Excessive dilution water is added to the vacuum broke chest. Especially when the chest only processes paper trims, check the spray water control and water pressure. Overflow from the wire pit flows into the vacuum broke chest. Adjust the overflow of the wire pit to prevent excessive dilution water from entering the broke handling system. The vacuum broke chest has insufficient capacity to process wet broke. Modify the dispersing equipment to meet the dispersion requirements for full-width broke. Inspect all pumps and control systems equipped for the broke handling system. Verify whether the pump capacity can meet high flow demands, and check the length of the pump suction line. Check the control configuration of the vacuum broke chest. Broke floats in the pulper. The pulper shall submerge the broke and defiber it promptly. Adjust the position of the spray pipe. Check the circulation system. Ensure sufficient agitation to draw the broke into the rotor area. Liquid level fluctuation occurs in the broke pulper.

Causes of forming fabric arching White water continuously flows to a single point on the inner side of the forming fabric. Remove accumulated fibers and take proper measures to eliminate factors causing white water tray overflow. Pulp deposits on breast roll, press roll and turn roll, which are formed as water flows around the rolls. Check the alignment of breast roll, couch roll and turn roll through the seam line and running track of the forming fabric. Remove burrs on all rolls including table rolls. Clean the holes of the couch roll before installing the forming fabric. Replace worn dewatering elements and turn rolls. Adjust the tension of the forming fabric with tension rolls and stabilize tension fluctuation. Consider installing spreader rolls on the fabric return path. Repair or replace worn and deformed vacuum boxes. Reduce vacuum degree to avoid suction and dragging of the forming fabric. Internal arching is mainly caused by pulp deposits on internal breast rolls, turn rolls, couch rolls an

The main spare parts of the dryer section are dry fabrics and felt ropes. Damage and premature removal of dry fabrics are mostly caused by external and operational factors. Common faults include holes, edge cracking, local creasing, fabric wandering, and squeeze breakage. Except for unexpected and unavoidable failures, most of these problems can be prevented by careful and standardized operation.

Adaptability of Hydraulic Headboxes Hydraulic headboxes were developed alongside high-speed twin-wire paper machines. Owing to the short forming surface of twin-wire formers — in other words, the extremely short forming time of the paper web — the web is essentially "set" once the stock jet impinges on the wire. Therefore, the stock must be uniformly distributed within the headbox. High-efficiency, compact, laterally uniform single-inlet tapered headers and fixed homogenizing devices are commonly adopted. High-velocity stock flow generates intense micro-turbulence through cross-sectional or geometric changes of fixed elements, dispersing the stock suspension. With stable longitudinal flow and no cross currents inside a hydraulic headbox, the basis weight profile of the sheet can be adjusted by regulating the stock concentration of the header tubes, achieving better results than locally modifying the lip opening with 微调 rods. This is an advantage unattainable by roll-type headboxes. The jet velocity of a hydra