The core of the selection is to calculate the total gas consumption: add the carrier gas demand of each furnace (related to the furnace volume, furnace type and process), multiply it by the simultaneous use coefficient, and then consider peak demand such as furnace start-up and purge and future expansion margin. Then it was decided whether to use a single large-capacity furnace, multiple furnaces in parallel, or a dual-furnace system with one in use and one in standby, as well as supporting piping, pressure, and safety designs.
- Step 1: Calculate the carrier gas demand (m³/h) of each furnace
- Step 2: Multiply the simultaneous coefficient and superimpose the peak value (opening recovery, purging)
- Step 3: Reserve 10%–30% margin and room for expansion
- Step 4: Choose single, multiple parallel or double furnace redundancy
- Long-term operation at low load will reduce efficiency and avoid excessive amplification
Step 1: Count the gas consumption of each furnace
The carrier gas flow rate for each furnace depends on:
- Furnace type: integral-quench furnaces, mesh belt furnaces, and pusher furnaces have different ventilation requirements;
- Furnace volume: Often estimated by “air changes per hour”;
- Craftsmanship: Carburizing and heating before quenching have different requirements for atmosphere stability;
- Sealing condition: Furnaces with a lot of air leakage require greater flow to maintain positive pressure;
- Equipment manufacturer recommended value: Prioritize reference to the design flow rate of the furnace manufacturer.
It is recommended to make a list: furnace number, furnace type, design flow rate, actual operating flow rate, and work shift.
Step 2: Simultaneous coefficients and peak values
All furnaces will not use full gas at the same time, but there are peaks:
- The flow rate will temporarily increase during the recovery period after the integral-quench furnace opens the door;
- Furnace start-up and purge phases;
- Multiple furnaces are turned on at the same time.
Total demand ≈ Σ (steady-state flow rate of each furnace) × simultaneous coefficient + peak compensation. At the same time, the value of the coefficient should be combined with the production schedule, and should be on the high side for the sake of conservatism.
Step 3: Reserve a margin
It is generally recommended to leave a margin (e.g. 10%–30%) on top of the calculated value, taking into account future additions to the furnace. But the bigger the margin, the better: if the generator operates at a very low load for a long time, the efficiency and gas quality may decrease. Generators that support multiple gas production modes can be selected to adapt to load changes.
Step 4: Select a configuration plan
| Plan | Advantage | Things to note |
|---|---|---|
| Single large capacity | Concentrated investment and small area | During maintenance or failure, the entire line will shut down and a backup air source will be required. |
| Multiple units connected in parallel | Can start and stop according to load, good redundancy | Piping and controls are more complex |
| Double furnace body, one for use and one for backup | Maintenance does not interrupt the air supply and can be operated collaboratively | Suitable for continuous production and medium dosage |
| Each furnace is equipped with a small generator | Flexible and independent | Large number of equipment and scattered maintenance |
Example reference: Gos Control delivered a 40 m³/h double-furnace Endo generator to Zhejiang Jieneng Auto Parts to provide stable gas supply for 1–2 mesh belt furnaces; it configured 3 160 m³/h RX generators and a complete set of gas supply pipelines for 30 controllable atmosphere equipment of Zhejiang Qiujing Technology.
Don’t forget the matching design
- Air supply main pipe and branch pipe diameter and pressure loss;
- Flow meters and regulating valves at each furnace inlet;
- Prevent backfire, pressure relief and venting ignition;
- Condensate discharge;
- Interlock and alarm between generator and furnace.
Frequently asked questions
What happens if the generator capacity is insufficient?
The atmosphere flow in each furnace is insufficient, the furnace pressure decreases, air infiltrates, the carbon potential fluctuates and even oxidative decarburization occurs. The recovery time for the integral-quench furnace to open the door will also be extended.
Can I buy a smaller one first and then expand it later?
You can adopt a modular idea: install one unit first, reserve parallel interface and pipeline capacity, and add another unit when expanding production. This is more economical than one-time over-amplification.
What information is required for selection?
Furnace list and design flow rate, process type, shift, gas type and pressure, power conditions, site layout and future expansion plans.