Distributed ammonia gas leakage monitoring system
By combining laser absorption spectroscopy and a distributed optical fiber absorption cell, the accuracy and reliability issues of existing ammonia leak monitoring on ammonia-fueled ships have been resolved, achieving efficient and low-cost ammonia leak detection, suitable for multi-point online monitoring on ammonia-fueled ships.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2026-03-31
AI Technical Summary
Current methods for monitoring ammonia leaks on ammonia-fueled ships mainly rely on electrochemical sensors, which suffer from low detection accuracy, susceptibility to interference, high false alarm rates, and high maintenance costs, making it difficult to meet the safety requirements of ammonia-fueled ships.
Using laser absorption spectroscopy and a distributed fiber optic absorption cell, and through a laser driver module, fiber optic splitter, fiber optic absorption cell, optical switch, photodetector, and photoelectric signal processing module, multi-point online ammonia concentration monitoring is achieved. Quantitative analysis is performed using the selective absorption of the 1512nm laser wavelength and the Lambert-Beer law.
It achieves high-precision, low-false-alarm-rate ammonia leak monitoring, is suitable for multi-point online monitoring of ammonia-fueled ships, reduces maintenance costs, and improves safety.
Smart Images
Figure CN224066621U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of environmental monitoring technology, specifically relating to a distributed ammonia leak monitoring system. Background Technology
[0002] Ammonia-fueled ships are vessels that use ammonia (NH3) as their power source instead of traditional fossil fuels. When burned, they produce only nitrogen and water vapor, without releasing carbon dioxide, thus achieving low-carbon or zero-carbon emissions for the shipping industry. Furthermore, ammonia fuel is stable in price, resulting in lower long-term operating costs compared to traditional fuels. However, ammonia-fueled ships have not yet been commercialized on a large scale, and a major challenge they face is the toxicity and corrosiveness of ammonia, requiring strict control of leakage risks.
[0003] Existing ammonia leak monitoring mainly uses electrochemical sensors, which are low in cost and easy to deploy. However, they are susceptible to interference from other gases, have low detection accuracy, high false alarm rate, and high concentrations of ammonia can easily cause sensor poisoning and failure, resulting in high maintenance costs. Therefore, they are not suitable for monitoring ammonia leaks on ammonia-fueled ships. Utility Model Content
[0004] The purpose of this invention is to provide a distributed ammonia leak monitoring system that overcomes the shortcomings of existing electrochemical sensors. By utilizing laser absorption spectroscopy and a distributed optical fiber absorption cell, it enables multi-point online monitoring of ammonia leaks. This system can monitor the ammonia leak concentration in the fuel supply system area of ammonia-fueled ships in real time, provide leak alarm information, improve the environmental safety of ammonia-fueled ships, and avoid personnel and property losses caused by leaks.
[0005] Specifically, this utility model provides the following technical solution:
[0006] A distributed ammonia leak monitoring system includes a laser driver module, a laser, an optical fiber splitter, an optical fiber absorber, an optical switch, a photodetector, a photoelectric signal processing module, and a display and alarm module.
[0007] The laser driver module is connected to the laser, and the output port of the laser is connected to the input port of the fiber optic splitter.
[0008] The fiber optic splitter is equipped with multiple output ports, each of which is connected to the input port of an independent fiber optic absorption cell.
[0009] The input port of the optical switch can be selectively connected to the output port of any optical fiber absorption cell; the output port of the optical switch is connected to the input port of the photodetector; the output port of the photodetector is connected to the input port of the photoelectric signal processing module; and the output port of the photoelectric signal processing module is connected to the input port of the display alarm module.
[0010] In the distributed ammonia leak monitoring system provided by this utility model, the laser drive module drives and modulates the output light of the laser, and the fiber optic splitter divides the laser beam into multiple paths, with each path having an intensity that is at least at the minimum intensity required for detection. The split laser beam is transmitted through an optical fiber to a fiber optic absorption cell, which contains the gas to be tested. When light of a specific wavelength passes through the fiber optic absorption cell, if the gas to be tested contains ammonia molecules, it will selectively absorb photons, resulting in attenuation of the light intensity. The laser beam transmitted through the fiber optic absorption cell is transmitted to an optical switch module. The optical switch module selects one light output at a time and cycles through the output of each detection light to a photodetector. The light intensity signal after absorption by the gas is converted into an electrical signal and sent to the photoelectric signal processing module for processing. By analyzing the change in absorbance (following the Lambert-Beer law), the ammonia concentration in each fiber optic absorption cell can be quantitatively analyzed and displayed on the display of the alarm module. According to the set program judgment conditions, an alarm message is output when the ammonia concentration is too high.
[0011] Preferably, the laser wavelength is 1512 nm. The choice of laser wavelength is related to the position of the gas absorption peak. Ammonia has multiple absorption peaks, but the intensity of different absorption peaks and their overlap with other gases are different. Studies have found that when the laser wavelength is selected at 1512 nm, the absorption peak of ammonia is strong and does not overlap with the absorption peaks of other gases, thus avoiding cross-interference.
