The continuous cooking is a popular type of pulp cooking process just like batch cooking. Continuous cooking system can be divided into continuous digester and continuous tubular digester.
Advantages of continuous cooking
- For large-scale cooking equipment, the infrastructure investment and operation cost of continuous cooking equipment is relatively low;
- High pulp yield per unit, small area occupied;
- Low energy consumption and balanced consumption of steam and electricity avoid peak load;
- It takes less manpower. But compared to highly automated batch cooking equipment, the difference between them is not much;
- Cooking uniformity is better, even in the cooking process of large pieces of wood, sieve residue is less. However, there was no significant difference in pulp yield and strength between the two cooking processes.
Disadvantages of continuous cooking
- The flexibility and reliability of pulp production is not as good as batch cooking;
- In the use of fine wood chips, the impact on production of continuous cooking is greater than that of batch cooking;
- The recovery of turpentine is low.
Questions and solutions
Pump line blockage
- Analysis of causes
- If the concentration of the grass washing machine is large when the grass pump is stopped or the grass pump frequency is excessively increased when the grass sheet concentration is large, the pump inlet will be blocked;
- The grass pump line is not flushed by the flushing pump when the machine is shut down, causing blockage of the pipeline when starting up. When the machine is turned on, the grass pump runs for a long time and the oblique screw does not move on the grass, so that there is too much grass to block the entire pipeline;
- When grass is shorted in the normal production, the concentration of the hydraulic grass breaker is large.
- Preventive measures
- Minimize the concentration between the grass pumps;
- When the cooking is temporarily stopped, the wet materials preparation is not stopped, and the grass piece pump must be continuously fed with the grass; before starting the grass piece pump, the flushing pump is first opened, and when the grass piece pump is stopped, the flushing pump is stopped;
- Pay attention to the concentration of hydraulic grass cutter in normal production to prevent the grass pump from getting on the grass.
Feeding screw slip
- Cause analysis
- The moisture of feeding is large and the dewatering effect is poor;
- The screw shaft and the anti-slip strip are worn;
- The feeder belt is loose;
- The qualification rate of cutting grass is low, and the grass piece is too long;
- mildew and rot of grass;
- In the production, there is no returning of the drum and the material is broken, the feeding is suddenly large or small, or the cooking pressure control does not rise too fast in time.
- Preventive measures
- Calculate according to the amount of processed wheat straw, and carry out planned replacement of the screw shaft and anti-slip strip;
- Check the belt of the feeder every time after stopping machine, tensioned in time when it is loose, and replace it with new belt when it is too loose;
- Strengthen the inspection of the passing rate of incoming materials and replace the blades for cutting grass regularly;
- Strengthen the management of materials preparation, and timely remove the moldy and deteriorated forage;
- Pay attention to the amount of grass on the straw pump in the production, ensure that the return screw conveyor has enough material, and stable cooking steam pressure.