Automatic ammonia preparation device for adding ammonia water to outlet of deaerator

Abstract

The utility model discloses an automatic ammonia preparation device for adding ammonia water to an outlet of a deaerator, and relates to the technical field of thermal power generation or industrial boiler water treatment, the automatic ammonia preparation device comprises an ammonia water storage tank and a mixing tank, one side of the ammonia water storage tank is communicated with a concentrated ammonia water pump, and the output end of the concentrated ammonia water pump is communicated with an ammonia supply pipeline; one end of the ammonia supply pipeline is communicated with one side of the mixing tank; one end of the dilution water pipeline is communicated with a dilution water pump, the output end of the dilution water pump and one side of the mixing tank are communicated with a chemical feeding pipeline, the chemical feeding pipeline is communicated with one side of the mixing tank, one end of the chemical feeding pipeline is communicated with a deaerator outlet pipe, one end of the deaerator outlet pipe is provided with a chemical feeding point, and the other end of the deaerator outlet pipe is provided with a chemical feeding pipe. An atomizing nozzle is mounted in the dosing point, and a static mixer is mounted in the dosing pipeline; and a signal transmission line is respectively formed between the PLC and the ammonia water storage tank and between the PLC and the mixing tank.

Description

An automatic ammonia mixing device for adding ammonia water to the outlet of a deaerator Technical Field

[0001] This utility model relates to the field of thermal power generation or industrial boiler water treatment technology, specifically an automatic ammonia mixing device for adding ammonia water to the outlet of a deaerator. Background Technology

[0002] In thermal systems, to prevent metal corrosion, ammonia is added to the deaerator outlet feedwater to adjust the pH to 8.5–9.5. Traditional ammonia addition methods have the following problems:

[0003] 1. Manual adjustment lag: Relying on manual pH testing and untimely adjustment of ammonia dosage can easily lead to water quality fluctuations;

[0004] 2. Crude concentration control: Directly adding a fixed concentration of ammonia water without dynamically adjusting the ratio according to the water flow rate and initial pH value may result in local over-concentration or under-concentration;

[0005] 3. Safety hazards: The lack of real-time leakage monitoring during the storage and transportation of ammonia water, and uneven mixing can easily lead to pipeline corrosion.

[0006] Therefore, there is an urgent need for an automated, precise, safe and reliable automatic ammonia mixing device. Summary of the Invention

[0007] The purpose of this invention is to provide an automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator, so as to solve the problems mentioned in the background art.

[0008] By adopting the above technical solution, a device has been developed that can automatically adjust the ammonia concentration and dosage according to the water quality parameters at the deaerator outlet, and also has leakage monitoring and efficient mixing functions, thus solving the shortcomings of traditional ammonia addition methods.

[0009] In view of the above problems, the technical solution proposed by this utility model is as follows:

[0010] An automatic ammonia mixing device for adding ammonia water to the outlet of a deaerator includes an ammonia water storage tank and a mixing tank. A concentrated ammonia water pump is connected to one side of the ammonia water storage tank, and the output end of the concentrated ammonia water pump is connected to an ammonia supply pipeline. One end of the ammonia supply pipeline is connected to one side of the mixing tank. A dilution water pipeline is connected to one end of a dilution water pump, and the output end of the dilution water pump is connected to one side of the mixing tank via a dosing pipeline. The dosing pipeline is connected to one side of the mixing tank, and one end of the dosing pipeline is connected to a deaerator outlet pipe. A dosing point is provided at one end of the deaerator outlet pipe, and an atomizing nozzle is installed inside the dosing point. A static mixer is installed inside the dosing pipeline. A PLC controller forms signal transmission lines with both the ammonia water storage tank and the mixing tank, and a human-machine interface is provided on the outside of the PLC controller.

[0011] As a preferred embodiment of this utility model, a liquid level sensor and a temperature sensor are respectively installed on the inner wall of the ammonia storage tank, and the liquid level sensor and the temperature sensor are arranged longitudinally.

