Heat recovery heat exchangers utilize waste heat from flue gas for district heating.
1, Mainstream technical solutions
1. Direct steam extraction heating (conventional solution)
Extract steam from the intermediate pressure cylinder of the steam turbine, enter the heat exchange station after temperature and pressure reduction, and heat the municipal circulating water.
Advantages: simple renovation, low investment, fast response; Suitable for scenarios where the distance between the incineration plant and the heating area is close (≤ 5km).
Case: Beijing Chaoyang Garbage Incineration Heating Project, with a maximum steam supply of 80t/h, covering 2.3 million square meters and approximately 23000 households.
2. Cascade utilization+heat pump (efficient solution)
Adopting a three-stage recovery system consisting of a turbine heat pump, lithium bromide unit, and plate heat exchanger to extract condensed water and low-grade waste heat.
Tianjin Dongli project: 400 ℃ steam driven turbine extracts waste heat from condensate water; 150-200 ℃ steam driven lithium bromide unit; The 90 ℃ steam is then heat exchanged through a heat exchanger, increasing the overall thermal efficiency to over 60%, covering 5 million square meters and approximately 40000 households.
3. Mobile heating (flexible solution)
For areas where the pipeline network is difficult to cover, mobile energy storage vehicles are used to recover waste heat, transport insulation, and release heat at the end.
Advantages: No need for long-distance pipeline network, low investment, fast deployment; Suitable for dispersed and temporary heating needs.
3, Key advantages
Environmental protection and carbon reduction: replacing coal-fired/gas-fired boilers, significantly reducing SO ₂, NO ₓ, and dust emissions; A single project can reduce CO ₂ emissions by thousands to tens of thousands of tons annually.
Energy Efficiency: The comprehensive energy efficiency of the incineration plant has been increased from 25% to over 60%, achieving a clean and efficient operation.
Economically feasible: reduce heating costs and stabilize power plant revenue; The Jinan project saves 3300 tons of standard coal and reduces CO ₂ 8600 tons annually.
Livelihood security: Expand clean heat sources, enhance the resilience and stability of regional heating.
4, Implementation points and challenges
1. Core conditions
Distance matching: The distance between the incineration plant and the heating area should be ≤ 10km to reduce pipeline investment and heat loss.
Load stability: The heating load is matched with the waste heat output of the incineration plant to avoid "big horses pulling small cars".
Pipeline connection: Construct/renovate the initial heating station, main pipeline network, and heat exchange station to achieve coupling with the municipal pipeline network.
2. Main challenges
High initial investment: The construction costs of pipeline networks, heat exchange stations, and heat pump systems are relatively high.
Cross departmental coordination: requires collaboration among multiple departments such as environmental sanitation, energy, municipal administration, and heating.
Seasonal fluctuations: There is a significant difference in load between the heating season and non heating season, requiring a corresponding peak shaving/energy storage plan.
development trend
Technological upgrade: Efficient heat pumps, phase change thermal storage, and intelligent regulation further enhance the utilization efficiency and stability of waste heat.
Mode expansion: From single heating to cross industry utilization in multiple scenarios such as industrial steam supply, refrigeration, and agricultural breeding.
Policy driven: Under the dual carbon target, many regions have included waste incineration heat for heating in their clean heating plans, providing subsidies and support.
