External heat removal load
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What are the adverse effects of prolonged overloading operation for external heat extraction? Please give me some advice.
Our external heat exchanger has been operating under overload for over half a year now, and no problems have been observed; the main thing is to improve waste discharge management and keep the alkalinity at acceptable levels. Strengthen communication and keep the inlet water temperature from dropping too low.
As long as the external heat exchanger does not experience overheating or overpressure during operation, chemical dosing and sludge removal are carried out continuously, the incoming water is free of aerobic bacteria, and the pH level and phosphate content of the boiler water are properly controlled, there will be no problems. A higher load is also acceptable; it will only result in a lower temperature of the superheated steam from the waste heat boiler.
For example, if 75 tons of steam should be sent normally, but 95 tons are actually sent, will that have no impact on the equipment?
Can it be without it? Can the steam quality be good? With a fixed area design, unless the heating capacity is increased, an increase in feedwater will result in insufficient heat absorption; when steam is generated at the same pressure, there will be significant water content in it, unless steam with a lower pressure and lower temperature – i.e., saturated steam at reduced conditions – is produced. . . What’s the point of having unsaturated vapor at the same pressure? It’s possible that the external heat exchanger’s superheater tubes could be damaged due to the two-phase gas-liquid flow. . . :lol
When external heat extraction operates under overload for extended periods, it is common for leaks to occur in the water supply pipes and steam output pipelines. External heat extraction typically generates steam at 3.5 MPa, which is at a high pressure; once a leak occurs, it is not easy to seal it up.
Excessive external heat load is definitely harmful to the equipment; it may not be apparent in the short term, but it will become evident over time.
Long-term overloading of the external heat extraction system certainly has negative effects. For example, an excessive amount of steam makes it difficult to ensure its quality; it increases the load on the rear superheating system, leads to more leaks that are hard to deal with, and raises the likelihood of safety valves activating. This especially affects the lifespan of the external heat extraction system, which under normal conditions can last five to six years, depending on specific circumstances. Long-term overloading undoubtedly increases the risk of pipe ruptures. In our plant, the external heat extraction system is operated at nearly double its designed capacity for a long time, and reducing the amount of slag added isn’t allowed either – it’s truly frightening, and we’ve already suffered many consequences as a result.
The external heat exchanger installed in my unit far exceeds the designed load, resulting in a decrease in steam quality. Severe salt deposition occurs in the turbine, preventing it from reaching higher speeds, and the safety valves operate frequently. As a result, most of the steam-water separation centrifuges inside the drum were damaged; last year, during maintenance, an external heat exchanger with a higher capacity and a new drum were installed. Moreover, strict safety requirements apply: overheating, overpressure, and overload are strictly prohibited. These issues may not be apparent in the short term, but once an accident occurs, it can have serious consequences; this cannot be taken lightly!
What do you mean by suffering? Could you be more specific? What troubles are there?