Applications And Features; Structure And Mode Of Operation - Honeywell HON 985B Operating And Maintenance Instructions Manual

1.3

Applications and features

• Applications
– Variable mixing of air and fuel gas for gas engines (e.g. for λ-control, electronic spark control,
combustion-chamber temperature control)
– Mixing gases for operating gas motors with multiple types of fuel gas (e.g. sewage gas,
secondary operation with natural gas)
– In general, mixing all sorts of gases (e.g. boosting low calorific-value gases like waste dump gas)
– Applicable for natural gas, sewage gas, dump gas, mine gas, propane, butane and neutral gases
• Features
– Simple construction
–
– Adjustable fuel-gas mixing gap provides for flexible mixing ratios
– Fine adjustment of mixing ratios possible
– Sensitive stepper motors provide for precise adjustment of mixing gap
– Turbulent mixing (homogenization)
1.4

Structure and mode of operation

gas 2 (fuel gas) flowing in through an upstream gas pressure control section to the same pressure as gas 1 (air). With the
reduction of the cross-section, there is an acceleration of gas 1 (air) flowing in. Acceleration means the pressure of the gas
The downstream flow edges of the torpedo support the turbulent mixing of the two types of gases (homogenization).
For a more precise adjustment of the mixing ratio λ-control, for instance), there are sensitive electronic control loops
and motors that can adjust the gap according to operational requirements.
Mixture of air / fuel gas
not rich enough
increase mixing gap
HON 985B - 140/65-ZW-N-NI
Constriction
device
(torpedo)
Gas 1
(Air)
Venturi
nozzle
Adjustable
mixing gap
Mixing zone
Fig 1: Functional principle
985.29-1 p.04
too rich
reduce mixing gap
Gas 2
(Fuel gas)
Stepper motor
with control*
Air / fuel
gas mixture
*) Stepper motor control, e.g. for
– λ-control
– Control of cylinder temperature
– Electronic spark control