Ammonia water evaporation system for flue gas denitration

Abstract

The utility model discloses flue gas denitration ammonia water evaporation system, including boiler primary air pipeline, electric heater and evaporimeter, and the air inlet of electric heater is linked together with boiler primary air pipeline through first air inlet pipeline, and the air outlet of electric heater is linked together with the air inlet of evaporimeter through second air inlet pipeline, and the inside lower extreme of evaporimeter is installed with the spray gun for spraying ammonia water to the inside of evaporimeter, and the top of evaporimeter is linked with ammonia gas air outlet pipeline, and the utility model discloses through boiler primary air pipeline introduction by the primary air of high temperature flue gas of boiler combustion through air preheater heating, then combining electric heater carries out supplementary heating to it, has realized to the reasonable utilization of energy, has reduced energy waste, and primary air has certain heat, can satisfy ammonia water evaporation demand after proper heating through electric heater, has avoided simply using high energy consumption heating mode, has improved energy utilization efficiency.

Description

Technical Field

[0001] This utility model relates to the field of flue gas denitrification technology, and in particular to an ammonia water evaporation system for flue gas denitrification. Background Technology

[0002] In the flue gas denitrification process, the ammonia evaporation system is a key piece of equipment that evaporates ammonia water into ammonia gas, mixes it with air, and then sends it into the denitrification reactor.

[0003] Chinese utility model patent CN211586033U discloses a boiler flue gas denitrification device, including an ammonia water tank. The device further includes an ammonia water tank; the ammonia water tank is connected to an ammonia water spray gun in the furnace through a first ammonia water pipeline; the top of the furnace is connected to the top of a catalytic reactor through a flue gas pipeline; the ammonia water tank is also connected to the upper part of an ammonia water evaporator through a second ammonia water pipeline; the top of the ammonia water evaporator is connected to a distributor installed in the catalytic reactor; and the lower part of the ammonia water evaporator is connected to a dilution fan.

[0004] The aforementioned flue gas denitrification device uses a hot air blower to heat the air before blowing it into the ammonia evaporator when evaporating ammonia water, resulting in high energy consumption. Utility Model Content

[0005] The purpose of this invention is to provide an ammonia water evaporation system for flue gas denitrification, in order to solve the technical problem of high energy consumption caused by the use of a hot air blower for heating ammonia water in existing devices.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] Ammonia water evaporation system for flue gas denitrification includes:

[0008] The primary air duct of the boiler is formed by heating the high-temperature flue gas generated by boiler combustion through an air preheater.

[0009] An electric heater, the air inlet of which is connected to the primary air duct of the boiler via a first air inlet duct;

[0010] The outlet of the electric heater is connected to the inlet of the evaporator through a second air inlet pipe. A spray gun for spraying ammonia water into the evaporator is installed at the lower end of the evaporator. An ammonia gas outlet pipe is connected to the top of the evaporator.

[0011] As a preferred embodiment of this utility model, a valve is installed on the first air inlet duct.

[0012] As a preferred embodiment of this utility model, a first pressure indicator for monitoring the pressure of the first air inlet duct and a first temperature indicator for monitoring the temperature of the air inside the duct are respectively installed on the first air inlet duct.

[0013] As a preferred embodiment of this utility model, a second temperature indicator is installed on the second air inlet duct for monitoring the air temperature inside the second air inlet duct.

[0014] As a further preferred embodiment of this utility model, the system also includes a DCS control system, a first temperature sensor and a flow indicator transmitter are installed on the second air inlet duct, a second temperature sensor is installed on the evaporator, the first temperature sensor, the flow indicator transmitter and the second temperature sensor are all electrically connected to the DCS control system, the valve is an electric regulating valve, and the valve, electric heater and spray gun are all controlled by the DCS control system.

[0015] As a preferred embodiment of this utility model, the evaporator is equipped with a second pressure gauge for monitoring its internal pressure and a third temperature gauge for monitoring its internal temperature.

[0016] As a preferred embodiment of this utility model, the second air inlet pipe is a carbon steel pipe, and the outer wall of the second air inlet pipe is wrapped with a first insulation layer.

[0017] As a preferred embodiment of this utility model, the ammonia gas outlet pipe is a 304 stainless steel pipe, and the outer wall of the ammonia gas outlet pipe is wrapped with a second insulation layer.

[0018] Compared with existing technologies, the ammonia evaporation system for flue gas denitrification provided by this utility model has the following advantages:

[0019] This invention introduces primary air heated by the high-temperature flue gas from boiler combustion through the boiler's primary air duct, and then uses an electric heater for auxiliary heating. This achieves rational use of energy and reduces energy waste. The primary air itself contains a certain amount of heat, which, after being properly heated by the electric heater, can meet the requirements for ammonia evaporation. This avoids the use of high-energy-consuming heating methods and improves energy efficiency.

