Reduced fuel costs in process furnaces and dryers


Renewal of hot air.

Many manufacturing processes must use hot air dryers to evaporate the solvents of coatings, laminates and finishes.

Displacement and heating of large amounts of air, involve high costs.
Most think that the first option to control costs is to reduce the fresh air, to the point where complete drying, the desired production rate is ensured. However, this reduction of air can cause fire or explosion due to a dangerous accumulation of flammable vapors produced by insufficient air renewal.

As the cost of fuel increases, so do concerns about safety and energy optimization.

 

Control of flammable vapors gas analyzer

Security technology furnaces and dryers for processes that are released and evaporate relatively quickly, solvents and other flammable substances is governed in Europe by the standard UNE-EN 1539: 2015: Dryers and ovens in which flammable substances are released. Safety requirements having equivalent NFPA 86 standard EE. UU.

Section 11.6.8.1 of the American standard states: “… the rate of air renewal security must be designed and maintained during operation to avoid vapor concentration in the oven, without exceeding 25% LFL (Limits Flash) provided there is no active surveillance of the FLF.

NFPA 86 also allows a substantial reduction in the renewal rate of air in cases where “there is a constant concentration indicator solvent vapors and the controller is provided ….”

When these devices are installed to continuously analyze the gases from the drying zone, the vapor concentration in that area may be higher, provided they do not exceed 50% LEL. In addition to an increase in security, it enables cost reduction, by specifying heat a smaller volume of fresh air.

Active safety monitoring can be performed by thermal flame analysis (FTA) in the oven chamber, where the current limit concentration is monitored. Accordingly, air blowers and clean exhaust gas and the heating furnace can be regulated automatically increasing process safety.

 

Prevex gas analyzer for measuring the solvent vapors and other flammable substances.

Some features of the analyzer Prevex:

  • Reliable and accurate measure of flammability (explosiveness; % LEL ) of the gas sample, enabling its use in security applications in process
  • Direct measurement of flammability without applying correlation factors other gases
  • As in situ , in conduit without sample transport. Cold spots are avoided and gains in response time.
  • Sensor very quick response : <1s.
  • Due to its universal calibration it is very sensitive to variations in the composition of the gas matrix to analyze unlike other technologies such as catalytic sensors, FID, etc.

This allows savings at different points:

  • An adjustment in the air renewal without affecting production levels or affect the safety requirements.
  • An increase in the production rate without increasing costs or existing fuel air
  • Recirculation of hot exhaust gases back to the drying zone
  • Reduction rates furnace to decrease the fuel required for efficient operation of the thermal oxidizer.
  • Gas reduction furnace outlet to reduce the fuel required for an efficient process

The benefits can range from simply reducing air exchange and / or an increase in production. This results in significant fuel savings.

Some advantages of using analyzers can go unnoticed. An analyzer that reduces the air renewal in the drying zone, can also reduce the cost of emissions.

Also in some cases it could use a thermal oxidizer smaller capacity, or add additional production lines to existing incinerator. In many cases, the cost is amortized Prevex analyzer quickly.