Devices and systems for denitrification in thermal power plants

Abstract

The invention discloses a device and a system for denitration in a thermal power plant, and relates to the technical field of denitration equipment; the device comprises a controller, a product gas input unit, a liquid ammonia input unit, a common input pipe, a steam input unit, a dilution fan, a heater, a warm air unit, a drain unit, a mixer, an electrically controlled three-way valve and a warm air branch; the product gas input unit is connected to the mixer via the common input pipe, the heater is connected to the mixer via the warm air unit, the controller is respectively connected to the product gas input unit, the liquid ammonia input unit, the steam input unit, the warm air unit and the drain unit, the liquid ammonia input unit is connected to the common input pipe via the electrically controlled three-way valve, the warm air unit is connected to the common input pipe via the warm air branch and the electrically controlled three-way valve, and the control end of the controller is connected to the control end of the electrically controlled three-way valve; a system for denitration in a thermal power plant is formed based on the device; and the pipeline is not easily blocked by crystals through the electrically controlled three-way valve and the warm air branch.

Description

Technical Field

[0001] The present invention relates to the technical field of denitration equipment, and in particular to a device and system for denitration in a thermal power plant. Background Art

[0002] At present, all domestic thermal power units are equipped with SCR denitration devices, and liquid ammonia is used as the denitration reducing agent. Due to the potential safety hazards in the transportation, storage and use of liquid ammonia, and the fact that the power plant sets up ammonia area with liquid ammonia storage tanks to store a certain amount of liquid ammonia, it is a major hazard source. Therefore, according to the requirements of current national and industry-related policies and regulations, in order to eliminate the transportation and storage safety risks of denitration reducing agents, power plants have begun to implement urea hydrolysis ammonia production process transformation to eliminate major hazard sources in the ammonia area. Urea hydrolysis ammonia production greatly reduces the liquid ammonia reserves of power plants, which is the source of the required liquid ammonia for the denitration device, while the small amount of liquid ammonia stored in the liquid ammonia storage tank is used as a backup source.

[0003] During the operation of the unit, after the hydrolyzer produces product gas, since it contains ammonia, it cannot be discharged into the atmosphere. It is transported to the unit's SCR ammonia injection system through the product gas pipeline. It is necessary to switch the existing unit's SCR from the liquid ammonia supply pipeline to the urea ammonia production pipeline. When the product gas quality is qualified, the SCR denitrification system is completely switched to urea product gas for ammonia supply; when the urea ammonia production system fails or needs maintenance, it is necessary to switch the urea hydrolysis product gas to the liquid ammonia storage tank for ammonia supply. Therefore, the operation mode of the SCR denitrification system needs to switch between three modes: liquid ammonia storage tank ammonia supply, urea product gas ammonia supply, and ammonia supply from both.

[0004] Existing technical problems and considerations:

[0005] How to solve the technical problem of easy crystallization and blockage in pipelines. Summary of the invention

[0006] The invention provides a device and a system for denitrification in a thermal power plant, which solve the technical problem of easy crystallization blockage in pipelines.

[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0008] A device for denitrification in a thermal power plant comprises a controller, a product gas input unit, a liquid ammonia input unit, a common input pipe, a steam input unit, a dilution fan, a heater, a warm air unit, a drain unit and a mixer. The product gas input unit is connected to the mixer via the common input pipe, the steam input unit and the dilution fan are respectively connected to the heater, the heater is connected to the mixer via the warm air unit, the heater is connected to the drain unit, the controller is respectively connected to the product gas input unit, the liquid ammonia input unit, the steam input unit, the warm air unit and the drain unit, and also comprises an electrically controlled three-way valve and a warm air branch. The liquid ammonia input unit is connected to the common input pipe via the electrically controlled three-way valve, the warm air unit is connected to the common input pipe via the warm air branch and the electrically controlled three-way valve, and the control end of the controller is connected to the control end of the electrically controlled three-way valve.

[0009] A further technical solution is that: the liquid ammonia input unit includes a liquid ammonia main line and a liquid ammonia electric-controlled valve arranged on the liquid ammonia main line, the warm air unit includes a warm air pipeline and a heater-side temperature sensor arranged on the warm air pipeline, the liquid ammonia main line is connected to the common input pipe via an electric-controlled three-way valve, the heater is connected to the mixer via the warm air pipeline, the warm air pipeline is connected to the common input pipe via a warm air branch and an electric-controlled three-way valve, the control end of the controller is connected to the control end of the liquid ammonia electric-controlled valve, and the heater-side temperature sensor is connected to and communicates with the controller.

[0010] A further technical solution is that: the product gas input unit includes a product gas main line and a product gas electric-controlled valve, the product gas main line is connected to the common input pipe, the product gas electric-controlled valve is arranged on the product gas main line, and the control end of the controller is connected to the control end of the product gas electric-controlled valve; the steam input unit includes a steam main line and a steam electric-controlled valve arranged on the steam main line, the steam main line is connected to the heater, and the control end of the controller is connected to the control end of the steam electric-controlled valve; the drain unit includes a drain main line and a drain electric door arranged on the drain main line, the drain main line is connected to the heater, and the control end of the controller is connected to the control end of the drain electric door.

[0011] A further technical solution is that the liquid ammonia input unit also includes an ammonia pressure sensor, which is arranged on the liquid ammonia main line between the liquid ammonia electric control valve and the electric control three-way valve, and the ammonia pressure sensor is connected to and communicates with the controller.

[0012] A further technical solution is that the product gas input unit also includes a product gas side temperature sensor and a product gas side pressure sensor, both of which are arranged on the product gas main line between the product gas electric control valve and the common input pipe, the product gas side temperature sensor is connected to and communicates with the controller, and the product gas side pressure sensor is connected to and communicates with the controller.

