Pivotal role of Air/Gas ratio for Efficient running of Gas Burners
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A few questions raised in this subject:?
1.???? Are the Gas burners giving right AIR + GAS MIXTUTRE??
2.???? If Burner is fitted External Air Blower, how do we can ensure that right amount of AIR for both LNG/PNG burning and LPG burning??
There are various methods of Air/Gas ratio control:?
(a)Cross-Connected Ratio Regulators?
·???????? Composed of the following components:
a.????? Air Control Device (Control Valve or VFD)
b.????? Proportionator/Ratio Regulator
c.?????? Limiting Orifice
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·???????? Control signal sent to the air control device, and an impulse line from air manifold feeds the fuel’s ratio regulator to adjust the fuel flow.
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CROSS CONNECTED REGULATOR FOR NOZZLE-MIX BURNERS:
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When used with nozzle-mix burners, the vent of a 7218 Regulator is cross-connected to the main air-line downstream of the control valve. Regulator outlet pressure then equals air impulse pressure, and gas flow remains proportional to air flow at all firing rates.
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In mostly Italian Burners, ‘Cross-connected AIR/GAS Ratio regulator’ can be seen:
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In Eclipse RatioAir Burners we can see ‘Cross connected Air Gas Ratio regulator’
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(b)????????????? ?Mechanically-Linked Control Valves
Air Valve and Fuel Valve connected via mechanical linkage.
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?In mechanically controlled type, if air and gas both have been individually controlled then it leads to under burning or over burning of the gas which is not an efficient way of gas combustion.
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In following burner, AIR DUCT’S control damper is fixed type. So with the fixed type Damper we cannot do FINE ADJUSTMEMT OF AIR SUPPLY VOLUME to maintain a ‘Stoichiometric Air+Gas mixture. This AIR DAMPER does not have any ‘FINE CONTROL ADJUSTMENT’ like ‘GRADIENT MANUAL CONTROL BUTTERFLY VALVE’ is having.
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?If any kind of ‘Gradient manual control’ system can be put in the PIVOT of Air damper, so that with the GRADIENT CONTROL we can adjust the adequate Air volume to reach the mixing cone. This will help us to prevent the situation of either ‘under supply of Air’ or ‘over supply of Air’. Both ‘under supply of Air’ or ‘over supply of Air’ can create ‘INCOMPLETE COMBUSTION’ of Gas (PNG/LNG or LPG) and subsequently more yellowish/reddish flame can appear.
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(c)Electronically-Linked Control Valves:
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·??????? System’s control interface receives single control signal, and controls multiple actuators (can control up to 4).
·??????? Increased Complexity and Cost with Additional Components.
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Summary:
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a.????? For proper flame setting – can we make some kind of arrangement for
AIR SETTING(FINE TUNING OF AIR FLOW) same as we do in MULTIBLOC for GAS FLOW SETTING?
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b.???? In most of the Italian burners we can see they use “CROSS CONNECTED RATIO AIR/GAS REGULATOR”. Those burners are quite fuel efficient as they have more scope of flame setting -> they have both
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GAS SETTING FINE CONTROL
AIR SETTING FINE CONTROL
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c.????? For example even in Oxy Acetylene-gas welding, we normally adjust both Acetylene flow and Oxygen flow for proper flame tuning.
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?????? Please see the attached video:
??????? REF: Oxy Acetylene-gas welding-FLAME SETTING ADJUSTMENT.mp4?
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d.???? Please see the video of Maxon Textle industry burner where final flame is running with BLUE COLOUR.
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REF: Maxon Ovenpack for the Textile Industry.mp4?
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“Main motto should be to get BLUE FLAME in a Gas Burner, burner should be a GREEN ONE.”?
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Senior Service Manager – India, Bangladesh and Indonesia Operations
2 个月Optimizing Air-to-Fuel Ratio There is a balance between losing energy from using too much air and wasting energy from running too richly in any combustion process. The best combustion efficiency occurs at the optimum air-to-fuel ratio, and controlling this provides the highest efficiency. A liquid and gas fuel burner achieve this desired balance in most scenarios by operating at 105% to 120% of the optimal theoretical air. For natural gas-fired burners,?the stoichiometric air required is 9.4-11 ft.3 / 1.0 ft.3 of natural gas or approximately an air-to-gas ratio of approximately 10:1. In this case, there is an excess oxygen level of 2%. In the combustion zone, it is challenging to measure excess air. However, in the stack, it can be easily measured using Oxygen analyzers. Operating with 5%-20% excess air would correspond to a 1% to 3% oxygen measurement in the stack. The ideal air-to-fuel relationship will vary at different operating loads. Tuning is the act of establishing the desired air-to-fuel relationship under various operating conditions. It can be accomplished when evaluating specifics in the stack: temperature, oxygen concentration, carbon monoxide, and NOx emissions.