Thermocouple For Sulfur Recovery Unit (SRU)

Sulfur Recovery Unit (SRU) is used for conversion of Hydrogen Sulfied (H₂S) into elemental sulfur or a valued product. In petroleum refineries, H₂S is formed due to various chemical processes which is also termed as ‘sour gases. SRU also ensures that there will be permissible discharge of H₂S in the atmosphere so air pollution will be lesser. The conversion process in a SRU is termed as ‘clause processes. Once the elemental sulfur extracted, the remaining toxic gases may burn out.

Claus Process In A Sulfur Recovery Unit:

In the claus process, a thermal reaction is performed which involves burning of toxic H₂S in the presence of oxygen so that SO₂ and water are formed. Hence, after it SO₂ and remaining sour gas are reacted through a catalyst and elemental sulfur is obtained. Main parts of any SRU to perform claus reaction includes a fire burner for combustion of H₂S, catalytic reactors for effective reaction between SO₂ and H₂S, a condenser for steam vaporisation and a tail gas treatment unit. The fluid of any SRU may be sour acid gas or vapour or a combination of Flue and Acid gas that may contain about 90% of H₂S. The working temperature is about 1250 ̊C to 1500 ̊C and the pressure may be about 1Kg/cm2. As the temperature is on higher side so noble metal thermocouples are used for the measurement of temperature of any SRU.

Thermocouple For Sulfur Recovery Units:

Tempsens offer noble metal high temperature sensors (thermocouples) for SRU applications. These thermocouples are of S-type/R-Type/B-Type depending upon the working temperature in simplex or duplex configuration. A general layout of any SRU thermocouple contain Ex-proof terminal head (MOC:LM6/SS grade), thermocouple element with insulating, inner and outer ceramic tubes, a flange for the connection in the process, a metal holding for proper mounting of ceramic tubes, a glass sealing below the terminal blocks and an air purging unit embedded in the holding tube. Tempsens also offer the SRU with inner tube as ceramic KER-710 and outer tube as sintered alpha silicon carbide or Hexoloy.

Purpose Of Purging Unit and Glass Sealing:

As these outer and inner ceramic tubes are porous in nature so toxic gases inside the process may enter in sensor and may harm the platinum element or may came out through head so SRU thermocouple is supplied with a constant purging system hence the impact of invasive gases can be neutralized. The purging medium may be air or nitrogen depending upon the client’s requirement and process temperature. This purging arrangement should be such that its pressure is kept higher than the internal process pressure therefore oxidation of thermocouple can be prevented and a fair life of thermocouple is obtained.

Glass sealing arrangement is done so as to reduce the possibility of any mishappening if inner or outer ceramic tube break. The glass sealing act as a boundary wall in order to stop the internal pressure to come out from the terminal head.

Technical Specifications of Tempsens SRU Thermocouple:

Conclusion:

SRU is an essential part to obtain the elemental sulfur from toxic H2S / sour gases of refinery. Accurate temperature measurement of sulfur recovery unit is necessary in any petrochemical refinery for smooth operation of furnace refractory. Tempsens offer noble metal thermocouples with ceramic tube and purging unit with a variety of technical specifications as per the client’s requirement.