Choose the option that can handle a wide flow range and maintain strict temperature requirements.
Food and beverage applications must meet various process temperature and pressure control requirements to maintain strict temperature and help ensure product quality and safety. Choosing the right steam control system and using best practices for piping and installation can have a huge impact on the end user’s production, downtime, and health and safety. Consider using a 100 to 1 rotary shut-off valve to simplify the process and allow strict performance control and shutdown applications.
Steam control valves in food and beverage applications Steam control systems, including control valves, steam traps, and condensate recovery equipment, are essential in many food and beverage applications. The main applications include clean-in-place (CIP) processes and HTST (high temperature/short time) pasteurization for the manufacture of dairy products, cheese, milk and ice cream. Other widely used steam processes include steaming and sterilizing in canning operations; bottle washing machines; temperature-regulating hot water systems; whey (COW) water condensate; poultry scalding machines; flash peeling machines and bleaching machines; evaporators ; Direct steam injection process; and hot air drying system.
These applications all use temperature controllers with valves to maintain individual temperatures. Valves are critical because operators must maintain very strict temperature control to avoid problems that would otherwise occur, such as bacterial growth or product loss. The challenge for many food and beverage applications is that they usually do not have a set flow range. This change in flow range is especially true for factories that run different products at different times. For example, in many factories, the HTST pasteurization flow range can range from 10,000 pounds per hour to 2,000 pounds per hour. In order to maintain proper temperature control when the flow rate changes, the operator must use a control valve with a variable range and excellent closing characteristics.
Unfortunately, operators often use cookie-cutter methods to isolate steam on brewing process steam equipment. For example, many systems today include a pneumatically activated right angle rotary ball valve to help shut off steam entering the heat exchanger. Because of the leakage of standard globe valve applications on the market, they usually choose ball valves. Using actuated ball valves to isolate the process on the steam system can cause water hammer, pressure peaks, product loss, or bacterial growth.
In contrast, the rotary valve has good closing properties, which can meet the FCI ANSI V class closure of steam for these process applications. This eliminates the need for actuated ball valves on steam trains used in the isolation process. Some rotary globe valves use cam action, low-friction plug operation to provide a long-life tight shutoff in a variety of flow control applications. Their adjustable range is 100:1, allowing precise control of various flow rates. This enables the plant to use the same control valve for all steam and fluid control applications in the facility. Using one valve type in many applications can have great advantages because it allows factory standardization and minimal inventory requirements.
Best practices for the CIP process
The best practice installation of the CIP process can achieve a high level of expectations. The best practice settings were developed by Kevin Rasmussen, President of KEI Steam Solutions, Inc.
“The settings that are commonly used today usually require more service and maintenance because they are not properly arranged or selected, and they lack best-practice plumbing, which can cause equipment to malfunction,” Rasmussen said. "Using recommended best practices can increase productivity, reduce downtime, and ensure equipment reliability on the system. In addition to the best practice implementation shown, plant operators should always conduct annual evaluations of steam and condensate equipment, To ensure that the equipment is operating at the best level."
CIP systems in the food and beverage industry use steam to heat water in the process through non-contact heating through a heat exchanger or by injecting steam directly into the CIP tank. The rotary shut-off valve shown can be used for heat exchanger temperature control. Turndown allows maximum temperature and pressure control in various flow ranges. This is critical in CIP heating because the load changes are constant and the application requires consistent temperature control. This application needs to shut down very tightly when the system is not running, so there is no steam and condensate loss and heat exchanger degradation.
Another problem in food and beverage applications is steam traps and condensate return systems, which should quickly remove condensate for heat transfer and eliminate stall points. The best practice solution shown includes the elimination of condensate from the CIP heat exchanger.
The use of free-floating ball steam traps can continuously remove the condensed water on the heat transfer surface, thereby appropriately transferring heat to the product. Unlike standard float and constant temperature (F&T) traps, this free-floating steam trap does not have any mechanical linkage and has a variable orifice, which can be adjusted according to the continuous condensate load to achieve fast and efficient condensation Water removal and process temperature control.
