Second stage of rectisol unit intensification

The objective of the Rectisol unit (elaborated by the company Lurgi) is to produce energogas from crude generator gas. This is accomplished by washing crude gas by methanol at pressure of 2,0 – 2,6 MPa at low temperatures. Washing takes place in absorption columns. At washing, the following components of the crude generator gas are excised or modified: humidity, H₂S (hydrogen sulphide), CO₂ (carbon dioxide), NH₃ (ammonia), HCN (hydrogen cyanide), resinous-forming substances and high-order hydrocarbons.
Waste gases are processed in the following way: BEP in the WSA unit (H₂SO₄ production). CHEP are lead off to a heating plant. Isolated crude petrol from the separators is repumped back to processing to the Rectisol unit and together with other petrol is after methanol extraction drained away into storage tanks. Waste water is drained away for the biological waste water treatment plant. Methanol is returned back into the process.

The base of the technology are two purifying Rectisol lines. The source of the coldness for the technology are four lines of Linde refrigeration devices, mutually joined in the absorption and boiling up parts and organizationally divided into two lines.
Each purifying line is able to work independently and produce energogas with H₂S concentration of 0 – 36 mg/m³ (n) and contents of CO₂ according to the required degree of CO₂ washing.

Considering the condition and detrition of the device, the lines were capable of processing max. 115 000 Nm₃ each. Before reconstruction, they each processed 100 000 Nm₃ on average.
The objective of the reconstruction was to design a technological solution which would enable restoration of the original processing capacities of gas purification so that each Rectisol unit processes 130 000 Nm₃/h at output gas pressure at the end of the lines of 2,21 MPa.


Range of activities:

• Project for the building permits – elaborated for both lines.
• Specification documentation – elaborated for both lines.
• Implementation documentation – only II. phase, line nr. 2
• Only II. phase, line nr. 2 was executed.

Subjects of the II. stage adjustments on the production line nr. 2 were:

• Replacement of the existing 2D1 train for a new more efficient train including separator
• Replacement of the built-ins and floors in the existing 2D70 train
• Floor dissasembly in the existing 2D40 train
• New 2E40 exchangers connection
• Decommission and disassembly of the 2E74 exchanger
• Replacement of the existing 2G80 R, N pumps for new more efficient ones
• Flow-meters, regulatory valves and keys were replaced for new ones with a lower pressure loss.

Parts of the delivery were: Mechanical part, Management systems for technological processes part, Electro part, Construction/ erection part including steel structures.