Reciprocating compressor with a pressure-drop chamber and method

Patent metadata

Field	Value
Publication number	US-12504009-B2
Application number	US-202218579904-A
Country	US
Kind code	B2
Filing date	Jul 15, 2022
Priority date	Jul 22, 2021
Publication date	Dec 23, 2025
Grant date	Dec 23, 2025

Abstract

The reciprocating compressor comprises a compressor frame, a crankshaft and a connecting rod, connecting the crankshaft to a crosshead. A piston rod connects a piston to the crosshead. The piston reciprocates in a gas compression cylinder. At least one pressure-drop module is positioned between the gas compression cylinder and a crosspiece guide. The piston rod extends from the gas compression cylinder through a pressure-drop chamber of the pressure-drop module. Also disclosed herein is a method of operating a reciprocating compressor.

First claim

The invention claimed is:

1 . A reciprocating compressor configured to pressurize process gas to a delivery pressure, the reciprocating compressor comprising:
a compressor frame with a crankshaft supported for rotation therein; a connecting rod connected to the crankshaft; a crosshead connected to the connecting rod; a crosspiece guide arranged to receive the crosshead therein; a piston rod having a first end coupled to the crosshead; a piston coupled to a second end of the piston rod; a gas compression cylinder comprising a cylinder body with an inner volume to receive the piston therein; a suction line coupled to the gas compression cylinder; a pressure-drop module positioned between the gas compression cylinder and the crosspiece guide, the pressure-drop module comprising a pressure-drop chamber; and a distance piece positioned between the pressure-drop module and the crosspiece guide, the distance piece comprising a first inner volume, wherein the piston rod extends from the gas compression cylinder through the pressure-drop chamber and the first inner volume, and wherein, in use,
the first inner volume receives process gas at a gas recovery pressure, and
the pressure-drop chamber receives process gas at a pressure lower than the delivery pressure of the process gas and higher than the gas recovery pressure.

2 . The reciprocating compressor of claim 1 , further comprising:
a first piston rod pressure packing positioned between the gas compression cylinder and the pressure-drop chamber.

3 . The reciprocating compressor of claim 1 , further comprising:
a first piston rod pressure packing positioned between the gas compression cylinder and the pressure-drop chamber; and a second piston rod pressure packing positioned between the pressure-drop chamber and the crosspiece guide, wherein the second piston rod pressure packing is positioned between the pressure-drop chamber and the distance piece.

4 . The reciprocating compressor of claim 1 , wherein the distance piece further comprises a second inner volume at ambient pressure.

5 . The reciprocating compressor of claim 2 , further comprising:
a first piston rod pressure packing positioned between the gas compression cylinder and the pressure-drop chamber; a second piston rod pressure packing positioned between the pressure-drop chamber and the crosspiece guide; and an intermediate piston rod pressure packing, wherein the distance piece further comprises a second inner volume at ambient pressure, wherein the intermediate piston rod pressure packing is positioned between the first inner volume and the second inner volume, and wherein the first piston rod pressure packing, the second piston rod pressure packing, and the intermediate packing are dry pressure packings.

6 . The reciprocating compressor of claim 1 , wherein the pressure of the process gas is around a suction pressure in the suction line.

7 . The reciprocating compressor of claim 1 , further comprising:
a fluid connection line coupled to the suction line and to the pressure-drop chamber, wherein, in use, the pressure-drop chamber receives process gas at around a suction pressure in the suction line.

8 . A method of operating a reciprocating compressor, the method comprising:
on a reciprocating compressor comprising a crankshaft supported for rotation in a compressor frame, a crosshead, a crosshead guide for receiving the crosshead, a connecting rod connecting the crankshaft to the crosshead, a piston rod coupled to the crosshead on a first end, a piston coupled to a second end of the piston rod, a gas compression cylinder comprising a cylinder body with an inner volume to receive the piston, and a pressure-drop module positioned between the gas compression cylinder and the crosshead guide, the pressure-drop module comprising a pressure-drop chamber formed therein, and a distance piece disposed between the crosspiece guide and the pressure-drop module, the distance piece comprising a first inner volume rotating the crankshaft; converting the rotary motion of the crankshaft into a reciprocating motion of the piston in the gas compression cylinder; sequentially sucking process gas at a suction pressure in the gas compression cylinder and discharging process gas at a delivery pressure from the compression cylinder; allowing process gas in the first inner volume to flow to a flare stack; and purging the pressure-drop chamber with process gas at a pressure lower than the delivery pressure of the reciprocating compressor and higher than the pressure in the first inner volume.

9 . The method of claim 8 , wherein the pressure-drop chamber is purged with process gas at a pressure around the suction pressure.

10 . The method of claim 8 , further comprising: maintaining the first inner volume of the distance piece at a pressure around ambient pressure that is lower than the pressure of the pressure-drop chamber.

11 . The reciprocating compressor of claim 1 , wherein an intermediate piston rod packing is located between the first inner volume and the second inner volume of the distance piece.

12 . The reciprocating compressor of claim 1 , further comprising:
an oil wiper packing positioned between the second inner volume and the crosshead guide.

Assignees

• Nuovo Pignone Tecnologie Srl

Inventors

• Bassani Simone
• Chiesi Francesco
• Batini Niccolo′
• Bargiacchi Massimo
• Tenze Andrea
• Cangioli Francesco

Classifications

• F04B39/041

  sealing for a reciprocating rod (sealing in general F16J) · CPC title

• F04B39/0022

  piston rods · CPC title

• F04B35/01

  the means being mechanical · CPC title

• F04B25/02

  of stepped piston type · CPC title

• F04B39/128

  Crankcases · CPC title