[0020] The system is equipped with multiple pressure and temperature gauges, along with temperature sensors and flow transmitters. It also uses a DCS control system to intelligently control valves, electric heaters, and spray guns, enabling precise monitoring and regulation of parameters such as pressure, temperature, and flow within the system, thus ensuring stable and efficient operation. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only examples of embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1This is a structural schematic diagram of an embodiment of the present utility model.

[0023] Figure label:

[0024] 1. Boiler primary air duct; 101. First air inlet duct; 102. Butterfly valve; 103. First temperature indicator; 104. First pressure indicator;

[0025] 2. Electric heater; 201. Second air inlet duct; 202. Second temperature indicator; 203. First temperature sensor; 204. Flow indicator transmitter;

[0026] 3. Evaporator; 301. Second pressure gauge; 302. Third temperature gauge; 303. Second temperature sensor; 304. Ammonia gas outlet duct;

[0027] 4. Spray gun;

[0028] 5. DCS control system. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0030] In the description of the embodiments of the present invention, it should be understood that the terms "upper", "lower", "front", "rear", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention.

[0031] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an integral connection, or a detachable connection; they can refer to the internal connection of two components; they can refer to a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present invention should be understood according to the specific circumstances.

[0032] See Figure 1 As shown, the ammonia water evaporation system for flue gas denitrification in this embodiment of the present invention includes a boiler primary air duct 1, an electric heater 2, and an evaporator 3;

[0033] The primary air in the boiler primary air duct 1 is formed by heating the high-temperature flue gas generated by boiler combustion through an air preheater. During operation, the high-temperature flue gas exchanges heat with cold air in the air preheater, heating the cold air into primary air with a certain temperature. The primary air flows in the boiler primary air duct 1, providing a heat source for the subsequent evaporation of ammonia water.

[0034] The air inlet of the electric heater 2 is connected to the boiler primary air duct 1 via the first air inlet duct 101. When primary air from the boiler primary air duct 1 enters the first air inlet duct 101, it flows into the electric heater 2. The function of the electric heater 2 is to provide additional heating to the primary air when necessary, ensuring that the temperature of the hot air entering the evaporator 3 meets the requirements for ammonia evaporation. For example, when the initial temperature of the boiler primary air is insufficient for efficient ammonia evaporation, the electric heater 2 is activated, converting electrical energy into heat energy to increase the temperature of the primary air.

[0035] The outlet of the electric heater 2 is connected to the inlet of the evaporator 3 via the second air inlet pipe 201. A spray gun for spraying ammonia water into the evaporator 3 is installed at the lower end of the evaporator 3, and an ammonia gas outlet pipe 304 connects to the top of the evaporator 3. Hot air heated by the electric heater 2 enters the evaporator 3 through the second air inlet pipe 201. Simultaneously, ammonia water is sprayed into the evaporator 3 through the spray gun. The heat from the hot air is transferred to the ammonia water, causing it to absorb heat and gradually evaporate. The resulting mixture of ammonia gas and incompletely evaporated ammonia water vapor is discharged from the ammonia gas outlet pipe 304 at the top of the evaporator 3, entering the subsequent denitrification reaction stage.

[0036] A valve 102 is installed on the first air inlet duct 101. The function of valve 102 is to control the flow rate of primary air in the first air inlet duct 101. When it is necessary to adjust the primary air volume entering the electric heater 2, thereby regulating the temperature and flow rate of the hot air finally entering the evaporator 3, this can be achieved by operating valve 102. When the ammonia evaporation effect in the evaporator 3 is poor and the hot air volume needs to be increased, valve 102 can be opened wider; conversely, when the temperature in the evaporator 3 is too high and the hot air volume needs to be reduced, valve 102 can be closed narrowly.

[0037] The first air inlet duct 101 is equipped with a first pressure indicator 104 for monitoring the duct pressure and a first temperature indicator 103 for monitoring the internal air temperature. The first pressure indicator 104 displays the pressure value of the primary air in the first air inlet duct 101 in real time. Operators can use this pressure value to determine whether the airflow pressure in the duct is normal and whether there are any abnormalities such as blockages. A sudden increase in pressure may indicate a blockage in the duct, causing poor airflow; a low pressure indicates that equipment such as the fan is malfunctioning and failing to provide sufficient air pressure. The first temperature indicator 103 monitors the temperature of the primary air in the first air inlet duct 101 in real time, allowing operators to understand the initial temperature of the primary air before it enters the electric heater 2. This information, combined with the evaporation requirements of the subsequent evaporator 3, allows for a comprehensive judgment on whether the electric heater 2 needs to be turned on or adjusted.

