1、 Preparation before operation
1. Material verification
Verify the product name, batch number, and volume of the incoming materials to ensure consistency with the production instructions.
2. Equipment inspection
Check whether the heaters and evaporators of each effect are clean and whether the instrument display is normal.
Confirm that all valves (feed valve, steam valve, vacuum valve, etc.) are in the correct open and closed state.
3. System status confirmation
Check the validity period of the clearance certificate and hang a production status sign.
2、 Start and Run
1. Establish a vacuum system
Turn on the vacuum pump, sequentially open the vacuum pipeline main valve and each effect sub valve, and maintain the negative pressure of the system.
2. Feed and initial heating
Open the feed valve to inject liquid into the evaporator, and close the feed valve when the liquid level reaches about one-third of the height of the sight glass.
Open the steam blow down valve to drain the condensed water, then close it, slowly open the steam valve, control the initial pressure at 0.1 – 0.15 MPa, and adjust it to ≤ 0.1 MPa after stabilization.
3. Liquid level and temperature control
Maintain the liquid level of each effect at 2/3 of the height of the sight glass:
When feeding continuously, adjust the opening of the feeding valve to maintain a stable liquid level;
During intermittent feeding, manually replenish the liquid to the standard level.
Monitor the temperature, pressure, and vacuum degree of each effect to prevent material coking or leakage.
4. Key operating points
Discharge non condensable gas every 2 hours of operation:
The first effect heater is directly emptied;
2、 The three effect non condensable gas is pumped out by a vacuum pump through a balance tank.
Regularly discharge condensate water (once per hour for second and third effects):
Close the drainage valve of the connecting pipe → open the vacuum three-way plug to release the vacuum → drain the condensate completely.
3、 Concentrate and collect paste
1. Material liquid transfer
When the liquid reaches the target concentration, use vacuum to draw the second and third effect liquids into the first effect for further concentration.
2. Terminal judgment
Confirm the endpoint through specific gravity testing (usually concentrated to 1.25-1.4) or volume reduction.
3. Discharge operation
Release the finished paste from the discharge pipe at the bottom of the first effect heater.
4、 Shutdown and Clearance
1. Orderly shutdown
Close the steam valve → stop the vacuum pump → close the vacuum main valve → open the atmospheric valve to break the vacuum.
2. Residual liquid treatment
Drain all residual condensed water and concentrated residual liquid from each effect.
3. Cleaning and maintenance
Thoroughly clean the evaporator, heater, and pipelines, follow the cleaning SOP, and keep records.