[0012] As a preferred embodiment of this utility model, a breather valve is connected to one side of the outer wall of the ammonia storage tank.

[0013] As a preferred embodiment of this utility model, the ammonia supply pipeline is internally equipped with a first electric regulating valve and a first flow meter.

[0014] As a preferred embodiment of this utility model, a second electric regulating valve and a second flow meter are installed inside the dilution water pipeline.

[0015] As a preferred embodiment of this invention, a pH sensor is installed inside the deaerator outlet pipe.

[0016] As a preferred embodiment of this utility model, a leakage sensor is installed at the bottom of the ammonia storage tank and at the connection between the ammonia storage tank and the concentrated ammonia pump, and the leakage sensor has a built-in audible and visual alarm.

[0017] As a preferred embodiment of this utility model, an emergency shut-off valve is connected at the connection between the ammonia storage tank and the concentrated ammonia pump.

[0018] As a preferred embodiment of this invention, a stirrer is installed inside the mixing tank.

[0019] On the other hand, this utility model provides a method for an automatic ammonia mixing device to add ammonia water to the outlet of a deaerator, comprising the following steps:

[0020] Step 1: Automatic Proportioning

[0021] The PLC controller calculates the required diluted ammonia concentration (C1) based on the deviation between the real-time pH value detected by the pH sensor and the target value, combined with the water supply flow rate (Fw) and the initial ammonia concentration (C0), using the formula C1 = (pH target - pH measured) × K × Fw / F1. It then controls the frequency conversion of the concentrated ammonia pump and the dilution water pump to adjust the ratio of concentrated ammonia to dilution water.

[0022] Step 2, Precise Dosing:

[0023] The diluted ammonia water is atomized through atomizing nozzles and enters the deaerator outlet pipe, where it is further mixed by a static mixer to ensure that the pH value is stable within the target range.

[0024] Step 3: Security Monitoring

[0025] The leakage sensor monitors leakage in real time. In case of an abnormality, the emergency shut-off valve cuts off the gas supply, the audible and visual alarm sounds, and the human-machine interface displays the location of the fault.

[0026] Compared with the prior art, the beneficial effects of this utility model are:

[0027] 1. Dynamic ratio: The ammonia concentration is adjusted in real time according to the water quality, avoiding the drawbacks of adding a fixed concentration;

[0028] 2. Precise control: The PLC algorithm combines flow rate and pH value for dual parameter adjustment, with a response time of less than 30 seconds and a pH fluctuation range of ≤ ±0.2.

[0029] 3. Safe and reliable: Leakage monitoring and emergency shut-off are linked to reduce the risk of ammonia leakage;

[0030] 4. High-efficiency mixing: The combination of atomizing nozzles and static mixers improves the uniformity of ammonia water and feed water mixing by more than 90%. Attached Figure Description

[0031] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof.

[0032] Figure 1 is a schematic diagram of an automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator provided by this utility model.

[0033] In the diagram: 100, ammonia storage tank; 101, level sensor; 102, temperature sensor; 103, breather valve; 200, mixing tank; 300, PLC controller; 400, ammonia supply pipeline; 401, concentrated ammonia pump; 402, first electric regulating valve; 403, first flow meter; 500, dilution water pipeline; 501, second electric regulating valve; 502, second flow meter; 503, dilution water pump; 600, chemical dosing pipeline; 700, deaerator outlet pipe. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this application, unless otherwise stated, "multiple" means two or more.

