1 General provision
1.0.1 Flow duct of circulating water pump house in fossil fuel power plant ( hereinafter referred to as flow duct) and its arrangement are important components of water system, this code is established with a view to ensure safety and economical operation of circulating water pump, as well as economize investment for capital construction.
1.0.2 This code is applicable to hydraulic design of flow duct with single pumping capacity is 9000- 45000 m3/h, flow duct with flow is larger than 45000 m3/h may be used by referring to this.
1.0.3 In order to prevent sundries flow into the flow duct to influence stream condition inside the flow duct, design for water catchments shall pay attention to adopting three preventions (floater prevention, sand prevention and ice slush prevention) measures. In river, lakes, and seas, it adopts open type water catchment’s mode and when water area is too wide and wave is too large, it shall consider furlong prevention measures.
1.0.4 Arrangement forms of flow duct shall be combined with hydrological condition, water flow; modes and selection for decontamination equipment as well as arrangement, etc. of water catchments, to be determined by technical economy comparison of multiply schemes.
1.0.5 Contents not stipulated in this code may refer to other relevant regulations.
2 General requirements
2.1 Waterflow characteristic
2.1.1 Arrangement of flow duct shall be with favorable waterflow pattern to make the waterflow in suction bay straight, stable and even, the specific technical requirements are as follows:
1 Suction pipe arranged perpendicularly or horizontally shall be with waterflow approaching absorption hydraucone even in width and depth directions.
2 For Surplus kinetic energy being carried by waterflow because of elevation change, it shall be made a clean sweep before ultimately entering into water pump blast hole.
3 Suction bays shall be without waterflow conditions such as efflux, flow separation, high-velocity flow, eddy flow, free lower fluid and severe water table fluctuation, etc. Wave height of the water surface should not exceed 0.3m.
2.1.2 Mean flow rate in the fore bay should be less than 0.6 m/s; mean flow rate near the absorption hydraucone shall not be larger than 0.3 m/s.
2.2 Geometrical characteristic
2.1.1 Overflowing components in flow duct shall be designed to approximate to streamline and it should not with the following undesirable geometrical characteristics:
1 Control orifice and regulating gate of small size
2 Mutation of water flow direction
3 Proliferation transition of the waterflow
4 Scarps
5 Any asymmetric distribution design resulting in waterflow entering into suction bay
2.2.2 Regions with circumfluence or backwater shall be added with backfilling or be set with guide wall
2.2.3 Absorption hydraucone must be with adequate submergence depth to avoid inlet air caused by swirling, and thus to invoke unstableness of pump performance, vibration and cavitation erosion.
2.2.4 Absorption hydraucone and soleplate shall be with proper clear distance; suction pipe and tank wall shall be with proper spacing.
2.2.5 Backwall to upstream impediment or abrupt change section of overflowing cross-section of the water pump blast hole shall be with adequate length.
2.2.6 Joint forms of source of cooling water and influent fore bay are: open type, headrace type and aqueduct type, etc. technical requirements for arrangement of several common used flow ducts see appendix A.
3 Flow duct
