Condenser used for microwave digestion tank and facilitating nitric acid recovery

Abstract

The utility model belongs to the field of detection and analysis instruments, and particularly relates to a microwave digestion tank. A cold water pipe is inserted into a container, and a water valve is mounted at the part, extending out of the container, of the cold water pipe; a liquid discharge pipe is arranged at the bottom of the container; a control valve is mounted on the liquid discharge pipe; an air inlet is formed in the lower position of the side wall of the container and communicated with a bent air inlet pipe, and the end of the air inlet pipe is connected with a digestion tank connector. As the evaporation speed is not high when the microwave digestion tank is used for removing acid, flowing water is not adopted for cooling during water cooling, after the cold water pipe filled with cooling water is filled with water, nitric acid is cooled and recycled by utilizing the temperature difference between the water in the cold water pipe and nitric acid steam, and the recycled nitric acid can be discharged through a bottom valve. As a condenser of the microwave digestion tank is small in size and simple in structure, after a cooling water cold water pipe is filled with water, nitric acid steam is cooled through the water in the cold water pipe, cooling water does not need to be introduced all the time, the water can be changed according to conditions, and the problem of acid expelling of the digestion tank is solved at low cost.

Description

Technical Field

[0001] This utility model belongs to the field of testing and analysis instruments, and specifically relates to microwave digestion vessels. Background Technology

[0002] In food and environmental monitoring, elemental analysis typically employs microwave digestion. This involves weighing the sample into a microwave digestion vessel, adding nitric acid (usually 5-8 mL), sealing the vessel tightly, and heating for digestion. If atomic absorption spectrometry is used for analysis, acid removal is necessary; this involves heating to distill the acid out of the digestion vessel until only 0.5 mL remains. Common physical treatment methods for tail gas generated during nitric acid production include adsorption, condensation, and membrane separation. Adsorption offers advantages such as good treatment efficiency, simple equipment, and low operating costs, but requires regular adsorbent replacement and demands high precision in adsorbent selection and preparation. Condensation is suitable for treating high-concentration, low-temperature tail gas, but requires significant equipment investment and high energy consumption. Membrane separation offers advantages such as good treatment efficiency, simple equipment, and low operating costs, but demands high precision in membrane selection and maintenance. However, the above methods are not well-suited for acid removal using microwave digestion vessels.

[0003] Chinese patent CN113776921A discloses a microwave digestion vessel and an integrated "online" vacuum acid removal system based on this vessel. The system comprises a refrigeration unit, a refrigerant, a circulating pump, a condenser, a receiving bottle, and a neutralization device. The refrigerant is placed in the refrigeration unit, which is connected to the circulating pump. The circulating pump is connected to the condenser, and the receiving bottle is connected to the lower end of the condenser. The vacuum port of the condenser is connected to the neutralization device. The container in the neutralization device contains alkaline solutions of different concentrations to neutralize uncondensed acid vapors and prevent acid vapors from entering the vacuum pump in the vacuum control system, thus affecting its lifespan. The entire acid distillation and neutralization system is a closed system, therefore no acid vapors are emitted into the atmosphere. The entire acid removal process can utilize the residual heat of the vessel after microwave digestion as a heat source, making it an energy-saving and environmentally friendly online vacuum acid removal system that uses neutralization for acid removal.

[0004] In addition, there is no dedicated acid removal device for microwave digestion vessels. Generally, the acid distilled out by heating in the digestion vessel is discharged into the atmosphere through the ventilation device of the fume hood without being recovered. The entire process also corrodes the fume hood, which can easily cause equipment damage and environmental pollution. Utility Model Content

[0005] The purpose of this invention is to solve the problem of acid removal from digestion tanks and to provide a condenser for microwave digestion tanks that facilitates nitric acid recovery. The condenser has a simple structure and allows for the condensation and recovery of acid evaporated during heating in the digestion tank, reducing corrosion damage to ventilation equipment and environmental pollution.

[0006] The technical solution adopted by this utility model to achieve the above objectives is as follows: a condenser for microwave digestion tank to facilitate nitric acid recovery, comprising a container and a cold water pipe, the top of the container being open, the cold water pipe being inserted into the container, and a water valve being installed on the part of the cold water pipe extending out of the container; the bottom of the container having a drain pipe, on which a control valve is installed; and an air inlet located on the lower side wall of the container, the air inlet being connected to a bent air inlet pipe, the end of which being connected to the digestion tank connector.

[0007] The digestion tank connector is a threaded connector, and the digestion tank connector is integrated with the air inlet pipe.

[0008] The cold water pipe is a straight or spherical pipe, with the top closed and placed inside a container, and the bottom extending out of the container and equipped with a water valve.

