Fiberglass Spinner

Introduction

Fiberglass SpinnerIn the manufacturing of Glass-Fiber wool for insulation a melt of a material such as glass is inductively heated at a stage intermediate an initial liquefying stage and a refining stage. Induction heating is the process of heating an electrically conducting object (usually a metal) by electromagnetic induction, where eddy currents are generated within the metal and resistance leads to Joule heating of the metal. An induction heater (for any process) consists of an electromagnet, through which a high-frequency Alternating current (AC) is passed. Heat may also be generated by magnetic hysteresis losses in materials that have significant relative permeability. The frequency of AC used depends on the object size, material type, coupling (between the work coil and the object to be heated) and the penetration depth.

The function of the intermediate induction heating stage is essentially limited to raising the temperature of the melt a relatively minor amount to a refining temperature. Therefore, the induction heating stage may be compact with an intensified heating rate and rapid throughput, thereby permitting the induction heating zone to be a "cold" walled vessel without an appreciable effect on efficiency.

A stream of molten glass is dropped into a spinning cup that has numerous holes in its wall. Glass fibers extrude through the holes under centrifugal force and meet a high-velocity air blast that breaks them into short lengths. On their descent to a traveling belt below, the fibers are bonded together with an adhesive spray. The binder is cured, and the wool is gently packed into chopped batts or rolls.

Process

Fiberglass Spinner ProcessThe molten glass will harden and collect in the spinner cup if allowed to cool. The spinner cup temperature must be controlled to maintain fiber quality and a functional spinner mechanism. The GD402 / GD40 gas density analyzer is used for control of the spinner cup temperature. By measuring the Specific Gravity (S.G) of the Natural Gas (N.G.) air mixture used for fuel gas, the BTU (heat) value of the fuel can be determined. The BTU value of the N.G. will change as air is mixed with it. The output of the GD402 can be fed to a control loop configured to hold an optimal fuel gas S.G.

There are usually multiple applications in each fiberglass-manufacturing site. The historic measurement technology is Gravometric or thermal conductivity. There are limitations in performance, supply and cost of ownership of each one. Calibration time, thermal stability, parts availability are the three most immediate issues faced by owners of thermal conductivity or Gravometric technologies.

* A table similar to the one below for Propane / Air mixture is used for control purposes

Propane / Air Mixture
                    % LPG % Air SGU BTU/cuft
    47.54 52.46 1.252 1196
  50.87 49.13 1.27 1280
  54.24 45.76 1.287 1365
  57.65 42.35 1.306 1450
  61.11 38.89 1.324 1538
  64.62 35.38 1.342 1626
  68.16 31.84 1.361 1715
  71.76 28.24 1.38 1805
  75.4 24.6 1.4 1897
    46.62 53.38 1.247 1173
  49.88 50.12 1.264 1254
  53.18 46.82 1.282 1338
  56.52 43.48 1.3 1422
  59.9 40.1 1.317 1507
  63.33 36.67 1.336 1593
  66.8 33.2 1.354 1681
  70.32 29.68 1.373 1769
  73.88 26.12 1.392 1859
    45.76 54.24 1.243 1151
  48.95 51.05 1.259 1232
  52.18 47.82 1.276 1313
  55.45 44.55 1.294 1395
  58.76 41.24 1.311 1478
  62.12 37.88 1.329 1563
  65.51 34.49 1.347 1648
  68.95 31.05 1.365 1735
  72.43 27.57 1.384 1822
    44.93 55.07 1.238 1130
  48.06 51.94 1.255 1209
  51.23 48.77 1.272 1289
  54.43 45.57 1.288 1369
  57.68 42.32 1.306 1451
  60.97 39.03 1.323 1534
  64.29 35.71 1.341 1618
  67.66 32.34 1.359 1702
  71.07 28.93 1.377 1788
    44.15 55.85 1.234 1111
  47.22 52.78 1.25 1188
  50.32 49.68 1.267 1266
  53.47 46.53 1.283 1345
  56.65 43.35 1.3 1425
  59.87 40.13 1.317 1506
  63.13 36.87 1.335 1588
  66.44 33.56 1.352 1672
  69.78 30.22 1.37 1756
    43.41 56.59 1.23 1092
  46.42 53.58 1.246 1168
  49.47 50.53 1.262 1245
  52.55 47.45 1.262 1322
  55.68 44.32 1.295 1401
  58.84 41.16 1.312 1480
  62.04 37.96 1.329 1561
  65.27 34.73 1.346 1642
  68.55 31.45 1.363 1725

Product Recommendations

Analyzer: GD402 Gas Density Meter
Sensor: GD40 Gas Density Detector

For more information contact you local Yokogawa Analytical Marketing Department.

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