ISO DIS 21905
Gas turbine exhaust systems with or without waste heat recovery
|Publication Date:||7 March 2019|
|ICS Code (Gas and steam turbines. Steam engines):||27.040|
a) This ISO standard specifies requirements and gives recommendations for the design, materials of construction, modelling, controlling, fabrication, inspection, testing, installation, start‐up and operation of GT Exhaust Systems with or without WHRU for use on‐shore or off‐shore in the petroleum, chemical and process service industries.
b) For the purpose of this Standard, the Exhaust System means all items in the turbine exhaust gas stream between the GT exhaust gas collector outlet flange and the termination to the atmosphere.
c) The following items are not covered by the scope of this Standard:‐
i. Heat Recovery Steam Generator equipment (HRSG)
ii. Supplementary fired systems see item e) below
iii. Auxiliary fired systems see item e) below
iv. Exhaust Gas Collector (also known as Exhaust Plenum) - see item f) below
v. Fire Detection and Extinguishing Systems - see item g) below
d) WHRU's exchange gas turbine exhaust heat into single phase heat transfer media, whilst HRSG's involve the evaporation of water into steam (a two phase steam mixture) and superheating of same. This difference adds significant complexity to equipment and system design, control, safeguarding, operation and construction requirements. Certain technical requirements contained in this standard are relevant to HRSG equipment and as such the Purchaser can identify and use those relevant clauses. However in considering HRSG products the Purchaser should address such complexities to ensure that all performance and operational requirements are met
e) GT Exhaust System (including WHRU) equipment covered in this standard is un‐fired. The inclusion of supplementary and/or auxiliary firing equipment and systems adds significant complexity to design, control, safeguarding, operation and construction requirements.
f) The GT exhaust gas collector is typically part of the GT scope of supply and accordingly is not covered in this standard. However certain technical requirements contained within this standard may be relevant to the collector and as such the Purchaser may choose to specify part/s of the standard as technical requirements for the collector supply. Note that both the GT collector and the Exhaust System form the hot gas path therefore considerations shall be given as to how these components are integrated. g) Where the Heat Transfer Media (HTM) is flammable, the Purchaser may specify if fire detection and/or extinguishing systems in the Exhaust System shall be supplied. However the requirements for such systems are not covered by this standard and shall be agreed between the Purchaser and the Supplier.
Note: A bullet (●) at the beginning of a paragraph indicates that either a decision is required or further information is to be provided by the purchaser at the Tender stage.