2021 ERTC Conference Newspaper - Day 1

ERTC 2021

Energy efficiency: project optimisation through proven tools and practices


the improvement in thermal performance.

The world’s refining sector is at a piv- otal inflection point where operators must evolve to remain competitive following a challenging year. Net-zero targets have also brought on aggressive decarbonisation goals that require critical action to meet the fast-approaching deadlines. Refineries will want to maximise the use of existing assets while minimising capital expenditure (Capex) and operating expense (Opex). While there are multiple pathways to achieve these goals, we will focus on two: refinery repurposing and refinery optimisation. Refinery repurposing We have already witnessed a few refiner- ies in Europe take the path of repurpos- ing facilities to produce biofuels. Fluor recently completed the front-end engineer- ing design (FEED) and detailed engineer- ing for a refinery project where the client wanted to repurpose their existing facil- ity to produce renewable diesel and meet incentive eligibility for tax benefits. A tai- lored plan was made which supported the project’s highly accelerated schedule with safe construction and in alignment with the client’s economic model. It was a plan that struck the right balance between sched- ule reduction, quality requirements, and capital investment. Developing quality deliverables that could be adapted for late changes was deemed the best approach, and this approach was supported by and founded on a highly col- laborative execution model with attractive incentives to stimulate achieving goals. During execution, several challenges asso- ciated with fast-track execution were over- come by applying practical and smart approaches such as a system of mini model reviews for early construction work fronts, designing using in-house data (vendor data was late), overdesigning certain founda- tions and steel members to meet the ultra- fast schedule, and collaboratively working with the constructor to address late design changes in the field. It cannot be highlighted enough that the way the Fluor team worked in harmony and partnership with the client and other stake- holders made the difference. This creative and highly collaborative approach helped achieve a 10-month FEED plus detailed engineering schedule – a six-month reduc- tion from the base case – which will help the client to generate an internal rate of return of 20-30% for the project. Refinery optimisation Energy efficiency optimisation reduces a facility’s required energy consumption, which mutually delivers decarbonisation benefits and provides an economic return. One technique to improve energy effi- ciency is to enhance heat integration and optimise the design of heat recovery equip- ment. This technique can create a huge economic benefit to any operating company and greatly helps in reducing CO 2 emis-

sions. We will discuss this further in the fol- lowing three examples:

Base case Future case

Exchanger composite heat curves This second case shows the importance of heat integration studies and involves the revamp of an existing crude distillation column. The client wanted to increase the recovery of distillates by installing a new vacuum flasher to recover the vacuum gas- oil (VGO) from the bottom stream off the crude column. In the original design, the VGO stream was cooled using a steam generator. Fluor began looking at opportunities to recover this heat by integrating it with the crude preheat train. Using composite heat curves, the team was able to better understand the heat transfer system and improve the design. By removing one low duty heat exchanger and installing a new VGO cooler, a higher furnace inlet temperature could be achieved while still saving 25 MW of furnace duty (see Figure 1 ). With a car- bon tax of 50 $/t of CO 2 , the simple invest- ment payback is three years. Heat integration in a crude/vacuum unit The third example showcases the results of a feasibility study that Fluor performed for a European refiner. The objective was to maximise throughput in the operating crude distillation unit (approximately 60% higher volumetric throughput) and the vac- uum distillation unit (approximately 40% higher volumetric throughput) while improv- ing VGO recovery at the expense of vac- uum residue and without increasing scope in key equipment. The goal was achieved by: • Plotting detailed heat exchanger com- posite curves to identify gaps in heat integration • Adding new, efficient heat exchangers to fill in those gaps • Improving the vacuum on the vacuum dis- tillation unit column Adding the heat exchangers created a higher total pressure drop in the crude pre- heat train, which resulted in the need for revamped pumps.

Crude rate, Sm 3 /h

1.6X 259 365 35.4 35.7 418 13.3

Heat exchanger design optimisation In this first example, Fluor takes a system- atic, rigorous approach to understand the client’s existing assets and needs. By lev- eraging our technical expertise in process and electrical engineering, we can readily determine the best options for each pro- ject and facility. The client’s original heat exchanger design was based on the traditional approach with high fouling factors and overdesign margins. Fluor studied a fit-for-purpose solution to reduce the fouling tendency and increase the heat exchanger’s effectiveness. The “modern - no foul” design approach manip- ulates and adjusts key design parameters such as velocity and shear force, impinge- ment rods, and tube wall temperature. As shown in Table 1 , reducing the sur- face area resulted in reduced Capex, while increasing the velocities in the shell and tube side resulted in higher equip- ment thermal efficiency. Additionally, the run time between cleaning cycles was increased, which ultimately reduced the fouling tendency. Although this activity comes at the expense of increased pres- sure drops, the loss in energy efficiency is well compensated and recovered by

Crude heater inlet temperature, °C Crude heater outlet temperature, °C

222 340 25.2 337 398 9.0

Crude heater duty, MW

Vacuum heater inlet temperature, °C Vacuum heater outlet temperature, °C

Vacuum heater duty, MW Total heater duty, MW

34.2 48.7 Specific energy consumption, MW/Sm 3 /h 34.2 / X 48.7 / 1.6X = 30.4 / X

www.ofgem.gov.uk/gas/retail-market/monitoring-data-and-statistics/ typical-domestic-consumption-values (10th June 2018)

The figure above shows that the spe- cific energy consumption of the crude distillation unit and the vacuum distilla- tion unit decreased by 11%, which indi- cates lower energy consumption as well as reduced emissions in the fired heaters. This investment was recouped in less than two years. Proven Tools and Practices Fluor’s role in energy transition is to safely design, build and maintain pro- jects that create a better, more sustain- able world. Our experience in this space is extensive, with the world’s top minds and technologies as well as a passion for innovation. Using proven tools, Fluor can optimise a project or facility’s energy effi- ciency to meet economic and environmen- tal needs. 11%savings in refinery natural gas import is equivalent to heating an average of 4000 homes every day inWestern Europe!




approach with fouling factors

fouling factors

with design margin

No, shells

4 (2p/2s)

2 (1p/2s)

1308 (4 x 327)

904 (2 x 452)

Surface area, m 2

Rel, cost, %

100 549


Clean overall coeff, W/m 2 K


Weight, kg

4 x 13,500

2 x 23,000

Shell side Pressure drop, kPa



Velocity, m/s



B-flow fraction, -



Tube side

(19.05 mm)

(25.4 mm)

Pressure drop, kPa



Velocity, m/s

0.85 1.45


Shear stress, Pa


Table 1 Traditional heat exchanger design versus modern approach

Contact: Ana.Casablanca.Jimenez@fluor. com



Composite curveWO pinch

Composite curve

Very low preheat duty






250 300






Cold side Hot site A team Hot site B team

Cold side Hot site A team Hot site B team



Furnace inlet temperature increase





0 20






140 160


0 20






200 180 140 160

Preheat duty (MW)

Preheat duty (MW)

Figure 1a Removed exchanger; 1b After solution implementation


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