[0009] The air intake pipe is a V-shaped pipe.

[0010] The opening at the top of the container is tapered inwards.

[0011] Compared with existing acid removal devices, this invention has significant advantages: it adopts the principle of distillation cooling and designs a cooling device that is compatible with microwave digestion vessels. Considering that the commonly used acid for digestion is nitric acid, which has a boiling point below 140°C, water cooling is used to cool and cut the gaseous acid mist into liquid acid for recovery.

[0012] This invention connects the digestion vessel and the condenser with a connector and is sealed with a PTFE gasket. Considering that the evaporation rate is not very fast when the microwave digestion vessel is removing acid, flowing water is not used for cooling during water cooling. After filling the cooling water pipe with water, the nitric acid is cooled and recovered by utilizing the temperature difference between the cooling water and the nitric acid vapor. The recovered nitric acid can be released through the bottom valve.

[0013] Existing condensers are mainly used with Erlenmeyer flasks and round-bottom flasks, employing either air cooling or continuous cooling medium circulation for cooling, and have a relatively large distillation capacity. The condenser of this invention is specifically designed for microwave digestion vessels. Due to the smaller distillation capacity, the condenser is smaller in size. After filling the cooling water pipes with water, the nitric acid vapor is cooled through the water supply, eliminating the need for continuous cooling water circulation. Water can be changed as needed, resulting in low cost and significant effectiveness. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] Figure 2 This is a diagram showing the usage state of this utility model.

[0016] In the diagram: 1. Container; 2. Cold water pipe; 3. Digestion tank connector; 4. Water valve; 5. Control valve; 6. Air inlet pipe; 7. Digestion tank. Detailed Implementation

[0017] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 The condenser shown is for microwave digestion tanks to facilitate nitric acid recovery. It includes a container and a cold water pipe. The top of the container is an inward-curving opening. The cold water pipe 2 is inserted into the container 1 and sealed. Preferably, the cold water pipe is integrated with the container for better sealing. The cold water pipe 1 is a straight pipe with a closed top placed inside the container and a water valve 4 installed at the bottom. The bottom of the container has a drain pipe with a control valve 5 installed on it. There is an air inlet on the lower side wall of the container, which is connected to a bent air inlet pipe 6. The end of the air inlet pipe is connected to a digestion tank connector 3. The digestion tank connector 3 is a threaded connector and is integrated with the air inlet pipe.

[0019] The cold water pipe of this utility model can also be a spherical pipe, with the top closed and placed inside a container, and the bottom extending out of the container and equipped with a water valve.

[0020] The intake pipe 6 of this utility model is a V-shaped pipe as shown in the figure. Other bending shapes can also be used to ensure that the gas flow rate is slow and there is enough time for cooling. The cooling equipment is small in size and can achieve excellent acid recovery effect.

[0021] When using Figure 2 As shown, the digestion vessel connector 3 is connected to the digestion vessel 7 and sealed with a PTFE gasket. Considering that the evaporation rate is not very fast during the acid removal process in the microwave digestion vessel, flowing water is not used for cooling. After filling the cooling water pipe with water, the nitric acid evaporated in the digestion vessel enters the bottom of the container through the inlet pipe. Utilizing the temperature difference between the cooling water and the nitric acid vapor, the nitric acid is cooled and recovered. The recovered nitric acid can be released through the control valve at the bottom of the container. If the cooling water effect is not obvious, the cooling water can be replaced through the water valve.

[0022] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in this utility model, based on the technical solution and inventive concept of this utility model, should be included within the protection scope of this utility model.

Claims

1. A condenser for microwave digestion vessels to facilitate nitric acid recovery, characterized in that, It includes a container and a cold water pipe. The cold water pipe is inserted into the container, and a water valve is installed on the part of the cold water pipe that extends out of the container. The bottom of the container has a drain pipe with a control valve installed on it. There is an air inlet on the lower side wall of the container, which is connected to a bent air inlet pipe. The end of the air inlet pipe is connected to the digestion tank connector.

2. A condenser for microwave digestion tanks to facilitate nitric acid recovery according to claim 1, characterized in that, The digester connector is a threaded connector, which is integrated with the air inlet pipe.

3. A condenser for microwave digestion vessels to facilitate nitric acid recovery according to claim 1, characterized in that, The cold water pipe is a straight or spherical pipe, with the top closed and placed inside a container, and the bottom extending out of the container and equipped with a water valve.

4. A condenser for microwave digestion tanks to facilitate nitric acid recovery according to claim 1, characterized in that, The air intake pipe is a V-shaped pipe.

5. A condenser for microwave digestion vessels to facilitate nitric acid recovery according to claim 1, characterized in that, The container opening is tapered inwards.

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