[0013] A further technical solution is that the liquid ammonia input unit also includes a liquid ammonia supply electric door, which is arranged on the liquid ammonia main line, and the control end of the controller is connected to the control end of the liquid ammonia supply electric door.

[0014] A further technical solution is that the product gas input unit also includes a product gas supply ammonia electric door, which is arranged on the product gas main line, and the control end of the controller is connected to the control end of the product gas supply ammonia electric door.

[0015] A further technical solution is that: the product gas input unit includes a product gas main line and a product gas bypass, the product gas main line is connected to the product gas bypass, and manual valves are provided on both the product gas main line and the product gas bypass; the liquid ammonia input unit includes a liquid ammonia main line and a liquid ammonia bypass, the liquid ammonia main line is connected to the liquid ammonia bypass, and manual valves are provided on both the liquid ammonia main line and the liquid ammonia bypass; the steam input unit includes a steam main line and a steam bypass, the steam main line is connected to the steam bypass, and manual valves are provided on both the steam main line and the steam bypass; the warm air unit includes a warm air pipeline, the heater is connected to the mixer via the warm air pipeline, and a manual valve is provided on the warm air pipeline; the drain unit includes a drain main line and a drain bypass, the drain main line is connected to the drain bypass, and manual valves are provided on both the drain main line and the drain bypass.

[0016] A further technical solution is that: the common input pipe is connected to the first input end of the mixer, the steam input unit is connected to the first input end of the air heater, the dilution fan is connected to the second input end of the air heater, the first output end of the air heater is connected to the second input end of the mixer via the warm air unit, and the second output end of the air heater is connected to the drain unit.

[0017] A system for denitration in a thermal power plant is provided, based on the above-mentioned device for denitration in a thermal power plant, to form a system for denitration in a thermal power plant.

[0018] The beneficial effects of adopting the above technical solution are:

[0019] First, a device for denitration in a thermal power plant includes a controller, a product gas input unit, a liquid ammonia input unit, a common input pipe, a steam input unit, a dilution fan, a heater, a warm air unit, a drain unit and a mixer. The product gas input unit is connected to the mixer via the common input pipe, the steam input unit and the dilution fan are respectively connected to the heater, the heater is connected to the mixer via the warm air unit, the heater is connected to the drain unit, the controller is respectively connected to the product gas input unit, the liquid ammonia input unit, the steam input unit, the warm air unit and the drain unit, and also includes an electrically controlled three-way valve and a warm air branch. The liquid ammonia input unit is connected to the common input pipe via the electrically controlled three-way valve, the warm air unit is connected to the common input pipe via the warm air branch and the electrically controlled three-way valve, and the control end of the controller is connected to the control end of the electrically controlled three-way valve. This technical solution makes it difficult for crystals to clog the pipeline through the electrically controlled three-way valve and the warm air branch.

[0020] Second, a system for denitration of thermal power plants is formed based on the above-mentioned device for denitration of thermal power plants. This technical solution uses an electrically controlled three-way valve and a warm air branch to prevent crystallization and blockage in the pipeline.

[0021] Please refer to the detailed description of the specific implementation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a distribution diagram of Example 1 of the present invention;

[0023] Figure 2 is a principle block diagram of embodiment 1 of the present invention;

[0024] Figure 3 is a distribution diagram of Example 2 of the present invention;

[0025] Figure 4 is a principle block diagram of embodiment 2 of the present invention;

[0026] Figure 5 is a distribution diagram of Example 3 of the present invention;

[0027] Figure 6 is a principle block diagram of embodiment 3 of the present invention;

[0028] Figure 7 is a distribution diagram of Example 4 of the present invention;

[0029] Figure 8 is a logic diagram of the present invention;

[0030] Fig. 9 It is a distribution diagram of the prior art solutions.

[0031] in:

[0032] 1. Product gas bypass manual door;

[0033] 2. The first manual door of the product gas main line;

[0034] 3. Second manual door of product gas main line;

[0035] 4. Electric door for product gas supply ammonia;

[0036] 5. Product gas supply ammonia adjustment valve;

[0037] 6 Liquid ammonia bypass manual door;

[0038] 7. The first manual door of the liquid ammonia main line;

[0039] 8. Electric door supplied with liquid ammonia;

[0040] 9Liquid ammonia supply and ammonia adjustment valve;

[0041] 10 The second manual door of the liquid ammonia main line;

[0042] 11. The first manual door of the steam main line;

[0043] 12. Second manual door of steam main line;

[0044] 13. Pneumatic regulating valve for steam pipeline;

[0045] 14 Steam bypass manual door;

[0046] 15 Manual door of induced draft duct;

[0047] 16 Manual door for warm air duct;

[0048] 17 The first manual door of the drainage main line;

[0049] 18. Second manual door of drain main line;

[0050] 19 Drain electric door;

[0051] 20 Drain bypass manual door;

[0052] 21 Product gas temperature transmitter;

[0053] 22 Product gas pressure transmitter;

[0054] 23 Ammonia pressure transmitter;

[0055] 24 warm air temperature transmitter;

[0056] 25 three-way valve;

[0057] 26 exit manual doors;

[0058] 27 easy to crystallize pipeline;

[0059] 28 Auxiliary temperature pipeline. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0061] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0062] Embodiment 1:

[0063] like Figure 1 and Figure 2 As shown, the present invention discloses a device for denitrification in a thermal power plant, including a controller, a product gas input unit, a liquid ammonia input unit, a common input pipe, a steam input unit, a dilution fan, a heater, a warm air unit, a drain unit, a mixer, an electrically controlled three-way valve and a warm air branch, wherein the electrically controlled three-way valve is a three-way valve 25, and the warm air branch is an auxiliary temperature pipeline 28.

