe is a truncated cone-shaped pipe with a gradually decreasing inner diameter;

[0018] A first mixing plate is arranged between the inlet pipe and the mixing pipe, and a second mixing plate is arranged at one end of the mixing pipe away from the inlet pipe. The distance between the first mixing plate and the second mixing plate is not less than the diameter of the mixing pipe and not more than twice the diameter of the mixing pipe.

[0019] Preferably, the first mixing plate is provided with a plurality of vertically arranged ray strip holes with the center as the radiation center, and the distribution density of the ray strip holes on one side of the side channel is not more than 0.6 times the distribution density of the ray strip holes on the other side;

[0020] The second mixing plate is provided with a plurality of annular channels arranged in an annular manner, each of which includes a plurality of arc-shaped holes arranged at intervals, and the intervals between the annular channels are the same. The present application adopts a first mixing plate with ray-shaped holes and a second mixing plate with annular channels to ensure that the smoke introduced into the first mixing plate is relatively evenly introduced into the annular channels, and then the internal smoke is mixed by the second mixing plate.

[0021] This application can bring the following beneficial effects:

[0022] 1. This application uses a flue gas mixer to mix the low-temperature flue gas pipeline and the high-temperature flue gas pipeline, and then supplies energy to the drying spray tower, so that the wastewater introduced from the desulfurization wastewater pipeline can be dried as soon as possible to meet the requirements, avoiding various problems caused by poor regulation.

[0023] 2. The present application controls the temperature of the introduced flue gas by the position of the lateral connecting pipe. This is mainly because the adjustment of the boiler load must be gradual. This method is just adapted to its gradualness and can ensure the drying effect while saving energy as much as possible.

[0024] 3. The present application adopts a first mixing plate with ray-shaped holes and a second mixing plate with an annular channel, which can ensure that the smoke introduced into the first mixing plate is relatively evenly introduced into the annular channel, and then the internal smoke is mixed by the second mixing plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0026] Figure 1 This is a schematic diagram of the process of this application.

[0027] Figure 2 Schematic diagram of the flue gas mixer.

[0028] Figure 3 Schematic diagram of the first mixing plate.

[0029] Figure 4 Schematic diagram of the second mixing plate. DETAILED DESCRIPTION

[0030] In order to clearly illustrate the technical features of the present solution, the present application is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0031] like Figure 1-4 As shown, a flue gas drying system for desulfurization wastewater with supplementary temperature includes a flue gas mixer 1, the inlet end of the flue gas mixer 1 is connected to a low-temperature flue gas pipeline 2 and a high-temperature flue gas pipeline 3 respectively, and an inlet flue gas pipeline 4 is arranged at the outlet end of the flue gas mixer 1, the inlet flue gas pipeline 4 is connected to a drying spray tower 5, and the drying spray tower 5 is also connected to a desulfurization wastewater pipeline 6.

[0032] The flue gas mixer 1 comprises a mixing shell, the low-temperature flue gas duct 2 is introduced from the side of the mixing shell, and the high-temperature flue gas duct 3 is introduced from the axial direction of the mixing shell.

[0033] It also includes a plurality of economizers 8 connected to the boiler 7, and the low-temperature flue gas duct 2 is connected to the rear end of the economizer 8; a denitration reactor 18, a low-temperature baffle 201 and a low-temperature regulating valve 101 are arranged on the low-temperature flue gas duct 2. The low-temperature flue gas duct 2 is also provided with an air preheater branch pipe 9, and the air preheater branch pipe 9 is connected to the air preheater 10. A plurality of lateral connecting pipes 12 are arranged between the economizers 8 and / or between the economizers 8 and the heat exchange pipes 11 and / or between the heat exchange pipes 11, and the lateral connecting pipes 12 are connected to the high-temperature flue gas duct 3, and a high-temperature regulating valve 102 is also arranged on the high-temperature flue gas duct 3. A side baffle is arranged on the lateral connecting pipe 12, as shown in the figure, it is a side baffle 203, a side baffle 204 and a side baffle 205. The flue gas outlet end of the air preheater 10 is connected to the electrostatic precipitator 13, the induced draft fan 14, and the desulfurizer 15 in sequence, and then introduced into the flue gas introduction pipe 4. The drying spray tower 5 is provided with a powder outlet 16 at the bottom of the drying spray tower 5, and a spray outlet pipe 17 is provided on the side of the drying spray tower 5. The spray outlet pipe 17 is connected to the pipes of the air preheater 10 and the electrostatic precipitator 13, and a residue valve 202 is provided on the spray outlet pipe 17.

