Cogeneration plants involve different applications for heat exchangers, as they allow to further increase the efficiency of the process. The use of heat exhangers in cogeneration starts from the pre-treatment of the biogas, an operation aimed at eliminating the impurities and humidity present in the biofuel to preserve the engine, up to the heat recovery from the exhaust fumes of the engine itself using shell and tube exchangers, maximizing the amount of thermal energy that the system can generate.

In this case, the Tempco exchangers work both on the jackets, with a brazed plate exchanger, and on heat recovery from exhaust fumes, with a shell and tube exchanger.

After 11 years of work, the customer then called us requiring a replacement of the gaskets on the flanges, which had worn out over time. At the time of installation, Tempco had supplied the exchangers, while the customer preferred to rely on another supplier for the gaskets, although to be fair, these are anyway components subject to wear and therefore requiring maintenance.

Overall, we can say that we are very satisfied with the successful application realized for this customer.

L'articolo Exchangers in cogeneration plant operating for over ten years proviene da Tempco Blog.

Also in 2023 we have installed a fair number of biogas plants, all equipped complete with chiller, heat exchanger and condensate separator.

All systems are always supplied in full configuration and are delivered ready for installation. Speaking about biogas, of particular interest are therefore the latest applications in the paper mill sector, with the aim of reducing polluting emissions. In fact, paper mills have a high potential for the production of biogas and biomethane, as the production cycle of a paper mill generates large amounts of waste water rich in biodegradable COD (chemical oxygen demand), which lends itself to being treated and valorised for the production of biogas.

L'articolo Chillers, exchangers and separators for biogas treatment proviene da Tempco Blog.

Following the previous infographics that spanned through automation, smart manufacturing in industrial processes and the renewables, finally heat recovery applications in the field of industrial production processes is what really characterizes Tempco’s engineering commitment.

The primary technology here analyzed for energy recovery are heat exchangers, a kind of thermal machines employing the physical effect of thermal transfer between two fluids having a temperature’s gap, allowing an intelligent re-use of thermal energy which is a very abundant form of energy available in a wide variety of industries, that can be re-used as second-level kind of energy in other points of the production process. With no further power consumption required, contributing to increase the energy balance of the process by implementing energy saving and efficiency solutions reducing CO2 emissions and the environmental impact of industrial productions.

A look at other technologies such as dry cooling and cogeneration is included as well, solutions that enable a more efficient and smart use of fuels, reducing energy waste for an increased and more efficient use and deployment of primary resources in cooling and heating tasks involved in any kind on industry, from oil & gas and steel mill to food & beverages and plastics, to chemical and pharmaceutical sectors. The key words of Tempco’s vision for each one of these sectors are energy efficiency and thermal energy recovery.

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L'articolo Infographic from heat to value, energy recovery in industrial processes proviene da Tempco Blog.

The challenges of the climate change force the industry to find ways to empower sustainability for a responsible development, respectful of the environment. Energy is a central element in the climate strategy for every industrial sector, starting with the way energy is employed. Energy consumption must be more and more intelligent and efficient, reducing the amount of energy required by industrial production in every application field. Tempco is committed to deploy thermal energy recovery solutions and to increase energy efficiency in cooling, heating and thermoregulating applications in industrial processes.

But energy saving is not enough: at the beginning of the value chain of power generation, the kind itself of energy which is produced and consumed must change. Power generation from renewable sources must increase, in order to reduce and substitute fossil fuels which are the cause of greenhouse gas emissions. Tempco also supports the renewables market by designing and engineering solutions for thermal energy management and production efficiency.

Indeed, an effective sustainable growth is strictly depending on the increase of renewables in the global energy mix, including hydroelectric, solar, wind and bioenergy. Renewables are in fact the unique key for the success of current trends such as mobility electrification and energy efficiency in industrial processes.

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L'articolo New Tempco Infographics, renewables for energy engineering proviene da Tempco Blog.

Biogas is a natural fuel, but in order to be employed in cogeneration plants it requires a special dehumidification treatment. This is achieved using systems composed by a chiller and shell and tube exchangers, especially engineered for this kind of application, which cool and dehumidify the biogas using a very cold mix of water and glicol.

In fact, biogas coming from digesters enters the system at temperatures of 35-40° C, and must be cooled at temperatures of approx. 4-5° C, eliminating the maximum possible amount of humidity contained. At this purpose, chillers at very low temperatures are employed, near the freezing point, at +1° C or +2° C.

On the outlet of the exchangers the biogas will then have a relative humidity of 100%, but with an extremely low absolute content of humidity. Installed on the outlet of the exchangers there are also condense separators, big tanks aimed to collect the condenses. Furthermore, on the output of the systems there are also additional filters, providing a further filtration of the biogas, which then is finally ready to enter the engines.