[0064] like Figure 1 As shown, the product gas input unit is connected to the mixer via a common input pipe, the liquid ammonia input unit is connected to the common input pipe via an electrically controlled three-way valve, the steam input unit is connected to the heater, the dilution fan is connected to the heater, the heater is connected to the mixer via a warm air unit, the heater is connected to the drain unit, and the warm air unit is connected to the common input pipe via a warm air branch and an electrically controlled three-way valve.

[0065] like Figure 2 As shown, the control end of the controller is electrically connected to the control end of the product gas input unit, which is the control end of the product gas supply ammonia regulating valve 5; the control end of the controller is electrically connected to the control end of the liquid ammonia input unit, which is the control end of the liquid ammonia supply ammonia regulating valve 9; the control end of the controller is electrically connected to the control end of the steam input unit, which is the control end of the steam pipeline pneumatic regulating valve 13; the warm air unit is electrically connected to and communicates with the controller, that is, the warm air temperature transmitter 24 of the warm air unit is connected to the controller; the control end of the controller is electrically connected to the control end of the hydrophobic unit, which is the control end of the hydrophobic electric door 19; the control end of the controller is connected to the control end of the three-way valve 25.

[0066] Example 1 Instructions for use:

[0067] The control terminal is connected to the communication device of the controller and communicates with it, and the operator sends work instructions to the controller through the control terminal.

[0068] The operator controls the product gas input unit, the steam input unit and the drain unit as needed, so that the product gas and warm air are sent into the mixer. This working state is the product gas working state.

[0069] The operator controls the opening of the product gas supply ammonia regulating valve 5 according to needs to adjust the input amount of the product gas.

[0070] The operator controls the opening of the steam pipeline pneumatic regulating valve 13 as required to adjust the steam input.

[0071] The operator controls the warm air to be sent into the mixer through the three-way valve 25 according to the needs, and the pipeline between the three-way valve 25 and the mixer will not crystallize.

[0072] The operator controls the liquid ammonia supply regulating valve 9 and the three-way valve 25 as needed to feed liquid nitrogen into the mixer. This working state is the liquid ammonia working state.

[0073] The operator suspends the operation of the steam input unit and the drain unit as needed, and the air sent to the mixer does not need to be heated.

[0074] Embodiment 2:

[0075] like Figure 3 and Figure 4 As shown, the present invention discloses a device for denitrification in a thermal power plant, including a controller, a product gas input unit, a liquid ammonia input unit, a common input pipe, a steam input unit, a dilution fan, a heater, a warm air unit, a drain unit, a mixer, an electrically controlled three-way valve and a warm air branch, wherein the electrically controlled three-way valve is a three-way valve 25, and the warm air branch is an auxiliary temperature pipeline 28.

[0076] like Figure 3 As shown, the product gas input unit includes a product gas main line, a product gas electric-controlled valve, a product gas side temperature sensor and a product gas side pressure sensor. The product gas electric-controlled valve is the product gas ammonia supply regulating valve 5, the product gas side temperature sensor is the product gas temperature transmitter 21, and the product gas side pressure sensor is the product gas pressure transmitter 22. The product gas main line is connected to the first input end of the mixer via a common input pipe, the product gas electric-controlled valve is fixed on the product gas main line, and the product gas side temperature sensor and the product gas side pressure sensor are both fixed on the product gas main line between the product gas electric-controlled valve and the common input pipe.

[0077] like Figure 3As shown, the liquid ammonia input unit includes a liquid ammonia main line, a liquid ammonia electric-controlled valve and an ammonia pressure sensor. The liquid ammonia electric-controlled valve is the liquid ammonia supply regulating valve 9, and the ammonia pressure sensor is the ammonia pressure transmitter 23. The liquid ammonia electric-controlled valve is fixed on the liquid ammonia main line, and the liquid ammonia main line is connected to the common input pipe through an electric-controlled three-way valve. The ammonia pressure sensor is fixed on the liquid ammonia main line between the liquid ammonia electric-controlled valve and the electric-controlled three-way valve.

[0078] like Figure 3 As shown, the steam input unit includes a steam main line and a steam electric control valve fixed on the steam main line, the steam electric control valve is a steam line pneumatic regulating valve 13, and the steam main line is connected to the first input end of the heater.

[0079] like Figure 3 As shown, the dilution fan is connected to the second input end of the air heater.

[0080] like Figure 3 As shown, the warm air unit includes a warm air pipeline and a heater side temperature sensor fixed on the warm air pipeline, the heater side temperature sensor is the warm air temperature transmitter 24, the first output end of the heater is connected to the second input end of the mixer via the warm air pipeline, and the warm air pipeline is connected to the common input pipe via the warm air branch and the electric three-way valve.

[0081] like Figure 3 As shown, the drain unit includes a drain main line and a drain electric door 19 fixed on the drain main line, and the drain main line is connected to the second output end of the heater.

[0082] like Figure 4 As shown, the control end of the controller is electrically connected to the control end of the product gas input unit, which is the control end of the product gas electric-controlled valve, and the product gas electric-controlled valve is the product gas ammonia supply regulating valve 5; the control end of the controller is electrically connected to the control end of the liquid ammonia input unit, which is the control end of the liquid ammonia input unit, which is the control end of the liquid ammonia electric-controlled valve, and the liquid ammonia electric-controlled valve is the liquid ammonia supply ammonia regulating valve 9; the control end of the controller is electrically connected to the control end of the steam input unit, which is the control end of the steam electric-controlled valve, and the steam electric-controlled valve is the steam pipeline pneumatic regulating valve 13; the warm air unit is electrically connected to the controller and communicates, that is, the temperature sensor on the heater side is connected to the controller and communicates, and the temperature sensor on the heater side is the warm air temperature transmitter 24; the control end of the controller is electrically connected to the control end of the drain unit, which is the control end of the drain electric door 19; the control end of the controller is connected to the control end of the three-way valve 25.

