During the operation of the compressor, the piston rings, support rings and piston rod packing rings are the core components that ensure the sealing performance and stable operation of the equipment. The rationality of their design and the standardization of installation directly affect the working efficiency, leakage and service life of the compressor. This article will comprehensively disassemble the core technical details of the three types of components from three dimensions: function, design key points, and installation requirements, providing practical operation guidelines that industry practitioners can directly refer to.

1. Core Function Analysis

The functions of piston rings and support rings: Piston rings are used to seal the high-pressure gas in the cylinder to prevent it from leaking through the gap between the piston and the cylinder. The support ring serves to support and guide the piston. Strictly speaking, for a horizontally arranged cylinder, the support ring supports the weight of the piston and half of the piston rod, while the weight of the other half of the piston rod is supported by the crosshead. All compressors except the upright labyrinth piston must have support rings.

2. Key design considerations

3. Factors to be noted in the design of non-metallic support rings:

In an oil-free lubrication structure, the specific pressure borne by the non-metallic support ring shall not exceed 0.035MPa. This value is obtained by adding half the weight of the piston rod to the total weight of the entire piston assembly and then dividing by the 120° projected area of all support rings. (2) In oil-lubricated structures, according to the same criterion, the specific pressure borne by the support ring shall not exceed 0.07MPa.

4. Installation requirements for piston rings and support rings:

When installing the piston rings and support rings, the axial clearance should be checked. (2) Care should be taken to avoid excessive force causing breakage. (3) Impurities and dust in the cylinder should be carefully cleaned in advance. When multiple piston rings are installed, the notches of each ring must be staggered from one another. When installing two-petal or multi-petal piston rings, they should be installed in groups one by one, and attention should be paid to the combination sequence of each petal of each group of rings, "1" to "1" or "." "Right." " . (6) The installation of the support ring for the integral ring structure should be carried out by heating. Special transition cylinders, boost rings and rubber hammers must be prepared. Two to three people should cooperate to operate to prevent breakage or incomplete installation. There should be no looseness between the rear ring and the bottom diameter of the piston groove after installation.

5. The function of the piston rod packing ring

The piston rod packing ring is mainly used to seal the gap between the cylinder seat and the piston rod, preventing gas from leaking along the direction of the piston rod.

6. The influence of piston alignment and radial runout of piston rods: Poor piston alignment or excessive radial runout of piston rods can cause uneven wear between piston rings and packing rings, increasing leakage and shortening service life.

7. Factors to be considered in the design of piston rod packing rings

Intake and exhaust pressure; (2) Intake and exhaust temperatures; (3) Piston rod diameter; (4) Piston rod material and surface roughness; (5) Heat treatment and coating conditions on the surface of the piston rod; (6) Compressor speed and stroke; (7) Gas composition and exhaust volume; (8) The cylinder is lubricated with oil or without oil. (9) Structure and form of the stuffing box.

8. Installation requirements for piston rod packing rings:

Piston rod packing rings are mostly three-petal structures (there are also six-petal and other forms). During the manufacturing process, they are cut from a single piece and marked before cutting. When pairing, they should be "1"; to "1", "2" to "2" or "" to"." .

(2) The single-acting ring assembly consists of a radial cut ring and a tangential cut ring. When installing it into the packing box, it should be noted that the radial cut ring must face the high-pressure side. (3) The marked side of the packing ring should face the high-pressure side.

(4) For single-acting ring groups with flow-blocking rings, it is necessary to distinguish between the radial cut ring on the high-pressure side and the flow-blocking ring on the low-pressure side.

9. The "three clearances" of the piston rod packing ring:

(1) Axial clearance: Ensure that the packing ring can float freely in the ring groove; otherwise, it will not work properly.

(2) Radial clearance: To prevent the packing ring from being compressed due to the settlement of the piston rod, thus avoiding deformation or damage.

(3) Cut clearance: It is used to compensate for the wear of the packing ring.