DSI for Sanitation, Sterilization and Cleaning-In-Place

Among the most important aspects of any food, beverage or pharmaceutical processing operation is the ongoing assurance of sanitary equipment. Effective cleaning is the best defense against product contamination — something to be avoided not only for health and safety reasons, but also for its ability to impact brand perception and raise the specter of lawsuits and product recalls.

 

As defined by chemical engineer Herbert Sinner in 1959, cleaning processes rely upon four basic principles: time, action, chemistry and temperature (TACT). The relationship between these principles is sometimes referred to as Sinner’s Circle; the circle shape represents the need for all four to work in harmony to produce an optimal cleaning environment.

 

Sinner’s Circle is instructive with regards to correct temperature: In short, its importance cannot be underestimated. While there are several methods to heat and supply sanitation water within a processing plant, none is more precise, reliable and safe than Direct Steam Injection (DSI) — a concept patented and perfected by Pick Heaters.

Sinners Circle

Figure 1: Sinner's Circle illustrates the relationship of time, action, chemistry
and temperature (TACT) to the cleaning environment.  
Source: Johan Gustafsson / CC BY 4.0

Although commonly employed to heat water for sanitation purposes, indirect heat exchangers and tank steam spargers present significant drawbacks; these include inefficient heat transfer, extensive maintenance requirements and the need for a considerable plant footprint. Manually operated steam/water mixing tees, which are also commonly employed to provide sanitation water at individual hose stations, pose a significant safety risk often due to improper operator adjustment or valve sticking caused by hard water scaling.

 

By contrast, compact and low-maintenance Pick Heaters DSI systems can be employed as a central heating system isolated from individual use points, while accommodating the wide variations in water flows and frequent start-stop applications typical of sanitation and clean-up needs. The systems blend pressurized steam directly into a process fluid to achieve 100% heat transfer, with temperature control within a +/-1° C range.

Many of DSI’s advantages are directly applicable to clean-in-place (CIP) systems, which are used to perform cleaning within the same piping path traveled by the product itself. CIP systems allow vessels, process lines and equipment to be cleaned without the need for removal or disassembly. The technology plays an integral role in industries requiring high levels of hygiene, and offers numerous advantages including maximizing production time and product consistency, reducing water and energy usage, and ensuring greater levels of worker safety.

 

CIP systems typically employ caustic wash cycles along with multiple rinse cycles. Because different industries operate within different cleaning parameters, the setup of CIP systems varies. When an additional sanitizing rinse is required before the next production run is started, for example, the importance of precise temperature control within the system becomes paramount. Sanitizing agents based on chlorine can be less effective at lower temperatures, while corrosive to metal equipment at higher temperatures.

 

Precise temperature control is also especially important for CIP systems in dairies. Milk and other dairy products are particularly vulnerable to spoilage and contamination from microorganisms such as E. Coli, salmonella and listeria; the equipment used for processing must therefore be cleaned according to very specific time, chemistry and temperature guidelines.

 

In pharmaceutical processing, moreover, CIP systems must comply to exacting standards more rigorous than those found in other industries. CIP employed in both pharmaceutical and extended shelf life (ESL) product processing plants typically adds a sterilization cycle to ensure the destruction of harmful microorganisms. This is sometimes referred to as sterilization-in-place (SIP).

Figure 2: Example of Pick CIP packaged system.

In one of many case studies on the effectiveness of DSI, Pick Heaters installed an instantaneous CIP heating solution for a dairy plant experiencing frequent and costly failures of its shell-and-tube heat exchangers. In another case study, steam injection was used in a dairy operation for both CIP sterilization and in-line pasteurization of soy milk. Packaged systems offering complete, single-source solutions are also available; Pick Heaters installed a fully-automated CIP system for storage tanks at a pharmaceutical company.

 

DSI has made inroads into numerous industries, and Pick Heaters are employed in applications ranging from process heating to plant sanitation to in-line cooking. Systems can be custom designed to fulfill a variety of functions within processing plants; CIP is just the beginning. For more information, contact us.

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