[0036] Please refer to Figure 1. This utility model provides a technical solution: an automatic ammonia mixing device for adding ammonia water to the outlet of a deaerator, including an ammonia water storage tank 100 and a mixing tank 200. A concentrated ammonia water pump 401 is connected to one side of the ammonia water storage tank 100, and the output end of the concentrated ammonia water pump 401 is connected to an ammonia supply pipeline 400. One end of the ammonia supply pipeline 400 is connected to one side of the mixing tank 200. A dilution water pipeline 500 is also included, with one end connected to a dilution water pump 503. The output end of the dilution water pump 503 is connected to the mixing tank 200. A dosing pipe 600 is connected to one side of the mixing tank 200. One end of the dosing pipe 600 is connected to the deaerator outlet pipe 700. A dosing point is provided at one end of the deaerator outlet pipe 700. An atomizing nozzle is installed inside the dosing point. A static mixer is installed inside the dosing pipe 600. A PLC controller 300 forms a signal transmission line with the ammonia storage tank 100 and the mixing tank 200 respectively. A human-machine interface is provided on the outside of the PLC controller 300.

[0037] Example 1

[0038] Ammonia Mixing Unit: Construction of Dynamic Proportioning System

[0039] 1. Design and installation of ammonia storage tank 100

[0040] Structural parameters: The tank is made of 304 stainless steel, and its volume is designed according to the daily ammonia consumption of the power plant (e.g., a 300MW unit consumes approximately 200L per day, so the tank volume is set at 1000L) to meet 3-5 days of storage needs. Tank configuration:

[0041] Liquid level sensor 101: Magnetic float level gauge (accuracy ±1mm) is selected to monitor the ammonia water level in real time and link with PLC controller 300 to realize low liquid level alarm (threshold set to 200L) and automatic ammonia replenishment prompt;

[0042] Temperature sensor 102: Pt100 resistance temperature detector (accuracy ±0.5℃), monitors the temperature inside the tank to prevent ammonia from evaporating due to high temperature, and starts the tank cooling water circulation when the temperature exceeds 35℃;

[0043] Breathing valve 103: Sets a pressure release threshold (positive pressure 10kPa, negative pressure -5kPa) to balance the air pressure inside the tank and prevent the tank from deforming.

[0044] Installation requirements: The tank body should be fixed on a corrosion-resistant foundation with a distance of ≥300mm from the ground to facilitate the placement of leak sensors; the inlet should be connected to the 401 inlet pipe of the concentrated ammonia pump using a corrosion-resistant flexible hose to reduce the impact of vibration.

[0045] 2. Dilution water system configuration

[0046] Water source selection: Prioritize connection to demineralized water pipeline (water conductivity <10μS / cm), or condensate recovery pipeline (a filter needs to be added to remove impurities such as iron ions) to ensure the purity of the dilution water.

[0047] Piping components:

[0048] First electric regulating valve 402: A pneumatic diaphragm regulating valve (accuracy ±1%) is selected, which is linked with PLC controller 300 to regulate the dilution water flow rate;

[0049] First flow meter 403: Electromagnetic flow meter (range 0~500L / h, accuracy ±0.5%), which monitors the instantaneous flow rate of dilution water in real time and provides data for proportion calculation.

[0050] 3. Selection and Control of Metering Pump Sets

[0051] Pump parameters: Both the concentrated ammonia water pump 401 and the dilution water pump 503 are plunger-type variable frequency metering pumps.

[0052] Flow range: Concentrated ammonia water pump 401 is 0~100L / h (suitable for concentrated ammonia water dosing requirements), and dilution water pump 503 is 0~500L / h (matching dilution water flow rate);

[0053] Control accuracy: Variable frequency drive resolution 0.1Hz, corresponding to flow rate regulation accuracy ±0.5%;

[0054] Sealing method: Double mechanical seal + nitrogen purging to prevent ammonia leakage and adapt to corrosive media.

[0055] Linkage logic: The PLC controller 300 calculates the frequency ratio of concentrated ammonia pump 401 / dilution pump 503 according to the target concentration. For example, when 3% ammonia water is needed, the frequency of concentrated ammonia pump 401 is controlled at 20Hz (flow rate 40L / h) and the frequency of dilution pump 503 is controlled at 50Hz (flow rate 400L / h) to ensure a volume ratio of 1:10.

