Why improving energy efficiency in thermal applications

Most industrial activities use thermal processes for production, thanks to heat-carrying fluids such as water, saturated steam, air, etc. This implies the adoption of a great number of generation systems, from common boilers to industrial steam generators up to large combustion plants. It is mandatory to guarantee the efficiency of this kind of utilities, in order to reduce the fuel consumption for the same output quantity.

RENOVIS proposes several solutions to improve the thermal efficiency of its own plants.

IMPROVING THE EFFICIENCY OF EXISTING PLANTS

Boilers and steam generators normally used by companies are often outdated, so they can be technically improved. Over the years, technical progress has led to more and more efficient equipment able to guarantee less fuel consumption for the same level of performance.

Mainly, there are two kinds of possible actions:

• replacing the currently used boilers with more efficient equipment
• improving the efficiency of the existing boilers.

Improving the efficiency of a boiler means adopting technical solutions that allow to raise the quality of the combustion thus increasing the thermal performance. RENOVIS is able to meet your efficiency goal.

WASTE HEAT RECOVERY

Talking about thermal energy consumption is not entirely correct. Energy cannot be created nor destroyed, but it transforms into other forms of energy. In industrial thermal processes, the energy associated to the fuel supplied to the boilers transforms into the sum of two components: a useful quota, used to heat the process fluid (air, water, steam, etc.) and a “waste” quota, associated to combustion fumes (and other waste, if present) usually dispersed in the environment.

This waste often presents thermodynamic characteristics (especially temperature) that make it still usable in other thermal processes inside the factory.

RENOVIS is able to recover the thermal energy associated to process waste, saving a great amount of fuel and thus giving an economic advantage. There are several possibilities to recover waste heat: it is possible, for example, to recover heat from the gas expelled into the atmosphere by industrial ovens or textile finishing machines, and use it to heat up process or heat-carrying fluids.

In case of industrial processes that imply the disposal of a great amount of hot water, either very dirty or contaminated (for example, in fabric dyeing, paper industry, leather tanning of food industry) it is possible to install proper heat recovery systems. Nowadays, technology allows to achieve a triple advantage of recovering thermal energy (normally lost) that can be reused in the industrial process, purifying the effluents of most solid pollutants (e.g. fibers) and levelling the effluent temperature before treatment and subsequent disposal through sewage network, thus complying to the goals and limits imposed by law. In addition, it is possible to exploit the recovered heat to evaporate (without cost) the liquid part of pollutants whose disposal is often very expensive.

HEAT RECOVERY ON COMPRESSORS

Part of the electrical energy consumed by a regular industrial compressor turns into heat during compression, due to the thermodynamic irreversibility of such process. A fraction of that heat can be recovered. There are two main methods of recovering heat, which can be used on screw compressors:

• heat recovery through the cooling air coming from the compressors;
• heat recovery from the oil lubrication circuit of the compressor.

In the first case, the heat generated by the electric motor, the oil radiator and the chiller comes out of the compressor through the cooling airflow. The latter can be reused directly to heat up environments or production facilities. In the second case, the heat generated by the compressor is recovered by the lubrication circuit through an oil/water heat exchanger. This way, it is possible to heat up a water flow (for heating or sanitary use) up to 70°C.