Economizer problem

Economizers can be divided into boiling and non-boiling economizers according to their relationship with the furnace body. Generally, the boiling economizer is suitable for medium and high pressure boilers. It is integrated with the boiler and is also called inseparable. Its characteristic is that there is no valve between the economizer outlet and the boiler. When the boiler is running, 10% to 20% of steam will be generated while the feed water temperature rises. Non-boiling economizer is suitable for low-pressure industrial boilers, and there is a valve control between the economizer and the boiler. The feed water temperature at the outlet of the economizer is 40-50°C lower than the saturation temperature of the boiler water in the drum, so the feed water will not boil to generate steam. There are certain requirements for the water flow speed in the economizer. The water flow speed cannot be very high to avoid excessive flow resistance and increased flow loss. However, the water speed of non-boiling economizer should not be less than 0.3m/s ； The water speed in the boiling economizer should not be less than 1m/s. This is because the solubility of gas in the water will decrease when the feed water is heated, so the oxygen that has not been deoxidized or not removed from the feed water will precipitate. There must be a fast enough flow of water to take away the oxygen, otherwise the oxygen will attach to the inner wall of the pipe and corrode the pipe wall. Especially in boiling steel pipe economizers, in order to avoid steam-water stratification caused by steam staying on the pipe wall, deteriorating heat transfer and causing overheating of the pipe wall, a higher water flow rate is required to take away the steam. Therefore, the water speed requirement of boiling economizer is higher. When designing and installing a non-boiling economizer, the following safety technical requirements should be met: 1. When installing a non-boiling economizer, a bypass flue must be provided. In this way, when the boiler is ignited. The flue gas can be discharged into the chimney from the bypass flue to prevent the economizer from generating steam. ； When the boiler is running, if you want to inspect the economizer, you can also allow the flue gas to be discharged into the chimney through the bypass flue. If there is no bypass flue, the economizer outlet should be connected to the water tank when the boiler is ignited. 2. When installing an economizer, a thermometer should be installed at the inlet and outlet of the economizer. ； A pressure gauge is advertised at the entrance ； Install a safety valve at the outlet ； An air valve should also be installed at the highest point of the outlet: To remove accumulated steam and air in the economizer ； A drain valve should also be installed at the lowest point of the economizer inlet. In order to drain the accumulated water in the economizer during maintenance ； In addition, a straight-through water supply pipeline should be equipped so that the water supply can directly enter the boiler to avoid affecting the boiler water supply when the economizer fails. 3. The surface of the economizer is prone to dust accumulation. During the operation of the boiler, in addition to blowing soot once per shift to improve heat transfer efficiency, when designing and installing the economizer, the flue gas flow rate should not be less than 4 to 5 m/s at rated load, but it should not be greater than 7 to 13 m/s to avoid serious wear and tear. 4. The non-boiling economizer must strictly control the outlet water temperature to ensure that the feed water is 40°C to 50°C lower than the boiler water saturation temperature to avoid steam generation and water impact accidents.

Simple, large boiler* * It is stipulated that a thermal deaerator should be equipped. The temperature of the deaerated water is basically 104 degrees. The impact force is large and ordinary cast iron economizers cannot withstand it.