Characteristics and causes of downtime failures in paper machine production and operation

The paper machine production line is a large-scale continuous production line mainly composed of papermaking equipment, pulping equipment and processing equipment. The equipment has a long process flow, many systems and complex specifications and models. In the process, no matter which single machine/component is damaged or fails to function, it will cause a complete shutdown and bring economic losses to the enterprise. Therefore, equipment maintenance is the basis for ensuring the normal production of paper machines, and it is also one of the key points of equipment maintenance management. This article will answer your doubts from the common fault characteristics in the production and operation of paper machines.

When the equipment or system loses the specified function or reduces the efficiency for some reason during the use process, it is called equipment failure.

Classification of downtime failures in paper machine production and operation:

There are two main types of downtime failures of paper machines: production inherent failures and equipment failures.

(1) Characteristics and laws of productive inherent fault shutdown

This type of shutdown is mainly to ensure product quality and meet production process requirements, especially the production of high-grade cultural paper is more prominent, the main reasons for shutdown:

1. Cleaning work. After a certain period of use, the function of the wet-end water filtration and dehydration elements (or materials) declines, and the initial effect of dewatering and filtration cannot be achieved, and regular cleaning is required.

2. Replace the main process equipment, such as copper mesh and felt after reaching the service life, they need to be replaced regularly; the rubber press roller and stone roller are worn by the paper and the scraper, and the change of the middle and height of the roller surface will affect the quality of the product, and it also needs to be repaired regularly or replace.

(2) Characteristics and analysis of equipment failure shutdown

Due to the particularity and complexity of the paper machine production process, equipment failures have the following characteristics:

1. There are many equipment failure points, and equipment failure and shutdown often occur.

2. Some parts have a short service life, and the frequency of replacement of spare parts is high.

3. There is a large gap between the failure cycle and the maintenance time occupied, which is difficult to manage.

The main reasons for equipment failure are as follows:

1. Abrasion: Reason 1: Parts and equipment that have been in contact with copper mesh, felt or pulp and molding paper for a long time, such as pulp pump, pulper, desander, vacuum box panel, press roll, calender roll, etc.; The second reason is the parts that move relatively frequently between parts, such as scrapers, steam inlet heads, cylinders, vacuum couch rolls, vacuum pumps, etc.

2. Lubrication: Bearings are inseparable from mechanical rotation. Paper machines with rotating rollers have many types and numbers of rollers. There are hundreds of bearings of various types. Therefore, lubrication management is very important, especially those affected by water, high temperature, Under the influence of heavy load, lubricating oil (grease) is easy to lose, evaporate and age, which will destroy the lubrication effect, cause bearing damage and shaft head wear. Therefore, regular inspection of refueling is essential.

3. Fatigue: Heavy-duty and continuous operation machinery is prone to fatigue damage. On the paper machine, because some parts are restricted by the mechanical structure and operation principle, the design strength of the parts (such as the mesh vibration spring plate, the electromagnetic clutch suction cup, the coupling anti-overload pin, etc.) should not be too large to avoid damage. The solution is to take measures such as maintenance and technical transformation.

Paper mills should regularly inspect and maintain paper machine production line equipment according to the failure characteristics of paper machines and follow the failure rules of paper machines.