1.1 Purpose of Pipe Blowing
The blowing for the superheater, the reheater and the steam pipeline system of the boiler is an important procedure prior to the operation of the newly-built unit, for the purpose of clearing various sundries (e.g. sand grain, stone block, scraps and iron scale etc.) left in the superheater, the reheater and the steam pipeline during manufacture, transport, preservation and installation, preventing pipe bursting of the superheater and the reheater and damage on the turbine flow passage part during unit operation, raising the safety and economical efficiency of the unit and improving the steam quality during operation. It shall be stressed that pipe blowing may not eliminate all sundries and only serves as the last supplemental procedure, and accumulated sundries shall be first eliminated during manufacture and installation.
1.2 Main scope of pipe blowing
1.2.1 The superheater, the reheater and the system of the boiler.
1.2.2 Main steam pipe, the cold section pipe and hot section pipe of the reheat steam.
1.2.3 The high-pressure bypass system.
1.2.4 The steam source pipeline of the steam feed pump.
2 Quality Criterion and Parameter Selection of Pipe Blowing
2.1 Quality Criterion of Pipe Blowing
2.1.1 As required by 10.5.8 in "The Code of Erection and Acceptance of Electric Power Construction" (Section of Steam Boiler Set) (hereinafter referred to as Boiler Section): the pipe blowing coefficients of the superheater, the reheater and each section of the boiler shall be greater than 1; the target plate made with aluminium sheet shall be installed in the temporary steam exhaust pipe (or at the steam exhaust port) at the end of the blown pipe, with the width about 8% of the inside diameter of the steam exhaust pipe and the length straightly through the internal pipe size; on the premise of ensuring the pipe blowing coefficient, the target plate shall be replaced for successive two times for inspection, and blowing qualification shall be identified if the blackspot generated due to impact on the target plate is not greater than 0.8mm and the macroscopic blackspot is not more than 8 points.
2.1.2 While the two-section method is adopted for blowing, the reheater and its pipeline shall be blown and the blowing for them shall be qualified through inspection after the blowing for main steam pipeline is qualified. While the one-section method is adopted for blowing, the blowing qualities for the main steam pipeline and the reheat steam pipeline shall be separately inspected until to meet the criterion requirements.
Contents
1 Purpose and Scope of Pipe Blowing
2 Quality Criterion and Parameter Selection of Pipe Blowing
3 Pipe Blowing Modes and Methods
4 Installation of and Technical Requirements for Temporary Facilities
5 Key Implementation Points on Pipe Blowing Technology
6 Safety and Cautions for Blowing Operation
Appendix A Application of Differential Pressure Method in Pipe Blowing Technology
Appendix B Typical Structure of the Granula Collector
Appendix C Counterforce Calculation of the Steam Exhaust Pipe while Pipe Blowing
Appendix D Structure of Tandem-shaft Target Plate Device
