FHS-SEP23-PG28+29_Layout 1 11/09/2023 10:42 Page 28
RECYCLING & WASTE MANAGEMENT H
eat regeneration (or heat recovery) is the process whereby heat from a process which would otherwise be lost or wasted is recaptured and used for useful heating
purposes. Heat regeneration should not be confused with ‘regenerative heat exchangers,’ which are a specific type of heat exchanger in which the product and service fluids flow alternately and the heat is stored in the structure of the heat exchanger. At HRS when we talk about heat regeneration,
we mean the recovery of as much surplus heat (or cooling capacity) as possible after the primary function of the heat exchanger has been performed. This can then be reused to either improve the efficiency of heat exchange process or used elsewhere. ‘Recovery and re-use of industrial waste heat is an attractive concept that could simultaneously reduce energy costs
and CO2 emissions.’ Given the importance of energy efficiency in
reducing the use of fossil fuels and greenhouse gas (GHG) emissions, it can be argued that it is imperative to employ heat regeneration and recovery at every opportunity. As at least one paper has pointed out, ‘The use of excess heat could also be important to improve the economic and climate footprint feasibility of new processes… by avoiding the addition of new heat production capacity.’
BENEFITS OF HEAT REGENERATION Heat recovery improves the energy efficiency of heat exchange processes, so the greatest benefit of heat regeneration (recovery) is that less energy is required for a particular heating or cooling operation. This obviously provides financial benefits but is also better for the environment compared to systems without heat recovery. Repurposing recovered heat can also reduce the amount of heat required for certain processes. For example, if a material is pre- heated with recovered heat, then it may be possible to complete the necessary heating (for example for pasteurisation) using hot water from another source or part of the factory, instead of requiring a dedicated boiler to provide the necessary temperature rise. By increasing the energy efficiency of the
heat transfer process, heat recovery can also make it possible to reduce the size of the heat exchange equipment required or reduce the necessary processing time.
HEAT RECOVERY IN ACTION One example can be found in food pasteurisation processes, where products such as cream need to be heated to the necessary temperature to achieve pasteurisation, then rapidly cooled to maintain shelf life and quality. Such systems involve the use of two heat exchangers: one uses hot water to raise the temperature, while the second uses chilled water to cool the cream down again. The cooling process produces warm
RECAPTURE UNTAPPED ENERGY THROUGH WASTE HEAT REGENERATION
Water which has been heated by cooling food products can be used to pre-heat the same product ahead of pasteurisation, reducing the overall energy requirement
Many industrial processes require energy, but only a portion of that energy input is used for each operation such as pasteurisation or evaporation. Unused energy is wasted, often passing to the environment as hot gas or liquid. However, by using heat exchangers, it is possible to recapture most of this untapped energy through waste heat regeneration.
By Matt Hale, international sales and marketing director, HRS Heat Exchangers
water which can be discarded, cooled for re-use, or cooled with some of the heat contained being used to pre-heat the cream before the pasteurisation process. This last option utilises heat recovery or heat regeneration, reducing the amount of new energy required for the subsequent first heating phases. As another example, many biogas plants use
heat exchangers to pasteurise the digestate produced during the anaerobic digestion (AD) process. The ‘surplus’ heat which is generated after the system has been running can also be used to pre-heat the digestate, reducing total heat load and improving overall efficiency. Heat recovery can also be used in gaseous
HRS DCS Digestate Concentration System uses the steam produced by each evaporation cycle as the heating media for the next effect
applications. Whether it is using the heat from the flue gas of a biogas combined heat and power (CHP) engine to pre-heat digestate, or a
28 SEPTEMBER 2023 | FACTORY&HANDLINGSOLUTIONS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50
