Heat recovery

What is industrial heat recovery?

In many industrial processes, significant amounts of heat are generated as a byproduct. Industrial heat recovery is the process of capturing and reusing the heat generated by all kinds of industrial equipment – including vacuum pumps and compressors – to improve energy efficiency and reduce operating costs.

This practice is particularly beneficial in environments where machines are in continuous use, as this can produce substantial amounts of heat. This heat can be recovered and repurposed for various applications. By implementing heat recovery systems, industries can not only reduce their energy consumption but also enhance the overall sustainability of their operations.

Heat recovery from vacuum pumps

All types of industrial equipment produce heat during operation, including vacuum pumps. As a vacuum pump compresses gas, it generates a small amount of heat. The higher a vacuum pump’s efficiency, the less it creates. A cooling system manages any excess. Typical systems include air cooling using the ambient air, or water cooling via either an open or closed-loop circuit. Without a heat recovery system, the heat dissipates via the cooling system, and the energy is effectively lost.

A heat recovery process for a vacuum pump works by capturing the heat energy using a heat exchanger connected to the vacuum pump’s cooling system. The heat exchanger transfers the thermal energy emitted from the vacuum pump to a heat transfer medium, such as water. Heat exchangers use fluids to transfer heat because fluids have high heat transfer coefficients, which makes them efficient at absorbing and releasing heat.

As well as the fluid, the design of the heat exchanger also plays a role in efficient heat transfer. Heat exchangers are designed in such a way that the two fluids are constantly in a position where they can exchange their heat. This maximizes the surface area through which heat transfer can occur. There are a number of different designs, each with varying levels of efficiency. The simplest design is the double-pipe heat exchanger. All other heat exchangers, however complex, operate on the same principle.

The process begins with the hot fluid, either the gases or the cooling liquid, flowing through one set of channels or tubes within the heat exchanger. At the same time, a colder fluid, such as cooling water or air, flows through an adjacent set of channels or tubes. The heat from the hot fluid is transferred through the walls of the heat exchanger to the cooler fluid. This is achieved through conduction, where thermal energy moves from the hotter medium to the cooler one. The walls are therefore made of materials that offer very high thermal conductivity, such as copper and aluminum.

This newly heated fluid can then be used for various industrial processes that would otherwise require their own energy for heating, such as preheating feedwater in a boiler, heating buildings, or drying processes. In some cases, the excess heat can even be directly reused in the vacuum process, such as hot water for distillation, or heat for thermoforming machines.

The Benefits of Heat Recovery

Better working environment

In a typical set-up where heat is allowed to dissipate into the ambient air, the area surrounding the vacuum pump will heat up. While in modern, efficient vacuum pumps, this amount is minimal, older vacuum pumps can generate more heat as parts wear down. This can drive the need for additional cooling for heat-sensitive processes. One kilowatt of additional cooling energy is required for three kilowatts of waste heat from the vacuum pump. As a result, energy costs rise. A heat recovery system captures this heat and diverts it to an area where it can be used productively, instead of losing it to the production floor. There it would warm the production environment and increase the demand for air conditioning.

Heat recovery for energy efficiency

Heat recovery systems significantly improve energy efficiency by capturing and repurposing waste heat. This process reduces the overall energy consumption of industrial operations. Firstly, the net energy required for the initial application is lowered, as the energy that went towards generating heat is ultimately recaptured. Secondly, when the heat is reused, further energy costs are saved. The process that uses the recycled heat no longer needs as much energy to generate heat from scratch. In some cases, the requirement for additional energy input can be eliminated entirely. This can result in enormous cost savings.

Environmental impact of heat recovery

As energy consumption drops, the environmental impact of the process also decreases. By reducing the need for – and dependence on – external energy sources, heat recovery can contribute to reducing the carbon footprint of the whole process. Such a system can entirely replace a fossil-fuel-powered heater, completely eliminating its emissions of carbon dioxide and other environmentally harmful pollutants.

Our solutions for heat recovery processes

Every industry is different and has its own requirements for a heat recovery system, therefore there is no one-size-fits-all approach. Experienced Busch specialists will work closely together with you to design vacuum and overpressure systems that match your specific heat recovery requirements.

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