Nitrogen production by pressure swing adsorption (P.S.A) is an advanced gas separation technology. It uses high quality imported carbon molecular sieve (CMS) as adsorbent and adopts pressure swing adsorption (PSA) principle at normal temperature to separate air and produce high purity nitrogen.
Oxygen and nitrogen have different diffusion rates on the surface of the molecular sieve. The gas molecule with smaller diameter (O2) has a faster diffusion rate and more enters the micropores of the carbon molecular sieve, while the gas molecule with larger diameter (N2) has a slower diffusion rate and less enters the micropores of the carbon molecular sieve. This selective adsorption difference between nitrogen and oxygen by carbon molecular sieve results in oxygen enrichment in adsorption phase and nitrogen enrichment in gas phase in a short time, so oxygen and nitrogen separation, and gas phase enrichment nitrogen is obtained under PSA conditions.
The difference curve of adsorption capacity of carbon molecular sieve for oxygen and nitrogen at a certain time under different pressures:
After a period of time, the adsorption of oxygen by the molecular sieve reaches a balance. According to the characteristics of the adsorption amount of adsorbed gas by the carbon molecular sieve under different pressures, the pressure is reduced to remove the adsorption of oxygen by the carbon molecular sieve, which is a process of regeneration. According to the different regeneration pressure, it can be divided into vacuum regeneration and atmospheric regeneration. Atmospheric regeneration is conducive to the thorough regeneration of molecular sieve and easy to obtain high purity gas.
Pressure swing adsorption nitrogen machine (PSA nitrogen machine for short) is a nitrogen generating equipment designed and manufactured according to pressure swing adsorption technology. Two adsorption towers are usually used in parallel, and the automatic control system strictly controls the timing according to a specific programmable program, alternately performs pressure adsorption and decompression regeneration, completes nitrogen and oxygen separation, and obtains the required high purity nitrogen.
The performance of dynamic adsorption capacity and separation coefficient of carbon molecular sieve (CMS) determines the quality of nitrogen making machine.
(Automatic conversion)
Carbon deoxidation
Nitrogen from pressure swing adsorption, (carbon deoxidation) (oxygen and carbon combustion reaction into water gas and carbon monoxide and carbon dioxide, part of the freeze drying condensation, the other part with carbon dioxide and other impurities are removed by the adsorbent in the dryer, dust is removed by the filter).
The deaeration process has low energy consumption, compact mechanism, reliable performance, lower cost than other methods to obtain high purity nitrogen, and no catalyst regeneration. Desiccant has a long adsorption period and can be recycled and used.
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Device feature
PSA nitrogen machine features
◆ Easy installation:
Equipment structure is compact, the whole skid, small footprint without infrastructure investment, less investment;
◆ More economical than other nitrogen supply methods
PSA process is a simple nitrogen production method, using air as raw material, energy consumption is only the electric energy consumed by the air compressor, with low operating cost, low energy consumption, high efficiency.
◆ Electromechanical instrument integration design to achieve automatic operation
Imported PLC control automatic operation. Nitrogen flow pressure purity can be adjusted and continuously displayed, pressure, flow, purity alarm can be set and remote automatic control and detection and measurement can be realized to achieve true unmanned operation. The advanced control system makes the operation easier, thus ensuring the stability of gas purity and flow.
◆ High-quality components are the guarantee of stable and reliable operation
Pneumatic valve, electromagnetic pilot valve and other key components are imported configuration, reliable operation, fast switching speed, service life of more than one million times, low failure rate, easy maintenance, low maintenance costs.
◆ Oxygen content continuous display, automatic alarm system:
Monitor the nitrogen purity online to ensure that the required nitrogen purity is stable.
◆ High-quality carbon molecular sieve:
It has large adsorption capacity, high compressive performance and long service life. Normal operation life of up to 8 ~ 10 years.
