Common air compressor selection reference
Faced with a variety of compressors with different functions on the market, many users are unable to have a precise understanding of compressor selection. , sometimes it is because the efficacy and performance of different compressors are not fully understood, resulting in the inability to choose a reliable, efficient, and energy-saving compressor model reasonably.
According to the user's specific situation and actual process requirements, select an air compressor suitable for production needs. It is not advisable to blindly choose high-quality and high-priced models to save money, nor to blindly choose low-quality models with frequent failures to save money. After all, air compressors are important power equipment in industrial production. .
Now we will give a brief introduction to the advantages and disadvantages of several commonly used compressor types and their scope of application, hoping to serve as a reference for users when choosing a compressor.
According to the different gas modes of the compressor, compressors are usually divided into two categories, namely volumetric and dynamic (also known as speed) compressors. Due to their different structural forms, positive displacement and power compressors are classified as follows:
Screw compressor
Screw air compressor is a type of rotary positive displacement compressor , in which two rotors with helical gears mesh with each other to compress and discharge the gas.
Screw air compressors are divided into single screw and twin screws according to the number; according to whether lubricating oil is involved in the compression process, they are divided into oil-injected and oil-free screw air compressors, and oil-free compressors are further divided into There are two types: dry type and water spray type.
Screw air compressors generally have a simple structure, few wearing parts, low exhaust temperature, and large pressure ratios. They are especially not afraid of liquid and dust-laden compression in the gas. The advantages of oil-injected screw compressors The emergence of screw compressors for power technology and refrigeration (including screw air compressors, screw refrigerators, etc.) has developed rapidly at home and abroad.
Working Principle
The screw air compressor uses the mutual meshing of the male and female screw rotors to continuously reduce the volume between the teeth and increase the gas pressure, thereby continuously generating compressed air. Screw air compressors are also positive displacement compressors, but due to the working principle of the screw type, compared with piston air compressors, screw air compressors have stable air supply and generally do not need to be equipped with a gas storage tank. The working process is shown in the figure below.
Main advantages
1. High reliability: The screw air compressor has fewer parts and less wearing parts, so it operates reliably and has a long life.
2. Easy operation and maintenance: operators do not need to undergo long-term professional training and can achieve unattended operation. The operation is relatively simple and the air can be supplied according to the required exhaust volume.
3. Good power balance: the screw air compressor has no unbalanced inertial force, the machine can work smoothly and at high speed, and can achieve foundation-free operation. It is especially suitable for use as a mobile compressor, with small size and low weight. Light and takes up less space.
4. Strong adaptability: The screw air compressor has the characteristics of forced air transmission, the exhaust volume is almost not affected by the exhaust pressure, the operation is stable, the vibration is small, the exhaust is stable, and it can be used in a wide range Internal energy maintains high efficiency.
5. Multi-phase mixed transport: There is actually a gap between the rotor tooth surfaces of the screw air compressor, so it can withstand liquid impact and can pressurize liquid-containing gases, dust-containing gases, and easily polymerizable gases.
6. The unit exhaust volume is small, saving floor space.
Although screw compressors have the above advantages, in order to keep the screw compressor unit operating normally, safely and reliably, and with a long working life, a detailed maintenance plan must be formulated. It is best to perform scheduled operations, regular maintenance, and regular inspection and maintenance to keep the compressor clean, oil-free, and dirt-free. Only by comprehensively mastering maintenance knowledge and being familiar with troubleshooting methods can the smooth operation of the compressor be ensured.
Main Disadvantages
1. Because it has strong balance and can operate at high speed, the power consumption is relatively high.
2. After long-term operation, the screw clearance will become larger, and the cost of regular repair or replacement will be high.
Scope of application
Screw compressors have unique advantages such as high reliability, easy maintenance, and strong adaptability. With the continuous deepening of research and the continuous improvement of design technology, The performance of screw compressors will be further improved, and its application fields will become more and more extensive.