[0056] 4. Optimized design of mixing tank

[0057] Structural parameters: 20L volume (to meet the maximum dosing capacity reserve for 5 minutes), with the inner wall treated with polytetrafluoroethylene for corrosion protection;

[0058] Mixing system: Employs a paddle mixer with an adjustable speed of 0-300 rpm, linked to a metering pump unit.

[0059] When the dosage is less than 50L / h, the rotation speed is set to 100rpm;

[0060] When the dosage is ≥50L / h, the rotation speed is automatically increased to 200rpm to ensure that the mixing uniformity error is ≤2% (verified by sampling test);

[0061] Inlet and outlet design: The inlet is divided into two lines, which are connected to the outlets of concentrated ammonia water pump 401 and dilution water pump 503 respectively. The pipes are connected to the tank at a 45° angle to enhance the turbulent mixing effect; the outlet pipe has a diameter of DN25 and the flow velocity is controlled at 1~2m / s to avoid pressure loss.

[0062] Example 2

[0063] Control Unit: Intelligent Algorithms and System Integration

[0064] 1. Sensor placement and signal acquisition

[0065] pH sensor: Installed on the straight section of the deaerator outlet pipe (≥5 times the pipe diameter from the bend), using a flow-through mounting bracket to ensure a stable water sample flow rate (0.5~1m / s);

[0066] Sensor selection: Glass electrode pH meter (range 0~14, accuracy ±0.01pH), with temperature compensation function (built-in Pt100 sensor), data updated every 10 seconds;

[0067] Pretreatment measures: Use a 10μm precision filter to remove suspended solids from the water sample to avoid contaminating the electrode. Calibrate regularly (weekly) with standard buffer solutions (pH=4.01, pH=9.18).

[0068] Data transmission: All sensor signals are connected to the PLC controller 300 via 4-20mA analog input or Modbus RTU digital input. Shielded twisted-pair cables are used for transmission, and the system is kept away from sources of strong electromagnetic interference (such as motors and frequency converters).

[0069] 2. PLC control algorithm implementation

[0070] Mathematical model establishment: Based on acid-base neutralization reactions and the law of conservation of mass, the formula for the concentration of ammonia after dilution is derived:

[0071] C1 = C0 × Q1 / (Q1 + Q2)

[0072] in:

[0073] C0 represents the initial concentration of concentrated ammonia solution (20%–25%, manually entered into HMI);

[0074] Q1 is the flow rate of concentrated ammonia solution (L / h, P1 is the real-time flow rate);

[0075] Q2 is the dilution water flow rate (L / h, P2 is the real-time flow rate).

[0076] Target dosage calculation:

[0077] When there is a deviation between the measured pH value (measured pH) and the target pH value (target pH), the required C1 is calculated according to the water supply flow rate (Fw, unit t / h) and the ammonia ionization equilibrium constant (K = 1.8 × 10^-5) through the following steps:

[0078] 1) Calculate the target hydroxide ion concentration:

[0079] [OH-] target = 10^pH target - 14;

[0080] 2) Calculate the measured hydroxide ion concentration:

[0081] [OH-] measured = 10^pH measured - 14;

[0082] 3) Required molar concentration of ammonia:

[0083] ΔC = [OH-]target - [OH-]measured (ignoring the effect of ammonia's own dissociation equilibrium);

[0084] 4) Target dilution ammonia flow rate:

[0085] Qtotal = ΔC × Fw × 1000 / C1 × ρ (ρ is the density of ammonia, taken as 0.96 g / cm2) 3 );

[0086] 5) Combining C1=C0×Q1 / (Q1+Q2) and Qtotal=Q1+Q2, calculate Q1 and Q2, and output them to frequency converters P1 and P2.

