Piston, screw, and centrifugal compressors each have their own applicable scenarios for compressing industrial nitrogen gas, as follows:
Piston compressor
Applicable scenarios: Suitable for industrial nitrogen compression applications with small to medium flow rates and high pressure requirements, such as small chemical enterprises, laboratories, food packaging, and other fields. It performs well in applications that require high nitrogen pressure and compression to tens of megapascals or even higher, such as nitrogen pressurized storage and high-pressure reactions in certain chemical processes.
Advantages: High output pressure, maximum pressure can reach 560MPa; Widely applicable, the working medium can be hydraulic oil, water, and most chemically corrosive liquids, with high reliability and long maintenance free life; Flexible application, different models of pumps can be selected to obtain different pressure zones; Easy to adjust, the output hydraulic pressure can be infinitely adjusted within the pressure range of the pump; Can automatically maintain pressure and keep the circuit pressure constant; Safe operation, using gas drive, no arc or spark, can be used in hazardous areas; Easy maintenance, few parts and seals.
Limitations: The gas carries oil stains, and if high quality requirements are placed on nitrogen, the purification task of compressed gas is heavy; The speed is limited, and for situations with large displacement, the external dimensions and foundation are relatively large; Discontinuous exhaust and fluctuating gas pressure may cause damage to the pipeline network or components; There are many vulnerable parts and a large amount of maintenance.
Screw compressor
Applicable scenarios: Suitable for industrial nitrogen compression in medium flow and pressure ranges, widely used in industries such as chemical, electronics, and pharmaceuticals. It has advantages in situations where continuous and stable supply of nitrogen at a certain pressure is required, such as gas transportation in chemical production and nitrogen protection in electronic chip manufacturing.
Advantages: Continuous compression process, stable gas flow rate, and stable exhaust pressure; Simple structure, few vulnerable parts, high reliability, and low maintenance costs; Capable of working under large pressure differentials or pressure ratios, with low exhaust temperatures; Has a certain tolerance to small amounts of impurities and moisture contained in the gas; It has good gas transmission regulation and can flexibly adjust the nitrogen supply according to actual needs.
Limitations: Compared to piston compressors, it is slightly lacking in high pressure output; Oil injected screw compressors require components such as oil and gas separators and oil filters, which can cause pressure drop and require regular replacement of spare parts; The one-time investment cost of oil-free screw compressors is relatively high.
Centrifugal compressor
Applicable scenarios: Suitable for industrial nitrogen compression with high flow rate and low to medium pressure, commonly used in large chemical enterprises, refineries, air separation units and other occasions with huge demand for nitrogen.
Advantages: High flow rate, capable of meeting large-scale nitrogen compression needs; Simple structure, reliable operation, easy maintenance, and long service life; High speed, able to achieve continuous and stable compression process, with small gas pressure pulsation; High efficiency, especially under high flow conditions, with relatively low energy consumption; Flexible adjustment of air volume and pressure can be achieved by adjusting the impeller speed and other methods.
Limitations: High requirements for gas cleanliness, impurities and particles contained in the gas may damage components such as impellers; Under low flow and high pressure conditions, the efficiency is low and not suitable for nitrogen compression needs with low flow and high pressure; The equipment investment cost is high, and the installation and foundation requirements are complex.
The economic comparison of piston, screw, and centrifugal compressors is as follows:
Procurement cost
Piston compressor: The structure is relatively simple, the materials are ordinary, the processing difficulty is small, and the price of small piston compressors is low. The price of large or high-pressure piston compressors may increase, but they are usually still lower than centrifugal compressors of the same specifications, generally ranging from tens of thousands to hundreds of thousands of yuan.
Screw compressor: The precision requirements for components are high, the processing equipment is expensive, and the overall price is higher than that of piston compressors. The price of screw compressors with small and medium flow rates and low to medium pressure ranges from tens of thousands to hundreds of thousands of yuan, while the price of screw compressors with large flow rates and high pressure may be higher.
Centrifugal compressors: with complex structures, high manufacturing technology requirements, and strict material performance requirements, especially for large, high-pressure, and high flow centrifugal compressors, the procurement cost is high, usually ranging from tens of thousands to millions of yuan, or even higher.
running cost
Piston compressor: When the speed is low and the displacement is constant, the power consumption is relatively high, and as the service life increases, the performance decreases and the energy consumption increases. It requires regular replacement of vulnerable parts such as piston rings and valve plates, resulting in high maintenance costs. For example, the annual maintenance cost of a small piston compressor may be several thousand yuan.
Screw compressor: With high operating efficiency, it consumes less energy than piston compressors under the same displacement and pressure. For example, taking the 20m ³/min and 0.75MPA models as examples, screw compressors can save 16800 yuan in electricity costs per year compared to piston compressors. It has few vulnerable parts, low maintenance workload, stable operation, and low maintenance costs. Generally, the annual maintenance cost ranges from several thousand yuan to tens of thousands of yuan.
Centrifugal compressor: High efficiency and low energy consumption under high flow conditions, but efficiency decreases and energy consumption increases under low flow conditions. Its operation is reliable, with few vulnerable parts and relatively low maintenance costs. However, once a malfunction occurs, the maintenance technology is difficult and the cost is high.
service life
Piston compressor: There are many vulnerable parts, and frequent maintenance can affect overall performance and service life. The general service life is 10-15 years.
Screw compressor: simple structure, few vulnerable parts, stable operation, and a service life of generally 15-20 years.
Centrifugal compressor: The mechanical structure is relatively simple, the operational reliability is high, and the service life is long, generally up to 20 years or more.
Overall, piston compressors have low procurement costs but high operating and maintenance costs, making them suitable for scenarios with low gas volume requirements, high pressure requirements, and low frequency of use; Screw compressors have a relatively balanced cost in procurement, operation, and maintenance, and are suitable for scenarios with medium flow and pressure ranges and high requirements for gas supply stability; Centrifugal compressors have high procurement costs, but low operating costs at high flow rates, making them suitable for large-scale production scenarios with high flow rates and low to medium pressures.
