Hydrogen sulfide (H2S) gas is highly toxic and extremely pungent. It is a by-product of oil refining, commonly occurring when low-value, sulfur-rich residue is converted into more profitable commodities such as petrol and diesel. The Claus process is generally used to quickly convert this chemical into a substance that can be safely and easily transported. This process uses several oxidation steps to convert H₂S into harmless sulfur. And that is exactly what the Lotos refinery in Poland does. However, Lotos was concerned that the four existing Claus units would cause a bottleneck in the refinery as they would be unable to handle the increase in H2S volumes resulting from expansion plans. So Linde proposed a gas-enabled solution to debottleneck the refinery. The concept is based on the supplementary use of pure oxygen in the air oxidation step to increase H2S processing capacity.
30 percent increase in capacity
In summer 2014, application engineers from Linde ran a two-week trial on all Claus units at the Lotos refinery in order to verify the efficiency of oxygen enrichment. They used proprietary Linde hardware to meter and inject the oxygen with high precision. Linde’s Chemical Development & Services team contributed to the test phase by supporting sampling and analysis of the Claus process gas. The trial confirmed not only the projected benefits of oxygen enrichment but also enhanced contaminant destruction capabilities – while enabling a 30 percent increase in capacity.
Pressure Swing Adsorption unit generates oxygen
Successful completion of these proof-of concept trials confirmed the customer’s trust in Linde as the only company capable of offering the entire test phase from a single source. On examination of the test results, Lotos decided to integrate oxygen enrichment into regular operations. For this, Linde is delivering a containerised, turnkey Vacuum Pressure Swing Adsorption (VPSA) unit with a liquid oxygen backup solution. The on-site VPSA unit can generate three tonnes of oxygen per hour and is scheduled to go on stream in April 2017. It is envisaged that Linde will be looking after operation and maintenance as well as supplying the liquid oxygen for the backup solution. Lotos plans to connect its on-site unit to Linde’s Remote Operation Centre (ROC) to monitor and manage the plants. The VPSA unit for the Lotos refinery in Gdansk is the fourth in a series of projects that Linde Engineering has successfully delivered to support on-site oxygen enrichment of Claus units in refineries.
increase in capacity
with pure oxygen
Two of the four Claus units at the Polish refinery in Gdansk that are being engineered for increased capacity through oxygen enrichment.