Waste Heat Steam Generator Heating Surface Segmentation
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Solution Overview
Problem
Conventional heat recovery steam generators face challenges in managing high exhaust gas temperatures, leading to excessive thermal loading and material limitations, particularly in gas and steam turbine systems, where the high gas turbine exhaust gas temperatures exceed the thermal resilience of pipe wall materials, and existing desuperheating methods are inefficient and risk thermal shock or increased emissions.
Innovation Solution
A heat recovery steam generator design with a heating surface installed upstream of the first superheater to pre-cool the exhaust gas, coupled with a cyclone separator on the secondary side to prevent water ingress, allows for controlled cooling and steam temperature regulation, reducing thermal stress on components and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional heat recovery steam generator is used with high-pressure superheater at the exhaust gas inlet, then steam generation efficiency is improved, but the pipe wall materials are exposed to temperatures exceeding their thermal resilience
Solution Approach 1:
The patent divides the heating surface into multiple sections: a first heating surface section (cooling section) positioned at the exhaust gas inlet to pre-cool the gas, and a second heating surface section (superheater section) positioned downstream to generate steam at controlled temperatures. This segmentation allows the hot exhaust gas to be progressively cooled while generating steam, preventing any single section from exceeding material temperature limits.
Solution Approach 2:
The first heating surface section acts as an intermediary element between the hot exhaust gas and the superheater section. It absorbs excess heat from the exhaust gas before the gas reaches the superheater, thereby mediating the temperature transfer and protecting the superheater materials from thermal overload.
2Ease of operation
If desuperheaters are used to control steam temperature, then temperature regulation is achieved, but water droplets may enter the steam turbine and thermal shock problems occur
Solution Approach 1:
The patent performs preliminary cooling of the exhaust gas in the first heating surface section before the steam generation process in the superheater. This pre-cooling action prevents the need for downstream desuperheaters that would require injecting water into the steam line, thereby eliminating the risk of water droplets entering the turbine and avoiding thermal shock to heated components.
3Ease of operation
If intermediate and final injection coolers are used for temperature control, then steam temperature is regulated, but system efficiency is reduced and injection rates are limited
Solution Approach 1:
The patent converts the harmful excess heat in the exhaust gas into a beneficial resource by using it to pre-heat the feed water in the first heating surface section. This approach transforms what would otherwise be wasted thermal energy into useful heat for steam generation, improving overall system efficiency while still achieving temperature control without injection coolers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively mitigates excessive thermal loading, reduces material stress, and enhances operational flexibility by allowing precise temperature control and efficient steam production, while minimizing the need for intermediate injection systems and reducing emissions.
Implementation Method 1
a heating surface (44) arranged between the exhaust gas inlet (12) and a first superheater (15) in the flow direction of the exhaust gas
Implementation Method 2
a separator (45) connected downstream of the heating surface (44) on the secondary side
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a waste heat steam generator (8) having a waste gas inlet (12), wherein a heating surface (44) is arranged between the waste gas inlet (12) and a first superheater (15) in the direction of flow of the exhaust gas. The invention also relates to a method for operating such a waste heat steam generator (8).