Pressure reducing valve rear regulating nitrogen sealing valve

Product Introduction

ZZDQ nitrogen sealing device is composed ofZZDG-16B pressure reducing valveAdjust the nitrogen sealing valveInstant nitrogen supply valveComposed of ZZDX-16K nitrogen relief valve, it is a self operated micro pressure control system independently developed and researched by our factory. It is mainly used to maintain a constant pressure of the protective gas (usually nitrogen) at the top of the container, to avoid direct contact between the materials in the container and air, prevent material volatilization, oxidation, and ensure the safety of the container. This product has the characteristics of energy saving, sensitive action, reliable operation, and convenient operation and maintenance. Widely used in industries such as petroleum and chemical.
The nitrogen supply device consists of a commander and a main valve; The nitrogen release device consists of a pressure open micro pressure regulating valve with internal feedback. The nitrogen pressure is generally set to 100mmH2O (i.e. 1KPa) and precisely controlled through a nitrogen sealing device.

When the inlet valve of the storage tank is opened and materials are added to the tank, the liquid level rises, the volume of the gas phase decreases, and the pressure increases. When the pressure inside the tank rises above the set pressure of the nitrogen release valve of the nitrogen release device, the nitrogen release device opens and releases nitrogen gas to the outside, causing the pressure inside the tank to decrease. When the pressure drops to the set point of the nitrogen release device, the nitrogen release valve automatically closes.
When the liquid outlet valve of the storage tank is opened and the user releases the material, the liquid level drops, the volume of the gas phase increases, and the pressure inside the tank decreases. The nitrogen supply valve of the nitrogen supply device opens, injecting nitrogen into the storage tank to increase the pressure inside the tank. When the pressure inside the tank rises to the point where the nitrogen supply valve automatically closes.

Advantages:
Conservation and Environmental Protection: No need for external energy, mechanical automatic pressure regulation and control.
Simplified system: No need for external secondary instrument control, direct action type, simple system maintenance cost is low.
Explosion proof safety: Used for working in environments without power or gas sources, there is no hidden danger of external energy sources.
Easy to operate: When setting or adjusting pressure, it can be synchronized during operation. Just adjust the pressure regulating spring to achieve it.
Reliable quality: low voice, maintenance free, reliable performance, pressure balancing function, high sensitivity.

Working principle of nitrogen supply device

ZZDG-16BPressure reducing valve rear regulating nitrogen sealing valveThe structure of the nitrogen supply valve in the nitrogen supply device is shown in the right figure. The medium at the pressure point located on the top of the tank is introduced into the detection mechanism (7) through a pressure pipe. The medium generates a force on the detection element that is balanced with the spring (8) and pre tension force. When the pressure inside the tank drops below the set point of the nitrogen supply device, the balance is disrupted, causing the commander valve core (6) to open, allowing the gas in front of the valve to pass through the pressure reducing valve (5), throttle valve (4), and enter the upper and lower membrane chambers of the main valve actuator (3). The main opening valve core (2) is then opened to fill the tank with nitrogen gas; When the pressure inside the tank rises to the set point of the nitrogen supply device, due to the preset spring force, the controller valve core (6) is closed, and due to the spring action in the main valve actuator, the main valve is closed, stopping the nitrogen supply.

Working principle of nitrogen release device

The structure of the nitrogen release valve of the nitrogen release device is shown in the right figure. The device adopts an internal feedback structure, and the medium directly enters the detection mechanism (2) through the valve cover. The medium generates a force on the detection element that is balanced with the pre tightening force of the preset spring (3). When the pressure inside the tank rises above the pressure set point of the nitrogen release device, the balance is disrupted, causing the valve core (1) to move upward, open the valve, and release nitrogen gas to the outside; When the pressure inside the tank drops to the set point of the nitrogen release device, the valve is closed due to the preset spring force.

Instructions

The general nitrogen supply pressure is between 3 × 10 ^ 5-10 × 10 ^ 5Pa
The breathing valve on the top of the tank only serves a safety purpose and does not work under normal circumstances when the main valve fails, causing the pressure inside the tank to be too high or too low
The nitrogen release valve is installed on the top of the tank, and its diameter is generally the same as that of the inlet valve*
The pressure setting point of the general nitrogen release valve is slightly higher than that of the nitrogen supply valve to avoid frequent operation of the nitrogen supply and release devices, waste of nitrogen gas, and affecting the service life of the equipment

Technical parameters and performance indicators:

1. Nitrogen supply device (Table 1)

The pressure regulation range of the nitrogen supply device is shown in Table 2 (Table 2)

The external dimensions of the nitrogen supply device are shown in Table 3. Unit: mm

Note: 1) The standard flange connection form PN16 is convex, and the connection size for cast iron flanges is in accordance with GB4216.5-84. For cast steel flanges, it is in accordance with GB9113-2000 and JB/T-94. The valve body flange and flange end face distance can also be manufactured according to user standards, such as ANSI, JIS, DIN, etc.

