Municipal Waste

Replacing a wet scrubber by a dry injection finishing process

The challenge

The customer, a Belgian Energy from Waste plant, decided to modernise its site with the key objective of reducing acid gas emissions to half the regulatory levels (i.e. 5mg HCl/Nm3 and 25mg SO2/Nm3).

Download full Case Study (PDF - 441 Ko)

Optimising the semi-wet process

Background

The operator of an energy recovery plant for household waste in the North of France has requested Lhoist’s services in the improvement of their semi-wet process. The plant contains two lines at a capacity of 8t/h, originally equipped with a semi-wet treatment system:

• Furnace 1: electrostatic precipitator, reactor with milk of lime atomiser followed by a bag fi lter.
• Furnace 2: reactor-atomiser and electrostatic precipitator.

Improvements

The first stage involved replacing the hydrated lime with (Sorbacal® Q) quicklime for the preparation of the milk of lime to be injected into the atomiser. In the second stage, the additional dry injection of Sorbacal® SP allowed improved performance and new quality standards. The capture results in the table below were obtained with the average consumption of 14kg, the equivalent of Ca(OH)2 per tonne of household waste; 75% of the separation was done via milk of lime in the semi-wet and 25% via dry injection of Sorbacal® SP.

Download full Case Study (PDF - 253 Ko)

Developing the semi-wet process

Improvement and optimisation

Context

The plant in question is an energy recovery plant for household waste with three incineration lines at a capacity of 14.5 t/h. Each line is equipped with semiwet processes powered by milk of lime prepared directly from quicklime- Sorbacal® Q.

Both the milk of lime lines and the atomisers were encountering frequent blockages which caused unforeseen stoppages and repeated maintenance. As such, the process was on frequent shutdown and its compliance with existing European legislation was at risk.

Download full Case Study (PDF - 389 Ko)