The need to retrofit plant and machinery
Machines are manufactured today with "energy efficiency" and product quality in mind; outdated machines are not energy efficient. Retrofitting projects aims at increasing the use of cleaner and more efficient energy sources, lowering energy costs, and reducing the carbon footprint.
Meeting legislative and statutory demands is an additional benefit of retrofitting. Limiting greenhouse gas emissions, holding the temperature increase, reducing particulate emissions and SOx-NOx are some critical regulatory requirements that call for implementation of relevant retrofit projects at plants that are no longer compliant.
COP21, the environmental conference organised by the UN recently in Paris, has passed an international agreement applicable to all its 195 member countries to combat climate change. The agreement emphasises to hold the increase in the global average temperature to well below 2¦C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5¦C above pre-industrial levels, recognising that this would significantly reduce the risks and impact of climate change. This agreement will compel the cement manufacturers to execute relevant retrofit projects.
The general consensus of cement manufacturers worldwide is that retrofitting is the way to achieve specific energy consumption targets, optimise plant operations, maximise the production of blended cement, ensure compliance with environmental laws, etc. However, due to a variety of reasons, many plants are not able to implement a retrofit project. The services of a consultant can help cement manufacturers find the optimum technology for their particular operation and implement the project. Such services will develop the strategy to perform a feasibility study which will determine the approach and methodology, the execution schedule, keeping in mind the lowest capex and minimum downtime.
In a recent study at a cement plant, the steps to optimise the raw mill performance were identified. Its implementation would increase the production capacity of the grinding system and improve the energy efficiency of operation.
We can also cite as an example a South American quicklime process plant which has been in operation for two decades and uses vertical shaft kilns to manufacture quicklime. Though very energy efficient, an operational requirement of vertical kilns is to have a particle feed size of above 40 mm. To meet this requirement, the plant had to reject the fines, generating thousands of tons of "reject" material with particle size below 40 mm, though chemically it was a good raw material. The plant decided to convert rejected material into a product by installing a rotary kiln system that accepts finer feed size. The plant had three critical parameters in its favour; i.e., land and raw material availability and market requirement. Although this is not a typical retrofit project, it utilised "rejects" to make a product. It is a retrofit project in the sense that a novel idea was implemented which used a material which otherwise would have been wasted.
Capital investment could be a major factor in the decision to go ahead with a retrofitting project; however, there are ways in which the Return on Investment (RoI) of the end product pays for itself. The following objectives should be considered when carrying out a Feasibility Study.
a)Minimum downtime of existing operation while planning the retrofit system
b)Maximum availability of the plant with stand-by operation
d)Optimum integration plan
e)Other case-specific requirements
The sustainable growth of the industry depends on keeping pace with technology, meeting demands on emissions and improving efficiency and operational economy. Retrofitting is a social responsibility to keep the environment safe and healthy.
Manoj Thakur, AGM - Engineering PENTA India Technical Consultants Pvt. Ltd.