Increasing throughput and reducing energy for gas processing plant

06 August 2013

Emerson Process Management’s support services have helped the MOL Group to increase throughput, improve product quality and reduce energy usage at its Algyõ gas plant in Hungary.

Control loop audits, advanced process control project management, and model predictive control project support, have helped the company achieve savings of over 9 million Euros since 2006. The gas processing plant in question is able to process up to 12 million cubic metres of gas every day and includes three columns on each of the two distillation column trains.

"Exploration and production projects are playing an important role in MOL Group’s portfolio, and for these we need good partners. The co-operation between MOL and Emerson has resulted in great achievements, since distillation columns involve highly interactive, multivariable processes that are difficult to control," said Károly Oláh, production manager at MOL. "Emerson has completed a number of major projects at our plant that have enabled significant reductions in process variability, provided large energy savings and reduced emissions."

The relationship between the two companies started in 2006, when MOL Group employed consultants from Emerson’s Control Performance Service to carry out a detailed audit of control loops, valves and instruments to identify areas requiring maintenance, replacement, tuning or redesign. The improved control loop performance reduced the variability of key process parameters by 84 per cent. Loop optimisation also reduced re-boiler duty and heating requirements, saving 670,000 euros per year in natural gas equivalent and cutting CO2 emissions by 4.3%.

In 2007, as part of an on-going energy-saving initiative, the company upgraded the plant’s DCS to a DeltaV digital automation system, and the following year Emerson performed further Control Performance Service work on the related Oil Absorption Plant. These enhancements stabilised the hot oil cycle system and improved the operation of the de-ethaniser column.

In 2009 MOL took advantage of the system’s embedded advanced process control capabilities by adding Emerson’s SmartProcess Distillation Optimiser which enables model predictive control for distillation columns and has yielded further benefits including better control of the product quality – which in turn enabled MOL to further decrease costs by reducing the quantity of product blending required.

The most recent project at the plant was a performance audit of the model predictive control based on MOL’s current operation and plant operating objectives. Suggested changes included modifying the structure of the regulatory control scheme; introducing a new component to the model predictive control scheme to better predict and account for impurities; and updating the procedure for using laboratory data within the calculations.

The changes made at the plant have also reduced the site heat load, which prompted the company to look at how best the heat supply can be managed for the whole site. Emerson is supporting this project with a study to evaluate the heat balance across the site, as well as the heat loads on the furnace. Emerson’s support will include designing and implementing the recommended modifications.

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