A typical modern ammonia-producing plant first converts natural gas, liquified petroleum gas, or petroleum naphtha into gaseous hydrogen. Starting with a feedstock heavy in methane as a main component. The initial step in the process is to add steam, and the mixture goes to two reformer reactors where hydrogen plus carbon monoxide is formed. Air is the main source of the nitrogen required for the ammonia reaction.
Before the feedstock can be converted to ammonia, several components, such as: sulfur, oxygen, carbon monoxide and carbon dioxide need to be extracted over several pre-treatment processes, since they can ruin the catalyst. Any remaining carbon dioxide and/or carbon monoxide are converted back to methane in the methanation reactor. Finally, the stream then enters the final ammonia synthesis reactor, where desired end-product ammonia is produced by reaction of hydrogen and nitrogen. This step is known as the ammonia synthesis, also referred to as the Haber-Bosch process.
About 80% of the ammonia produced by industry is used in agriculture as fertilizer. Ammonia is also used as a refrigerant gas, for purification of water supplies, and in the manufacture of plastics, explosives, textiles, pesticides, dyes and other chemicals.
In order to extract the most, i.e., to get significant economic benefits from the ammonia plant, tight control of several key important variables need to be maintained, such as:
- Hydrogen to nitrogen ratio
- Steam to hydrocarbon ratio
- Carbon monoxide/dioxide production and removal
- Amount of inert gases
- Waste water purity
- Ammonia flaring
- Efficiency of steam production unit
These complex but advanced (APC) and tight controls of entire ammonia production unit can give remarkable monetary benefits and savings such as:
- Lower fuel costs
- Lower steam production
- Higher yields and
- Overall optimized ammonia process efficiency
For ammonia processes PiControl Solutions DCS-based APC (Advanced Process Control) can typically ensure 2-4% increase in profit, smoother plant operation, automated loading and unloading and less work for the operators. BUT, prior to any advanced process control (APC) project, base-level PID loop tuning is a critical pre-requisite step. Unless base-level PID control loops are well tuned, advanced process control (APC) cannot work well.
PiControl Solutions benefits of PID loop tuning are amazing, such as:
- Reduction of the oscillation amplitude by 35 - 50%
- Increase of the controller action by a factor of 2 or 3
- Smoother and more stable operation of ammonia process and
- Avoiding unnecessary process problems such as: damage and/or to fast wear and tear of the equipment, plant irregular shutdowns or off spec product properties and/or grades
PiControl Solutions LLC has extensive experience in PID tuning and advanced process control inside of existing DCS. We understand the economics factors that drive the profit margin and have unique and novel closed-loop system identification technology, which tune and optimize base-level PID control loops quickly, efficiently and precisely. With our closed-loop technology we can perform system identification and PID tuning optimization of the following critical base-level PID controllers easily. Moreover, all process and data analysis and PID tuning and optimization work can be easily performed remotely by PiControl Solutions process control engineers.
We focus to analyze the process and provide the right economic advanced control solution for each ammonia process. The main opportunity for achieving APC (advanced process control) benefits is based on the fact that the ammonia production process is not very interactive, it is rather serial process. Poor control, oscillations and deviations in one control loop can cause problems only in the downstream unit, but not upstream of the process since the process is very sequential. Our DCS-based APC (advanced process control) methodology has proven particularly successful in many areas.
PiControl is an innovative process control software and services company that offers state of-the art, modern solutions at a lower cost, implemented in shorter time compared to competitors. PiControl Solutions is the only process control and automation company in the world which can perform any advanced process control (APC) project completely remotely. Over this low cost online/remote approach huge travel and accommodation costs can be saved and human health and safety can be kept on the high level.
For more information and details, please send us an email: [email protected] or call the Tel: (832) 495 6436.
Thanks for quick sumamry, request for detailed scope of APC, if you can share for typical ammonia / urea process. I am working on new fertilizer project for Western Australia.
Regards,
Rajesh Soni, Principal I&C Engineer