HTB7 and HTB3 Molten Salt Heat Storage:
SOLAR SALTS:
1. By mixing these salts accordingly, the resulting eutectic melting point can be set to be in the range of solar and fossil fuel energy producing systems, so that they can be used to store required amounts of energy in insulated environments for suitable lengths of times.
2. The amount of energy and length of time for which it is stored will depend on the resulting heat storage characteristics of the resulting salt mixture as well as the heat insulating materials used to cover their containers.
3. Latent Heat: 113.01 J/g
60% NaNO3 + 40% KNO3, wt %),
Melting Point: 222.8°C
4. Latent Heat: 110.7J/g
Hitec(53% KNO3 + 7% NaNO3 + 40% NaNO2, wt %)
Melting Point: 142°C
5. Latent heat: 80J/g
Hitec XL(45% KNO3 + 7% NaNO3 + 48% Ca(NO 3) 2,
Melting Point: 120°C
6. Ammonium nitrate (NH4NO3)
Latent Heat Melting Point: 170°C
7. NaCl + NaOh
NaCl: 2165 kg/m³
NaOh: 1250 kg/m³
Specific Heat NaCl: 0.88 J/(g·°K)
Specific Heat NaOh: 1.488 kJ/(g.°K)
Mixing Weight Ratio: 1: 9
2.165kg/l
1.250kg/l
Latent Heat: 300J/g
Latent Heat: 300kJ/kg
Melting Temperature Range: 204°C to 331.9°. This is the African low price combination.
8. By looking at position [3], [4] and [5] above, it can be seen that an eutectic mixture consisting of those components allows a molten salt mixture for HTB7 and HTB3 to be made that has melting points as is required in order to move heat from:
- Burner exhaust to HTB7
- Turbine exhaust to HTB7
- HTB7 to HTB3
- HTB3 to Heat Storage (HS)
9. HTB7 and HTB3 are heat transfer buffers that only need to store heat for the time it takes to move that heat to the next component.
App. Diagram 3 - Collecting Heat for Reuse
Collecting Heat Using Vapor and Therminol
Information about the specific capabilities of a turbine is difficult to come by, unless one is actually in the process of buying one, therefore the following assumptions will be made:
Assumption 1:
A. Vapor temperature to Turbine = 227ºC
B. Temperature loss in Turbine = 50ºK
C. Vapor temperature from Turbine = 177ºC
D. Assume Burner exhaust temperature to HTB7 = 200ºC
E. Heat transfer Liquid around Burner exhaust:
Therminol
F. Heat Transfer Liquid in V14, JP, HTP2, V13 circuit:
Acetic Acid
4.1 bar @ 170ºC
7.8 bar @ 200ºC
G. Heat Transfer Liquid in V10, HTP1, Adj-V3, Adj-V4, Adj-V5 circuit:
Therminol
H. Heat Transfer Liquid in HCR-3, Exp-V3, Cmp-P4, V1, V2 circuit:
p-Xylene
3.4 bar @ 190ºC
7.1 bar @ 230ºC
Assumption 2:
A. Vapor temperature to Turbine = 227ºC
B. Temperature loss in Turbine = 70ºK
C. Vapor temperature from Turbine =
157ºC
D. Assume Burner exhaust temperature to HTB7 = 200ºC
E. Heat transfer Liquid around Burner exhaust:
Therminol
F. Heat Transfer Liquid in V14, JP, HTP2, V13 circuit:
1 Butanol
2.8 bar @ 150ºC
7.7 bar @ 190ºC
G. Heat Transfer Liquid in V10, HTP1, Adj-V3, Adj-V4, Adj-V5 circuit:
Therminol
H. Heat Transfer Liquid in HCR-3, Exp-V3, Cmp-P4, V1, V2 circuit:
p-Xylene
3.4 bar @ 190ºC
7.1 bar @ 230ºC
The capability of the heat transfer function must be such that it is able to transfer the amount of heat collected, so that during operation, heat being added to the molten salt can be removed, before the salt can reenter the phase where it's temperature will once again rise proportional to the amount inputted.
That means that once the temperature of the intermediate storage substance has reached it's melting point, the heat transfer liquid that is to move that heat away to the next point must be capable of doing that job, so that for example, in the case of HTB7, it's temperature does not rise above that which can be inputted from the Turbine exhaust.
HTB3 can receive heat from two different sources, therefore attention should be paid to it's the heat storage capacity compared to that of HTB7.
To define a salt mix:
1. Define the temperatures at which the eutectic mixture should melt.
2. Mix suitable combinations of
NaO2
KNO3
NaNO3
NaOH
in water to meet the requirements.
Evaporate the water.
If necessary consult the supplier.