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Application of Conical Springs in Large Float Glass Melting Furnace Kiln

Abstract

The use of conical springs on glass furnace components was proposed by the European company DTEC in the early 21st century. Applying conical springs between the steel columns on both sides of the melting section ensures uniform pre-tensioning of the large refractory when in a cold state. During expansion in a hot state, the springs can freely extend within a certain range. This not only ensures convenient temperature control during heating but also significantly reduces labor intensity. It eliminates the uneven tension of the large refractory caused by the previous experience-based adjustment of tension rods.

The application of conical springs in domestic glass furnaces is limited, and the adjustment of springs during the kiln process is still in the exploratory stage. Based on digestion and absorption, a certain domestic company applied conical springs to its contracted 800t/d melting furnace project in Africa. The project furnace consists of 7 small stoves, and the melting section has 13 large refractories. Each large refractory uses 4 conical springs on both sides (a total of 52). After the construction of the large refractories is completed, during the demolding of the large refractories, the top is raised by 10mm, and both ends of the refractory shrink inward by 20mm simultaneously. At this time, the span (B) of the refractory is 12900mm, considering only the weight of the large refractory itself (without insulation layer). The horizontal thrust calculation is as follows:

  1. Actual Measurement and Adjustment

To ensure uniform pre-tensioning of the large refractory in a cold state, adjustments can be made by measuring the H-cold value of each section of the large refractory conical springs. The specific adjustments are as follows:

(1) After assembling the springs, pre-tighten the M72 nut in a free state, the top iron end contacts the refractory foot iron, and make corresponding marks on the screw. The 80-pin shaft is 350mm away from the top iron end.

(2) For safety operations, temporarily lift the refractory by 8-10mm in two steps to lift it off the refractory mold. When starting to lift the refractory, first adjust the safety top wire in the conical spring assembly to top the refractory foot iron. When the safety top wire cannot be adjusted, adjust the conical spring nut. In this way, each time the nut is tightened by two notches, the top wire follows and tops once. Operate symmetrically on both sides, measure the refractory height once for each tightening, and when the refractory height reaches 5mm, adjust the next section of the refractory. Adjust in this way from back to front once, and then adjust for the second time.

(3) When the large refractory arches by 8-10mm, tighten the M72 nut in place, and then make a fine adjustment to the pre-tension force based on the measured H-cold value. When adjusting, refer to the unified adjustment of the arch height of the front and rear large refractories.

(4) After adjustment, all safety top wires in the conical spring assembly should be tightly tensioned. At this time, the spring is in the second position, compensating for the elastic deformation of the refractory beam. See Table 1 for measured data.

Through the cold-state calculation of conical springs, the pitch of the M72 nut is 6mm. When lifting the refractory, the M72 nut needs to be tightened for 8 turns. The actual measured cold-state values and the theoretically calculated cold-state adjustment values are basically consistent, both within the expected range. This not only meets the requirement of uniform pre-tensioning of large refractories but also provides reference experience for the heating adjustment in the hot kiln.

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