Technical Paper September 2012

 

 

The LP Prilling Bucket For Urea

Mr. Liu Xiaodi Inventor of LP Prilling Bucket, Chief Engineer Beijing Aerospace Propulsion Institute (No. 11 Institute). E: liuxd2006@126.com

The LP Prilling Bucket for Urea and its support system are installed at the center of the prilling tower top. By means of the motor the bucket can rotate at a certain speed and make the urea melt entering the bucket and jet out by the centrifugal force to get into contact with the air coming from the bottom of the tower, where after the droplets shape up (almost spherical), solidify and cool.

Prilling machine

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1. Main design parameters of LP Prilling bucket The main design parameters of the LP Prilling bucket are determined by the following:

ü Prilling capacity ü Tower inner diameter ü Tower height (effective height for cooling) ü Barometric pressure ü Temperature ü Humidity

2. Features of LP Prilling bucket The LP Prilling bucket has the following features, which are critical for the performance: Surface cone The surface cone is the most important parameter for LP bucket, and it determines the surface pressure distribution and affects the speed distribution of the urea melt leaving the bucket, and thus affects the prilling area in the tower. The cone design must consider accordingly the capacity, tower diameter, etc. Typically the LP bucket surface cone is: 8~25°(varied accordingly) whereas for example a TUTTLE bucket cone is ≤5°(and almost fixed). Jet hole density—hole number per area on surface Theoretically, we wish the same number of urea particles or the same urea quantity scattered on every area of the tower cross section, but this is very difficult to realise. We realize the optimum distribution by calculating the best distribution of the jet holes on the bucket surface and thus realize the best particle scatter on the tower cross section. Typically the hole number (single level) at LP bucket top is more than 50% at the LP bucket bottom, while the TUTTLE bucket’s hole number is the same at every level. Direction of the jet holes The direction of the jet holes determines the distribution of particles over the cross section of the tower. The better of the distribution, the better the cooling effect and the better the crushing strength of the prills. The LP bucket has a different hole direction (horizontal) at the top and bottom, while with a TUTTLE bucket it is the same.

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Manufacture The manufacture techninque is the most important element for the performance of the bucket.

LP Bucket TUTTLE bucket Non-equilibrium ≤5 g-cm 7~15 g-cm Surface welding Before assembly After assembly in- and outside is welded outside is welded only Surface cone Perfect cone Almost cone Vertical welding Perfect straight line Almost line 3. LP prilling bucket references LP prilling bucket has a better performance, lower price, shorter manufacturing time and a better after-sales service. More than 500 sets have been in operation in China with capacities ranging from 480 mtpd to 3650 mtpd. Many urea plants replaced the TUTTLE bucket by the LP bucket achieving a significant better performance, for example Zhongyuan Co., Jinxi Co., Daqing Co., Jiujiang Co., Nanjing Co., Neimengtianye Co., Fuling Co., Sichuantianhua Co., Dongting etc.

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LP bucket for different capacities (20, 50, 135 mt/hr) For more information please contact: Mr. Lin Weidong, Agent of LP Prilling Bucket General Manager Sichuan Yuanfeng Chemical technology Consultation Co.Ltd. T: +86-28-83667798 F: +86-28-83667578 M: +86-13308097095 E: nmtech@vip.163.com Add: No.18-2-8 yihufanglin qingbaijiang district

Chengdu city, Sichuan Province, Post code:610300, China