[0083] like Figure 4As shown, the product gas side temperature sensor is connected and communicates with the controller, the product gas side pressure sensor is connected and communicates with the controller, and the ammonia pressure sensor is connected and communicates with the controller. The product gas side temperature sensor is a product gas temperature transmitter 21, the product gas side pressure sensor is a product gas pressure transmitter 22, and the ammonia pressure sensor is an ammonia pressure transmitter 23.

[0084] Example 2 Instructions for use:

[0085] The control terminal is connected to the communication device of the controller and communicates with each other. The operator sends the control logic to the controller in advance through the control terminal. The control method steps themselves are existing technologies and will not be repeated here.

[0086] The controller controls the product gas input unit, the steam input unit and the drain unit to operate as required, so that the product gas and warm air are sent into the mixer. This working state is the product gas working state.

[0087] The controller controls the opening of the product gas ammonia supply regulating valve 5 according to needs to adjust the input amount of the product gas.

[0088] The controller controls the opening of the steam pipeline pneumatic regulating valve 13 as required to adjust the steam input amount.

[0089] The controller controls the warm air to be sent into the mixer through the three-way valve 25 as required, and the pipeline between the three-way valve 25 and the mixer will not crystallize.

[0090] The controller controls the liquid ammonia supply regulating valve 9 and the three-way valve 25 as needed, so that liquid nitrogen is fed into the mixer. This working state is the liquid ammonia working state.

[0091] The controller suspends the operation of the steam input unit and the drain unit as needed, and the air sent to the mixer does not need to be heated.

[0092] Embodiment 3:

[0093] like Figure 5 and Figure 6 As shown, the present invention discloses a device for denitrification in a thermal power plant, including a controller, a product gas input unit, a liquid ammonia input unit, a common input pipe, a steam input unit, a dilution fan, a heater, a warm air unit, a drain unit, a mixer, an electrically controlled three-way valve and a warm air branch, wherein the electrically controlled three-way valve is a three-way valve 25, and the warm air branch is an auxiliary temperature pipeline 28.

[0094] like Figure 5As shown, the product gas input unit includes a product gas main line, a product gas ammonia supply electric door 4, a product gas electronically controlled valve, a product gas side temperature sensor and a product gas side pressure sensor, the product gas electronically controlled valve is the product gas ammonia supply regulating valve 5, the product gas side temperature sensor is the product gas temperature transmitter 21, the product gas side pressure sensor is the product gas pressure transmitter 22, the product gas main line is connected to the first input end of the mixer via a common input pipe, the product gas ammonia supply electric door 4 is fixed on the product gas main line, the product gas electronically controlled valve is fixed on the product gas main line, the product gas side temperature sensor and the product gas side pressure sensor are both fixed on the product gas main line between the product gas electronically controlled valve and the common input pipe.

[0095] like Figure 5 As shown, the liquid ammonia input unit includes a liquid ammonia main line, a liquid ammonia supply electric door 8, a liquid ammonia electronically controlled valve and an ammonia pressure sensor. The liquid ammonia electronically controlled valve is the liquid ammonia supply regulating valve 9, and the ammonia pressure sensor is the ammonia pressure transmitter 23. The liquid ammonia supply electric door 8 is fixed on the liquid ammonia main line, the liquid ammonia electronically controlled valve is fixed on the liquid ammonia main line, the liquid ammonia main line is connected to the common input pipe via an electronically controlled three-way valve, and the ammonia pressure sensor is fixed on the liquid ammonia main line between the liquid ammonia electronically controlled valve and the electronically controlled three-way valve.

[0096] like Figure 5 As shown, the steam input unit includes a steam main line and a steam electric control valve fixed on the steam main line, the steam electric control valve is a steam line pneumatic regulating valve 13, and the steam main line is connected to the first input end of the heater.

[0097] like Figure 5 As shown, the dilution fan is connected to the second input end of the air heater.

[0098] like Figure 5 As shown, the warm air unit includes a warm air pipeline and a heater side temperature sensor fixed on the warm air pipeline, the heater side temperature sensor is the warm air temperature transmitter 24, the first output end of the heater is connected to the second input end of the mixer via the warm air pipeline, and the warm air pipeline is connected to the common input pipe via the warm air branch and the electric three-way valve.

[0099] like Figure 5 As shown, the drain unit includes a drain main line and a drain electric door 19 fixed on the drain main line, and the drain main line is connected to the second output end of the heater.

[0100] like Figure 6As shown, the control end of the controller is electrically connected to the control end of the product gas input unit, which is the control end of the product gas electric-controlled valve, and the product gas electric-controlled valve is the product gas ammonia supply regulating valve 5; the control end of the controller is electrically connected to the control end of the liquid ammonia input unit, which is the control end of the liquid ammonia input unit, which is the control end of the liquid ammonia electric-controlled valve, and the liquid ammonia electric-controlled valve is the liquid ammonia supply ammonia regulating valve 9; the control end of the controller is electrically connected to the control end of the steam input unit, which is the control end of the steam electric-controlled valve, and the steam electric-controlled valve is the steam pipeline pneumatic regulating valve 13; the warm air unit is electrically connected to the controller and communicates, that is, the temperature sensor on the heater side is connected to the controller and communicates, and the temperature sensor on the heater side is the warm air temperature transmitter 24; the control end of the controller is electrically connected to the control end of the drain unit, which is the control end of the drain electric door 19; the control end of the controller is connected to the control end of the three-way valve 25.

