Page 50 - Impiantistica industriale

NEW TECHNOLOGIES

Feed/Product/bioproduct Quantity per year U.m. whenever a CO2 capture is required. The high partial pres-
Waste feedstock 192.000 Ton/y sure of CO2 in the cooled syngas fed to PSA allows a less
Hydrogen production 200 MNm3/y energy intensive capture once compared to CO2 capture
performed on hot flue gas. Case study here analyzed will be
Granulated 34.000 t/y
based on a plant architecture without CO2 capture.
Sludge 7520 t/y In the proposed architecture three gasification lines are
Utilities Quantity per year U.m. adopted with an overall capacity of about 192.000 ton/y of
Electric Power 84000 MWh/y waste delivering around 200 MNm3/y of Hydrogen.
Heat and material balance around the proposed scheme
Industrial water 50.400 m /y have been performed through Aspen Plus Process sim-
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Demi water 130.000 m /y ulator. Main results in terms of products and by-product
3
Natural Gas 12.176 ton/y production as well as utilities consumption are reported in
Table 4.
Instrument Air 10 MNm /y
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Nitrogen 11.5 MNm /y
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Oxygen 82.5 MNm /y 2.1 Evaluation of Hydrogen Cost
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Cooling water 40 Mm3/y of Production
Table 4 - Material balance for the waste to H2 scheme In order to assess the economic feasibility of the waste to
hydrogen technology, an economical evaluation has been
M€ carried out based on CApital EXpenditures (CAPEX) and
CAPEX ISBL 190 OPerating EXpenditures (OPEX) estimation.
CAPEX OSBL 30 The overall CAPEX has been estimated into around 242
Contingency (10%) 22 M€. Relevant breakdown is reported in Table 5.
TOTAL 242 In order to evaluate OPEX and related H2 cost of produc-
tion, the following assumptions in terms of specific cost of
Table 5 - CAPEX estimation for Waste to H2 plant
utilities has been adopted (Table 6).
On the basis of utilities consumption derived from heat and
Cost component Value material balance (Table 4), Opex has been estimated into
Waste treatment ton/year (three gasification lines) 192000 around 28M€/y with the breakdown shown in Figure 4.
Vitrified granulate produced ton/year 34000
Concentrated sludge produced ton/year 7500
Maintenance cost as % of the CAPEX 2%
Depreciation
Equity (20 year and 6% interest rate) 0.0872
Bank loan (12 year and 3% interest rate) 0.0672
Personnel (at company cost) M€ per year
7 people per shift (7x5) = 35 people 1.75
3 specialist all over the working day 0.24
1 Manager 0.12
RDF-Plastics price € per ton 150
Electric energy cost € per MWh 70
Natural gas price, € per Sm3 0.24
O2 cost, € per Nm3 0.078 Figure 4 - OPEX Waste to Hydrogen
N2 cost, € per Nm3 0.078
Instrument air, € per Nm3 0.028 The resulting COP is strictly related to the waste gate fee.
By varying the gate fee from 130€/ton up to 150 €/ton, the
Industrial water, € per m3 0.08
resulting hydrogen cost of production range from 0.102
Cooling water, € per m3 0.014 up to 0.083 €/Nm . These values are very promising and
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Demi water, € per m3 0.43 competitive with cop of production of conventional steam
Cost slag disposal € per ton 40 reforming process.
Cost concentrated slug disposal € per ton 200
2.2 Estimation of CO emission for
Table 6 - Assumption list for economic evaluation 2
the waste to hydrogen technology

The resulting syngas is cooled through heat recovery and For a better understanding of potential carbon footprint re-
final trim with cooling water, sent to a gal liquid separa- duction of the proposed Waste to Hydrogen technology, a
tor for the removal of condensate and routed to a PSA simplified LCA analysis has been performed.
unit. The latter allows to produce Hydrogen at purity in The use of waste as feedstock for chemical synthesis al-
order of 99.99% and a purge gas stream used as fuel in lows to fulfill at the same time two different services: from
the auxiliary boiler. A different approach may be adopted one side the recovery of waste and from the other the syn-

46 46 Impiantistica Italiana - Gennaio-Febbraio 2022