Some issues regarding the operation of CO2 stripping urea unit
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:L :L :L :L Our plant is a urea unit with an annual output of 300,000 tons that was put into operation in June 2005. One month after it was put into operation, it reached the ammonia consumption level of 575kg/T.NH3. Later, the ammonia consumption remained at the level of 560-570 in 2006, and the stripping tower liquid temperature has been around 171-173. In July 2007, After the repair and maintenance of the stripping tower, the ammonia consumption dropped to 545~550, and the stripping tower liquid output remained between 167 and 171. However, in the last month, the stripping tower liquid output has been high between 173 and 175, and the ammonia consumption has reached between 565 and 570. The gas stripping efficiency is high and low, generally between 77 and 78, said the workshop director. It is suspected that the packing of the liquid ammonia pump clogged the small holes. After backflushing several times, the ammonia consumption is getting higher and higher. It was originally around 565 and is now around 570. However, the ammonia-to-carbon ratio has always been low and cannot exceed 3.0 (it used to be 3.1-3.2). The temperature has also been around 174. Because the Chinese New Year is approaching, the ammonia consumption is also lower than that of other plants. It’s not too high yet, so I want to complete the annual inspection, but I’m afraid of what to do if that’s not the reason by then, because I’ve seen the stripping tower liquid output at around 178 in other factories, and the inspection found that the stripping holes are not blocked, because the average ammonia consumption for three consecutive months is 549, so high ammonia consumption will have a great impact on the comprehensive ammonia production and urea production. So I want to discuss with you, are there any other reasons besides the air stripping tower? (Except for N/C reasons, there is basically a lot of ammonia added now,)
First of all, it is wrong that the liquid outlet temperature of 201C is high. Of course, each 201C has its own temperature range after being put into use! This is what you said: ‘'However, the ammonia-to-carbon ratio has always been low and cannot exceed 3.0. ； Have you checked the reason? ? If the material ratio (feed) is not ideal, resulting in a decrease in conversion rate, the load of 201C will be increased, as well as the N|C, get H|What is the value of C? I personally have similar working conditions to yours in my own factory, please tell me! Hope to communicate more!
:The handshake N/C ratio is 2.8~3.0, the H2O/C ratio is between 0.45~0.65, and the conversion rate is about 61%, which is quite high. The NH3 content in the stripper liquid is about 9.2 higher. The ammonia pump is basically a little faster than the previous two-machine model. The methane pump is slower than before. Because of the poor working conditions, I dare not lift the blocks. The methane liquid concentration is NH3 31%, CO2 36%, and H2O 32%.
I would like to know how the ammonia consumption of your factory is calculated, and how the measurement of raw materials is corrected, because I have a set of data here.: According to the reaction equation for urea production, the theoretical ammonia consumption per ton of urea is 566.667 kilograms. According to the current technical level, there is still a slight gap between practice and theory. It seems that the actual ammonia consumption value should not be less than the theoretical consumption
First of all, I am very surprised that the urea and ammonia consumption of the original poster's factory is so low. I am also engaged in the production of urea by carbon dioxide stripping. According to the theoretical ammonia consumption per ton of urea, one ton of urea calculated using the chemical reaction equation will consume 566.7KG of ammonia. Adding the moisture in the urea, calculated based on 0.5%, even if there is no ammonia loss, the theoretical ammonia consumption will not be less than 563KG. How come the ammonia consumption of your factory is between 545~550? , is there a problem with the ammonia or urea flow meter? Secondly, in order to reduce ammonia consumption, efforts must be made in all aspects of the system. The high-pressure system should increase the conversion rate as much as possible and reduce the ammonia content in the vented air. The low-pressure water should be added as little as possible. For granulation, the vented dust and ammonia should be reduced as much as possible. The high-pressure system should adjust the ammonia/carbon ratio. It is more appropriate to keep the output liquid of the stripping tower between 167 and 171, but if it is greater than 175, it is on the high side. Ammonia/carbon 3.0~3.1 is also suitable
Their desorption and hydrolysis system uses the absorption liquid of the synthetic ammonia hydrogen recovery system, so that the ammonia consumption is much lower. The situation we encountered here is similar to that in Louzhu. We will talk about it after we inspect it in a few days.
Sir, can your N\C be higher? A little above 3.1, H\C is still okay. Let’s keep the N\C at the previous point and see. What is the pressure of your current high-pressure coil? What is the temperature range of the output liquid of the synthesis tower? (Taking into account the following your local temperature and the insulation thickness of the synthesis tower) What is the pressure of PIC-213 (low-pressure steam drum)? As you mentioned, the N/C ratio is between 2.8 and 3.0, the H2O/C ratio is between 0.45 and 0.65, and the conversion rate is quite high at about 61%. The NH3 content in the stripper liquid is about 9.2. At this time? I hope you can provide the following temperature data of your high-voltage coil, as well as the corresponding load! ! Learn from each other * one time! !
I agree with the 7th floor, you can provide the online temperature point data in your system, and we can all discuss it together!