◆ Constant flow gas distribution technology
Troy provides excellent equal flow air distribution device, including plate air distribution, two-stage air buffer design, wide air collection device, so that the compressed air can be evenly distributed at the same flow rate when entering the adsorption tower, to ensure that each molecular sieve is exposed to the same pressure, the same flow rate, to ensure that each molecular sieve is working at full load, to maximize the adsorption efficiency of the molecular sieve. Achieve the best nitrogen production results. At the same time, it also saves the air source and reduces the energy consumption. However, the traditional air distribution technology has low utilization rate of molecular sieve near the inner wall of the tower, resulting in low utilization efficiency of molecular sieve and unbalanced life of molecular sieve. Effectively prolong the service life of carbon molecular sieve.
◆ Pressure difference indicator, centralized discharge:
Each stage of the filter has a differential pressure indicator and a centralized automatic blowdown system.
◆ Ideal purity selection range:
The purity of nitrogen is easy to adjust, and can be adjusted between 95% and 99.9% according to the needs of users. Coupled with the unique purification technology, the series of nitrogen purifiers in the post-stage can produce 99.9995% high-purity nitrogen.
◆ Unique cycle switching process:
The valve wear is reduced, the service life of the equipment is extended and the maintenance cost is reduced.
◆ Free debugging, lifelong maintenance:
Strong technical strength and quality after-sales service, to provide continuous technical support, users use no worries.
Nitrogen purification characteristics
◇ Carbon deoxidation
When the amount of nitrogen fluctuates, the parameters of high purity gas are stabilized according to the nitrogen flow rate. Oxygen and carbon combustion reaction into water gas and carbon monoxide and carbon dioxide, part of the freeze drying condensation, the other part with carbon dioxide and other impurities are removed by the adsorbent in the dryer part, (note: carbon monoxide and carbon dioxide in the general workpiece process, no impact, only the food packaging industry can not be used) dust removal by the filter.
◇ Multi-stage drying process:
By cooling, freeze drying to remove a lot of water, reduce the adsorption load of molecular sieve, effectively extend the life of molecular sieve.
◇ A variety of switching modes:
Set a variety of manual and automatic switching modes to meet different gas use occasions.
◇ Preheating deaeration system:
The deaerator is equipped with a preheating system to ensure that the equipment can be started at cold temperatures in winter.
◇ Molecular sieve, PLC controller, valve:
All key components are imported with high quality and advanced parts to ensure long-term continuous operation without trouble.
◇ Deoxidation catalyst: 2 kinds (1. Palladium deoxidizer). (2. Carbon deoxidizer)
High efficiency Large adsorption capacity, low operating cost of equipment. Especially suitable for the purity of 99% ~ 99.9% raw material nitrogen deoxygenation purification to 99.9995% or more. The purity of output nitrogen can always be maintained at 99.999% or more, which is not affected by the fluctuation of nitrogen consumption. The heat exchange system can ensure that the deaerator always works in a stable and energy-saving state.
◇ Safe and reliable system:
With a number of interlock control functions, users find and solve problems in time to protect the quality of product gas.
☆ Simple installation:
Skid-mounted structure, small size, compact structure, no need for infrastructure, connected water, electricity and inlet and outlet pipes can be put into normal production.
Chapter four illustrates the system flow path
The protective gas station system is composed of compressed air device, compressed air purification device, pressure swing adsorption nitrogen production device, (carbon deoxidation) nitrogen purification device, and other equipment.
First, compressed air system
The compressed air system consists of a screw compressor and an air buffer tank to provide the air source required for the pressure swing adsorption nitrogen production plant. The system provides a stable output pressure and sufficient air volume. The air compressor is a screw air compressor with reliable operation, simple maintenance, low noise and no foundation operation. The air buffer tank is mainly used as a buffer for the air source, which plays a stabilizing and storage role, and can also collect and remove most of the oil and water condensate entering the compressed air source. Buffer tank with pressure gauge, safety valve, sewage outlet.
The exhaust capacity of the air compressor is slightly greater than the air consumption under the rated output of the nitrogen generator. Because its start and stop are controlled by the exhaust pressure, when the exhaust volume is greater than the consumption volume, the discharge pressure rises and the air compressor is unloaded. On the contrary, the air compressor is loaded. Through such a cycle of start and stop, the air compressor exhaust volume is suitable for the air consumption requirements of the nitrogen machine, and to meet the operation needs of the production line in changing conditions (lower than the rated output).
