Pain points in the urea evaporation area during hot seasons!
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This post was last edited by lxq700918 on 2009-9-8 at 16:52. Once the hot summer arrives, there are so many troubles caused by the evaporation of urea! Firstly, as urea evaporates, the condensation efficiency of the various surface coolers decreases, making it difficult to maintain an adequate vacuum level. As a result, it is hard to ensure that the moisture content in the urea product meets the requirements for high-quality products. The goal of achieving 100% high-quality product rate at the beginning of the year seems quite unattainable! Secondly: once the hot summer arrives, the material preparation tower seems a bit too small! Problems such as high temperature of the urea particles and sticking to the tower have reappeared... There are many other issues as well, but I won’t go into detail about them all. I wonder if those of you who work with evaporation experiences the same things? Or how do you solve these “troubles”? We welcome everyone to actively participate in the discussion and relieve some of your \"worries\"!
The last edit to this post was made by Fan Zhou Wu Hu on 2009-8-13 at 13:56. First of all, as urea evaporates, the condensation efficiency of the various air coolers decreases, making it difficult to maintain an appropriate vacuum level. As a result, it’s hard to ensure that the urea product meets the requirements for high-quality standards. The goal of achieving 100% high-quality output at the beginning of the year seems a bit unattainable! : It can increase the temperature of the second-stage evaporation; under the same vacuum level, the moisture content decreases by 0.05%. Secondly: once the hot summer arrives, the material preparation tower seems a bit too small! Problems such as high temperature of the urea particles and sticking to the tower have reappeared... : Making the louvers at the top of the granulation tower larger can help alleviate these issues.
In summer, the air humidity is high; when the amount of air entering the system increases, the issue of moisture also needs to be taken into account. Often, in the evening and early morning, we are forced to cover the air vents due to moisture problems
The last edit to this post was made by lxq700918 on 2009-8-19 at 17:29. First of all, the evaporation of urea leads to a decrease in the cooling efficiency of the various surface coolers, making it difficult to maintain an appropriate vacuum level. As a result, it’s hard to ensure that the urea product meets the requirements for high-quality standards. The goal of achieving 100% high-quality products at the beginning of the year seems quite unattainable! What kind of water do you use for the surface cooler? We use recycled water for everything here, but due to the high temperatures in summer, we switch to lithium bromide water. It’s impossible to modify the granulation tower in summer, but a humidity meter can be installed. The person in charge of evaporation should make sure to close the windows of the granulation tower; that should help
The last edit to this post was made by chqd315 on 2009-8-19 at 18:19. 1. Regarding the decline in the condensation efficiency of each air cooler due to urea evaporation and the difficulty in maintaining an appropriate vacuum level, it is possible to increase the temperatures of stage 1 and stage 2 as much as possible, provided that the standards for biuret are met； Also, whether it is due to an overly small design area of the surface cooler or insufficient capacity of the ejector can be resolved simply by making modifications. Alternatively, a urine pre-concentration system can be added to increase the feed concentration. 2. Solution to high temperature of urea pellets and sticking to the tower in summer: Purchase granulation nozzles with a small particle size, designed specifically for use in summer.
I believe that while the aforementioned issues are indeed important, the existence of polymers in the two-stage separator is the major problem that evaporation faces throughout the year.
The surface cooler needs to be washed frequently, and attention should be paid to the temperatures of the inlet and outlet water in the circulation system. For our two-stage separator, we wash it four times per shift; during each shutdown, hardly any biuret can be found in our two-stage separator. Fans have been installed on the conveyor belts at the loading dock to help reduce temperature.
I have a question for the Koala users: Do you use lithium bromide to cool the water during the summer? Is it limited to use in the air coolers of the evaporation system, or is it used throughout the entire urea system?
Due to inadequate design considerations, this has caused certain difficulties in the operational processes during the summer months. As a design engineer in this field, I feel that my work was not done properly; in fact, these problems – such as those related to the condensate in the two-stage separator, vacuum levels, particle temperature, and sticky towers – should be solvable. The key issue lies in economic considerations: high investment costs and high consumption rates. Additionally, these problems usually arise as a result of capacity expansion.