The effective operating time of diaphragm evaporation is short
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This post was last edited by sunjl1981 on 2013-1-7 00:07. Seeking advice from experts: Our company uses a three-effect countercurrent evaporation system, and after each cleaning cycle, the effective operating time is only 40 hours. How can this problem be solved? Medium-pressure steam is used in production; the pressure in the first stage is 0.55–0.6 MPa, and the temperature is 140–145°C ； Three-effect vacuum level: -0.07 MPa ； Electrolyte concentration: 115–125 g/l ； The material transfer pump has a flow rate of 25 cubic meters per hour, a head of 32 meters, a rotational speed of 2900 revolutions per minute, and a motor power of 7.5 kW ； The salt extraction pump has a flow rate of 25 cubic meters per hour, a head of 30 meters, a rotational speed of 2900 revolutions per minute, and a motor power of 7.5 kW ； Alkali residue recovery enters the system ； The liquid caustic product contains 70–85 g/l of salts. # hcbbs
Based on your data, your ultimate vacuum level is too low; it needs to be increased to at least 0.08 MPa. (Gauge pressure) cannot ensure alkali output; a high salt content in the system inevitably shortens the cleaning cycle. Additionally, it is recommended that the electrolyte concentration not be lower than 120 g/l. You did not specify the heating area of your three effectors and the salt harvesting conditions. You need to pay attention to the salt extraction efficiency.
I’m not sure how the original poster managed optimization of the control system; here we also experience frequent issues with efficiency. Our vacuum level is at -0.075 MPa, and it seems that the current operation method is intermittent: L
Based on the data provided by the poster, the steam pressure is not high either; generally, only when the steam pressure is above 0.7 MPa can the concentration of alkali be high and steam loss be reduced； Moreover, it is not clear whether a water jet pump or a water ring vacuum pump will be used for creating the vacuum; in cases like diaphragm evaporation, the vacuum level needs to be below -80 KPa.
Thank you all! We use a water jet pump, with a pumping capacity of 50 m3/h ； Head: 80m ； Evaporator heat exchange area: 72 ； Should we consider replacing it with a larger hydrocyclone? Please give me some advice!
It is best to check the salt content of the clear liquid coming out of the centrifuge; poor salt extraction efficiency directly leads to a shortened washing cycle
Maintain stable liquid levels for the three effectors; it is ideal if the level control can be automated. What is the separation efficiency of the hydrocyclone? The salt content of the mother liquor produced by the centrifuge also affects the production cycle and yield.
The three-effect alkaline solution contains 70–85 g/l of salts (in the finished product)； Where should I start mainly (equipment? Operation? ） ； Provide guidance.
Are you forming a solid salt at the moment? ? If salt formation does indeed occur, the following measures should be taken: 1. Maintain a stable liquid level, as a drop in liquid level is the most likely cause of salt formation. We didn’t use computer control; for three-effect counterflow systems, the highest cost I’ve seen was around 30,000 to 50,000 yuan. 2 Observe the effect of adjusting the rotary salt separator; using a stereoscopic microscope, ensure that the liquid mixture does not turn white for an extended period of time. 3 Check whether the centrifuge filter cloth is damaged; the mother liquor needs to be salt-precipitated again. If 30% alkali is produced, the color of the output should not be the same as that of plain noodle soup; there shouldn’t be any problems with 70-80%. It’s unlikely for the alkalinity level to be above 70. How do you determine the “effective operating time”? What phenomena occur when it exceeds the “effective operating time”? ? What you are providing now cannot be used to determine the cause. If the product has a high salt content, cooling and sedimentation is all that’s needed; nothing else. This post was last edited by yzhms on 2009-4-13 at 22:30.]
The finished alkali has a high salt content; if it’s not a cooling issue, then it’s necessary to check whether the filter cloth of the press is damaged and whether enough time has passed for the alkali to settle.