[0034] A temperature monitor 301 is also provided on the air preheater branch pipe 9;

[0035] When the power plant boiler 7 is transformed from a high-load operation state to a low-load operation state, the monitoring temperature of the temperature monitor exceeds the set temperature, the low-temperature flue gas duct 2 is opened, and the high-temperature flue gas duct 3 is closed. The drying effect of the spray drying tower is monitored by the monitoring temperature of the temperature monitor. When the temperature is too low, the flow rate of the low-temperature flue gas duct 2 is increased to control the high-load operation requirements. When the low-temperature flue gas duct 2 is adjusted to the maximum flow rate, the outflow flow rate of the drying spray tower 5 reaches the maximum flow rate, and the monitoring temperature of the temperature monitor drops to the set temperature, the critical load state is reached.

[0036] When the load is lower than the critical load, the high-temperature flue gas duct 3 is gradually opened, and the high-temperature flue gas entering the flue gas mixer 1 is adjusted by adjusting the flow rate of the high-temperature flue gas duct 3 so that the monitoring temperature of the temperature monitor is not lower than the set temperature;

[0037] When the high-temperature flue gas duct 3 is opened, the lateral connecting ducts 12 are opened in the following order: the lateral connecting ducts 12 between the economizers 8, the lateral connecting ducts 12 between the economizers 8 and the heat exchange ducts 11, and the lateral connecting ducts 12 between the heat exchange ducts 11;

[0038] When the power station boiler 7 is transformed from a low-load operation state to a high-load operation state, the reverse operation is performed according to the above operation steps.

[0039] Specifically, the steps are as follows:

[0040] When the power plant boiler 7 is in high-load operation, the temperature of the temperature monitor 301 is greater than the set temperature T1, 201 and 202 are fully open, 101 is turned on, 203, 204, 205 and 102 are closed, and the temperature compensation system is disconnected. At this time, the drying effect of the spray drying tower is monitored by the temperature measuring point of the temperature monitor 301. When the temperature is too low, the drying flue gas flow rate is controlled by the opening of 101 to meet the high-load operation requirements. When 203, 204, 205 and the regulating door 102 are closed; 201, 202 are fully open; 101 is fully open, the temperature monitor 301 reaches the set temperature T1, which is a critical load state.

[0041] When it is lower than the critical load state, the temperature of the bypass flue gas before the air preheater continues to decrease. When 101 is fully opened, the temperature of the temperature monitor 301 is less than T1. At this time, 203 is opened to introduce the high-temperature flue gas before the economizer 8 for temperature supplement. The temperature supplement system is turned on, and by adjusting the opening of the regulating door 102, the high-temperature flue gas after the economizer 8 is introduced into the flue gas before the air preheater. After sufficient mixing, the drying performance of the spray drying tower is improved, and the outlet temperature of the dry wet air is maintained, so that TI301 exceeds T1.

[0042] As the load continues to decrease, the regulating door 102 is fully opened, the temperature of the temperature monitor 301 is less than T1, 203 is closed, 204 is opened, and the high-temperature flue gas before the economizer 8 is introduced to make up the temperature. By adjusting the opening of 102 and fully mixing, the drying performance of the spray drying tower is improved, the outlet temperature of the dry wet air is maintained, and T301 exceeds T1.

[0043] After the load is further reduced to an ultra-low load, the regulating door 102 is fully opened, and the temperature of the temperature monitor 301 is still lower than T1. 204 is closed and 205 is opened to introduce the high-temperature flue gas before the superheater to make up the temperature. By adjusting the opening of 102, the high-temperature flue gas before the superheater is induced into the flue gas before the air preheater. After sufficient mixing, the drying performance of the spray drying tower is improved, the outlet temperature of the dry wet air is maintained, and the temperature of the temperature monitor 301 exceeds T1.