[0101] like Figure 6 As shown, the product gas side temperature sensor is connected and communicates with the controller, the product gas side pressure sensor is connected and communicates with the controller, and the ammonia pressure sensor is connected and communicates with the controller. The product gas side temperature sensor is a product gas temperature transmitter 21, the product gas side pressure sensor is a product gas pressure transmitter 22, and the ammonia pressure sensor is an ammonia pressure transmitter 23.

[0102] like Figure 6 As shown, the control end of the controller is connected to the control end of the product gas supply ammonia electric door 4, and the control end of the controller is connected to the control end of the liquid ammonia supply ammonia electric door 8.

[0103] Embodiment 4:

[0104] like Figure 7 As shown, the present invention discloses a device for denitration in a thermal power plant, which is further improved as follows based on Example 3:

[0105] The product gas input unit also includes a product gas bypass, the product gas main line is connected to the product gas bypass, and manual valves are installed on the product gas main line and the product gas bypass. The manual valve includes a product gas bypass manual door 1, a product gas main line first manual door 2, a product gas main line second manual door 3 and an outlet manual door 26, the product gas bypass manual door 1 is fixedly connected to the product gas bypass, the product gas main line first manual door 2, the product gas ammonia supply electric door 4, the product gas ammonia supply regulating valve 5, the product gas main line second manual door 3, the product gas temperature transmitter 21, the product gas pressure transmitter 22 and the outlet manual door 26 are fixedly connected to the product gas main line in sequence.

[0106] The liquid ammonia input unit also includes a liquid ammonia bypass, the liquid ammonia main line is connected to the liquid ammonia bypass, and manual valves are installed on the liquid ammonia main line and the liquid ammonia bypass. The manual valve includes a liquid ammonia bypass manual door 6, a liquid ammonia main line first manual door 7 and a liquid ammonia main line second manual door 10, the liquid ammonia bypass manual door 6 is fixedly connected to the liquid ammonia bypass, the liquid ammonia main line first manual door 7, the liquid ammonia supply electric door 8, the liquid ammonia supply ammonia regulating valve 9, the liquid ammonia main line second manual door 10, the ammonia pressure transmitter 23 and the three-way valve 25 are fixedly connected to the liquid ammonia main line in sequence.

[0107] The steam input unit further includes a steam bypass, the steam main line is connected to the steam bypass, and manual valves are installed on the steam main line and the steam bypass. The manual valves include a first manual door 11 of the steam main line, a second manual door 12 of the steam main line, and a steam bypass manual door 14, the steam bypass manual door 14 is fixedly connected to the steam bypass, and the first manual door 11 of the steam main line, the steam pipeline pneumatic regulating valve 13, and the second manual door 12 of the steam main line are fixedly connected to the steam main line in sequence.

[0108] It also includes a manual door 15 for the induced air duct, and the dilution fan is connected to the heater via the manual door 15 for the induced air duct.

[0109] A manual valve, namely a manual door 16 for the warm air pipeline is installed on the warm air pipeline. The manual door 16 for the warm air pipeline and the warm air temperature transmitter 24 are fixedly connected to the warm air pipeline in sequence.

[0110] The drain unit also includes a drain bypass, the drain main line is connected to the drain bypass, and manual valves are installed on the drain main line and the drain bypass. The manual valve includes a first manual door 17 of the drain main line, a second manual door 18 of the drain main line, and a manual door 20 of the drain bypass. The manual door 20 of the drain bypass is fixedly connected to the drain bypass, and the first manual door 17 of the drain main line, the drain electric door 19, and the second manual door 18 of the drain main line are fixedly connected to the drain main line in sequence.

[0111] Embodiment 5:

[0112] The present invention discloses a device for denitration in a thermal power plant. Based on Example 1, the device is further improved as follows:

[0113] The product gas input unit also includes a product gas bypass, the product gas main line is connected to the product gas bypass, and manual valves are installed on both the product gas main line and the product gas bypass. The liquid ammonia input unit also includes a liquid ammonia bypass, the liquid ammonia main line is connected to the liquid ammonia bypass, and manual valves are installed on both the liquid ammonia main line and the liquid ammonia bypass. The steam input unit also includes a steam bypass, the steam main line is connected to the steam bypass, and manual valves are installed on both the steam main line and the steam bypass. A manual valve is installed on the warm air pipeline. The drain unit also includes a drain bypass, the drain main line is connected to the drain bypass, and manual valves are installed on both the drain main line and the drain bypass. The similarities are not repeated here. Bypass and manual doors are installed to facilitate repair and maintenance.

[0114] Compared with the above embodiment, a control end of a controller and a dilution fan may also be used to control the dilution fan as required.

[0115] Embodiment 6:

[0116] The present invention discloses a system for denitrification in a thermal power plant, comprising the device of embodiment 1, and further comprising a urea product gas generating device, a liquid ammonia storage tank, a steam generating device and an ammonia injection grid, wherein the urea product gas generating device is connected to a product gas main line, the liquid ammonia storage tank is connected to a liquid ammonia main line, the steam generating device is connected to a steam main line, and an output end of a mixer is connected to the ammonia injection grid.

[0117] With respect to the above-mentioned embodiments, a device for denitrification of a thermal power plant based on any one of Embodiments 2 to 5 may also be used, which further includes a urea product gas generating device, a liquid ammonia storage tank, a steam generating device and an ammonia injection grid to form a system for denitrification of a thermal power plant, and similarities are not repeated here.

[0118] Development process:

[0119] The inventor believes that the invention has the following points:

[0120] 1. Online automatic switching technology for urea product gas and liquid ammonia storage tank supply in the denitration system of thermal power plants. The realization of online automatic switching technology can effectively improve the automation level of the unit's denitration device, greatly reduce the risk of environmental protection exceeding the standard during the online switching of the liquid ammonia source of the operating unit, effectively reduce the workload of operators, and reduce human errors. If the liquid ammonia source of the denitration system can be automatically switched with one button, it will effectively improve the environmental protection and safety of the operation of thermal power units.

