The chemical production uses electric boilers, 2 sets of 12 tons of electrically heated steam boilers with a pressure of 35 kg.
Attention should be paid to the following issues when refitting electric boilers: The thermal deviation of each parallel heating pipe group should be minimized, and the system return water entering the electric boiler should be adjusted and distributed. For general low-temperature boilers, the flow rate is large, and the natural distribution method can be adopted, that is, the amount entering each parallel pipe group is naturally distributed according to the heating situation of each pipe group and the size of the pipeline resistance.
For high-temperature boilers, the relative amount of water is less, and the natural distribution mode should not be adopted, but the valve should be used to adjust the distribution, and the corresponding circulating water volume should be supplied according to the size of the heat load of the heating pipe group, so as to ensure that the water temperature of the outlet of each parallel circuit is not much different. At this time, the deviation of the water temperature at the outlet of each circuit can be controlled within 10 degrees Celsius.
A certain water flow velocity must be maintained in the heat tube of the modified electric boiler to ensure the cooling of the heat tube and prevent oxygen corrosion and the deposition of impurities in the water. For the downward heating pipe, it is necessary to maintain sufficient water velocity. After modification, the stagnation zone of water in the boiler should be minimized, especially at the end of the boiler, otherwise it is easy to cause oxygen corrosion, in order to be able to remove the gas precipitated in the water in time, the exhaust valve should be set at the high point of each circuit of the boiler. When two 12-ton electric heating steam boilers are converted to forced circulation boilers, measures should be provided to prevent sudden power failure and vaporization of boiler water caused by pump shutdown.