“At our Babrala plant we needed to improve energy efficiency and thanks to Honeywell’s advanced process control we were able to minimize variations at our two urea units which led to our expected efficiency savings. Honeywell’s teamwork and deep knowledge as a leader in automation in the fertilizer arena was instrumental in achieving the benefit target set by TCL.”
V.K. Bhatia, Unit Head, TCL
Tata Chemicals Limited (TCL) was looking to control rising energy costs and increase efficiency at its Babrala plant in India. The company engaged Honeywell to provide engineering services to design and implement advanced process control (APC) on its two parallel urea units.
The primary goal for installing APC on TCL’s urea plant was to minimize key variable variations and have constant reactor conversion, leading to energy savings and smooth process operations. With a tight five-month schedule to meet, Honeywell implemented a master controller for better optimization and control of all variables. Benefits of the APC implementation included:
Tata Chemicals Limited is India’s leading manufacturer of inorganic chemicals as well as fertilizers and food additives. Incorporated in 1939, the company has an annual turnover of over $1.5 million and is part of the $22.8 billion Tata Group, India’s foremost business conglomerate.
In the six decades since its inception, TCL has been continuously raising the bar in technical competence and gaining recognition as a leader and innovator. The company has an enduring commitment to protecting and enhancing the environment, serving and improving the communities in which it functions, and adhering to the highest ethical standards of corporate behavior.
The company’s state-of-the-art fertilizer complex at Babrala in Uttar Pradesh, a state in northern India, has a remarkable record in energy efficiency. This facility, which makes urea, has won several awards for environmental conservation and safety.
Inspired to reduce its energy consumption, TCL wanted to implement an APC solution at its plant in Babrala, India. Its primary goal was to minimize the variance in variables for energy savings and smooth process operations.
“We have two parallel urea units at our plant which had a high level of interaction and large difference in dynamics between the front and back end variables in the plant,” said V.K. Bhatia, Unit Head of TCL. “We wanted to achieve a reliable, safe and energy-efficient operation that decoupled the units as needed but still optimized our plant.”
Challenges for APC in the urea process included high level of interaction between the variables and recycle streams from back end to front end, control of the CO2 flow fluctuations, reduction in water cycles, and improving conversion and reduction in steam requirements downstream.
“We needed to achieve reduction in our high pressure steam consumption by controlling the CO2 header pressure and reduce the passive air in the system,” continued Mr. Bhatia. “We also wanted to provide safe and stable control of the compressors.”
TCL engaged Honeywell to provide engineering services to design and implement APC on the two parallel urea units in Babrala.
Honeywell’s in-depth knowledge and experience in APC solutions and willingness to implement an innovative master controller solution helped TCL achieve the plant-wide optimization and results needed to meet its energy consumption goal using Honeywell’s Profit® Controller technology.
The scope of the APC project included CO2 compressors, high and medium pressure sections, low pressure and vacuum sections and a process condensate treatment section. A complicated process, urea production involves the following steps:
Because the front end and back end of the plant had different dynamics, they also had different Profit Controllers. Honeywell deployed an innovative method of using a master controller.
Traditional advanced process control software contains predictor, controller and optimizer modules. Though it is a proven technique, often the optimization of one controller affects the stability of the other controller thereby affecting the overall plant optimization and stability. Disabling the optimizer module from all the APC controllers of a plant and having one unique optimizer solves the issues with a master controller meeting this exact purpose.
Honeywell employed several strategies to achieve this unique design. The Profit Controllers were designed to see all constraints related to machine safety and to optimize the CO2 header pressure. A second strategy implemented was to maintain passive air/oxygen percentage to its minimum limit by changing the air flow with change in CO2 flow which led to a reduction in excessive passive air and vent opening in downstream section.
“Our APC project not only met our expected benefits but it also improved the dynamic control of both the front end and back end of the urea complex significantly,” said Mr. Bhatia. “We had a smooth and seamless transition from DCS control to APC and the cooperation from Honeywell was unsurpassed in helping us meet our energy savings goal.”