ADVANTAGES OF MODULAR APPROACH TO GAS PROCESSING

Comparative review of associated petroleum gas dehydration processes. RN-Yuganskneftegas unit is being used as an example.

Active incorporation of modular approach to gas processing and treatment into design, production and installation has been used worldwide since 1980’s

This approach was brought on by the inability to conduct installation and construction in the traditional way during off-shore applications. Currently, modular equipment approach is a world-wide practice among gas processing industry as a whole both on- and off- shore 

Common practice in Russia is to design and construct a separate foundation for each piece of equipment within the plant territory with further field installation of required cabling and pipelines. Modular approach implies division of the whole process train into several large blocks or modules, inclusion of lesser elements into these major modules at the design stage with further modules manufacture within the controlled environment of the vendor’s workshop.

While comparing different cases of plants being constructed using either traditional or modular approach it may be easily notices that the latter requires far less time and capital expenses than the former.

The following table contains the facts to support this.

1. Shorter Project implementation schedules Shorter design lead times. In essence all of the connecting cables and infrastructure design parts are excluded. The overall process design is simplified to a diagram with a number of ‘black boxes’ – modular process blocks.
Design is generated in parallel to placement of the production orders with the vendors – fast tracking.
Significant reduction of construction and installation times due to smaller number of individual foundations, less welding, piping and cabling in the field.
Lesser risk of construction and installation prolongation (e.g. from bad ambient conditions or lack of electric power on the site).
2. Project cost reduction Smaller amount of design
Lesser amount of construction and field installation
3. Higher quality Cabling and piping design is done by the vendor – a more specialized company which is therefore able to allocate expert engineering resources in comparison to general resources of the design company.
Large amount of installation is done at a controlled environment of the vendor workshop by expert engineers that specialize in this particular installation instead of an uncontrolled field environment by general installation workers.

The counterarguments are often voiced by opponents that contend the main advantages of modular approach – speed and financial efficiency.

The designers are puzzled by fast tracking the design and order placement and also by the ability to remain in conformance with resolution #87 without detailing the process modules in excess of the common sense.

The construction workers cannot swallow the fact that the cost of their services is far less than commonly accepted 25-30% of the equipment cost.

It is typical that the three main contractors in a project are the design company, the procurement company and the construction company. In the reality of Russian projects, modular approach spells a significant decrease of functional involvement of the former and the latter and a consequent reduction of their income. At the same time the role and the fees of the procurement company is drastically increased turning it into a crucial and critical leader of the project.

An example of the modular approach – construction of the modular glycol dehydrator by ООО «RN-Yuganskneftegas», Uvatskaya group of fields

Glycol (Triethylene glycol - TEG) dehydration unit 40700 scm/hour (357 mln. scm/year) capacity, water dew point temperature minus 20 0С.

A comparative analysis of dehydration unit solutions

fig.1 «Traditional approach»

fig. 2 «Modular approach»

Equipment scope and design pattern

Equipment lifecycle comparison

  • Modular dehydration unit is completely assembled at the factory workshop. A complete factory testing procedure greatly reduces the risk of failures further on.
  • Modular approach concentrates liability and commitment for decision making within a single contractor (in case of the dehydration unit for NIPI NGH the responsibility for technical parameters of the unit lies with the designers of the unit).