【JST-024】One-on-one consultation office for boiler technology experts

This post was last edited by lizhenpeng on 2012-4-5 08:23. May I ask the original poster if there are any good solutions to reduce heat loss during the startup of back-pressure units (referring mainly to back-pressure exhaust steam). (Moderator’s note: Refer to answer on floor 5 for guidance.)

This post was last edited by lizhenpeng on 2012-4-5 08:23. I would like to ask how the pressure and temperature for arranged and connected pipes are determined, as well as how the pressure and temperature for arranged and connected drainage expansion devices are determined. Thank you. (Forum moderator’s note: Refer to answer on floor 6.)

I would like to know about the operation of reverse osmosis for desalinating water; it would be helpful to have pictures from the site

This post was last edited by gjn1970 on 2012-4-4 at 22:37. The regulations for backpressure units specify that they should be operated in a drained state during startup, but it is also necessary to determine the appropriate startup method based on the cylinder temperature – whether it is a cold-start, warm-start, or hot-start. Where thermal stress permits, the startup time of the unit can be reduced; for example, in the case of medium-parameter backpressure units undergoing a hot-start, when the cylinder temperature is above 350 degrees, the unit can be quickly brought up to speed after friction checks are successful, passed beyond the critical speed, adjusted to a constant speed, and connected to the power grid or heat network under load. It is important to note that the no-load operation time should not be too long, in order to avoid cooling of the steam control stages at low loads, as well as to prevent the exhaust temperature from rising too high due to the heat generated by frictional ventilation. To ensure safety, it is not recommended to recycle the exhaust gas from the backpressure machine. Firstly, backpressure machines are usually operated at a basic load (as only in this way can they operate economically), and they are started very rarely throughout the year; additionally, this is done to reduce thermal shock.

The fluid flowing in the regular drain and continuous drain pipes is saturated water at the pressure of the drum (the head pressure due to the difference in level between the drum and the water wall headers can be ignored). Therefore, the pressure and temperature in these pipes are designed based on the pressure and corresponding temperature of the saturated water in the drum. In addition to regular wastewater discharge, the regular drain also handles wastewater discharged during boiler accidents (with the discharge point located in the drum), as well as wastewater from the bottom of the continuous drain system. The pressure and temperature of the continuous blowdown expansion vessel depend on its operating pressure, which is generally 0.6 MPa. This is because the appropriate destination for the secondary steam at the top of the continuous blowdown expansion vessel is the deaerator; the pressure in the high-pressure deaerator in power plants is also 0.6 MPa (if it is connected directly to an atmospheric deaerator, there is usually a pressure control valve at its outlet). In a regular blowdown expansion vessel, since the secondary steam is discharged directly, its operating pressure is higher than atmospheric pressure; in addition, there is also a U-shaped water seal at the bottom outlet, so its operating pressure is approximately 0.1 MPa.

Sorry, this is outside my area of expertise; please search on the forum

This post was last edited by lizhenpeng on 2012-4-6 08:26. Hello, I would like to ask how to calculate the coal consumption using an impeller-type coal feeder. (Moderator’s note: Refer to answer on floor 11 for guidance.)

This post was last edited by salesment on 2012-4-6 09:16. Hello! I would like to ask: What effects will introducing acidic gas into a boiler have on its operation? (Publisher’s note: Refer to answer on floor 10 for reference.)

When adding acidic gases, whether to utilize waste heat or carry out direct combustion is a consideration; the main issues associated with adding such gases are corrosion of the low-temperature heating surfaces and flues, as well as increased costs for equipment inspection and maintenance. An economic and technical analysis is necessary, otherwise it will not be worthwhile.

This post was last edited by gjn1970 on 2012-4-5 at 16:10. The impeller coal feeder is a vital main equipment in the coal transportation system of thermal power plants. The impeller coal feeder is located below the slit-type coal unloading chute, mounted on the belt conveyor, and enables forward and backward movement as well as adjustable dosage to continuously feed raw coal onto the belt conveyor and send it to the raw coal bin. Features: It adopts a separate driving system for the coal-feeding mechanism and the crane mechanism, offering a rational and simple structure that is easy to maintain and reliable in operation ； The coal feeding mechanism uses electromagnetic speed control and motor-driven speed control, making it easy to operate ； The coal feeding mechanism is equipped with a reliable mechanical safety friction clutch that can automatically cut off the power supply ； The impeller features a modular structure ； All four driving wheels of the traveling mechanism are drive wheels, ensuring reliable operation and good synchronization ； This machine is available in two installation configurations: left-mounted and right-mounted. The vane-type coal feeder itself is unable to perform weight measurement in real time; however, weight measurement for the coal fed into a single furnace, as well as the total amount of coal used by multiple furnaces, can be achieved using an electronic weighing coal feeder (located in front of the furnace) or a nuclear scale installed above the coal conveyor belt (located in front of the coal hopper).