[0012] Preferably, the optical fiber absorption cell has an absorption path length of 2.8–3.2 m. Studies have found that using an absorption path length within this range can meet the requirements for ppm-level ammonia detection, while also maintaining a small size.
[0013] Preferably, the input port of the optical switch switches the connected optical fiber absorption cells at preset intervals, so that the optical fiber absorption cells are alternately connected to the optical switch to detect different optical fiber absorption cells.
[0014] Preferably, the photodetector operates in the 800-1700nm band. This band exhibits strong responsivity near the target band of 1512nm, which meets the detection requirements.
[0015] Preferably, the system also includes a power supply module, which is connected to the laser driver module, the photoelectric signal processing module, and the display and alarm module, respectively, and is used to supply power to the entire system.
[0016] The beneficial effects achieved by this utility model are as follows:
[0017] (1) The distributed ammonia leak monitoring system provided by this utility model can quickly and effectively monitor the ammonia concentration at multiple locations. It has high detection accuracy, short response time, is not affected by other gases, has an extremely low false alarm rate, and a long service life. It is very suitable for monitoring ammonia leaks on ammonia-fueled ships.
[0018] (2) The distributed ammonia leak monitoring system provided by this utility model only requires a single set of laser, photoelectric detector and signal processing circuit to realize real-time online monitoring of ammonia leaks at multiple points. It is a cost-effective ammonia leak monitoring system solution.
[0019] (3) The distributed ammonia leakage monitoring system provided by this utility model preferably has a laser wavelength of 1512nm. At this wavelength, the absorption peak of ammonia is strong and does not overlap with the absorption peaks of other gases, thus avoiding cross-interference. Attached Figure Description
[0020] Figure 1 This is a simplified structural diagram of a distributed ammonia leak monitoring system in Example 1. Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model. Where specific technologies or conditions are not specified in the embodiments, they shall be performed in accordance with the technologies or conditions described in the literature in the field, or in accordance with the product manual.
[0022] Example 1
[0023] A distributed ammonia leak monitoring system, see [link / reference] Figure 1 It includes a power supply module, a laser driver module, a laser, an optical fiber splitter, eight optical fiber absorption cells, an optical switch, a photodetector, an optical signal processing module, and a display and alarm module.
[0024] The power module converts 24V voltage to 5V and 3.3V voltages to power the laser driver module and the optoelectronic signal processing module.
[0025] A 1512nm DFB laser is selected as the laser. The laser drive module applies the drive current of the superimposed modulation signal to the laser drive terminal, so that the laser emits 1512nm laser light. In addition, the laser drive module also drives the laser's TEC controller to stabilize the laser temperature at 25℃.
[0026] The laser output light is connected to an optical fiber splitter via optical fiber. The optical fiber splitter has 8 output ports, which divide the laser into 8 equal paths. Each laser path is then connected to 8 optical fiber absorption cells located at different monitoring points via optical fiber.
[0027] The fiber optic absorption cell adopts a diffusion-inlet method, with dimensions of 68mm*51mm*25mm and an absorption optical path of 3m. After the laser in the fiber optic absorption cell is absorbed by the gas, each laser path is connected to an 8-input, 1-output optical switch module through the fiber optic output port of the fiber optic absorption cell. The optical switch is controlled by a program to switch one optical output path every 2 seconds. After detection by a photodetector, a photocurrent signal is output. The photoelectric signal processing module then inverts the gas concentration information in the light intensity absorption signal and sends it to the display screen of the display and alarm module. Based on the program judgment conditions, an alarm message is output, which can be uploaded to the ship's main control room through the communication interface.
[0028] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.
Claims
1. A distributed ammonia leak monitoring system, characterized in that, The application relates to a laser absorption gas detection system, which comprises a laser driving module, a laser, a fiber splitter, a fiber absorption cell, an optical switch, a photoelectric detector, a photoelectric signal processing module and a display alarm module. The laser driving module is connected with the laser, and the output port of the laser is connected with the input port of the fiber splitter. The fiber splitter is provided with a plurality of output ports, and each output port is connected with the input port of an independent fiber absorption cell. The input port of the optical switch is selectively connected with the output port of any fiber absorption cell, the output port of the optical switch is connected with the input port of the photoelectric detector, the output port of the photoelectric detector is connected with the input port of the photoelectric signal processing module, and the output port of the photoelectric signal processing module is connected with the input port of the display alarm module.
2. The distributed ammonia leak monitoring system of claim 1, wherein, The laser wavelength of the laser is 1512 nm.
3. The distributed ammonia leak monitoring system of claim 1 or 2, wherein, The absorption light path of the fiber absorption cell is 2.8-3.2 m.
4. The distributed ammonia leak monitoring system of claim 1 or 2, wherein, The input port of the optical switch switches the connected fiber absorption cell every preset time length, so that the fiber absorption cells are alternately connected into the optical switch and different fiber absorption cells are detected.
5. The distributed ammonia leak monitoring system of claim 1 or 2, wherein, The wave band of the photoelectric detector is 800-1700 nm.
6. The distributed ammonia leak monitoring system of claim 1 or 2, wherein, The application further comprises a power module, which is connected with the laser driving module, the photoelectric signal processing module and the display alarm module respectively and is used for supplying power to the whole system.