[0121] 2. Technology to prevent blockage of liquid ammonia supply pipeline. After the denitrification system switches to urea product gas, the pipeline behind the manual door of the product gas outlet is connected to the pipeline behind the manual door of the liquid ammonia outlet, and the product gas enters the pipeline behind the manual door of the liquid ammonia outlet. Due to the low temperature, the product gas crystallizes there, which will cause blockage of the liquid ammonia pipeline for a long time, and the liquid ammonia supply pipeline loses its backup function. When the urea product gas fails to supply gas, the liquid ammonia pipeline cannot supply gas normally due to blockage after switching, causing the hourly average value of nitrogen oxides NOx to exceed the standard, which poses a great risk of exceeding environmental standards. This improved technical solution replaces the manual door of the liquid ammonia outlet with a three-way valve. When liquid ammonia is supplied, the liquid ammonia supply pipeline is connected, and the dilution air enters the mixer directly without passing through the three-way valve; when the product gas is supplied, the liquid ammonia supply pipeline is blocked, and part of the high-temperature air from the dilution fan enters the mixer through the three-way valve, thereby preventing blockage of the ammonia supply pipeline.

[0122] 1. The most basic technical problems to be solved

[0123] like Fig. 9 As shown, the output end of the product gas input unit is connected to the output end of the liquid ammonia input unit and then connected to the first input end of the mixer via a common input pipe.

[0124] At present, the switching process of the system completely relies on manual switching. If the control is not done properly, the NOx emission value may fluctuate greatly, and there is a risk that the hourly average NOx emission value may exceed the environmental protection standard, which seriously affects the environmental protection safety of the unit. At the same time, due to the existence of two ammonia sources, urea product gas is easy to crystallize in a low temperature environment. In the area where the liquid ammonia pipeline and the product gas are the same, the crystallization pipeline is prone to blockage at 27 points. When the urea product gas system fails to supply gas, the liquid ammonia pipeline loses its backup and causes the hourly average NOx value to exceed the standard, which also affects the environmental protection safety of the unit.

[0125] 2. Core Technology Solution

[0126] Improvements:

[0127] The online automatic switching technology between the urea product gas and the liquid ammonia storage tank ammonia supply in the denitrification system realizes the online automatic switching between liquid ammonia and urea product gas, reducing the risk of manual operation; the modification of the manual door at the outlet of the liquid ammonia supply pipeline effectively suppresses the crystallization of the product gas, prevents the blockage of the pipeline, and reduces the risk of exceeding environmental protection standards.

[0128] Online automatic switching module:

[0129] 1. Check function:

[0130] Check that the product gas pipeline has been purged, the three-way valve of the liquid ammonia pipeline has been switched back to the main pipeline, and the switching conditions have been met.

[0131] 2. Switching function:

[0132] Before switching, either the urea ammonia supply regulating valve or the liquid ammonia supply regulating valve is at a certain opening, and the other is at a closed position. When switching, the switching module receives pipeline pressure signals from both.

[0133] like Figure 8 As shown, after the automatic switching command is issued, the liquid ammonia supply valve and the urea product gas supply valve 5 automatically operate according to the function logic. When the pressure of the pipeline on the side that needs to be opened reaches 0.35Mpa, the ammonia supply pipeline valve on the original operating side automatically operates according to the corresponding side function logic until it is completely closed, and the switching command stops. The opening of the current operating side valve follows the NOx outlet set value according to environmental protection requirements. During this period, pay attention to the NOx concentration at the boiler SCR outlet and the NOx concentration at the chimney inlet.

[0134] During the switching process, ensure that the NOx emission concentration of nitrogen oxides at the chimney outlet meets the environmental protection indicators. If the NOx concentration fluctuates greatly, the primary task is to ensure that the environmental protection indicators are met. If necessary, the pipeline switching can be suspended and the switching can be continued after the emission indicators stabilize.

[0135] Equipment working process description:

[0136] See Table 1, which is a function logic table.

[0137] Table 1: Function logic table

[0138]

[0139] like Figure 8 As shown in Table 1, an example of the logic of the function in the figure.

[0140] Generally, in the denitrification system of a thermal power plant, ammonia is used as a reducing agent to eliminate nitrogen oxides in the flue gas to achieve the purpose of denitrification. The sources of ammonia are divided into two routes, namely, ammonia of a certain concentration produced by the thermal decomposition of urea solution, which are called product gas and liquid ammonia respectively. Normal operation can be carried out by only one route, and switching between the two is required when necessary.

[0141] 1. Switch from liquid ammonia to urea product gas

[0142] like Figure 7 As shown, since urea product gas is easy to crystallize, a steam tracing system needs to be put into operation before the urea ammonia supply pipeline is put into operation to ensure that the temperature of the product gas transported by the pipeline reaches 130°C, which is transmitted to the controller by the product gas temperature transmitter 21. Before the product gas pipeline is put into operation, it needs to be purged with steam, and the first manual door 2 of the product gas main pipeline, the second manual door 3 of the product gas main pipeline, the product gas ammonia supply electric door 4, and the product gas ammonia supply regulating valve 5 are kept closed. The product gas ammonia supply main pipe is pressurized to 0.15MPa with steam, and the product gas bypass manual door 1 is opened. After purging the product gas pipeline with steam for 30 minutes, a notice of purging is given, and the product gas bypass manual door 1 is closed.