In addition to traditional applications, the application of screw compressors in new fields such as fuel and batteries will expand rapidly. At the same time, due to the continuous improvement of the working reliability of screw compressors, they have gradually replaced reciprocating compressors in the medium cooling capacity range and occupied part of the centrifugal compressor market.
Development Trends
In the petrochemical field, domestic centrifugal compressors currently cannot meet domestic needs in terms of high technology and special products. In addition, there is still a gap with foreign countries in terms of technical level, quality, and completeness. As the scale of my country's petrochemical production continues to expand, centrifugal compressors will face new issues in terms of large-scale production. There is still no mature experience in the design and manufacture of these large-scale gas compressors in China. Due to the challenge from single-screw compressors, part of the twin-screw air compressor market will be squeezed out by single-screw compressors. However, domestic twin-screw process compressors have always relied on imports, so twin-screw process compressors will be a development direction.
Centrifugal Compressor
A centrifugal compressor is a powered compressor in which one or more rotating impellers (blades usually on the sides) accelerate the gas, and the main air flow is radial. Power compressors are divided into jet and turbine compressors, and centrifugal compressors belong to turbine compressor units. In a centrifugal compressor, the high-speed rotating impeller gives the gas a centrifugal force and a diffusion channel to the gas, thereby increasing the gas pressure.
Working Principle
The centrifugal air compressor uses an impeller to drive the gas to rotate at high speed, causing the gas to generate centrifugal force. Due to the expansion flow of the gas in the impeller, the gas passes through the impeller. The final flow rate and pressure are increased to continuously produce compressed air. Centrifugal air compressors are speed compressors. When the air load is stable, centrifugal air compressors work stably and reliably.
Main advantages
1. Large flow, high power, and energy saving. The medium flowing through the impeller of a turbomachinery is always continuous. The volume of the cylinder is large and the impeller can rotate at high speed, so the exhaust flow rate and power generated by the turbomachinery can be greatly increased. Therefore, the exhaust of the centrifugal compressor is even and the air flow is pulse-free.
2. The structure is compact, the sealing effect is good, the leakage is less, and the size is small. Therefore, the unit occupies a much smaller area and weight than a piston compressor with the same air volume.
3. It runs smoothly and operates reliably, so it has a high operating rate, a flat performance curve, a wide operating range, and less maintenance costs and personnel.
4. The compression process of the centrifugal compressor can be absolutely oil-free, and no lubrication is required inside the machine, which is very important for the production of many industries.
5. There are few wearing parts, a long operating cycle, few and simple moving parts, and low manufacturing precision, so its manufacturing cost is relatively low and its reliability is high. Easy to automate and scale up.
Main Disadvantages
1. Centrifugal compressors are currently not suitable for situations where the gas volume is too small and the pressure ratio is too high.
2. The stable operating range of the centrifugal compressor is narrow. Although its gas volume adjustment is more convenient, it is less economical. The air flow velocity is high, and the components in the flow channel have large friction losses.
3. The efficiency of centrifugal compressors is generally still lower than that of piston compressors. The operating adaptability is poor, and the properties of the gas have a greater impact on the operating performance. When the unit starts, stops, and operates, the load changes greatly.
4. The centrifugal compressor has a high speed and may produce mechanical vibration. In terms of operating characteristics, there will be surge phenomenon, which is extremely harmful to the machine.
5. The operation is relatively complicated, the gearbox is noisy, the equipment has high technical content, and the maintenance cost is high.
Scope of application
In recent years, the chemical industry and large-scale chemical plants have been established one after another, making centrifugal compressors a key machine for compressing and transporting various gases in chemical production. occupy an important position. With the achievements in gas dynamics research, the efficiency of centrifugal compressors has been continuously improved, and due to the successful development of key technologies such as high-pressure sealing, processing of small-flow narrow impellers, and multi-oil wedge bearings, the problem of centrifugal compressors moving towards high pressure and wide range has been solved. A series of problems related to the development of flow range have greatly expanded the application range of centrifugal compressors, so that they can replace reciprocating compressors in many situations, greatly expanding the application range.
