Steam superheaters (SNG)

Efficient Superheating with Low-Stress Tube Sheet Design

A high degree of superheating of the high-pressure steam is essential for the thermal efficiency of the SNG process. The process gas is controlled to leave the waste heat boiler (WHB) at a high temperature and the steam superheater (SHH) converts the process gas heat to highly superheated steam.

The Topsoe SSH for SNG is designed to allow for both the high temperature of the process gas and the high temperature and high pressure of the superheated steam. The SSH is of the bayonet type – a unique design which ensures that the design temperature of the tube sheet can be kept at the lowest possible level. This is advantageous for two reasons: Firstly, the construction material of the tube sheet can be of a well-known, well-referenced low alloy type and secondly, the thickness of the tube sheet will be significantly lower than in other designs. Furthermore, the bayonet design ensures that thermal stresses due to temperature differences from the steam inlet side to the outlet side are eliminated – leading to a high degree of equipment reliability.

Benefits

• The unique Topsoe steam superheater for SNG makes it feasible to obtain a high superheating temperature, leading to a superior overall energy efficiency of the SNG plant

• The superheater is designed with construction materials that are selected to match the conditions on the process gas side as well as on the steam side and at the same time optimized to lower the cost and equipment weight

• Robustness and reliability is inherent in the Topsoe SSH

• The manufacture of the steam superheater for SNG follows the same requirements as prescribed for our remaining portfolio of high-quality equipment sustaining challenging operating conditions