Low-temperature water removal trap device for direct-method non-methane total hydrocarbon analyzer

Abstract

The low-temperature water removal trap device comprises an outer frame, the outer frame is a heat preservation frame, a refrigeration heat conduction block is arranged in the outer frame, a water removal pipe is arranged in the refrigeration heat conduction block, Peltiers are installed on the two sides of the refrigeration heat conduction block respectively, openings are formed in the two sides in the outer frame, and the water removal pipe is arranged in the outer frame. The pure copper heat dissipation assemblies are tightly attached to the openings in the two sides in the outer frame, are tightly attached to the Peltier patch, and are exposed and fixedly installed on the outer side of the outer frame. By adopting the double-Peltier design, the refrigerating efficiency is improved, and the working temperature is controlled to be about 0-20 DEG C for long-time stable operation; the material and the processing technology of the water removal pipe are optimized, and the operation method is improved; the water removal trap structure is redesigned, and the waterproof sealing and heat preservation performance of the water removal trap is improved; due to the miniaturized modular design, the original design thought of the water removal trap module is abandoned, the independent operation of the water removal trap module is realized, and the disassembly and assembly are convenient.

Description

Technical Field

[0001] The utility model relates to the technical field of low-temperature water removal trap devices, in particular to a low-temperature water removal trap device for a direct method non-methane total hydrocarbon analyzer. Background Art

[0002] The new standard places higher demands on the performance of ambient air non-methane total hydrocarbon monitoring instruments. The small-volume direct injection of quantitative loops widely used for high-concentration non-methane total hydrocarbon samples in fixed pollution source monitoring is no longer applicable. Low-concentration ambient air samples require large-volume, low-temperature concentrated injection using a capture trap.

[0003] For ambient air samples, large volumes of cryogenically concentrated samples need to be injected. If the water in the sample is not removed in advance, it will affect both the qualitative and quantitative analysis of the instrument. If the water vapor content in the sample is high, the following problems will occur:

[0004] 1. After the sample enters the trap, it is easy to freeze under low temperature conditions, causing the trap to be blocked;

[0005] 2. After the sample enters the trap, the filler in the trap will come into contact with water, which will reduce the adsorption efficiency and easily cause adsorption penetration;

[0006] 3. The high water vapor content in the trap and the large specific heat capacity of water can easily lead to a decrease in the heating rate of the trap tube or even failure to reach the desorption temperature;

[0007] 4. Water vapor in the trap enters the FID or mass spectrometer detector, affecting the performance or service life of the detector.

[0008] Therefore, a water removal device needs to be added at the front end of the trap. The current water removal technologies mainly include the following:

[0009] 1) Low-temperature condensation and water removal. Depending on the cooling method, there are various types, including water cooling (which can reach temperatures down to 30°C or ambient temperature), air cooling, refrigerant compression refrigeration, and semiconductor electronic refrigeration. Water and air cooling methods offer poor cooling performance and low water removal efficiency. Compression refrigeration consumes a lot of energy, is difficult to disassemble and replace, and is bulky and heavy. Semiconductor refrigeration is also ineffective, typically only controlling temperatures between 0°C and 10°C. Continuous operation of online instruments leads to rapid aging of refrigeration components, prolonged cooling times, and shortened component lifespan.

[0010] 2) Desiccant absorption and adsorption. Absorption refers to a chemical reaction between water molecules and the desiccant, transforming them into another substance. This type of desiccant is called a chemical desiccant. Adsorption refers to the attachment of water molecules to the desiccant without changing the water itself. This type of desiccant is called a physical desiccant. Desiccant can easily interfere with the sample background and adsorb heavy components in the sample. Furthermore, desiccant replacement is required, making maintenance complex.

[0011] 3) Nafion tubing for water removal. Nafion is a hydrophilic polymer material primarily composed of sulfonic acid groups. When gas passes through Nafion tubing, the hydroxyl groups in the water combine with the sulfonic acid groups on the inner wall of the tubing to form hydrogen bonds, which then transfer to the outside of the tubing and seep out. By precisely controlling the sample flow rate through the Nafion tubing and the humidity difference inside and outside the tubing, effective water removal can be achieved. However, Nafion tubing not only removes water but also other hydroxyl-containing VOCs (such as alcohols, aldehydes, and ketones) in the sample, which can distort the sample.

[0012] 4) Inertial separation. These include cyclone separators and gas-liquid separators. These separators generally utilize special structural designs to separate gas and liquid using centrifugal or gravity forces. However, the disadvantage is that liquid water forms within the device, which requires regular removal.

[0013] Therefore, it is urgent to design a low-temperature water removal trap device for direct non-methane total hydrocarbon analyzer with simple structure, easy disassembly and replacement, little impact on sample components, good water removal effect, stable and durable performance. Utility Model Content

[0014] In order to solve the above technical problems, the utility model designs a low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer.

