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Steam savings: Five easy steps
25 January 2013
Rising gas prices and a need to cut CO2 emissions has led to an increasing focus on the efficiency of steam plant.While there are many ways to boost efficiency, often they involve considerable investment. Before embarking
It is always useful to get an idea of the cost of steam generation. All the calculations quoted here are based on a plant running 24/7 for 50 weeks a year. For the best results you need to attain the steam cost for your site. Approximate steam costs can be calculated easily by taking the fuel costs and calorific value and applying a rough figure for boiler efficiency. For a more accurate approach the amount of steam generated, fuel costs, water costs, water treatment costs and also boiler maintenance costs can be taken into account.
Steam trap testing A steam trap survey can easily identify leaking or faulty traps and provide significant potential savings. For example, it is not unusual for a site with 100 steam traps to find 15 to 20 are leaking. A leaking steam trap could be losing you up to £2000 per year, so the potential annual loss - and therefore the potential saving - is in the region of £35,000.
Replacing the traps could provide payback in months rather than years. The same survey will also identify blocked traps, which can significantly reduce process efficiency, affect steam quality and impact on the safety of the system.
Condensate return As the cost of steam rises with the increase in energy prices, so does the value of condensate. Calculating the value of condensate needs to take into account heat energy, water charges, the cost of water treatment and effluent charges. Based on typical costs of £3 or £4/t, a small steampowered process discharging 1000L of unrecovered condensate per hour, would be costing approximately £24,000 per year. In contrast, the savings made by the installation of an efficient condensate return system with associated pipe modifications, could result in a payback of less than six months.
Pipe insulation Although the cost of insulation can be high, the potential savings can deliver a rapid return on investment. Programmes are available to calculate the standing losses from unlagged steam pipes. All that's required to establish a realistic estimate is a simple site survey to identify the size of pipe and the steam pressure.
To quote an example of the benefits:10m of un-lagged internal pipe; a steam pressure of 10barg; an ambient temperature of 20Â°C; and a process running 24/7 can lose as much as £4500 per year. Simply installing 50mm of insulation to the 10m pipe length could reduce the running costs to £400/year.
Steam leaks A 1mm hole in your steam main could be costing £500 per year. A 2in isolation valve with a leak from the stem could be costing £750 per year. So if you think highlighting steam leaks is obvious, take a walk around your steam system and take note of any leaks from valve stems, safety valves, flanges and unions. You may be surprised how many you find.
Steam metering Steam metering itself will not directly save energy, but for good housekeeping it is an essential discipline.Metering from the boiler house provides accurate steam consumption statistics for a typical working day, and can be a useful troubleshooting tool. For example, a rise in oil consumption without a corresponding rise in steam production can point to a problem with the boiler.
Potentially, there are thousands of pounds worth of savings to be made by following these five simple steps. For the best results you may need the help of a steam specialist company, but elements of a preliminary audit can be carried out in-house. Based on the findings, a program of work can be identified in order to realise some serious improvements.