[0044] In the embodiment, when the load increases from low, the above operation is performed in reverse to maintain the outlet temperature of dry humid air and make the temperature of the temperature monitor 301 exceed T1.

[0045] The flue gas housing includes a mixing pipe 18, a side channel 19 is arranged on one side of the mixing pipe 18, the low-temperature flue gas pipe 2 is connected to the side channel 19, the inlet flue gas pipe 4 is connected to the mixing pipe 18 away from the side channel 19, an inlet pipe 20 is arranged in the middle of the mixing pipe 18 close to the side channel 19, the inlet pipe 20 is connected to the high-temperature flue gas pipe 3, and the other end of the inlet pipe 20 is inserted into the mixing pipe 18 and arranged coaxially with the mixing pipe 18; the inlet pipe 20 is a truncated cone-shaped pipe with a tapered inner diameter; a first mixing plate 21 is arranged between the inlet pipe 20 and the mixing pipe 18, and a second mixing plate 22 is arranged at the end of the mixing pipe 18 away from the inlet pipe 20, and the distance between the first mixing plate 21 and the second mixing plate 22 is not less than the diameter of the mixing pipe 18 and not more than 2 times the diameter of the mixing pipe 18. The first mixing plate 21 is provided with a plurality of vertically arranged ray strip holes 23 with the center as the radiation center, and the distribution density of the ray strip holes 23 located on one side of the side channel 19 is not more than 0.6 times the distribution density of the ray strip holes 23 on the other side; the second mixing plate 22 is provided with a plurality of annular channels 24 arranged in an annular manner, each annular channel 24 includes a plurality of arc holes 25 arranged at intervals, and the interval distances between each annular channel 24 are the same.

[0046] The temperature compensation system of the present invention makes full use of the high temperature heat of the flue gas in the boiler 7. The high temperature flue gas enters the drying tower through the temperature compensation device, and the inlet flue gas temperature of the drying tower is increased, so that the bypass flue gas heat can meet the evaporation requirements of the drying waste liquid, ensuring the safe and reliable operation of the zero discharge system of desulfurization wastewater under a wide load, and adapting to the deep peak load operation mode requirements of the unit. The scheme has the following advantages:

[0047] Improve the air preheater bypass flue gas temperature: The air preheater bypass flue gas temperature supplement system can significantly increase the air preheater bypass flue gas temperature, usually by 60℃-100℃. This measure helps to fully and effectively utilize the thermal energy of boiler 7 when it is running at low load.

[0048] Enhance system safety and stability: Under ultra-low load, the flue gas temperature at the inlet of the drying tower is increased, so that the heat of the bypass flue gas can meet the evaporation of the drying waste liquid, adapting to the wide load operation mode of the unit. At the same time, it can also reduce the dust accumulation, scaling and corrosion of the drying tower wall in a low temperature and high humidity environment, extend the service life of the equipment, and improve the stability of operation.

[0049] Improve system flexibility and adapt to various load conditions: The temperature compensation system enables the desulfurization wastewater flue gas drying system to operate normally when boiler 7 is running at low load, thereby enhancing the system's adaptability to various load conditions.

[0050] Easy to maintain and adjust: The system design is usually simple, with relatively few newly installed pipelines and equipment, making daily maintenance and adjustment easier.

[0051] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A desulfurization wastewater flue gas drying system with temperature compensation, characterized in that: It includes a flue gas mixer, the inlet end of which is connected to a low-temperature flue gas pipeline and a high-temperature flue gas pipeline respectively, and an inlet flue gas pipeline is arranged at the outlet end of the flue gas mixer, the inlet flue gas pipeline is connected to a drying spray tower, and the drying spray tower is also connected to a desulfurization wastewater pipeline.

2. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 1, characterized in that: The flue gas mixer comprises a mixing shell, the low-temperature flue gas duct leads into the mixing shell from the side, and the high-temperature flue gas duct leads into the mixing shell from the axial direction.

3. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 1, characterized in that: It also includes a plurality of economizers connected to the boiler, and the low-temperature flue gas pipeline is connected to the rear end of the economizer; a denitrification reactor, a low-temperature baffle and a low-temperature regulating valve are arranged on the low-temperature flue gas pipeline.

4. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 3, characterized in that: The low-temperature flue gas duct is also provided with an air preheater branch pipe, and the air preheater branch pipe is connected to the air preheater.

5. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 3, characterized in that: A plurality of lateral connecting pipes are arranged between economizers and / or between economizers and heat exchange pipes and / or between heat exchange pipes. The lateral connecting pipes are connected to the high-temperature flue gas pipes. A high-temperature regulating valve is also arranged on the high-temperature flue gas pipe. A side baffle is arranged on the lateral connecting pipes.

6. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 4, characterized in that: The flue gas outlet end of the air preheater is connected to the electrostatic precipitator, the induced draft fan and the desulfurizer in sequence, and then introduced into the flue gas introduction duct.

7. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 6, characterized in that: The dry spray tower is provided with a powder outlet at the bottom of the dry spray tower, a spray outlet pipe is provided at the side of the dry spray tower, the spray outlet pipe is connected with the pipes of the air preheater and the electrostatic precipitator, and a residue valve is provided on the spray outlet pipe.

8. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 5, characterized in that: A temperature monitor is also provided on the air preheater branch pipe; When the power plant boiler is transformed from a high-load operation state to a low-load operation state, the monitoring temperature of the temperature monitor exceeds the set temperature, the low-temperature flue gas duct is opened, and the high-temperature flue gas duct is closed. The drying effect of the spray drying tower is monitored by the monitoring temperature of the temperature monitor. When the temperature is too low, the flow rate of the low-temperature flue gas duct is increased to control the high-load operation requirements. When the low-temperature flue gas duct is adjusted to the maximum flow rate, the outflow flow rate of the drying spray tower reaches the maximum flow rate, and the monitoring temperature of the temperature monitor drops to the set temperature, the critical load state is reached; When the load is lower than the critical load, the high-temperature flue gas duct is gradually opened, and the high-temperature flue gas entering the flue gas mixer is adjusted by adjusting the flow rate of the high-temperature flue gas duct so that the monitoring temperature of the temperature monitor is not lower than the set temperature; When opening the high-temperature flue gas duct, the lateral connecting ducts are opened in the order of the lateral connecting ducts between economizers, the lateral connecting ducts between economizers and heat exchange ducts, and the lateral connecting ducts between heat exchange ducts. When the power plant boiler is converted from a low-load operating state to a high-load operating state, the above-mentioned operating steps are performed in reverse.

9. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 1, characterized in that: The flue gas housing comprises a mixing pipe, a side channel is arranged on one side of the mixing pipe, the low-temperature flue gas pipe is connected to the side channel, the introduction flue gas pipe is connected to the mixing pipe far away from the side channel, an introduction pipe is arranged in the middle of the mixing pipe close to the side channel, the introduction pipe is connected to the high-temperature flue gas pipe, and the other end of the introduction pipe is inserted into the mixing pipe and arranged coaxially with the mixing pipe; The inlet pipe is a truncated cone-shaped pipe with a gradually decreasing inner diameter; A first mixing plate is arranged between the inlet pipe and the mixing pipe, and a second mixing plate is arranged at one end of the mixing pipe away from the inlet pipe. The distance between the first mixing plate and the second mixing plate is not less than the diameter of the mixing pipe and not more than twice the diameter of the mixing pipe.

10. A desulfurization wastewater flue gas drying system with supplementary temperature as claimed in claim 9, characterized in that: The first mixing plate is provided with a plurality of vertically arranged ray strip holes with the center as the radiation center, and the distribution density of the ray strip holes on one side of the side channel is not more than 0.6 times the distribution density of the ray strip holes on the other side; The second mixing plate is provided with a plurality of annular channels arranged in an annular manner, each of the annular channels comprises a plurality of arc-shaped holes arranged at intervals, and the intervals between the annular channels are the same.

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