Some basic chemical raw materials, such as propylene, ethylene, butadiene, benzene, etc., can be processed into important chemical products such as plastics, fibers, and rubber.
In petrochemical plants that produce this basic raw material, centrifugal compressors also play an important role and are one of the key pieces of equipment. In addition, centrifugal compressors are also extremely critical equipment in other industries such as petroleum refining and refrigeration.
Development Trend
At present, centrifugal compressors can be used to compress and transport various gases in chemical production, and their exhaust pressure has been greatly improved compared with the early days. The minimum air volume has also been reduced, which correspondingly expands the application range of centrifugal compressors.
Centrifugal compressors need to develop towards large capacity to meet the requirements of the ever-expanding scale of petrochemical production in my country. At the same time, with the development of new technologies, the emergence of new gas seals, magnetic bearings and non-lubricated couplings , the development trends of centrifugal compressors are mainly as follows: continuous development of high-pressure and small-flow products; further research on ternary flow theory and application of it to the design of impellers, blade diffusers and other components, in order to achieve high-efficiency units; low-noise , adopt noise protection to improve the operating environment. Especially with the development of chemical and petrochemical production, the scale of production continues to increase. With its superior performance, centrifugal compressors are increasingly used in many industrial fields and have a good development trend.
Piston compressor
Piston compressor is the most common positive displacement compressor. It uses a crank connecting rod mechanism to change the rotational motion of the driver into the reciprocating motion of the piston. The piston and the cylinder together form the working chamber of the compressor. Relying on the reciprocating motion of the piston in the cylinder and the automatic opening and closing of the inlet and exhaust valves, the gas periodically enters the cylinder working chamber for compression and discharge.
A piston compressor is mainly composed of three parts; the moving mechanism (crankshaft, bearings, connecting rods, crosshead, pulley or coupling, etc.), and the working mechanism (cylinder, piston, valve, etc.) with the fuselage. In addition, there are three auxiliary systems: lubrication system, cooling system and adjustment system.
The kinematic mechanism is a crank-link mechanism that converts the rotational motion of the crankshaft into the reciprocating motion of the crosshead. The fuselage is used to support and install the entire movement mechanism and working mechanism. The working mechanism is the main component that realizes the working principle of the compressor.
Working principle
In pneumatic transmission, a volumetric piston air compressor is usually used. Piston air compressors use the crankshaft to drive the reciprocating motion of the piston to compress the gas in the cylinder cavity and continuously generate compressed air. Piston air compressors are positive displacement compressors. Due to the working principle and characteristics of this model, in order to stabilize the air supply, generally piston air compressors are equipped with air storage tanks.
Main advantages
1. Wide applicable pressure range. Because it works on the principle of volume change, it can achieve high working pressure regardless of its flow rate. At present, various low, medium, high and ultra-high pressure compressors have been made, among which the working pressure of industrial ultra-high pressure compressors can reach 350MPa (3500kgf/cm2).
2. The equipment has low price, low initial investment, easy operation and long service life.
3. Because the compression process is a closed process, the thermal efficiency is high.
4. Strong adaptability, wide range of exhaust volume, and less affected by changes in exhaust pressure. When the medium changes severely, the changes in volumetric displacement and exhaust pressure are also small.
Main Disadvantages
1. The inertial force is large and the rotation speed cannot be too high, so the machine is bulky, especially when the displacement is large.
2. The structure is complex, there are many wearing parts, the maintenance workload is large, and the maintenance cost is relatively high.
3. The exhaust is discontinuous, the air flow pressure pulsates, and it is easy to produce air column vibration.
4. The vibration and noise are large during operation, and the equipment installation foundation requires high requirements.
Since the piston machine can only intermittently intake and exhaust air, and the cylinder volume is small, the reciprocating speed of the piston cannot be too fast, so the exhaust volume and power of the piston machine are greatly affected. restrictions.
