COD digestion instrument acid mist recovery device

Abstract

The utility model relates to environmental detection laboratory equipment technical field especially relates to a kind of COD digestion instrument acid mist recovery device, including the acid mist gas-collecting hood being set on the reflux pipe of COD digestion instrument, acid mist neutralizing device, diaphragm vacuum pump and control switch;Acid mist neutralizing device includes primary neutralizing bottle and secondary neutralizing bottle, primary neutralizing bottle and secondary neutralizing bottle are communicated by first pipeline;First alkaline neutralizing liquid is contained in primary neutralizing bottle, pure water or second alkaline neutralizing liquid is contained in secondary neutralizing bottle;The gas outlet of acid mist gas-collecting hood is communicated with primary neutralizing bottle by second pipeline;Diaphragm vacuum pump is communicated with the top space of secondary neutralizing bottle by third pipeline;Control switch is electrically connected with diaphragm vacuum pump, the utility model is collected by negative pressure suction, and the sulfuric acid mist that the reflux pipe of COD digestion instrument disperses is oriented, and is absorbed by two levels, and acid mist is efficiently removed, effectively solve the problem that acid mist corrodes equipment and harm experiment personnel health.

Description

Technical Field

[0001] This utility model relates to the field of environmental testing laboratory equipment technology, and in particular to an acid mist recovery device for a COD digester. Background Technology

[0002] In environmental testing laboratories, the determination of chemical oxygen demand (COD) is a routine and important water quality analysis item. During the determination process, the sample needs to be digested at high temperature in the presence of strong acid (usually concentrated sulfuric acid) and a catalyst. During this process, some sulfuric acid will volatilize along with water vapor, forming highly corrosive sulfuric acid mist, which will escape into the laboratory environment from the reflux tube opening of the COD digester.

[0003] Currently, laboratory treatment of such waste gases mainly relies on general laboratory ventilation systems, such as fume hoods. Fume hoods capture harmful gases generated during operation by generating directional airflow and transport them to centralized waste gas treatment devices on the roof for processing. However, this method has significant drawbacks in treating sulfuric acid mist. First, sulfuric acid mist is much denser than air. When transported in horizontal or vertical pipes, it easily condenses and adheres to the inner walls of the pipes, fume hoods, and fan blades, causing severe corrosion of these components, shortening equipment lifespan, and posing safety hazards. Second, due to its high density, acid mist is difficult to completely capture and transport to a distant treatment terminal by the airflow of the fume hood, resulting in some acid mist escaping within the laboratory, directly harming the respiratory health of laboratory personnel and potentially corroding precision instruments and equipment. Therefore, there is an urgent need for an acid mist recovery device capable of targeted and direct treatment of individual COD digesters, addressing the problem of acid mist escape at its source. Utility Model Content

[0004] The purpose of this invention is to provide an acid mist recovery device for a COD digester to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: an acid mist recovery device for a COD digester, comprising an acid mist collection hood, an acid mist neutralization device, a diaphragm vacuum pump, and a control switch, all positioned above the reflux pipe of the COD digester; the acid mist neutralization device includes a primary neutralization bottle and a secondary neutralization bottle, which are connected by a first pipeline, and both are sealed containers; the primary neutralization bottle contains a first alkaline neutralizing solution, and the secondary neutralization bottle contains pure water or a second alkaline neutralizing solution; the outlet of the acid mist collection hood is connected to the primary neutralization bottle via a second pipeline, and the outlet end of the second pipeline extends below the surface of the first alkaline neutralizing solution; the diaphragm vacuum pump is connected to the top space of the secondary neutralization bottle via a third pipeline; and the control switch is electrically connected to the diaphragm vacuum pump.

[0006] Preferably, the acid mist collection hood is funnel-shaped, with the large-diameter end of the acid mist collection hood facing the reflux pipe opening of the COD digester, and the small-diameter end connected to the second pipeline.

[0007] Preferably, the first alkaline neutralizing solution is a sodium hydroxide aqueous solution with a concentration of 0.05-0.5 mol / L; when the secondary neutralization bottle contains a second alkaline neutralizing solution, the second alkaline neutralizing solution is a sodium hydroxide aqueous solution with a concentration of 0.01 mol / L.

[0008] Preferably, the first pipeline, the second pipeline and the third pipeline are all made of corrosion-resistant materials.

[0009] Preferably, the volume of the first alkaline neutralizing solution accounts for 60-80% of the volume of the first-stage neutralizing bottle, and the volume of the liquid in the second-stage neutralizing bottle accounts for 60-80% of the volume of the second-stage neutralizing bottle.