[0143] like Figure 7 As shown, the dilution fan supplies dilution air, which is fully mixed with ammonia in the ammonia-air mixer to dilute the ammonia to a concentration of less than 5%. When liquid ammonia is running, there is no need to heat the dilution air. When liquid ammonia is supplying ammonia, all valves of the steam pipeline and the drain pipeline are closed. Before switching from liquid ammonia supply to urea supply, in order to prevent the crystallization of urea product gas, it is necessary to open the first manual door 11 of the steam main line and the second manual door 12 of the steam main line in advance, open the first manual door 17 of the drain main line and the second manual door 18 of the drain main line, open the drain electric door 19, manually open the first manual door 2 of the product gas main line and the second manual door 3 of the product gas main line, and open the ammonia supply electric door 4.

[0144] like Figure 7 As shown, after the hydrolyzer operating parameters reach the ammonia supply conditions, the switching command is executed, the steam pipeline pneumatic regulating valve 13 is slowly opened, and the dilution air temperature is adjusted to 140° C., which is transmitted to the controller by the warm air temperature transmitter 24 .

[0145] like Figure 8 As shown, the product gas supply ammonia regulating valve 5 is slowly opened according to the regulating valve action logic of F1(x)-F5(x) in the figure, and when the product gas pipeline pressure reaches 0.35Mpa, the pressure is transmitted to the controller by the product gas pressure transmitter 22, and the liquid ammonia supply ammonia regulating valve 9 is opened according to F6(x)-F 10 (x) The valve action logic is closed slowly. When all the liquid ammonia supply valves are closed, the three-way valve 25 is switched from the liquid ammonia side to the hot air side, the switching instruction is terminated, and the switching is completed. Close the liquid ammonia supply valve 9, close the first manual door 7 of the liquid ammonia main line, and close the second manual door 10 of the liquid ammonia main line.

[0146] like Figure 7 As shown, in the mode of ammonia supply by urea product gas, the easy-to-crystallize pipeline is connected to the product gas pipeline. There is no heating in this area. The product gas gathered here will produce crystals after cooling. For a long time, this part of the pipeline will be blocked by crystals, making the liquid ammonia pipeline lose its backup, which will lay hidden dangers for future switching. Therefore, in the mode of ammonia supply by product gas, the three-way valve 25 needs to be turned to the hot air side. At this time, the ammonia supply system of the unit is switched from the liquid ammonia supply system to the urea ammonia supply system.

[0147] 2. Switching from urea product gas to liquid ammonia

[0148] like Figure 7 As shown, the first manual door 7 of the liquid ammonia main line, the second manual door 10 of the liquid ammonia main line, and the electric door 9 for liquid ammonia supply execute the automatic switching instruction to switch the three-way valve 25 from the hot air side to the liquid ammonia side. The liquid ammonia supply regulating door 9 follows F6(x)-F 10(x) The valve action logic opens slowly. When the pressure of the liquid ammonia supply pipeline reaches 0.35Mpa, the pressure is transmitted to the controller by the ammonia pressure transmitter 23. The product gas supply ammonia valve 5 closes slowly according to the F1(x)-F5(x) valve action logic. When the product gas supply ammonia valve 5 is completely closed, the steam pipeline pneumatic valve 13 closes automatically. After confirming that there is no drainage, the drainage electric door 19 is closed, and the switching is terminated.

[0149] like Figure 8 As shown in the figure, F1(x)-F5(x) are the logic functions of the urea ammonia supply valve action, F6(x)-F 10 (x) is the logic function of the liquid ammonia supply valve action, Σ is the adder, and T is the feedback device.

[0150] As shown in Table 1, the logical interpretation is:

[0151] Taking the F1(x)-F5(x) function as an example, when the instruction input is 0, the valve opening output is 0; when the instruction input is 7, the valve opening output is 9; when the instruction input is 27, the valve opening output is 20; when the instruction input is 35, the valve opening output is 31; when the instruction input is 56, and so on, when the instruction input is 69, the valve opening output is 61; when the instruction input is 75, the valve opening output is 69; when the instruction input is 100, the valve opening output is 100.

[0152] That is, when the input command is 0-27, the valve opening corresponds to 0-20; when the input command is 27-56, the valve opening corresponds to 20-45; when the input command is 56-69, the valve opening corresponds to 45-61; when the input command is 69-75, the valve opening corresponds to 61-69; when the input command is 75-100, the valve opening corresponds to 69-100. The input command receives the outlet pressure signal of the ammonia supply pipeline. The pressure on the side where the valve needs to be opened is set to 0.35. This parameter can be changed. When the pressure is less than 0.35Mpa, the command gradually increases; when the pressure is equal to 0.35Mpa, the command is maintained; when the pressure is greater than 0.35Mpa, the command gradually closes.

[0153] The pressure on the side where the throttle needs to be closed is set to 0, and the throttle needs to be closed gradually. When the throttle opening is ≤20, the command is output in sequence according to the throttle opening: 27, 22, 18, 14, 7, 0; when the throttle opening is ≤45, the command is output in sequence according to the throttle opening: 56, 47, 42, 35, 27, 22, 18, 14, 7, 0; when the throttle opening is ≤61, the command is output in sequence according to the throttle opening: 69, 68, 67, 65, 60, 56, 47, 42, 35, 27, 22, 18, 14, 7, 0; when the throttle opening is ≤69, the command is output in sequence according to the throttle opening: The outputs are 75, 73, 72, 71, 70, 69, 68, 67, 65, 60, 56, 47, 42, 35, 27, 22, 18, 14, 7, 0 according to the valve opening. When the valve opening is ≤100, the outputs are 100, 95, 87, 81, 77, 75, 73, 72, 71, 70, 69, 68, 67, 65, 60, 56, 47, 42, 35, 27, 22, 18, 14, 7, 0 according to the valve opening.

[0154] Technical contributions of this application:

[0155] After communicating with the inventor, the project team believed that the technical contribution of this project lies in the combination of the conversion device formed by the addition of the three-way valve, which is essentially different from the existing technical solutions and is not easy to think of.