Scope of application
The piston compressor is a reciprocating compressor with pressure levels of medium pressure, high pressure and ultra-high pressure. It is suitable for occasions with higher pressure and medium flow rate. , Small flow range is mainly suitable for medium and small displacement and high pressure occasions.
Development Trends
Piston compressors are the most widely used compressors in traditional fields. However, with the rise of other rotary compressors and other products, they are used in many fields, such as refrigeration. The market is gradually shrinking.
The key ethylene construction projects in the domestic petrochemical field and the vigorous rectification in the coal field in recent years will drive the development of piston compressor technology and its industry. Piston compressors are mainly developing in the direction of large capacity, high pressure, low noise, high efficiency, and high reliability; new types of air valves that operate under changing working conditions are constantly developed to improve the service life of the air valves; in product design, application Thermodynamics and kinetic theories are used to predict the performance of the compressor under actual working conditions through comprehensive simulation; the mechanical and electrical integration of the compressor is strengthened, and computational automatic control is adopted to achieve optimized energy-saving operation and online operation.
In order to carry forward the advantages and overcome the shortcomings, the structural parameters tend to be high speed and short stroke to make the structure compact. At the same time, the life of wearing parts such as valves and sealing components is extended to improve the operating rate. With the development of optimal design theory and computer technology, new prospects have been created for rationally selecting design parameters and improving efficiency.
Sliding vane compressor
Sliding vane compressor is a type of rotary compressor. Its axial sliding vanes move radially on the eccentric rotor of the same cylindrical cylinder. Sliding, the air trapped between the sliding plates is compressed and discharged. There are two situations in rotary compressors: one is that the sliding vanes are installed in the slots on the cylinder. Since the sliding vanes do not rotate with the rotor, it is called a fixed sliding (blade) vane compressor, that is, a rolling piston compressor; The other is that the sliding vane is installed in the slot of the rotor and rotates with the rotor. It is called a rotating sliding (blade) vane compressor, referred to as a sliding vane or rotary vane or rotary vane compressor.
Working Principle
The sliding vane compressor is mainly composed of three parts: the body (i.e. cylinder), the rotor and the sliding vane. The outer surface of the rotor and the inner surface of the cylinder are circular, and the rotor is installed eccentrically in the cylinder so that they are tangential, forming a crescent-shaped space between the inner wall of the cylinder and the outer surface of the rotor. There are a number of slide slots on the rotor, and each slot is equipped with a freely sliding slide. When the rotor rotates, the slide is thrown out of the slot by centrifugal force, and its end is close to the inner surface of the cylinder, pushing the crescent. The shaped space is divided into several fan-shaped chambers, which are called primitives. With the continuous rotation of the rotor, the volume of the element changes from small to large.
Main advantages
1. Simple structure, few parts, easy processing and assembly, and convenient maintenance.
2. Smooth operation, low noise, small vibration and small starting impact.
3. Compact structure, small size and light weight, easy to install in narrow spaces.
4. The gas transmission volume is large, the flow is uniform, and the pulsation is small, so there is no need to install a large gas reservoir.
Main Disadvantages
1. The mechanical friction between the sliding vane, the rotor and the cylinder is serious, resulting in large wear and energy loss.
2. Due to greater wear and tear, the service life and efficiency are lower.
Scope of application
Sliding vane compressors are mainly used as air compressors. The displacement is generally 0.3~40m3/min, and the market share is low. According to the different lubrication methods, it can be divided into three categories: oil dripping, oil spraying and oil-free. Sliding vane compressors are widely used in various compressed air devices, small refrigeration and air conditioning devices and automobile air conditioning systems. In the chemical and food industries, oil-free machines can be used to convey or pressurize various gases, and can also be used as a gas source for conveying solid particulate materials. The sliding vane machine can also be used as a vacuum pump.
Development Trend
The rotary vane compressor is a modified structure of the sliding vane compressor. Due to its good starting performance and small change in torque during the compression process, Currently it is mainly used in the air conditioning systems of mini cars and some tool trucks with smaller displacements. The dynamic characteristics at high speed are the main technical research direction of this compressor.
