Evaluation of a large energy intensive site to detemine if centralised electricity generation and steam distribution is preferable to local generation

Lead Research Organisation: Cardiff University
Department Name: Sch of Engineering

Abstract

Steelmaking generates a range of combustible gases, generally of a low calorific value. Historically the cost of capturing, conditioning and storing these gases significantly exceeded the cost of natural gas. Process equipment developments over time have replaced gas by-product use with natural gas supply.Lowering the Carbon Footprint of steel production and rising energy prices demands a thorough review of energy use on site. Currently the site operates gas fired boilers mainly fired by process gas, generating high pressure steam for electricity generation and feeding a low pressure steam ring main for use across the steelworks. Additional package steam boilers supplement low pressure steam on site.Over decades the steel plant has developed with many changes introduced. Steam use is ubiquitous but it may not be the best option. The purpose of this research is to map current steam use on site and to determine other sources of low grade heat. The current monitoring and control of steam generation and use will be considered and improved control methodology proposed for any chosen system.Corus has commenced investment in excess of 60m to capture, condition and store more process gas, this research is key to determining how best this gas can be utilised on site.Combustible gases produced on site will be researched to determine optimum combustion characteristics, whether conventional combustion or gas turbine. Methods of generating electricity and or steam using low grade heat or process gases will be examined to determine whether these new methods would be preferable and use less energy than the current steam ring main. Alternative thermal cycles, for example Kalina, will be researched to utilise low grade heat for electricty generation and steam or heat raising.If beneficial uses cannot be found for the low grade heat on site, other uses for example district heating will be investigated.

Publications

10 25 50
 
Description This work has shown clear evidence that large energy intensive industries should invest in energy recycling as a medium to long term savings plan. This is particularly true where energy is moved around large sites, flaring occurs due to waste gas production or large scale waste heat is discharged to the atmosphere.



Utilising more waste heat sources and installing a new power plant, it will be possible to reduce site wide steam distribution; reducing distribution losses and increasing electrical generation.



It was found that with present gas turbine technology, the variability of the process gases characteristics and production volumes resulted in the requirement for the use of natural gas as a supplementary fuel. Any new power plant should be based up on a conventional multiple boiler and turbo alternator generator configuration, with the capability of producing low pressure steam for the distribution network. This wqill allow for an increase in total generating capacity, reducing the undesirable flaring of valuable process gases; and in conjunction with the implementation of the Centralised Heat Recovery strategy would support the drive for electrical self-sufficiency for the Port Talbot Steelworks site.



A substantial amount of medium (>400ºC) and high grade (>800ºC) thermal energy is available, a significant proportion of which could be captured using currently commercially available technology.



The use of waste low grade heat to replace the steam used at present for space heating could be used towards the creation of a hot water distribution system. Thus the steam that is currently used can then be made available for electrical generation.
Exploitation Route Where a large energy intensive industry can utilise the findings of this work is best shown by the direction TATA are moving to exploit the results of this project. As a direct result of this project the Tata operated steelworks in Port Talbot has taken a step towards being electrically self-sufficient, developing a strategy to utilise waste heat sources distributed throughout the site to generate steam which is to be used to produce electricity in a centrally located steam turbine. An initial investment by Tata of £53m based upon project recommendations has already resulted in energy savings equivalent to £5M per annum. The steelworks future aim is to utilise lower grade heat sources to displace steam currently used for space and process heating, releasing more steam for electrical generation and provide district heating to the local community. The information and results have been disseminated widely throughout the project and are continue to do so through publications in Journals and conferences; both national and international.



As part of the UKs (and global) commitment to reduce emissions all energy intensive industries can reduce their energy footprint through careful utilisation of their waste streams and careful management of their energy usage. In the particular case study of TATA steeworks they are investing in their ability to become energy self-sufficient (as described below) and also provide district heating to the local community.



Waste gas streams produced during an industrial process should be examined for there variability and using exisitng technology be used as a useful energy source.
Sectors Chemicals,Communities and Social Services/Policy,Energy,Environment

 
Description As a result of this project the Tata operated steelworks in Port Talbot has taken a step towards being electrically self-sufficient, with a strategy to utilise waste heat sources distributed throughout the site to generate steam, to produce electricity in a centrally located steam turbine. An initial investment of £53m, made based upon project recommendations, has already resulted in energy savings equivalent to £5M per annum. A Centralised Heat Recovery Strategy has been developed transforming the perception of steam, providing a financial driver for steam distribution networks and waste heat capture. Utilising more waste heat sources and the installation of a new power plant, it is possible to reduce site wide steam distribution; reducing distribution losses and increasing electrical generation. The variable low CV by-product gases require the use of natural gas as a supplementary fuel. A new power plant should be capable of producing low pressure steam for a distribution network. Suitably sized power plant will provide increased total generating capacity, reduced flaring; and support electrical self-sufficiency. Where there are vast quantities of waste heat a significant proportion of thermal energy could be captured using currently available technology. Large quantities of low grade heat are suitable for the application of the Kalina or Organic Rankin Cycle's for the generation of electricity. Low grade heat is a viable option for site-wide and community based district heating systems. The use of wasted low grade heat can be used for a hot water distribution system. Low grade heat sources can provide space heating and steam for electrical generation. There is clear evidence that large energy intensive industries should invest in energy recycling as a medium to long term savings plan. This is particularly true where energy is moved around large sites, flaring occurs due to waste gas production or large scale waste heat is discharged to the atmosphere. .
 
Description Flexible and Efficient Power Plant: Flex-E-Plant (EP/K021095/1)
Amount £1,997,000 (GBP)
Funding ID EP/K021095/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 09/2013 
End 08/2017
 
Description Combustion/explosion Health and Safety CPD material 
Organisation Tata Steel Europe
Country United Kingdom 
Sector Private 
PI Contribution The work and results of the work undertaken as a resuslt of this project has been included in the CPD course to the employees of TATA steel, which is run through the Universities GTRC.