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A LEAP forward: The HZI Low Excess Air Process

A LEAP forward: The HZI Low Excess Air Process

A LEAP forward: The HZI Low Excess Air Process

Product catalog summary
Introduction
Hitachi Zosen Inova's Low Excess Air Process (LEAP) is designed to enhance combustion efficiency while reducing operating costs and plant size. This innovative process optimizes the combustion process by using less air, which decreases the potential for corrosion and reduces the size of the boiler and flue gas treatment systems.
Process Fundamentals
  • Waste Lower Heating Value (LHV) above 9.5 MJ/kg
  • Flue gas recirculation
  • Cladding of boiler walls
  • Two-stage injection of secondary air (SA) and recirculated flue gas (RFG)
Typical Setup
The process involves two stages of injection to ensure complete combustion of primary gas from the grate:
  • Stage 1: Mixing and partial combustion with straight injection of RFG.
  • Stage 2: Full combustion with swirl injection of premixed SA and RFG.
Benefits
  • Maximized efficiency and minimized parasitic load
  • Reduced investment costs for new plants or increased power for retrofits
  • Improved control possibilities and uniform temperature and concentration profiles
Efficiency Gain Example
In a base case scenario of 1 line at 62 MWth, LEAP reduces O2 from 8 vol% to 4.5 vol%, increasing live steam by 1.5 MW and electricity production by 390 kW. Parasitic load for fans is reduced by 85 kW, and NH4OH usage for catalysts is reduced by 30%, resulting in estimated annual savings of €215,000 per line.
Corrosion Management
Despite concerns, LEAP maintains superheater inlet temperatures and reduces local concentrations of corrosive agents through intense two-stage mixing, significantly lowering the risk of corrosion.
Design Advantages
  • Staged combustion reduces local maximum temperatures
  • RFG promotes gradual oxidation and reduces uncontrolled NOx formation
  • Lower O2 content in SA/RFG mixture prevents high local temperatures
  • Enhanced control over combustion process and reduced flue gas flow rates by up to 20%
Conclusion
LEAP offers a significant advancement in combustion technology, providing efficiency gains, cost reductions, and improved environmental performance.
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Catalog excerpts

A LEAP forward: The HZI Low Excess Air Process-1

Hitachi Zosen A LEAP forward: The HZI Low Excess Air Process Highly efficient combustion with low O2 and low NOx

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A LEAP forward: The HZI Low Excess Air Process-2

LEAP: Maximized efficiency, minimized running costs, lower capital investment A LEAP forward: the HZI Low Excess Air Process LEAP: Maximized efficiency, minimized operating costs and a significant reduction of plant size – Hitachi Zosen Inova’s new process with low excess air kills three birds with one stone by optimizing the heart of your plant: the combustion process (patent pending). Using less air to combust the waste and at the same time reducing your plant’s corrosion potential sounds like a fair swindle? It isn’t. Our new process reduces the combustion air flow rate by 15–20 %, allowing...

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A LEAP forward: The HZI Low Excess Air Process-3

| The advantages of this design: • Staged combustion reduces local maximum temperatures • RFG mixes the primary combustion gas from the grate and causes gradual oxidation • The SA/RFG mixture in the 2nd stage avoids high local temperatures due to a lower O2 content than air alone • The staged combustion, the use of RFG and the lower O2 content all lead to a reduction of uncontrolled NOx formation • Higher degree of control possibilities: RFG in 1st stage to influence fire start by controlling radiation intensity, SA/RFG mixture in 2nd stage to maintain constant injection momentum over a wide...

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A LEAP forward: The HZI Low Excess Air Process-4

ITAD M ■ ■ A • ■ ■ ■ A + i 11 ♦ ♦ Hitachi Zosen LEAP: Maximized efficiency, minimized running costs, lower capital investment ^ ^ OVA Hitachi Zosen Inova AG | Hardturmstr. 127 | P.O. Box 680 | 8037 Zurich | Switzerland

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