2) Take over and configure according to user needs

The nitrogen release device is shown in Table 4 (Table 4)

The pressure regulation range of the nitrogen release device is shown in Table 5 (Table 5)

Table 6 Dimensions and Weight（Table 6) Unit: mm

Main component materials:

◇　阀体： ZG230-450、ZG1Cr18Ni9

Valve components: 1Cr18Ni9Ti

◇ Film cover: A3, 1Cr18Ni9Ti

◇ Diaphragm: clip reinforced polyester fabric rubber, fluororubber

◇　弹簧： 60Si2Mn、1Cr18Ni9Ti

*According to user requirements, other grades of materials can be used for the valve body, valve internals, and diaphragm cover.

Equipment ordering instructions:

◇ Device name and model

◇ Pressure setting point for sputum supply and nitrogen release device

◇ nominal diameter DN (mm) of sputum supply and nitrogen release device

◇ Media name

◇ Nominal pressure PN (MPa) of sputum supply and nitrogen release device

◇ Work pressure and adjustment range

◇ Rated flow coefficient Kv of sputum supply and nitrogen release device

Valve body, valve internals, and packing materials

◇ Inherent flow characteristics of sputum supply and nitrogen release devices

Other special requirements

Dimensions and standards:

• Connection method: flange, thread, welding

• Flange end distance: GB/T, 9113

• Flange standards: JB/T79.1-1994, HG/T20592-2009, ANSI, GB/T9113-2000

• Flange sealing surface type: RF

• Execution mechanism gas signal interface: M16 × 1.5 (customized specifications may vary depending on the operating conditions, please confirm when placing the order)

HXF-I0 all-weather fire-resistant breathing valveInstallation and precautions:
The breathing valve can also be used in conjunction with an air seal system. Commonly used gas seals include nitrogen, fuel gas, etc. When the material inside the tank is pumped out or when the gas inside the tank condenses and shrinks due to a decrease in temperature, a gas seal should be added to prevent air from entering the tank. When the pressure inside the tank increases due to feeding or temperature rise, the breathing valve automatically opens and releases the overpressure gas into the atmosphere. When the pressure inside the tank is lower than atmospheric pressure and the sealing system cannot work properly, the vacuum valve inside the breathing valve opens, and air enters the tank to ensure that the storage tank is not damaged. When using a breathing valve and gas seal system together, the following should be noted:
A breathing valve is a ventilation device fixed on the top of a storage tank to ensure the normal pressure inside the tank, prevent damage to the tank caused by overpressure or vacuum, and reduce the loss of liquid evaporation inside the tank.
According to the Chinese "Fire Protection Design Code for Petrochemical Industry" (GB50160-92), "Fixed top tanks for Class A and Class B liquids should be equipped with flame arresters and breathing valves.

Daily maintenance and upkeep:
（1） Check and remove foreign objects from the valve
Whether it is a nitrogen sealed valve or other types of valves, if there are foreign objects inside the valve, it will inevitably affect the normal operation and stability of the valve. Therefore, during the maintenance process, we need to pay attention to the skillful inspection of the valve and pipeline for dirt, welding slag, and rust. If there are any, corresponding measures need to be taken immediately to remove them. If foreign objects are produced in the pipeline, it is necessary to consider installing some filtering devices upstream of the valve. The removal of foreign objects must be done properly, otherwise it may cause wear and tear on the sealing surface, valve core, and valve seat of the valve, which will affect the stability of the valve operation.

（2） Regularly inspect the gas source and power supply
In some cases, the gas source is also crucial for the operation of nitrogen sealed valves, such as the membrane chamber and other related components of the valve. Sometimes, if there should be no oil contamination but impurities or moisture are present, a series of failures may occur to its components and accessories. Therefore, it is necessary to ensure the cleanliness and dryness of the valve power supply and gas source.

（3） Stress management
After valve installation, due to non-standard installation and other external factors such as stress caused by pipeline temperature, problems during installation, and environmental impacts, etc., if these forces act on the valve or its main pipeline, they will inevitably have an improper impact on the valve's operation and performance, especially in severe cases, it may also cause sealing problems between the valve and pipeline. Therefore, when inspecting and maintaining the valve, we must ensure the elimination of similar stresses.

（4） Storage and transportation
Valves will inevitably go through some vehicle transportation before leaving the factory for use. Before leaving the factory for transportation, the manufacturer needs to consider the fixing and shock absorption arrangements for the valve packaging. For example, some valve components that are easily damaged, such as protruding parts and some instruments on the valve, can be separated from some joints for packaging and transportation. When assembling, they can be assembled according to the manufacturer's instructions. The main valve body is fixed in fixed packaging, which can effectively avoid damage caused by looseness and vibration during long-distance transportation.
For the storage of valves, which may seem simple, there are actually many technical requirements. We need to pay attention to the fact that during the storage process, especially for long-term storage, we need to be careful not to use sensitive parts of the valve such as the valve stem, instruments, and precision components as load-bearing when supporting. The storage and preservation environment should meet the requirements stated in the manufacturer's instructions, especially in the storage area, attention should be paid to avoiding wind, rain, sand, dust, etc., finding a suitable place, and also paying attention to humidity control in the air.

