Plant & Works Engineering May 2022

22 | Plant & Works Engineering www.pwemag.co.uk May 2022 Energy & Environmental Management Focus on: Boilers, Burners & Controls Kieran Bennett explains how to select the right valve for steam temperature control. F rom beer brewing to cheese production, temperature control using steam is used across various applications in the food and beverage sector. The control valve is key, and precise specification is vital to optimise product quality and avoid production inefficiency. The choice of valve size and type is crucial to achieving these aims for effective steam temperature control. While steam isn’t the only method for temperature control in food and beverage production, it’s used by many producers because it’s a very effective method of conveying heat energy. From mashing and wort boiling at a brewery to pasteurising milk and making cheese, steam is used by food and beverage manufacturers across a wide range of applications. Combined with a temperature sensor and a controller, a control valve is fundamental to a steam system to regulate the flow. Cost saving through correct valve size specification Ensuring that the right size control valve is specified is an easy way to make cost savings since a common problem is that excessively large valves are often specified. The larger the valve, the higher its cost, and operating expenses can also increase, requiring greater resources for actuation. The challenge of using over-sized valves can apply to new projects as well as existing installations, where often it’s incorrectly assumed that like-for-like replacement is the correct requirement. On a recent project, a customer requested a replacement for a 40 mm valve for steam control. On initial enquiry with the customer, it emerged that the required valve was to fit 40 mm pipework. Unlike fluid control, the size requirement of a steam control valve will nearly always be a smaller diameter than its adjoining pipework. Also, as the original valve was installed over 15 years ago, advances in technology since then meant that in all likelihood a smaller valve could be used to achieve the flow and actuation requirements. Further investigation of their application took into account the volume of product to be temperature controlled, the available pressure and the timeframe within which they wanted their product to be heated. Aspects such as the surface area of heat transfer were also considered. Data returned from the calculations showed that a maximum valve size of 25 mm was required for the customer’s application, providing them with a cost saving from their initial request. For new applications, or the higher the number of existing valves to be replaced at a production facility, the greater the cost saving that can be achieved by correctly specifying valve size. Increasing the accuracy and performance Failure to correctly specify the size of valve for steam control can also impact accuracy and performance. For applications such as pasteurised milk production, accurate control is essential to ensure the right temperatures are met. Accurately achieving the required temperature gives optimum product quality, while inaccuracy and deviations can mean lower quality or ruined Choosing the right valve for efficient steam temperature control