Boiler house Heat recovery systems
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Pump The pump should be situated in a vertical pipe pumping upwards as shown in Figure 5. This position ensures that the pump shaft is horizontal which reduces the thrust bearing load and ensures positive air purging from both the rotor chamber and impeller housing. Where pumps can only be installed in horizontal pipework, it is imperative that the pump shaft is horizontal, or slightly higher at the vent plug end. The shaft must not fall below the horizontal plane, even by a few degrees, as this causes premature wear of the top bearing and shaft. Pumps are not to be installed with the shaft in the vertical plane, as this may lead to dry running of the top bearing, noise and possible pump failure. Try to position the pump motor away from hot surfaces and allow access to the switch on the terminal box. Ensure that the pump is not stressed by the pipework and that the pipework is properly supported either side of the pump. If necessary use proprietary mounting brackets. Pipework downstream of the pump is to match the outlet connection of the pump including the isolating valve. Arrows on the pump base indicate the water flow direction through the pump. When connecting the pump to pipework, the gasket and union nut should be assembled dry: - It is not necessary to use any sealants. - Ensure that the gasket is positioned correctly and tighten the union nut firmly. Do not over tighten and take care not to displace or distort the gasket. - The pump should not be subjected to extremes of temperature. Do not attempt to start the pump until the system has been filled with water and both the pump and system have been vented. To avoid any possible sediment do not fit the pump in the lowest part of the system and position the take off point from the cold treated water storage tank above the base of the tank. - The return line should be below the lowest water level in the storage tank. - The minimum inlet pressure to avoid cavitation of the pump is equivalent to 2.5 m head of water. It is recommended therefore that the pump is installed at least 2.5 m below the lowest water level of the cold treated water storage tank as shown in Figure 5.
2.8 5
2.5 m (min.)
Fig. 5 Pump installation
Thermostat The HTS3 thermostat should be installed on the pipework leading from the flash vessel drain to the heat exchanger inlet, near to the heat exchanger, allowing easy access to the setting arrow. The base of the HTS3 should be held in good contact with the metal of the pipe removing insulation as required. The plastic covered spring fixing cable should be cut to an unstretched length slightly less than the circumference of the pipe and the hook and eyelet screwed into the ends. Stretch the cable round the pipe and position it in the groove across the front of the HTS3. Engage the hook and eyelet.
AI-P404-07 AB Issue 7
Page 5 of 8
Boiler Blowdown Heat Recovery Systems - Installation, Operation and Maintenance
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