Scroll compressor
Scroll compressors have developed rapidly in the past decade and constitute a new highlight in the development of compressor technology. Vortex type positive displacement rotary compressor has attracted more and more attention due to its small size, high efficiency and smooth operation, and has great application prospects in small compressors. The emergence of high-precision CNC milling machines has also brought development opportunities to the development of scroll machinery.
Working Principle
Scroll compressor is composed of fixed scroll and movable scroll, cross slip ring, main shaft, frame and other main accessories. The fixed scroll and movable scroll are The vortex body or vortex ring is generally composed of uniform and identical involute lines, which are installed opposite each other and have a phase offset of 180°.
When the scroll compressor is working, the movable scroll makes a planar circular motion (around the center of the main shaft) under the drive of the main shaft and the phase maintenance of the anti-rotation mechanism. As shown below.
A pair of working chambers completes a suction-compression-exhaust process. Different numbers of vortex turns have different rotation angles during the compression process. The more vortex turns, the larger the rotation angle. When the outermost suction chamber forms a closed volume and begins to push toward the center, another new suction chamber begins to form at the same time, and the above process is repeated. Therefore, regardless of the number of scrolls, the compressor completes a suction and exhaust process every revolution.
Main advantages
1. Simple mechanism, small size and light weight.
2. Few wearing parts and high volumetric efficiency.
3. The friction of the machine is relatively small, so the mechanical efficiency is high.
4. Multiple working chambers work at the same time, with uniform torque.
Main Disadvantages
1. Like most rotary machinery, scroll machinery has high precision requirements for parts, so the cost of parts processing is high.
2. The variable working condition performance is poor, and the working chamber cannot be cooled externally, so it is difficult to export heat.
3. Due to the limitations of the working chamber seal and the strength conditions of the parts, the exhaust pressure is low.
Application Scope
The field of air conditioning compressors is the most suitable field for scroll machinery to be used in compressors, and it is also the field with the largest product output at present; due to the pressure comparison of scroll compressors It is large, so it is also suitable for refrigeration compressors; the compression process index of scroll compressors is large, and it is also used for air compression and other gas compression; scroll machinery can also be used as a vacuum pump.
Development Trend
Scroll compressors currently have an absolute advantage in the field of cabinet air conditioners. It has shown strong competitiveness in the field of vehicle air conditioning. Its development lies in expanding its cooling capacity range, further improving efficiency, using alternative working fluids and reducing manufacturing costs.
Conclusion
With the development of my country's economy, my country's compressor design and manufacturing technology will also develop by leaps and bounds, and the technical level in some aspects has also reached the international advanced level. However, there is still a certain gap between it and the international advanced level in some aspects.
We hope that compressor users can be realistic in their selection and choose economical, reliable, efficient and environmentally friendly compressors based on the needs of the company, so as to avoid problems such as machine maintenance and increased costs caused by incorrect selection. of.
How to select?
1). Selection is based on “need-based selection”
Combined with customer needs, find the best operating economy and expand in the future. Both scales require a lot of decision-making. The basis for decision-making is the purpose or usage process of compressed air. The focus is on calculating air demand, reserve capacity and room for future expansion. Pressure is a decisive factor and has a great impact on energy consumption. Different pressure ranges use different compressors. Opportunities can sometimes be economical.
2) Calculation of working pressure
The compressed air equipment determines the necessary working pressure, which depends on the compressor, equipment, and pipelines. The highest working pressure determines the necessary device pressure. , and pressure reducing valves are used in air-consuming locations to meet equipment needs. In extreme cases, it is uneconomical to equip a separate air compressor.
Working pressure: end user + final stage filtration + piping system + dust filter + dryer + compressor adjustment range
The higher the pressure, the greater the power consumption, which must be considered The pressure drop caused by the size and length of the piping. List the operating pressures of various models. If the operating pressures differ too much, you must purchase air compressors with different pressures. Do not lower the pressure to increase costs.
