The dairy processing industry faces many challenges. The toughest and overwhelming majority of them involve minimizing product and utility waste while adhering to the highest process and product quality standards. Efficiency is especially pertinent during the clean-in-place (CIP) process, as dairies are required to thoroughly clean and sterilize equipment throughout production. Without proper measurement, the CIP process can become a significant cost source.

Although dairy plants manufacture a variety of dairy-based goods, they all traditionally share the initial processing steps in common.

First, milk is delivered from tankers to cooling tanks at the plant. It is separated and standardized into major product categories (skim milk, whole milk, and cream) then pasteurized to significantly reduce spoiling microorganisms and destroy pathogenic bacteria. Finally, the milk is homogenized to reduce fat globules and reduce/prevent creaming.

At each stage, the plant and its process equipment must maintain scrupulous cleanliness, which requires cleaning-in-place. While CIP is vital to the hygienic practices of dairy plants, it can also be a source of inefficiencies. Accurate and reliable measurement of flow, level, pressure, temperature, and conductivity to reduce waste by utilizing hygienic instrumentation that meets sanitary design standards and practices is of utmost importance.

CIP programs differ from application to application but traditionally they consist of three basic steps:

Flushing: Dairies typically start their CIP process by running warm water through the pipes for a predetermined amount of time.

Chemicals: An alkaline detergent and/or acids are circulated at a temperature between 140–167 °F.

Heat: Hot water is circulated to disinfect the piping and rinse out any remaining chemicals.

These steps present measurement challenges that can induce energy loss and create waste, which ultimately leads to a higher cost of operation.

Since all dairies run a CIP program, they also face the same challenges. In the following section, the seven common CIP efficiency challenges are presented along with seven solutions in the form of proper measurement instrumentation.

During the CIP program, condensed steam (i.e., condensate) is collected in steam traps and a condensate tank before being pumped back to the boiler. If the steam trap is failing, steam can be lost and require more energy to keep the plant running. Effectively monitoring the health of the steam traps ensures energy is not being wasted, thus decreasing energy costs as well as maintenance hours. See Figure:

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A wireless acoustic transmitter allows visibility into steam traps and pressure relief valves by accurately communicating acoustic level and temperature data. This allows for constant monitoring of steam trap parameters, health. Steam trap monitoring software provides real-time, continuous information about steam trap conditions, energy usage, and emissions.

Dairy processing uses more energy than any other sector of food processing. Large energy usage translates to high costs if not properly managed. The CIP process, especially, accounts for a major portion of this energy use. In dairy plants, steam is used extensively for sanitation and cleaning during the CIP program. Inaccurately measuring steam while using it to clean equipment can be costly for plant operators. Therefore, selecting high-quality instrumentation allows a plant to reduce steam usage with accurate measurement.

Multivariable differential pressure (DP) transmitters can accurately measure the flow of steam, ensuring it is used efficiently and effectively. Ultimately, this leads to a great energy cost reduction.

During the CIP process, any product left over in the circuit will be unusable as soon as it encounters the caustic chemicals used for cleaning. Pigging, a common practice used to clean pipes, often cannot be performed as intrusive measurement sensors, which penetrate a pipe, would be damaged by the pig. Utilizing non-intrusive process temperature measurements allows operators to utilize pigging-like processes to harvest additional product before the CIP program begins, resulting in less product waste.

A surface temperature sensor allows for accurate process temperature data without the need for thermowells or process penetrations that would impede the use of pigging. Using an advanced surface temperature sensor that uses a thermal conductivity algorithm measures the ambient and pipe surface temperatures and calculates an accurate and repeatable process measurement.

As mentioned in the CIP overview, large tanks are used to hold chemicals utilized in the CIP process. Making sure these chemicals are used efficiently is vital to reducing costs and ultimately saving money. Optimizing chemical usage and storage by utilizing accurate level measurement and reliable high level alarms ensures no chemicals are wasted during the CIP process.

A hygienic pressure transmitter with high accuracy at low pressure ranges allows for repeatable and accurate readings. This ensures reliable hydrostatic level measurements at all times. A hygienic fork switch allows for accurate level readings. Adjustable switching delay prevents false switching in turbulent applications.

Some of the most critical CIP measurements are return temperature and conductivity. Accurate temperature measurements with drift alert and hot backup ensures temperature stays online and limits the need for additional CIP runs. Conductivity is important to detect what fluids returning to the CIP skid may be water, milk, chemicals etc., as they all have a different conductivity. So when the conductivity changes, it is assured the milk/water/chemicals were flushed out and the next process can start without additional processing of CIP.

A hygienic four-electrode conductivity sensor is intended for measuring conductivity in the pharmaceutical and food & beverage industries can be utilized to accurately measure conductivity. The broad dynamic range of the sensor (1–1,400,000 uS/cm) makes it ideal for CIP applications. It also allows for quick responses to the needed temperature changes.

A surface temperature sensor allows for accurate process temperature data without the need for pipe penetration. In addition, non-intrusive temperature measurements can help monitor temperatures in hard to measure places, ensuring that CIP processes are not running longer than necessary. This, in turn, limits waste of chemicals and utility heat.

During the CIP program, it is important to be able to detect different phases in the process. This allows the plant to differentiate between milk, water, and caustic chemicals. When a plant has access to this information, they can fully utilize the product and minimize waste. Knowing the process phase also allows for quicker changeover from CIP back to product production.

Utilizing density measurement phase detection, such as a Coriolis meter, allows dairies to identify different densities of the product, effectively making plant operators able to detect the difference between the product, water rinse, and caustic cleaning solution.

The CIP process requires that the liquid moving through the pipes maintains a certain velocity for optimal cleanliness. Liquid moving too slowly can leave behind undesirable chemicals and spoiled product. Utilizing accurate velocity measurement allows for plants to maintain the highest degree of sanitation.

A hygienic Coriolis transmitter should be utilized to provide the most accurate measurement of velocity. It can calculate derived variables such as volume flow rate, flow totals, and concentration measurement, which can then be translated into an output signal useful for process control.

Reducing waste and increasing efficiency are key to running a successful dairy processing plant. With these seven instrumentation solutions to common CIP challenges, dairy plants can save time and money while increasing productivity.

For more information about dairy solutions, click here.

Image credit: ©stock.adobe.com/au/Renar

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