Covanta WtE case study

 Waste to Energy – LimeCure 50
Covanta are one of the largest operators of Waste to Energy plants in the world. With
over 40 plants processing 17m tonne pa of waste they are the largest player in the US
with over 65% of the US waste to energy market. The company has the highest of
environmental standards so they were keen to trial LimeCure in their plants.
The Covanta Lancaster Plant
The Lancaster County Resource
Recovery Facility is located on the
banks for the Susquehanna River in
Pennsylvania and processes 1,200
tons per day of solid waste in three
units. The facility generates 35.7 MW
of renewable energy.
The gas cleaning systems include a semi-dry lime slurry gas scrubber with a fabric filter
baghouse, SNCR and activated carbon. The system is controlled and monitored
continuously. Covanta plants consistently operate at under 25% of the consented limits
required by the Clean Air Act.
The plant uses around 26lb lime/ton of waste to scrub the gases (13kg/tonne). The burnt
lime is slaked on site and sprayed into the exit gas absorbers. Annually the plant
consumes 400,000 tpa of waste and around 4700 tonne per annum of burnt lime before
the introduction of LimeCure.
Lancaster operates a batch stirred tank detention slaker operating at 180 oF or 80 oC.
Burnt lime (CaO) is slaked with water to produce a 22% calcium hydroxide slurry for the
spray absorbers.
Covanta case study
V1
April 2015
Waste to Energy – LimeCure 50
The Trial Results
In Q1 2015 Covanta carried out a trial with LimeCure from Applied Specialties Inc to
demonstrating the advantages of LimeCure in increasing the slurry surface area,
reducing emissions and lime usage.
The LimeCure is automatically dosed at the required rate into the batching water before
the addition of the lime in the slakers.
The trial delivered a 38% reduction in lime usage per ton of waste from 26.3lb/ton to
16lb/ton. This will provide reductions of over 1700 tonne per annum of lime plus the
corresponding reductions in tonnage of ash for disposal.
Burnt Lime Usage per tonne of waste before and a5er the trial 30 25 38% reduc<on 20 15 lb lime / t waste 10 5 0 Before A-er Other advantages from the use of LimeCure have been:
1.
2.
3.
4.
Avoidance of acid washing of the slurry pipework
Metals content of the ash increased as did the density
pH of the ash dropped
quantity of baghouse ash reduced significantly along with disposal costs
The trial has been so conclusive Covanta are now in discussions about rolling out
LimeCure to all their plants in the USA with potential lime savings in excess of 25,000tpa.
For more information contact:
mike.eberlin@alkalisolutions.co.uk
07921498087; 01299 896825
www.alkalisolutions.co.uk
Covanta case study
V1
April 2015