[0087] Control strategy: The PID algorithm is used for dynamic adjustment, with a proportional coefficient Kp = 0.8, integral time Ti = 60s, and derivative time Td = 10s, ensuring a response time of <30 seconds and an overshoot of <5%.

[0088] 3. Human-computer interface function design

[0089] User interface:

[0090] Real-time data displays include: pH value, water flow rate, ammonia concentration, pump frequency, and tank level / temperature.

[0091] Parameter settings: target pH value (default 9.2, adjustable within the range of 8.5 to 9.5), alarm thresholds (low / high liquid level, excessively high temperature, pH exceeding limit);

[0092] Mode switching: Automatic mode (PLC control), manual mode (for on-site debugging, GV1, P1, and P2 can be adjusted individually);

[0093] Fault diagnosis: Real-time display of sensor faults, pump overload, valve jamming, etc., and supports historical data query.

[0094] Example 3

[0095] 1. Selection and installation of atomizing nozzles

[0096] Structural design: An air-assisted atomizing nozzle is selected, with an atomization particle size ≤50μm, to ensure that ammonia water is sprayed into the center of the water flow in a fine mist;

[0097] Installation location: Make a hole at the axial center of the deaerator outlet pipe, with the nozzle axis at a 45° angle to the water flow direction, and keep it at a distance of ≥3 times the pipe diameter from the upstream bend to avoid water flow deviation affecting the atomization effect;

[0098] Pressure control: The pressure of the atomizing gas source (compressed air) is stabilized at 0.4-0.6MPa. It is linked with the metering pump and automatically increases the air pressure when the dosage is >80L / h to improve the uniformity of atomization.

[0099] 2. Static Mixer Configuration

[0100] Model selection: SV type spiral blade mixer, pipe diameter DN50, length 300mm (5 times the pipe diameter), number of blades 12, each blade twist angle 180°, to ensure that the concentration deviation after mixing is ≤1%;

[0101] Installation requirements: Connect pressure gauges (accuracy ±1%) in series 500mm downstream of the atomizing nozzle, and monitor the pressure drop in real time. When the pressure drop is >0.1MPa, prompt for cleaning.

[0102] Example 4

[0103] 1. Leakage sensor (S2) arrangement

[0104] Monitoring points: At the bottom of the ammonia storage tank, one combustible gas sensor (detecting ammonia concentration, range 0-1000ppm, accuracy ±5%) is installed every 1m along the perimeter of the tank bottom; at the pipeline interface, contact leak detection strips are installed at easy-to-leak points such as the inlet of concentrated ammonia pump 401 and the flanges before and after the first electric regulating valve 402 to monitor liquid leakage in real time.

[0105] Linkage logic: When any sensor detects an ammonia concentration >200ppm or a liquid leak signal, the following actions are triggered:

[0106] 1) When the audible and visual alarm is activated, both the on-site and control room alarms are triggered simultaneously;

[0107] 2) The PLC controller 300 sends a command to the emergency shut-off valve to close the outlet valve of the ammonia storage tank 100 within 5 seconds;

[0108] 3) Automatically stop the operation of concentrated ammonia water pump 401 and dilution water pump 503 to cut off the dosing process;

[0109] 4) The human-machine interface displays the location of the leak and generates a fault log.

[0110] 2. Safety Redundancy Design

[0111] The tank area is equipped with a dike (500mm high, volume ≥ 110% of tank capacity), and the bottom is covered with an anti-corrosion epoxy resin coating.

[0112] Configure an ammonia absorption device (spray system) that is linked to a leak sensor. When a leak is detected, it will automatically spray a dilute sulfuric acid solution to neutralize the ammonia.

[0113] Secondly, the system performance optimization strategies are as follows:

[0114] 1. Algorithm iteration: Based on data accumulated under different operating conditions (such as unit start-up and shutdown, load fluctuations), optimize PID parameters, for example, increase integral time and reduce adjustment frequency under low load;

[0115] 2. Energy Management: While ensuring mixing effect, dynamically adjust the stirrer speed according to the dosage (e.g., reduce to 80 rpm when the dosage is <30L / h) to reduce power consumption;

[0116] 3. Data traceability: By recording historical data from the PLC, the correlation between pH value and unit load and feedwater temperature is analyzed, a multivariate prediction model is established, and the dosing strategy is adjusted in advance.