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L'articolo Shell and tube exchangers in biogas treatment for cogeneration proviene da Tempco Blog.

But there are also machines with lower power capacities on the market, allowing to operate both in conditioning and production processes applications, being able to reach temperatures of -10° C.

Those are machines produced by Robur, and Italian company that acquired many years ago the patent of this technology from an American company. These are in fact small size absorption refrigerators. The standard range of these machines employs a direct fired burner which provides the heat required to trigger the thermal cycle for cold production.

A very interesting and smart idea that fascinated me is to leverage waste heat coming from industrial production to start that same thermal cycle. The company has in fact modified its machines to integrate a sort of heat exchanger, which allows to work using waste heat coming from industrial processes, waste steam or diathermic oil at the end of a process.

The interesting thing is the extension of an energy recovery approach for the production of cold, leveraging energy that otherwise should be lost and dissipated.
The only limit I see here is that this application requires waste heat at very high temperature levels, between 190° C and 220° C. And it’s not easy to find waste heat at this temperature, but in case it is available the solution becomes surely extremely interesting and intriguing.

I’m thinking about applications where there is a continuous generation of waste heat, allowing the continuous production of cold. A kind of solution that could then be very interesting in a wide variety of applications, such as on waste fumes from cogeneration plants, or fumes coming from steel industries of metallurgy plants, where high amounts of high quality energy is available, meaning high temperature waste heat.

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L'articolo Waste heat to power refrigeration proviene da Tempco Blog.

Thermal energy is a very common presence in industrial production. Heat is indeed required in a number of production processes in industries such as food, industrial, textile, glass and ceramic industry, chemical, oil & gas and metallurgy.

Many among these industrial processes involve waste materials, and thermal energy is one that gets often lost at the end of the process. This is usually referred to as waste heat, and it can be present in several forms: fumes coming from furnaces combustion, or from internal combustion engines, turbine’s or cogenerators exhausts, steam coming from heat treatment plants or from drying tasks, just to name a few.

Within these same production processes, in a different step of the production line, a cooling system is then often required, also employing thermal energy but with a negative value, meaning a need for thermal cooling.

All these cases are suitable for the application of equipments that enable to employ that same waste heat to obtain chilling power, without further expenses in terms of primary energy consumes, by mean of heat recovery of the waste energy.

Waste heat can be divided in three classes: high energy, exceeding 650° C, mid temperature, between 225° C and 650° C, and low temperature, up to 225° C.

High and mid temperature waste heat are the most useful and ‘precious’, because they can be employed both directly or to feed further machinery such as cogenerators (combined production of heat and power) and absorbers, aimed to the production of chilling power. Low temperature waste heat can thus be employed in the form of hot air or water for heating purposes or pre-heating of further production processes that require low temperatures.

Cold production from mid-high temperature waste heat
The essential components of a machinery for cold production from waste heat are basically:

– waste heat at temperature higher than 220°C, with a proper flow rate
– heat exchangers, to achieve the thermal transfer from waste heat (such as exhaust fumes of a furnace) to a thermal fluid (diathermic oil or pressurized water)
– a circulating circuit for the distribution of the thermal transfer fluid to the absorber
– an indirect fired absorber for cold production

The overall system only require additional power for the operations of accessory equipments, such as circulating pumps and fans.

Power Fluid absorber units by Robur
Robur Power Fluid absorber units are an example of efficient thermal machines that allow to ‘produce cold’ leveraging the thermal heat coming from a technological process. The working cycle of the units is showed in this scheme.

The thermodynamic cycle employs a solution of water and ammonia, in a hermetic closed circuit that avoids refill, substitution and disposal operations. The thermodynamic cycle is triggered by the waste heat flow, heating the generator by mean of a coil, in which diathermic oil or pressurized water are flowing.

Condensation happens in air, without the need of a cooling tower, thus avoiding the related hydraulic circuit and control devices.

These units enable to produce cold water to be employed for air conditioning, production processes cooling or even for food preservation, being able to supply cold or chilled water down to -10° C.

Advantages of Power Fluid units
Each industrial process involving the presence of waste heat above 200° C and the need of chilling power can benefit from these absorber units, such as metallurgy industry, chemical, glass or cement industry, agrifood and dairy, achieving high energy savings and maximizing the efficiency of the overall production process.