3) Calculation of air demand
Compressed air is a clean power that converts electrical energy into air potential energy and uses the expansion of compressed air to do work. However, it has a negative impact on electrical energy. The consumption is also very large. Generally speaking, the power consumption required to compress 1m3 of air to 0.7MPa is about 7kW. According to statistics, the power consumption of air compressor stations accounts for about 20% of the total power consumption of the entire enterprise.
This means that saving compressed air and rationally utilizing compressed air will bring you new profit margins!
Air demand: Combine all tools + machinery and equipment + related process air consumption + leakage + wear + future air consumption + usage coefficient (using the standard value of 20%)
4) , Determination of the number and specifications of compressors
According to the required flexibility + control system + energy efficiency
(1) Whether to choose one large machine or multiple small machines ?
The cost of downtime events during production, power utilization, load (load) changes, cost of compressed air system, and available floor space. Due to cost reasons, only one compressor is used to supply all the air in a device, so this system can prepare a quick interface for a mobile compressor for connection when in use, and an old air compressor can be used as an inexpensive The backup power provides reserve air source.
(2) Stability (always a very important issue);
(3) Energy consumption expenditure
①Pipeline leakage; ②Gas demand per day Constant fluctuations every moment (this is the most easily overlooked and the most serious)
③The output efficiency of a single machine (choose the model with the best range of output efficiency)
( 4) Universalization of spare parts
The optimized combination of multiple 110KW models may be 40-160m3/min, which is the best choice for the gas consumption range.
(5) Operation analysis
Should be observed within a week and measure that the energy recovery is more than 90%. The working pressure often drops during a certain period of time. The control system can be modified according to changes in production to improve the use of the air compressor. Another factor is to check whether there is air leakage.
Pay attention to the energy consumption ratio in order to save electricity: actual displacement/actual motor power consumption. The larger the value, the greater the power consumption.
2. Selection of refrigerated dryer
In order to remove moisture from the air, your company uses an adsorption dryer. It can be seen that the air quality requirements of air equipment and tools are Very high.
When selecting a refrigerated dryer, you usually only need to select a dryer with a processing capacity equal to or slightly greater than the air compressor flow rate based on the air compressor flow rate.
For enterprises that have higher requirements for moisture in the air of refrigerated dryers but do not need to use an adsorption dryer, they can increase the size of the refrigerated dryer by one level or choose two dryers. machines in parallel.
3. Selection of adsorption dryer
1) Heatless regeneration (PSA)
After being used for a period of time, the desiccant will tend to saturated, and it must be dried and regenerated. The simplest and most commonly used method is to draw out part of the dried air from the outlet of another tank, and then blow dry the moist desiccant after decompression and expansion. For heatless regeneration type For a dryer, approximately 14% of the rated flow rate of air is required to completely regenerate it.
It is suitable for the use of compressed air in the regeneration process of small air flow. The air consumption requires 15-20% of compressed air at a working pressure of 7 bar, and the pressure dew point is -40°C. The lower the pressure dew point of the dryer, the greater the air consumption required.
2) Heating regeneration (TSA)
In addition, if some heating devices, such as heating rods, etc., are added to the drying tank, the temperature of the desiccant will be increased to 200°C during regeneration. This can use less regeneration air and save a lot of energy consumption. Only 4% of the regeneration air is needed to achieve complete regeneration, saving about 10% of the compressed air volume. Generally speaking, heating regeneration is usually used in larger units or locations where compressed air flow is restricted. Although the initial investment is high, it can save more costs in the long term.
Heating regeneration is usually used in larger units or when the compressed air flow is large.
1) Micro-heat regeneration
Micro-heat regeneration adsorption dryer is a compressed air adsorption dryer with Chinese characteristics. The original design intention is to reconcile heatless and heated drying. The characteristics of the dryer are used to produce a dryer that consumes less regeneration air than the heatless type and consumes less heating power than the heated type.
In terms of structure, the micro-heating type uses the dry air generated by itself for desorption, and uses an external heating source to micro-heat the desorption air. The purpose of this is said to be to save regeneration gas consumption.
