【Mechanical Equipment Technology Edition】Daily Question 20171026: Compressor speed issue
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Starting today, in order to enhance communication among those interested in marine equipment, we have launched the 【Question of the Day】 initiative on the Technical Forum for Moving Equipment. We encourage everyone to participate actively so that we can all progress and improve together! ! ! Rewards: 3 wealth points for active participation, 10-15 wealth points for correct answers. This question is valid for two days; no scoring will be given after that period. In industrial refrigeration, the common types of compressors are piston-type, screw-type, and centrifugal-type. Piston-type and screw-type compressors belong to the volume-type compressors ； Centrifugal compressors belong to the velocity-type category. Screw compressors also operate at high speeds; therefore, screw compressors combine the characteristics of both types: they are of the volume-type category while simultaneously having a high speed of around 3000 revolutions per minute. The maximum speed of piston compressors is 1450 revolutions per minute. Why can’t piston compressors achieve higher speeds? ? ? ? ================================ High-quality promotions: Mechanical equipment——Maintenance procedures for York screw compressors http://bbs.hcbbs.com/thread-1806833-1-1.html Mechanical equipment——Upgrading of York Quinton control centers http://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——Major repairs for GEA Grasox screw compressors http://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——Disassembly and maintenance of British HOWDEN screw compressors http://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Disassembly and maintenance of Japanese Maekawa MYCOM screw compressors http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1786445
Because higher rotational speeds often lead to a sharp increase in mechanical friction losses within the machine, resulting in a significant decline in the compressor’s performance and efficiency.
A piston compressor converts the rotational speed of the driving mechanism into linear motion of the piston. When the rotational speed exceeds a certain value, wear increases rapidly; the operating speed of components such as valves cannot keep up, resulting in reduced efficiency or damage to these components.
A piston compressor converts the rotational speed of the driving mechanism into linear motion of the piston. When the rotational speed exceeds a certain value, wear increases rapidly; the operating speed of components such as valves cannot keep up, resulting in reduced efficiency or damage to these components
The rotational speed not only determines the compressor’s size, weight, and production cost, but also affects its power consumption, wear level, and operational reliability. Although increasing the rotational speed allows compressors to have smaller dimensions and reduces costs, it also deteriorates operating conditions; the resulting drawbacks offset some of the benefits gained from increasing the rotational speed, making it potentially counterproductive. Therefore, the rotational speed cannot be considered in isolation; rather, it must be taken into account along with factors such as the production cost of the compressor, its operational reliability, the transmission method, as well as the standardization, versatility, and specifications of the product, in addition to the requirements of the users. As the crankshaft of a piston compressor rotates, the pistons move back and forth via the connecting rods; as a result, the working volume formed by the inner wall of the cylinder, the cylinder head, and the top surface of the piston changes periodically. When the piston of a piston-type compressor begins to move from the cylinder head, the working volume inside the cylinder gradually increases. At this point, gas enters the cylinder through the intake pipe, pushing open the intake valve, until the working volume reaches its maximum value at which point the intake valve closes ； When the piston of a piston-type compressor moves in the opposite direction, the working volume inside the cylinder decreases, causing the gas pressure to rise. When the pressure inside the cylinder reaches and slightly exceeds the exhaust pressure, the exhaust valve opens and the gas is expelled from the cylinder, until the piston reaches its extreme position at which point the exhaust valve closes. When the piston of the piston compressor moves in the opposite direction again, the aforementioned process repeats. In summary, as the crankshaft of a piston compressor rotates one full circle, the piston moves back and forth once, allowing processes of intake, compression, and exhaust to take place sequentially within the cylinder, thus completing one working cycle. If the speed is increased, the mechanical friction losses inside the machine rise sharply, which reduces the compressor’s performance and lowers the work output.
It depends on the linear velocity of the piston; generally, it is 3.5–4.5 m/s. If this value is too high, it will lead to an increase in unbalanced forces and more failures.
It depends on the linear velocity of the piston; generally, it is 3.5–4.5 m/s. If this value is too high, it will lead to an increase in unbalanced forces and more failures.
A piston compressor converts the rotational speed of the driving mechanism into linear motion of the piston. When the rotational speed exceeds a certain value, wear increases rapidly; the operating speed of components such as valves cannot keep up, resulting in reduced efficiency or damage to these components
A piston compressor converts the rotational speed of the driving mechanism into linear motion of the piston. When the rotational speed exceeds a certain value, wear increases rapidly; the operating speed of components such as valves cannot keep up, resulting in reduced efficiency or damage to these components.
In piston compressors, friction losses increase rapidly at high speeds, leading to a decline in efficiency and performance metrics
A piston compressor converts the rotational speed of the driving mechanism into linear motion of the piston. When the rotational speed exceeds a certain value, wear increases rapidly; the operating speed of components such as valves cannot keep up, resulting in reduced efficiency or damage to these components