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eVCP FOR RECIPROCATING COMPRESSOR BEST EQUIPMENT UTILIZATION WITH FULL AUTOMATION

eVCP FOR RECIPROCATING COMPRESSOR BEST EQUIPMENT UTILIZATION WITH FULL AUTOMATION

November 12
12:18 2016

eVCP FOR RECIPROCATING COMPRESSORS BEST EQUIPMENT UTILIZATION WITH FULL AUTOMATION

By: HOERBIGER Compression Technologies

eVCP MAXIMIZES COMPRESSOR OUTPUT …

Getting the maximum production output from a compressor directly results in money in the operator’s pocket.

To visualize what the additional compressor capacity provided by Evcp results in, here is an example:

  • The compressor’s nominal flow without eVCP is 7 MMSCFD (million standard cubic foot per day).
  • The gas contains 80% dry natural gas, 10% natural gas liquids (NGL) and 10% nitrogen.
  • Assume the natural gas price stays constant at $ 2 per MMBTU (million British thermal units) for dry natural gas and at $ 5 per MMBTU NGL.

eVCP eliminates the production losses caused by clearance pocket load steps of one compressor by continuously adjusting its capacity to the driver’s torque limit. The resulting increase in production accounts for 0.7 MMSCFD (million standard cubic foot per day).

The additional revenues per day: $1,500

In 5 years, the additional compressor output could result in

over$ 2,500,000

 of potential natural gas sales.

… AND SAVES OPERATING EXPENSES (OPEX).

“We achieved 10% improvement in throughput with eVCP. We can shut down 1 out of every 10 machines.”

Customer quote

 Save Maintenance Operation Costs and Maintenance Expenses

 A total increase in production might not always be desired or feasible. However, boosting throughput on a number of machines might free up one or more that can be shut down while still keeping overall production at the same level.

Freeing up an asset can result in a number of benefits. For one, operating expenses are reduced by the costs the shutdown compressor would generate for operation and maintenance.

Increase Capacity Where it’s needed

Second, a freed-up machine can serve as stand-by compressor or continue its service at a different site that benefits from increased throughput as mentioned.

TRADITIONAL CLEARANCE POCKETS MAKE OPTIMIZATION DIFFICULT

Effective compressor utilization at variable flowrates and variable gas pressures usually requires some combination of manually variable clearance pockets, fixed pneumatic clearance pockets, and valve unloaders.

 Switching between different clearance volumes (1) sets the compressor load and hence the output. Yet, even if every cylinder is equipped with a clearance pocket, there is always a gap between the real load curve the compressor is operating at (2) and the ideal one defined by the torque limit of the driver (3).

 In addition, traditional variable-volume clearance pockets need to be adjusted manually when the compressor is shut down. Manual adjustments on running equipment are risky for both the machinery and the operators. As a result, optimization adjustments occur infrequently or not at all. Incorrect selection of load steps can also lead to driver failure, loss of rod load reversal and major damage of crosshead and connecting rod.

 

Manual clearance pockets

 eVCP – MOVING OUTPUT TO THE MAXIMUM

“I witnessed first hand the dawning of a new day in compressor technology.” Satisfied customer, USA

 eVCP, an all-electric, automated stepless clearance pocket system, adjusts the real load (1) to the torque limit (2). By utilizing the full potential of the equipment, it always delivers the maximum output possible (3) at varying pressure levels, resulting in higher production rates.

eVCP installed on a compressor

 SIMPLE DESIGN

eVCP provides automatic load control compared to manual clearance pockets. A self-locking design eliminates power consumption during stand still.

 eVCP consists of a motor driven actuator which extends and retracts a piston to dynamically vary the clearance volume in a cylinder clearance pocket. The piston is stroked by a threaded spindle driven through a high reduction gearbox. The gearbox is oil-filled, with a lip-seal separating the gearbox from the spindle housing.

The key technology of eVCP is the heavy duty spindle with optimized screw thread geometry. The counter part of the spindle is an innovative hybrid nut with excellent tribological characteristics thanks to a high performance polymer material. The special composition of this polymer makes it possible to run without lubrication The spindle threads are designed to be self-locking, so there is no standby power consumption when the piston is not in motion. A manual handwheel can also be used to adjust the unit in the event of power loss.

The current position of the piston and therefore clearance volume can be checked through the inspection window, independent of the position sensor. Standardization allows for disassembly and re-assembly in the field, without special tools or training.

EASY TO HANDLE

Although far more advanced than conventional clearance pocket solutions, implementing eVCP is exceptionally easy.

 The operation of the unit is monitored through several sensors which are housed in the instrument cluster above the spindle housing. The information from these sensors is sent to the customer control system through a prewired connection cable supplied with the unit.

eVCP is controlled by activating the eVCP motor unit in the desired direction to increase or decrease output as the plant demands: Clockwise rotation retracts the eVCP piston, adds clearance and reducing compression capacity. Counter clockwise rotation extends the eVCP piston, reduces clearance and increases compressor capacity.

Typically, one or two eVCP systems are installed per compressor at the head ends of the cylinders, compared to a

combination of fixed volume clearance pockets or manually operated variable clearance pockets.

The compressor control system is constantly monitoring  the parameters of the machine (load, flow, line pressures) and depending on the desired control action, determines whether to add or remove clearance from the cylinder through simple forward/ reverse commands to the eVCP. The result: No more manual adjustments, and no more lost output.

For Complete article please visit view online link…….

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Engineering Horizons

Engineering Horizons

“Engineering Horizons” is the first & leading technical magazine of Pakistan covering Process, Mechanical, Metallurgical, Mining, Electrical & Electronics field under a single cover. We also feel pleasure in saying that this is the only magazine of its own kind & style, which is widely circulated in all Engineering Sectors of Pakistan.

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