Guangxi visual nitrogen blowing instrument dry heating

Guangxi visual nitrogen blowing instrument dry heating

Nitrogen blowing apparatus is used for sample preparation in gas chromatography, liquid chromatography, and mass spectrometry analysis. It uses approved technology to concentrate the sample by blowing nitrogen into the surface of the heated sample. This method has the characteristics of time-saving, convenient operation, and easy control, and can quickly obtain the expected results. This technology uses solid-phase extraction pretreatment technology instead of traditional liquid-phase extraction and chromatography techniques, enabling rapid separation and purification of samples. Replacing the commonly used rotary evaporator with nitrogen blowing for concentration greatly shortens the analysis time.

The nitrogen blowing instrument is mainly used for concentration, purification, and detection of samples. According to the heating tank structure of the instrument, it can be divided into square and circular nitrogen blowing instruments; According to the heating method of the instrument, it can be divided into metal dry bath and water bath nitrogen blowing instruments. The heating carrier of metal dry bath includes aluminum block hole dry bath, aluminum bead bath, and fine yellow sand bath, among which aluminum bead bath is used.

3. Blowing method and synthesis standard

3.1. Blowing method

3.1.1. Blind plates must be added to block the connection parts with each section, and they should be removed one by one when used for blowing to prevent gases with debris from entering other processes. The blowing should be carried out in the order of (first) the main pipe, and then the branch pipes.

3.1.2. During the blowing process, the guide pipe, instrument pressure pipe, analysis sampling pipe, etc. should be cleaned to prevent blind spots;

3.1.3. Purging is carried out continuously at each discharge outlet. And continuously strike the pipeline with a wooden hammer, especially focusing on welding seams and dead corners, but not damaging the pipeline until it is blown and qualified;

3.1.4. When blowing, air should be slowly supplied to the pipeline. When there is air discharged from the inspection outlet, the air volume can be gradually increased to the required amount for blowing to prevent system overpressure caused by incorrect valves, blind plates, etc;

3.2. Qualification criteria

Whether each section of pipeline or system is qualified for blowing should be jointly inspected by production and installation personnel. When the exhaust is visually clean and free of impurities, use a white cloth or a target plate coated with white lead oil to inspect the exhaust outlet. If there is no rust, dust, moisture, other dirt, or pitting within five minutes, it is considered to be qualified for blowing.

3、 Requirements for blowing and sweeping

1. Blowing range

All N2 pipeline networks of the urea plant are detailed in the attached N2 pipeline network diagram.

2. Having the conditions

1. 2.1. The installation of the N2 pipeline network system has been completed and the strength pressure test has been passed; The main pipe of N2 pipeline network has been blown and qualified before entering the urea boundary area.

2.2. After removing the internal components such as orifice plates and rotor flow meters from the pipeline, install and reset them. The root valves of pressure gauges, liquid level gauges, and pressure gauges should be closed;

2.3. Blind plates have been installed on prohibited equipment, pipelines, pumps, valves, etc;

2.4. The construction and installation of temporary piping, valves, etc. for blowing purposes have been completed;

2.5. Process pipelines that require blowing are generally not insulated temporarily, as wooden hammers are needed to strike the outer wall of the pipeline during blowing;

2.6. The compressor providing the air source for blowing has been put into operation and the utility project meets the continuous gas supply conditions of the compressor;

2.7. Draw a purging process diagram, which should indicate the purging program, flow direction, exhaust port, temporary pipelines, temporary valves, and the contents to be processed in advance;

2.8. If working at night, the lighting conditions on site should be considered, and temporary lighting should be arranged in advance if necessary.

2.9. Prepare a blowing record form signed by representatives from the user, construction unit, and commissioning execution department for filling out during blowing;

2.10. Fire and gas protection equipment, combustible gas alarm systems, and radioactive material protection facilities have been constructed according to the design and are in good condition.

2.11. The detection points for dust, toxicity, and noise in the position have been determined.

2.12. The job responsibility system has been formulated and improved.

2.13. The test plan, operating procedures, and operating methods have been completed and distributed to the production test personnel.

2.14. The production and testing personnel have received training and passed the assessment, and hold a work permit.

2.15. Familiarize oneself with PID diagrams and test plans, master test procedures, and understand the key operating points and safety precautions during the blowing process.

