WD valves for a CO₂ compressor: 8,000+ hours without failure

A coal-chemical plant in Shandong was operating a 4M40-150/80 reciprocating carbon dioxide compressor whose original valves had a short service life and high energy consumption. RONDER selected WD-type mesh valves and carried out dynamic calculations, engineering design and drawing checks. After the redesign, the valves achieved at least 8,000 hours of continuous operation without failure.

The fourth-stage valves are the example below for how flow capacity and valve plate motion were worked out.

What should be checked in a CO₂ compressor valve?

Short valve life means more maintenance and spare-parts work. The redesign aimed to extend running time and cut valve pressure loss. We looked at three things.

Flow area and pressure loss

Each stage has different gas density and flow, so each needs its own calculation. Check the seat, the opening under the lifted plate and the guard passages. If the seat or guard already restricts flow, a higher lift adds little.

Valve plate impact and fatigue

Impact energy rises with the square of impact velocity, so plate mass, material and contact geometry matter as much as lift.

Opening and closing timing

Late closing causes reverse flow and harder seating, and rebound adds more impacts. Lift and spring must match the gas force through the cycle, including at loads away from the design point.

Factors affecting flow resistance, valve plate lift and impact dynamics in a CO2 reciprocating compressor valve

Factors affecting flow and motion in CO₂ reciprocating compressor valves.

WD valve selection and redesign

Selecting the valve type

WD-type mesh valves have wide slots, provision for relatively large lift and substantial springs. The design selected for this project used the type’s relatively high flow capacity and low plate impact force.

WD suits higher-molecular-weight gases at low to medium pressures and speeds, lubricated or oil-free. See the WD valve page.

Dynamic calculations and parameter matching

The fourth-stage valves were used for the dynamic calculation example. One-dimensional unsteady motion analysis can calculate plate lift, velocity, and opening and closing times throughout the operating cycle to assess delayed closing, rebound and impact.

Inputs include actual speed, cylinder data, suction and discharge conditions at each stage, gas properties and valve geometry. We check opening and seating impact velocity separately against the material, contact geometry and service conditions, and look at loads away from the design point too.

Increasing lift usually enlarges the flow area beneath the plate, but it also lengthens plate travel and may increase impact velocity. Lift, moving mass and spring load were matched to meet flow requirements while maintaining stable valve motion.

Engineering drawings and field validation

After the dynamic calculations, engineering drawings were prepared and checked to define the valve structure. The workflow below shows the steps of the redesign.

RONDER CO2 compressor WD valve workflow for dynamic analysis and engineering redesign

RONDER reciprocating compressor valve dynamics and redesign workflow.

Field operating result

The redesigned WD-type valves achieved at least 8,000 hours of continuous operation without failure.

For valve selection in a different gas service, see the WP valve redesign case for a chloromethane compressor.

Send RONDER a valve redesign enquiry

OEMs can supply design data for new equipment; plant teams can supply operating data and details of existing valve problems. Send the following information to sales@ronder-valve.com:

Company name, contact details, and whether the enquiry concerns new equipment or a redesign.
Compressor model, stage, speed and valve installation dimensions.
Gas composition, suction and discharge pressures and temperatures for each stage, and actual load.
Current problems, valve operating hours and any photographs of failed parts that you can share.

Say whether pressures are gauge or absolute. If you don’t have everything, start with the compressor model, operating conditions and main problem.

If the same stage keeps failing, also tell us about liquid carryover, contaminants, lubrication and load changes.