This section describes five energy-saving applications that use plate heat exchangers, as well as examples of how they can be combined to save energy.

How much is the cost of energy ?

How to know the amount of annual benefit when recovering

the heat as a hot water, 30m³/h and 50°C heated up (20°C -> 70°C).

1. 1. In Fig.1, find the cross point between horizontal line extending from 50°C and flow rate curve of 50m³/h (green curve).
2. 2. Extend the line further down from the cross point, you can see the value 1,750kW on horizontal axis "Recovered Heat (kW)".
3. 3. Extend the line down to the 3k line (purple line) in Figure 2, you will find a monthly energy saving 12,500,000JPY/month on vertical axis "Energy Saving".

Chemical Industry

Bleaching application for Kraft Pulp

Process overview

There are two processes: heating the ClO₂ aqueous solution with steam and cooling the water supplied to the chiller unit with electricity.

Improvement effect

Water supplied to the chiller unit is cooled by the ClO₂ aqueous solution from the ClO₂ tank, and therefore heat can be recovered. ClO₂ aqueous solution that is heated with steam can be heated with hot water recovered from white liquor.
The power consumption of the chiller unit is reduced and heated steam is not required.

Multiple effect column evaporator

Process overview

This is a standard triple effective evaporation column, which is traditional and well-known process to reduce the steam consumption to approximately 1/3 from single column. Process is almost perfect, but something are still hidden.

Improvement effect

The wasted vapor temperature from the 3^rd column is so low that is usually ignored. But PHE is still applicable of its high efficiency. In this case, wasted vapor is used for pre-heating of the process feed. Additionally, new heat recovery network can be created by the infinity loop principle.

CO₂ Recovery

Process overview

In this process, the low-temperature lean amine in the absorption column absorbs CO₂ gas and becomes rich amine. This rich amine is heated, CO₂ gas is released from the regeneration column, and it becomes lean amine. It is then cooled and returns to the absorption column, and the CO₂ absorption/emission cycle is repeated.

Improvement effect

High-temperature lean amine from the regeneration column is cooled and sent to the absorption column. Low-temperature rich amine from the absorption column is heated and sent to the regeneration column. By exchanging heat between high-temperature lean amine and low-temperature rich amine, the amount of steam in the regeneration column can be reduced.