New Approach to Process Gas Compression

Applications ::

Vacuum Distillation Units:

Case study 5: SINOPEC Tahe Refinery
Case study 6: API Ancona Refinery

Case study 6: Vacuum Distillation Unit at API Ancona Refinery, Italy


Application: Vacuum Distillation

System: Visbreaker vacuum system

Location: API - Ancona refinery, Italy


API decided to increase bitumen production capacity by installing a new Visbreaker Vacuum flash column. The limitations of inadequate soar water treatment and cooling water capacity were overcame by utilizing the unique Hijet vacuum system.


The use of conventional steam ejector system for the new column was considered prohibitively expensive because refinery had to overcome bottlenecks in the following utilities:

  • Sour water treatment capacity
  • Cooling water limitations


2-Stage VacComp system Diagramm

A two stage Hijet vacuum and compression was put into operation system at API Ancona refinery in February 2001 and has been in reliable service since. The first Hijector™ is mouinted to the side of the vacuum column without the necessity to build a separate structure. This reduces capital costs and required plot space.

The first stage pulls vacuum at the top of the column to 15mm Hg whilstthe discharge pressure downstream the second stage is 2 bara.

The system utilizes a single pump for both stages and LVGO as the motive liquid. The system also includes two separators, and one cooler.


API Hijector

Hijet vacuum system at API refinery does not produce soar water and has only 25% of cooling water requirement compared to a steam ejector system, whilst at the same time provides the following additional benefits:


  • Increased reliability,
  • No motive steam – reduced emissions,
  • No sour water production– reduced emissions,
  • Reduced operational expense compared with the steam ejector system.

The benefit of using the Hijet system is made clear by examining the data shown in the following table

ParameterSteam Ejector System & LRPHijet two-stage vacuum-compression system
Vacuum column pressure 15 mm Hg 15 mm Hg
Discharge gas pressure 1.5 bara 1.5 bara
Motive steam consumption 9.0 tons/h 0 tons/h
Cooling water consumption 639 m3/h 128 m3/h
Electric power Requirement 15 kW (LRP) 393 kW
Operation time (350days / year) 8,400 h 8,400 h
HP steam consumption / year 75,600 tons 0 T
CW consumption / year 5,367,600 m3 1,075,200 m3
Electric Power consumption /year 126,000 kWh3,301,200 kWh
Cost of HP steam / year EUR 756,000 0
Cost of cooling water / year EUR 161,028 EUR 32,256
Cost of electric power / year EUR 5,670 EUR 148,554
Total cost of utilities / year EUR 922,698 EUR 180,810
Minimum yearly direct saving 0EUR 741,888
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