[0010] Compared with existing technologies, this invention provides an acid mist recovery device for a COD digester, which has the following beneficial effects: This invention achieves active and directional collection of escaping acid mist by setting an acid mist collection hood directly above the reflux pipe of the COD digester and driving it with a stable negative pressure provided by a diaphragm vacuum pump, effectively preventing the spread of acid mist in the laboratory environment from the source. Employing a two-stage series-connected sealed neutralization device, the acid mist gas is first introduced into a primary neutralization bottle containing a concentrated alkaline solution for deep neutralization, and then enters a secondary neutralization bottle containing pure water or dilute alkaline solution for secondary absorption and purification, ensuring efficient acid mist removal and resulting in clean and harmless exhaust gas. The entire device is designed for a single instrument, is easy to install, and does not rely on a large and easily corroded laboratory ventilation duct system. This not only significantly reduces the risk of corrosion to public ventilation facilities and saves maintenance costs, but also directly protects the health and safety of laboratory personnel, providing a localized, efficient, and reliable acid mist treatment solution for the laboratory. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of this utility model.

[0012] Explanation of reference numerals in the attached diagram: 1. COD digester; 2. Acid mist collection hood; 21. Second pipeline; 3. Acid mist neutralization device; 31. First neutralization bottle; 32. Second neutralization bottle; 33. First pipeline; 4. Diaphragm vacuum pump; 41. Third pipeline; 5. Control switch. Detailed Implementation

[0013] The technical solutions of the present utility model will now be described with reference to the accompanying drawings in the embodiments of the present utility model: like Figure 1As shown, this utility model provides an acid mist recovery device for a COD digester, which addresses the problem that existing laboratory ventilation systems cannot effectively handle sulfuric acid mist emitted during COD digestion, and proposes a targeted, efficient, and independent solution. This device achieves source capture and harmless treatment of acid mist through a combination of negative pressure suction and two-stage chemical neutralization.

[0014] This device includes an acid mist collection hood 2 located above the reflux pipe of the COD digester 1, an acid mist neutralization device 3, a diaphragm vacuum pump 4, and a control switch 5. The COD digester 1 is model HL12.

[0015] The acid mist neutralization device 3 includes a primary neutralization bottle 31 and a secondary neutralization bottle 32, which are connected in series via a first pipe 33. One end of the first pipe 33 is connected to the top space of the primary neutralization bottle 31, and the other end extends below the liquid surface of the secondary neutralization bottle 32. Both the primary and secondary neutralization bottles 31 and 32 are sealed containers to ensure airtightness. The primary neutralization bottle 31 contains a first alkaline neutralizing solution, which is a sodium hydroxide aqueous solution with a concentration of 0.05-0.5 mol / L. This concentration range ensures a rapid and complete neutralization reaction with sulfuric acid, producing neutral sodium sulfate and water.

[0016] The outlet of the acid mist collection hood 2 is connected to the first-stage neutralization bottle 31 via the second pipe 21, and the outlet end of the second pipe 21 extends below the surface of the first alkaline neutralizing liquid. The volume of the first alkaline neutralizing liquid occupies 60-80% of the volume of the first-stage neutralization bottle 31. This liquid level ensures that the outlet end of the second pipe 21 has sufficient immersion depth, allowing the gas to be fully broken into fine bubbles and increasing the gas-liquid contact area; it also provides sufficient top space for the gas flow to prevent the liquid from being drawn into the next stage.

[0017] The secondary neutralization bottle 32 contains pure water or a second alkaline neutralizing solution with a lower concentration. When the secondary neutralization bottle 32 contains the second alkaline neutralizing solution, the second alkaline neutralizing solution is a 0.01 mol / L sodium hydroxide aqueous solution. The volume of the liquid in the secondary neutralization bottle 32 occupies 60-80% of the bottle's volume. Its main function is to act as a safety barrier, further absorbing and removing trace amounts of acidic gas or alkaline droplets that may be carried over from the primary neutralization bottle 31, ensuring the purity of the final emitted gas.

[0018] The acid mist collection hood 2 is funnel-shaped, with its larger diameter end facing the reflux pipe opening of the COD digester 1 to ensure that the acid mist escaping from the reflux pipe is captured by the hood to the maximum extent. The edge of the larger diameter end can be designed as an inward-curving flange to reduce external airflow interference and enhance collection efficiency. The smaller diameter end of the acid mist collection hood 2 connects to the second pipeline 21. The non-contact design between the acid mist collection hood 2 and the COD digester 1 ensures the normal operation of the original equipment while avoiding potential contamination or damage from contact.