2.16. Prepare the necessary spare parts and components for the test drive.

Technical Specifications:

Guangxi visual nitrogen blowing instrument dry heating

Purpose and Technical Requirements of Purging

1. Purpose:

1.1. Check if the N2 pipeline network is unobstructed. Check whether there are any omissions in the pipeline network and piping; Check for leaks at the interfaces of flanges, valves, instruments, and packing glands in the pipeline network.

1.2. Due to residual debris during pipeline construction and equipment manufacturing processes, such as welding slag deposits, oxide scales on the inner surfaces of pipelines and equipment, particulate matter, mud and sand debris attached to their inner walls, grease, welding slag, and rust, etc. Before the process pipelines and equipment are put into use, they must be thoroughly cleaned to ensure their cleanliness and avoid blockages; Damaged machines, valves, and instruments; Staining catalysts and chemical solutions, affecting product quality, ensuring smooth chemical feeding and safe production.

2. Technical requirements:

2.1. 0.7Mpa（A）、 25 ℃ N2 is used for blowing and sweeping eachN2Ethernet cable;

2.2. The airflow velocity for blowing is ≥ 30m/s.

2.3. During blowing, all instrument measuring components installed on the pipeline (such as flow meters, orifice plates, etc.) should be removed to prevent damage to the instrument components caused by the flow of dirt during blowing. At the same time, protective measures should be taken for the regulating valve;

2.4. When blowing, blind plates must be added to the inlet side of equipment such as heat exchangers and towers. Only after the upstream blowing is qualified can the equipment be entered. Generally, the heat exchanger body does not participate in air blowing;

2.5. In principle, the regulating valve in the system should not be used as the control valve for blowing. If it is necessary to control the blowing air volume of the system, a temporary blowing valve should be selected. During blowing, the connection between the safety valve and the pipeline should be disconnected, and a blind plate or baffle should be added to prevent dirt and debris from blowing to the bottom of the valve, causing wear on the sealing surface at the bottom of the safety valve;

2.6. When blowing the system, all instrument pressure pipelines should be opened for blowing, and should be blown again in the comprehensive airtightness test of the system;

2.7. All vent flare pipelines and drainage pipelines should be purged after the main pipe connected to them. The drainage pipes of the equipment casing, as well as the outlet pipes and valves of the liquid level meter and flow meter, must be purged;

During the blowing process, only after the upstream system is qualified, can the blowing air enter the downstream system through the normal process;

2.9. For equipment with a pipeline diameter greater than 500mm and a manhole, manual cleaning is required before blowing, and any internal components that may hinder the blowing process must be removed;

2.10. All tanks, towers, reactors, and other containers should be manually cleaned and their corresponding internal components reset after the system has passed the blowdown inspection;

2.11. Check that all pipeline clamps in the system are installed and properly equipped to ensure that there is no pipeline vibration during the blowing process.

If there is a filter on the pipeline or at the inlet of the pump, the filter screen should be removed or the filter should be dismantled

2.13. When blowing, except for non-ferrous metal pipes, use a hammer (wooden hammer for stainless steel pipes) to strike the pipes. Focus on striking the welds, dead corners, and pipe bottoms, but do not damage the pipes;

Comparison of Heating Methods between Dry Nitrogen Blowers and Water Bath Nitrogen Blowers:
1. Water bath heating usually involves placing the test tube to be heated in a beaker filled with water, heating the water with a heat source, and then transferring the heat to the test tube. It can be seen as an indirect heating process, different from dry direct contact heating with a heat source; In addition, during the water bath heating process, a thermometer can be inserted into the water in the beaker to observe the water temperature in real time, which can effectively control the temperature of the water. The dry heating method is difficult to achieve real-time temperature control.
During the heating process of the water bath, the test tube is immersed in beaker water, and all parts are heated evenly; The dry heating method usually heats the bottom of the test tube more than the middle and upper parts.
3. Water bath heating has slow heating and cooling, and the heating temperature does not exceed 100 ℃, making it a "mild" heating method; Dry heating method has fast heating and cooling, and the heating temperature can reach up to about 180 ℃. It can be considered as a "rapid fire" heating method, and the two heating methods are suitable for different material samples.
4. Some organic substances should not come into contact with open flames, so the heating process must be carried out in a water bath; Some organic metal reagents should not come into contact with water, and water bath heating will produce a large amount of water vapor, so water bath heating cannot be used.