How to replace and install the headbox？

As the junction of the "conveyor" and "forming" of the paper machine, the basic task of the headbox is to provide good prerequisites for paper sheet forming, that is, to evenly distribute the pulp along the width of the paper machine, to ensure uniform pressure, speed, flow, concentration, and control ability and uniformity of fiber orientation; to effectively disperse the pulp fibers and prevent fiber flocculation.

Ⅰ Stop Paper Machine

The prerequisite for stopping the machine is that the suction transfer roll has been raised to the highest position and the spray water pipe for washing the wet paper web must be open. During the whole process, the short circulation system is flushed with water to keep the headbox clean. The pulp pipeline after the white water tank outside the machine is flushed to prevent the pressure screen from being blocked after stopping the machine.

The Shutdown Sequence

1) Stop the pulp supply pump;

2) Stop the supply of auxiliary materials (additives);

3) Let the white water recirculate for a few minutes to flush the dilution circulation system, short circulation system and headbox;

4) Stop the pulp pump;

5) Stop the pressure screen;

6) Stop the short circulation system;

7) Run the cleaning procedure of the dilution system;

8) Stop the dilution system.

Ⅱ Start up Paper Machine

Before starting up, check the following

1) Is there water in the short circulation system tank?

2) Is the sealing water of the pulp supply pump and pressure screen turned on?

3) Is the headbox cleaning spray pipe turned on?

4) Are all cleaning holes and inspection holes closed?

5) Is the upper lip plate in its normal operating position?

6) Is the lubrication spray pipe turned on?

7) Is the thermal compensation system turned on?

The Sequence of Stat-up

1) Open the forming section and check whether the lubrication spray pipe of the ceramic panel is open, and check the speed of the forming section;

2) Open the vacuum system of the forming section;

3) Open the dilution circulation system;

4) Open the short circulation system;

5) According to the running speed of the paper machine, adjust the pressure head and liquid level control of the headbox to the set value, and enter the automatic control state;

6) Open the pressure screen;

7) Open the pulp pump;

8) Check the headbox pressure;

9) Open the pulp supply pump.

Before the pulp supply pump is turned on, the pressure head of the headbox must be adapted to the running speed of the paper machine. If the pressure is low, the pulp will clog the headbox.

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