## 4 Conclusions  
In this paper, we have shown that dry nonconventional solids do not participate in heat exchange processes, so energy integration cannot be carried out with the feed stream. Likewise, wet nonconventional solids participate in the heat exchange processes, but this simulation is not realistic because, having a high moisture (90 wt.%), the phase is always solid even though the temperature is higher than the critical temperature of water, which is not true. However, if the wet nonconventional solid is simulated by a mixture of a dry nonconventional solid and a stream of liquid water, the feed stream partially participates in the heat exchange processes to the extent that water does; however, the solid fraction is not really heated. The overall energy balance does not vary if the decomposition of biomass is placed at the beginning or at the end of the system. However, if the solid is nonconventional and the decomposition is performed at the end, both the conversion and the temperature rise take place in the RYield, because the heat exchangers do nothing. If the biomass decomposition is carried out at the beginning (and the conversion took place at ambient temperature), sensible heat can be used (and saved) by a series of heat exchangers to raise the temperature from 25 to 800 \({}^{\circ}\)C (or whatever final temperature it was). Upon a base case study using a wet biomass of 10,000 kg/h with 90 wt.% water, where the SCWG reaction takes place at 240 bar and 800 \({}^{\circ}\)C, if the temperature at the SCWG reactor inlet increases from 350 \({}^{\circ}\)C to 400 \({}^{\circ}\)C, the heat exchange increases by 57% from 4 MW and by 34% if the water content decreases to 70 wt.%, although more heat relative to the solid is saved. Thus, a practical approach is proposed for applying heat integration for the supercritical water gasification (SCWG) of solid biomass under chemical equilibrium as an alternative to the current method found in the literature. In the new approach, the biomass is decomposed into conventional compounds at ambient temperature, so only enthalpy formation is considered in its energy balance, and the stream leaving can be really pumped and heated to the temperature at the reactor inlet. In this way, sensitive heat can be exchanged by a train of heat exchangers, thus saving energy in the process by energy and material  
Figure 7: Sensitivity analysis for the thermal power (heat load) of the SCWG of orange peel for ARR-6 at different concentrations (wt.%) and temperatures (\({}^{\circ}\)C); (concentration@temperature). Note: These numbers in the bottom table correspond to the thermal power represented on the ordinate axis. Therefore, the unit is kW for all of them. integration. This approach may be applied considering the stream entering the SCWG reactor operating under chemical equilibrium. Two possibilities or routes are proposed depending on how the decomposition is made: (1) following the typical decomposition into a solid phase (carbon, ash, and sulfur) and a gas phase (water and diatomic molecules of H\({}_{2}\), N\({}_{2}\), O\({}_{2}\), and Cl\({}_{2}\)), or (2) into a set of molecular compounds representative of biomass if the chemical composition is available. This novel method is helpful for evaluating processes under research and development using simulation and can be used for any thermochemical process other than the SCWG of biomass, where the amount of sensitive heat to be exchanged is likely much higher because of the lower amount of water. The results can be explained using the fundamental physicochemical principles, i.e., thermodynamics, mass and energy balances, and chemical equilibrium, so energy and exergy efficiencies can be assessed with confidence. The application of this approach would affect the use and design of heat exchangers to be placed for feed preheating before entering the SCWG reactor or any other reactor in a thermochemical process of biomass. F.J.G.O.