[0038] A second temperature indicator 202 is installed on the second air inlet duct 201 to monitor the air temperature inside the duct. The second temperature indicator 202 displays the real-time temperature of the hot air before it enters the evaporator 3 after being heated by the electric heater 2. By observing this temperature value, operators can intuitively understand the actual temperature of the hot air entering the evaporator 3. This helps them determine whether the heating effect of the electric heater 2 meets the requirements, and adjust the heating power of the electric heater 2 or the opening of the valve 102 on the first air inlet duct 101 in a timely manner according to the evaporation status of the ammonia in the evaporator 3, to ensure that the temperature of the hot air entering the evaporator 3 meets the conditions for efficient ammonia evaporation.

[0039] In this embodiment of the utility model, the ammonia water evaporation system for flue gas denitrification also includes a DCS control system 5. A first temperature sensor 203 and a flow indicator transmitter 204 are installed on the second air inlet duct 201, and a second temperature sensor 303 is installed on the evaporator 3. The first temperature sensor 203, the flow indicator transmitter 204 and the second temperature sensor 303 are all electrically connected to the DCS control system 5. The valve 102 is an electric regulating valve. The valve 102, the electric heater 2 and the spray gun 4 are all controlled by the DCS control system 5.

[0040] As the intelligent control core of the entire system, the DCS control system 5 acquires real-time temperature data of the hot air in the second air inlet duct 201 through the first temperature sensor 203, flow rate data of the hot air in the second air inlet duct 201 through the flow indicator transmitter 204, and temperature data of the evaporator 3 through the second temperature sensor 303. Based on this real-time data, the DCS control system 5 can automatically and precisely control the valve 102, electric heater 2, and spray gun 4. For example, when the temperature of the hot air in the second air inlet duct 201 is lower than the set value, the DCS control system 5 controls the electric heater 2 to increase the heating power, and at the same time adjusts the opening of the valve 102 appropriately according to the flow rate to ensure that the appropriate hot air temperature and flow rate enter the evaporator 3; when the temperature in the evaporator 3 is too high, the DCS control system 5 controls the electric heater 2 to reduce the heating power, adjusts the valve 102 to reduce the hot air volume, and can also adjust the ammonia injection amount of the spray gun 4 to maintain the temperature stability in the evaporator 3 and the reasonable evaporation state of the ammonia water.

[0041] The evaporator 3 is equipped with a second pressure gauge 301 for monitoring its internal pressure and a third temperature gauge 302 for monitoring its internal temperature. The second pressure gauge 301 displays the pressure value inside the evaporator 3 in real time, allowing operators to determine whether the pressure inside the evaporator 3 is within the normal operating range. If the pressure rises abnormally, it may be due to poor venting of gases such as ammonia, or an abnormal reaction occurring inside the evaporator 3; if the pressure is too low, it may indicate a leak in the evaporator 3. The third temperature gauge 302 monitors the temperature inside the evaporator 3 in real time, corroborating the data from the second temperature sensor 303, providing operators with more intuitive information about the temperature inside the evaporator 3. This allows them to better understand the evaporation of ammonia water inside the evaporator 3 and coordinate with the DCS control system 5 for appropriate adjustments and control.

[0042] The second air inlet duct 201 is made of carbon steel, and its outer wall is covered with a first insulation layer. The carbon steel material provides good strength and corrosion resistance, enabling it to withstand the transport of hot air. The first insulation layer primarily serves to reduce heat loss. Since the hot air exiting the electric heater 2 is at a high temperature, without insulation, a significant amount of heat would be lost to the surrounding environment during its transport through the second air inlet duct 201 to the evaporator 3, causing a decrease in the temperature of the hot air entering the evaporator 3 and affecting the evaporation efficiency of the ammonia water. The first insulation layer effectively prevents heat transfer, maintains the temperature of the hot air, and improves the overall energy efficiency of the system.

[0043] The ammonia outlet duct is made of 304 stainless steel, and its outer wall is wrapped with a second insulation layer. Because 304 stainless steel has excellent corrosion resistance, it can resist the erosion of corrosive gases such as ammonia, ensuring the service life and safety of the pipeline. The second insulation layer is mainly to prevent condensation of the ammonia during transportation due to temperature drop. This second insulation layer maintains the temperature of the ammonia, ensuring that it is stably transported in gaseous form to the subsequent denitrification reaction unit.

[0044] Both the first and second insulation layers are made of ceramic fiber insulation material. It should be noted that the first temperature sensor 203 and the second temperature sensor 303 are WZP-100 type platinum resistance temperature sensors, and the flow indicator transmitter 204 is an LWGB-50 type turbine flow transmitter.

[0045] In operation, the DCS control system 5 first receives data collected from the first temperature sensor 203 and the flow indicator transmitter 204 on the second air inlet duct 201, as well as the temperature signal from the second temperature sensor 303 on the evaporator 3. The system presets the optimal temperature for ammonia evaporation in the evaporator 3 to be 120°C, and the target temperature for hot air in the second air inlet duct 201 to be 150°C.

