The processing of many food and beverage products requires subjecting the product to high temperatures for a period of time, thereby sterilizing the product. Traditional techniques, such as canning, expose the product to high temperatures for extended periods of time. Canning not only has a high energy cost, but also subjects the product to thermal stress, which frequently has a negative impact on the flavor and texture of the product.
More recent techniques involve aseptic processing, in which liquid foods and beverages are sterilized outside the package using an ultra-high temperature process that rapidly heats, and then cools, the product before packaging. The processing equipment allows the time (generally 3 to 30 seconds) and temperature (195° to 300° F.) to be tailored to place the least amount of thermal stress on the product, while ensuring safety. The rapid heating and cooling aspects of the aseptic process substantially reduce the energy use and nutrient loss associated with conventional techniques. As a result, aseptically packaged products retain more nutritional value and exhibit more natural texture, color, and taste.
The rapid heating and cooling steps of the aseptic process typically take place while the product is being piped from one vessel to another. A portion of the pipe is heated and, as the product passes through the heated portion of the pipe, heat is transferred to the product. The product within the pipe is under pressure, typically 50 to 100 psi, which serves to move the product through the pipe and also prevent vaporization of the water component of the product within superheated sections. Subsequent operations, such as packaging, normally require lower pressures, typically up to 15 psi. Thus, the product must go though a pressure reduction step before packaging.
Many designs of back-pressure or pressure reduction valves exist for single-phase fluids. However, these valves cause significant shear damage to sensitive fluids and particulate-containing liquids. Moreover, the valves can become clogged with particulates, which can damage the valve and potentially cause a rupture.
Accordingly, there is a need to provide a pressure reduction valve that can be used to transfer a continuous flow of particulate-containing material from a higher pressure environment to a lower pressure condition without significant damage to the particulates contained in the material.