[0019] The diaphragm vacuum pump 4, model AP-01D, is connected to the top space of the secondary neutralization bottle 32 via the third pipeline 41. When the diaphragm vacuum pump 4 is working, it creates a stable negative pressure (vacuum) environment throughout the pipeline system. This negative pressure is sequentially transmitted to the secondary neutralization bottle 32 and the primary neutralization bottle 31, ultimately generating a continuous suction force at the inlet of the acid mist collection hood 2, actively drawing the acid mist into the acid mist neutralization device.

[0020] Control switch 5 is electrically connected to diaphragm vacuum pump 4 and is used to control the start and stop of the entire device, making it easy to operate.

[0021] The first pipeline 33, the second pipeline 21, and the third pipeline 41 are all made of corrosion-resistant materials, such as polytetrafluoroethylene (PTFE), silicone, or other acid and alkali resistant polymers. These materials can withstand the corrosion of sulfuric acid mist and sodium hydroxide solution for a long time, ensuring the service life and reliability of the equipment.

[0022] Workflow and Principle: When the COD digester 1 starts working and generates sulfuric acid mist, the operator activates the diaphragm vacuum pump 4 via control switch 5. The negative pressure generated by the diaphragm vacuum pump 4 creates a directional airflow below the acid mist collection hood 2, capturing the escaping sulfuric acid mist. The acid mist, carried by the airflow, enters the sodium hydroxide solution in the first-stage neutralization bottle 31 through the second pipeline 21, rising as bubbles. During this process, sulfuric acid and sodium hydroxide undergo a rapid neutralization reaction, producing sodium sulfate and water, removing most of the acid mist. The gas after the first-stage neutralization (which may carry a very small amount of unreacted gaseous molecules) then enters the second-stage neutralization bottle 32 through the first pipeline 33, where residual components are reabsorbed by the pure water or the second alkaline neutralizing solution. The clean, harmless gas, after two stages of treatment, is finally discharged into the atmosphere by the diaphragm vacuum pump 4 through the third pipeline 41, thus completing the efficient and safe recovery and treatment of acid mist from the COD digester.

[0023] The above embodiments are merely some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

Claims

1. An acid mist recovery device for a COD digester, characterized in that: The system includes an acid mist collection hood (2) installed above the reflux pipe of the COD digester (1), an acid mist neutralization device (3), a diaphragm vacuum pump (4), and a control switch (5); the acid mist neutralization device (3) includes a primary neutralization bottle (31) and a secondary neutralization bottle (32), which are connected by a first pipeline (33), and both the primary neutralization bottle (31) and the secondary neutralization bottle (32) are sealed containers; the primary neutralization bottle (31) contains a first alkaline neutralizing solution, and the secondary neutralization bottle (32) contains pure water or a second alkaline neutralizing solution; The outlet of the acid mist collection hood (2) is connected to the first-stage neutralization bottle (31) through the second pipeline (21), and the outlet end of the second pipeline (21) extends below the liquid surface of the first alkaline neutralization liquid; the diaphragm vacuum pump (4) is connected to the top space of the second-stage neutralization bottle (32) through the third pipeline (41); the control switch (5) is electrically connected to the diaphragm vacuum pump (4).

2. The acid mist recovery device for a COD digester according to claim 1, characterized in that: The acid mist collection hood (2) is funnel-shaped, with the large-diameter end of the acid mist collection hood (2) facing the reflux pipe opening of the COD digester (1), and the small-diameter end connected to the second pipeline (21).

3. The acid mist recovery device for a COD digester according to claim 1, characterized in that: The first alkaline neutralizing solution is a sodium hydroxide aqueous solution with a concentration of 0.05-0.5 mol / L; when the secondary neutralizing bottle (32) contains a second alkaline neutralizing solution, the second alkaline neutralizing solution is a sodium hydroxide aqueous solution with a concentration of 0.01 mol / L.

4. The acid mist recovery device for a COD digester according to claim 1, characterized in that: The first pipeline (33), the second pipeline (21) and the third pipeline (41) are all made of corrosion-resistant materials.

5. The acid mist recovery device for a COD digester according to claim 1, characterized in that: The volume of the first alkaline neutralizing liquid accounts for 60-80% of the volume of the first neutralizing bottle (31), and the volume of the liquid in the second neutralizing bottle (32) accounts for 60-80% of the volume of the second neutralizing bottle (32).

Images