The 75T fluidized bed boiler cannot be brought under load

Boilers designed by different manufacturers vary, as do the designs regarding the fuel used, etc.

Is it due to a problem with the boiler itself?

This post was last edited by ssun*nhong on 2010-12-17 at 10:14. If it is a problem with the boiler itself: please provide more details regarding the heating surface area of the boiler, its corresponding weight, and whether it uses finned tubes； From the superheating section to the economizer section: the area of each section, the arrangement pattern (staggered or in line – this helps in calculating the resistance and determining whether the fan is suitable), as well as the feedwater temperature parameters ； Steam parameters ； There are also expert opinions that provide a detailed explanation. Parameters such as flue gas volume and temperature, as well as the flue gas exhaust temperature and its design value ；

Reply to 4# ssun*nhong: I’m sorry; I specialize in the recovery of waste heat from flue gases at the back of boilers, and I’m not able to provide detailed parameters regarding such technical issues. Sorry! !

This post was last edited by zgj2405 on 2010-12-18 at 16:46. Based on what you’ve said, since experts have already been consulted, they would at least take a look at your design documents first. Since the experts didn’t mention any issues with the heating surfaces, I think there shouldn’t be any major problems with the boiler itself. There are also parameters you might want to know for which no one can provide a fixed value. For example, the air pressure in the air chamber is determined by factors such as the specific gravity of the coal being burned (the properties of the coal), the air cap, the resistance of the air distribution plates, and the operating load of the boiler. After the boilers installed in various facilities are built, cold-state tests must be conducted before they are put into operation, in order to determine the air pressure values at different air flow rates and different layer thicknesses of coal, so that these values can be used as a reference during subsequent operations. Your question is hard to answer

This post was last edited by tjdxz on 2010-12-17 at 12:16. May I ask: where were your boilers manufactured?

Are many boilers like this? Some time ago, I visited a factory where their two 130-capacity boilers together could only handle a load of around 130, and the reason for this couldn’t be identified!

The boiler itself was manufactured by Harbin Boiler Factory; the fans were made in Xi’an. The installation work was carried out by a team from Jiangsu. Even now, we still rely on them to identify any problems – it’s been several years already. A cold-state test is also carried out before each circuit test; in our case, those tests are basically just for show, with the only requirement being that the fan is able to blow up the bedding. As for many of the things mentioned above, I really don’t know much about them. However, I can provide some data for reference: the water supply temperature is usually 60° if a high-temperature heater isn’t in use. The flow rate of the primary fan is generally around 150,000 m³/h with an operating setting of 100 (it’s not certain whether these numbers are accurate, as many instruments show incorrect readings). The flow rate of the secondary fan is around 20,000 m³/h with a setting of around 25. The air outlet of the sulfurization fan has been modified twice; the exact air flow rate isn’t indicated. There are eight measurement points for the bed temperature, but three of them are inaccurate, showing large discrepancies. The factory generally requires the bed temperature to remain below 950°. The bed pressure is usually maintained at 7,000 Pa; when the load is 40 T, it’s around 5,000 Pa when the load is 25 T. The oxygen level is kept between 8 and 13. On the left and right sides, there are A1A2B1B2 – in reality, there are only two coal scrapers. The temperature at the furnace exit is usually around 700°, whereas it’s often around 850° for another boiler in this plant. The negative pressure in the furnace chamber is generally maintained between -180 and -10. The accuracy of these parameters also needs to be verified. The temperature of the return conveyor can still reach around 800° these days; it used to be around 200°. In fact, all of this is just to illustrate how difficult it is to operate a 75T boiler, with no clear way to identify the problems. It gives the impression of being like a quack doctor; it’s more like hoping to win the lottery some time.

Haha, it’s not easy – so many people can’t figure out what’s going on with the diagnosis; it’s quite interesting. Usually, the designers at boiler factories are able to diagnose it.

This post was last edited by zgj2405 on 2010-12-18 at 16:46. A few days ago, I was on a business trip; there was a 75t/h boiler in another factory that also couldn’t handle any load recently. I thought the original poster was an old “friend”. It seems that the biggest problem with your boilers is likely related to inadequate attention to the installation details. Generally, for larger boilers, the boiler manufacturer sends professional commissioning personnel to carry out the setup, and basically offers free lifetime support and on-site service. I guess you didn’t carry out load acceptance tests; otherwise, you wouldn’t be in such a passive position now. Let me share my opinion for reference: \"At the boiling point on the right side, overheating occurs after boiling, and coking also takes place.\" ”This phenomenon indicates that the local fluidization condition is poor; possible reasons include uneven air distribution ； The coal fed into the furnace contains large particles ； The coal feeding deviation at the two furnace inlets may be excessive. The load-carrying capacity of CFB boilers relies to a large extent on ash circulation. What the poster mentioned – that the temperature at the furnace outlet is generally around 700, and it’s difficult to reach levels similar to those of another boiler in this plant, where it’s often around 850 – indicates that the temperature at the top of the furnace is insufficient; this phenomenon is likely caused by an inadequate efficiency of the cyclone separator. The optimal load for a 75-ton boiler should be around 60 t/h. A few days ago, I saw that boiler operating at this level as well, with a thermal efficiency of over 85%. Recently, the load couldn’t be increased due to an excess of fine coal powder, which reduced the efficiency of the separator. It is recommended to have a technician from the boiler manufacturer come for diagnosis and adjustment as soon as possible. Giving a small amount of money for debugging privately can also help companies save a lot of costs! Theoretically, the original poster can refer to it for learning*: http://bbs.hcbbs.com/viewthread.php?tid=24237