STEAM SYSTEMS/GAS INDUSTRY FEATURE
THE SPECIFICS OF STEAM SYSTEMS
Chris Coleman, boilerhouse national specialist, provides some of the principles that should help plant managers ask the right questions when planning and managing the upgrade of a steam system
W
ith so many variables to consider in the planning, management and
upgrade of steam boilers, it’s important for professionals to have a solid grounding in the “fundamentals of steam”. In turn, this will help to achieve better efficiency and safety. It is, however, commonplace for industry
understanding of steam systems to be somewhat limited. This is true across the board, whether your role is to simply ensure your plant is operating safely and efficiently, completely overhaul and plan a new steam system or identify, plan and implement steam and thermal energy efficiency improvements. Nevertheless, it is definitely beneficial to develop a basic understanding of the properties of steam before consulting an expert.
THINGS TO CONSIDER Meeting specification, deadlines, budget, safety and regulatory requirements, are but a few considerations that can cause the most accomplished of plant managers a headache. Not to mention energy efficiency targets and minimising downtime. Until it becomes a priority, much of the valuable background information you once had becomes a distant memory. Granted, there is a wealth of
information available on steam systems and sometimes it can be a minefield to navigate. Therefore, we have identified the core elements that will give you a basic understanding: the different boiler types, how steam is produced into three variants and the condensate loop. Develop your knowledge in these areas and you are already on track to an optimised solution.
SO, WHAT’S TO KNOW? In summary, shell boilers are the most common but there are many variations out there. And there are also three types of steam to know about – saturated, superheated and flash steam. As a versatile purveyor of energy, the way in which steam is produced and distributed both have a significant impact on its potential performance and economy for the end user. There are also technical materials worth being familiar with, such as steam tables which help provide more detail around the properties of steam at varying pressures. And, while condensate in itself is a much wider topic to comprehend, make sure you have an understanding of the way it is created and should be recycled. Based on all of this, there are a number of key tests that you should consider carrying out such as
Get to know what’s happening in the boilerhouse - it’s beneficial to develop a basic understanding of the properties of steam
feedwater treatment, deaeration and storage. Clearly it would not be possible to
upgrade a boiler ahead of conducting a full and thorough audit of the existing system. And, as with any piece of equipment in our industry, it will most likely not be a like-for-like for the system that is currently in place. Ask yourself two key questions: Has your facility changed in any way in terms of its requirements? Have there been any technological developments since the first install? By re-acquainting yourself with the
Chris Coleman, boilerhouse national specialist
fundamentals of steam, be it through written literature or industry training courses, you can build the requisite knowledge you need to identify areas of improvement so fewer problems or faults need to be dealt with in future. We have created a downloadable guide
to The Fundamentals of Steam to make your job easier when it comes to upgrading. Download it when you need it by the following link, or simply print it out so you have it to hand on site:
https://sxscom.uk/Fundamentals-of- steam
Spirax Sarco
www.spiraxsarco.com
RAPID STEAM GENERATORS SUPPLIED TO LARGE LNG TERMINAL
Babcock Wanson has completed a project for National Grid featuring two bespoke Rapid Steam Generators at its Grain LNG importation terminal in Rochester, Kent. The site is of strategic national importance to the UK’s energy infrastructure and security of supply. It is the largest terminal in Europe and eighth largest in the world by tank capacity (1,000,000m3
), and spans over 600 acres in total. Following a major project to substantially increase the LNG handling capacity at Grain LNG, which has seen new storage tanks installed with four
times the capacity of each of the originals, it was decided to upgrade the process heating system that converts the LNG to a gaseous state. Working closely with National Grid, Babcock Wanson has designed a steam generation system based on two of its 7000kg/h VPX Rapid Steam
Generators to replace the existing two 3.5 tonne boilers on site. The new vertical coil Steam Generators feature three full gas passes, plus an in-built combustion air pre-heater to give high operating efficiency. The
pressure containing coil design of the Steam Generators form the main combustion chamber with the second and third passes for the gasses going between the coil windings to ensure high gas velocity with good heat transfer and self cleaning of the flue gas passes. A purpose built and matched Babcock Wanson burner ensures long life and simple operation. The new Steam Generators at Grain LNG are fully automated with automatic unattended start and stop
capability. They have been designed with specialist PLC interfaces and controls, which also enable automatic changeover between the two generators on demand. They have also been adapted to operate at a lower steam pressure than is standard to work with the existing steam system on site. The Babcock Wanson Steam Generators are rugged in construction and include ATEX rated gas controls. To
ensure continued smooth operation, National Grid has agreed a maintenance service contract with Babcock Wanson, tailored to meet their precise needs.
www.babcock-wanson.co.uk PROCESS & CONTROL | FEBRUARY 2019 35
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