[0156] After this application was run internally for a period of time, the on-site technicians reported that the application was beneficial in the following ways:

[0157] The technical solution in this improvement project is used for the online automatic switching of urea product gas and liquid ammonia storage tank supply in the denitration system of thermal power plants. The realization of automatic switching technology can effectively reduce manual operation, reduce the workload of personnel, reduce human error, and improve the safety factor of the operating unit. The anti-blocking transformation of the pipeline ensures the reliable backup of the liquid ammonia pipeline and effectively reduces the possibility of environmental protection exceeding the standard in the event of a urea product gas system failure.

[0158] At present, the technical solution of the present invention has been put into pilot production, that is, a small-scale test of the product before large-scale mass production; after the pilot production was completed, a user usage survey was carried out in a small range, and the survey results showed that user satisfaction was high; now preparations have begun for the formal production of the product for industrialization (including intellectual property risk warning survey).

Claims

1. A device for denitration in a thermal power plant, comprising a controller, a product gas input unit, a liquid ammonia input unit, a common input pipe, a steam input unit, a dilution fan, a heater, a warm air unit, a drain unit and a mixer, wherein the product gas input unit is connected to the mixer via the common input pipe, the steam input unit and the dilution fan are respectively connected to the heater, the heater is connected to the mixer via the warm air unit, the heater is connected to the drain unit, the controller is respectively connected to the product gas input unit, the liquid ammonia input unit, the steam input unit, the warm air unit and the drain unit, and characterized in that: It also includes an electrically controlled three-way valve and a warm air branch. The liquid ammonia input unit is connected to the common input pipe through the electrically controlled three-way valve, and the warm air unit is connected to the common input pipe through the warm air branch and the electrically controlled three-way valve. The control end of the controller is connected to the control end of the electrically controlled three-way valve. The liquid ammonia input unit includes a liquid ammonia main line and a liquid ammonia electrically controlled valve arranged on the liquid ammonia main line. The warm air unit includes a warm air pipeline and a heater-side temperature sensor arranged on the warm air pipeline. The liquid ammonia main line is connected to the common input pipe through the electrically controlled three-way valve, the heater is connected to the mixer through the warm air pipeline, the warm air pipeline is connected to the common input pipe through the warm air branch and the electrically controlled three-way valve, and the control end of the controller is connected to the control end of the liquid ammonia electrically controlled valve. The temperature sensor on the heater side is connected and communicates with the controller; the product gas input unit includes a product gas main line and a product gas electric-controlled valve, the product gas main line is connected to the common input pipe, the product gas electric-controlled valve is arranged on the product gas main line, and the control end of the controller is connected to the control end of the product gas electric-controlled valve; the steam input unit includes a steam main line and a steam electric-controlled valve arranged on the steam main line, the steam main line is connected to the heater, and the control end of the controller is connected to the control end of the steam electric-controlled valve; the drain unit includes a drain main line and a drain electric door arranged on the drain main line, the drain main line is connected to the heater, and the control end of the controller is connected to the control end of the drain electric door.

2. The device for denitrification in thermal power plants according to claim 1, characterized in that: The liquid ammonia input unit also includes an ammonia pressure sensor, which is arranged on the liquid ammonia main line between the liquid ammonia electric control valve and the electric control three-way valve, and is connected to and communicates with the controller.

3. The device for denitrification in thermal power plants according to claim 1, characterized in that: The product gas input unit also includes a product gas side temperature sensor and a product gas side pressure sensor. The product gas side temperature sensor and the product gas side pressure sensor are both arranged on the product gas main line between the product gas electric control valve and the common input pipe. The product gas side temperature sensor is connected to and communicates with the controller, and the product gas side pressure sensor is connected to and communicates with the controller.

4. The device for denitrification in thermal power plants according to claim 1, characterized in that: The liquid ammonia input unit also includes a liquid ammonia supply electric door, which is arranged on the liquid ammonia main line, and the control end of the controller is connected to the control end of the liquid ammonia supply electric door.

5. The device for denitrification in thermal power plants according to claim 1, characterized in that: The product gas input unit also includes a product gas ammonia supply electric door, which is arranged on the product gas main line, and the control end of the controller is connected to the control end of the product gas ammonia supply electric door.

6. The device for denitrification in thermal power plants according to claim 1, characterized in that: The product gas input unit includes a product gas main line and a product gas bypass, the product gas main line is connected to the product gas bypass, and manual valves are provided on both the product gas main line and the product gas bypass; the liquid ammonia input unit includes a liquid ammonia main line and a liquid ammonia bypass, the liquid ammonia main line is connected to the liquid ammonia bypass, and manual valves are provided on both the liquid ammonia main line and the liquid ammonia bypass; the steam input unit includes a steam main line and a steam bypass, the steam main line is connected to the steam bypass, and manual valves are provided on both the steam main line and the steam bypass; the warm air unit includes a warm air pipeline, the heater is connected to the mixer via the warm air pipeline, and a manual valve is provided on the warm air pipeline; the drain unit includes a drain main line and a drain bypass, the drain main line is connected to the drain bypass, and manual valves are provided on both the drain main line and the drain bypass.

7. The device for denitrification in thermal power plants according to claim 1, characterized in that: The common input pipe is connected to the first input end of the mixer, the steam input unit is connected to the first input end of the air heater, the dilution fan is connected to the second input end of the air heater, the first output end of the air heater is connected to the second input end of the mixer via the warm air unit, and the second output end of the air heater is connected to the drain unit.

8. A system for denitrification in a thermal power plant, characterized in that: Based on the device for denitration in a thermal power plant as described in any one of claims 1 to 7, a system for denitration in a thermal power plant is formed.

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