[0015] The utility model adopts the following technical solutions:

[0016] A low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer includes an outer frame, which is a heat-insulating frame. A refrigeration heat-conducting block is arranged inside the outer frame, a water removal pipe is arranged inside the refrigeration heat-conducting block, Peltiers are respectively installed on both sides of the refrigeration heat-conducting block, and the outer frame has openings on both sides. Pure copper heat dissipation components are tightly installed at the openings on both sides of the outer frame. The pure copper heat dissipation components are installed tightly against the Peltiers and are exposed and fixed on the outside of the outer frame.

[0017] Preferably, both ends of the dewatering pipe and the inner surface of the dewatering pipe are coated with an anti-oxidation layer respectively to prevent the both ends of the dewatering pipe and the inner surface from oxidizing and adsorbing heavy components in the sample.

[0018] Preferably, the outer side of the cooling heat conducting block is coated with a layer of high temperature resistant and waterproof glue to prevent the surrounding condensed water from seeping into the cavity and causing the risk of short circuit in the water pipe heating component.

[0019] Preferably, the gap between the cooling and heat-conducting block and the outer frame is filled with foam glue. Filling the gap in the outer frame with foam glue improves the overall thermal insulation effect of the module.

[0020] Preferably, a heating wire is wound around the water pipe.

[0021] Preferably, the pure copper heat dissipation component includes a pure copper heat sink and a heat dissipation fan, and the pure copper heat sink is installed closely to the Peltier.

[0022] Preferably, the cooling heat conducting block and the Peltier are adhered to each other via thermally conductive silicone grease.

[0023] Preferably, the cooling heat conducting block and the outer frame are respectively formed by two symmetrically distributed half modules assembled by bolts. The miniaturized modular design is convenient for disassembly, assembly and replacement.

[0024] Preferably, the pure copper heat sink is mounted on the outside of the outer frame by means of bolts, and the cooling fan is mounted on the pure copper heat sink by means of bolts.

[0025] Preferably, the water removal pipe is installed in the refrigeration heat conduction block through connecting plates and bolts.

[0026] The beneficial effects of the utility model are as follows: the direct method non-methane total hydrocarbon low-temperature dewatering trap provided by the utility model adopts a double Peltier design to improve the refrigeration efficiency, and the working temperature is controlled at about 0 to -20°C for long-term stable operation; the dewatering pipe material and processing technology are optimized, the operation method is improved, and the adsorption effect on heavy components is greatly reduced so that the recovery rate of non-methane total hydrocarbons of substances such as propane, trichloroethylene, toluene, and ethyl acetate meets the requirements of the main station documents; the dewatering trap structure is redesigned to improve the waterproof sealing and thermal insulation performance of the dewatering trap; the miniaturized modular design abandons the original dewatering trap module design concept, realizes the independent operation of the dewatering trap module, and is easy to disassemble and assemble. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the utility model;

[0028] Figure 2 It is a schematic diagram of the internal structure within the external frame of the utility model;

[0029] In the picture: 1. Outer frame, 2. Refrigeration heat conduction block, 3. Water removal pipe, 4. Peltier, 5. Pure copper heat sink, 6. Cooling fan, 7. Foam. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0031] Example: Figure 1 and Figure 2 As shown, a low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer includes an outer frame 1, a refrigeration heat conduction block 2, a water removal pipe 3, a Peltier 4, a pure copper heat sink 5, a cooling fan 6, and a foam glue 7.

[0032] The ends and inner surfaces of the dewatering pipes are coated with an antioxidant layer. Due to the long-term high humidity and oxygen content within the pipes, the inner walls are susceptible to oxidation and rust. This rust damages the coating on the pipe surface, leaving the active sites on the surface susceptible to adsorption of heavy components in the sample. To address this issue, the pipe material has been optimized, and the cutouts at both ends have been specially processed to ensure that the coating on the inner wall of the pipes is not damaged during the manufacturing process.

[0033] The dewatering tube is wrapped with a heating wire. While common direct heating technology can greatly increase the heating rate, the outer electrons of the iron atoms on the surface of the dewatering tube become very active under the condition of electricity, making them easily oxidized. In addition, the heating rate of the dewatering tube has no significant effect on the sample peak shape, so the traditional heating wire heating process is used.

[0034] In the method, a sample transfer sequence is added between the sampling and analysis sequences. By heating the dewatering tube to 20°C to 50°C, the sample adsorbed by the tube wall in the dewatering tube is first analyzed out. At the same time, due to the low temperature, the water cannot be heated to a gaseous state, thereby reducing the influence of the dewatering trap on sample adsorption and improving the sample recovery rate.

