Correct application is key to heat exchanger choice

Paul Boughton

Modern heat exchangers have to be compact, durable, easily installed and simple to maintain. They also must be the right solution in the right place. Eugene McCarthy reports.

HRS Process Technology has supplied heat exchanger and pump solutions for an aseptic fruit processing plant in Oxnard, California. The system, which includes a DTA-series heat exchanger and a BP8 and BP10 pump, will process 4t/h of aseptic sliced and diced strawberry in syrup.

This is the second time HRS heat exchangers have been involved in a project with the Oxnard plant. Industrial treatment of products with particulates, such as whole or diced fruits for example, can be challenging for food processors as the product itself can be easily damaged. The combination of the HRS' DTA-series heat exchanger and BP series pumps guarantee zero damage to the particulates whilst maintaining product integrity and shape.

Featuring large dimple corrugated tubes, the DTA-series heat exchangers are ideally suited for food applications.

Corrugated tubes

The movement of the product generated by the corrugated tubes ensures the gentle agitation of the product through the tube and guarantees the thermal process without degrading the product and keeping it intact.

"Chopped fruit and vegetables, which are aseptically packed in a convenient ready-to-use form, have become very popular for commercial use.

"The reason for this lies in their high added value compared to canned products and their ease of use for transformation companies that use them for commercial production of convenience foods. The success of our technology for fruit aseptic plants is based on our corrugated double tube heat exchangers, piston pump, and our aseptic filler. Combining them makes it possible to process the fruit pulp and purée while minimising the undesirable thermal effects and getting a reliable, hygienic and well controlled filling process", said Carlos Cobian, general manager, HRS Process Technology.

Exhaust gas cooling

In innovation news, HRS has launched its new G series heat exchanger for exhaust gas cooling applications (Fig.1). A new design that provides a superior thermal performance with increased efficiency, the G series has been introduced to the market with a compact design to minimise pressure drops whilst maximising heat recovery efficiency and reducing process costs. The corrugated tube technology enables HRS to provide more compact units, ensuring higher heat transfer rates than smooth tube designs.

The heat exchangers' key features include a larger diameter interior tube, a full stainless steel design to provide robustness and durability and an expansion bellow fitted within the outer shell to absorb the differential expansion between the shell and inner tube.

Steel solution

Outokumpu, a world-leading company in custom-made products in coarse, special stainless steel (quarto) - has invested heavily in its rolling mill in Degerfors, Sweden. Cooling the machine shop to enable it to provide the best service to the rolling mill is of crucial importance.

The investment will enable a 30 per cent increase in the annual production of hot-rolled stainless steel plate, to a total of 155,000tonnes.

However, the investment increases not only the production capacity, but also the product's dimensional accuracy and performance.

To cool the rolling mill's machine shop, Outokumpu has chosen a solution that saves energy compared with more conventional alternatives. There are two ways to cool the machine shop. One is to use outdoor air, the other to use industrial water from a nearby river and cool the air through existing cooling coils and a SWEP B649 brazed plate heat exchanger (BPHE).

The plant is optimised for seasonal changes in order to constantly maintain the right temperature, while minimising the energy consumption of the pumps.

Outokumpu's Peter Svedrin is project manager for the installation at Degerfors, and responsible for ensuring the quality of the cooling and ventilation in the machine shop. "Unless the space is cooled, it may become too hot," he says. "There is an increased heating effect when more power is installed in the plant. The heat must be removed to prevent the equipment from ageing prematurely. This is why the temperature must be a consistent 24°C in the machine shop throughout the year."

SWEP's B649 is used to transfer cold from water drawn from the river out into the system via a loop. The river water is used as an alternative to outdoor air. The air is cold enough in late autumn, winter, and early spring, but in summer the river offers an alternative.

In the most recent winter, the heat exchanger only needed to use a fifth of its dimensioned effect. When the highest seasonal temperatures are reached, the BPHE helps to remove 1.2MWh excess heat.

David Ingvarsson, application engineer at SWEP, is pleased that the company's heat exchangers are meeting the customer's demands for cooling equipment using river water: "We are delighted to contribute to environmentally sustainable solutions. We offer a capacity that matches the space available in the machine room, and our product is vitally important to Outokumpu in this application. The heat exchanger's operational dependability is key to preventing costly downtime."

According to Svedrin, Outokumpu's choice of SWEP for this installation was based on a previous partnership, in which a 2007 feasibility study led to the successful installation of heat exchangers in 2008.

"The results of SWEP's delivery were positive in terms of design, technology, economy, and functionality," Svedrin says. "We had a teamwork that worked very well, and we had great support from SWEP. They delivered what they promised."

Heat transfer solutions

In business news, Alfa Laval has acquired Niagara Blower Company (NBCo), a manufacturer of energy-efficient niche heat transfer solutions.

The company's products are engineered-to-order, and particularly suited for use in the oil and gas processing industries. They are also used in a wide range of other industries, such as power, food and beverage and pharmaceuticals.

Lars Renström, president and ceo of the Alfa Laval Group, outlined his thoughts on the new acquisition: "The acquisition of Niagara Blower brings in new and complementary heat-transfer products, mainly air-cooled heat exchangers, which further strengthen our offering to the oil and gas processing industries.

"They strengthen our US portfolio and will gradually also be added to our product offering on a global scale."

NBCo is located in Buffalo, New York, and has 120 employees. It generated sales of about SEK425million (EUR49million) in 2012.

The intention is to integrate NBCo into the energy and environment segment within Alfa Laval's process technology division.

Meanwhile, due to what the company describes as unprecedented demand, Tranter says its Quick Ship programme is being expanded.

Customers will now be able to place an order from a wider selection of plate heat exchangers and have their new unit shipped from the Texas facility within three days.

Rapid response

The three-day Quick Ship programme provides rapid response to customer needs and results in process up time in no time - another example says Tranter of its continual focus on providing the best in class customer experience.

Designed to fulfil small and medium sized plate heat exchanger needs, Tranter has dedicated staff working expanded shipping hours to meet demand and quickly deliver throughout the USA.

Quick Ship models typically have the following design features: sizes from 2-in to 6-in ports; design pressure 100-150 PSI; plate materials 316ss and 304ss available in most models; plate thickness 0.4-0.6mm; gasket materials nitrile butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM) rubber; and connections in either studded port (4-in and 6-in), or threaded (2-in).

Allied heat transfer system analysis upgrade

Allied Heat Transfer has expanded its ability to analyse heat exchangers and cooling systems while the equipment is still in service - providing significant benefits for its customers.

The company uses a variety of test equipment to map the actual operating conditions of an installation, and Heat Transfer Research (HTRI) software for the analysis. HTRI is an internationally recognised method of performing these types of analyses. Allied can then provide an accurate report on how a particular unit is performing - and why.

Modifications to existing exchangers or coolers that may be derived from such analyses can be undertaken at the company's own workshop in order to produce higher performance and service reliability. Changes made can be verified by performing follow up tests on site. Further to this, air cooled heat exchanger performance can be simulated in-house on Allied's air cooled heat exchanger test unit which provides accurate performance results from tests of scale model versions of existing equipment. By fitting a scale model to the test unit, the company can simulate various scenarios and report on the measured performance of the exchanger with changes to air flow, fluid flow, construction types, operating temperatures and more.

Allied Heat Transfer operates a quality management system accredited by Det Norske Veritas and is an accredited NATA test facility for pressure vessels. In addition to the quality and mechanical testing systems, the company operates to stringent health, safety and environmental policies.

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