（5） Regular refueling inspection of valves
Valves are equally precise components. Remember to use plastic sleeves or other protective items around the valve stem to protect the packing box and guide parts in dusty environments. Especially in situations where corrosive gases are present, special protective measures need to be taken. Remember to readjust the packing and oil injector after short-term use, and during the inspection process, remember to protect the surface of precision parts. When disassembling the valve, use tools and standard disassembly procedures.

（6） Inspection of support situation
The position of the valve during installation is very important, especially for nitrogen sealed valves. The stroke direction of the valve stem and the actuator of the valve body are usually on the same vertical plane during installation. If the movement direction of the valve stem has a certain inclination angle with the horizontal plane, the actuator should be supported. The advantage of doing so is that every component of the valve can be in a relatively normal working state. At this time, the support point and direction of installation are very important. If no support point is added or there are problems with the support point, it may cause some possible problems in subsequent use. Therefore, it is necessary to check it regularly. Generally, manufacturers have different requirements for this, and it is more appropriate to check it every two months or so.

（7） Maintenance and inspection of operational safety conditions
The safety inspection during operation is mainly one of the prerequisites for ensuring the safe operation of nitrogen sealed valves, especially in some explosive and dangerous places where the operation of valves needs to be stable. It is necessary to ensure the safety and reliability of valve related components. The inspection of valve components, such as whether the sealing parts are loose, the power supply situation, and the inspection of the circuit, needs to be sufficient to ensure the safe operation of nitrogen sealed valves.

Lekong Instrument shares safety measures for methanol tank area:

1. Due to the high temperature in summer and the fact that the refined methanol and refined methanol products produced by methanol synthesis and distillation units are both at 30-40 degrees Celsius, the temperature may be higher when wax or scaling occurs in the methanol cooler heat exchanger. Therefore, it is necessary to install sprinkler water cooling and cooling devices to reduce the release of methanol vapor, reduce the risk of fire, and also play a role in extinguishing fires in case of fire. The sprinkler system is generally connected to the pipeline network for continuous water supply, and a reservoir is also set up for emergency needs. Generally, the required storage capacity is 2 hours.
2. Breather valve: Due to the volatility of methanol and the pressure of methanol entering the tank from synthesis and distillation, some low boiling point gases are dissolved. As the tank is designed for constant pressure, a breather valve must be installed on each tank to ensure that the low boiling point gases dissolved in methanol flash out, keeping the tank at atmospheric pressure.
3. The nitrogen seal is installed in the methanol storage tank to prevent the formation of explosive mixtures when air enters the tank. When the tank is fed outward, the amount of liquid in the tank decreases. In winter, when the tank is sealed, the temperature of methanol in the tank gradually decreases, and the system pressure also decreases. If there is no nitrogen seal, negative pressure will be formed to suck in air, forming explosive mixtures and posing a risk of explosion.

What protective measures should be taken to deal with methanol leakage accidents?
Methanol is a flammable and volatile liquid that can be ignited by heating, sparks, or open flames, causing a fire; Its vapor can form explosive mixtures with air, with an explosive limit of 6.0% to 36.5%, making it prone to explosions.
When the human body comes into contact with methanol, it can be absorbed through the respiratory and digestive tracts, and partially absorbed by the skin, with obvious accumulation characteristics. Methanol can cause systemic diseases in the human body, mainly including central nervous system damage, eye damage, and metabolic acidosis. During the accident handling process, the following measures can be taken on site:
Firstly, you need to call the emergency number on the transportation label or the local fire emergency number. Take emergency preventive measures, carry out on-site evacuation work, evacuate unrelated personnel, and stay in the upwind area. Do not enter low-lying areas. Isolation zones should be set up around the leakage area. If only leakage occurs, the isolation distance should be at least 50 meters. If a fire occurs and there are storage tanks, tank trucks, or tank trucks on site, the isolation distance should be at least 800 meters.
When a storage tank or truck catches fire, try to extinguish it as far away as possible or use remote-controlled water guns or cannons to put it out; Cool the container containing hazardous materials with a large amount of tap water until the fire is extinguished. If the safety valve of the container makes a sound or the tank changes color, evacuate quickly and stay away from the tank engulfed by the fire.
When there is a spill or leakage, rescue personnel should wear fully enclosed protective clothing to handle the spill or leakage that is not on fire; The equipment used for handling fire sources must be grounded; Do not come into contact with or pass through leaked materials; Prevent leakage from entering drainage ditches, sewers, etc., and set up an isolation zone in front of the leakage to wait for treatment.