However, theoretical research shows that the actual situation is not so ideal; after a small amount of regas heated to a certain temperature enters the regeneration tower, its temperature is immediately absorbed by a large amount of adsorbent. In other words, to make the regeneration exhaust temperature reach the required value, first To make the adsorbent in the tower reach this temperature, a large amount of regeneration gas will be consumed.
The microthermal regeneration type uses its own dry air to depressurize the adsorbent. Since the water pressure is low, it is the same as the heatless regeneration type, even if it is not heated, it has the ability to adsorb the adsorbent. The ability of the agent to desorb. By heating, the gas carries more water vapor at the outlet, thereby saving the amount of regeneration gas. The higher the temperature of the regeneration exhaust gas, the less the regeneration gas consumption is - this is the micro-thermal design idea.
Like the thermal type, the microthermal type not only has the problem of desorption temperature, but also the problem of the heat required for the desorption process. Because when the additional gas is heated, the metal cylinder and the adsorbent are heated together, and the heat required for these additional heatings greatly exceeds the heat required for the desorption gas itself. If the heat required in the desorption stage is determined by the power of the external electric heating equipment after calculation, then the heat entering the regeneration tower must be carried by the desorption gas. That is to say, the compressed air taken from the dryer itself is not only used to desorb the adsorbent, but also takes on the additional task of heating the adsorbent and the metal tower. As a result, gas consumption is greatly increased. The above steps are only the first step in the entire regeneration process, and approximately the same amount of gas will be consumed during the adsorbent blowing and cooling stage. Therefore, generally speaking, it is not certain that the micro-heating type can save regeneration gas consumption while achieving the same effect as the heatless type. The microthermal type uses the principle of pressure swing adsorption to desorb the adsorbent. However, since the regeneration gas must be cooled after heating the adsorbent in the later stages of physiology, it is a dryer that works in a long cycle (the half-working cycle is as long as 1 to 4 hours). Its adsorbent filling capacity is smaller than that of the athermal type. Therefore, the adsorbent adsorbs much more water per unit mass than the athermal type, which will have a negative impact on the dew point indicator.
In addition, the disadvantages of the heated type are also reflected in the micro-heated type. In terms of regeneration energy consumption, it cannot be generalized whether the micro-heated type is less than the heated type. It is entirely possible if it is not handled properly. The overall energy consumption is greater. Compared with the heatless type, it is conclusive that the overall energy consumption of the microthermal type is greater to achieve the same processing effect.
Therefore, unless there is a serious shortage of air compressors and the factory is extremely rich in power supply, there is no outstanding reason to choose the micro-heating type.
Conclusion: No matter which one of the above three options is chosen, compressed air is required. When selecting the air compressor, the regeneration air required by the dryer must be taken into consideration.
4. Selection of pipeline filters
Usually, the selection of pipeline filters only needs to be based on the flow rate of the air compressor, and the processing capacity is equal to or slightly larger than that of the air A filter for compressor flow is sufficient.
Pipeline filters have different precisions, and the choice of precision depends on the company's air quality requirements. Currently, the air compressors that are widely used on the market are mainly divided into screw air compressors and piston air compressors. Because the oil content of the compressed air of piston air compressors is 25-150PPM, three-stage filtration is required. For screw air compressors, the oil content of compressed air is usually 2-3PPM, so the filter selection generally goes through two stages. Filtration treatment can meet customers' requirements for air quality. Of course, in special cases, we can also add activated carbon filters to handle it.
5. Selection of gas storage tank
Usually a simple method is 15-30% of the air compressor air output (in m3/min). If you want to calculate it, the following formula can be used.
V = air barrel volume; Q = air compressor air volume (m3/min); 8 = constant (generally used at 7bar);
△P = pressure difference ( bar, usually set at least 0.6-1bar)
In addition, when selecting, the working pressure must be determined according to customer needs, which not only meets customer needs, but also saves investment costs.