Further advantages offered by Power Fluid units are:

– easy engineering and installation of the plant, not requiring cooling towers and suitable for outdoor installment, with small footprint
– high reliability, thanks to an almost static refrigeration cycle (only two moving parts are employed, including fans) ensuring long life span without efficiency decrease
– wide operating range, in terms of both external air (condensation) and outlet cold water, which can be supplied even at low temperatures of -10° C
– no particular permissions nor authorizations are required, since refrigerants are not employed, replaced by the use of ammonia, a totally natural and eco-friendly refrigerant (near zero ODP and GWP values)
– economically convenient, especially if the unit can be used for many hours/year, being that the chilling power obtained is actually for free

Preliminary feasibility conditions of the recovery plant
Some conditions must finally be verified for a first evaluation of the solution:

– Availability of waste heat at temperatures higher than 220-240° C. This is a mandatory condition to obtain a sufficient transfer fluid able to feed the absorber and effectively trigger the thermodynamic cycle

– concomitant presence of heat recovery and need of chilling power. The cooling energy supplied by the absorber is always subjected to the presence of waste heat to feed it. When chilling power production exceeds the cooling need it is also possible to store it, but it involves higher investments in the chiller circuit to be carefully evaluated
– Estimation of operating hours/chilling power required in order to calculate the ROI. The overall amount of chilling power produced will cover the costs of the plant, so that the higher the indicator is, the shorter will be the ROI.

L'articolo Absorption chillers, free and green refrigeration power from waste heat proviene da Tempco Blog.

The BPHE are available with two formats, with maximum number of plates of 120, available with different combinations of plate pattern, H, L or M.

The application fields are various, starting with HVAC systems and cooling and heating in industrial processes, such as machining centers and machine tools and plastic injection and extrusion systems. Especially interesting are the applications in the field of renewable energy, for example in gear boxes and hydraulic units in wind power generation and as evaporator, condenser and heat recovery in cogeneration and ORC plants. But also in transportation, not only for motor oil cooling in engine systems but also in battery cooling systems in electric vehicles, cars or buses.

L'articolo Brazed plate for renewables and electric vehicles proviene da Tempco Blog.

We have here a very virtuous production chain, an example of what is called circular economy, recovering wastes to obtain power generation. Shell and tube heat exchangers are the suitable choice for biogas cogeneration applications. Previous to the proper combustion cycle, the biogas must be treated in order to eliminate all the polluting elements that it gathers and also to extract all the humidity contained, which in case of combustion can damage the engines irremediably.

Biogas treatment include a part of thermal treatment for the dehumidification of these gases, which are usually at the temperature of approx. 34-40° C. The biogas is cooled down using a chiller working at very low temperatures, about 0° C, combined with a shell and tube exchanger with the cold fluid (water and antifreeze) flowing inside the shell. The biogas flows inside the tubes. The tubes are usually straight and sliding to facilitate cleaning operations from deposits that the gas can gather, but also to drain all the water condensed in contact with the cold flow of the glycol water. The condense must drain perfectly and get collected in a condense separator on the outlet of the exchanger.

The application usually requires long exchangers, in order to allow the biogas to flow inside the tubes as long as needed to ensure the complete elimination of all the humidity. Dedicated blowers send then the dehumidified biogas to the engine, and sometimes it can also be post-heated to obtain a proper combustion temperature.

Construction materials are usually carbon steel for the shell, without expansion joints due to the short temperature gap involved. Headers can be as well made of carbon steel, while the tubes can be made of copper. In case the biogas presents high levels of aggressive and corrosive elements, both headers and tubes must have a full stainless steel construction.

The tubes are pressed and, my personal choice, welded, in order to avoid any risk of leaks of glycol water from the shell inside the biogas flowing in the tube section.

L'articolo Biogas dehumidification for cogeneration proviene da Tempco Blog.

A cogeneration plant is usually equipped with an endothermic engine driving a generator to produce electricity. Cogeneration stands for power and heat generation at the same time, also leveraging thermal energy produced by the engine. This is possible thanks to heat recovery achieved by a shell and tube heat exchanger on the exhaust fumes circuit.

Exhaust coming as waste from the endothermic engine in cogeneration have very high amounts of energy, making thermal recovery really advantageous instead of dissipating the heat. Here exhaust are at very high temperatures, typically between up to 550 and 650° C depending on the kind of engine and fuel employed.

For cogeneration heat recovery applications, shell and tube heat exchangers are suitable with straight pipes to allow cleaning operations, because exhaust can contain particles from combustion requiring some periodical cleaning maintenance. Construction material is usually stainless steel, especially for pipes and headers being in direct contact with exhausts. Diesel oil, biogas and methane exhaust can indeed contain acid elements exposing the components to corrosion, an even higher risk in case of high temperature conditions of cogeneration plants.

Working with high temperatures, heat recovery cogeneration applications thus also require special construction tricks: aimed to avoid failures due to thermal expansion, with unwanted side effects such as leaks, all the tubes are welded and pressed on headers, while the shell, which allows water flow employed for thermal recovery, is equipped with a thermal expansion joint to compensate the expansion gap between the shell, with water at temperature of approximately 90°, and the tube.

L'articolo Exhaust heat recovery in cogeneration with shell and tube exchangers proviene da Tempco Blog.