In addition, the best practice setting also avoids stagnation or accumulation of condensate on the heat transfer surface by using a steam motor or a combination of a steam pump and a trap. When using a regulating control valve, all condensate pipes must be drained by gravity or pumped back to the boiler room. The ideal setup also includes a main pressure reducing valve to reduce the steam pressure from the main plant pressure to the CIP system.
It should be pointed out that the best practice implementation also enables the plant to use the energy saved by recycling the condensate, which is like "liquid gold" to the process. This type of setup helps the factory achieve the desired balance between energy recovery and food performance. It helps answer the question: "How can I maintain my control without having to install expensive extra bells and whistles?"
Large cheese manufacturing plants in the Midwest demonstrate best practices
To illustrate the advantages of a steam control system designed according to the best practices discussed, the following is an example of a large cheese manufacturing plant that has recently overhauled its equipment from automatic ball valve settings to rotary valve settings.
The Midwest cheese factory uses automatic ball valves.
The following picture (left) shows the "before" state and various improper practices: • There is no drip trap installed in front of the control valve to remove condensate to prevent the valve seat from drawing. • The device has an automatic ball valve for isolation before the control valve, which only provides on/off service. This may cause premature failure of the control valve and heat exchanger tube bundle. It will also cause instability in process control. • The piping of the control valve is too close to the inlet of the heat exchanger, which does not allow the speed through the control valve to expand when the pressure drops. The minimum should be 10 times the pipe diameter of the straight pipe section after the inlet of the heat exchanger is connected to the size control valve. • The heat exchanger should use a continuous trap or a variable orifice trap to continuously discharge the condensate, remove the condensate on the heat transfer surface, and make full use of the potential. • The condensate must be discharged to the condensate pump by gravity to completely drain the condensate.
This can be done with steam/air powered pumps or electric condensate pumps. • The device does not have a constant temperature vent to exhaust air when the heat exchanger is activated. • Without proper exhaust, the heat exchanger may experience delays in start-up time, improper heat transfer, and equipment air confinement. • There is no Y-shaped filter protection device in front of the control valve to allow the pipe to be drained and to remove scale and debris.
Best practice implementation, using rotary control valves.
The image below (left) shows a solution designed to follow the outlined best practices. The rotary control valve provides tight process temperature control and isolation in one valve. There is no need for ball valve isolation, because the rotary stop valve allows a 100:1 turndown ratio to achieve process control range, V-level shut-off, and larger CV.
Proper piping layout before and after the control valve to the heat exchanger can ensure the best performance. The feature of the new setting is the correct use of the thermostatic vent with a vacuum circuit breaker on the heat exchanger.
The correct discharge pipe using a variable orifice free float steam trap can continuously discharge condensate on the heat transfer surface. A proper drip bag and Y-type filter can protect the control valve from the effect of drawing on the valve seat. The gravity that discharges the steam trap to the steam/aerodynamic condensate pump or the electric condensate pump can properly remove the condensate from the heat exchanger. The pipeline after the expansion of the steam trap is set to include a pipeline diameter for the flash margin discharged by the trap.
Implementing best practices to obtain reliable service and control Best practice equipment selection, piping and implementation of procedures will lead to reliable long-term service and control of equipment and processes. Unfortunately, many food and beverage plant operators do not have the technical expertise to ensure that equipment settings are implemented correctly. They may rely on suppliers and process equipment suppliers to provide this service. This is why the promotion of best practices is essential to make the process run correctly. ______________________________________
Jason Carpenter has nearly 20 years of experience and is a skilled business project manager at CIRCOR International. Jason manages a portfolio of control valves, regulators, steam heaters, and steam belts for steam application solutions in the regional energy and processing industries, such as food and beverage, pharmaceutical, chemical, and pulp and paper in the American markets.
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Recently, the ADM Advanced Design and Manufacturing Expo was held at the Toronto Convention Center. So far, the largest part of the Expo is the trade exhibition area, which is a busy place. #ADMexpo #DiscoverEngineerBuild #manufacturing #design #packaging #automation #technology #plastics
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