thePetroStreet

During my normal office work at Ammonia-Urea complex, I have heard an activity named "PTR, Production Test Run". Can any one tell me, whats its significance and how this activity is performed.

Direct measurement of solid product (Urea / DAP - Di Ammonium Phosphate etc.) is costly and mostly inaccurate. PTR or DBTR (Direct Bagging test run) is an indirect method to estimate real time production of solids based upon one of their raw material whose measurement is economical and accurate.

In case of Ammonia-Urea complex CO2 and NH3 are raw materials for production of Urea. As Ammonia delivered to Urea plant in liquid form (as compared to CO2 which is delivered in gaseous form), therefore, its measurement is easy to perform and quite accurate. So, Urea produced in a certain period of time (usually 24 hrs) is recorded (through bagging all produced Urea) and against that certain time, ammonia fed to Urea plant is measured. It is ensured that Urea plant is operated in steady state conditions and there are minimal changes in plant load during PTR. The ratio of Ammonia used per ton of Urea produced is estimated and used as a reference to estimate Urea production for upcoming days until unless there is major change in weather conditions.
For Example,
Urea produced within PTR duration= 1000 MeT/D
Ammonia Used During that period = 576 MeT/D
Ammonia to Urea ratio calculated=576 / 1000 = 0.576

On some fine day if Ammonia used at Urea plant is 700 MeT/D, Urea production will be estimated to be = 700 / 0.576 = 1215 MeT/D

Good explanation. But there will always be in accuracies in this system due to weather conditions and un steady state operations. So, what can one do to cope for these in accuracies. Also, please elaborate on the direct measurement issues? What is the cost outlook for this direct measurement?

dear Ahmed, it is not the weather only that affects the actual N/U ratio of a running plant. The other factors like changes in plant load, disturbances in plant operating conditions, recycling of Dissolved Urea to the process, system leakages etc also affect it. During normal operating days it is impossible to avoid such deviations and it is even more difficult and costly to keep the track of these changes and then incorporating it into your daily production sheet.

Talking about direct bagging test run, its not possible to bag out all the production daily mainly due to trucking availability issue, including offspec product issues, maintenance issues in bagging equipment etc. It is highly costly to store urea in bagged form. It will double the cost of truck loading process. It also demands a lot of space to store Urea in bagged form. The cheapest way is still Product test Run because after all this is just an internal measurement, custody transfer to dealer is logged through bagging.

I hope you have got your answer.....

thx