[Q&A Question 304] 2017.11.18

It addresses the issue of imbalance between driving torque and operating torque, ensuring a uniform compressor speed and reducing the fluctuations in motor current and voltage.

The energy stored during the rotation of the flywheel is used to buffer fluctuations in the rotation angle of the piston reciprocating compressor

Disassembly of the compressor (perform disassembly from top to bottom, from outside to inside, and from components to parts). Before turning the shaft, one should be careful of others to avoid injuring people or damaging the machinery. (1) Removal of safety components and auxiliary equipment: 1. Remove the cover plate on the slide section to access the window. 2. Coordinate with the instrumentation team to remove the instrumentation components of the compressor. 3. Remove the cooling water pipeline from the compressor (ensure the pipeline is protected against freezing in winter). 4. Remove the lubrication oil pipeline of the compressor unit. 5. Remove the coupling guard and check the alignment of the coupling. 6. Remove the coupling bolts and mark them. 7. Check the coupling bolts for any damage such as galling, deformation, or fracture. 8. Check the coupling diaphragm for any damage such as deformation, cracking, or burrs. 9. Remove the nut on the valve cover gland as well as the set screw, then take off the valve cover. When removing the gland, leave two nuts in place symmetrically; use a screwdriver or wrench to pry the gland open slightly first. Only after confirming that there is no pressure inside the cylinder should all the nuts be removed, to prevent the residual pressure in the cylinder from pushing the cover out and causing injury. 10. Use special tools to remove the air valve brake. 11. Use special tools to remove each stage of intake and exhaust valves one by one. (II) Remove the cylinder heads of each stage of the compressor and check and measure the piston top clearance for each stage. 2. Use a crane and the chain hoist attached to it to lift the cylinder head, adjusting the tension of the chain hoist to an appropriate level ； Loosen the cylinder head bolts to separate the cylinder head flange from the cylinder block, then lift the cylinder head and place it gently on the sleeper ； During the removal of the cylinder head, at least two bolts should be left in a diagonal pattern to be loosened along with the cylinder head, thereby preventing the residual pressure in the cylinders from suddenly pushing the cylinder head away. (III) Disassembly and inspection of piston components 1. Inspect and measure the clearance between the piston and the cylinder block. 2. Install the high-pressure oil tube fitting and high-pressure oil tube (or special wrench) at the connection nut between the piston rod and the crosshead. 3. Connect the other end of the high-pressure oil tube to the manual hydraulic pump. 4. Press the handle of the manual pump to raise the pressure to 145 Mpa ； Stay for 20-30 minutes. 5. Then loosen the piston rod nut and the piston rod to separate them from the crosshead. 6. Then install the piston guard; use a crane to lower the piston assembly and place it gently on the sleeper. (IV) Remove the crosshead of the compressor unit and measure the clearance between the crosshead and the slide. 2. Remove the crosshead pin gland. 3. Gently tap the crosshead pin with a copper rod and remove it. 4. Use a crane to lower the crosshead pin, and place it gently on the rubber mat. (5) Removing the compressor connecting rod: 1. First, remove the bolts on the crankcase cover, and then lift the crankcase cover using a crane. 2. Install the high-pressure oil pipe fitting and high-pressure oil pipe (or special wrench) at the rod bolt nut area. 3. Connect the other end of the oil tube to the manual hydraulic pump. 4. Press the handle of the manual pump to raise the pressure to 145 Mpa. 5. Loosen and remove the connecting rod nut and bolt (and make a mark). 6. Remove the connecting rod and place it on the rubber sheet (and make a mark). (VI) Removing the compressor main shaft 1. Remove the bolts of the upper bearing shell on the main shaft one by one, and then take off the upper bearing shell. 2. Check the radial clearance of the main shaft bearing shells. (Starting from the motor side) 3. Check the radial runout of the spindle journal. (Starting from the motor side) 4. Check the crank arm difference. 5. Lower the main shaft using a nylon sling and place it on the rubber mat. 6. Remove the lower bearing shells of the spindle one by one.

Since the working principle of a reciprocating compressor is to convert the motion of the crankshaft into reciprocating motion, the biggest drawback of its rotation is uneven rotation. This uneven rotation generates additional dynamic loads on the moving parts, increasing the load on the couplings and reducing their lifespan. It can also cause fluctuations in the current flow in the motor and throughout the entire plant. Therefore, a flywheel is used to ensure sufficient flywheel torque and a uniform tangential force; the energy stored during the rotation of the flywheel helps to buffer out fluctuations in the rotation angle of the piston-type reciprocating compressor.

Flywheels are further divided into inertia wheels; they have a large diameter and weight, which results in high inertia when rotating. It is this inertia that helps to compensate for the changes in torque of the prime mover caused by variations in the pressure of the compressor piston. This enables the piston to move evenly, while keeping the prime mover torque constant. As the piston moves back and forth, its acceleration changes continuously; as a result, the inertial force acting on the piston also changes constantly. Moreover, the pressure exerted by the gas on the piston is not uniform, which leads to fluctuations in the load on the motor. The function of the flywheel is to balance these loads on the motor.

Flywheels are further divided into inertia wheels; they have a large diameter and weight, which results in high inertia when rotating. It is this inertia that helps to compensate for the changes in torque of the prime mover caused by variations in the pressure of the compressor piston. This enables the piston to move evenly, while keeping the prime mover torque constant. As the piston moves back and forth, its acceleration changes continuously; as a result, the inertial force acting on the piston also changes constantly. Moreover, the pressure exerted by the gas on the piston is not uniform, which leads to fluctuations in the load on the motor. The function of the flywheel is to balance these loads on the motor.

Answer: Flywheels are also divided into inertia wheels; they have a larger diameter and weight, which results in greater inertia when rotating. It is this inertia that helps to compensate for the changes in torque of the prime mover caused by variations in the pressure of the compressor piston. This enables the piston to move evenly, while keeping the prime mover torque constant. As the piston moves back and forth, its acceleration changes continuously; as a result, the inertial force acting on the piston also changes constantly. Moreover, the pressure exerted by the gas on the piston is not uniform, which leads to fluctuations in the load on the motor. The function of the flywheel is to balance these loads on the motor.

1. The inertial force of the transmission enables the crankshaft and connecting rods to pass through the dead center smoothly and maintain normal rotation. 2. Inertial force can ensure the uniform rotation of the compressor. 3. The flywheel has an energy storage function; when the power of the prime mover is insufficient, the inertial force enables the compressor to continue rotating normally. 4. Its own weight helps to maintain balanced operation of the compressor and torque balance.