Increased rates of heat transfer from latest heat exchangers

Paul Boughton

High heat transfer capacities, along with increased surface area, reduced fouling and ease of maintenance are the driving forces in heat exchanger technology development and use. Sean Ottewell reports.

In Turkey, HRS Heat Exchangers has supplied WABAG with a customised thermal transfer solution for use in a sewage treatment application in Siverek.

WABAG is one of the world’s leading suppliers and installers of water and wastewater treatment plants and the Siverek plant provides sewage treatment to residents throughout a region of south eastern Turkey.

At the plant, sewage sludge is treated in an anaerobic digester to breakdown the biodegradable material and produce methane gas. Once captured, the gas is used to power the plant, significantly reducing overall operational energy costs and improving site efficiencies. In addition, any additional supply of this renewable, green power can be fed into the local grid to provide wider benefit to the local community.

HRS says that its DTI heat exchangers are suitable for heating sludge in anaerobic digesters as the corrugated tubes provide an internal tube profile that inhibits fouling tendencies and increases the rate of heat transfer. Fouling or snagging of waste particles is prevented by having no change in cross-sectional area along the length of the heat exchanger and the increased turbulence from the corrugation improves heat transfer efficiency. This increased efficiency results in a shorter length to meet the required thermal duty offering a more compact and effective design with a smaller footprint.

The two DTI heat exchangers installed by WABAG are mounted on a common stainless steel clad frame and are used for digester heating. Both are thermally insulated. 

WABAG senior mechanical engineer Ersin Sagir explained the thinking behind the new technology: “WABAG are committed to investigating ways of increasing the efficiency of our installations and effectively reducing the carbon footprint of our customers. The new heat exchangers from HRS will help towards ensuring we optimise the Siverek plant efficiency."

Ming Lam, process design engineer with HRS added: "HRS has wide experience and expertise in areas of anaerobic digesters and the effective generation of renewable energy from waste. Our corrugated double tube heat exchangers are ideal for this application and offer proven treatment of waste streams with high thermal efficiency which increases plant profitability. As with all of our solutions, this system is specifically engineered to address customer requirements and deliver maximum optimisation of their plant processes."

In a separate development, HRS Heat Exchangers has a launched new rotary scraped surface heat exchanger. Known as the HRS Rotex, it is the latest innovation from the company’s product development centre in Lorquí, Spain.

The patent pending device is said by HRS to have a number of key features which make it stand out from other rotary scraped surface heat exchanger technologies.

For example, it combines a high heat transfer capacity with increased surface area. This, together with its helical screw, reduces pumping costs and makes it a good solution for highly viscous products. 

An added bonus, says the company, is ease of maintenance; designed into the product, this reduces operational costs and makes the HRS Rotex an ideal solution for both new projects and to replace existing equipment where energy savings and whole life costs are key in the decision making process.

Brazed plate heat exchangers

The brazed plate heat exchanger (BPHE) is one of the most efficient ways to transfer heat from one medium to another. A BPHE consists of corrugated plates combined to create complex channels through which a hot medium and a cold medium can be distributed. The media come into close proximity inside the BPHE without mixing on either side of the corrugated plate, and energy is transferred from one to the other as they flow side-by-side.

Using its AsyMatrix technology, SWEP's heat exchangers are designed to deliver maximum energy efficiency and system performance. 

The company’s new high-capacity B633 is built on its novel XXL platform, with six-inch ports and high plate numbers. It handles water flows up to 350m3/h with a pressure drop limited to 50kPa. 

This high flow capacity BPHE is suitable for a diversity of demanding applications, such as condenser and evaporator in power generation, engine oil cooler, steam condenser, heat recovery in chillers, or for specific district heating installations. 

The product offers plate heat exchanger-like capacities at high temperature and pressure, without the wear and tear of parts. Up to 95% of the material in BPHEs is used to transfer heat, as opposed to other technologies that use much of their material for support equipment, shell, or frames. This, says SWEP, allows users to benefit from savings on energy consumption, spare parts, space, transportation and installation. 

Another heat exchanger supplier, Alfa Laval, is to supply compact heat exchangers for AkzoNobel’s caustic evaporation plant in Rotterdam, the Netherlands. The order, which was won by the company’s new process technology division, is worth approximately SEK 120 million (€13 million), with deliveries scheduled for late 2014 and early 2015.

The compact heat exchangers will be used for concentrating caustic soda, an important ingredient in the chemical and petrochemical industries. They will re-use heat from different steps of the evaporation process, maximising energy efficiency and minimising energy use.

“This is Alfa Laval’s largest caustic installation to date and it will include our compact heat exchangers in a set-up that makes the process extremely energy efficient,” said Lars Renström, president and ceo of the Alfa Laval Group.

In business news, heat-transfer technology and engineering and design services specialist Luvata has moved into a new, larger facility at its heat exchanger manufacturing facility in Juarez, Mexico. It has double the space of the company’s existing facility, plus dedicated shipping and receiving docks.

“We were land-locked at our previous location. When the owners sold the building, it provided us with the opportunity to select a more modern facility that would better meet our manufacturing requirements,” explained Michael Flanders, vice president of Luvata Heat Transfers Solutions Americas. “We were able to design the interior and place the machines in a way so we can have an optimum flow. Capitalising on the natural lighting alone will significantly reduce our electricity consumption as well,” he concluded.

Triton fund buys GEA heat exchanger business

The Triton fund has agreed to buy GEA Group's heat exchangers business for approximately €1.3 billion. The business is an important global manufacturer of heat exchanger products and is particularly strong in Germany and Western Europe. 

GEA’s diversified product line and application portfolio includes wet and dry cooling systems and components and other project-type businesses. The company is based in Bochum, Germany and employs 7300 people worldwide. Its 2013 revenues were €1.5 billion.

“GEA Heat Exchangers operates in niche markets with global growth opportunities. Triton looks forward to supporting the management team in developing the company further as a standalone entity," said Peder Prahl, director of the general partner of the Triton funds.

"This transaction is an important milestone for us, enabling GEA to further focus on the food and beverage industries. We strongly believe that Triton is a highly reputed new owner who shall be able to assist the company through its growth journey,” added Jürg Oleas, ceo of GEA Group.

"GEA Heat Exchangers has a strong market position, and is well positioned and commercially successful thanks to its excellent product portfolio," explained Christoph Michel, ceo of GEA's heat exchanger business. "As an investor, Triton can offer a new perspective, enable us to leverage our growth potential and develop the company into an internationally important provider of heat exchange solutions. We are looking forward to accelerating our growth with the new owner on board."

Within Europe, the Triton fund focuses on companies involved in the industrial, business services and consumer/health sectors.