Heat Recovery
“The cost-effective reduction in energy demand through recovering waste heat has always been a goal of process industries. Nthalpy’s revolutionary technology, combined with intelligent application engineering, provides a key component to achieving this.”
High temperature heat pumps
Virtually every industrial process will emit energy in the form of waste heat during its operation. In most cases this energy is not recovered due to an unacceptable financial payback. Challenges to achieving viable payback are predominantly governed by technical factors such as the temperature of the waste heat or the absence of a suitable user near to the heat source, without which long and expensive distribution pipework is required. Solving these issues has been the goal for Nthalpy and one answer is its high temperature heat pump, which can recover waste heat from as low as 60°C and convert it into a high temperature heat source up to 200°C.
All solutions can have the option to generate the recovered heat as steam, pressurised hot water, or into a thermal fluid. Being able to convert the waste heat into steam allows the recovered energy to be distributed at the lower cost of utilising smaller-bore steam pipes, or injected back into the site’s existing thermal distribution network, thus saving all distribution costs. On many systems, such as distillation columns, spray dryers, flue gases and ovens, this energy can be used back within the process to drive the thermal cycle, thus closing the energy loop.
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Solutions such as these can save up to 85% of the existing energy costs.
Application Examples
Distillation vapour recovery
Many processes require the separation of solutions through distillation. Continuous distillation systems often recover a small percentage of the condensing heat to preheat the feed solution, but the remaining heat is rejected into cooling water systems and removed through cooling towers.
Utilising an indirect heat pump, Nthalpy is able to recover over 90% of this heat to not only preheat the feed solution, but also provide the energy required to boil the solution within the re-boiler. Energy savings on these systems, (net of any energy required to drive the heat pump), can provide cost savings of over 50% against current operating conditions.
Flue gas energy recovery
Many systems are available to recover heat from hot flues and chimney stacks, however without a local use for the heat or an economical method of ‘transporting’ it, these systems are not justifiable. Utilising Nthalpy’s heat pump to recover this heat and to generate steam can solve this problem.
Steam has a very high energy density and therefore requires only small, relatively cheap pipework to be installed to the final user. Alternatively, if a steam infrastructure already exists then this steam can be injected into it. Both options reduce the total solution costs and improve system payback.
Steam and Vapour Recovery Systems
Due to steam’s high energy density, the latent energy contained in steam vapour is very high and the recovery of this energy within the vapour phase is very efficient. Steam vapour can be generated from many sources, such as flash vessels found in nearly all steam processes; driers within the food, paper and cement industries; kettles, such as those found in breweries; and free-steaming systems used for sterilisation within pharmaceutical and sterile processes.
Anywhere where the process releases steam vapour it is releasing considerable amounts of energy. Nthalpy can recover these wasted energy steams either directly, or indirectly if the process needs fresh steam to be generated at the boosted pressure to drive the main process or any other process within the factory.
