Article

Well-water filtration at the Thatchers Cider factory

Practical examples Water filtration for sensitive applications 6 min read

Author: Jonathan Smith, territory manager (Northern Europe) of Donaldson's process filtration division

Industry: Cider

Problem: Thatchers Cider, a well-known British cider producer, was considering new possibilities for using water from its own well in order to make rational use of natural resources and reduce energy consumption.

Solution: Thatchers Cider has been ordering compressed-air and steam filtration solutions from Donaldson for several years, so it turned to our specialists to select the next filtration solution. As part of a resource-efficiency program, the company decided to use water from its own well to clean the process equipment. Donaldson proposed a three-stage cleaning system with backwashing, which is characterized by a high level of safety and low operating costs.

Рис. 1. Компания Thatchers Cider входит в десятку крупнейших производителей сидра в мире — Fig. 1. Thatchers Cider is among the ten largest cider producers in the world

Situation

Cider (Cider, Cidre, Siideri): this drink is popular in many countries, for example in the United Kingdom, France and Finland. No English pub does without a cider tap!

Thatchers Cider, located in the county of Somerset, is among the ten largest cider producers in the world. This family company, founded in 1904 and currently headed by the fourth generation, has always striven to maintain high product quality and over several decades has won many prestigious awards.

Using well water for cleaning

Thatchers adheres to the principles of sustainable development. The company is constantly moving toward saving energy and the rational use of natural resources. This project consisted of searching for new possibilities for using water from its own well. Until then, the well water was used only for purposes that did not require its purification, for example for washing trucks. The goal of the project was to install a reliable, efficient and economical filtration system that would make it possible to use well water for cleaning the plant's machines and equipment.

Thatchers Cider has been working successfully with Donaldson in the field of compressed-air and steam filtration solutions for several years, so it turned to our specialists with this question as well.

Рис. 2. Фильтрующий картридж Donaldson P-GSL N. Гофрированный фильтрующий материал из нержавеющей стали надежно задерживает разные частицы загрязнений, содержащиеся в скважинной воде — Fig. 2. Donaldson P-GSL N filter cartridge. The pleated stainless-steel filter material reliably retains various contaminant particles contained in the well water

Solution

Economical and reliable three-stage cleaning

Donaldson engineers proposed installing three-stage cleaning systems, and Thatchers accepted this proposal. At the first cleaning stage, filters P-GSL N remove particles larger than 5 microns in diameter (fig. 2). At the second stage, P-GLS N filters with a nominal pore diameter of 1 micron are installed. At the third cleaning stage, the following are used LifeTec™ series PP N filters. These nominal-cleaning cartridge filters achieve the highest quality of purified water.

The first and second cleaning stages: all-metal filter cartridges and backwashing

Why did the Donaldson project engineers use P-GSL N series filters in the first two cleaning stages? The choice of these filters is due to their high quality and low cost. The pleated filter material made of extremely fine stainless-steel wire mesh reliably removes various contaminants and particles from the well water. In addition, these cartridges are characterized by a high degree of retention on the filter surface. This is a necessary condition for cleaning using backwashing. Backwashing simplifies operation and reduces overall costs, since the user does not need to replace cartridges frequently: the differential pressure raised by the retained particles is restored after backwashing almost to the value characteristic of a new filter.

Рис. 3. На последней ступени очистки скважинная вода проходит через фильтры LifeTec PP-N — Fig. 3. At the final cleaning stage, the well water passes through LifeTec PP-N filters

In the described solution (and in many other applications), it is important that the P-GSL N series filters are approved by the US Food and Drug Administration (FDA) for contact with food products, and that no binders, adhesives, additives or surfactants are used in the production of the filters. Therefore, the filters do not release particles that could pass through the filter material and enter food products or beverages.

Low maintenance cost

The first two cleaning stages at the Thatchers plant are integrated into an automated clean-water backwashing system. Backwashing is performed at a set interval or is triggered when a certain level of differential pressure (500 mbar) is reached. The extremely high reliability of the all-metal cartridges reduces maintenance costs. Two PF-IG series housings each hold eight 30-inch cartridges.

The filtration of water and other liquids is not the most common application of P-GSL N filters. These filters are often used for the cleaning of gases or saturated steam in sterilization systems. In such an application, support for backwashing and high thermal resistance up to 200 °C (392 °F) are important.

Рис. 4. Два корпуса PF-IG из нержавеющей стали вмещают по восемь 30-дюймовых картриджей P-GSL N — Fig. 4. Two stainless-steel PF-IG housings each hold eight 30-inch P-GSL N cartridges

The third stage: nominal-cleaning cartridges

In the third cleaning stage, LifeTec series filters are used. They differ in a different filtration technology and different cartridge materials (fig. 4). They are designed for the pre-filtration and fine filtration of liquids in the field of food and beverage production. The material of these filters is characterized by a very small pore diameter in the submicron range; in this case — 0.4 microns. They also differ from previous-generation filters in a more rigid polypropylene sleeve of the filter element, whose diamond-shaped structure improves the static properties and creates favorable conditions for the flow. The sleeve design significantly increases pressure resistance and has increased torsional rigidity.

Elements are available in four sizes — 25, 50, 75 and 100 cm (10, 20, 30 and 40 inches) — with pleated filter material depending on the application. The elements can be equipped with seven different types of connections for use in all common housings. Using several housings increases the reliability of the solution and reduces costs. In addition, this makes it easy to replace individual filter elements.

Рис. 5. Доступны четыре размера новых фильтров LifeTec с гофрированным фильтрующим материалом: 25, 50, 75 и 100 см (10, 20, 30 и 40 дюймов), а также исполнения с семью типами соединений — Fig. 5. Four sizes of the new LifeTec filters with pleated filter material are available: 25, 50, 75 and 100 cm (10, 20, 30 and 40 inches), as well as versions with seven types of connections

Along with a high ability to retain particles, LifeTec PP N filters are favorably distinguished by compatibility with a wide range of chemicals and resistance to sharp pressure fluctuations. These filters withstand up to 100 steam-sterilization cycles.

An economical solution for efficient cleaning

All three filtration stages meet the requirements of the US Food and Drug Administration (FDA) for materials in contact with food products, in accordance with Title 21 of the US Code of Federal Regulations and EU Regulation 1935/2004. The cleaning system is currently in use at the Thatchers Cider plant and satisfies all the requirements placed on it: well water can now be used to clean the plant equipment; drinking-water consumption is reduced; support for backwashing the stainless-steel filters lowers cleaning costs.

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