Second, air purification system
The compressed air from the buffer tank first enters the C-level filter to achieve coarse filtration, and then enters the refrigerated dryer to force the compressed air to cool down, so that the water vapor in the air condenses, and the condensed liquid water carries dust and oil out of the machine. The cold dryer is best placed in the compression room. The process uses a freeze dryer to remove oil water, based on three reasons:
1, the maximum liquid load at the intake port of the T-level gas supply pipeline filter: 2000ppm w/w dew point < -12℃, do not use freeze dryer, T-level gas supply pipeline filter easy to fail;
2, winter outdoor temperature is low, compressed air temperature is reduced after the precipitation of water, blocking the pipeline system, the pipeline system needs to tilt and drain liquid;
3, the pipeline system is easy to corrosion and rust after precipitation of water.
The post-precision filter group of the cold dryer is composed of a two-stage filter. They are the T-class main flow filter and the A-class efficient oil mist removal filter. The T-class main flow filter has a precision of 1um, filters 1um and larger solid and liquid particles, and the residual oil content is 1ppm w/w. A high efficiency oil mist filter filtration accuracy 0.01um filter 0.01um and larger solid and liquid particles, 99.999+% oil mist; Residual oil content 0.001ppm w/w. The compressed air quality reaches ISO8573.1 quality grade 1.
4, activated carbon adsorption filter
In order to avoid the trace oil after T filtration into the carbon molecular sieve of pressure swing adsorption, an activated carbon adsorption filter is added to ensure that the air entering the nitrogen machine is cleaner.
Third, pressure swing adsorption nitrogen production system
The PSA carbon molecular sieve nitrogen production unit has two adsorption towers filled with carbon molecular sieve. Clean and dry compressed air enters the pressure swing adsorption nitrogen production unit and flows through the adsorption tower filled with carbon molecular sieve. Compressed air flows through the adsorption tower from bottom to top, and the adsorption force of nitrogen and oxygen under different pressures is different with molecular sieve. Oxygen, water, carbon dioxide and other components are adsorbed on the surface of carbon molecular sieve, and the unadsorbed nitrogen is collected as product gas at the outlet, which flows out from the upper end of the adsorption tower and enters the buffer tank. After a period of time, the oxygen adsorbed by carbon molecular sieve in the adsorption tower reaches saturation and needs to be regenerated.
Regeneration is achieved by stopping the adsorption step and reducing the pressure of the adsorption tower. After a short period of pressure equalization, the adsorption tower begins to reduce pressure, and the adsorbed oxygen, water, carbon dioxide and other components are removed to complete the regeneration process.
The two adsorption towers are alternately adsorbed and regenerated to produce product nitrogen with stable flow and purity. The switch between the two adsorbers is automatically completed by a programmable valve controlled by PLC. The performance of a pressure swing adsorption nitrogen production device depends on the performance of the adsorber, carbon molecular sieve, process flow, equipment structure and electromagnetic pneumatic valve. The pressure swing adsorption nitrogen production device of our company adopts PLC programmable controller produced by Mitsubishi Corporation of Japan, imported carbon molecular sieve and electromagnetic pneumatic valve produced by Baode company of Germany.
4. Nitrogen purification system (carbon deoxygenation)
In terms of nitrogen purification, our company has a variety of programs for customers to choose. Now according to your company's nitrogen index requirements, our company can meet your requirements through the following programs.
The ordinary nitrogen from the PSA nitrogen production unit, through the deaerator filled with carbon deoxidizer, the micro-oxygen in the crude nitrogen and excess carbon and oxygen combustion reaction at 300-350℃ temperature to produce water. After the deaeration of nitrogen through the water cooler and then into the freeze dryer condensation deliquid into the adsorption dryer, dryer is equipped with molecular sieve, water and carbon dioxide and other impurities are removed by the adsorbent in the dryer, dust is removed by the filter. The water in nitrogen is deeply adsorbed, the dew point can reach -60℃ -65℃ or more, and the residual oxygen in nitrogen can be less than 3ppm.
The nitrogen purification unit has two dry adsorption towers filled with molecular sieve, one is adsorbed while the other is regenerated. The cycle process of periodic adsorption and regeneration ensures the stable and continuous operation of the system.