[0035] The dewatering pipe material is selected to reduce the impact of the dewatering trap module background on the system blank test. At the same time, in order to avoid ice blockage caused by untimely aging of water accumulation in the dewatering pipe, large-diameter pipes are selected, and an aging backflush process is added to the analysis of each set of samples.

[0036] The outer frame houses a cooling heat block, which houses a water removal pipe. The block is coated with a layer of high-temperature-resistant, waterproof adhesive to prevent condensed water from seeping into the cavity and causing a short circuit in the water removal pipe's heating assembly.

[0037] Peltiers are installed on both sides of the cooling block. The outer frame has two openings, and pure copper heat sink components are installed in close proximity to the Peltiers. The copper heat sink components are exposed and fixed to the outside of the outer frame. The pure copper heat sink assembly includes a pure copper heat sink and a cooling fan. The pure copper heat sink is installed in close proximity to the Peltiers. This improves cooling efficiency and extends the life of the Peltiers, ensuring a stable operating temperature of the refrigerated dewatering trap module between 0°C and -20°C. This reduces the cool-down time after dewatering pipe aging and shortens the analysis cycle.

[0038] The outer frame is an insulation frame, and the gap between the cooling and heat conducting blocks and the outer frame is filled with foam. Filling the gaps within the outer frame with foam improves the overall insulation effect of the module.

[0039] The cooling block and outer frame are composed of two symmetrically spaced halves, bolted together. The compact modular design allows for easy assembly and replacement. The pure copper heat sink is bolted to the outer frame, and the cooling fan is also bolted to the pure copper heat sink. The dewatering pipe is installed within the cooling block using connectors and bolts. The dewatering trap module is designed and operated independently, eliminating the traditional dewatering trap module design. This allows for easy assembly and disassembly, and the dewatering trap and trap modules can be replaced independently.

[0040] The workflow of this utility model:

[0041] 1. During the sampling phase, the refrigeration temperature of the water trap is controlled at about 0 to -20°C, the heating component does not work, and the sample is drawn into the water trap after filtration. Due to the low temperature of the water trap, water vapor condenses and fixes on the surface of the water trap wall.

[0042] 2. During the sample transfer phase, the refrigeration temperature of the water trap is controlled at about 0 to -20°C, the heating component works, the water removal tube is heated to about 20 to 50°C, and the carrier gas is connected to transfer the adsorbed sample in the water removal tube to the capture trap;

[0043] 3. During the aging backflush stage, the refrigeration temperature of the dewatering trap is controlled at around -10 to -20°C, the temperature of the dewatering pipe is raised again by 100 to 150°C, and the reverse carrier gas is connected to backflush the water vapor in the dewatering pipe to prevent water accumulation in the pipe from causing ice blockage.

[0044] The embodiment described above is only a preferred solution of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A low-temperature water trap device for a direct non-methane total hydrocarbon analyzer, comprising an outer frame, characterized in that: The outer frame is an insulation frame, a cooling heat conduction block is arranged inside the outer frame, a water removal pipe is placed inside the cooling heat conduction block, Peltiers are installed on both sides of the cooling heat conduction block, the outer frame has openings on both sides, and pure copper heat dissipation components are tightly installed at the openings on both sides of the outer frame. The pure copper heat dissipation components are installed tightly against the Peltiers, and the pure copper heat dissipation components are exposed and fixed on the outside of the outer frame.

2. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 1, characterized in that: Both ends of the dewatering pipe and the inner surface of the dewatering pipe are respectively coated with an anti-oxidation layer.

3. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 1, characterized in that: The outer side of the refrigeration heat conducting block is coated with a layer of high temperature resistant and waterproof glue.

4. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 1, characterized in that: The gap between the cooling and heat-conducting block and the outer frame is filled with foam glue.

5. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 1, characterized in that: The water pipe is wound with a heating wire.

6. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 1, characterized in that: The pure copper heat dissipation component comprises a pure copper heat sink and a heat dissipation fan, and the pure copper heat sink is installed closely to the Peltier.

7. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 1, characterized in that: The cooling heat conducting block and the Peltier are adhered to each other via heat conducting silicone grease.

8. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 1, characterized in that: The cooling heat conducting block and the outer frame are respectively formed by two symmetrically distributed half modules which are assembled by bolts.

9. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 6, characterized in that: The pure copper heat sink is mounted on the outer side of the outer frame through bolts, and the heat dissipation fan is mounted on the pure copper heat sink through bolts.

10. The low-temperature water removal trap device for a direct non-methane total hydrocarbon analyzer according to claim 1, characterized in that: The water removal pipe is installed in the refrigeration heat conduction block through connecting pieces and bolts.

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