[0046] If the first temperature sensor 203 detects that the hot air temperature inside the second air inlet duct 201 is 130℃, which is lower than the target temperature, the DCS control system 5 controls the electric heater 2 to increase its power from the initial 50kW to 80kW, and simultaneously sends a command to the valve 102 to increase its opening from 40% to 60% to increase the primary air volume entering the electric heater 2, causing the hot air temperature to rise rapidly. During this process, the flow indicator transmitter 204 monitors the hot air flow rate changes in real time and feeds the data back to the DCS control system 5 to ensure that the flow rate remains stable at the preset value of 200m³ / h.

[0047] When the second temperature sensor 303 detects that the temperature inside the evaporator 3 has reached 115℃, approaching the optimal evaporation temperature, the DCS control system 5 begins to fine-tune the power of the electric heater 2 to 70kW and adjusts the opening of valve 102 back to 55%, maintaining the hot air temperature at 150℃±5℃. Simultaneously, based on the temperature and hot air flow data inside the evaporator 3, the DCS control system 5 controls the spray gun 4 to spray ammonia water into the evaporator 3 at a flow rate of 5L / min, ensuring sufficient contact between the ammonia water and the hot air for efficient evaporation.

[0048] If, during operation, the second temperature sensor 303 detects that the temperature inside the evaporator 3 exceeds 125°C, the DCS control system 5 immediately issues a command to reduce the power of the electric heater 2 to 50kW and simultaneously close the valve 102 to 45% to reduce the hot air volume. If the temperature continues to rise to 130°C, the DCS control system 5 controls the spray gun 4 to stop spraying ammonia until the temperature returns to the normal range, ensuring the safe operation of the system.

[0049] Throughout the entire control process, the DCS control system 5 continuously optimizes the power of the electric heater 2, the opening degree of valve 102, and the amount of ammonia injected by the spray gun 4 by collecting data from various sensors in real time, so that the system is always in a stable and efficient operating state, achieving precise control of the ammonia evaporation temperature and rational utilization of energy.

[0050] The foregoing has shown and described the basic principles of the present invention. The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. The above embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Any modifications, equivalent substitutions, and improvements made within the scope of the present invention without departing from the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. An ammonia water evaporation system for flue gas denitrification, characterized in that, include: The primary air duct (1) of the boiler is formed by heating the high-temperature flue gas generated by the boiler combustion through an air preheater. An electric heater (2) has its air inlet connected to the primary air duct (1) of the boiler via a first air inlet pipe (101). Evaporator (3), the outlet of the electric heater (2) is connected to the inlet of the evaporator (3) through the second air inlet pipe (201), the lower end of the interior of the evaporator (3) is equipped with a spray gun for spraying ammonia water into the interior of the evaporator (3), and the top of the evaporator (3) is connected to an ammonia gas outlet pipe (304).

2. The ammonia water evaporation system for flue gas denitrification according to claim 1, characterized in that: A valve (102) is installed on the first air inlet duct (101).

3. The ammonia water evaporation system for flue gas denitrification according to claim 1, characterized in that: The first air inlet duct (101) is equipped with a first pressure indicator (104) for monitoring the pressure of the first air inlet duct (101) and a first temperature indicator (103) for monitoring the internal air temperature.

4. The ammonia water evaporation system for flue gas denitrification according to claim 1, characterized in that: A second temperature indicator (202) for monitoring the air temperature inside the second air inlet duct (201) is installed on the second air inlet duct (201).

5. The ammonia water evaporation system for flue gas denitrification according to claim 2, characterized in that: It also includes a DCS control system (5), a first temperature sensor (203) and a flow indicator transmitter (204) are installed on the second air inlet duct (201), and a second temperature sensor (303) is installed on the evaporator (3). The first temperature sensor (203), the flow indicator transmitter (204) and the second temperature sensor (303) are all electrically connected to the DCS control system (5). The valve (102) is an electric regulating valve. The valve (102), the electric heater (2) and the spray gun (4) are all controlled by the DCS control system (5).

6. The ammonia water evaporation system for flue gas denitrification according to claim 1, characterized in that: The evaporator (3) is equipped with a second pressure gauge (301) for monitoring its internal pressure and a third temperature gauge (302) for monitoring its internal temperature.

7. The ammonia water evaporation system for flue gas denitrification according to claim 1, characterized in that: The second air inlet duct (201) is a carbon steel duct, and the outer wall of the second air inlet duct (201) is wrapped with a first insulation layer.

8. The ammonia water evaporation system for flue gas denitrification according to any one of claims 1-7, characterized in that: The ammonia gas outlet pipe (304) is a 304 stainless steel pipe, and the outer wall of the ammonia gas outlet pipe (304) is wrapped with a second insulation layer.

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