[0117] The following is an example:

[0118] (I) Scope of Implementation

[0119] 1. Target of renovation: 2 units of 300MW each, each equipped with 1 set of automatic ammonia distribution device, connected to the deaerator outlet DN300 pipeline (design flow rate 1200t / h);

[0120] 2. System Integration: Communicates with the power plant's DCS system, uploads data such as pH value and dosage in real time, and receives remote start / stop commands.

[0121] (II) Comparison of Implementation Results

[0122]

[0123] (III) Benefit Analysis

[0124] Corrosion reduction: After pH stabilizes, the corrosion rate of water supply pipes and boiler tube bundles decreases from 0.15 mm / year to 0.05 mm / year, saving 14,600 liters of ammonia water annually.

[0125] In the embodiments provided in this application, it should be understood that the disclosed systems, modules, and methods can be implemented in other ways. For example, the module embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between modules or units, and may be electrical, mechanical, or other forms.

[0126] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. This application is not limited to the exact structures described above and illustrated in the accompanying drawings, and it should not be considered that the specific implementation of this application is limited to these descriptions. For those skilled in the art, various changes and modifications made without departing from the concept of this application should be considered to fall within the protection scope of this application.

Claims

1. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator, characterized in that, include: An ammonia storage tank (100) and a mixing tank (200) are provided. A concentrated ammonia pump (401) is connected to one side of the ammonia storage tank (100). The output end of the concentrated ammonia pump (401) is connected to an ammonia supply pipeline (400), one end of which is connected to one side of the mixing tank (200). A dilution water pipeline (500) is provided. One end of the dilution water pipeline (500) is connected to a dilution water pump (503). The output end of the dilution water pump (503) is connected to one side of the mixing tank (200) via a dosing pipeline (600). 600) is connected to one side of the mixing tank (200), one end of the dosing pipe (600) is connected to the deaerator outlet pipe (700), one end of the deaerator outlet pipe (700) is provided with a dosing point, the dosing point is equipped with an atomizing nozzle, and the dosing pipe (600) is equipped with a static mixer; PLC controller (300) is configured to form a signal transmission line with the ammonia storage tank (100) and the mixing tank (200) respectively, and the PLC controller (300) is provided with a human-machine interface on the outside.

2. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator according to claim 1, characterized in that, The inner wall of the ammonia storage tank (100) is equipped with a liquid level sensor (101) and a temperature sensor (102), which are arranged longitudinally.

3. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator according to claim 1, characterized in that, A breather valve (103) is connected to one side of the outer wall of the ammonia storage tank (100).

4. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator according to claim 1, characterized in that, The ammonia supply pipeline (400) is equipped with a first electric regulating valve (402) and a first flow meter (403).

5. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator according to claim 1, characterized in that, The dilution water pipe (500) is equipped with a second electric regulating valve (501) and a second flow meter (502).

6. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator according to claim 1, characterized in that, A pH sensor is installed inside the deaerator outlet pipe (700).

7. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator according to claim 1, characterized in that, A leak sensor is installed at the bottom of the ammonia storage tank (100) and at the connection between the ammonia storage tank (100) and the concentrated ammonia pump (401). The leak sensor has a built-in audible and visual alarm.

8. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator according to claim 7, characterized in that, An emergency shut-off valve is connected at the connection between the ammonia storage tank (100) and the concentrated ammonia pump (401).

9. An automatic ammonia dispensing device for adding ammonia water to the outlet of a deaerator according to claim 1, characterized in that, The mixing tank (200) is equipped with a paddle agitator inside.

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